Towards integration of low carbon energy and biodiversity policies
An assessment of impacts of low carbon energy scenarios on biodiversity in the UK and abroad and an assessment of a framework for determining ILUC impacts based on UK bio-energy demand scenarios
SUPPORTING DOCUMENT – LITERATURE REVIEW OF IMPACTS ON BIODIVERSITY
Defra 29 March 2013
In collaboration with:
Supporting document – Literature review on impacts on biodiversity
Document information
CLIENT Defra
REPORT TITLE Supporting document – Literature review of impacts on biodiversity
PROJECT NAME Towards integration of low carbon energy and biodiversity policies PROJECT CODE WC1012
PROJECT TEAM BIO Intelligence Service, IEEP, CEH
PROJECT OFFICER Mr. Andy Williams, Defra Mrs. Helen Pontier, Defra
DATE 29 March 2013
AUTHORS Mr. Shailendra Mudgal, Bio Intelligence Service Ms. Sandra Berman, Bio Intelligence Service Dr. Adrian Tan, Bio Intelligence Service Ms. Sarah Lockwood, Bio Intelligence Service Dr. Anne Turbé, Bio Intelligence Service Dr. Graham Tucker, IEEP Mr. Andrew J. Mac Conville, IEEP Ms. Bettina Kretschmer, IEEP Dr. David Howard, CEH
KEY CONTACTS Sébastien Soleille [email protected] Or Constance Von Briskorn [email protected]
DISCLAIMER The project team does not accept any liability for any direct or indirect damage resulting from the use of this report or its content. This report contains the results of research by the authors and is not to be perceived as the opinion of Defra.
Photo credit: cover @ Per Ola Wiberg ©BIO Intelligence Service 2013
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Annex A
Table of Contents
1.1 Nuclear 10 1.1.1 Overview of the technology 10 1.1.2 Use in the UK 11 1.1.3 UK biodiversity impacts and their mitigation 13 1.1.4 International biodiversity impacts and their mitigation 20 1.1.5 Conclusions 20 1.2 Coal 23 1.2.1 Overview of the technology 23 1.2.2 UK biodiversity impacts from coal mining and their mitigation 24 1.2.3 UK biodiversity impacts from coal combustion and their mitigation 27 1.2.4 International biodiversity impacts and their mitigation 30 1.2.5 Conclusions 30 1.3 Oil and gas 33 1.3.1 Overview of the technology 33 1.3.2 UK biodiversity impacts and their mitigation 33 1.3.3 International biodiversity impacts and their mitigation 40 1.3.4 Conclusions 41 1.4 Carbon capture and storage (CCS) 43 1.4.1 Overview of the technology 43 1.4.2 Use in the UK 47 1.4.3 UK biodiversity impacts and their mitigation 50 1.4.4 International biodiversity impacts and their mitigation 56 1.4.5 Conclusions 56 1.5 Hydroelectric power 57 1.5.1 Overview of the technology 57 1.5.2 Use in the UK 58 1.5.3 UK biodiversity impacts and their mitigation 59 1.5.4 International biodiversity impacts and their mitigation 63 1.5.5 Conclusions 63 1.6 Onshore wind 66 1.6.1 Overview of the technology 66 1.6.2 Use in the UK 67 1.6.3 UK biodiversity impacts and their mitigation 68
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Supporting document – Literature review on impacts on biodiversity
1.6.4 International biodiversity impacts and their mitigation 72 1.6.5 Conclusions 72 1.7 Offshore wind 73 1.7.1 Overview of the technology 73 1.7.2 Use in the UK 75 1.7.3 UK environmental impacts 76 1.7.4 International environmental impacts 81 1.7.5 Conclusions 81 1.8 Microgeneration of electricity 83 1.8.1 Overview of the technology 83 1.8.2 Use in the UK 87 1.8.3 UK biodiversity impacts and their mitigation 87 1.8.4 International biodiversity impacts and their mitigation 89 1.8.5 Conclusions 89 1.9 Crop-derived biofuels 90 1.9.1 Overview of the technology 90 1.9.2 Use in the UK 91 1.9.3 UK biodiversity impacts and their mitigation 93 1.9.4 International biodiversity impacts and their mitigation 97 1.9.5 Conclusions 100 1.10 Biomass from dedicated energy crops and primary wood production 103 1.10.1 Overview of the technology 103 1.10.2 Use in the UK 104 1.10.3 UK biodiversity impacts and their mitigation 105 1.10.4 International biodiversity impacts and their mitigation 108 1.10.5 Conclusions 111 1.11 Biomass from agricultural and forestry residues 115 1.11.1 Overview of the technology 115 1.11.2 Use in the UK 116 1.11.3 UK biodiversity impacts and their mitigation 116 1.11.4 International biodiversity impacts and their mitigation 118 1.11.5 Conclusions 119 1.12 Biomass from genuinely residual wastes 120 1.12.1 Overview of the technology 120 1.12.2 Use in the UK 121 1.12.3 UK biodiversity impacts and their mitigation 123
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1.12.4 International biodiversity impacts and their mitigation 124 1.12.5 Conclusions 125 1.13 Geothermal electricity 126 1.13.1 Overview of the technology 126 1.13.2 Use in the UK 127 1.13.3 UK biodiversity impacts and their mitigation 127 1.13.4 International biodiversity impacts and their mitigation 129 1.13.5 Conclusions 129 1.14 Tidal stream 131 1.14.1 Overview of the technology 131 1.14.2 Use in the UK 131 1.14.3 UK Environmental Impacts 133 1.14.4 International environmental impacts 136 1.14.5 Conclusions 137 1.15 Tidal range 138 1.15.1 Overview of the technology 138 1.15.2 Use in the UK 139 1.15.3 UK environmental impacts 140 1.15.4 International environmental impacts 143 1.15.5 Conclusions 144 1.16 Wave power 146 1.16.1 Overview of the technology 146 1.16.2 Use in the UK 148 1.16.3 UK biodiversity impacts 149 1.16.4 International impacts 151 1.16.5 Conclusions 151 1.17 Future technologies 154 1.17.1 Overview of the technologies 154 1.17.2 Description of the technologies and their impacts/mitigation 154 1.17.3 Conclusions 156 1.18 Energy grid – transmission and storage 157 1.18.1 Overview of the technology 157 1.18.2 Description of the technologies and their impacts/mitigation 157 1.18.3 Conclusions 160
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Supporting document – Literature review on impacts on biodiversity
List of Tables
Table 1: Power reactors operating in the UK 12 Table 2: Nuclear power environmental impacts – by operation 14 Table 3: Summary of potential biodiversity impacts per unit of energy produced from nuclear energy in the UK 22 Table 4: Summary of potential biodiversity impacts per unit of energy produced from the use of coal for UK energy requirements 32 Table 5: Produced water discharges containing oil between 2005 and 2009 36 Table 6: Oil and chemical releases from offshore installations and pipelines in the UK 37 Table 7: Summary of potential biodiversity impacts per unit of energy produced from the use of oil and gas for UK energy requirements 41 Table 8: Summary of potential biodiversity impacts per unit of energy produced from the use of fossil fuels with carbon capture and storage for UK energy requirements 56 Table 9: Total installed capacity and gross electricity generation from hydropower in the UK in 2010 59 Table 10: The number of possible future hydroelectricity sites in England and Wales classified according to their potential fish impacts 62 Table 11: Summary of potential biodiversity impacts per unit of energy produced from the use of hydropower for UK energy requirements 65 Table 12: Summary of potential biodiversity impacts per unit of energy produced from the use of onshore wind for UK energy requirements 72 Table 13: Offshore windfarm projects in the UK (March 2012) 76 Table 14 Summary of potential biodiversity impacts per unit of energy produced from the use of offshore wind for UK energy requirements 82 Table 15: Summary of potential biodiversity impacts per unit of energy produced from microgeneration of energy in the UK 90 Table 16: UK biofuel volumes per feedstock from the UK (DfT 2011) 91 Table 17: UK land areas used for agriculture and crops for biofuels 92 Table 18: UK biofuel volumes per feedstock imported 93 Table 19: Summary of potential biodiversity impacts per unit of energy produced from the use of crop-derived biofuels for UK energy requirements 101 Table 20: Summary of potential biodiversity impacts per unit of energy produced from the use of dedicated energy crops for UK energy requirements 112
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Table 21: Summary of potential biodiversity impacts per unit of energy produced from the use of biomass from agricultural and forestry residues for UK energy requirements 119 Table 22: Summary of potential biodiversity impacts per unit of energy produced from the use of genuinely residual wastes for UK energy requirements 125 Table 23: Summary of potential biodiversity impacts per unit of energy produced from the use of geothermal power for UK energy requirements 130 Table 24: Summary of potential biodiversity impacts per unit of energy produced from tidal stream energy production in the UK 137 Table 25: Summary of potential biodiversity impacts per unit of energy produced from the use of tidal range energy in the UK 144 Table 26: Summary of potential biodiversity impacts per unit of energy produced from the use of wave power derived energy in the UK 152 Table 27: Summary of potential biodiversity impacts per unit of energy produced from energy transmission and storage in the UK 160
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Supporting document – Literature review on impacts on biodiversity
List of Figures
Figure 1: Power generation in a nuclear plant 10 Figure 2: Power generation in a coal-fired power station 24 Figure 3: Mine fields in the UK 25 Figure 4: Changes in soil pH across England and Wales between 1978 and 2003; (a) Initial soil pH; (b) Annual change 29 Figure 5: Principle of Carbon Capture and Storage 44 Figure 6: Principle of a traditional fossil fuel power plant 45 Figure 7: Principles of post-combustion capture (left) and oxy-firing capture (right) 45
Figure 8: CO2 emission and capture in power plants with and without CCS technology 46 Figure 9: Langeled pipeline running from Nyhamna (Norway) to Easington (UK) 48 Figure 10: Oil and Gas fields in the UK 49 Figure 11: Prospective scenario for a CCS storage network in the Central North Sea 50 Figure 12: Map of the Fossilwise I scenario 54 Figure 13: An offshore windfarm in Lillgrund (Sweden) - Source: ©Ocean Power Magazine 74 Figure 14: Different types of foundations for offshore turbines (from left to right: GBS, monopole, tripod, floating structure) - Source: ©OWE, www.offshorewindenergy.org 74 Figure 15: The Wilney1 offshore substation for the Walney (UK) offshore windfarm. Source: ©Dong Energy 75 Figure 16: Microgeneration by solar PV 84 Figure 17: Microgeneration by wind turbine 85 Figure 18: Microgeneration by hydro 85 Figure 19: Microgeneration by CHP 86 Figure 20: Microgeneration by ground source heat pump 87 Figure 21: Processing steps in ligno-cellulosic ethanol production 103 Figure 22: Principle of geothermal electricity generation 127 Figure 23 - Tidal stream project illustration - ©www.tidalstream.co.uk 131 Figure 24 - Average flow for a Spring/Neap Tide - Source: Atlas of Marine UK Renewable Energy Resources 132 Figure 25: Principle of tidal range harnessing - Source: ©Green Rhino Energy 139 Figure 26: Average Tidal Spring (left) & Neap (right) Range - Source: Atlas of Marine UK Renewable Energy Resources 140
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Figure 27 - Principle of oscillating water column - Source: http://www.energystockblog.com 146 Figure 28 – Two examples of buoyant moored devices: the Duck (©1996 Ramage) and a point absorber (Source: EPRI 2007) 147 Figure 29 - Principle of the edge contour - Source: EPRI 2007 147
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Supporting document – Literature review on impacts on biodiversity
Potential impacts on biodiversity of selected energy technologies
1.1 Nuclear
1.1.1 Overview of the technology
Nuclear power stations use a mature and globally deployed technology that generates electricity from nuclear fuel, currently through the process of nuclear fission whereby heat released from the splitting of atoms is captured. A fission chain reaction is controlled in a thermal nuclear reactor: the fission process takes place in the reactor core which is contained within a pressure vessel and a biological shield: this containment is designed to protect the core from inside intrusion and to prevent radiation leaks from the core in case of any malfunction inside. Inside the core, fuel rods of fissile material
(usually pellets of uranium oxide UO2 with a melting point at 2800°C) are arranged into fuel assemblies, while a moderator, typically made of graphite or water, slows down the neutrons so that they cause more fission and provoke a chain reaction. Control rods, made of material that absorbs neutrons (e.g. cadmium, hafnium or boron) are placed inside the core. They can be inserted or withdrawn from the core to start the reaction, to control its rate or to halt it. Coolant, such as water or gas, passes through the reactor and moves the heat generated to a boiler. From this point forward, the production of electricity at the nuclear power station is similar to any other power station: heat is used to make steam, which is used to drive turbines that produce electricity (Figure 1). Figure 1: Power generation in a nuclear plant
Source: www.world-nuclear.org
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Most nuclear power stations use enriched uranium as fuel, including advanced gas-cooled reactors (AGRs) or pressurised water reactors (PWRs). Uranium must be converted into uranium hexafluoride , and then enriched to increase the proportion of the Uranium 235 (from 0.7% to 3.5- 5.0%). The enriched fuel is then converted into either AGR or PWR ceramic fuel pellets, which are then packed into stainless steel tubes for AGRs to form fuel pins, or zirconium alloy tubes for PWRs to form fuel rods. The pins and rods are then assembled into a fuel element. This process does not apply to the UK’s two remaining Magnox stations, as they use un-enriched uranium. Nuclear plants in operation do not emit greenhouse gases, but their desirability has been debated due to the hazardous nature of their fuel, along with concerns regarding weapons proliferation from nuclear power (the fuel-grade and reactor-grade of plutonium can be used to make nuclear weapons), the status of plants as potential terrorist targets, and the issue of the long-term management of radioactive waste. The high grade waste remains radioactive for thousands of years, and disposal in an unsafe site may lead to radioactive contamination of the environment. Safety concerns have been revived after a powerful earthquake and tsunami destroyed the cooling systems at the Fukushima nuclear plant (Japan) in March 2011. This resulted in radioactivity leaks potentially harming local populations and contaminating local agriculture and soil, fisheries and water. Studies are under way to analyse contamination effects. Nuclear plants require large amounts of water (more than 3,000 L/MWh1) for the condenser cooling water and are therefore situated close to large water masses (lakes, sea). Water is used to cool and condense the steam driving the turbine, and is not driven through the reactor core. The body of water is usually pumped from the environment, used in the cooling tower to absorb the heat from the steam, and ejected at a slightly warmer temperature than its original temperature (usually a few tenths of degrees Celsius).
1.1.2 Use in the UK
The UK has 17 reactors on nine sites, which accounted for 16.4% of electricity produced in the UK in 2010 and represent 11 GW of generating capacity. Nuclear energy does not emit greenhouse gas from fuel burning, but is associated with emissions related to plant construction and decommissioning, and fuel mining, enrichment and reprocessing. It is estimated that in the UK,
nuclear power has a CO2 intensity of about 22 g/kWh (to be compared with 891 g/kWh for coal and 356 g/kWh for natural gas)2.
1 World Nuclear Association, http://www.world-nuclear.org/info/cooling_power_plants_inf121.html 2 World Nuclear Association, http://www.world-nuclear.org/education/comparativeco2.html
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Supporting document – Literature review on impacts on biodiversity
Table 1: Power reactors operating in the UK
Plant Type Present capacity First Expected (MWe net) power shutdown
Wylfa 1&2 Magnox 2x490 1971 Sep 2014
Dungeness B 1&2 AGR 2 x 545 1983 & 2018 1985
Hartlepool 1&2 AGR 2 x 595 1983 & 2019 1984
Heysham I-1 & I-2 AGR 2 x 580 1983 & 2019 1984
Heysham II-1 & II- AGR 2 x 615 1988 2023 2
Hinkley Point B AGR 2 x 610, operating 1976 2016 1&2 at 70% (430 MWe)
Hunterston B 1&2 AGR 2 x 610, operating 1976 & 2016 at 70% (420 MWe) 1977
Torness 1&2 AGR 2 x 625 1988 & 2023 1989
Sizewell B PWR 1188 1995 2035
Total: 17 units 10,962 MWe Source: DECC, 2011; www.world-nuclear.org The UK has a large potential for deployment in theory, and eight sites are currently approved3, that can provide over 16 GW. This decision was not an issue in the UK, where the technology is better accepted than in most of the world: opinion polls even suggesting that support for nuclear power has increased after the Fukushima disaster4. However, further deployment may be limited by the availability of suitable sites for nuclear plants. Another issue is fuel dependency: the UK currently has enough uranium and plutonium stockpiles to fuel three 1 GW reactors for 60 years5. Given the combined powers of the existing reactors, that stockpile corresponds to less than 17 years before more uranium will be required, which will lead to international impacts.
3 Huhne, 2010, ‘Energy Policy Statement’, http://www.decc.gov.uk/en/content/cms/news/en_statement/en_statement.aspx 4 BBC World Service 2011, ‘UK nuclear support rises after Fukushima’, 9 Sept 2011 http://www.bbc.co.uk/news/science- environment-14847875 5 Nuclear Decommissioning Authority, 2007, ‘Uranium and Plutonium: Macro-Economic Study’ http://www.nda.gov.uk/documents/upload/Uranium-and-Plutonium-Macro-Economic-Study-June-2007.pdf
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1.1.3 UK biodiversity impacts and their mitigation
Potential general environmental impacts Nuclear power is a source of electricity that does not rely on fossil fuel and hence does not produce greenhouse gas emissions. However, there are significant environmental impacts arising from this technology, which include long-term waste disposal and the handling and disposal of toxic chemical wastes associated with the nuclear fuel cycle. These are outlined below, largely based on a review by Tucker et al. (2008) unless otherwise indicated. Unlike mining (considered below in the section on international impacts), fuel processing activities (which include enrichment, fabrication, and conversion) are undertaken in the UK and have a much lower land-take, most of which can also be reclaimed. During enrichment, it is estimated that 1% of the site is committed to the storage of waste, and 10% for roads and the plant itself. Cooling towers must also be built if enrichment is performed using gaseous diffusion. The Capenhurst enrichment facility in the UK occupies a 40 ha site (0.4 km2). Both fabrication and conversion facilities in the UK are located at Springfields, Lancashire, comprising 63 ha of land. The land area required by nuclear power plants is comparable to that for coal- and gas-fired stations and around the same as that required by onshore wind power. It is estimated that the total land-take for a 1,000 MW nuclear power plant is between 20 and 80 ha. The land footprint of past and present nuclear sites is estimated to be around 1,000 ha. Present sites are estimated to have land footprint of around 300 ha. The land footprint of decommissioned nuclear sites (since 1989) is around 700 ha (including Oldbury, which was shut down in 2012). Based on the UK Government’s planning documents for new nuclear sites, the new (3 GW) sites will have a land footprint of around 160 ha.. Most plants are surrounded by an exclusion zone of anything between 100 and 500 ha, depending on land prices, land availability and reactor size. The land within the exclusion zone may include site infrastructure or agricultural land, but can also be beneficial to some species, because it may provide secure undisturbed habitats. Due to their requirements for large volumes of cooling water, nuclear plants are in coastal locations, and for safety reasons in areas of low population density. Nuclear land requirements will normally be the highest during the construction phase of a plant, in common with any large-scale electricity generating technology. Impacts will also generally be highest during the construction phase as most disturbance sources and pollution from dust etc., will fall to low levels after construction. The main operational environmental impacts of nuclear power generation probably arise from the use and discharge of cooling water. The water is usually pumped from the sea, used in the cooling tower to absorb the heat from the steam, and ejected at a slightly warmer temperature than its original temperature (usually a few tenths of degrees Celsius). The enormous quantities of water needed for cooling can lead to impingement (trapping) of local fish populations resulting in massive kills6.
6 Pace University, Environmental Costs of Electricity, p287
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Supporting document – Literature review on impacts on biodiversity
Other environmental concerns relate to the many radioactive waste streams created in various parts of the nuclear fuel cycle. What deservedly receives the most attention is the high level waste containing the fission products and/or transuranic (TRU) elements created during energy generation. The spent fuel from nuclear reactors contains radioactive material that presents environmental risks that persist for tens of thousands of years. At present no country has yet successfully implemented a system for disposing of this waste. In most countries, the preferred technological approach is to dispose of the waste in repositories constructed in rock formations hundreds of metres below the earth’s surface. Although several experimental and pilot facilities have been built, there are no operating high-level waste repositories, and all countries have encountered difficulties with their programmes. The issue of waste, both legacy waste from decommissioned reactors and that which would be produced with replacement or new build is therefore a significant general environmental problem and a public concern, although biodiversity impacts are likely to be negligible. Table 2: Nuclear power environmental impacts – by operation
Operation Potential environmental impact
Mining (Uranium) Land take (not extensive in the UK), main uranium producers worldwide are Canada, Australia and Kazakhstan Toxic and radioactive leakage
Milling (separation) Radioactive wastes Air pollution Water pollution Solid waste
Enrichment Minor release of radioactive material
Conversion Land take (permanent) Thermal discharge Impingement and entrainment of aquatic organisms Release of radionuclides (minor) Accident potential Aesthetics
Reprocessing Radioactive air emissions
Radioactive waste Accident potential (handling, storage) disposal Land take Radioactive leakage
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Operation Potential environmental impact
Accident Radioactive emissions in air, soil and water (long-term) Source: Based on Jain et al. (2002) and further developed Potential impacts on biodiversity The most likely biodiversity impacts arising from nuclear power generation in the UK will be associated with the footprint of the nuclear power stations and associated facilities. Although nuclear facilities cover a relatively large area compared to some other power generation plant, their extent is still relatively low in comparison with the total area of most habitats. Furthermore, the eight new nuclear facilities are planned alongside existing plants7, which may reduce their impacts in some situations. Three sites in Dungeness in Kent and Braystones and Kirksanton in Cumbria were ruled out due to concerns over the impact on wildlife and the Lake District National Park8. Three other potential sites have been identified, but are not recommended for early deployment: Druridge Bay, Owston Ferry, and Kingsnorth9. Druridge Bay is part of the Northumberland Heritage Coast, with coastal areas of ecological importance. Owston Ferry would require use of river water for cooling, which could have significant environmental impacts, as well as being less efficient and susceptible to drought. Nevertheless, impacts may occur if sensitive sites are not avoided. Furthermore, because nuclear power stations are located along the coast, then some coastal Priority Habitats, such as Coastal Floodplain Grazing Marshes, Coastal Vegetated Shingle and Sand Dunes have been, and are likely to be, disproportionately affected, although significant areas of these habitats may be protected. Such habitats are sensitive and therefore, if not destroyed by the footprint of the nuclear plant and associated infrastructure, they may be degraded by vehicle traffic, dust and other pollutants during construction and long-term hydrological changes and maintenance of coastal sea defences. However, after construction some rehabilitation and restoration of habitats may be feasible on parts of the site. For example, Sizewell B caused a direct loss of 42 ha of grassland and scrub, most of which had probably naturally regenerated in the last 40 years. The level of 15 ha of grazing marshes was raised during construction, and restoration has been to pasture and woodland/scrub, but this has a significantly lower ecological diversity than the original coastal grazing marsh habitat. The shingle beach in front of the power station was extensively disturbed during construction. The area has been restored and replanted with plant communities taken from the site prior to construction, propagated and then replanted. The recreated vegetation has
7 The new nuclear power stations will be built near existing sites in Bradwell in Essex, Hartlepool, Heysham in Lancashire, Hinkley Point in Somerset, Oldbury in South Gloucestershire, Sellafield in Cumbria, Sizewell in Suffolk and Wylfa in Anglesey.
8 http://www.telegraph.co.uk/earth/energy/8070810/Eight-new-nuclear-power-stations-despite-safety-and-clean-up- concerns.html
9 http://webarchive.nationalarchives.gov.uk/20110302182042/data.energynpsconsultation.decc.gov.uk/documents/atki ns.pdf
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Supporting document – Literature review on impacts on biodiversity
mostly established successfully and has the potential to develop into a vegetated shingle community (AEA 2008a). Overall, the 623 ha site resulted in a 45% increase in heathland and fen, a 30% decrease in coastal habitats including dune, grassland and vegetated shingle, a 15% loss in grazing marsh, and 90% loss of scrub with 20% gain in woodland. Although the biodiversity impacts of nuclear plant can be significant, it should be pointed out that the normal provision of extensive exclusion zones around nuclear facilities may provide benefits for some habitats and species, e.g. as a result of the low levels of disturbance and trampling. Wylfa, Dungeness, Chapelcross, Sizewell, and Hinkley Point sites all contain or border habitats of environmental importance including Natura 2000 sites and SSSIs. For example, at Sizewell British Energy is restoring 91 ha of heath/acid grassland and managing 104 ha of SSSI (AEA 2008a). The Dungeness site covers 91 ha of shingle. There are currently eight closed nuclear plant sites that are being decommissioned or are awaiting decommissioning, and some of the sites protect valuable wildlife habitats: Oldbury power station has silt lagoons that are used as a high tide roosting site by water birds (Middleton et al 2007); nearly two thirds of the Winfrith site are within a lowland heath SSSI10; the area around the Berkeley site is a designated Natura 2000 and SSSI site11; Dounreay includes maritime grassland, cliffs, maritime heath, the beach, the Mill Lade and grassland which are of nature conservation importance. The main operational impacts of nuclear power stations relate largely to the very large quantities of water required for cooling. Very small fish life stages such as eggs and larvae may pass through filter screens and through the entire cooling system (so-called entrainment); while larger fish are generally impinged on intake screens, depending on the size of the fish and of the mesh fitted (Greenwood, 2008). The entrainment losses are considered to have a higher potential impact than impingement. The extent of annual impingement seems to be directly proportional to the amount of water withdrawn for cooling-water (Greenwood, 2008). Such problems are likely to be particularly significant if they affect small lakes or estuaries, and in coastal regions where direct-cooled power plants are concentrated. Indeed, power stations are often sited in estuarine nursery areas or on migratory routes (e.g. for sprat). According to Hossell et al (2006, citing Pisces Conservation Ltd, 2012), 17 power stations in the southern North Sea are estimated to kill sole and herring equivalent to about half of the British commercial landings for the region. It is estimated that over 100 different species of fish are killed (either in the egg, larval or adult stages) during cooling water extraction. The commonest species caught are Sprat (Sprattus sprattus), Whiting (Merlangius merlangus), Flounder (Platichthys flesus) and Sand Goby (Pomatoschistus minutus). Smaller organisms enter involuntarily, entrained by currents, while larger vertebrate animals enter because they are already sick or moribund, or have become disorientated (in dark or turbid waters); larger predators such as Bass (Dicentrarchus labrax) can also opportunistically enter to feed on smaller organisms (Turnpenny et al. 2010). Another study by Greenwood (2008) at the Longannet Power Station, which has very similar water cooling processes as those used for nuclear power, found that it is the largest single source of fish
10 http://www.research- sites.com/UserFiles/File/Archive/Safety,%20Health%20and%20Environment/RSRL%20Winfrith%20Strategic%20Envi ronmental%20Assessment%20June%202011.pdf
11 http://www.nda.gov.uk/sites/berkeley/
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mortality among British coastal power stations, due to its large use of water and location in an important nursery and overwintering area. The study shows that fish mortality is quite predictable in terms of annual abundance and species richness given power station pumping capacity and geographic location; that mortality of juveniles leading to future commercial fisheries losses is low compared to the losses attributable to the fisheries themselves and occurs in a relatively limited geographic area. Turnpenny et al. (2010) conclude similarly. Population- level effects are apparently low based on the study, but cumulative effects of all power stations, including nuclear and fossil fuels power stations that use cooling water may, however, be relatively high. The thermal discharge from nuclear power plants also impact fish and benthic communities. Fish richness and diversity are shown to be decreased because of thermal discharges (Teixeira et al., 2012). Thermally polluted rocks may also lead to reduction in the numbers or presence of sessile invertebrates or microalgae vegetation, with a negative impact on fishes using the habitat. In general, however, the disturbance occurs at the point of discharge, but scientific results show that in certain cases, even though outflow volumes are relatively low (40 and 80 m3/s), effects were observed as far as 500-600 m from the discharge (Teixeira et al., 2009). Thermal pollution also reduces dissolved oxygen levels and increases acidity. This can affect common shrimp and lobster larvae amongst other marine species (Bamber & Seaby, 2004). Alteration of flow regimes and associated physical variables (e.g. sediments) can also result in a shift in species composition. There is, however, recognition that removal of organisms from estuaries and marine waters during cooling-water extraction is a greater potential problem than thermal pollution (Greenwood, 2008), although that may depend on the region, since in hot regions higher temperatures of released water may result in thresholds for species survival being exceeded. Thermal pollution may also become a barrier to migratory fishes, although it does not seem to have impacts if the temperature increase is below 3°C (Turnpenny et al. 2010). Some pollution effects in the discharged waters may also occur, from biocides residues used for anti-fouling. There is the possibility of biodiversity impacts from radiation from effluent, waste and accidents. Radiation is also produced during decommissioning; for example, the Winfrith site is producing around 41 kBq of airbourne alpha radiation, down from around 100 kBq in 2002, and around 10 resp. 30 kBq of alpha emitters into the River Thames and the Lydebank Brook12. Hossell et al. (2006) note that chronic and acute exposure to radiation doses from radioactive waste may result in reproductive damage, behavioural change, larvae/juvenile survival and, in more extreme cases, DNA damage and genetic mutation. However, they do not provide any evidence of such effects having any population level impacts. At the moment there seems to be no indication that current levels of radioactive contamination in the UK are having any measurable impact on habitats or species populations (Tucker et al., 2008). Potentially severe human health and environmental impacts would result from a serious nuclear accident or terrorist attack leading to high levels of radioactive contamination. Scientific research studies of these impacts are scarce, specifically on biodiversity and ecosystem services, and little
12 http://www.research- sites.com/UserFiles/File/Archive/Safety,%20Health%20and%20Environment/RSRL%20Annual%20Environment%20R eport%202011.pdf
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Supporting document – Literature review on impacts on biodiversity
knowledge about long-term impacts is available (Von Wehrden et al., 2012). Most information on such impacts comes from studies carried out in the aftermath of the Chernobyl accident in 1986, which released 80 petabecquerel of radioactive caesium, strontium, plutonium and other radioactive isotopes into the atmosphere, polluting 200,000 km2 of land in Europe. A review by von Wehrden et al. (2012) sums up the findings from various studies on Chernobyl, on biodiversity and ecosystem services. It shows that the environmental consequences of nuclear accidents include fallout of radioactive substances, biological contamination, and even changes in the behaviour, physiology, and morphology of species. Recorded impacts to species include reduced brain size in a range of birds species compared to those outside the core zone of the Chernobyl reactor site, lethal mutations in various plants and animal species, morphological changes in plants, damselflies, dipteral and mice; reduced reproduction rates; and modified genetic structures of fish and frogs. At population levels, studies show that elevated radiation levels negatively impact the abundance of entire species groups such as insects and spiders or small mammals. Even low radiations have an influence, although this is poorly understood, with evidence of mutation rates on Drosophila and weakening of immune and reproductive systems of small mammals. At higher trophic levels, top predators can accumulate radiation as shown in the Tench (Tinca tinca). The accident itself caused widespread death of organisms in the vicinity of the site. In contrast, the accident also caused major land-use change, due to the abandonment of the agricultural and urban areas close to the accident site, which increased some wildlife species abundance. Von Wehrden et al. (2012) also examine the implications for ecosystem services, showing that many provisioning services are negatively affected, with the effects of Caesium contamination still measurable today. Freshwater and associated fish are not consumable, and agricultural land cannot be used within the ~2,700 km2 exclusion zone, but also beyond, where monitoring requirements result in high financial burdens on farmers. Even far away from the accident site, timber in Sweden, fish in Finland, agricultural crops in Scandinavia, wild foods in Poland, game meat in Germany, and berries in Finland may not be consumed or used anymore. The 2011 Fukushima disaster was smaller in its spatial extent, but introduced high radiation leakage into the marine environment, which currently has unclear long-term consequences, but may lead potentially to issues of bioaccumulation in big fishes. Studies on the impacts of the Fukushima accident on bird populations and other species have begun, so scientists may follow from the time of the accident the impacts of nuclear radiations on biodiversity (Braxton Little, 201213). Potential mitigation measures The most important mitigation measure is appropriate siting. If this takes into account the results of thorough Strategic Environmental Assessments (SEA) and project-level Environmental Impact Assessments (EIA), and Appropriate Assessments (as required for Natura 2000 sites under the Habitats Directive), then the most significant impacts on sensitive and important habitats and species can be avoided. This need is especially important for nuclear plants, because of their location in coastal and remote areas, which are often of high biodiversity importance.
13 http://www.janebraxtonlittle.com/wp-content/uploads/2012/03/Fukushimas-Nuclear-Disaster.pdf
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A number of mitigation options are available to reduce impingement and entrainment effects. Fish recovery and return (FRR) systems, for instance, may be installed at new nuclear plants to reduce fish impingement and incorporate modifications that reduce the risk of fish injury. Nonetheless, survival rates of Eels and Lampreys from fish return studies have been low and, given the recent EC Eel Regulation and the status of Lampreys under the Habitat’s Directive, there is an urgent need to investigate and develop suitable design criteria to safely handle these species (Turnpenny et al, 2010). Other measures to reduce impingement and entrainment include (from Greenwood 2008): Fish collection and return systems, which allow the return of fish to water after impingement, but these are difficult to retrofit and species have different survival rates Fish diversion systems, e.g., angled screens with pumped return to the water body, that reduce likelihood of impingement, but these have high costs and may be blocked by debris Physical barriers, e.g., nets, that reduce the likelihood of fish entering the immediate vicinity of the cooling-water intake system, but they depend on location Behavioural barriers, e.g., light or acoustic measures that deter fish from entering the region of cooling-water abstraction, but different species may respond differently (attraction issue); Turnpenny et al. (2010) report reduced losses to impingement from acoustic fish deterrents Closed-cycle cooling (cooling towers) are possibly the most effective means to reduce losses of organisms through impingement and entrainment, but have high costs, increase GHG emissions and have visual impacts (due to the size of structures) Stock enhancement, that augments abundance of stocked species, but this cannot be done for all species, disrupts genetic composition and has high costs Plant outages/flow reductions can be synchronised with times of peak abundance, e.g., of juvenile stages, but this results in lower generation potential and peak abundance depends on species Reduction in intake velocity of cooling-water, to increase likelihood of escape from intake current, but this depends on the species swimming capabilities and has high costs Turnpenny et al. (2010) report that entrainment has been less studied than impingement, but that with current mitigation measures for impingement, it may have larger impacts. Mitigation measures to reduce thermal pollution, radioactive and toxic pollution and accidents include:
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Supporting document – Literature review on impacts on biodiversity
Further reducing the temperature of the water discharged, although there may be technical difficulties in achieving this, Ensuring that liners, roofs and other insulating structures to reduce impacts of possible radioactive leakage are effective, well-designed and properly maintained, but as shown earlier the issue of storing radioactive waste is not expected to be solved in the near future.
1.1.4 International biodiversity impacts and their mitigation
Potential impacts The predominant international environmental impact from nuclear power consumption in the UK is the mining of uranium ore. As there are no uranium reserves in the UK, most is extracted from Australia, Canada and Kazakhstan (SDC, 2006). Although the environmental impacts of a uranium mine are similar to those of other metalliferous mining, the radioactive content of waste materials (e.g. spoils and tailings) requires storage locations impervious to leakage of hazardous/radioactive substances. Potential impacts are specified in the section on international impacts below. Carvalho et al. (2005) show that uranium mining may have toxic and radioactive impacts, due to the chemicals used in the process of extracting uranium and the possible leaking of uranium. While precautions are usually taken that mitigate these risks, such as impervious layers under the storage sites, roofs, etc., accidental breaking of the bottom liner and/or overflows (e.g. in the case of heavy rains) can occur (Carvalho et al., 2005). Milling and mining can poison birds, through ingesting contaminated waters; and abandoned mines can form lakes that are hazardous to wildlife; and birds, in particular, may ingest contaminated water close to mining sites (Sovacool, 2009). Mining occupies approximately 20-50 hectares of land (0.2 - 0.5 km2) depending on the technique, with 1/3 of the occupied land from underground extraction disturbed. Most of the land needed in the milling process is for the creation of a tailings pond (12-30 ha), where the non- uranium radioactive residues are disposed. Potential mitigation measures After decommissioning, most of a mine and milling site is reclaimable. More and more, the extraction of ores, site management, restoration and aftercare are carried out to international environmental standards to bring the land back into productive and amenity use (SDC, 2006).
1.1.5 Conclusions
Summary of known impacts Impacts on biodiversity from nuclear power mainly result from the footprint of the mining, milling and processing activities, as well as power plants and storage facilities, which are often in remote and coastal locations of high biodiversity importance. Other impacts from the operation of the power plants relate to effects on aquatic organisms from the use of cooling water, which
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include thermal pollution, impingement and entrainment that cumulatively may have potential impacts at a population/habitat level. Radioactive and toxic leakages from nuclear plants are expected to have low impacts, unless in the case of major accidents, but scientific knowledge about the long-term effects of low radiation is still scarce. Knowledge gaps and required research Information on the actual biodiversity impacts of uranium mining for UK requirements does not appear to be readily available. The impacts of the use of cooling water for nuclear power generation have been studied, but there is insufficient information available to realistically assess these impacts on aquatic species. Likewise, although there is no evidence of population level impacts from radiation from effluent and waste (e.g. thr0ugh reproductive damage, behavioural change, larvae/juvenile survival and, in more extreme cases, DNA damage and genetic mutation) such effects require further research. Reports of species exposure to extreme radiation are few due to difficulties of practical experimentation with radiation or because such events are rare in the operation of nuclear sites. Some studies have looked at the long-term effects of nuclear testing, but these may not be applicable to nuclear energy production. The Chernobyl and Fukushima nuclear accidents have provided some insight to the short-term and long-term effects of radioactive exposure, but the research on this is still preliminary.
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Supporting document – Literature review on impacts on biodiversity
Table 3: Summary of potential biodiversity impacts per unit of energy produced from nuclear energy in the UK
Selected Nuclear technology
Impacts in UK
Positive impacts Low: Some species (e.g., nesting birds) may benefit from exclusion zones due to the lack of human disturbance within them.
Direct mortality Uncertain: Losses of fish and marine invertebrates occur in cooling water intakes, but population level effects are uncertain.
Direct habitat loss Low: Habitat loss from footprints of power stations, processing facilities and waste storage facilities is relatively low, but some important habitats may be affected as most existing sites are on coastal habitats, as new sites probably will be.
Indirect habitat Low: As other power stations - ecosystem disruption from hydrological degradation changes, pollutants and thermal disruption (from warmed cooling water) can reduce food resources, but impacts are likely to be localised. Impacts from low-level radiation from effluent and waste are uncertain, but unlikely to be significant.
Disturbance Low: Moderate impacts are likely during construction, but operational impacts will be low, especially because many new sites will be alongside existing nuclear plants.
Secondary impacts None likely.
Potential for Moderate: Avoidance of the most important habitats should be possible, and mitigation technical measures can reduce other impacts, but some residual impacts will occur.
OVERALL LOW DETRIMENTAL RESIDUAL IMPACT
Potential for Variable: Depends on habitat and site, but many coastal habitats cannot be ecological easily restored / created. Compensation for fish mortality could be achieved by compensation reducing other sources of mortality, e.g. by fisheries.
Impacts outside the UK
Positive impacts None likely
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Selected Nuclear technology
Direct mortality Variable: Uranium mining impacts will vary according to the locations and habitats impacted and the mining and mitigation methods used. Additional variable impacts from fuel transport and processing may occur.
Direct habitat loss Moderate: Due to footprint of mining, milling and processing activities.
Indirect habitat Moderate: Potential impacts from leakage of radioactive and toxic materials. degradation
Disturbance Moderate: Disturbance likely from mining machinery and operations, etc.
Secondary impacts Uncertain: Roads to mines and infrastructure may lead to secondary developments.
Potential for Uncertain: Avoidance of protected and other sensitive sites may substantially mitigation reduce impacts but uranium mining may be deemed too important for such considerations.
OVERALL MODERATELY DETRIMENTAL RESIDUAL IMPACT
Potential for Variable: May be low if natural habitat impacted, but will depend on habitat ecological and site. compensation
1.2 Coal
1.2.1 Overview of the technology
Coal fired power stations are one of the oldest ways of electricity generation, and are the main source of electricity in many countries. Coal fired power stations are the cheapest, but most polluting way of generating electricity, releasing the highest levels of pollutants into the air of all the technologies reviewed in this report. The process of generating electricity in coal power stations is rather simple. Coal is usually first pulverised and then burnt in a combustion chamber. The heat energy produced from the burning of coal is used to generate steam that is used to rotate one or more steam turbines. The heat energy generated from the combustion of coal is converted to mechanical energy inside the steam turbine. The steam turbines are connected to electrical generators. The spinning of the generator shaft results in the production of electricity.
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Supporting document – Literature review on impacts on biodiversity
Figure 2: Power generation in a coal-fired power station
1.2.2 UK biodiversity impacts from coal mining and their mitigation
Potential general environmental impacts The environmental impacts of energy generated from coal are well known and occur during coal surface or underground mining, processing, transportation and combustion. Each stage of this process has specific effects (Tucker et al., 2008). The main impact from surface mining is the land take, which can be significant, although some post extraction rehabilitation and restoration is often feasible. A surface mine is typically worked for 3-5 years before being restored. Other operational impacts from surface and underground mining include the production of silty run-off and solid waste, and localised dust from coal haul roads, topsoil stockpiles, and coal extraction, particularly in areas of low rainfall and high winds (Farmer, 1993). These will induce direct and indirect impacts on biodiversity (Tucker et al., 2008). Additional environmental impacts of underground mining, with insignificant biodiversity impacts, are land subsidence and the emission of coal mine methane. In 2010 UK coal mining was producing around 7.3 million tonnes from underground mining (mainly from 6 deep mines), and around 10.4 million tonnes from surface mining at 41 sites, 14 in England, 8 in Wales, and 19 in Scotland (BGS 2012). Current surface mines are located mostly in lowland Scotland14, northern and central England15, and South Wales16. There is still over 35 million tonnes of coal left at these sites, and the UK also has 22 million tonnes of permitted reserves of opencast coal at unworked sites17.
14 South Lanarkshire, East Ayrshire, Midlothian, Borders, Fife, West Lothian, North Lanarkshire, Dumfries and Galloway
15 Durham, Northumberland, Shropshire, Leicestershire and Derbyshire
16 East Pit in Amman Valley, Nant Helen, and Selar in the Neath valley (http://www.coal.com/)
17 http://www.bgs.ac.uk/mineralsuk/mines/coal/occ/home.html
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Each surface mine site may cover from 25 to 1,000 ha including the mine and handling areas. The current total area of surface mining in the UK is not easily calculated, but a rough estimate suggests it is about 8,200 ha18, (i.e. 0.033% of the UK terrestrial surface area).
Figure 3: Mine fields in the UK
Potential biodiversity impacts Coal surface mining results in the destruction of the vegetation and soils, leading to the loss of habitats and associated species. The impact of such losses on UK habitats and species depends on the scale and location of mining. Surface mines may be developed in many locations and could potentially affect a wide variety of habitats within the regions identified in Figure 3. However, it is likely that upland areas, forests, wetlands and protected areas will be avoided. Consequently, many new surface mines will be located on farmland19, which will result in relatively minor temporary biodiversity impacts. However, some habitats that are of moderate biodiversity importance but not protected may temporary lost, such as some semi-natural grasslands. As discussed in the next section, some of these habitats may be restorable after mining ceases (which is typically after 3-5 years). However, interim losses may be significant, and long-term hydrological and soil impacts may preclude the restoration of some sensitive habitat types.
18 Average 200 ha mine size x 41 mine sites
19 E.g. the recent approval of a surface mine on 30ha of farmland in Northumberland http://www.dcservices.co.uk/Energy_Minerals/article/1147183/permission-granted-new-surface-coal-mine- northumberland/
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Supporting document – Literature review on impacts on biodiversity
Without restoration, the harsh environmental conditions on mining spoil and coal ash (e.g. high pH, toxic metals and free-drainage) can lead to the creation of some unusual habitats with high ecological value, especially for some rare plants and invertebrates (Bradshaw 1999; Gilbert 1991; Kendle & Forbes 1997; Sukopp & Hejny 1990; all cited in Tucker et al. 2008). A good example of such habitats is the UK BAP priority habitat “Open Mosaic Habitats on Previously Developed Land”. However, only a minority of ex-mining/ post-industrial sites acquire rare habitats and species, and it is equally likely that new mines will utilise remaining areas of industrial land and thus as much of this priority habitat may be destroyed as created. Therefore the overall impacts of new coal mining on this habitat is considered to be neutral (Tucker et al., 2008). Consequently, the creation of large areas of mining spoil and coal ash is not desirable with respect to overall biodiversity objectives. Many watercourses in surface and underground mining sites are affected by acid mine drainage. Once in the watercourse, its biodiversity is affected both by the toxic effects of metal hydroxides and by the smothering effect of their deposition on the river bed. This can result in habitat loss or degradation and impacts on aquatic fauna, depending on the concentration of pollutants and the aquatic habitats affected (Tucker et al., 2008). Mitigation measures The main means of avoiding and reducing mining impacts on biodiversity is through underground mining, although as described above significant impacts can remain, especially if mines and coal processing, storage and transport terminals are located on important habitats. It is therefore important that whatever the means of extraction is, mines and associated infrastructure are located appropriately, taking into account the results of SEAs, EIAs and, if Natura 2000 sites may be impacted, Appropriate Assessments in accordance with the Habitats Directive. In this regard, as a result of the large area that could be potentially affected by coal extraction, SEA would have an important role to play in avoiding impacts by identifying vulnerable and important sites and possible alternative locations.
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The long-term impacts of mining can also be reduced by rehabilitation and restoration. In fact surface coal mining areas must be restored to their original condition according to the Surface Mining Control and Reclamation Act of 1977. This often results in the restoration of grassland or arable habitats of low biodiversity value. However, restoration of the former habitat / land use is not always possible, which can enable the creation of higher value habitats, such as wetlands in opencast sites and depressions created by subsidence (Perrow & Davy 2002; Davies 2006). In some situations, if it is appropriately planned, coordinated on a landscape scale, carefully implemented and managed over the long-term, restoration can secure sites and create some valuable habitats that can help reverse previous losses and fragmentation20. Acid mine discharges can be treated using abiotic or biological filter systems (Johnson & Hallberg 2005). The UK currently has 53 such schemes treating 117 km of water courses21.
1.2.3 UK biodiversity impacts from coal combustion and their mitigation
Potential biodiversity impacts In the past the burning of coal was a major contributor to air pollution through acid emission and deposition in the UK and continental Europe. These pollutants are notably particulates, sulphur dioxides, nitrogen oxides and ozone, a secondary pollutant formed from oxides of nitrogen and volatile organic compounds (Tucker et al., 2008). These pollutants are directly toxic to plants but have greater indirect effects through acidification and eutrophication. Eutrophication consists of an increase in fertility due to nutrient enrichment, notably in nitrogen. Acid deposition can also result in acidification of soils and freshwater ecosystems and impacts on vegetation through direct toxicity, changes in nutrient availability and other chemical processes (RoTAP 2012). These indirect impacts of acid deposition primarily affect natural and semi-natural ecosystems and in turn impact on related ecosystem services (Payne, 2012). For example, the deposition of nitrogen oxides is known to be indirectly negatively correlated with plant species richness (number and traits) in heathlands and acid, calcareous and mesotrophic grassland habitats in the UK. Depending on the habitat types, this loss can result from acidification or eutrophication. There is a very significant reduction in species richness with nitrogen deposition in acid grassland and heathland mainly due to acidification (Maskell, 2010). For example, at a nitrogen deposition rate of 17 kg Nha-1 year-1, which is possible in the UK, there is a 23% species reduction compared to grasslands receiving the lowest levels of nitrogen deposition (Stevens et al, 2004). There is also a significant reduction in species richness in calcareous grassland but due to eutrophication. Eventually, loss of species richness from N deposition occurs in infertile mesotrophic grasslands and heathland (Maskell, 2010). However, knowledge of the impacts of nitrogen deposition on individual species is restricted to a very limited range of species. For example, it has been demonstrated that in heathland habitats
20 http://www.ukcoal.com/businesses/surface-mining/overview-sm
21 http://coal.decc.gov.uk/en/coal/cms/environment/schemes/schemes.aspx
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Supporting document – Literature review on impacts on biodiversity
in the UK, nitrogen induced a significant loss of bryophytes (ie mosses, hornworts, and liverworts), which did not induce a significant increase in abundance of mesofauna and microfauna, but did cause significant changes in microfauna community structure (Payne, 2012). A study considered the effects of multiple pollutants (ozone and nitrogen) on species composition, ecological groupings and indicator species in UK acid grasslands. It demonstrated that ozone is a key agent in species compositional change but is not associated with a reduction in species richness or diversity indices. But it demonstrated the effects of multiple interacting pollutants, which may collectively have a greater impact than any individual agent (Payne, 2011). Critical loads (ie thresholds below which, according to current knowledge, there will be no damage on an ecosystem) have been identified for pollutants and pollutant deposition levels mapped in relation to these. However, a study demonstrated that many individual vascular plant species of acid grasslands, calcareous grasslands and heathlands in the UK start to decline at low nitrogen levels, far below claimed current critical load levels (Henry, 2011). The substantial switch from coal to gas in the UK and other technological developments have greatly contributed to reduced air pollution over recent decades (RoTAP 2012). Concentrations of sulphur dioxide in UK surface air have declined to values that are thought to no longer pose a direct threat to sensitive plant species. Deposited sulphur has also decreased in the UK, by 80% between 1986 and 2006, allowing partial recovery of sensitive ecosystems from the effects of acidification (RoTAP 2012). Between 1978 and 2003, there have been widespread decreases in soil acidity in England and Wales and at least part of this decrease and its regional variation are explained by decreased sulphur deposition from the atmosphere (Kirk, 2010). There has been a reduction in the area of Broad Habitats exceeding critical loads for acidity from 71% in 1996-98 to 54% in 2006-08. Exceedance is projected to decline to 40% by 2020. However, detailed monitoring, research and modelling indicates that air pollution from nitrogen oxides and ozone remains a widespread problem over much of the UK. Large areas of the UK currently have nitrogen deposition at rates that exceed the critical loads and are predicted to continue to do so (Payne, 2011). RoTAP reports that the critical level of 1 μg m-3 nitrogen deposition is exceeded over 69% of 1-km squares in the UK, implying that adverse effects on the cover of sensitive bryophyte and lichen species may be expected over most of the country. The critical level of 3 μg m-3 for higher plants is exceeded over 19% of the UK; however this is mainly in areas of high NH3 emissions (i.e. primarily due to the influence of fertiliser and livestock rather than energy production).Virtually all woodlands will be subject to pollution above critical loads as woodland is an efficient interceptor of airborne pollutants. The likely impacts are particularly great on sensitive low nutrient habitats of high conservation importance, including many SSSIs. A substantial percentage (58%) of the total area of sensitive UK habitats is above the relevant critical load based on deposition data for 2006-08 (RoTAP 2012). The UK analysed critical loads on Habitats Directive Annex I habitats as part of its Article 17 Conservation status report (JNCC, 2007). This revealed that 33 out of 51 assessed Annex I habitats are probably threatened by acid deposition and nitrogen deposition.
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Figure 4: Changes in soil pH across England and Wales between 1978 and 2003; (a) Initial soil pH; (b) Annual change
Source: Kirk, 2010 However, careful interpretation of critical load predictions is required. Exceedance of critical loads only indicates that there is a risk to the ecosystem, it does not indicate that impacts have occurred or will occur. Nevertheless, evidence from national vegetation and plant species mapping indicates that there has been a widespread detectable shift in vegetation types towards those of nutrient enriched conditions (Preston et al. 2002). The other main impacts of coal combustion are land use, the production of greenhouse gases
(e.g. CO2), thermal waste and thermal discharge (see environmental impacts of nuclear), with their associated direct and indirect impacts on biodiversity (Tucker et al., 2008). Although it is well documented that the effects of climate change resulting from increases in greenhouse gases in the atmosphere are having increasing impacts on biodiversity in the UK, and globally, the review of these impacts is outside the scope of this study. Potential mitigation measures
The principal means of mitigating SO2 and NOx impacts is through the reduction of emissions, as little can be done to reduce impacts after deposition has occurred. Measures to reduce emissions include regulatory and other policy measures to reduce overall energy demand, energy production from coal and to increase use of clean-coal technology. Management measures, such as increased grazing, cutting and burning, may be used to reduce nutrient levels and vegetation in some habitats that are affected by eutrophication (such as heathlands and some grasslands). But requirements are not well understood and such measures are not always practical, may be damaging in themselves and can be expensive, especially given the area impacted. Hence the need to reduce emissions first and foremost.
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Supporting document – Literature review on impacts on biodiversity
1.2.4 International biodiversity impacts and their mitigation
Potential impacts In 2010, 59% of the coal used in the UK was imported, mainly from Russia (37%), Colombia (24%), USA (17%) and Australia (12%). The environmental impacts of coal mining, processing and transportation will thus occur both in the UK and abroad. The level of environmental impact will depend on the environmental regulations for coal in these countries, which may be less strict than in the UK. For example, in Colombia the Mining Code establishes areas protected from exploration and mining operations, such as national and regional Natural Parks. But these safeguards are not respected. According to public statements by Carlos Rodado, ex Minister of Mining and Energy, since the Mining Code was approved in 2001, “mining concessions have been granted in areas like national parks and moorlands". In 2010, the Government approved Law 1382 that reformed the Mining Code. It increased the amount of areas protected from mine concessions, including Ramsar moorland and wetland ecosystems. Between the approval and ratification of the Law, the area licensed for mining increased by approximately 80%. Ultimately, the Constitutional Court abolished the reform because no prior consultation was done. It can be suspected that environmental impacts due to coal mining are of great importance (PBI Colombia, 2011). The mean residence time of nitrogen oxides in the atmosphere is approximately 30 hours and mean travel distances are 1,000 km before they are deposited. Travel distances are also likely to be much greater for emissions from tall power station chimneys than from vehicles. Therefore,
NOx deposition does not occur only in areas with high emissions, such as power plants. Moreover, 85% of nitrogen oxides emitted by the combustion of coal in the UK is transported elsewhere, so that their environmental impacts also occur outside the UK (RoTAP, 2012).
1.2.5 Conclusions
Summary of known impacts The main UK biodiversity impacts of energy generated from coal will be the result of habitat loss due to coal mining (especially open cast or surface) and acid mine drainage impacts on aquatic systems. Most of the current impacts of coal are likely to be low with respect to UK BAP Priority Habitats and Priority Species. This is primarily because the main impacts of energy production from coal result from habitat loss from open cast mining. Presently, such mines cover a very small proportion of all Priority Habitats and the habitats of most Priority bird species, so that their exposure is very low. Furthermore, some bird habitats can be at least partly restored or compensated for, and therefore the adaptive capacity of some species may reduce the immediate impacts of habitat loss (Tucker et al., 2008). Some habitats and species may be subject to wider indirect impacts, e.g. as a result of pollution
from acid mine drainage, siltation, SO2 and NOx emissions. However, although such impacts will go beyond the mine footprints, exposure rates from water pollution are likely to be very low. Similarly, sensitivity and exposure levels to significant acidification and nitrogen deposition
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impacts are likely to be low now as a result of cleaner coal combustion technologies (and EU emissions regulations), the recent decline in coal use and the tendency for most NOx deposition to occur outside the UK. Nevertheless, it is anticipated that some habitats, including some Priority Habitats will be subject to moderate impacts from nitrogen deposition. Knowledge gaps and required research The environmental impacts of coal mining and power generation are well understood. Similarly, there is good evidence of the direct impacts from habitat loss due to mining activities, but also extensive experience with the positive impacts of habitat restoration of closed mines. While the indirect impacts of coal mining and power generation such as acidification and nitrogen deposition is known to have negative impacts on heathlands and grasslands and plant species richness (number and traits), the impacts of nitrogen deposition on individual species are less certain. Further, although not fully understood, there is evidence that the effects of multiple interacting pollutants may collectively have a greater impact on biodiversity than any individual agent. Finally, the production of energy from coal results in the highest emissions of greenhouse gases of all the technologies reviewed in this report, and thus contributes greatly to climate change which is having documented impacts on biodiversity in the UK, and globally. But the estimation of such climate change impacts is beyond the scope of this study.
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Supporting document – Literature review on impacts on biodiversity
Table 4: Summary of potential biodiversity impacts per unit of energy produced from the use of coal for UK energy requirements
Selected technology Coal
Impacts in UK
Positive impacts Low: Post-extraction restoration can in some cases provide habitats of higher biodiversity value than present at the start of the mining.
Direct mortality Low: Some losses from machinery, e.g. of ground-nesting birds in open cast mines and spoil areas.
Low: SO2 from combustion is toxic to sensitive plant species such as lichens, but emission levels no longer pose a direct threat to them.
Direct habitat loss Moderate: Extensive habitat areas can be lost for open-cast coal extraction and spoil heaps. Direct footprint of power stations are relatively small and are not located on important habitats.
Indirect habitat Moderate: Acid mine drainage and silt impacts on aquatic habitats. Hydrological degradation disruption of surrounding habitats from drainage operations and possible
subsidence. Combustion contributes to acidification from SO2 emissions and
deposition, and deposition and eutrophication from NOx.
Disturbance Moderate: Substantial disturbance from operational mines. Low: disturbance from operating power stations.
Secondary impacts Low: Contributor to the requirement for port developments.
Potential for mitigation Moderate: Avoidance of the most important habitats should be possible, and technical measures can reduce other impacts, but residual impacts will occur.
Future SO2 and NOx emissions from combustion assumed to be low due to new regulations and increasing use of clean-coal technology.
OVERALL RESIDUAL MODERATE IMPACTS
Potential for ecological Variable: depending on habitat type involved, but most that are likely to be compensation impacted can be restored or enhanced. Some post-mining habitats are of high ecological value.
Impacts from mining outside the UK
Generally the same as the impacts in the UK.
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1.3 Oil and gas
1.3.1 Overview of the technology
The basic principle of electricity generation from oil and gas fired power stations is similar to that of coal fired power stations, i.e. to convert heat energy produced by the combustion of fuel into mechanical energy inside the turbine which is used by the electrical generator to produce electricity. Oil and gas fired power stations are however different from coal fired power stations as the conversion of heat energy to mechanical energy in the former case happens in a gas turbine whereas in case of later it take place in a steam turbine. Oil and gas fired power stations have become very popular since the 1990’s due to the relatively clean burning characteristics of these fuels.
1.3.2 UK biodiversity impacts and their mitigation
The environmental impacts of energy generated from oil and gas are well known and occur during exploration, extraction, transportation, refining, combustion and decommissioning. Each stage of this process has specific effects, and those that may have significant biodiversity impacts are described below. In 2009, indigenous production of oil and gas met around 80% of the UK primary demand in oil and gas (DECC, undated). For example, in 2010, 38% of the natural gas used in the UK was imported. However, UK production of oil and gas is now in decline. Indeed, the latest projections show that the production of crude oil, natural gas liquid (NGL) and gas will decrease until 2030 in the UK Continental Shelf (UKCS). On the other hand, the UK primary energy demand will slightly increase for oil and decrease for gas (DECC, undated). Therefore, the import proportion may increase for oil and remain stable for gas. The environmental impacts of oil and gas exploration, extraction and transportation will occur both in the UK and abroad. The UK may contain thousands of cubic kilometres of shale gas reserves, including 5,700 km3 of proven reserves in the Lancashire area22. At the timing of compiling this review, the potential large-scale extraction of shale gas through fracking (ie hydraulic fracturing of rock) was not foreseen and no studies of its potential biodiversity impacts have been carried out. Therefore, the impacts of shale gas extraction are not covered in this review, as they require a more dedicated detailed study.
1.3.2.1 Oil and gas exploration, extraction and decommissioning Potential impacts
22 http://www.utilityweek.co.uk/news/news_story.asp?id=198157&title=UK+shale+gas+reserves+could+be+300+times+e arlier+estimates
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Supporting document – Literature review on impacts on biodiversity
Virtually all oil and gas exploration and extraction occurs offshore, and this together with decommissioning leads to noise that may have significant and widespread impacts on marine species (Tucker et al., 2008). In particular, noise from gas and oil exploration, drilling and production rigs is likely to cause significant disturbance to marine mammals (Boesch, Rabalais, 1987), especially because the ability to perceive biologically important sounds is critical to marine mammals (Gedamke et al., 2011). A number of studies have shown that cetaceans may avoid or leave an area because of noise (Richardson, Wursing, 1995; Simmonds et al., 2003). Stress in marine mammals due to noise may also cause the disruption of normal activities, such as resting, feeding and social interactions (Fair and Becker, 2000). Underwater noise from air guns used in seismic surveys for oil and gas are of particular concern because they create intense sounds that have peak frequency bands overlapping those used by baleen whales. These sounds may cause disturbance and possible injury or death of marine mammals (McCauley et al., 2000). Acoustic disturbance can interfere with their natural functions and it is known that noise can cause temporary or permanent reduction of the auditory senses (Fair and Becker, 2000). The potential for airgun “shots” to cause acoustic trauma in marine mammals is poorly understood, although a study that examined these impacts on baleen whale showed that whales at 1 km or more from seismic surveys were likely to be susceptible to temporary threshold shift (TTS) onset levels, i.e. a temporary loss of hearing (Gedamke et al., 2011). Some studies also suggest that anthropogenic noise may increase the bycatch of cetaceans, collision with vessels and mass strandings, probably as a result of auditory damage or disruption of important acoustic signals (Perry, 1999). Evidence of interference with baleen whale acoustic communication is weak. A study investigated whether Blue Whales (Balaenoptera musculus) changed their vocal behaviour during a seismic survey with a low-medium power technology (sparker). It demonstrated that Blue Whales called consistently more on seismic exploration days than on non-exploration days as well as during periods within a seismic survey day when the sparker was operating. This increase was observed for the discrete, audible calls that are emitted during social encounters and feeding. This behaviour presumably represents a compensatory behaviour to the elevated ambient noise (Lorio et al., 2010). In response to these concerns, the following measures have been taken to minimise the potential impacts of seismic surveys on marine mammals. The Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001 implements the EU Habitats Directive for all oil and gas activities within the UKCS. As part of these regulations, any oil and gas company wishing to carry out a seismic survey must apply for consent from DECC. The Joint Nature Conservation Committee (JNCC) is consulted on whether consent should be granted for each individual seismic survey. A standard condition is that the JNCC guidelines for minimising the risk of disturbance and injury to marine mammals from seismic surveys (JNCC, 2010) are always followed. These guidelines require the use of trained Marine Mammal Observers (MMOs) whose role is notably to ensure that JNCC reporting forms are completed for inclusion in the MMO report. A pre-shooting search (visual assessment) should be conducted before commencement of any use of the airguns to determine if any marine mammals are within 500 metres of the centre of the airgun array (mitigation zone). In this case, the start of the seismic sources should be delayed. If seismic surveys are planned to start during hours of darkness or low visibility, Passive Acoustic
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Monitoring (PAM) should be employed. The start of the seismic sources should also be a soft- start: power should be built up slowly to give adequate time for marine mammals to leave the area. Those measures should thus ensure that significant negative impacts on marine mammals are avoided. There is evidence that underwater explosions for demolition and other purposes can kill substantial numbers of animals, such as fish (Tucker et al., 2008)23. Determination of these impacts has focused upon the mortality of adult fish, turtles, and marine mammals. For these animals, mortality can be predicted and abundance and distribution in the impact area can be determined with acceptable accuracy provided that fish abundance and distribution are known (Govoni et al., 2008). For example, one study calculated that with a 2.5 tonne (TNT equivalent) charge the mass of killed fish can amount to 20 tonnes during each explosion (Patin, 1999). But the sensitivity of larvae and small juveniles has not been adequately examined, and the abundance and distribution of young fishes is difficult to estimate. These impacts are much more hazardous for the fish stock. A study determined sensitivities of the larvae and small juveniles of two species of fish to shock wave exposure under experimental conditions24. A wide range of pressure were tested. Over the duration of the project, 0.14 – 1% of fish were lethally injured and 2-3% of the larvae in the system were killed. The authors estimated that it was unlikely to seriously affect fish at the population level (Govoni et al., 2008). Drilling rigs may contribute to impacts on some marine habitats and species as a result of the disturbance of benthic habitats (e.g. sediment burial, decompression, temperature change) and pollution due to drilling waste discharge (e.g. by particles), but there is little evidence that these have any population level impacts (Tucker et al., 2008). For example, a study analysed epibenthic megafauna before and after physical disturbance caused by the drilling of a hydrocarbon exploration well in the North Sea. Megafaunal density, in general, had declined one month after the drilling event. There were particular declines in the density of the numerically dominant echinoid, Echinus acutus var. norvegicus, in a 50 m zone around the drill site (Hughes et al., 2010). However, this impact at the population level has not been studied in a longer term. The other concern about drilling rigs is related to pollution by particles, which have two distinct impacts: physical burial of benthic communities, depending on the volume of sediment impacted by particle deposition, and an increased turbidity zone in the water column. On the one hand, some results showed that cutting particles contribute substantially to the total impact of offshore oil and gas production on marine sediments, with a relative contribution of 55% and 31% on the regional and global scale, respectively. On the other hand, the contribution of particulate emissions to the total impact on the marine water column is of minor importance. Therefore, particles are an important stressor in marine ecosystems, but mostly for marine sediment (Veltman et al., 2011).
23 This information is based on generic oil and gas activity. There is no clear evidence that underwater explosions are used in UK waters.
24 It should be noted that seismic activity (for oil & gas activity) is frequently restricted in areas and at times of known spawning or nursery activity.
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Gas flares from drilling rigs have also been known to attract and kill large numbers of migrant birds through collision (Sage, 1979; Wiese et al., 2001). However, the frequency and significance of these events is uncertain (Tucker et al., 2008).25 During oil extraction, a mixture of oil, water and gas is produced from reservoirs and these components are usually separated in the production train. The oil and gas is exported to shore while the produced water is disposed of in a number of ways, but most commonly discharged to sea. The produced water is treated to remove the majority of oil before being discharged to sea, but small volumes, within legal requirements, remain. The following table details oil- contaminated produced water discharges between 2005 and 2009 in the UK (DECC, undated). Table 5: Produced water discharges containing oil between 2005 and 2009
Water discharges 2005 2006 2007 2008 2009
Number of installations discharging oil in 107 105 101 96 98 produced water
Total produced water discharged (million m3) 235 219 203 198 197
Total dispersed oil in produced water 4968 4356 2960 3160 2900 discharged (tonnes)
Oil content (mg/l) 21.1 19.9 14.6 16.0 14.8
Number of installations re-injecting oil in 16 20 23 24 26 produced water
Produced water re-injected (million m3) 24.8 30.7 40.5 39.6 40.4 Source: DECC, undated
1.3.2.1 Oil and gas transportation – Hazrdous impacts Similarly, oil and gas transportation will cause oil and gas release in the environment in case of leak or rupture. The incident frequency of land pipelines has clearly decreased and is relatively small (IPCC, 2005). For gas pipelines, the incident frequency in Europe (moving average, past 5 last years) was around 0.9 per 1,000 km per year in 1974 and fell to around 0.2 per 1,000 km per year in 2010. These figures cover unintentional gas release from onshore pipelines made of steel, with a maximum operating pressure higher than 1.5 bar and located outside the fences of the gas installations such as compressor stations. These figures include many kinds of incidents, mainly leaks (pinhole/crack or hole) and ruptures. Most incidents occur on small pipelines, old pipelines,
25 This information is based on generic oil and gas activity. There is no clear evidence that such practices take place in UK waters.
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pipelines with a weak cover depth and pipelines with a weak wall thickness. External interference was the main incident cause between 2006 and 2010, due to external activities (e.g. digging, piling, ground works) and their equipment (e.g. anchor, bulldozer, excavator, plough), followed by corrosion and construction defect or material failure (EGIG Pipeline Incident Database Database 2011) For oil pipelines, the incident frequency in Europe (moving average, past 5 last years) was around 0.25 per 1,000 km per year in 2010. These figure cover oil pipelines, with a length of 2 km or more in the public domain, running cross-country (including short estuary or river crossings but excluding under-sea pipelines). They also cover pump stations, intermediate above-ground installations and intermediate storage facilities, but exclude origin and destination terminal facilities and tank farms. They cover incidents whose spillage size has been set at 1 m3 and more, unless exceptional safety or environmental consequences are reported for a lower spill. Like gas pipelines, the main incident causes between 2006 and 2010 were third party activities and mechanical failures, followed by corrosion (CONCAWE report 201126). The incident frequency of marine pipelines is also relatively small (IPCC, 2005). Dragging ships’ anchors causes some failures in shallow water (less than 50 m). Ships and objects sink or fall very rarely onto pipelines. Pipelines of 400 mm diameter and larger have been found to be safe from damage caused by fishing gear and smaller pipelines are trenched to protect them. Ship incidents are due to collision, foundering, fire or stranding, the latter being the main cause of tanker incidents. Tankers have generally higher standards than average ships. Liquefied natural gas (LNG) tankers are potentially dangerous, but carefully designed and generally operated to very high standards, so that there have been no accidental gas release from LNG ships. Indeed, the LNG tanker El Paso Paul Kaiser ran aground at 17 knots in 1979, and incurred substantial hull damage, but the LNG tanks were not penetrated and no gas was released (IPCC, 2005). Table 6: Oil and chemical releases from offshore installations and pipelines in the UK
Oil and chemical release 2005 2006 2007 2008 2009 2010
Total amount oil discharged (tonnes) 75.18 26.63 62.65 37.28 50.93 23.36
Total amount chemicals discharged (tonnes) 347 414 854 703 1,300 593
Number of oil discharges > 1 tonne 10 4 10 8 8 6
Number of chemical discharges > 1,000 kg 20 44 54 58 50 56
Number of oil discharges < 1 tonne 256 271 271 264 285 265
Number of chemical discharges < 1,000 kg 48 93 132 105 130 119 Source: DECC, undated
26https://www.concawe.eu/DocShareNoFrame/docs/1/GDMBIBKDGGLKEABJHCCAFDMBVEVCWY919YBYW3BYTKA3 /CEnet/docs/DLS/Rpt_11-5-2011-02743-01-E.pdf
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Oil releases may have some more significant impacts than gas on marine ecosystems and associated species when released into the marine environment, whether as accidental spills or chronic discharges. The risk is maximal near marine oil producing regions, along the main oil- tanker routes, and close to major petroleum handling facilities (ports, refineries, etc.). Notably, during the past few decades, intense research has been published on the impacts of polycyclic aromatic hydrocarbons (PAHs) in marine ecosystems. Their toxicity may be increased by chemical oil dispersants and by other compounds associated with the spill or generated during weathering processes under certain field conditions. Impacts occur through the uptake of dissolved hydrocarbons by aquatic organisms, which can lead to a wide variety of physiological responses. The impacts are complex because a range of processes, such as biodegradation, bioaccumulation, and biotransformation, will determine the bioavailability and toxicity of PAHs and other petroleum compounds. Moreover, there may be a great variability in the sensitivity of marine organisms to the same compound, even in the same taxonomic group. Chronic exposure to petroleum hydrocarbons can affect feeding, growth, development, and reproduction and cause irreversible tissue damage. For example, marine organisms such as filter feeding molluscs have an outstanding ability to bioaccumulate hydrocarbons in their tissues, whereas vertebrates readily metabolise and excrete them, although this process may create reactive intermediates with toxic effects. PAH exposure also induces reproductive and developmental impacts on fish, nonpolar narcosis and phototoxicity and has mutagenic, carcinogenic and cytotoxic potential, especially during embryogenesis and early stages of development. Eventually, PAHs alter the immune system of fish and other aquatic organisms. These impacts can cause damage in populations and communities, where they alter vital functions that affect the survival of organisms (Martínez-Gómez et al., 2010). For example, major incidents such as the spill from the Exxon Valdez, which led to chronic exposure of Alaskan coastal ecosystems, revealed unexpected persistence of toxic subsurface oil, although at sub-lethal levels, that had profound and long-lasting impacts on wildlife (Peterson et al. 2003). These effects have caused delayed population reductions and cascades of indirect effects, which have postponed ecosystem recovery. As a final impact, oil releases can result in the loss of large numbers of seabirds. However, there appears to be little evidence that such occasional incidents typically have long-term population impacts (Tucker et al., 2008). For example, Votier et al. (2005) showed that although four major oil spills doubled adult mortality in Common Guillemots (Uria aalgae) there was no significant effect on the number of individuals counted at the breeding colony (Votier et al., 2005), primarily as a result of increased recruitment of immatures to the breeding population (Votier et al., 2008).
1.3.2.2 Oil and gas transportation – Chronic impacts Regarding oil and gas transportation, the laying of new terrestrial and marine pipelines will induce habitat loss, fragmentation and degradation and fauna harm, mortality and disturbance. Buried marine and terrestrial pipelines may have greatest impacts regarding fauna mortality (e.g. benthic species, invertebrates), during construction as a result of indirect habitat loss or degradation due to changes in groundwater flows and soil layer mixing during digging and embankment, and high noise disturbance due to digging, etc. In contrast the main impacts of terrestrial aboveground gas pipelines are from habitat loss (Tucker et al., 2008). There is no
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equivalent to the terrestrial gas network for oil, since oil is mainly transported by tankers in marine areas. Although it has not been possible to quantify the area affected from marine and terrestrial pipelines, the proportions of habitats affected are clearly extremely low. Moreover, with appropriate routing to avoid sensitive sites most impacts will be on habitats of relatively low ecological value. Furthermore, rehabilitation of most impacted terrestrial habitats should be feasible. Thus pipeline impacts are unlikely to have any significant effect on the overall status of habitats and species, unless they are poorly sited and affect rare or localised biodiversity features. Potential mitigation measures The most important means of mitigating impacts is the avoidance of the most sensitive and important areas through, for example, thorough SEA and EIA, and Appropriate Assessments for projects affecting Natura 2000 sites. Regarding oil and gas transportation, preventative measures such as increasing the cover depth, using concrete barriers (e.g. casing, sleeves) above pipelines and warning tape can greatly reduce the risk of external interference. For example, increasing cover from 1 m to 2 m reduces the damage frequency by a factor of 10 in rural areas and by 3.5 in suburban areas (IPCC, 2005). Regarding tankers, their double hull requirement of the International Maritime organization (IMO) was adopted in 1992, following the Erika incident off the coast of France in December 1999. Moreover, IMO Member States discussed proposals for accelerating the phase-out of single hull tankers, so that all tankers have at least two hulls since 2010. Regarding oil spills, improved safety and clean-up measures appear to be reducing the frequency and impacts of major oil incidents. Chronic levels of oil pollution also appear to be declining, at least in some areas (Camphuysen, 1998).
1.3.2.3 Oil refining Oil refining impacts are mainly related to air emissions, wastewater and waste (Tucker et al.,
2008). Typical air emissions are exhaust gases (mainly NOx emissions), venting and flaring, fugitive emissions (e.g. from pipes, valves, seals, tanks and other infrastructure components) likely to lead to emissions of volatile organic compounds (VOC), sulphur oxides, particulate matter from point sources and GHGs. Wastewater impacts are related to industrial process wastewater and other wastewater streams and water consumption. Finally, oil refining leads to the production of spent catalysts and other hazardous wastes.
1.3.2.4 Oil and gas combustion
Total NOx and SO2 emissions from petrol fuels have decreased substantially in the past two
decades in the UK. In 2009, in the UK, petroleum fuels lead to the emission of 0.114 Mt of SO2
(2.516 Mt in 1970), i.e. about 29% of total SO2 emissions and of 0.608 Mt of NOx (1.384 Mt in
1970), i.e. about 56 % of total NOx emissions (Defra, 2011). Gas-fired electrical generating units
produce little SO2. In 2009, in the UK, gaseous fuels lead to the emission of 0.010 Mt of SO2
(0.019 Mt in 1970), i.e. about 3% of total SO2 emissions and of 0.231 Mt of NOx (0.098 Mt in 1970),
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i.e. about 21 % of total NOx emissions (Defra, 2011). The associated impacts on biodiversity are detailed in the section on coal.
1.3.3 International biodiversity impacts and their mitigation
In 2010, the UK imported crude oil mainly from Norway (67%), OPEC countries (15%) and Russia (8%); while natural gas was imported into the UK mainly from Norway (48%), Qatar (28%) and the Netherlands (15%) (DECC, undated). Therefore, the environmental impacts of oil and gas exploration, extraction and transportation will also occur there. New exploration and extractions techniques are being investigated because the current reserves are diminishing. These techniques may have specific negative impacts on biodiversity. Oil sands, also called tar sands or bituminous sands, comprise an unconventional deposit of oil characterised by high viscosity, high density, and high concentrations of nitrogen, oxygen, sulphur and heavy metals. These characteristics result in higher costs for extraction, transportation, and refining than with conventional oil. Despite their cost and technical challenges, major international oil companies have found it desirable to acquire, develop, and produce these resources in increasing volumes. They are reported in many countries, mostly in Canada, but also in Kazakhstan and Russia, which exports oil to the UK (World Energy Council, 2010). Oil sand extraction is considered to be more environmentally damaging than conventional oil extraction. Notably, it induces habitat loss over large areas and the creation of substantial amounts of toxic chemicals during the separation process that cause water and air pollution. Heavy metals such as vanadium, nickel, lead, cobalt, mercury, chromium, cadmium, arsenic, selenium, copper, manganese, iron and zinc are present in oil sands. Another innovative extraction technique is the deep-sea or ultra-deepwater drilling. It is the process of oil and gas exploration and production in depths of more than 400 m or 1,500 m for ultra-deepwater drilling (UK Parliament, undated). It has not been economically viable for many years, but with rising oil prices, more companies are investing in this area. This has led to several major environmental impacts, most notably from the Deepwater Horizon oil spill. This offshore drilling unit could operate in waters up to 2,400 m deep and drill down to 9,100 m. At the time of the explosion in April 2010, it was drilling an exploratory well at a water depth of approximately 1,500 m in the Macondo Prospect, located in the Gulf of Mexico. By April 2011, the resulting pollution is known to have killed 6,147 birds, 613 sea turtles and 157 mammals, and injured 3,046 birds, 536 sea turtles and 13 mammals (US Fish & Wildlife Service, undated). In the UK, to the west and north of Shetland, there are a number of fields and appraised prospects in water depths of up to 1,000 metres. There are also proposals to drill exploration and appraisal wells in water depths of up to approximately 1,500 metres. The UK Continental Shelf to the west of Scotland, which may be the subject of oil and gas exploration in the future, includes areas where the water depth is in excess of 3,000 metres (DECC, undated). Deep-sea drilling techniques are also used in countries that export oil to the UK.
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1.3.4 Conclusions
Summary of known impacts With proper implementation of appropriate mitigation measures overall biodiversity impacts from energy production from oil and gas are likely to be low. The main potential impacts are fish and marine mammal mortality from underwater explosions for demolition and seismic surveys, habitat loss and degradation as a result of the laying of pipelines (with significant impacts primarily on marine habitats) and disturbance of benthic habitats and low level chronic pollution associated with drilling rigs. Other potential impacts include oil and chemical dispersant pollution resulting from major oil spills, but their probability in UK waters is low and their potential impacts are variable and difficult to predict. However, the potential increase in deep water drilling may lead to increased risks to biodiversity, including catastrophic accidents that are difficult to deal with. Increasing demands for oil and gas and declining UK production are expected to increase imports, with consequential increased impacts on overseas biodiversity. Such impacts will be particularly high from supplies originating from oil sands, as there is good evidence that the extraction of oil from these sources has high environmental and biodiversity impacts. Knowledge gaps and required research There is generally good evidence on the impacts on biodiversity of oil and gas production. There are, however, some areas where knowledge is lacking, for example: the sensitivity of larvae and small juveniles to underwater explosions (making it difficult to estimate the abundance and distribution of young fishes). the long-term effects of drilling on populations has not been studied. the frequency and significance of bird fatalities due to collision with gas flares from drilling rigs. The potential impacts of the extraction of shale gas through fracking (which is not considered in this review).
Table 7: Summary of potential biodiversity impacts per unit of energy produced from the use of oil and gas for UK energy requirements
Selected Similar impacts of gas and oil Impacts specific to oil technology
Impacts in UK
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Selected Similar impacts of gas and oil Impacts specific to oil technology
Positive impacts None identified. None identified.
Direct mortality Low: mortality from attraction of birds to gas Impacts of oil spills on flares, fish and marine mammals mortality from marine and coastal underwater explosions for demolition and species. seismic surveys. Pollutants from drilling muds and water may be toxic to some species.
Direct habitat Low: Some marine and terrestrial habitat loss - loss from drilling and production structures and particularly pipelines, but normally insignificant, especially if terrestrial pipelines are buried.
Indirect habitat Low: Pollution impacts from rigs (drilling muds Variable, but potentially degradation and water, and wastes) on marine ecosystems high impacts from oil spills (and dispersant) on marine and coastal ecosystems.
Disturbance Moderate: Disturbance at sea from work on rigs, - demolition and seismic surveys. Lower level disturbance from pipeline construction, oil & gas extraction, transport, refining and storage.
Secondary Low / Moderate: Activities associated with port - impacts development.
Potential for Moderate: Avoidance of the most sensitive - mitigation habitats is important, but may not be feasible with respect to drilling rigs. Measures can be taken to reduce disturbance and pollutants, and rehabilitation of habitats should be feasible for most terrestrial pipelines.
OVERALL LOW from normal activities, but potentially RESIDUAL HIGH from oil spills IMPACTS
Potential for Variable: High for pipeline impacts on most - ecological terrestrial habitats (if fragile habitats and that compensation require long-time scales for restoration are
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Selected Similar impacts of gas and oil Impacts specific to oil technology
avoided). Opportunities for compensation for marine habitats are constrained, but it might be feasible for some habitats through protection and exclusion of bottom trawling.
Impacts outside the UK
Variable depending on source, location and Greater terrestrial drilling extraction technology: Offshore impacts similar and production impacts to UK, although deepwater drilling may be used in some countries, more, with associated higher accident risks. especially where oil supplies are extracted
from oil sands.
1.4 Carbon capture and storage (CCS)
1.4.1 Overview of the technology
Fossil fuels used for energy includes oil, coal and gas. These are traditionally burnt in air, their combustion driving a steam engine but leading to greenhouse gas emissions by exhaust gas. A majority of UK electricity is produced in plants burning those fuels.
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Figure 5: Principle of Carbon Capture and Storage
Source: ©CO2CRC Carbon Capture and Storage (CCS) is a mitigation technology that comprises capturing and storing carbon dioxide that would otherwise be emitted to the atmosphere by fossil-fuel burning power stations (i.e. oil-fired, coal-fired or gas-fired power plants). CCS involves capture of CO2 which is then compressed and transported via pipelines and injected to be stored, onshore or offshore, in secured sequestration sites such as depleted oil and gas reservoirs or deep saline aquifers, where it is meant to remain trapped. The technology is considered by experts as being well understood and is currently in use in selected commercial applications (in a favourable tax regime or a niche market, due to current high costs), though not at as large a scale as would be required for a power station. It can be roughly divided into three significant steps: capture, transportation and storage (Figure 5). Capture Capturing the carbon dioxide from an existing fossil-fuel burning power plant is referred to as post-combustion capture: after the fuel (oil, gas or coal) is burnt in air in a furnace (this burning will heat water in a boiler, producing steam that will in turn activate a turbine and produce electricity –see Figure 6), the low-pressure exhaust gases from the combustion (currently emitted to the atmosphere) are passed through a separation process: solvent absorption (where CO2 is absorbed from a gas stream directly into a liquid, generally an amine), adsorption (where it is adsorbed from a gas stream on the surface of a solid, generally a mineral zeolite or a carbon nanocage), filtration by a membrane (polymers or ceramics that sieve out the carbon dioxide molecules from the gas stream) or cryogenic techniques (which cools and condense carbon dioxide from the gas stream at low temperatures). Post-combustion facilities can be retrofitted to existing power plants or provided as a feature of new plants in the future.
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Another approach to post-combustion CCS is oxy-firing (or oxyfuel) combustion, in which the fossil fuels are burnt in an artificially created oxygen atmosphere instead of air. The flue gas emitted then is highly concentrated in carbon dioxide and only requires water vapour to be removed (by cooling and compressing the gas stream). Contrary to post-combustion capture, oxy-firing requires changes to the boiler and associated flue-gas handling systems to accommodate the higher flame temperatures resulting from combustion with oxygen. This has not yet been shown to be economically feasible. Figure 6: Principle of a traditional fossil fuel power plant
Source: tva.com/power/coalart.htm Figure 7: Principles of post-combustion capture (left) and oxy-firing capture (right)
Source: ©CO2CRC
Available technology captures about 85-95% of the CO2 emitted in a CCS plant, but capture and compression of a CCS system roughly need 10-40% more energy than a plant of equivalent output without CCS. Overall, a power plant with CCS could reduce its CO2 emissions to the atmosphere by approximately 80-90% compared to a plant without CCS27 (Figure 8). For a similar
27 IPCC 2005, Carbon Dioxide Capture and Stroage, Summary for Policymakers, p4 http://www.ipcc.ch/pdf/special-reports/srccs/srccs_summaryforpolicymakers.pdf
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energy output, installation of CCS equipment would imply a larger water boiler (since the plant resource requirement is increased) but no significant new facilities in the case of post- combustion capture.
Figure 8: CO2 emission and capture in power plants with and without CCS technology
Source : IPCC 2005 Transport Carbon dioxide is then compressed from atmospheric pressure to supercritical state (i.e. in a phase between gas and liquid), and transported from its source to the storage site through buried or exposed pipelines. Offshore or onshore CO2 pipelines are generally buried over most of their length, to a depth of 1-1.2 meters, and their diameter can vary greatly. The length depends on the distance between the source and the injection point on the storage site, which can be chosen to minimize that distance. To keep carbon dioxide in a supercritical state along the transport distance, booster pumps may be needed. Storage Storage can take place in depleted oil and gas reservoirs or in saline aquifers (deep geological formations consisting of permeable rocks that are saturated with salt water). Supercritical CO2 is injected by a pump into the reservoir at a pressure greater than that of the reservoir fluid pressure, but not so great as to fracture the formation. An injection well takes up an area about 10 m wide by 20 m long (including a safety perimeter). Possible storage sites need to be selected by country-wide screening of sedimentary basins which have the potential to store CO2 in a pore space in rock (such as limestone and sandstone) or via adsorption onto coal, and which present an impermeable caprock to prevent CO2 from escaping to the surface. It can also be envisaged in deep ocean or in oil reservoirs for EOR (Enhanced Oil Recovery).
Concerns about storage are whether this technology can prevent CO2 leakage to the surface, knowing that it would make the technology useless in terms of CO2 emissions reduction, and that
CO2 is an asphyxiant. Estimates from the IPCC are that risks are low provided the storage site is
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carefully chosen. Special care must also be taken when injecting the supercritical CO2 into the reservoir, as overpressure may cause rock fracking.
1.4.2 Use in the UK
The CCS technology is currently at an early phase in the UK: negotiations held for the first proposed CCS demonstration project at Longannet power station (Scotland) have concluded and the project will not proceed. It is, however, implemented in the pilot power plant Schwarze Pumpe (Germany), on a 30 MW oxy-fuel coal-fired station. However, the UK Government has set out plans for demonstration and future deployment of CCS: a policy requiring that all new coal plants demonstrate the full CCS chain (capture, transport and storage) on at least 300 MW net of their total output has been introduced. These plants are then expected to retrofit CCS to their full capacity by 202028. Indeed, in 2010, 40.3% of the electricity supply was generated from natural gas, 32.2% from coal 29 and 1.5% from oil . The burning of those fossil fuels emitted 185.8 Mt of CO2e in 2010, which represents 91% of all emissions from energy supply in the UK. While the UK has obligations to cut its greenhouse gas (GHG) emissions by 80% in 2050 against a 1990 level, a complete abandonment of fossil fuels would risk compromising its ability to meet energy demand given their current prevailing status as energy sources. Deploying CCS is considered a way to maintain fossil fuels within the energy mix while ensuring GHG emissions reductions, but does not address the issue of UK’s dependency on fossil fuels: in 2010, 59% of the coal used was imported -mainly from Russia (9.8 Mt), Colombia (6.4 Mt) and the US (4.54 Mt), as well as 38% of the natural gas used -mainly from Norway (25 bn m3 via the 1,173 km long Langeled pipeline, see Figure 9) and Qatar (14.6 bn m3).
28 DECC 2010, CO2 Storage in the UK – Industry Potential http://www.decc.gov.uk/assets/decc/What%20we%20do/UK%20energy%20supply/Energy%20mix/Carbon%20captur e%20and%20storage/1_20100317090053_e_@@_UKStorageIndustryPotentialSeniorCCS.pdf 29DECC 2011, The Energy Statistics, p117. http://www.decc.gov.uk/assets/decc/11/stats/publications/dukes/2307-dukes-2011-chapter-5-electricity.pdf
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Figure 9: Langeled pipeline running from Nyhamna (Norway) to Easington (UK)
Source: pipeliner.com Fossil fuels are still produced in large quantities in the UK: coal mines generated a total output of 18.4 Mt of coal (representing 41% of coal consumption) in 2010 and are scattered around the territory. The production of gas amounted to 55 bn m3 (62% of supply) and has a 520 bn m3 estimated reserve (including proven and probable), while oil fields produced a 63 Mt output and still have a 751 Mt estimated reserve. Source: DECC
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Figure 10: Oil and Gas fields in the UK
Source: aapg.org The UK Climate Change Committee30 states that the UK has storage assets making CCS relevant if it is shown to be economically viable: it is suggested that practical UK CO2 storage capacity in depleted oil and gas fields alone might total 3,500 MtCO2 by 2030, equivalent to about 30 years of output from nearly 20 GW of coal-fired plants operating at 75% capacity factor31 (or at least 40 GW of gas-fired plants, due to lower carbon-intensity of gas). The theoretical storage capacity within saline aquifers is likely to be considerably larger: research estimates that Scotland’s available storage capacity within saline aquifers is in the range 4,600 to 46,000 Mt CO2. Further research is required to identify potential reliable storage sites but it is foreseen that full-scale CCS projects will ultimately be clustered around the CO2 clusters of emissions (there are four of those emissions centres in the UK: the Firth of Forth in Scotland, and the Humber, Teesside and 32 Thames estuary in England) to minimize the transport length . Figure 11 shows a potential CO2 storage network using shared infrastructure (to help reduce the costs per tonne to transport and store CO2) storing CO2 in saline aquifers formations in the Central North Sea.
30 Committee on Climate Change, 2011, The Renewable energy review, pp 52-53. http://hmccc.s3.amazonaws.com/Renewables%20Review/The%20renewable%20energy%20review_Printout.pdf 31The capacity factor is the ratio expressing the actual energy output of power plant over a period of time and its output if it had operated at full installed capacity the entire time. 32 Scottish Government, 2009, Review of Generation technologies, http://www.scotland.gov.uk/Publications/2009/12/10134807/6
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Figure 11: Prospective scenario for a CCS storage network in the Central North Sea
Source: the Scottish Government
1.4.3 UK biodiversity impacts and their mitigation
1.4.3.1 CO2 capture Potential impacts
Up to now, no CO2 capture facilities exist in the UK. The construction of CO2 capture facilities would not necessarily consist in new plants: they can be added to existing power plants or provided as a feature of future power plants. In these two cases, the construction and operation
of CO2 capture facilities would have additional impacts on biodiversity, occurring mainly in the UK since UK electricity imports represent only 2% of UK electricity supply.
The work for the construction of CO2 capture facilities would cause impacts similar to most terrestrial facilities constructions. It would cause temporary loss or degradation of habitats on the construction footprint, both directly (e.g. forest loss due to tree removal) and indirectly (e.g. wetlands degradation due to change in water flows). It would also cause temporary fauna harm
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or mortality on the construction footprint, both directly (e.g. invertebrate harm or mortality due to soil excavations) and indirectly (e.g. aquatic species harm or mortality due to pollution by solvents). It would eventually cause temporary fauna disturbance through noise, vibrations and artificial lighting on an area larger than the construction footprint.
The impacts on biodiversity of the operation of CO2 capture facilities would depend largely on
the CO2 capture process and the additional energy required. Indeed, the latter increases the flows of fuel, chemicals and some emissions required for the generation of a megawatt hour of electricity with global indirect impacts on biodiversity (IPCC, 2005).
CO2 capture facilities produce a stream of concentrated CO2 for storage, in most cases gas emitted to the atmosphere, liquid wastes (e.g. cooling water) and in some cases solid wastes (IPCC, 2005). All these outputs may have global indirect impacts on biodiversity, depending on their quality and quantity. Potential mitigation measures
The impacts on biodiversity of the construction of CO2 capture facilities may be avoided and minimised through planning on the spatial location, the timing of work, the techniques used, etc.
1.4.3.2 CO2 transport through land or marine pipelines Potential impacts
Since no CO2 pipelines currently exist in the UK, the construction and operation of CO2 pipelines would have additional impacts on biodiversity, occurring in the UK, between the existing or
future power plants and coast for land pipelines or between coast and offshore future CO2
storage sites for marine pipelines. Indeed CO2 storage would mainly be offshore in the UK.
The construction and operation of CO2 pipelines would have impacts on biodiversity similar to natural oil and gas pipelines, except for pollution due to occasional leak or rupture (IPCC, 2005).
Occasional leak or rupture of CO2 pipelines would cause direct temporary degradation of habitat, marine or terrestrial, and harm or mortality of fauna, but the associated ecological impacts have yet to be assessed.
Moreover, impurities may be captured with the CO2 stream in the power plant: the major ones
are well known (SO2, NO, H2S, NO2, H2, CO, CH4, N2, Ar and O2) but there is little published information on potential trace impurities such as heavy metals in the feed gas. The types and
concentrations of impurities depend on the CO2 capture process and the power plant design. If
impurities, particularly H2S, are contained in the CO2 stream, the impacts of leak or rupture of
CO2 pipelines on biodiversity could be increased (IPCC, 2005).
Regarding land CO2 pipelines, unlike oil and gas, CO2 is not flammable or explosive with air (Gale and Davison, 2004), so that the risk of direct loss or degradation of habitat is reduced. Scarce
information has been found on ecological impacts of marine CO2 pipelines leaks. However, we can assume that they will be similar to those occurring in the case of release from offshore storage sites (see below). The incident frequency of land pipelines has clearly decreased and is relatively small (IPCC, 2005).
For CO2 pipelines, 10 incidents occurred between 1990 and 2001 in the USA, which corresponds
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to an incident frequency around 0.32 per 1,000 km per year. The incident causes were relief valve failure (4 incidents), weld/gasket/valve packing failure (3), corrosion (2) and outside force (1). Unlike oil and gas pipelines, outside force was not a main incident cause (Gale and Davison, 2004). The incident frequency of marine pipelines is relatively small (IPCC, 2005). Dragging ships’ anchors causes some failures in shallow water (less than 50m). Ships and objects sink or fall very rarely on to pipelines. Pipelines of 400 mm diameter and larger are generally safe from damage caused by fishing gear and smaller pipelines are trenched to protect them. Most incidents result from human error in trenching and monitoring (Palmer and King, 2004). Potential mitigation measures
For CO2 pipelines, preventative measures may address their mechanical quality (e.g. material, thickness). Other preventative measures such as increasing the cover depth, using concrete barriers (e.g. casing, sleeves) above pipelines and warning tape can greatly reduce the risk of leak or rupture due to outside force. For example, increasing cover from 1 m to 2 m reduces the damage frequency by a factor of 10 in rural areas and by 3.5 in suburban areas (Guijt, 2004).
1.4.3.3 CO2 transport through tankers Potential impacts
CO2 can be transported by tankers in a liquefied form. Up to now, no CO2 transport through
tankers exist in the UK. Therefore, the operation of CO2 tankers would have additional impacts
on biodiversity, occurring in the UK, between coast and the future offshore CO2 storage sites.
CO2 transport through tankers may cause permanent direct mortality of some aquatic species such as marine mammals due to collisions. They may also cause permanent fauna disturbance through noise, vibrations and artificial lighting on their trajectory.
CO2 transport through tankers may also cause occasional CO2 release, resulting in air, water and seabed pollution (see above). This would cause direct habitat loss or degradation and aquatic fauna harm or mortality. Tankers have generally higher standards than average ships. Ship incidents are due to collision, foundering, fire or stranding, the latter being the main cause of
tanker incidents. Unlike gas and oil, CO2 tankers rupture have reduced fire risk but the CO2 emissions resulting from an incident would be similar to the combustion during fire on an oil or
gas tanker. Liquefied CO2 gas releases onto the surface of the sea are anticipated not to have the
long-term environmental impacts of oil spills. CO2 would also behave differently from Liquefied
natural gas (LNG), because liquid CO2 in a tanker is not as cold as LNG but much denser. Its interactions with the sea would be complex: hydrates and ice might and temperature differences
would induce strong currents. Some of the CO2 gas would dissolve in the sea, but some would be
released to the atmosphere. If there were little wind and a temperature inversion, clouds of CO2 gas might lead to asphyxiation. However, consideration of such an event is a knowledge gap that requires further research (IPCC, 2005). Potential mitigation measures
The risk of CO2 tankers rupture (e.g. due to collision or stranding) can be minimised by careful planning of routes, careful navigation, rigorous standards of operation and high standards of
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training and management. However, the ship traffic will increase due to the CO2 reduction
policies, and the advantages of shipping compared to road and air in terms of CO2 emissions. This
increase would be heightened by additional CO2 tankers traffic, so that the effectiveness of planning would be limited. It can also be reduced by making certain that the high standards of construction and operation currently applied to liquefied petroleum gas (LPG) and LNG are also
applied to CO2 (IPCC, 2005).
1.4.3.4 CO2 storage Potential impacts
Up to now, no CO2 storage sites exist in the UK. It is expected that the majority of UK CO2 storage will occur underneath the North Sea (Gibbins, 2009). Indeed, the southern North Sea
Basin lies to the east of England and has a huge potential for CO2 storage. It contains three major reservoir rocks: the Bunter Sandstone Formation, the Leman Sandstone Formation and
Carboniferous sandstones. The potential for storing CO2 in the Bunter Sandstone Formation and the southern North Sea gas fields has already been studied (Benthman, 2006). Several scenarios, using a different rationale for choosing storage sites have been described. For example, the scenario Fossilwise I aims to use available storage space in gas fields. This is a ‘risk averse’ strategy due to the larger amount of available data and greater confidence in storage security of gas fields (they originally retained gas for millions of years and therefore they are likely to be able
to retain CO2). This would require the construction of a pipeline from the Bacton terminal on the coast to serve all the gas fields. Three offshore sites in this area are candidate as Special Areas of Conservation: "Inner Dowsing, Race Bank and North Ridge", "Haisborough, Hammond and Winterton" and "North Norfolk Sandbanks and Saturn Reef". The habitats of the Annex I of the Habitats Directive that are a primary reason for selection of these sites are "reefs" and "sandbanks which are slightly covered by sea water all the time" and would be affected by the
CO2 pipeline and storage site.
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Figure 12: Map of the Fossilwise I scenario
Source: Benthman, 2006
The environmental impacts arising from CO2 geological storage may be local environmental effects or global effects. Global effects address the uncertainty in the effectiveness of CO2 storage and the potential release to the atmosphere. Local environmental effects arise from three distinct causes: the direct effects of elevated gas-phase CO2 concentrations in the shallow subsurface and near-surface environment, the effects of dissolved CO2 on groundwater chemistry and the displacement of fluids due to the injected CO2 (IPCC, 2005).
CO2 storage sites would presumably be designed to confine all injected CO2 for geological time scales. Nevertheless, experience suggests a small fraction of storage sites may release CO2 to the atmosphere. No existing studies systematically estimate the probability and magnitude of release across a sample of credible geological storage systems. For large-scale operational CO2 storage projects, assuming that sites are well selected, designed, operated and appropriately monitored, the balance of available evidence suggests the following. It is very likely the fraction of stored CO2 retained is more than 99% over the first 100 years. It is likely the fraction of stored
CO2 retained is more than 99% over the first 1,000 years (IPCC, 2005).
Available technology captures about 85-95% of the CO2 emitted in a CCS plant, but capture and compression of a CCS system roughly need 10-40% more energy than a plant of equivalent output without CCS. A power plant with CCS could reduce its CO2 emissions to the atmosphere by approximately 80-90% compared to a plant without CCS (IPCC, 2005). This consists in a positive impact on the environment and indirectly on biodiversity compared to a plant without
CCS. But in case of CO2 release, mainly during transport or storage, this positive impact would be limited. Supposing that all the CO2 contained in a storage site would be released in the atmosphere, the final concentration in the atmosphere would be increased compared to a plant
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without CCS, because of the additional energy needed by CCS. This would result in a negative impact on the environment and indirectly on biodiversity.
Stored CO2 and impurities may also have local environmental effects, affecting the species with which it comes into contact. Impacts might be expected on microbes in the deep subsurface and on plants and animals in shallower soils and at the surface (IPCC, 2005). In the last three decades, microbes dubbed ‘extremophiles’, living in environments where life was previously considered impossible, have been identified in deep saline formations (Haveman et al., 2001), oil and gas reservoirs (Orphan et al., 2000) and sediments up to 850 m below the sea floor (Parkes et al., 2000). Unless there are conditions preventing it, these microbes may be found everywhere at the depths being considered for CO2 storage and consequently may be affected by injected CO2. The effect of CO2 on deep subsurface microbial populations is not well studied. A low-pH, high-CO2 environment may favour some species and harm others. For example, in strongly reducing environments, the injection of CO2 may stimulate microbial communities that would reduce the CO2 to CH4, while in other reservoirs, CO2 injection could cause a short-term stimulation of Fe(III)-reducing communities. Release from offshore storage sites may pose a hazard to benthic environments and organisms as the CO2 moves from deep geological structures through benthic sediments to the ocean.
Dissolved CO2 may also have environmental effects on aquatic life in the water column. However, the seabed and overlying seawater can also provide a barrier, reducing the release of CO2 to the atmosphere. No studies specifically address the environmental effects of release from sub- seabed geological storage sites.
If impurities are captured with the CO2 in the power plant stream, their net emissions of these impurities to the atmosphere will be reduced, but impurities in the CO2 may be stored along with
CO2 and result in environmental impacts (IPCC, 2005). Indeed, H2S is considerably more toxic than CO2. Similarly, dissolution of SO2 in groundwater creates a far stronger acid than CO2. For example, at Weyburn, one of the most carefully monitored CO2 injection projects and one for which a considerable effort has been devoted to risk assessment, the injected gas contains approximately 2% H2S (Wilson and Monea, 2005). To date, most risk assessment studies have assumed that only CO2 is stored. There has not been a systematic and comprehensive assessment of how these impurities would affect the risks associated with CO2 storage.
CO2 storage would also cause indirect loss or degradation of habitats and fauna harm or mortality through hazards to groundwater from CO2 leakage and brine displacement and induced seismicity. Eventually, noise and vibrations would be emitted during drilling and then permanently at the injection station, inducing permanent aquatic and benthic fauna disturbance. Potential mitigation measures From an operational perspective, creation of biofilms may reduce the effective permeability of the storage sites (IPCC, 2005). Preventative measures would also be a thorough assessment of the fraction retained for geological storage projects. It must be highly site-specific, depending on the geological characteristics of the selected storage site, the storage system design, the injection system,
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related reservoir engineering and the methods of abandonment, including the performance of well-sealing technologies.
1.4.4 International biodiversity impacts and their mitigation
Potential impacts Since most of the CCS process (power plants, transportation and storage) would occur in the UK
or near UK, the international impacts of CCS on biodiversity would only be related to the CO2 concentration in the atmosphere. Potential mitigation measures Preventative measures would also be a thorough assessment of the fraction retained for geological storage projects.
1.4.5 Conclusions
Summary of known impacts Comparing power plants with and without CCS, the main additional negative impact of CCS is
related to the necessary construction of new facilities: the CO2 storage facilities and CO2 pipelines. The main impacts are therefore likely to comprise temporary and permanent habitat
loss and the loss of associated species. Wider impacts may result from leakage of CO2 and other pollutants and their indirect impacts on benthic habitats and marine ecosystems. On the other
hand, if CO2 releases do not occur, there would be positive indirect impacts on biodiversity due to
the decrease in CO2 concentration in the atmosphere. Comparing power plants with CCS and other low carbon energies, it is important to include the biodiversity impacts of fossil fuels (oil, gas or coal) used, as described above. Knowledge gaps and required research There are many uncertainties regarding the impacts on biodiversity of CCS. The major ones
concern the potential heavy metals captures along with CO2 during CO2 capture process in power plants and the impacts on underground microbes, terrestrial fauna and flora and aquatic and
benthic fauna in case of CO2 release during transport and storage. Table 8: Summary of potential biodiversity impacts per unit of energy produced from the use of fossil fuels with carbon capture and storage for UK energy requirements
Selected Carbon capture and storage technology
Impacts in UK
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Selected Carbon capture and storage technology
Positive impacts None identified, besides limiting CO2 emissions which cause global warming and have impacts on biodiversity.
Direct mortality Low: Occasional pollution incident due to leak or rupture of CO2 pipelines or tankers.
Direct habitat loss Low: Construction of CO2 capture facilities.
Indirect habitat Uncertain: Leakage of CO2 and other pollutants could have indirect degradation impacts on benthic habitats and marine ecosystems.
Disturbance Low: Some disturbance construction of CO2 capture facilities,
construction of CO2 pipelines or transport via tankers.
OW None likely
Potential for Moderate: The impacts on biodiversity of the construction of CO2 mitigation capture facilities may be avoided and minimised through planning on the spatial location, the timing of work and the techniques used, Pipelines can be designed to reduce the risk of leak or rupture. The risk of rupture of CO2 tankers (e.g. due to collision or stranding) can be minimised by careful planning of routes, careful navigation, rigorous standards of operation and high standards of training and management.
OVERALL UNCERTAIN RESIDUAL IMPACT
Potential for Low: It would probably be possible to compensate for habitat loss CCS ecological from plants but not marine ecosystem impacts from CO2 and pollutant compensation leakage.
Impacts outside the None expected UK
1.5 Hydroelectric power
1.5.1 Overview of the technology
Hydropower generation uses the gravitational force and energy of falling or flowing water to produce electricity. It comprises of either using the potential energy of stored water, through the construction of dams, or the employment of the kinetic energy of a river to drive a water turbine
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and generator, producing electricity. Hydroelectricity is the most widely deployed renewable technology worldwide, accounting for roughly 16 per cent of global electricity consumption and 3,427 TWh of electricity production in 201033. Once the construction of hydroelectricity generation facility is complete, it produces no waste or carbon emissions during electricity generation. Historically, most hydropower schemes in the UK have been large-scale impoundment schemes comprising a dam-created reservoir, pipeline and power station (Young and Cane, 2004). Such large schemes can produce substantial amounts of power, typically over 20 MW in the UK and their storage gives the advantage of offering greater flexibility in the timing of water releases allowing power generation to match peak in demand. However, the schemes are very costly and have large environmental footprints and consequently the use of large reservoirs has become increasingly unpopular in Europe (IEA, 2010), with instead an increasing emphasis being placed on small or micro hydro run-of river schemes. Such schemes do not create a large reservoir, but comprise an intake, weir and headpond (with little or no storage capacity), penstock (pipeline) to transport water to the powerhouse where the turbine(s) is located and a tail race which returns the water to the river. Typical small schemes generate between 500 kW and 5 MW (Young and Cane, 2004). The majority of run-of river schemes are high head schemes in Scotland, although some low head schemes are being developed on wider higher flow rivers in the lowlands (e.g. a 300 kW scheme at Romney Weir on the River Thames34). Micro hydro projects are typically very small off-grid installations utilising existing weirs and mill races, with up to 100kW installed capacity. As they use existing structures they have very little if any new environmental impacts and are therefore not considered further in this study.
1.5.2 Use in the UK
The total hydroelectric installed capacity in the UK in 2010 was approximately 1,650 MW, which is 1.8% of the current total UK generating capacity and 18% of renewable electricity generation capacity35. The majority of this power is derived from large-scale schemes in the Scottish Highlands, 10 of which are over 20 MW36. As a consequence of having already exploited the most cost-effective sites and given the environmental concerns related to large scale hydropower generation, opportunities for the development of large hydropower schemes on the scale seen in the past are limited. The 100 MW (1.2 km2 reservoir) Glendoe is the only new large-scale scheme in the last 40 years37, but SSE have developed options for four new hydroelectric schemes38 in the
33 http://vitalsigns.worldwatch.org/vs-trend/global-hydropower-installed-capacity-and-use-increase
34 http://sepengineering.com/index.php?option=com_content&view=article&id=20:romney-weir-on-the-river- thames&catid=6:projects&Itemid=9
35 https://www.gov.uk/harnessing-hydroelectric-power
36 Highlands - Clachan, Cruachan, Sloy, Errochty, Glendoe, Glenmoriston, Inverawe, Lochaber, Rannoch, Tummel; Lowlands - Glenlee,Kendoon, Tongland
37 http://www.sse.com/Glendoe/HydroPower/
38 http://www.sse.com/WhatWeDo/AssetsAndProjects/
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Scottish highlands at Kildermorie (7.5 MW new reservoir), Choire ghlais/Lochaber (600 MW reservoir & pumped storage39), Chonais (3.5 MW run of river), Chaorach (2MW run of river) and at Balmacaan (600 MW pumped storage). The main potential for developing domestic hydropower in the UK therefore rests with a significant small hydropower resource on existing weirs and disused mills. Recent studies estimate there is a remaining viable hydro potential of 850-1550 MW in the UK, representing approximately 1-2 per cent of current UK generating capacity (DECC, 2012a). The actual installed capacity is nevertheless unlikely to reach the maximum remaining potential. Of the approximately 1,178 MW of unused hydro potential estimated to be left in England and Wales, the future use of hydropower will likely be limited to generation with an installed capacity of no more than 580 MW (Environment Agency, 2010). The Government’s National Renewable Energy Action Plan (DECC, 2010b), envisages a central scenario for hydro that envisages between 40 MW and 5 0MW a year being installed annually up to 2020, substantially greater than current rates of instalment. However, the need for additional pumped storage capacity could be a greater driver of hydroelectric capacity expansion. New projects include Balmacaan & Choire ghlais (see above) in the Scottish highlands. Table 9: Total installed capacity and gross electricity generation from hydropower in the UK in 2010
MW GWh Number of installations
< 1 MW 70 229 Scotland: 126; Wales – 50; England – 149; NI – 15
1 MW – 10 MW 193 580 Scotland – 58; Wales – 3; England - 3
> 10 MW 1,386 3,981 Scotland – 37; Wales – 6
Total 1,648 4,790 Source: (DECC, 2011), http://www.british-hydro.org/installations/installations.html
1.5.3 UK biodiversity impacts and their mitigation
Potential impacts By using the gravitational force of falling or flowing water- both of which are abundant and free – hydropower provides a source of power that is essentially emissions-free. However, when the life-cycle assessment of the hydro generation is conducted a wide range of associated GHGs emissions has been identified (Raadal et al, 2011). Moreover, there are significant environmental impacts that the dams and reservoirs can have on ecosystems and biodiversity through the flooding of habitats above impoundments and downstream disturbance of the natural flow of rivers (McAllister et al, 2001). Such UK schemes have substantially increased the area of open- water habitats, especially in the uplands, which has benefited some species, such as some
39 http://www.bbc.co.uk/news/uk-scotland-highlands-islands-20128316
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aquatic plants and invertebrates, fish and waterbirds. However, many of these artificial reservoirs have destroyed natural and semi-natural habitats of greater ecological value, including upland rivers, heathland, woodland and bogs, together with their specialist species. Furthermore, impounded reservoirs tend to be dominated by deep water that limits their value for benthic fauna. The fluctuating water levels of reservoirs and wave action over their large open areas inhibits the development of marginal vegetation, resulting in bare margins with limited ecological value. Downstream impacts of large impoundments schemes can include major and sudden changes in flow patterns. This can have profound effects on the river community for long-distances downstream, especially for sensitive species such as bryophytes, Atlantic Salmon (Salmo salar) and freshwater pearl mussel (Margaritifera margaritifera). Also, large dams prevent upstream movements of fish, which is of particular concern for migratory diadromous species (fish that travel between salt and freshwater), including include Salmon, Eel (Anguilla anguilla), Allis Shad (Alosa alosa), Twaite Shad ( Alosa fallax) and Lamprey (Petromyzon marinus). The impacts of smaller scale run-of river hydro schemes are much lower than those involving large impoundments and reservoirs. Nevertheless, poorly designed run-of river schemes can pose a significant threat to fish populations and other aspects of riverine ecology because they can cause mortality of fish in turbines, restrict movement of migratory species and result in reductions in river flows. On the other hand, in the UK, small-scale hydropower is usually sited where there is already sufficient height to provide a hydropower opportunity (i.e. an existing weir or waterfall) and do not result in the creation of new impoundments (Environment Agency, 2010). These sites may already be a barrier to fish passage, in which case the siting of small-scale hydropower with fish passes may result in improved fish passage (British Hydropower Association and IT Power, 2010). The impacts of small-scale hydropower are dependent on where the sites are located, the type of instalment, the effectiveness of mitigation efforts to maintain flows and allow fish passage, and the cumulative impact of hydropower instalments over a river’s length. A considerable concern associated with the development of hydropower stations is the loss of connectivity for diadromous and other migratory species. Studies of salmonid populations show significant effects on genetic diversity through natural and artificial barriers to upstream fish movement (Neville et al, 2006). Responses to genetic isolation include reduced population viability due to the effects of inbreeding and genetic drift, increased susceptibility to disease, reduced ability to adapt to changing pressures and reduced breeding success (reduced effective population size). The impacts hydropower stations have on the migrations of the fish downstream is also considerable. The ecological impacts mainly relates to various form of stress fish are exposed to when passing through hydraulic turbines, often leading to fish mortality (Larinier, 2008). Even with a low mortality rate the cumulative effects of a series of hydroelectric power plants located on the same river might pose a threat to entire populations. Spillways and weirs can usually provide a safe means to pass the dams, given that fish are able to fall safely, there is sufficient depth and there are no damaging baffles at the base of the dam.
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Cumulative impacts The effectiveness of fish passes to mitigate the impacts of fish mortality are considered below. Nonetheless, experience shows that even obstructions fitted with effective fish passage facilities cause a delay in migration, and therefore successive hydropower installations have a cumulative impact. Larinier (2008) concludes that it is not good management to construct more than a very limited number of small-scale hydropower stations on rivers where there is a policy to protect migratory species. If the aggregate environmental impacts per unit of electricity production are considered, the advantages of small scale hydropower diminishes given that a large number of individual small run-of-river hydropower projects built along one river might well have the same or an even greater cumulative impact than one very large reservoir project (Abbasi and Abbasi, 2011, Egré and Milewski, 2002). Whether many small hydro plants are less ecologically damaging than comparatively fewer but larger hydro plants, can only be answered on a case by case basis taking into consideration the interaction effects of other anthropogenic pressures (Keder and McIntyre Galt, 2009).
Potential mitigation measures As with other technologies the appropriate siting of the energy technology is usually the most effective means of avoiding and reducing impacts. In the case of hydropower, it is best considered within a broader water management and ecosystems approach that integrates the uses of land, water and resources to promote sustainability within natural hydrological boundaries of water basins. This is advocated in the European Water Framework Directive and also the European Flood Risk Management Directive, for example, promoting the principle of integrating objectives in management schemes that encompass the area of land drained by a river and its tributaries (Biesbroek et al, 2009). The appropriateness of locating hydropower schemes on sensitive rivers containing species of high conservation value is especially important and is therefore taken into account in the UK, e.g. through the classification of rivers into sensitivity categories. The Environment Agency (2010) considers that rivers in England and Wales are highly sensitive where there is a high chance of diadromous species being present. Other sites are classified as medium or low sensitivity according to the probability that mobile or migratory species are present. Under a scenario of full usage of the England and Wales capacity (1.2 GW or 25,935 sites), 46% of identified sites were classified as highly sensitive, 26% as medium or low and the remaining 28% unknown (Table 10).
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Table 10: The number of possible future hydroelectricity sites in England and Wales classified according to their potential fish impacts
West Midlands West
East Midlands East Sensitivity with and Yorkshire Total
the the
South West
North West
South East respect to East North
England
Humber potential impacts of East
Wales on fish species
Unclassified 285 729 301 1,460 832 888 645 1,106 926 7,172 28%
Low 278 128 1 145 358 75 20 91 6 1,092 4%
Medium 265 695 180 791 794 412 142 421 1,931 5,631 22%
High 411 574 1,160 2,197 1,083 1,860 3,305 712 738 12,040 46% Source: (Environment Agency, 2010) Another important mitigation measure, is the Salmon and Freshwater Fisheries Act (1975), which requires that new obstructions in watercourses in the UK, or those rebuilt for more than half of their width, must include a fish pass. Fish passes are often the only means for fish to circumnavigate hydropower stations and so are key elements for the ecological improvement of running waters. The pass is generally considered effective if a significant proportion of individuals, relative to the population downstream of the obstacle, traverse this structure (Larinier and Marmulla, 2003). Although there is no official guidance on fish pass efficiency, it is considered that efficiencies should be 90 – 100% for adult salmonids ascending a river to spawn (Lucas and Baras, 2001; cited in Aarstrup et al, 2003). The success of fish passes is largely determined by whether the fish will find the passage and whether they will move through it. Aarestrup et al (2003) found that over 90% of tagged upstream Sea Trout (Salmo trutta morpha trutta) reached the nature-like bypass in Denmark subjected to study but only 55% of these traversed the pass, possibly because the pass was too short and the water flow insufficient. Experience has shown that efficiencies of 95 – 100% cent can be achieved on well-designed upstream fish passes with passage delays of a few hours to a few days (Chanseau and Larinier, 2001; cited in Larinier, 2008). The technology allowing for reasonably satisfactory downstream passage is now quite well-developed for juvenile salmonids and can be applied with some success; however, as regards other species, e.g. Eel, this technology is still inadequate (Larinier, 2008). Down-tream passes have been shown to only achieve 65-80% efficiency under optimal conditions. A search of the literature for a recent study for the European Commission (Mazza et al, 2011) could find no studies that evaluated the effectiveness of fish passes based on the long-term viability of fish populations traversing them. Larinier (2008) indicates that rigorous evaluation of fish passes is only rarely performed, except for Salmon and Shad. Fish passes are generally considered satisfactory by authorities based on direct observation of fish passage, compliance with design criteria and maintenance, rather than by thoroughly monitoring impacts on the affected population.
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In designing and installing fish passes in European rivers, it would seem that for such devices to contribute to biodiversity conservation, the unique aspect of each site and the needs of the species that use the section of river must be assessed on a case-by-case basis (Kroes et al, 2006; Thierrien and Bourgeois, 2000). The fish passes installed may need to be improved and adapted over time based on the results of monitoring efforts (Kroes et al, 2006). The potential impacts of low flows can be reduced by setting minimum acceptable flows, which can be calculated through the collection of historical flow data for a river (Young and Cane, 2004). Petts et al (1996) have suggested that a flow regime within a watercourse could contain four benchmark flows: Threshold Ecological Flow: to sustain biota, the exceptional minimum flow during rare drought events. Acceptable Ecological Flow: to sustain habitat for target species under low flow conditions, i.e. the normal summer low flow. Desirable Ecological Flow: to sustain connectivity throughout the length of the watercourse, i.e. the normal winter flow. Optimal Ecological Flow: maximises the area of utilisable habitat for the target species, which under natural conditions occurs infrequently. The AEF is considered to be the minimum acceptable level of flow and equates to the level of flow that is exceeded 95% of the time. Hydro schemes therefore design their weirs and intakes to prevent abstraction from the river when flows fall below this level. Pollution of the river, from silt etc., can occur during the construction of hydro schemes. It is therefore important to avoid significant long-term impacts by careful environmentally sensitive construction practices. In the UK, mitigation measures to mitigate hydro scheme construction impacts need to be included in an Environmental Management Plan, and these need to comply with SEPA and EA Pollution Prevention Guidelines40.
1.5.4 International biodiversity impacts and their mitigation
Potential impacts Energy from hydropower from other countries is not expected to be used in the UK in the near future. Possible future use of hydropower from Norway is discussed in section 1.17.
1.5.5 Conclusions
Summary of known impacts Large-scale hydropower schemes with impoundments generally result in substantial detrimental biodiversity impacts because they usually result in the loss (from flooding) of large areas of
40 Eg see http://www.sepa.org.uk/about_us/publications/guidance/ppgs.aspx
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habitat that are often of much higher biodiversity value than the deep open water reservoir habitat that replaces it. Impoundments schemes also normally result in profound changes in downstream flow regimes and therefore river habitats and associated species. Small-scale in river hydropower schemes, which is the type currently considered most feasible in the UK, have variable impacts on biodiversity. This is because they are usually sited on existing barriers such as weirs or waterfalls, which may already be a barrier to fish passage. Therefore, the siting of small-scale hydropower with fish passes may result in improved fish passage. Nonetheless, poorly designed hydro schemes pose a significant threat to fish populations and other aspects of riverine ecology where they can cause mortality of fish in turbines, restrict movement of migratory species and result in a reduction in river flow. It is important that hydropower schemes are appropriately located and avoid sensitive rivers and sites. Where they are operated, fish passes can effectively mitigate against the impacts of small- scale hydropower. Experience has shown that efficiencies of 95 – 100% can be achieved on recent well-designed upstream fish passes. However, it seems that installed fish passes could be better monitored which may reveal the need for improvements in some. Experience shows that even obstructions fitted with effective fish passage facilities cause a delay in migration of a few hours to a few days, and therefore successive hydropower installations have a cumulative impact on migratory populations. This may greatly constrain the number of small- scale hydropower stations that can be installed on rivers for where there is a policy to protect migratory species. Small-scale hydro schemes can also result in low river flows, but this can be avoided by identifying and supplying appropriate minimum flows in accordance with seasonal ecological needs. Knowledge gaps and required research Very few studies are available on the impacts of small-scale hydropower. In particular there are no studies that have evaluated the effectiveness of fish passes in terms of their ability to maintain the long-term viability of fish populations traversing them. Furthermore, although there are satisfactory mitigation options for downstream passage for several species, the current options are considered inadequate for some species such as Eels. The assessment of sensitivity of rivers where hydropower schemes could be installed in the UK is incomplete. For example, the sensitivity of 28% of rivers in England and Wales is unknown.
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Table 11: Summary of potential biodiversity impacts per unit of energy produced from the use of hydropower for UK energy requirements
Selected technology Small scale in-river Large-scale impoundment hydropower hydropower
Impacts in UK
Positive impacts Variable: Potential to Low: Some species can improve fish passage benefit from the creation / through modification of expansion of open water existing weirs and barriers habitats above with effective fish passes. impoundments, but these are normally mostly common and generalist species.
Direct mortality Low: Small number of fish Moderate: Sudden changes kill in poorly designed in river flows and levels may schemes. kill fish and other species
Direct habitat loss Very low from small-scale High: From large run-of river schemes: impoundment schemes, often affecting ecologically valuable habitats.
Indirect habitat degradation Variable: Small-scale hydro High: Large impoundment schemes can restrict schemes prevent upstream movement of migratory movements of migratory species and result in fish, and lead to major and reductions in river flows. sudden changes in river flow downstream, which disrupts in stream and bankside habitats.
Disturbance Low/Moderate during High during construction construction.
Secondary impacts No secondary impacts are Low/Moderate: Creation of likely from small-scale large reservoirs can result in schemes that utilise increases in tourism and existing weirs. recreation that have impacts on surrounding habitats, eg from increased
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trampling of vegetation, fires and disturbance.
Potential for mitigation Moderate: The most Low: Avoidance of habitats sensitive sites for in-river of high biodiversity value is schemes can be avoided critical but would be and well-designed fish difficult for new large-scale passes can reduce impacts schemes. Minimum flow considerably (as long as rates to maintain target there are not too many on a habitats and species can be watercourse). Minimum identified and set. flow rates to maintain target habitats and species can be identified and set. Careful construction methods are required to avoid pollution.
OVERALL RESIDUAL IMPACTS LOW HIGH
Potential for ecological Moderate: Measures can be Low: scale of habit loss compensation taken to enhance fish difficult to compensate for passage and flow rates over and impacts habitats are other stretches of the river. often difficult to restore
Impacts outside the UK None expected from abroad.
1.6 Onshore wind
1.6.1 Overview of the technology
Wind turbines transform the power from the wind to rotating mechanical power, which is in turn transformed into electrical power and then fed into the electricity supply systems. The turbines’ rated capacity can vary, up to 7.5 MW and as low as less than 100 kW for turbines mounted to roofs using micro-wind technology. The load factor (i.e. how much of the time each turbine is turning and producing electricity) averages around 30%, but varies from site to site. The connection of wind turbines to the supply system is possible to the low voltage, medium voltage, high voltage and extra high voltage systems41. There is usually a transformer directly beside each turbine, generating medium voltage electricity (usually around 30 kV) to avoid losses along low voltage cables. The medium voltage electrical current runs through buried cables from
41Deutsches Windenergie-Institut, 2001, Wind Turbine Grid Connection and Interaction http://ec.europa.eu/energy/technology/projects/doc/2001_fp5_brochure_energy_env.pdf
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several turbines in a wind farm to another transformer at a substation, where it is increased in voltage for connection to the high voltage transmission system. The substation includes a circuit breaker and an electricity meter for grid control. Construction of an onshore wind farm thus requires the installation of the transformer in the foundations of each turbine, a substation and access roads to each turbine. Size specifications of industrial wind turbines vary greatly with the rated capacity, with blades between 35 m (1 MW turbine) and 50 m (3 MW) long, sweeping areas between 3,904 m² and 7,854 m², at heights between 60 m and 105 m42. The turbine density should be less than 0.25 turbines per ha to allow sufficient distance between the blades (at least 4x rotor diameter, however more typically spacing is at least 10x rotor diameter). The base is from 10m2 for a 0.3 MW turbine up to 20 m2 for a 3 MW turbine. Concerns in relation to this technology include noise, visual impact on the landscape, wildlife and habitat impacts (in particular land disturbance during construction and bird collision during operation), radar interference and variability of the supply43.
1.6.2 Use in the UK
As the UK had the largest potential wind energy resource in Europe, the technology is well developed and its use is growing rapidly: it overtook hydroelectricity in 2007 as the UK’s largest renewable energy source44. As of March 2013 there were 4,491 installed onshore turbines with a total power generating capacity of 5,754 MW, generating approximately over 20 million MWh of electricity annually45. The majority of wind farms are located in Scotland, where they are widely distributed over most regions of Scotland (highlands, lowlands/borders and islands), although they are densest in the western central lowlands and Galloway, and almost absent from the central highlands area of the Grampian mountains46. In Wales they occur in south and south-west Wales, western-mid Wales and north Wales (outside Snowdonia National park) and north Anglesey. In England most occur at coastal sites especially in the south-west, but also upland areas such as the Central Pennines and some flat exposed lowlands, such as in the fenland areas of Cambridgeshire. Most UK commercial scale turbines are currently between 2 and 3 MW in size, and large-scale (5 MW and above) onshore wind farm arrays range from 2 to 150 turbines, with an average of
42www.aweo.org/windmodels.html gives detailed size specifications for a number of industrial models. 43 Sustainable Development Commission, 2005, ‘Wind power in the UK – A guide to the key issues surrounding onshore wind power development in the UK’ gives a comprehensive overview of the concerns. http://www.sd- commission.org.uk/data/files/publications/Wind_Energy-NovRev2005.pdf 44 Renewable UK, The voice of wind & marine energy, 2010, ‘Onshore wind’, http://www.bwea.com/onshore/index.html
45 http://www.renewableuk.com/en/renewable-energy/wind-energy/uk-wind-energy- database/index.cfm/map/1/status/operational/ accessed 27/3/2013
46 Scottish Natural Heritage 2012 Windfarm Footprint Map http://www.snh.gov.uk/planning-and- development/renewable-energy/research-data-and-trends/trendsandstats/windfarm-footprint-maps/
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around 15 turbines across the UK (14.5 in Scotland, 8.7 in England, 21.6 in Wales)47. Currently only five wind farms in Scotland and two in Wales have more than 50 turbines. The biggest and newest (Clyde, constructed in 2012) occupies around 4,700 ha with 152 turbines, i.e. 3.23 turbines per 100ha. The oldest, (Llandinam, Wales, constructed in 1992), has 103 turbines on 1,307 ha (i.e. 7.9 turbines per 100 ha), but is currently being renewed with dismantling of the existing turbines and erection of 39 more powerful turbines at a density of 3.0 turbines per 100 ha (CeltPower Ltd 2011). Turbine density may be higher in the lowlands. For example, Little Cheyne Court (Camber) wind farm on coastal grazing marsh has 26 turbines on 400 ha, i.e. 6.5 turbines per 100 ha48. In addition to existing wind farms, as of June 2012, 66 with a total capacity of 1,815 MW were under construction, 258 with 3,922 MW capacity were approved but not built, and 305 with 6,892 MW capacity were subject to planning applications (RenewableUK, 2012).
1.6.3 UK biodiversity impacts and their mitigation
Potential impacts Onshore wind is very likely to play an important role in meeting the UK and the EU’s renewable energy targets, thereby mitigating climate change and reducing its negative impacts on biodiversity. Nevertheless, inappropriate design and siting of wind farms has the potential to adversely impact on habitats and wildlife, particularly certain bird species. Furthermore, as wind farms require exposed areas with high winds, the sites of greatest wind potential tend to be coastal and upland areas, which are often of high biodiversity importance. The overall biodiversity impact of onshore wind therefore depends on appropriate location, design and monitoring of wind farm developments to minimise their direct and indirect impacts on biodiversity. There are four main ways in which wind farms can impact wildlife (EC, 2010a): direct habitat loss or degradation collision mortality disturbance and displacement barrier effect. Direct habitat loss is not usually considered to be a significant impact because the footprint of the turbines and associated infrastructure structure is normally relatively small (Langston and Pullan, 2003). However, although the footprint of a turbine is relatively small, typically around 0.25 ha (Dargie, 2004) wind farms also require access roads and other infrastructure. The total land take can be demonstrated by the example of the Llandinam wind farm repowering plan, which includes 42 3 MW wind turbines49, hardstanding area at each turbine base; 24.3 km on site access tracks and associated watercourse crossings; a 0.47 ha substation building and substation
47 http://en.wikipedia.org/wiki/Wind_power_in_the_United_Kingdom
48 http://en.wikipedia.org/wiki/Little_Cheyne_Court_Wind_Farm
49 of up to 122m tip height (i.e. height from ground level to the tip of the blade when vertical)
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compound; 2 meteorological masts; and on-site underground cabling (i.e. electrical infrastructure). In addition to the above components of the operational windfarm, the construction phase will involve construction compounds and laydown areas; temporary meteorological masts; and eight borrow pits (areas of stone excavation), on a site area of 1,307 ha (CeltPower Ltd 2011). Thus the total land take is approximately 30 ha, which amounts to 2.3% of the site, or 0.71 ha per turbine (0.24 ha per MW). From a study of Scottish windfarms, Dargie (2004) calculated that the average land take per turbine for their base, access roads, construction areas, borrow pits, and other infrastructure amounts to about 1.1 ha, of which 0.8 ha is normally restorable and 0.3 ha is permanent habitat loss. Thus, taking an average of these estimates of 0.5 ha per turbine, the current UK footprint from 4,491 turbines is approximately 2,245 ha, which is about 0.009% of the UK land area. Nevertheless, because the majority of onshore wind farm sites have to be located in upland and coastal areas, due to higher wind resource and isolation from human habitations (RenewableUK, 2011), they can have locally important impacts on habitats that support many species of conservation importance (Pearce-Higgins et al, 2009; cited in Pearce-Higgins et al, 2012). Wind farms are also often located on, or near, sensitive habitats (such as blanket bog, raised mires, wetlands or sand dunes). These can be significantly and permanently damaged over a much larger area than the construction and operational footprints, as a result of impacts on structure, ecological functioning and hydrology of sensitive habitats (EC, 2010a). For example, the Llandinam site includes valley mire, blanket bog, improved and semi-natural marshy grassland, and the revised plan relocates turbines and roads in an attempt to reduce their impact on these habitats. The vegetation on blanket bogs is particularly sensitive to lowering of the water table and activities that may result in erosion of the peat. Drainage around the turbine base and other infrastructure such as roads will change the current water flow patterns across and through the peatland (Dargie, 2004). Its impact is likely to be negative on intact bogs, but both negative and positive in degraded bogs, depending on the extent and nature of existing damage and mitigation and restoration measures (Stunell, 2010). A survey of existing wind farms on Spanish upland blanket bog found significant negative impacts on the integrity of the blanket bog plant community, with increased invasive species presence and more grassland (Fraga et al 2008). The construction of a wind farm on 400 ha of blanket peat in Scotland (with construction of 36 turbines and 20 km of dirt roads) caused marked increases in suspended sediment and dissolved organic carbon in the streams running off the site, as a result of erosion (Grieve & Gilvear 2008). A number of upland Scottish wind farms have been constructed on former grouse moors and/or rough sheep grazing. Others are on and around conifer plantations. For example, the Corriemoillie Wind Farm50 is being constructed on 350 ha of low quality commercial conifer forestry, which will be completely felled and the site restored to the previous open land vegetation. To reflect these potential impacts from windfarms, Scottish Natural Heritage have produced maps of Scotland dividing the land area into three zones of high, medium and low sensitivity of the natural heritage to onshore wind developments (SNH, 2009). The mapping is based on 1)
50 http://www.eon-uk.com/generation/2605.aspx
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habitats sensitive to disturbance and loss through construction, 2) potential impacts on birds (see below), and 3) potential impacts on landscape and recreation. The habitats identified as most sensitive are those with legislative protection and where either the habitat is so rare that any loss is regarded as serious; or where turbine installation or access tracks might interfere with the functioning of the habitat (e.g. peatlands which are dependent on their hydrology and coastal habitats like sand dunes and machair, which are prone to erosion). Thus Zone 3 includes all habitats protected at an international level and in addition peatland or coastal habitats protected at a national level. Zone 2 includes all other habitats protected at a national level and in addition non-designated areas containing good quality peatland and sand dune and machair habitats. Birds and bats are affected by mortality from collisions with turbines or associated structures such as electricity cables and meteorological masts. Bird collision rates vary greatly but typical averages range from 0.01 to 23 collisions per turbine per year (Drewitt and Langston, 2008), although these figures may be underestimates as they rely upon chance finding of corpses. Collision rates vary greatly between turbines depending on the design of the turbine, its location, species behaviour and the number of individuals that encounter it (Ferrer et al, 2012, Tucker et al, 2008). Certain bird species are more susceptible to wind turbine collision than others, particularly species that habitually fly at rotor height or larger less manoeuvrable species. There is evidence to suggest that populations of slow-breeding, long-lived birds such as raptors and vultures are particularly sensitive to collision mortality (EC,2010a, Martinez-Abrain et al 2012). Desholm (2009) developed a logical framework for ranking bird species with regard to their relative sensitivity to wind turbine-collisions, based on two indicators selected to characterise the sensitivity of individual species: 1) relative abundance; and, 2) demographic sensitivity (elasticity of population growth rate to changes in adult survival). This appears to be capable of identifying the species that are at high risk of being adversely affected by wind farms. The impact of wind turbines on overall bird species populations is relatively unknown. Desholm (2009) found that even where large numbers of passerines are impacted by collisions, they often represent insignificant segments of huge populations that, from a demographic point of view, are relatively insensitive to wind farm-related adult mortality. Pearce-Higgins et al (2012), in a study of the impact of onshore wind turbines on upland bird species, suggests that construction of windfarms can have a larger impact on bird populations than operation. From data on ten upland bird species, it was found that post-construction densities of Snipe (Gallinago gallinago) and Curlew (Numenius arquata) did not recover after declines as a result of construction work, with Curlew declining as much as 40%, although two species of passerines were found to increase during construction. Conversely, the study found little evidence of population impacts during the operational phase, suggesting that any increase in mortality through collision with turbines or other changes associated with wind farm operation has little impact on local populations. A map has been created indicating areas in Scotland where especially careful planning of wind farms will be necessary to avoid adverse impacts on vulnerable bird species (Bright et al 2008a). This map is based on the locations of statutorily protected Special Protection Areas, plus eighteen bird species of conservation priority. A high proportion of Scottish wind farms are on peatland (by stage in planning process: scoping 40%, application 38 %, approved 23%, installed 55%), although the area of peatland is only ca. 12% of Scotland (Bright et al 2008b). Peatland
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also contains a high proportion of sensitive areas for birds. Of the 1 km squares from the sensitivity map whose centres fall within peatland, 52% are high sensitivity, 32% medium sensitivity and 17% low/unknown sensitivity. This compares with figures of 37%, 31% and 32%, respectively, for Scotland overall. Another modelling approach indicated that current and proposed windfarm developments overlap significantly with Golden Plover (Pluvialis apricaria) populations in the Western Isles, the Western Central Belt and the Borders Hills, and was estimated at ca. 5% of the biogeographical population in each case (Pearce-Higgins et al 2008). Concern over the collision of bats has increased in recent years with studies estimating between 0 and 50 collisions per turbine annually (Birdlife International, 2011). In particular, locations close to roost sites or near hedgerows, woodland or rivers may be of greatest risk. A number of studies have shown a peak in mortality in late summer and autumn during dispersal and migration, and that migrating species may be particularly susceptible (EC, 2010a). Disturbance can lead to displacement and exclusion, and result in effective habitat loss. Certain species may be displaced from areas within and surrounding wind farms due to visual, noise and vibration impacts, particularly during construction, although operational impacts can also be significant. The creation of wind farm construction and maintenance roads may lead to some secondary impacts as a result of increased access, though few such roads are likely to allow unrestricted public access. Where increased and unregulated access does occur, biodiversity impacts may result from increased disturbance, accidental fires, fly-tipping and littering, hunting and other illegal activities. Disturbance effects appear to be highly species specific. In addition, the scale and degree of disturbance influences the significance of the impact, as does the availability and quality of other suitable habitats nearby that can accommodate displaced individuals (EC, 2010a). A “barrier effect” occurs where birds alter their local or migratory flight paths to avoid wind farms, which may result in additional energy expenditure or the disruption of linkages between feeding, roosting and breeding areas. Precise details of the impacts are difficult to study. Masden et al (2009), who examined the impact on 200,000+ migrating Common Eiders (Somateria mollissima ) passing over a significant wind farm development, found that the additional distance travelled as a consequence of the wind farm's presence was ca. 500 m and trivial compared with the total costs of a migration episode of 1,400 km. However, construction of further wind farms along the migration route could have cumulative effects on the population, especially when considered in combination with other human actions. Potential mitigation measures Evidence points to the critical importance of careful site selection in reducing the impact of wind farms on wildlife (Langston and Pullan, 2003). Impacts can be greatly reduced by avoiding high densities of wintering or migratory waterfowl or waders to minimise collision mortality, and all areas identified as important for birds (such as IBAs, SPAs, SACs, Ramsar Sites and SSSIs) should be avoided (Birdlife International, 2011). In particular, areas of high raptor concentrations, especially where the topography focuses flight activity, should not be used for the siting of wind farms due to the large detrimental impact that mortality of adult birds can have on raptor populations.
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There is evidence that turbine size and design can reduce fatalities per MW generated. Smallwood and Karas (2009) found that the installation of new generation (more powerful and efficient) turbines on an existing site (known as ‘repowering’) reduced mean annual fatalities by 54% for raptors and 65% for all birds per megawatt generated, as the new turbines generated almost 3 times the energy per megawatt of rated capacity compared to the old. However, the larger turbines appear to be an increased risk to nocturnally migrating bats that fly at a lower height than birds (EC, 2010a).
1.6.4 International biodiversity impacts and their mitigation
Potential impacts No importing of onshore wind power from outside the UK is expected and therefore these are not considered here.
1.6.5 Conclusions
Summary of known impacts Wind farms can impact biodiversity in four main ways: direct habitat loss or degradation, collision mortality, disturbance and displacement, and through barrier effects. However, most of these potential impacts can be avoided by avoiding sensitive sites and habitats. Consequently, many wind farms in the UK have no discernible impacts on biodiversity at all and, although few studies have examined their population impacts, it is unlikely that any species populations as a whole are significantly impacted by wind farms in the UK. Nevertheless, they can have numerous localised impacts on various sensitive habitats (e.g. blanket bogs) and species and particular care must be taken in the siting and design of such developments. Knowledge gaps and required research There remains a lack of information on the impact that windfarms exert on bird and bat populations as a whole. Even where large numbers of birds are impacted by collisions, they often represent insignificant segments of huge populations that, from a demographic point of view, are relatively insensitive to windfarm-related adult mortality.
Table 12: Summary of potential biodiversity impacts per unit of energy produced from the use of onshore wind for UK energy requirements
Selected technology Onshore wind
Impacts in UK
Positive impacts None identified.
Direct mortality Variable : Certain birds and bats are vulnerable to turbine collision mortality. Mortality rates are likely to be too low to lead to
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population level impacts on most species, but inappropriately sited wind farms could have substantial impacts on small vulnerable populations of slow-breeding, long-lived species.
Direct habitat loss Low: Direct land of turbines is very small, but impacts from associated service roads and other infrastructure can be more significant especially for habitats of high biodiversity importance.
Indirect habitat Moderate: Potential exists for significant damage of ecologically degradation sensitive sites, e.g. peatlands through hydrological disruption following construction of service roads.
Disturbance Moderate: Certain bird species may be displaced from areas surrounding wind farms due to visual, noise and vibration impacts, particularly during construction.
Secondary impacts Low: Increased disturbance due to littering, fires and hunting from increased access to remote areas created by construction and maintenance roads.
Potential for mitigation Moderate: Appropriate siting is crucial to avoiding sensitive habitats and reduce collision impacts to acceptable levels. Turbine layout and design can also reduce impacts
OVERALL RESIDUAL MODERATELY DETRIMENTAL IMPACT
Potential for ecological Moderate: Measures can be taken to offset small increases in compensation mortality, e.g. by reducing other mortality pressures or improving breeding productivity through habitat enhancement; habitat restoration or enhancement can offset habitat loses of some habitats.
Impacts outside the UK Low. See chapter on future energies.
1.7 Offshore wind
1.7.1 Overview of the technology
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Offshore wind technologies use the same principles as onshore wind: harnessing wind power to turn it into electricity. The difference is that the wind turbines are situated offshore (see Figure 13), which raises different environmental issues, ranging from the impacts of turbine installation to power transmission onto land.
Figure 13: An offshore windfarm in Lillgrund (Sweden) - Source: ©Ocean Power Magazine
Turbine foundations are solid structures that can be either fixed in the seabed or simply laid on it. Four types of structures exist (Figure 14): gravity based structures (GBS) have a large flat base that resists the overturning forces imposed by the turbine rotor. They are used in shallow waters (i.e. below about 5 m depth). monopoles are used in medium depth waters (between 5 m and 20 m), and are either drilled or driven into the sea bed (depending on the properties of the substrate). tripod structures are designed for use in deeper waters, and a prototype has been installed in Sweden. floating structures are being considered, but current cost disadvantages have impeded development so far.
Figure 14: Different types of foundations for offshore turbines (from left to right: GBS, monopole, tripod, floating structure) - Source: ©OWE, www.offshorewindenergy.org
Electricity is transmitted to the shore through medium voltage (around 33 kV) 3-core copper underground cables, which are buried through either excavation or drilling (depending on the
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properties of the seabed substrate). Onshore connection points (i.e. substations transforming the medium voltage current to a high voltage one) must be available for connection to the grid. In the near future, high voltage (220 kV) 3-core copper cables with a 1,000 mm² section, which limit losses over long distances, are likely to become more widespread. Transforming the medium voltage current from an array of offshore turbines into a 132-220 kV current will require offshore substations (see Figure 15).
Figure 15: The Wilney1 offshore substation for the Walney (UK) offshore windfarm. Source: ©Dong Energy
Concerns about the risks of ship collisions with offshore wind turbines have been raised. Although the probability of occurrence is low, collisions may result in severe environmental damage (for instance spills of toxic chemicals or oil). Offshore structures could also affect wildlife through noise emissions and vibrations during construction or operation, through electro- magnetic fields generated by the cables, or through the impact of their foundations on sea bed. The impacts of these factors on sea mammals, fish, seabed and sediment structures have not been thoroughly investigated.
1.7.2 Use in the UK
The UK has the largest wind power potential in the world, estimated at 400 TWh per year51, with significant potential for generation around Scotland and the East and West coasts of England thanks to relatively shallow waters and strong winds extending far into the North Sea. As summarized in Table 13, as March 2012, there were 568 installed offshore wind turbines (of which 536 are on monopoles) in UK waters, totalling 1,858 MW, and a further 665 turbines in construction, totalling 2,359 MW. The total number of operational and turbines in construction was 1,233. The average capacity of an offshore wind turbine is 3.27 MW. The trend is toward
51 Offshore Valuation Group, 201 – ‘ The Offshore Valuation’, pp34-35 http://offshorevaluation.org/downloads/offshore_valuation_exec.pdf
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turbines with a bigger installed capacity: the average capacity of turbines in construction is 3.54 MW52. In addition to the projects in operation or in planning, a further 40 GW of projects with leases and at various stages of pre-planning development, are being carried out. Recent projections have shown the total operating capacity will amount to 18 GW by 2020, supplying around 17% of UK electricity (offshore wind farms currently supply around 1.5% of electricity demand)53.
Table 13: Offshore windfarm projects in the UK (March 2012)
Operational wind Projects under Consented projects Projects in planning farms construction
Number Capacity Number Capacity Number Capacity Number Capacity (MW) (MW) (MW) (MW)
England 13 1,698 5 1,783 4 1,218 7 3,475
Northern 0 - 0 - 0 - 0 - Ireland
Scotland 1 10 - - 1 7 1 100
The development of offshore wind energy will require reinforcement of the onshore grid, with the construction of new substations for injection of offshore power. The provision of this infrastructure may decide the rate at which new wind farms can be connected. Currently, there are 400 kV substations in the North West at Deeside, Capenhurst, Frodsham, Stannah and Heysham; in the Greater Wash at Grimsby, Killingolme, Spalding, Walpole and Norwich; and many possible connections on the Thames estuary, both West and South of the proposed wind farms. The 132 kV system is weak in the North West, but offers many connection points on the Thames estuary and in the Greater Wash54.
1.7.3 UK environmental impacts
Potential impacts The impacts of offshore wind installations are frequently considered in the literature alongside those of wave and tidal energy devices under the category of Marine Renewable Energy Installations (MREIs), due to the similar environmental and ecological aspects of these developments (e.g. see Inger et al., 2009; Mueller and Wallace, 2008). The impacts of each technology are assessed according to six environmental aspects (after Inger et al., 2009): Habitat loss and degradation;
52 Renewable UK, ‘Ten facts about UK Offshore Wind’, http://www.bwea.com/offshore/ 53 Ibid
54 OWE 2010, http://www.offshorewindenergy.org/search_db_countries.php?grid_id=7
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Collision risk; Disturbance; Indirect effects; Artificial reef creation; and the Marine Protected Area effect (resulting from trawler exclusion). An alternative methodology applied by Wilhelmsson et al (2010) categorised the impacts temporally as follows: Short term impacts related to the initial installation of the turbines; Longer term and permanent impacts related to the on-going generation, transmission, and distribution of energy within the UK; Indirect impacts related to the expansion of the “super grid” and international energy distribution. Temporal considerations are considered under the aspects below. Habitat loss or degradation The construction of offshore windfarms can cause localised habitat loss and/or habitat change and risks damage to breeding and foraging areas (Keder and McIntyre Galt, 2009). Deployment of wind turbines and scour protection results in approximately 1-3% direct loss of seabed within the farm area, with each installation claiming up to 450 square metres (Willhelmsson et al, 2010). Other estimates are higher; Keder and McIntyre (2009) suggest it could be as high as 2-5%. Of all the MREIs it therefore has the greatest potential for habitat loss and/or displacement of marine organisms. Nevertheless, this impact is considered to be temporary (during construction/decommissioning) with potential long-term benefits as a result of artificial reef creation (Wilson and Elliott, 2009) (see below for discussion on the habitat creation potential). More moderate impacts are associated with potential changes to bird migration patterns, and changes to benthos habitats around turbines. However, given the diverse nature of local ecosystems it is difficult to provide general statements regarding the severity of other impacts. As with other MREI, avoiding the siting of offshore wind installations in ecologically sensitive areas will be an important consideration in limiting the negative impacts of habitat loss. Collision risk
In contrast to other MREI technologies, offshore shore turbines pose little or no submarine collision or entanglement risk due to the absence of moving parts under the water and the ease of navigation around surfaces (Wilson et al, 2007). The risk of seabirds and migratory birds that make sea crossings colliding with offshore wind turbines and the impact this has on their populations, is currently the topic of much debate (e.g. Desholm, 2009; Desholm and Kahlert, 2005; Masden et al, 2009; Petersen et al, 2011; Furness et al, 2013). Collision risks are expected to be highest for species that spend a lot of time flying, fly mostly at rotor height, have poor flight manoeuvrability and fly at night. Garthe and Hüppop (2004) and King et al (2009) took these factors into account, as well as each species conservation value and vulnerability to displacement, when they developed a single index of marine bird population vulnerability to
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offshore wind farms. Langston (2010) drew on a combination of experience from operational wind farms and the assessments by Garthe and Hüppop (2004) and King et al. (2009) to provide a three-level categorical assessment of a range of species’ sensitivity to collision risk, displacement, barrier and habitat/prey effects, and combined these together with a score for species conservation status to provide an overall wind farm risk. With respect to collisions risk alone two species were considered to be at high risk: Bewick’s/tundra Swan (Cygnus columbianus) and Whooper Swan (Cygnus cygnus). The following species were considered to have a moderate risk of collision: Bean Goose (Taiga) (Anser fabilis), Pink-footed Goose (Anser brachyrhynchus), Greater Whitefronted Goose (Greenland and European)(Anser albifrons), Greylag Goose (Anser anser), Barnacle Goose (Branta leucopsis), Brent Goose (Branta bernicla), Northern Gannet (Morus bassanus), Great Cormorant (Phalacrocorax carbo), Corncrake (Crex crex), Pomarine Skua (Stercorarius pomarinus), Long-tailed Skua (Stercorarius longicaudus), Arctic Skua (Stercorarius parasiticus), Great Skua (Catharacta skua), Mediterranean Gull (Larus melanocephalus), Lesser black-backed Gull (Larus fuscus), Herring Gull (Larus argentatus), Iceland Gull (Larus glaucoides), Glaucous Gull (Larus hyperboreus), Great black-backed Gull (Larus marinus), Black-legged Kittiwake (Rissa tridactyla), Sandwich Tern (Sterna sandvicensis), Common Tern (Sterna hirundo), Roseate Tern (Sterna dougallii) and Arctic Tern (Sterna paradisea).
Subsequently, the approach used by Garthe and Hüppop (2004) and King et al (2009) was further developed by Furness et al (2013), who assessed a range of species occurring in Scottish waters and incorporated new data from research on the flight behaviour of marine birds. They assessed collision risks avoidance/displacement risk separately because birds that are at most risk of collision differ from those at most risk from displacement. Their results are similar to those of Langston (2010) with the species most at risk of colliding with turbines being the larger gulls and skuas, as well as Northern Gannet (Morus bassanus) and White-tailed Eagle Haliaeetus albicilla). In contrast auks, shearwaters and Northern Fulmar (Fulmarus glacialis) were considered to have a very low risk of collisions as evidence indicates that they rarely fly at rotor height. Bird collision risks may be a higher for smaller scale generation schemes where the distance between turbines is small. There is also a possible “barrier effect” associated with smaller wind farms where the distance between turbines is shorter. As observed in relation to the Nysted offshore wind farm in Denmark, birds have been known to adjust their flight paths to avoid collision with turbines resulting in longer flight paths (Desholm, 2009). However, the total installed capacity for offshore wind farms is normally over 5 MW of installed capacity and the distance between turbines may create large enough corridors for birds to fly through. Both the location of the wind farm and the spatial distribution of turbines are therefore important factors in determining the overall impact on bird collisions (Keder & McIntyre Galt, 2009). Disturbance The greatest adverse impacts associated with the installation of offshore windfarms may result from noise from drilling required to erect turbines in the seabed. Noise in the marine environment has become an increasingly important emerging concern in recent years as a consequence of vessel activity and infrastructural developments (Bell and Side, 2011). Noise is created by drilling at broad bandwidths and thus has the potential to interfere with the inherent communication abilities of marine mammals. Harbour Porpoise (Phocoena phocoena) and Harbour Seals (Phoca vitulina) were found to demonstrate behavioural responses up to 20 km
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away. Damage to or loss of hearing is possible at source distances of 1.8 km for Harbour Porpoises and 0.4 km for Harbour Seals (Thomsen et al, 2006). Similarly, as fish use their otoliths or swim bladders to detect sound vibration and certain species rely on sound to communicate, hunt and forage, significant noise impacts associated with construction and decommission activities can interfere with hunting and breeding regimes (Gill, 2005). Assessment of the displacement impacts of offshore windfarms on seabirds is complicated by the extremely high variation in seabird count numbers, which inevitably results in low statistical power regarding the use of these data in impact assessment. Nevertheless, Petersen et al (2011) modelled the abundance patterns of overwintering Long-tailed Ducks (Clangula hyemalis) in relation to the Nysted offshore wind farm (Denmark) based on seven years of aerial survey data and concluded that the number of birds impacted by the development was trivial compared to the total flyway population, and therefore it is unlikely that the development will have any detectable influence on population. Furness et al (2013) concluded from a vulnerability assessment that divers and Common Scoters (Melanitta nigra) as most vulnerable to population- level impacts of displacement, but considered that these are likely to be less evident than impacts of collision mortality. Indirect impacts Similar to all forms of offshore energy generation, the installation of subsurface transmission cables has the potential to disrupt sedimentation with increased turbidity and sedimentation rates reducing the availability of light, thus impacting primary food production (Wilhelmsson et al, 2010). Increased sedimentation rates may also clog fish gills and obscure underwater visibility, thereby disrupting predator prey interactions (Balata et al, 2007). Transmission cables will need to be connected to the grid through substations; the construction of which could result in disruption to local ecosystems. The construction of overall energy infrastructure associated with power generation in a domestic electricity distribution context results in a number of indirect impacts onshore. Given the intermittency associated with wind, additional energy generated can be stored using “pumped storage” where energy is stored in large reservoirs. This electricity is produced again as part of standard hydroelectric generation. This indirect impact, and the disruption it causes to local ecosystems, should not be omitted from the overall biodiversity impacts of wind power. Artificial reef creation The increased hard substrate surface area provided by offshore developments in coastal environments has been shown to increase habitat for certain taxa and attract many marine organisms; and as a result the seabed around turbines often has a higher species diversity than surrounding areas (Willhelmsson et al, 2010). These artificial reefs can work to increase fisheries, rehabilitate habitat or attract ecotourists (Jensen, 2002). Wilson and Elliott (2009) show that that the net amount of habitat created by the most common design of offshore wind turbine, the monopile, is up to 2.5 times the amount of area lost through the placement, thus providing a net gain even though the gained habitat may be of a different character to that lost. Optimum reef conditions can be created through consideration of a number of key factors including: geographical location, size, orientation, complexity, durability, type of material, surrounding substratum, proximity to natural habitats, depth and water conditions (Perkol-Finkel
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and Benayahu, 2005). It is unlikely that renewable energy infrastructure will satisfy the full range of requirements for a truly successful reef resulting in full colonisation and succession sequences, habitats / stocks / communities. However, careful planning at the early stages of development, allows the development of offshore wind energy to satisfy a number of these requirements, and thereby become at least partially successful at creating habitat around its tower and foundation (Wilson & Elliott, 2009). Marine Protected Area effect Trawling exclusion from offshore wind farms is expected to reduce physical disturbance of benthic communities and create more favourable environments for long-lived species (Jennings and Kaiser, 1998; Tillin et al, 2006). This is particularly the case for large wind farms where access is restricted over a large area that can resemble a ‘no-take zone’. The impact of this will depend on location, as it is possible that the location of wind farms may be particularly valuable in terms of conservation, restoration or fisheries management. Wilhelmsson et al (2010) consider there to be likely local long-term benefits on the benthic environment and fish populations, and a possible broader benefit for marine mammals. Potential mitigation measures Some of the mitigation measures proposed for offshore wind will apply to all other types of offshore energy. This is particularly true for higher level policy measures. Indeed, offshore wind impacts may be minimized if an attempt is made to share infrastructure related to the transmission and distribution of energy (Wilhelmsson et al, 2010). There is a potential to increase the capacity of windfarms to act as artificial reefs. A key aspect in ensuring this happens is to ensure a wider appreciation of this requirement amongst the industry, regulators and marine stakeholders. Greater emphasis is needed of survey and research requirements on the broader range of conservation, commercial or recreational gains which could be achieved (Wilson & Elliott, 2009). While certain recommendations can be made with respect to design and project implementation, the nature of more in situ mitigation measures will be site specific and will need to consider the unique characteristics of the relevant local ecosystems (Keder & McIntyre Galt, 2009). In general, adequate spatial distribution of turbines will help minimise the impacts associated with avian collision and farms should be located in a position that is perpendicular to standard flight paths. A review of other potential technologies and techniques for reducing bird collisions found that the most effective measures are likely to be temporary shut downs during high risk periods and remote population monitoring, eg by radar (Cook et al, 2011). Options for the mitigation of noise impacts includes bubble curtains, scaring devices, and seasonal and spatial planning, although these have varying degrees of efficiency (Koschinski, 2011). Alternatively, as has been the case predominately to date, marine mammal observers can be used to detect the presence of marine mammals, which may result in the activities being delayed or, where practical, gradually ramped up (Bell and Side, 2011).
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1.7.4 International environmental impacts
Given its large potential renewable offshore energy capacity, the UK has the potential to become a net exporter of energy. Scotland alone possesses up to a quarter of Europe’s offshore wind and tidal energy resources (The Offshore Valuation Group, 2010). In order for this to happen, the UK will need to upgrade both its domestic energy distribution, while looking for more opportunities to connect to a European grid. A transnational European electricity grid is crucial for the long term potential of renewable energy in the United Kingdom (UK). In 2010, the European Commission proposed a network of energy super highways across the EU as part of an “energy blueprint” (COM (2010) 677 final). The expanded grid would carry renewable energy from the periphery of the Union to major consumption areas in central Europe. The system would also offer further connection opportunities for offshore renewable energy technologies (Fichaux and Wilkes, 2009). In an electricity supply system with high renewable generation, an expanded grid offers many benefits. A large diversity of renewable generation across the EU would increase security of energy supply, helping to compensate for periods of below average generation in some areas. The next EU budget (the Multiannual Financial Framework for 2014-2020) proposes the allocation of EUR 200 billion worth of funding for the implementation of grids for electricity, oil and gas, as part of the “Connecting Europe Facility” (COM (2011) 17 final). Nevertheless, the installation of a supergrid will have a number of environmental costs associated with the manufacture, installation, maintenance and dismantling phases. A life cycle assessment of 450 kV HVDC power transmission cable by Birkeland (2011) found that the impacts per MW/km of cable are: increased marine eco-toxicity (14.2kg 1,4 –DCB –eq/MW/km), human
toxicity (1200kg 1,4-DCB –eq/MW/km) and greenhouse gas emissions (214 kg CO2 –eq/MW/km). In addition, the manufacturing of cables will require large amounts of metals and plastics, which are energy intensive and lead to resource depletion along with environmental impacts associated with extraction processes. Installation, maintenance and dismantling will require the use fossil fuels and oil for lubrication in marine vessels and equipment, which will result in marine eco- toxicity and eutrophication. The impacts related to the expansion of the offshore supergrid will be similar for all forms of offshore power generation including tidal range, tidal stream and wave energy. The information from this section has not therefore been repeated in subsequent sections.
1.7.5 Conclusions
Offshore wind farms have the potential for a number of important positive and negative impacts over different temporal scales (Table 14). Significant short-term impacts are expected both through habitat loss (from 1-5 % of the total area) and the noise impacts of pile-driving during construction, which may particularly affect marine mammals (see impacts from oil production above). Collision risks for many seabirds and migratory birds are uncertain and will vary amongst species; with those that spend a high proportion of time flying at rotor height, have poor manoeuvrability in flight and fly at night being at most risk. In general, it seems unlikely that detectable population impacts will occur on dispersed seabirds and broad-front migrants from collisions with offshore wind turbines according to expected levels of deployment. However,
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substantial impacts could occur from inappropriately located large-scale wind farms on seabirds when they are localised (eg if close to breeding colonies) and on migrants that use specific narrow flight paths. Offshore wind farms may have some significant benefits, including their potential to provide artificial reefs. The monopile alone may create up to 2.5 times the amount of area lost through their placement, but of other habitats than those lost. But probably more importantly, fishing by trawlers will not occur within wind farms. This will affectively create no-take zones for fish and also allow recovery of trawled benthic habitats and their associated species. This may lead to substantial biodiversity benefits, although they will depend, to some extent, on the location of the farm and the level of previous fishing use. As with other MREI, there are likely to be impacts associated with the creation of offshore grids, including some habitat loss and degradation. Table 14 Summary of potential biodiversity impacts per unit of energy produced from the use of offshore wind for UK energy requirements
Selected Offshore wind technology
Impacts in UK
Positive impacts Uncertain: Artificial reef impacts may potentially compensate for some habitat lost, (more habitat, but of a different kind). Trawling exclusion benefits expected.
Direct mortality Variable: Likely to be low for most dispersed seabirds and migratory species, but potentially high impacts on localised seabirds and some migrants from inappropriately placed large-scale windfarms.
Direct habitat loss Low/Moderate: 1-5% for the entire development area including initial construction and transmission.
Indirect habitat Low/Moderate: Construction of turbines and installation of subsurface degradation transmission cables is likely to disrupt local ecosystems, e.g. from higher turbidity causing reduced visibility and light penetration, affecting primarily productivity and habitat suitability from some fish and invertebrates
Disturbance Low/Moderate: Noise from pile driving likely to cause disturbance to marine mammals, but impacts will probably be temporary
Secondary impacts Uncertain: Growing use of wind power could escalate need for more pumped storage of hydroelectric installations given wind intermittency.
Potential for Moderate: Appropriate location is of key importance, but turbine mitigation orientation and spacing and other measures can reduce collisions; and
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Selected Offshore wind technology
sensitive construction methods and timing can reduce other impacts
OVERALL MODERATE MIXED RESIDUAL IMPACTS
Potential for Uncertain: The creation of habitat on the turbine piles and exclusion of ecological bottom trawlers may compensate for impacts to some extent, depending compensation on the impacted habitat type and its condition. If not, then protection, restoration / enhancement of other areas of similar habitat might also be possible
Knowledge gaps and required research The noise impacts of offshore wind farms on marine mammals are poorly understood (Madsen et al. 2006), with most available studies being focused on just two relatively common species, namely, harbour porpoise (Phocoena phocoena) and harbour seals (Phoca vitulina). According to Dolman et al. (2007), no such field studies have been conducted for any species of cetacean other than harbour porpoise. In addition, there is a lack of understanding of the chronic long-term impacts of operational noise on marine wildlife. Further study is required on the impacts of artificial reef creation on the benthic environment. It is not known what the impact of trawler exclusion will be in areas of low importance to fish. Finally, the collision risk for birds is uncertain and therefore more research is required on actual collision rates and the factors affecting them.
1.8 Microgeneration of electricity
1.8.1 Overview of the technology
Microgeneration (or micropower) refers to small-scale energy production for individual buildings or communities, from technologies such as: Solar photovoltaics (PV) Micro-wind turbines mounted on building roofs or on masts Micro-hydro turbines producing electricity from naturally flowing water Micro-Combined Heat and Power (CHP) providing both heat and electricity
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Ground source heat pump Anaerobic digestion (see impacts in waste section, as rarely used for microgeneration) Rather than a technology, microgeneration is the term used to refer to a decentralized power generation strategy, based on distributed low carbon energy sources harnessed at a small scale (usually less than 5 MW) and owned by residents of a building or by communities. Locally owned electricity is generated rather than drawn from the National grid, and can be used on-site or injected to the grid, provided an export meter is installed: it is then sold at feed-in tariffs (FIT) fixed as incentives by the DECC in the FIT scheme: under this scheme, installations receive an attractive 'cash back' payment for every kWh of electricity generated. The tariff levels depend on the type of technology and the size of the system. If the equipment is not connected to the grid, surplus electricity can be stored in a battery.
Solar Photovoltaics (PV) This technology uses solar panels on rooftops to harness the sun’s energy and produce electricity to run appliances (see Figure 16). Each solar panel is composed of cells made of one or two layers of semi-conducting materials such as silicon. Figure 16: Microgeneration by solar PV
Source: MSC Micro-wind turbines Mounted on roofs or on masts, wind turbines can be part of a microgeneration system, as shown in Figure 17.
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Figure 17: Microgeneration by wind turbine
Source: MSC Micro-hydro Hydro electricity is produced from fast running streams or rivers. The hydro system converts the energy in the flowing water to electrical energy, as shown in Figure 18. It relies heavily on the volume of water and will produce more energy in winter when there is more rain. Figure 18: Microgeneration by hydro
Source: MSC Hydro power usually involves building on a stream bank and extracting and diverting a part of the flow (through pipes or by-pass channels) for several hundred meters, from the river to an inlet on an existing weir to pass through the turbine. Special care must be taken not to damage local fish stocks. Micro-CHP Combined heat and Power (CHP) generation uses a classic gas-fuelled engine to generate electricity in addition to heat (Figure 19), by piping the steam from the boiler to a turbine. The
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electricity produced is six times less abundant than the heat produced55, but requires no extra fuel resource. Figure 19: Microgeneration by CHP
Source: ENMAX Anaerobic digestion (AD) Using anaerobic digestion to produce energy consists in having biodegradable materials (e.g. sewage works, energy crops, food waste, abattoir waste, etc.) broken down by microorganisms in the absence of oxygen. The micro-organisms then produce a biogas that can be used as a fuel in a gas engine. Such processes do produce greenhouse gases, but the carbon released originates from biodegradable materials grown in the recent past. If the materials are regrown, they will take that carbon out of the atmosphere once again and the process will have been carbon neutral, as opposed to emissions from burnt fossil fuels, which have sequestered carbon for millions of years and which increase the overall levels of carbon in the atmosphere. Ground source heat pumps Ground source heat pumps circulate a mixture of water and antifreeze in a loop of pipe buried in the ground, at a depth where it is remains at a constant temperature (around 15°C all year long). When the liquid is pumped around the loop, thermal heat from the ground is absorbed and transferred to radiators, underfloor heating systems or water heating equipment.
55 http://www.energysavingtrust.org.uk/Generate-your-own-energy/Micro-CHP-micro-combined-heat-and-power
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Figure 20: Microgeneration by ground source heat pump
Source: MSC The loop of plastic pipes can be laid flat or coiled in trenches about 1.5 to 2m below the surface, and in some instances can be buried vertically into the ground, after drilling a vertical borehole.
1.8.2 Use in the UK
Total microgeneration in the UK currently amounts to 170.963 MW, distributed between solar PV (120.16 MW), micro-wind (22.9 MW), hydro (12.75 MW), ground source heat pumps (10MW), anaerobic digestion (5 MW) and micro-CHP (158 kW). Although no specific target has been set for microgeneration of electricity, a microgeneration strategy was proposed in June 2011 after a strategy consultation.56 This strategy involves financial support through advantageous feed-in tariffs (to be reduced as the sector achieves critical mass and innovation drives down costs) and a commitment to ”identify [the nonfinancial barriers] and find ways to addressing them”. It is expected that, by 2020, the scheme will support over 750,000 small-scale, low carbon electricity installations.
1.8.3 UK biodiversity impacts and their mitigation
Potential impacts The environmental impacts of microgeneration are predominately positive, via a decrease in the carbon emissions of households and in potentially stimulating a behavioural change towards low carbon economy. The recent review by Birdlife International (2011) expects ‘minimal’ conservation risks from its use and microgeneration features strongly in its recommendations. In
56 DECC, 2011, ‘Microgeneration Strategy’, page 4 http://www.decc.gov.uk/assets/decc/11/meeting-energy- demand/microgeneration/2015-microgeneration-strategy.pdf
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addition, as it is associated with human habitation, frequently in urban settings, the potential for conflict with wildlife is minimised. Despite this, it is acknowledged that microgeneration may have localised ecological impacts on biodiversity that need to be considered. As microgeneration refers to a range of different energy technologies, categorised by similarities of scale rather than functionality, the possible impacts are considered separately. In the case of small scale installations of solar photovoltaics (PV), it is possible that the installation of solar panels may have impacts on bats by blocking access to roosts or causing disruption to nesting birds (Scottish Natural Heritage, 2009b). Bats are particularly sensitive to disturbance at roosting sites (Jones and Cooper-Bohannon, 2009) and therefore potential for disturbance/displacement exists during installation. The installation and operation of small-scale wind turbines is likely to have impacts on bats and birds in the UK, which incorporates a number of European protected species. Bat mortality resulting from actual or near-collision with operational wind turbine rotors is a widespread phenomenon that is not well understood. Research shows that one of the potential causes of bat mortality might be linked to the feeding on insects which might be attracted to wind turbines due to their colour characteristics (Long et al, 2011). Although this has been investigated in the context of large wind farms, similar effects are likely to apply at the micro-scale. Moreover, as bats rely on information contained in high-frequency echoes to determine the nature and movement of a target, it has been found that echoes from moving turbine blades render sound which might be attractive to bats or which might be difficult for them to detect in sufficient time to avoid collision (Long et al, 2010). Wind turbines situated close to roost entrances might also cause a particular obstruction. Research projects at the University of Stirling to further investigate the impacts of micro-wind turbines on wildlife are currently underway.57 Furthermore, a three year project to estimate the impact of wind turbines on bat population in Britain is also currently being carried out (Jones and Cooper-Bohannon, 2009). There are thought to be minimal ecological impacts of small scale hydro power generators, although environmental considerations need to be taken into account in due planning and installation process (Scottish Natural Heritage, 2009a). In particular, the micro-hydro generators need to minimise the impacts on river ecosystems and fisheries (see mitigation below). Poorly designed and poorly operated hydropower schemes can have harmful effects on fish stocks, for example where fish are killed by turbines or where the schemes have an effect on fish migratory paths (SPLASH, 2006). Potential mitigation measures In general, a careful setting of microgeneration is likely to mitigate against potential impacts. With regard to siting of wind turbines, consideration of the location of birds’ nests and bats’ roosts, their feeding grounds and other factors relating to their incidence needs to be undertaken. There are also other different factors in play, which might influence the probability of bats mortality. In particular, as mentioned above, it has been found that the choice of colour of the wind turbines might represent a potential mitigation measure. Long et al. (2011) found that
57 E.g. http://www.sbes.stir.ac.uk/people/postgrads/tatchley/index.html
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commonly used ‘pure white’ and ‘light grey’ colour were likely to attract significantly more insects than other colours tested, suggesting that the choice of different colours might decrease the attraction of the insects and hence might help to contribute to decrease in bats mortality incidence. Various technological advancements might help to mitigate the potentially harmful impacts of micro-hydrological power generators. These include particularly turbine designs – e.g. oil-free turbines, which avoid leakage of oil to ecosystems; or fish friendly turbines, which decrease or avoid damage to fish by, for instance, reducing the number of turbine blades or other design improvements.
1.8.4 International biodiversity impacts and their mitigation
Potential impacts On the international scale, the environmental impact of microgeneration is mainly related to the production process and life-cycle impacts of the technologies involved.
1.8.5 Conclusions
Summary of known impacts Although the environmental impacts of some of these power sources are not well understood, it is unlikely that they will result in significant biodiversity impacts, largely due to their small footprints. The greatest potential for negative impacts arise from the use of micro-wind generation through collision mortality of bats and birds. Micro-hydro may also result in direct mortality of fish on turbines (see above). However, these impacts are expected to be minimal and easily mitigated via careful siting away from sensitive areas and the installation of fish friendly turbines. Knowledge gaps and required research Although some research projects are currently underway to address the environmental impacts of microgeneration, significant knowledge gaps remain. These particularly include the impacts of micro-wind turbines and micro-hydro on habitats and species. Also, there is a need to investigate the implications of a large-scale deployment of these technologies in order to estimate their long term implications for environment and biodiversity.
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Table 15: Summary of potential biodiversity impacts per unit of energy produced from microgeneration of energy in the UK
Selected technology Microgeneration
Impacts in UK
Positive impacts None (besides a decrease in GHG emissions)
Direct mortality Low/Moderate: Possibility of limited mortality of bats/birds in micro-wind installations, and fish mortality in micro- hydropower.
Direct habitat loss Low: Possible loss of bat roosts in PV installations.
Indirect habitat degradation None
Disturbance Low: Possible disturbance to roosting bats and nesting birds in houses during installation of PV.
Secondary impacts None
Potential for mitigation High: Potential via careful siting of microgeneration
OVERALL RESIDUAL IMPACTS LOW
Potential for ecological Low compensation
Impacts outside the UK Limited impacts from the extraction of raw materials and production of microgeneration equipment abroad.
1.9 Crop-derived biofuels
1.9.1 Overview of the technology
The crop-derived biofuel category in this study refers to those crops currently used in large-scale commercial production of biofuels. They are used to produce two main types of liquid biofuel: biodiesel (from oilseed rape, sunflower, soya bean, jatropha, palm oil) and bioethanol (from wheat, sugar beet, sugar cane, maize). All of these are also used as food for animal or human consumption, with the exception of jatropha. In addition, the variety of wheat used for distilling to bioethanol is not the same as that
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used for human consumption. Biofuels can also be derived from used cooking oil and tallow; however, for the purposes of this report, these are considered under Genuinely Residual Wastes as their provenance and environmental impacts are more closely related to that category. The term ‘biofuel’ is most frequently used with respect to these fuels’ use in transport. The process of producing biodiesel involves the crushing of oilseeds, which yields vegetable oils that are transformed into biodiesel through trans-esterification. Bioethanol is produced by fermenting the sugar components derived from sugar and starchy crops. As these methods were the first to reach large-scale commercial viability and thus widespread use, these fuels are commonly referred to as ‘first generation’ biofuels. This is used to distinguish them from more advanced production processes such as those used to derive biofuels from ligno-cellulosic feedstocks (‘second generation’) or from algae (‘third generation’).
1.9.2 Use in the UK
Under the EU Renewable Energy Directive (RED) of April 2009, all Member States are required to source 10 per cent of their transport fuels from renewable energy by 2020. In the UK, this Directive was preceded, in April 2008, by the Renewable Transport Fuel Obligation (RTFO), which is one of the main mechanisms established by the national government for reducing carbon emissions from transport. The RTFO sets a requirement on all transport fuel suppliers to ensure that 5 per cent of all road vehicle fuel was supplied from renewable sources by 2010, with the aim of reducing carbon dioxide emissions of between 2.6 – 3 million tonnes per annum by the same year (RFA, 2011). Furthermore, the RTFO requires suppliers to report on net greenhouse gas savings and the sustainability of the fuels they supply. According to data from the UK Department for Transport (DfT, 2011), 1.52 billion litres of biofuel were supplied in the UK over the 2010/11 obligation period, of which 899 million litres was biodiesel and 618 million litres was bioethanol. A further 0.4 million litres of biogas was reported. The most widely reported feedstock of biofuels in the UK over the 2010/11 obligation period was used cooking oil (30 per cent), followed by soy (15 per cent), maize (14 per cent) and wheat (10 per cent). Excluding used cooking oil and tallow, which are considered as residual wastes, the main feedstocks for biofuels grown in the UK in 2010/2011 are shown in Table 16. Figures of the area of key bioenergy crops from UK in 2007 are shown in Table 17. Table 16: UK biofuel volumes per feedstock from the UK (DfT 2011)
Feedstock Volume of biofuel (million litres) 2010/2011
Wheat 119.9
Sugar beet 68.5
Oilseed rape 9.4
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In 2010, approximately 97,000 ha of arable land was grown for biofuel feedstocks, on around 1.7% of arable agricultural land in the UK (Defra, 2013). Table 17: UK land areas used for agriculture and crops for biofuels
2008 2009 2010 2011
Total Utilised 17 703 17 325 17 234 17 173 Agricultural Area (UAA)a, in thousand hectares
UUA as a proportion of 73% 71% 71% 70% total UK area
Total Arable Areab 5 900 5 922 5 847 5 932
Wheat 2 080 1 775 1 939 1 969
- of which used for 0 0 75 Not yet bioethanol available
Oilseed Rape 598 570 642 705
- of which used for 15 18 8 Not yet biodiesel available
Sugar Beet 120 114 118 113
- of which used for 7 9 14 Not yet bioethanol available
UK area used for 22 27 97 - biofuel crops
% of UK arable area 0.4% 0.5% 1.7% Not yet usd for bioenergy available a Includes all arable and horticultural crops, uncropped arable land, common rough grazing, temporary and permanent grassland and land used for outdoor pigs (excludes woodland and other land). b Arable area is defined as the area of arable crops, uncropped arable land and temporary Source: Defra (2013) Experimental Statistics. Area of Crops Grown For Bioenergy in England and the UK: 2008-2011 The figures from DfT show a large proportion (30 per cent) of biodiesel derived from used cooking oil, primarily from the Netherlands, the UK and Germany. This may be partly explained
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by the 20p duty differential, which was removed from other sources of biodiesel and bioethanol in 2010.58 Due to the expiration of this duty differential in April 2012, it is reasonable to expect that supply of used cooking oil will reduce in the future, with a corresponding increase in other feedstocks. As there are no known negative impacts of used cooking oil as a feedstock, the replacement of used cooking oil by other feedstocks could have an adverse impact on biodiversity. Table 18: UK biofuel volumes per feedstock imported
Country Imported Volume of biofuel Feedstock (million litres)
Argentina Soy 196.3
USA Corn 156.4
Brazil Sugar cane 124.0
Relatively small amounts of palm oil (3.5 per cent of the total crop feedstocks) are used as a biodiesel feedstock in the UK currently. In 2010/11, 36.2 million litres were consumed from Indonesia (21.2 mL), Malaysia (12.7 mL) and India (2.3 mL) (DfT, 2011).
1.9.3 UK biodiversity impacts and their mitigation
Potential impacts The environmental issues of growing biofuels reflect those related to arable agricultural production. Globally, the conversion of natural or semi-natural land to agricultural land (direct land-use change) remains one of the most significant pressures on biodiversity worldwide and is increasing (FAO, 2008). Biofuels also result in the same issues related to the production of arable crops such as loss of soil fertility, reduced biodiversity value, agricultural run-off, pollution of watercourses, fragmentation of habitats, etc. These impacts depend on the crop cultivated, the location, and the management practices applied. Additionally, there are indirect land use change (iLUC) impacts resulting from the displacement of previous land uses to other areas, some of which may not have previously been in production, i.e. ‘conversion’ iLUC. An increase in biofuel production can also result in ‘intensification’ iLUC, in which agricultural areas remaining in production are intensified in order to maintain the overall output without expanding into new areas (Bertzky et al, 2011). The investment in first generation and second generation biofuel consumption will result in different implications for biodiversity. In essence, the biodiversity impacts of the production of biofuels can be seen as a product of: the biodiversity present prior to land conversion;
58 http://www.hmrc.gov.uk/briefs/excise-duty/brief1810.htm
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the biodiversity present after land has been converted (or the on- farm impacts); the off-farm impacts on the surrounding areas (such as nutrient run- off); and indirect land use change as a result of increased demand for agricultural land (after Campbell and Doswald, 2009). Specific management practices are also an important contributing factor to the biodiversity output. Direct land use change The main impact from agriculture is pressure to convert natural lands to agricultural lands, which generally support less biodiversity. Some positive impacts may however occur when badly degraded lands are converted to agricultural areas, as vegetation will reduce pollution leaching, improve soil and water retention which may benefit wetland habitats. The European Commission has calculated that 17.5 million hectares of land within the EU are likely to be required to meet the 10 per cent biofuels target by 2020,59 amounting to about 10 per cent of the total Utilised Agricultural Area (UAA) in the EU27 (EC, 2008; cited in Elbersen et al, 2012). Half of this production was expected to be derived from the cultivation of rotational crop derived biofuels, with the remaining 50 per cent to be derived from ligno-cellulosic and perennial biomass crops60 or from imports from outside the EU. Assuming 50 per cent of UAA land in the UK is also used for crop-derived biofuels and the remainder for dedicated energy crops, this would represent approximately 0.8 million hectares for first generation biofuel production by 2020. The Alpha Pathway under the DECC 2050 Pathways Analysis report (DECC, 2010, DECC, 2010a) envisages a scenario of 10 per cent of total UK land used for energy crops, which represents a larger area dedicated to growing biofuel feedstock. This extra land could come from the conversion of semi-natural areas, agricultural land already in production (through displacing existing forms of production), or through the utilisation of marginal or degraded land. In the UK, it is expected that most, if not all, bioenergy crops for biofuels will be grown on existing productive agricultural land. This is due to the considerably lower yields of these crops on marginal or degraded lands, and consequently a reduced incentive for investment. Relatively strong protection of natural and semi-natural lands is expected to ensure no direct conversion of these areas to biofuel production (CCC, 2011). The direct impacts of biofuel production will depend on previous land-use and the biodiversity present after conversion. Although some species may benefit, consireable net losses in biodiversity may be expected if it results in land use change from pasture (especially extensive systems), but also forests, wetlands or peatlands to arable land.
59 Note, however, that the OECD (2006) is less optimistic and estimates that about 45 million hectares of land are required to reach the EC-targets by 2020. Their estimates are purely based on 1st generation biofuel technologies and they assume yields to remain at the same levels as they are now (Elbersen et al, 2012).
60 Under the assumption that second generation biofuel technologies would be commercially available before 2020.
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Few spatially-explicit models exist that identify where changes will occur. Hellmann and Verburg (2008) do this at European scale, but no similar studies were found specifically for the UK. The extent and impacts of direct land use change will depend to a degree on the crops selected for two reasons: Some have significantly higher returns per hectare and have a more efficient transformation rate (biomass to energy yield), therefore requiring less land per unit of energy supplied. Feedstock require different management practices which will result in varying environmental impacts. In Europe, biofuels are predicted to encroach into semi-natural steppes and long-fallow dry cereal systems, which are amongst Europe’s most biodiverse habitats (reported in Campbell and Doswald, 2009). The same review reports that negative impacts across all taxa are expected from biofuel expansion in Europe. Impacts from agricultural practices Agriculture has environmental impacts that depend on the management practices chosen. These impacts result in pollution from fertilisers, pesticides, soil erosion, water loss, expansion of invasive species, etc. These impact in turn on biodiversity. In the EU, the most important domestic sources of biofuels are wheat, sugar beet and rapeseed oil (Elbersen et al, 2012). Wheat in the EU is often grown as a monoculture or in rotation with other cereals. Polycultures and crop rotations are shown to have less negative environmental impacts (BIO, 2010) than monocultures or rotations of the same types of crops. Row crops61 such as sunflowers or sugar beet tend to have a higher proportion of exposed soil due to the linear planting and relatively slow growth of crops, as a consequence impacts such as soil erosion tend to be higher on arable land with row crops (Nowicki et al., 2009). The use of pesticides and fertilizers and the irrigation needs of crops risk water and soil pollution, as well as negatively impacting aquatic ecosystems downstream of the cultivated areas. A study by Börjesson and Tufvesson (2011) investigated the resource efficiency and environmental performance of crop-based biofuels in Northern Europe. It showed that different crops have different impacts. For example, eutrophication is reported to be two to three times lower from biofuels based on sugar beet, ley and willow, compared to biofuels based on wheat, when unfertilized grassland is used as a reference. Second generation biofuels are expected to have less negative impacts than first generation biofuels. A study by Rowe, Street and Taylor (2007) discuss the impacts of these crops in the UK. Second generation biofuels include SRC willow and poplar, miscanthus and waste (see also the sections on biomass and genuinely residual wastes). Impacts on landscapes are expected to be higher from these crops than first generation biofuels, as they are less common in current landscapes and would be higher (5-6 m for SRC for instance). Despite some mixed results, the general consensus is for an increase in carbon sequestration from arable land to SRC or
61 Crops planted in specific rows as opposed to semi scattered seed.
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Miscanthus (until a balance is achieved); as well as a reduction in nitrogen leaching and reduced erosion rate compared to arable land, and possibly co-benefits by phytoremediation. All these will have beneficial indirect impacts on biodiversity. The review of biodiversity impacts also show that SRC can have increased farmland flora diversity compared with arable crops, increased avian density and richness compared to both arable and improved grassland, large numbers of insect species, and more (but common) butterfly species. Miscanthus is reported to have been less studied, but irrigation may be an issue. Indirect land use change (iLUC) The increasing demand for biofuels produced agricultural land is believed to lead to some extent to increases in crop prices, which in turn may be expected to stimulate displacement of crops and agricultural expansion into natural areas and management intensification in semi-natural agricultural habitats, both within the UK but also abroad. It is unclear to date what, if any, indirect land use changes are occurring within the UK as a result of increased biofuel production. However, spatial modelling on the consequences of direct and iLUC as a result of increased EU demand for biofuels has been undertaken and this is discussed in relation to international impacts below. To our knowledge, there are no studies that have spatially modelled the impacts of increased UK demand explicitly. Potential mitigation measures Since the impacts from agriculture are: (1) dependent on the sensitivity of the former land-use; and, (2) very dependent on the management practices, they can be most effectively mitigated through avoiding biofuel production and iLUC on the most biodiverse and sensitive areas. In addition, environmentally sensitive land management practices can help to maintain biodiversity levels within biofuel production areas and reduce external impacts on other habitats. These include the use of native species that reduce the needs for irrigation, fertilisers and pesticides, ground cover crops, reduced tillage, cover crops and the use of green manure over-winter to reduce soil erosion. Soil functionality can for instance be significantly improved with the application of appropriate management practices (Cooper et al., 2009). Post-harvest management also varies significantly and can include ploughing-in of crop residues, such as straw, to improve soil functionality (Nowicki et al., 2009). Stubbles can be left over winter (also paid for under certain agri-environment schemes) or they can be ploughed immediately post- harvest leaving a bare soil (these will however also impact how much biofuel can be derived from the crops). The use of crop residues as animal feed can also make a significant contribution to reducing direct and indirect land use change. Kampman et al (2008) estimate that 60-81% of the net land requirements per tonne of biofuel could be reduced by making full use of the potential feed displacement effect. However, such displacement relies on the price of such by-products being lower than traditional feeds in order to incentivise a change from the known status quo and again will have impacts on soil processes. More precise and careful application of fertilizer can result in reduced run-off without compromising yields. The most important biodiversity impacts are likely to arise from iLUC outside the UK (see next section). In the UK, suppliers are required to submit reports under the RTFO on both the net GHG saving and the sustainability of the biofuels they supply in order to receive Renewable Transport Fuel
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Certificates (RTFCs). Given the limited data availability and the absence of comprehensive internationally agreed standards, this reporting framework was designed to test the robustness of the RTFO criteria as a first step to towards a mandatory assurance scheme. The RTFO reporting scheme is based on a ‘Meta-standard’ approach which has seven principles including that biomass production will not lead to soil degradation, the destruction/damage of high biodiversity areas or the contamination or depletion of water resources. In 2011, none of the accredited available standards met all of the principles of the Meta-standard. Suppliers are allowed to nonetheless organise additional supplementary checks to demonstrate that the feedstock complies fully with the Meta-Standard criteria. In December 2011, the UK RTFO was amended to be in line with the EU sustainability criteria for biofuels and bioliquids that were introduced as part of the Renewable Energy Directive. These are meant to ensure that biodiversity-rich areas as well as high-carbon stock areas such as forests or peatlands are not converted to cropland to grow biofuel feedstocks. While these regulations are important to allow for more careful siting of biofuel crops, they do not mitigate against iLUC risks, because other crops are not banned from these areas (i.e. the biofuels will be grown on current agricultural areas, resulting in the crops formerly grown on these areas being displaced to e.g. deforested/drained areas). The Gallagher Review (RFA, 2008) recommends that biofuel expansion in the UK is targeted on idle and marginal land to limit its impact in pushing up global crop prices and resulting in iLUC. However, this would have potentially high biodiversity impacts as marginal land in the UK is often semi-natural habitat of relatively high biodiversity value.
1.9.4 International biodiversity impacts and their mitigation
Potential impacts As mentioned above, the main impacts from crop-derived biofuels result from the encroachment in natural, biodiversity-rich areas, and their fragmentation. As many biodiversity hotspots are found in countries in which biofuel crops are expected to expand (Koh & Ghazoul, 2008), the biodiversity impacts are likely to be high in those countries. In addition, the lack of incentives and low protection regimes mean those areas are vulnerable to land conversion (reported in Campbell and Doswald, 2009). The main sources of international biofuel feedstocks supplied to the UK are soya bean from Argentina, sugar cane from Brazil, maize from the US and oilseed rape from the EU. Projections for the future provenance of biofuels consumed in the UK were not found during this study. Nonetheless, several model projects have begun to spatially map direct and indirect land use change as a result of increased demand at the EU level (Böttcher et al, 2012; Hellmann and Verburg, 2011; Laborde, 2011), which are discussed below. A brief discussion is also provided of the known impacts of direct land use change associated with the most important biofuel imports to the UK. Direct land use change According to Sparovek et al (2007) the expansion of sugarcane production in recent years has occurred primarily in São Paulo state; and of the land converted to sugar cane between 2007 and
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2008, 45 per cent was previously rangeland (Zuurbier and van de Vooren, 2008; cited in Bertzky et al, 2011). Similarly Sawyer (2008) reported encroachment by sugar cane in the Brazilian Cerrado, the world’s most biodiverse savannah. Soy is also increasingly used to make biodiesel, and plantations expand in Brazil in the Cerrado and Amazon rainforest. Land-use change in the US and other developed countries are reported to be the result from shifts in production types and some even use these arguments to negate iLUC (see for example O’Hare et al, 2011). Although a relatively small percentage of UK biofuel is derived from palm oil, the development of palm oil plantations has very high biodiversity impacts. An estimated 27% of oil palm concessions displace peatland rainforest and an estimated 55-59% of oil palm expansion in Malaysia, and 56% in Indonesia occurred at the expense of forests (reported in Campbell and Doswald 2009). Since peatland forests are considered to include a very high biodiversity, important negative impacts result from such encroachment. While impacts from palm oil plantations are well documented in South-East Asia, they are also reported to deforest areas in, e.g. Colombia, Ecuador, Brazil, Central America, Uganda and Cameroon (AEA, 2008).
Impacts from agricultural practices The results presented below are reported in Campbell and Doswald (2009). As in the UK, agricultural practices used for growing biofuel crops will result in differentiated biodiversity impacts. In general, biofuel plantations are intensive monocultures, with low species diversity and high soil erosion. Only 15% (e.g. medium to large mammal species) to 22% of species recorded in primary forests are found in palm oil plantations (e.g. 72% reduction or arthropods). These plantations support lower levels of biodiversity than other tree crops, agricultural crops and abandoned pastures. In addition, those species lost are generally specialist species with high conservation concern. Similarly, results in sugar cane-dominated watersheds show an increase in generalist species, and absence of mammals typical for intact forest. Sugar cane plantations are also reported to result in high soil erosion, and reduce the original riparian vegetation, resulting in lower richness of small mammals. Corn-based ethanol in the USA is reported to have the highest impacts compared to other agricultural crops, due to its high fertiliser and pesticides requirements. Corn is often irrigated, which also impacts riparian and aquatic wetlands if it results in lower water availability. More generally, water is expected to be an important limiting factor to the cultivation of biofuel crops, especially as agriculture is already the highest water user worldwide, and may increase issues of scarcity and droughts, with negative impacts on biodiversity, but more broadly also on human populations. Many of the species recorded in abundance in plantations are invasive and replace important species for ecosystem services (e.g. pollinators). Biofuel crops also risk becoming invasive in the environments surrounding the planted areas. Indirect land use change
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iLUC is expected to occur mainly outside of the UK, resulting from the global market responses to increased demand for biofuels, continuous demand for food and other uses of crops (e.g. palm oil is used for shampoos, etc.). iLUC cannot be directly assessed, as it involves a complicated causal chain and is generally modelled to understand the difference between a scenario with higher biofuel demand and a scenario without that demand. A recent study by Laborde (2011) contains the most recent and widely accepted set of modelling results on the estimates of the scale and location of land use change, both direct and indirect, as a consequence of the RED up to 2020. This shows the impacts from overall biofuel use in the EU increasing from 11.7 Mtoe in 2020 in the baseline to 27.2 Mtoe in 2020 in a biofuel policy scenario that is in line with the anticipated biofuel use according to the EU Member States’ National Renewable Energy Action Plans. Without trade liberalisation (i.e. business as usual trade policies), the EU is expected to experience land area extension for the production of sugar beets due to support from Member States for bioethanol production, while under trade liberalisation, a greater proportion of rapeseed is grown in the EU at the expense of sugar beet and cereals. Globally, the additional biofuels mandate leads to an increase in cropland of 1.73 million hectares without trade liberalisation or by 1.87 million hectares with trade liberalisation. The most affected regions are Latin America (primarily Brazil), the Commonwealth of Independent States (CIS) and Sub-Saharan Africa. Cropland extension in the EU is expected to be 6 per cent under either scenario. Under trade liberalisation, Brazil experiences the highest increase in cropland, primarily for sugar cane due to an increase in demand for imported ethanol. If trade liberalisation is not implemented, there will be a shift of bioethanol production to eastern European states of the CIS primarily through sunflower and wheat. It is expected that 80 per cent of the land use change occurs within managed land in both scenarios. The principal sources of cropland extension are pasture and managed forest, followed by savannah and grasslands and finally primary forest. The biodiversity impacts from these LUC will be different, with highest losses resulting from primary forest and lower from pasture and managed forests. The impacts from iLUC are as for direct land-use change, the encroachment of crops in biodiversity-rich areas (which may be a perverse effect of banning development of biofuel crops in such areas), fragmentation and impacts on biodiversity of cultivation practices (as seen above, e.g. soil erosion, soil and water pollution, etc.). Recently, much research has focused on the effects of iLUC on GHG emissions, with controversial results showing that the iLUC impacts of biofuels could negate the GHG benefits of low carbon technologies. Since climate change has impacts on biodiversity, it is important to take these into account. In addition, the results are based on conversion from forests and peatlands to agricultural lands, ecosystems that not only stock carbon, but are also biodiversity-rich. Potential mitigation measures Modelling results from Böttcher et al (2012) show that the probable most effective means of minimising the adverse impacts of iLUC is effective protection (and enforcement) of areas of greatest ecological importance. This needs to be implemented globally, however, as new restrictions on expansion in Europe, for instance, could result in greater iLUC pressures in developing nations with severe biodiversity consequences. Similar to what occurs in the UK, ensuring that biodiversity-friendly practices are implemented will ensure reduced negative impacts from biofuel crops. In addition, and more specific to
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international cultivation practices, avoiding the burning of crop residues, the use of fire, agroforestry systems and including plantation areas to be set as natural reserves will avoid negative impacts. There remains significant capacity to increase crop yields in developing countries, which would reduce demand for additional land (FAO, 2008). Nevertheless, this will be contingent on appropriate investments as well as supportive legislative and trade agreements (RFA, 2008). The State of Food and Agriculture study (FAO, 2008) demonstrated that despite a significantly lower baseline, yield increases between 1992 and 2002 from middle and lower income countries were only marginally higher than in high-income nations, most likely due to an absence of these conditions. A trade-off will occur between intensification and reduced land encroachment. Some advocate intensification since the most negative impact is conversion of biodiversity-rich areas to agricultural areas, but this could result in negative environmental impacts that are not limited to the cultivation area (through e.g. leaching and reduced water availability). Careful land-planning is suggested to be the best mitigation measure.
1.9.5 Conclusions
Summary of known impacts The biodiversity impacts from crop-derived biofuels are probably amongst the highest of the energy technologies, and will have the highest impacts outside the UK. The direct impacts of biofuel production will depend on what was grown previously and the biodiversity present after conversion. In the UK, it is expected that most, if not all, bioenergy crops for biofuels will be grown on existing productive agricultural land. Biodiversity losses may therefore be expected if it results in land use change from pasture (especially extensive systems on semi-natural habitats) to arable or increased intensification. How biofuel crops are managed will also have impacts on biodiversity. By far the biggest biodiversity impacts of biofuel demand from the UK will be land use change impacts, especially indirect land use change (iLUC) impacts. The sustainability criteria in the EU Renewable Energy Directive (RED) aim to ensure that biodiversity-rich areas as well as high- carbon stock areas such as forests or peatlands are not converted to cropland to grow biofuel feedstocks. This should reduce direct land use change impacts to some extent, but this does not prevent iLUC. The challenge with assessing the impact on biodiversity of biofuel crops is that it is difficult to say where indirect impacts take place. EU studies summarised above have pointed at Brazil, Ukraine and Sub-Saharan Africa as the main geographic regions where displacement effects can be expected, but studies focusing on the biofuel imports to the UK are lacking. Nevertheless, the fact that ilUC takes place has been demonstrated and given the large volume of UK anticipated biofuel use (according to its National Renewable Energy Action Plan), substantial impacts on biodiversity can be expected from biofuel imports. These impacts will result from conversion of previously highly biodiverse areas (occurring mostly in the countries in which biofuel cultivation is expected) to agricultural land.
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It is difficult to determine the extent of iLUC, but the best mitigation measure is through the protection of areas of high biodiversity value, for instance through the standards set in the RED. However, to effectively tackle iLUC such protection needs to be extended to impacts from all landuses. In addition, ensuring that agricultural management practices are as biodiversity- friendly as possible will help mitigate some impacts. These include reducing iLUC through increasing yields, the utilisation of crop residues, and the integration of cattle and cropping. A more elaborate discussion of potential mitigation measures occurs in Chapter 6 of the final report. Knowledge gaps and required research The main knowledge gap regarding the impacts of biofuels in the UK on biodiversity is the impact of iLUC of crops grown in the UK, and the direct and indirect impacts of biofuels and feedstocks imported to the UK from abroad. However, this is difficult to assess because biofuel feedstocks are traded as an international commodity, which makes it difficult to determine where they are produced – and more specifically how the crops where grown and whether this involved detrimental land use change. Table 19: Summary of potential biodiversity impacts per unit of energy produced from the use of crop-derived biofuels for UK energy requirements
Selected Crop-derived biofuels technology
Impacts in UK
Positive impacts None likely to occur, except rarely when grown on bare and badly degraded land
Direct mortality Low/Moderate: Possible impacts on birds or small mammals during harvest, impacts from soil management on soil biodiversity
Direct habitat loss Moderate: More likely to displace existing agricultural land uses
Indirect habitat Uncertain. More likely to occur outside the UK through iLUC degradation
Disturbance Low: Particularly if on already cultivated areas, disturbance through soil management and other agricultural practices possible
Secondary impacts Low: Enhanced agricultural economy may lead to investment and wider agricultural improvement and intensification
Potential for Moderate: Use of marginal semi-natural land attractive to investors, but mitigation currently constrained by agricultural policies and regulations. Management measures can reduce within crop and external impacts
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Selected Crop-derived biofuels technology
OVERALL MODERATELY DETRIMENTAL RESIDUAL IMPACTS
Potential for Moderate: through restoration of degraded semi-natural habitats or ecological protection and management of threatened semi-natural habitats compensation
Impacts outside the UK
Positive impacts None likely to occur, except when grown on bare and badly degraded land
Direct mortality Low: Possible impacts on birds or small mammals during harvest, impacts from soil management on soil biodiversity
Direct habitat loss High: Due to LUC if not effectively prevented by sustainability criteria. Rangeland loss in Argentina and Brazil, deforestation, drainage of wetlands, conversion of peatlands, which are highly biodiverse areas, but measures to reduce direct LUC can be implemented
Indirect habitat High: Particularly as a result of iLUC. Pasture, managed forest, followed by degradation savannah and grasslands most at risk.
Disturbance Low: If on already cultivated areas, disturbance through soil management and other agricultural practices possible
Secondary impacts Moderate: Enhanced agricultural economy may lead to investment and wider agricultural improvement and intensification
OVERALL HIGHLY DETRIMENTAL RESIDUAL IMPACTS
Potential for Uncertain: Protection of primary forests and highly biodiverse areas mitigation through RED regulation, but unlikely to be effective in reducing iLUC
Potential for Low for impacts on natural habitats, through protection and management ecological of threatened areas; moderate, for semi-natural habitats through compensation restoration of degraded areas
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1.10 Biomass from dedicated energy crops and primary wood production
1.10.1 Overview of the technology
Dedicated energy crops refers to crops that are not grown for food but for energy use only. It includes perennial energy crops such as tall rapidly growing grass with high lignin content (e.g. Miscanthus, Canary Grass and Switch Grass), Short Rotation Coppice (SRC) of fast growing trees (e.g. willow or poplar) and oil crops such as Jatropha. Biomass derived from these sources can be used in heat and electricity generation and other applications. While SRC crops are most productive on higher grade lands, poor grade land (e.g. that which is low in nutrients or prone to waterlogging) can also produce high yields, particularly in areas with high rainfall or high soil water availability (Aylott et al, 2008; cited in Aylott et al, 2010). This can make SRC crops economically viable on land not used for food crops. Advanced or second-generation conversion processes have recently been developed that allow biofuels to be produced from ligno-cellulosic biomass, which can be used as transport fuels. A number of demonstration projects are in operation, but they have not yet been deployed commercially. Most analyses (for example, OECD and FAO, 2011) remain cautious about the medium-term potential of second generation biofuels market availability, and only expect this to be realized in the latter part of this decade. Their penetration into the market depends on the advancement of R&D, the level of investment attracted and the continuation of proactive policy frameworks. As the technologies become available, they are likely to compete with food and fodder crops as a liquid biofuel stock (CCC, 2011). Figure 21: Processing steps in ligno-cellulosic ethanol production
Source: Bacovsky et al, 2010, p16 in Kretschmer et al 2012) Primary wood production refers to biomass harvested from new and existing conifer or broadleaved woodlands. It can be used to produce woodfuel and pellets from timber that is often of superior quality to that from other forestry operation (such as short rotation coppice) or from arboricultural arisings and wood waste and therefore burns more efficiently (Kretschmer et al, 2011).
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1.10.2 Use in the UK
Dedicated energy crops As of 2009, dedicated energy crops accounted for less than 0.1% of the UK and electricity markets (Aylott et al, 2010). In 2011, 8 075 ha of Miscanthus62 and 2 720 ha of short rotation coppice were grown for bioenergy production in England (Defra 2013). This means that around 0.2% of the total arable area in England was used for growing these crops in 2011. Bioenergy crop areas are not available for Scotland and Wales. Almost all the short rotation coppice production (15,000 tonnes) was used in power stations for electricity generation in 2010/11, but only half of the Miscanthus production (40,000 tonnes) went to electricity. The rest of the Miscanthus was probably used in small scale Combined Heat and Power (CHP) plants or directly on farms or domestic premises for heating but the volumes used are not available. SRC is harvested every 3-4 years (or more recently, every 2-3 years). Miscanthus matures at 5 years and can then be harvested for 15-20 years (Defra, 2013). Much of the land identified as being suitable for growing biomass crops by the ongoing Relu- Biomass project is currently used for growing arable crops and therefore has the potential to create conflict between land required for energy and that required for food (Lovett et al 2009). Nevertheless, Aylott et al (2010) estimate that 7.5 million tonnes of biomass could be realistically produced in England on poor quality marginal lands, which would not compromise food production or other ecosystem services. This would require 0.8 Mha of land and would contribute approximately 4% of the UK electricity demand. Other studies have estimated the theoretical maximum land area available to perennial crops at 0.9 Mha, 1 Mha and 3.1 Mha (Andersen et al, 2005; BERR, 2007; Gill et al, 2005 (all cited by Aylott et al, 2010); Haughton et al, 2009). Constraints mapping by the Relu-Biomass project (Haughton et al., 2009) which eliminated land classified as inappropriate suggested that 39% of the land area of the East Midlands and 17% of the South West regions could be suitable for energy crop planting, giving an overall area of 3.1 million ha. Nonetheless, the level of supply of bioenergy crops is likely to be considerably below this. Howes et al (2011) estimate that UK energy crops will comprise approximately 3.6% of the UK biomass usage in 2020 (421,200 Mtoe). Primary wood products UK woodlands and forests currently produce around 10 million green tonnes of wood each year, which is supplying a range of markets including sawmills, panel board producers and energy generation. Woodfuel delivered to energy markets has increased significantly from around 0.5 million tonnes of wood in 2007 to 1.5 million tonnes in 2010 (DECC, 2012)63. Biomass electricity capacity in the UK was 2.5 GW (including 0.4 GW of co-firing), most of which was produced from landfill gas. The UK Renewable Energy Roadmap64 projects that biomass electricity could contribute up to 6 GW by 2020, equating to an annual growth of 9%. RSPB
62 7 465 ha Miscanthus was grown in 2008
63 UK Wood Production and Trade, 2011
64 http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/renewable-energy/2167-uk-renewable-energy- roadmap.pdf
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(2011) estimate that the projected increase in biomass electricity from 2.5 GW to 6 GW by 2020 (see DECC, 2010b) would require an equivalent of approximately 36 million oven dried tonnes (odt) of wood in 2020 compared to the demand in 2010 of 15 million odt65. A further 10 million odt would be required to meet demands for biomass heat sector in 2020. In addition, the amount of residual waste from municipal and commercial sources is expected to decline gradually to 2030 as policies to encourage better environmental and energy outcomes succeed. As most of the current 2.5 GW of biomass electricity is produced currently from landfill gas, this future phase- out will create a further pressure on other biomass sources in order to maintain biomass electricity production levels.
1.10.3 UK biodiversity impacts and their mitigation
Potential impacts Dedicated energy crops The increasing body of evidence of the potential negative impacts of crop-derived biofuels (see above) has resulted in a greater interest in the use of dedicated energy crops to meet renewable energy targets. Energy crops can be used on low quality land unfit for food growing (such as on low nutrient soils or land prone to flooding) and therefore do not necessarily compete with food for agricultural land. A significant advantage of the perennial species is the reduced disturbance to soils and longer periods for species to establish. Typically, crops remain in situ for 7-25 years (Haughton et al., 2009). This can have a number of environmental benefits including increased water retention, reduced soil erosion (International Energy Agency, 2010), and an increase in ground cover which is beneficial to biodiversity. In addition, energy crops typically use very few agrochemical inputs, compared to most crop-derived biofuels (Biemans et al, 2008; Haughton et al., 2009). The main environmental issue associated with the use of these energy crops concerns the increased competition for agricultural land (Kretschmer et al, 2011). The overall impact will depend primarily on where the crop is sited. Field studies show expected biodiversity benefits if energy crops replace intensive farmland (arable crops or grassland), although the intensity with which the replaced arable/grassland was managed can have an effect on the apparent benefits of perennial crops (Cunningham et al., 2006; cited in (Birdlife International, 2011)). Of concern is the pressure to site energy crops on less productive land, potentially resulting in a loss of semi- natural habitat such as wet grasslands, calcareous grasslands and heathlands, many of which are UK BAP Priority Habitats. The conversion of permanent pasture, for instance, to energy crop production is likely to result in negative impacts for biodiversity and soil carbon stores. Farmers are already growing bioenergy crops on a relatively large scale. Almost three quarters of the Miscanthus is being grown in blocks of at least 20 ha, a third covering at least 50 ha (Defra, 2013). SRC is being grown on a smaller scale, with around half of the crop in blocks of at least 20 ha, and one third of growers with only 2 ha or less.
65 Calculated using figures in the UK NREAP (as cited in footnote 3) and a conversion factor of 6,000,000 odt/GW (SQWenergy: Renewable and Low-carbon Energy Capacity Methodology, Jan 2010)
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Knowledge of the impact of perennial grass crops is limited due to the small number of field trials that have been carried out. Results from those that have been conducted suggest that Miscanthus attracts greater species diversity and abundance than arable crops for flora, invertebrates, birds and mammals (Semere and Slater, 2005; 2007a; 2007b; Bellamy et al., 2009; Rowe et al., 2009; Smeets et al., 2009; cited in (Birdlife International, 2011)). However, all of these results are from immature Miscanthus plots (less than five years old) with poorly established and weedy crops. More established crops are likely to shade out weed flora that in turn will limit related species that depend on the ground cover from weeds. As farmers improve their cultivation techniques, crop density is likely to increase, which will further reduce its attractiveness for wildlife (Birdlife International, 2011). Research by Sage et al (2010) on the use by birds of Miscanthus led the authors to conclude that the use of the sites by birds is likely to be influenced by field conditions such as weediness, patchiness, crop structure as well as regional differences. Short rotation coppice (SRC) similarly appears to support higher biodiversity (abundance and diversity of species) than arable and improved grassland. A comparison of the abundance of families of butterfly in field margins of Miscanthus and SRC willow compared to arable crop breaks found that abundance was significantly higher in field margins surrounding Miscanthus and SRC willow (60% and 132% more butterflies respectively) than in arable crops (Haughton et al, 2009). Other studies suggest that there is a greater abundance of butterfly families containing species of intrinsic conservation interest in the field margins of energy crops than in those of arable crops (Asher et al 2001; cited in Haughton, 2009) while not acting as a source of economically harmful pest species such as Pieris brassicae. Sage et al (2006) found greater density and number of bird species in SRC than in arable land, particularly benefitting scrub and woodland species. This includes a somewhat limited number of species of high conservation concern, including Bullfinch (Pyrrhula pyrrhula), Reed Bunting (Emberiza schoeniclus) and Song Thrush (Turdus philomelos) (Defra, 2006; EEA, 2006; Sage et al, 2006; cited in Birdlife International, 2011), which have been demonstrated to hold territories in the breeding season. SRC also provides winter cover for species such as Woodcook (Scolopax rusticola), Redwing (Turdus iliacus) and Fieldfare (Turdus pilaris) (Sage et al, 2006). Most of these studies have been carried out on relatively small or isolated areas of bioenergy production and to date no studies have looked at the cumulative impact of large regional developments of energy crop mono-cultures, which may be necessary to supply large power plants. The result of such developments could be displacement of farmland species and open- field specialists, such as Yellow Wagtail, Skylark Alauda arvensis or Grey Partridge (Bellamy et al 2009; cited in (Birdlife International, 2011)) and could reduce or even reverse the positive benefits of replacing arable crops. Benefits are expected for soil quality and organic carbon content but these will be highly site specific and dependent on the previous land use. Substitution of cropland by SRC crops is likely to increase soil carbon due to reduced frequencies of soil disturbance. The impacts of replacing pasture with SRC are less clear and are likely to depend on the relative balance of nutrient inputs and the decomposition rate of deposited materials (Cowie, 2006; cited in International Energy Agency, 2010). Given the high nutrient content of leaves and bark, whole tree-harvesting will
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remove greater amounts of nutrients than stem-only harvest. This impact can be reduced if harvesting takes place in winter after leaves have already fallen (for deciduous crops only). Primary wood products The UK is amongst the least densely forested areas in Europe with approximately 3.1 million hectares of forest or 13% of the land surface area (Forestry Commission, 2012). The creation rates of woodland in the UK has slowed in recent years: between 1990 and 2000 the rate of woodland creation was between 18-21,000 hectares annually; while the current rate stands at approximately 8,200 hectares per year (Forestry Commission, 2012). Most of this is on land outside the public forest stand and would probably decline further without public funding (Independent Panel on Forestry, 2011). In addition, only just over half (52%) of woodland in the UK is under active management (Forestry Commission, 2011). A recent review of government policy highlights the importance of finding sustainable private sources of financing to ensure woodland maintenance and creation (Independent Panel on Forestry, 2011). The wood used for bioenergy can be harvested from existing woodlands or, in the future, from newly planted coniferous or deciduous woodlands. The establishment of new areas of woodland could present a number of significant opportunities for biodiversity by increasing the area of habitat suitable for woodland species, reducing soil erosion and improving connectivity. The strategic location of new woodland can add areas of woods where the habitat is under- represented or increase ecological connectivity. The placement of woodland in areas where climate is expected to change may be used to facilitate the adaptation of species vulnerable to climate change (Gove et al, 2010). The thinning and clear-felling of some areas within woodlands may create extra habitat for species preferring mixed forestry and semi-open areas while decreasing the habitat for closed canopy species. A significant determinant of the potential impact of the use of this feedstock and the creation of new woodland is the previous land use (which may be of high biodiversity value) and the displacement of previous land use to other areas. Furthermore, there may be important negative biodiversity implications if woodland creation is composed of non-native coniferous stands, particularly in areas with previously high biodiversity. Further issues include soil erosion following clear-felling (particularly areas on slopes or uplands) and a decrease in species associated with old-growth trees. The Forestry Commission Woodfuel Implementation Plan states that woodfuel works best on a sub-national scale – using locally grown fuel in efficient, modern boilers as a clean way to provide heat for business and community buildings, saving money and CO2. GHG implications from burning biomass There is increasing debate about the potential of bioenergy use to reduce GHG emissions, most notably when it comes to using woody biomass. The emission reduction potential from bioenergy crucially rests upon the fact that the burning of biomass is considered carbon neutral given that the carbon that is released is absorbed during plant growth. This assumption is very problematic given that it may take decades for the carbon to regrow (McKechnie et al, 2011) and furthermore the GHG balance is impacted further as one reduces the sequestration potential of the biomass. The fact that burning biomass causes GHG emissions that are only ‘paid back’ later
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in time through regrowth has been described as the carbon debt problem. Bowyer and Baldock (2012) investigate this issue in more detail. Potential mitigation measures Given the importance of the siting of energy crops and the potential to create indirect land use change, the Gallagher review (RFA, 2008) recommends that only marginal land (i.e. land unsuitable for food production due to climate or poor soils, or areas that have been degraded, such asthrough deforestation) should be used for energy crops. However, many authors report the difficulty to define marginal land, that yields would be higher on more productive lands, needing incentivisation of that use and the difficulty to regulate the uses made (e.g. see Campbell and Doswald 2009). BirdLife International (2011) call for the development of local guidance to ensure that the most important areas for biodiversity are avoided and that biodiversity constraints at a local or regional level are not exceeded. There appears to be an opportunity to enhance positive effects of energy crops on biodiversity by careful planning, planting of the right crop in the most appropriate location and with considered management (Gove et al, 2010; cited in (Birdlife International, 2011). Much of the biodiversity associated with farmed land is found at the boundaries and the margins (Semere and Slater, 2005, 2007; cited in (Birdlife International, 2011)) and therefore a patchwork of relatively small plantations mixed with arable and grass crops could lead to biodiversity benefits (Cunningham et al 2006; Defra, 2006; cited in (Birdlife International, 2011)) However, care would need to be taken to avoid impacts on areas of importance for species that are dependent on open agricultural habitats. Robust sustainability certification schemes should also be introduced to ensure that energy crops are produced in a biodiversity-friendly manner. Nevertheless, there will have to be effective enforcement of the schemes regarding the siting, planting, management and harvesting activities. Strict guidelines on catchment management will have to be enforced to ensure that large-scale bioenergy plantations do not adversely affected water resources (Rowe et al, 2007).
1.10.4 International biodiversity impacts and their mitigation
Potential impacts Dedicated energy crops No complete figures are currently available on how much dedicated bioenergy crops is currently imported. In a review of the potential sourcing of energy crops for UK consumption, the CCC (2011) estimate that only a small proportion of abandoned agricultural land globally will be available for the growth of dedicated energy crops, without relaxing sustainability constraints to prevent the conversion of natural habitats or planting on land currently used for food crops (which could result in indirect land use change). It is also unclear whether growing dedicated energy crops would be economically viable, given the limited experience to date. Therefore, it is unlikely that imported energy crops will be a significant energy source for the UK in the near to medium-term future.
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The ability of bioenergy crops to grow on abandoned or poor quality land not suitable for food crops means they have the potential to provide significant rural development opportunities and improve socio-economic conditions in emerging and developing regions. Their impacts on biodiversity, on the other hand, remain unclear and are related to how and, particularly, where they are produced. The principal biodiversity concern about bioenergy crops is land use change (see crop-derived biofuels above). Increased demand for energy crop biomass could either lead to direct land use change, where areas of high conservation value are converted to mono- cultures of energy crop, or indirect land use change by utilising land previously used by agriculture and thus displacing agricultural activity into natural areas. This is a particular concern in developing regions that have large areas of high conservation value but often do not have sufficient safeguards in place to prevent their destruction. While few data exist on the biodiversity impacts of growing energy crops, there are a number of concerns about their suitability in emerging and developing countries. To date, most of the development has taken place in developed nations and there is a lack of research on high- yielding breeds of crops that are adapted to local conditions (such as water shortages and pests), particularly in Asia and Africa (International Energy Agency, 2010). In addition, there are concerns that the plant species currently used in developed nations have the potential to become invasive when they are introduced into environments where they are not native, with negative impacts for natural ecosystems. Further research is required to identify appropriate breeds of energy crops, and this could take several decades. There are also concerns that the water requirements for the energy crops could exacerbate water pressures in developing and emerging regions. Although initial studies appear to suggest that the water requirements are approximately the same as those for arable crops, the growing demand for biofuels worldwide will result in the planting of bioenergy crops in areas not previously cultivated, therefore increasing demands on water resources. Nevertheless, compared to first generation biofuel crops or arable crops, they are likely to provide a number of benefits. For instance, as they require considerably lower fertiliser inputs, they will exert a lower pressure on water resources through water pollution. The potential of perennial crops to reduce soil erosion (from water and wind) is likely to be particularly advantageous on vulnerable soils (such as loess plateau in China or tropical soils in Thailand (International Energy Agency, 2010)).
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Supporting document – Literature review on impacts on biodiversity
Primary wood production An increase in demand for wood and forest material is likely to have a greater impact on biodiversity outside the UK than within the UK. The increasing demand for forestry products for bioenergy use through the establishment of biomass plants in the UK creates a demand for biomass (including virgin wood) that cannot be met domestically. RSPB (2011) estimate that if all plants currently proposed were to be built, a total of 48.3 million tonnes of biomass would be needed to fuel UK biomass plants; 9.3 times the current figure used annually. This is expected to be dominated by imports, requiring a total of 39.1 million tonnes of imported biomass. This would certainly create an unsustainable demand for wood that will be required to run existing and new build plants for several decades. Increased demand could therefore contribute significantly to global deforestation pressures and lead to an increase in the logging of existing virgin stands of forests. Alternatively, the demand could be met by new plantations that can have negative implications for biodiversity depending on previous land use. While the UK has a regulatory framework to reduce the negative impacts of forestry, many countries do not have equivalent protection and cannot guarantee the sustainability of wood. In addition, it may result in the removal of dead wood and stumps that may otherwise have been left over after timber extraction (RSPB, 2011). Potential mitigation measures Dedicated energy crops Without appropriate regulation, higher levels of energy crop penetration might ensue under a market-based approach and a rising carbon price with negative impacts on food supply, biodiversity and soil carbon. Therefore in order to limit dedicated energy crops to appropriate levels, new regulatory arrangements would have to be introduced such as limiting the types of land on which dedicated energy crops can be grown, and the extent to which these can be used to meet carbon targets. The Gallagher Review (RFA, 2008) recommends that the European Commission proposes a technology-neutral approach within the EU Renewable Energy Directive to incentivise second-generation biofuels (i.e. advanced technologies), focussing on feedstock type and type of land on which it has been produced. To address international concerns, the CCC (2011) recommends that the UK maximises UK its supply of energy crops given that there is generally more certainty about the sustainability of UK- grown biomass. Greater investment is also required in Asia and Africa to develop high-yielding indigenous ligno-cellulosic crop species that are adapted to local conditions and do not pose a threat of becoming invasive. However, this research could take several decades and is not a likely to have an impact in the short- to medium-term. In some countries, such as India and Thailand, the pressure on croplands is already so high that any expansion of bioenergy, including energy crops, will require very detailed planning (International Energy Agency, 2010). New genotypes with high water efficiency will be required to reduce water stress and catchment scale management must be in place (Rowe et al, 2007). Feedstocks that do not require irrigation should be given priority in areas where access to freshwater is restricted. Primary wood production
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In the UK there is a reasonably comprehensive regulatory framework ensuring the sustainability of woodland creation. The UK Forestry Standard (UKFS) is mandatory and sets standards for good practice for forestry in the UK while the voluntary UK Woodland Assurance Standard (UKWAS) allows the use of domestic woodlands for bioenergy production management in a way that benefits wildlife. Nevertheless, there are concerns about the continuing practice of plantations on priority open ground habitats such as lowland heath and blanket bog (RSPB, 2011). Greater rigour and quality of auditing for UKFS compliance and more stringent requirements with respect to former land use are required (RSPB, 2011). To solve international biodiversity concerns, the CCC (2011) recommends that serious consideration be given to introducing a sustainability standard for all wood used in the UK (e.g. pulp and paper, construction) which would ensure that biomass in power does not result in indirect deforestation. This is supported by the RSPB, which supports the imposition of FSC requirements to imports. The UK Bioenergy Strategy (DECC, 2012) accepts that current sustainability criteria will need to be more stringent, but implemented in a way that allows the supply chain to respond; and so it remains to be seen whether these criteria will be sufficiently rigorous to prevent contributing to deforestation pressures. Site-by-site investigation into the susceptibility of forests to erosion needs to be undertaken. Similarly, careful strategic assessment of placement is needed to avoid siting on areas of high biodiversity value or land that is required for other uses that may be displaced to areas of high biodiversity.
1.10.5 Conclusions
Summary of known impacts The production of energy crops has the potential to provide certain biodiversity benefits; initial trials appear to demonstrate benefits for multiple taxa compared to intensively managed arable land or heavily stocked grasslands. The main environmental issue associated with the use of these energy crops concerns the increased competition for agricultural land. Of particular concern is the pressure to site energy crops on less productive land, potentially resulting in a loss of semi-natural habitat such as wet grasslands, calcareous grasslands and heathlands, many of which are UK BAP Priority Habitats. In addition, field trials have not examined the impact of high concentrations of energy crops on a landscape scale, which is likely to be required to minimise production and transportation costs. The field trials have been carried in fields of relative immaturity and therefore with a lower density and greater levels of weeds which promote biodiversity. As the sites mature, and farmers become more experienced at maximising yields, the perceived biodiversity benefits relative to arable and grasslands may not materialise. Knowledge gaps and required research Knowledge of the impact of perennial grass crops is limited due to the small number of field trials that have been carried out. Most of the studies that have been carried out are relatively small or isolated areas of bioenergy production and to date no studies have looked at the cumulative impact of large regional developments of energy crop mono-cultures, which may be necessary to supply large power plants. Field trials have not taken into account the landscape
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Supporting document – Literature review on impacts on biodiversity
impacts of large areas of energy crops plantations on biodiversity, especially on open-field specialists. The impacts of replacing pasture with SRC are less clear and are likely to depend on the relative balance of nutrient inputs and the decomposition rate of deposited materials. Further studies are required on the long-term impact of large-scale SRC plantations on all species. There is also a general lack of data on the presence of biodiversity in mature Miscanthus and SRC sites, with greater crop density. For primary wood, the biodiversity implications are not well understood when woodland creation is composed of non-native coniferous stands, particularly in areas of previous high biodiversity. There is a lack of research on high-yielding breeds of crops that are adapted to local conditions (such as water shortages and pests), particularly in Asia and Africa. In opposition, there are concerns that the plant species currently used in developed nations have the potential to become invasive when they are introduced into environments where there are non-native, with negative impacts for natural ecosystems. Further research is required into the general potential impacts of the use of primary wood production on biodiversity, both within the UK and abroad. This needs to consider the extent to which use of primary wood for bioenergy may, directly and indirectly lead to deforestation, intensification of forest management (eg resulting in deadwood removal or replacement of native species with fast-growing species) and inappropriate afforestation. Table 20: Summary of potential biodiversity impacts per unit of energy produced from the use of dedicated energy crops for UK energy requirements
Selected technology SRC and Miscanthus and Primary wood production similar dedicated bioenergy crops
Impacts in UK
Positive impacts Variable depending on Variable depending on habitats replaced: habitats affected: thinning and reduced fertilizer clear-felling of some areas application and soil within woodlands may create erosion if replacing habitat for species preferring intensive arable crops. mixed forestry and semi-open areas.
Direct mortality Low: Some incidental loss during harvesting.
Direct habitat loss Variable depending on Variable depending on the habitat replaced. habitats affected. There is There is potential for potential for expansion of expansion of energy crops primary woodland on low on low grade land of little grade land of little biodiversity biodiversity value. value, but planting on semi-
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However, there is concern natural habitats would be that less productive, but damaging. Extensive clear- high biodiversity value felling of woodlands would land (such as permanent decrease the habitat for closed pasture) will be canopy forest species. converted.
Indirect habitat degradation Medium-to-high Possibly high: intensification potential: If demand for of management (eg removal energy crops displaces of dead wood and especially other land uses resulting replacement of native trees in conversion of semi- with fast growing alien natural habitats. species) would be highly damaging.
Disturbance Low: No increase in Moderate: Disturbance from disturbance compared to increased forestry operations. existing farmland.
Secondary impacts Low: Enhanced Low: New roads created for agricultural economy may forestry could increase activity lead to investment and because of easier access. wider agricultural improvement and intensification.
Potential for mitigation Medium: Enforcement of Medium: Enforcement of standards (for crops forest standards (eg covered by CAP) and mandatory UK Forest strategic land-use Standard and voluntary planning. standards) and strategic land- use planning and EIA for new woodland.
OVERALL RESIDUAL IMPACT MIXED MIXED
Potential for ecological Moderate: Restoration or Low: Not feasible for ancient compensation protection of threatened woodland, except through semi-natural grasslands. protection and enhancement of degraded areas.
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Impacts outside the UK
Positive impacts Low: UK unlikely to Variable: Depends on the import energy crop habitat and species. biomass in the short to medium term.
Direct mortality Low: see above Low: some incidental loss during harvesting, but unlikely to be significant.
Direct habitat loss Low: see above High: Potential to increase global deforestation pressures or new plantations, which can have negative implications for biodiversity depending on previous land use.
Indirect habitat degradation Low: see above Possibly High: As for UK
Disturbance Low: see above Moderate: As for UK
Secondary impacts Low: see above Uncertain.
Potential for mitigation Not required: see above Variable: depends on strength of legislation on the protection of biodiversity-rich land as well as its enforcement.
OVERALL RESIDUAL IMPACT LOW DETRIMENTAL PROBABLY HIGHLY DETRIMENTAL
Potential for ecological Not required: see above Uncertain, but probably as the compensation UK.
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1.11 Biomass from agricultural and forestry residues
1.11.1 Overview of the technology
Biomass from agricultural and forestry residues incorporates co-products and residues arising from agricultural cultivation and forestry practices. Agricultural residues include the dry by- products from crops such as wheat straw and seed husks. Although slurry and manure can also be considered as agricultural by-products (for example CCC, 2011), we include these under Genuinely Residual Wastes as their environmental and biodiversity impacts are more closely aligned to waste products. Forestry by-products includes woody material from existing forests (which may or may not be managed) as well as residues from saw-mills, forest floors and tree pruning. We also include in this section the arisings produced by habitat conservation and landscape management. This includes a range of vegetative material produced from the management, improvement and restoration of domestic landscapes, green spaces and habitats. Habitat management practices, for instance, can produce a regular supply of a range of biomass arising from the removal of conifers and invasive alien species (e.g. Rhododendron) from woodlands and semi-natural sites, and from the mowing of species-rich grasslands where grazing or hay-cutting is not feasible. Biomass arisings from this category can be used to generate energy through conventional technologies such as burning to generate heat and power or through advanced fermentation technologies that convert ligno-cellulosic materials into biofuels. Forestry residues originating from harvesting can be used as wood chips for generating heat in large scale boilers, whereas sawmill residues can be processed into high quality wood pellets and can be used in applications of different scales, including domestic boilers. The substances considered in this section therefore include: Dry agricultural residues: straw, seed husks, chicken litter Sawmill co-products Forestry residues: branches, leaf litter, coarse woody debris (often considered to be >10 cm width and >60 cm length, including standing deadwood or snags, and fallen logs). Arisings from habitat conservation: conifer trees, invasive alien species (e.g. Rhododendron), scrub, cuttings from grass, reed and bracken. Arising from landscape management: grass cuttings from public spaces, arboricultural arisings.
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1.11.2 Use in the UK
The potential energy production from this category is significant. Dry agricultural residues represent 17% of the estimated UK bioenergy potential in 2020 (1.98 Mtoe), while sawmill residues and forest by-products contribute a further 5% (0.55 Mtoe) and 2% (0.2 Mtoe) respectively (based on estimates from Howes et al, 2011). According to Howes et al (2011), straw makes up 75% of the dry agricultural residue potential in the UK (approximately 205 Mtoe) and therefore has significant potential as an energy source in the UK. Around 200 thousand tonnes of straw (approximately 2% of typical production) was used as fuel in biomass power stations in England in 2010/11 (Defra, 2013). Solagro (Solagro, 2010) estimate that under a business as usual scenario (taking into consideration CAP reform and market liberalization) the potential for crop residues66 from the UK to produce biomass for combustion or anaerobic digestion by 2020 is 2.75 Mtoe. Figures are not currently available regarding the amount of biomass arising from habitat management in the UK. The recent DECC methodology developed for English regions to estimate their renewable energy capacity omits arboricultural arisings, due to the difficulty in assessing the data (DECC, 2010c). Howes et al (2011) nonetheless estimate that arboricultural arisings could amount to 9% (or 1.09 Mtoe) of the UK bioenergy potential by 2020. At the EU level it is estimated that between 6-7% of the estimated overall agricultural bioenergy potential could come from cuttings from grasslands (EEA, 2006). However, it is very unlikely that the UK imports agricultural or forest residues from other Member States as the density of these residues makes the transportation costs prohibitive for bioenergy production.
1.11.3 UK biodiversity impacts and their mitigation
Potential impacts Dry agricultural residues Straw is considered to have lower environmental and biodiversity impacts than forestry and dedicated energy crops as it is not produced specifically for use as an energy resource (EEA, 2006; Kretschmer et al, 2011). The main concern with the use of straw as an energy source is the impact that its diversion to the energy sector could have on existing agricultural uses, with potential negative environmental consequences. In the EU, apart from its use as animal bedding and roughage, straw is commonly ploughed in to the soil after harvest to maintain soil functionality, such as reduced susceptibility to erosion by wind and water, more stable soil temperatures, more humid soil surface conditions; all of which may help to maintain soil fauna and biological activity in the soil. Normally around 60% of the straw produced can be baled and used for other purposes, the remaining stubble is incorporated back into the soil (Defra, 2013). Residual straw can also be added to pig slurry and cattle liquid manures, which can assist in locking excess nitrates to prevent leaching into water courses and can improve soil condition
66 Considered in Solagro (2010) to be straws from cereals and rapeseed, stalks and stems from sunflowers, green tops from potatoes, prunings from vineyards and trees.
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(Kretschmer et al 2012). Therefore, intensive straw extraction for energy production could result in the substitution of ploughed-in straw by non-sustainable options such as chemical fertilisers derived from fossil fuels, which could have negative consequences for soil functionality and soil biota. In addition, species that benefit from sparse cover and availability of seeds and split grain (including many farmland birds) may be adversely affected by the early ploughing in of stubbles to develop green cover crops (DBFZ and Oeko-Institute, unpublished).. Forestry residues Although it is not expected that the waste products from sawing mills should negatively affect biodiversity (Biemans et al, 2008), the removal of forestry waste products from forests could severely affect numerous species dependent on dead wood. Gove et al (2010) point to studies that show the removal of residues can negatively impact on a range of taxa including: fungi and detritivores (Lonsdale et al, 2008; all cited in Gove et al, 2010); microbial organisms (Kappes et al, 2007), bryophytes and lichens (Humphrey et al, 2002); invertebrates (Kappes et al, 2007); fungi (Ferris et al, 2000; Humphrey et al, 2000); saprophytic beetles (Humphrey et al, 2000; Jonsell et al, 2007); and small vertebrates, including bats (EEA, 2006; Forestry Commission, 2007). Many of the species, such as fungi and detritivores, provide vital ecosystem functions and are at risk (Lonsdale et al, 2008). Coarse wood debris (CWD) is particularly important to providing critical life-cycle functions such as breeding, foraging, basking for a variety of organisms. A meta-analysis of data from the US (Riffell et al, 2011) found that diversity and abundance of both cavity- and open-nesting birds were substantially and consistently lower in areas with lower downed CWD or standing snags. It found that the biomass of invertebrates (although not abundance) was also significantly reduced. The cumulative impacts for other taxa were not as large, and varied among manipulation types, although these were based on fewer studies. It remains unclear what scale of biomass harvest of forest residues results in significant biodiversity loss. In many cases, species and meta-populations dependent on deadwood require a particular density of CWD at different stages of decay, meaning that both qualitative and quantitative considerations are important (Lonsdale et al, 2008). Riffell et al (2011) suggest that the pilot biomass harvests to date report higher post-harvest changes in CWD than the experimental changes observed in the studies analysed. If this is the case, then operational biomass harvests may not change CWD levels enough to influence forest biodiversity. Nevertheless, deadwood specialist species are particularly sensitive to the removal of CWD and therefore likely to be a limiting factor on sustainable harvest levels. Biomass from habitat conservation There appears to be considerable potential for improving the ecological condition of many broadleaved woodlands through appropriate sustainable wood fuel production, as some 60 per cent of Britain’s ancient semi-natural and other semi-natural woodlands are currently undermanaged67. The lack of management is leading to detrimental impacts on a range of woodland species (Kirby et al 2005; Hopkins and Kirby, 2007). Some heathlands and grasslands are also currently suffering from under-grazing (English Nature, 2005) and are therefore
67 Rob Green, Natural England, pers. comm. 2011, cited in Kretschmer et al 2011
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threatened by relatively unrestrained scrub development. Increased management is likely to improve conditions for successional species, many of which have been declining (Forestry Commission, 2007). Therefore, the use of biomass from management practices as an energy feedstock has the potential to stimulate appropriate habitat management and improve structural diversity in woodlands. Nevertheless, care must be taken to ensure wood fuel production does not adversely impact ‘old-growth’ conditions and result in homogenisation of woodland structure with young tree growth. Potential mitigation measures As the systematic removal of agricultural residues like straw may result in the deterioration of soil fertility and lead to intensified use of grasslands which may endanger biodiversity, careful consideration of the quantities that can be extracted from the agricultural systems in question without adverse impacts is required. Ericsson and Nilsson (2006; cited in Kretschmer et al, 2012) suggest only part of the residues should be harvested for bioenergy use to avoid depletion of organic matter in the soil and thus to ensure long-term productivity. Based on a wide range of EU expertise, Elbersen et al (2012) estimate the sustainable straw harvest levels (designed to maintain the soil carbon levels in the soil) at 40% for wheat, rye, oats and barley and at 50% for rape, sunflower, rice and maize. Management practices, such as intercropping, crop rotation, double cropping and conservation tillage, can overcome some problems associated with removal of straw and other agricultural residues (EC, 2010). The replacement of straw by green manure can also help reduce the impact of the use of straw for bioenergy. Any extraction of forest residues will need to retain appropriate levels of deadwood in managed forests, ideally in all its forms and density levels, in order to cover the full spectrum of habitat conditions (Lonsdale et al, 2008 and references therein). The precise recommended density varies between sources. For instance, a minimum recommendation of 5 m3 per hectare of deadwood greater than 15 cm diameter was recommended by the Forestry Commission (2002). Kappes et al, however, (2009) recommended a target of at least 20 m3 downed CWD per hectare in managed forests to maintain litter-dwelling taxa species in European deciduous forests. Where biomass is harvested from existing semi-natural habitats, veteran trees should be retained and adequate stands of mature trees should be allowed to develop to maturity. Measures should be taken to ensure possible increases in wood fuel prices do not lead to excessive removal of biomass or the planting of exotic, fast-growing species, with negative impacts on biodiversity.
1.11.4 International biodiversity impacts and their mitigation
Potential impacts The potential for energy production from dry agriculture and forestry residues in the EU is very significant. The straw potential is well spread over practically all of the EU, the greatest potential for straw production occurring in France, Germany, Poland, Romania, Slovakia and the UK (EEA, 2006; Elbersen et al, 2012). However, the use of European or other international agricultural and forestry residues as an energy source in the UK is unlikely to be significant due to the low density of the material and relative high transportation costs compared to energy output. Therefore, it is unlikely that the UK biodiversity impacts of the use of biomass internationally will be significant.
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1.11.5 Conclusions
Summary of known impacts The potential impacts of producing energy from agricultural and forest residues are not well understood and appear to be variable depend on circumstances and the possible scale and intensity of their use (Table 21). Nevertheless, it seems likely that impacts could be positive for woodlands that are suffering from under-management. However, over extraction of wood residues could have detrimental impacts on habitat quality, e.g. through deadwood removal, as well as disturbance impacts. The use of straw and other crop residues may have relatively low impacts if carried out at sustainable levels and with mitigation measures to maintain soil health and retain food resources for birds etc. However, sustainability requirements and practices are currently uncertain. Knowledge gaps and required research More research is required on the possible impacts of the use of straw and other agricultural residues on biodiversity. There is a lack of knowledge of how biodiversity will respond to commercial scale extraction of straw from agricultural fields and woody material from forests. Investigation is required on how biodiversity response vary from the small scale of manipulative experiments (i.e. 10-ha plots) to operational regional forest management.
Table 21: Summary of potential biodiversity impacts per unit of energy produced from the use of biomass from agricultural and forestry residues for UK energy requirements
Selected technology Biomass from agricultural and forestry residues
Impacts in UK
Positive impacts Variable: no benefits for agricultural habitats, but potential to stimulate appropriate habitat management and improve structural diversity in woodlands.
Direct mortality None likely if operations are carried out appropriately.
Direct habitat loss None
Indirect habitat degradation Moderate. The extraction of straw from agricultural uses may result in loss of soil functionality, particularly where it is replaced by fertiliser, which may also increase nutrient run- off. The intensive extraction of coarse woody debris from forests would result in the loss of habitat for deadwood specialists and may have knock-on impacts for related species in the food chain.
Disturbance Low: Potential for some additional disturbance in the
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Selected technology Biomass from agricultural and forestry residues
extraction of woody biomass from forests. No impacts likely in agricultural habitats.
Secondary impacts Low: potential impacts in forests from the creation of roads/tracks.
Potential for mitigation Moderate. Extraction of only part of the agricultural residues from fields; intercropping, crop rotation, double cropping and conservation tillage can also reduce impacts. Retention of appropriate levels of deadwood in managed forests and veteran trees, ideally in all its forms and density levels.
OVERALL RESIDUAL IMPACTS LOW DETRIMENTAL
Potential for ecological Offsetting feasible through restoration / enhancement for compensation agricultural habitats and commercial forests, but only feasible for ancient semi-natural forests through protection and enhancement of degraded and/or threatened areas.
Impacts outside the UK Low due to very low imports expected
1.12 Biomass from genuinely residual wastes
1.12.1 Overview of the technology
Genuinely residual wastes comprise wastes that are not easily avoidable, such as sewage sludge, livestock residues and slurries, some food, plastic, wood and paper waste and other types of non- recyclable/compostable municipal solid waste (and similar business/commercial waste). It is important that the use of waste as a resource for energy does not compete with wider resource efficiency objectives or the waste hierarchy, which prioritises prevention, reuse and recycling/composting above energy recovery, and prioritises all of these options over ultimate disposal to landfill. Prevention, reuse and recycling should be prioritised for municipal and business waste streams in particular. Keeping this in mind, negative environmental impacts from using waste for energy can be minimised as long as pollution deriving from the storage, transport and processing of waste resources is prevented. The use of waste for energy purposes can provide environmental benefits by reducing disposal to landfill and potentially reducing the need for land-derived biomass. For many wet wastes (sewage sludge, animal slurry, food waste), anaerobic digestion is likely to be the most efficient end-use option. For dry wastes (non- recyclable/compostable municipal solid waste, waste wood), either blending with wet sources for
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anaerobic digestion or use for generation of heat and power are reasonable end uses (see Gove et al, 2010). The use of bio-waste for energy production would contribute to the more environmentally responsible management of this material. Composting produces a useful, high-quality product, but some biodegradable wastes (e.g. cooked kitchen waste and animal by-products) are not suitable for windrow composting. Such wastes can be processed through anaerobic digestion (AD), which produces biogas that can be burned to generate heat or electricity, together with digestate (a solid and liquid residue) that can be used as a soil conditioner to fertilise land. Both composting and anaerobic digestion (AD) can significantly reduce GHG emissions. A report by ERM (2006) states that AD provides higher net carbon savings than composting; 5.5 million tonnes of food waste treated by AD could generate between 477 and 761 GWh of electricity annually (this would meet the needs of up to 164,000 households) (Hogg et al, 2007). Compared to composting the same amount of food waste, treatment with AD would save between 0.22 and
0.35 million tonnes of CO2 equivalent (assuming the displaced source is gas-fired electricity generation) (ERM, 2006). Both composting and AD have a clear role in a sustainable waste policy.
1.12.2 Use in the UK
There is considerable potential for genuinely residual waste to contribute to energy production at the current time, but it must be assumed that some forms of waste will not continue at current levels due to ongoing efforts to prevent waste. It is estimated that the different forms of waste68 could contribute more than half of the total UK bioenergy potential (Howes et al, 2011). According to figures from Defra (2007), the UK produces around 100 million tonnes of waste suitable for AD each year (it should be noted that the relative contribution of manure to this total varies between studies). The UK generates an extremely large amount of food waste. WRAP69 estimates that UK households generate around 8.3 million tonnes per year of food and drink waste (equivalent to 330 kg per household per year, or just over 6 kg per household per week), and that the amount of food wasted per year is 25 per cent of that purchased (by weight). Around 5.8 million tonnes per year (70 per cent) of household food and drink waste is collected by local authorities, mainly in the residual waste stream and food-waste kerbside collections, offering some opportunity to capture the waste stream. A recent study for the European Commission70 estimates that the UK had both the highest absolute generation of food waste (8.3 million tonnes, 22 per cent of the EU-27 total) and the highest per capita generation (approximately 137 kg, compared to an EU-27 average of just below 64 kg) in 200671. It is therefore fair to assume that future prevention efforts
68 Sewage sludge, livestock manures, renewable fraction of wastes, food waste, waste wood, landfill gas.
69 WRAP, Household Food and Drink Waste in the UK, November 2009, http://www.wrap.org.uk/downloads/Household_food_and_drink_waste_in_the_UK_-_report.b5433206.8048.pdf. 70 Food waste report through DG ENV SRM FWC – full report: http://ec.europa.eu/environment/eussd/pdf/bio_foodwaste_report.pdf. 71 Calculation based on data from Food waste report through DG ENV SRM FWC – full report: http://ec.europa.eu/environment/eussd/pdf/bio_foodwaste_report.pdf and Eurostat total population data.
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could significantly reduce the availability of food waste as a bioenergy feedstock in the UK, potentially halving it just by attaining average EU food waste levels. Research by Tristram Stuart (2009) suggests that twice as much carbon savings can be made from using food waste for animal feed compared to AD (and if land use change from feeds is taken into account, it is very much more). However, this practice has largely ceased and health related regulations, particularly the EU Animal By-Products Directive, currently forbid the use of food waste for animal feed. Sewage sludge provides a constant, reliable source for bioenergy. According to Centrica72, the average person produces 30 kg of dried-out sewage sludge per year that could be used for producing biogas. This means that the UK population (62.5 m) could theoretically generate enough renewable gas to meet the annual demand of 200,000 homes, or around one per cent of the UK population. In practice, however, it is not viable to fit all 9,600 sewage treatment facilities in the UK with the necessary technology, as some only treat sewage from a very small number of people. Figures from Water UK73 suggest that around 66 per cent of the 1.6 million tonnes of sewage sludge produced annually by the water industry is treated by AD, with 60 per cent of the resultant biogas being used to generate renewable heat and power by CHP engines. The use of sewage sludge for energy production has considerable potential. Not only is it a reliable feedstock, its use for this purpose also helps to reduce the environmental impacts of this type of waste (e.g. by diverting organic waste from landfill and reducing methane emissions). The water industry has long experience of using AD to treat sewage and produce energy, and water companies already operate (and continue to invest in) related assets worth hundreds of millions of pounds. There is considerable potential for this capacity and experience to be more fully exploited, particularly if more certainty can be achieved on how to regulate mixed waste streams, and improved incentives can be provided to encourage appropriate levels of investment. According to the UK NREAP, it has been estimated that in 2009 about 6 million tonnes of waste wood were sent to landfill each year. This amount could be significantly reduced, and Defra is funding ongoing research into the most environmentally sound options for waste wood. This research, led by AEA Technology, is reported to have indicated that landfill is one of the worst options in environmental terms, resulting in methane emissions, whereas options that end in energy recovery often with a form of reuse as an interim steps are better environmentally and deliver significant carbon savings74. The best option for waste wood, however, is reuse (for example in the case of furniture) or recycling where possible. Higher value can be extracted from clean untreated waste wood for non-energy uses (such as animal bedding) and waste wood can be used in the paper/pulp industry; whereas thermal processing of contaminated wood waste poses significant risks in terms of pollutant emissions. Energy processing can be questioned as an option that provides adequate economic or environmental benefits.
72 Centrica plc, ‘Sewage project sends first ever renewable gas to grid, 5 October 2010, http://www.centrica.co.uk/index.asp?pageid=39&newsid=2080. 73 Press release: Water industry shows the way in turning waste into energy and fertiliser, Water UK, 15 July 2009, http://www.water.org.uk/home/news/press-releases/defra-anaerobic-digestion. 74 Letsrecycle.com, ‘Significant’ benefit in using waste wood as fuel, 30 November 2010, http://www.letsrecycle.com/do/ecco.py/view_item?listid=37&listcatid=5687&listitemid=56801§ion=wood.
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1.12.3 UK biodiversity impacts and their mitigation
Potential impacts The main environmental consideration to take into account when using waste for energy production is to avoid deviating from the waste hierarchy. Energy recovery from waste is low in the hierarchy (in environmental terms, it is only preferable to landfilling, with recycling/composting, reuse and prevention all environmentally preferable to energy recovery). That said, in some cases using waste products for energy production can: lead to substantial emissions savings (e.g. compared with fossil fuels); reduce the build-up of carbon debts that can accrue from other feedstocks (e.g. wood from forests, which when burned have to regrow before they can once again sequester carbon); and offer an alternative treatment method to landfill, for biodegradable waste in particular (Defra’s June 2011 Government Review of Waste Policy in England 2011 presents AD as the food waste treatment option with the greatest environmental benefit, avoiding 500 kg of
CO2 equivalent emissions compared with landfilling). Therefore, provided that waste and energy policies do not promote the burning of wastes that could be recycled/composted, reused or prevented, the potential environmental impacts of generating energy from genuinely residual wastes may in fact be rather positive. One potential negative impact, which could occur if the use of AD is rapidly expanded, is the large-scale cultivation of maize or other arable crops to co-feed AD plants together with animal slurry. Steps could be taken both through the planning system (to ensure the environmentally sound location of AD plants) and through other means (requiring AD operators report on the share of agricultural crops in their feedstock resource base) in order to limit such impacts. For certain waste streams (e.g. food waste from households), the sources of waste can be very diffuse, presenting challenges in terms of collecting enough waste to make its use for energy production both economically viable and environmentally sustainable (e.g. not resulting in excessive emissions from transporting the waste). Improved separate collection of such wastes, for example pooling of local authority resources or public procurement contracts to collect food waste from a larger number of households, and increased collection coverage could be beneficial here. However, this would also have impacts on additional transport to collect the waste, resulting in possible impacts in terms of GHG emissions, air pollution, noise, etc. The potential biodiversity impacts of generating energy from waste appear to be limited. Waste management infrastructure is generally already well-developed, meaning that in practice the on- going collection and treatment of waste should not have a noticeable impact on biodiversity. Risks could potentially arise if the use of energy-from-waste technologies develops to the extent that large new facilities need to be constructed to meet demand, but in this case existing planning and environmental regulations should help to ensure that impacts on biodiversity are minimised.
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Potential mitigation measures Efforts to support energy from waste should focus on genuine wastes and those that are hard to reuse or recycle, most notably sewage sludge, livestock manure/slurry and the portion of food waste that is genuinely unavoidable. For other types of waste, policy undoubtedly should continue to support implementation of, and movement up, the waste hierarchy. Priority should be given to the prevention of waste, followed by increased levels of re-use, recycling and composting; only when these have been attempted or are not possible should producing energy from waste become a preferred option. Safeguards could usefully be introduced, whether in waste policy (e.g. in future national waste strategies) or energy policy, to ensure that incentives are not created to motivate energy production from waste when prevention, re-use, recycling or composting are realistically achievable options. Defra’s June 2011 Government Review of Waste Policy in England 2011 highlighted the need for food waste to be collected separately at source in order to be treated by AD. On energy recovery from waste more generally, the Review states that the aim is ”to get the most energy out of waste, not to get the most waste into energy recovery”, recognising that prevention, re-use and recycling will lead to residual waste eventually becoming ”a finite and diminishing resource”, but also that projections to 2050 indicate that ”sufficient residual waste feedstock will be available through diversion from landfill to support significant growth” in energy from waste.
1.12.4 International biodiversity impacts and their mitigation
Potential impacts An EEA report on the potential for environmentally-sound bioenergy production in Europe (EEA, 2006) points out that as biowaste and residues are not generated specifically for use as an energy resource and do not serve important environmental functions, the diversion of biowaste to energy recovery options does not increase environmental pressures. It may in fact alleviate some of the environmental pressures associated with landfill and result in avoided greenhouse gas emissions. The report did however warn against the creation (unintended or otherwise) of incentives that may result in reduced efforts to prevent waste; or result in attracting portions of currently-recycled biowaste streams (e.g. paper from municipal waste and demolition wood) or streams of waste for which there is another market (e.g. food processing or agricultural residues used for animal feeds) into use as an energy resource. This could perhaps lead to increased environmental pressures as recycling of some wastes is generally more environmentally beneficial than incineration. The potential international environmental impacts resulting from UK generation of energy from genuinely residual wastes are likely to be limited, although a report by RSPB (2011) does suggest that waste imports for bioenergy generation are expected to increase as a result of an additional demand of 400,000 tonnes per year. However, the report states that the proportion of waste used as biomass in the UK is expected to decrease from 42% to 15% of total biomass for energy (mainly as a result of the substantial increase in the use of wood).
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1.12.5 Conclusions
Summary of known impacts The previous sections indicate that, provided the waste hierarchy is applied (giving preference to prevention, reuse and recycling/composting before considering energy recovery from waste), the overall environmental impacts of using genuinely residual wastes as a bioenergy feedstock may actually be positive. Beneficial environmental impacts with possible positive secondary impacts on biodiversity may include: reduced nutrient run-off to freshwater and coastal waters, emissions savings; reducing the amount of waste (especially biodegradable waste) sent to landfill, with associated reductions in methane emissions and leachate; and offering a beneficial treatment method for sewage sludge. Potential negative impacts could include: large-scale cultivation of maize or other arable crops to co-feed AD plants together with animal slurry; and challenges of collecting certain waste streams (e.g. food waste from households) that have very diffuse sources. The potential biodiversity impacts of generating energy from waste appear to be limited given that waste management infrastructure is mainly already well-developed. Risks could potentially arise if the use of energy-from-waste technologies develops to the extent that large new facilities need to be constructed to meet demand. The potential international environmental impacts resulting from UK generation of energy from genuinely residual wastes are likely to be limited. Knowledge gaps and required research Existing studies in general do not appear to offer insights into the biodiversity impacts (past or potential) of the use of genuinely residual wastes for energy generation. This could, however, be because those impacts would be minimal. More research on the future potentials for genuinely residual wastes would be beneficial; given that waste prevention, reuse and recycling efforts should reduce the future availability of wastes as a bioenergy feedstock.
Table 22: Summary of potential biodiversity impacts per unit of energy produced from the use of genuinely residual wastes for UK energy requirements
Selected technology Genuinely residual wastes
Impacts in UK
Positive impacts Low: Reduced nutrient run-off to freshwater and coastal waters.
Direct mortality None, given the nature of waste and already well- established collection methods.
Direct habitat loss None, given the nature of waste and already well- established collection methods.
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Selected technology Genuinely residual wastes
Indirect habitat degradation Uncertain: Large-scale cultivation of maize or other arable crops could occur to co-feed AD plants together with animal slurry, resulting in direct or indirect land-use change.
Disturbance Low. Unlikely unless new waste treatment/energy-from- waste facilities are developed in sensitive areas.
Secondary impacts None
Potential for mitigation High. Careful management and transportation of waste to and from energy-from waste facilities would minimise risks.
OVERALL RESIDUAL IMPACTS LOW POSITIVE
Potential for ecological Moderate, if required for indirect impacts on agricultural compensation habitats.
Impacts outside the UK Low as very unlikely to import.
1.13 Geothermal electricity
1.13.1 Overview of the technology
Geothermal electricity refers to the use of hot water or steam to generate electricity using vertical bore holes drilled deep underground to absorb the heat generated by Earth (see Figure 22). Geothermal energy, derived from the decay of radioactive materials within the earth, is stocked in the form of heat in crust rocks. Production of geothermal electricity uses Hot-Dry-Rock technology, which consists in injecting water below ground in an encased well onto geothermally heated rocks: water travels through fractures in the rock, captures its heat and then is pumped back to the surface where the captured heat is converted into electricity by a steam engine. The cooled water is injected back into the ground to heat up again in a closed loop. About 30% of the electricity produced is used to pump the water from the bottom of the well, the rest of it can be fed into the national grid.
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Figure 22: Principle of geothermal electricity generation
Source : REUK Hot-Dry-Rock technology requires drilling two boreholes in the granite, between 3 and 5 km underground, to reach temperatures of 180-190°C. Steam heated at about 185°C is brought to the surface, inside a plant covering an area of about 10,000 m²75.
1.13.2 Use in the UK
Geothermal power generation is not currently deployed in the UK and its costs are therefore highly uncertain. Nevertheless, construction of a 3 MW geothermal power plant in Cornwall began in 2009, working with a 95% capacity factor, which will supply all of the power requirements of the Eden Project and feed its electricity surplus to the grid. Planning permission has now also been granted for a 10 MW commercial-scale geothermal plant, also in Cornwall. The potential for geothermal energy in the UK is predominantly in Cornwall, where the heat flow to the surface is very high due to the decay of the radiogenic material in the South West England granite. It has been estimated that there is the capacity to produce over 35 TWh per annum (approximately 5 GW with an average load factor of 80 per cent) (DECC, 2010b), or almost 10% of the UK’s electricity demand76.
1.13.3 UK biodiversity impacts and their mitigation
The risk posed to wildlife and habitats by geothermal is considered to be very low compared to other forms of energy production. Geothermal plants have an extremely low carbon intensity and
75 Indicative figure for a 3 MW plant – Source: http://www.egs-energy.com/projects/eden-egs-plant.html 76 EGS Energy, 2011, http://www.egs-energy.com/resource/uk-and-europe.html
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sulphur emission rates that are a few per cent of fossil fuel alternatives (U.S. Energy Information Agency, 1996). Geothermal plants have relatively low land requirements compared to other energy sources (U.S. Energy Information Agency, 1996) (in the US they occupy an average of 404 m2 of land per GWh of capacity). Nevertheless, plants often are located in areas of biological importance, which requires increase mitigation planning and surveillance (Kagel et al, 2007). Binary air-cooled plants need no water, but dry steam and flash steam plants need around 20 m2 cooling water per GWh. Geothermal energy can cause subsidence, linked to geothermal reservoir pressure decline, and low level induced seismicity, which may rarely affect wildlife. The main potential impacts associated with geothermal energy result from thermal discharge into aquatic environments from wastewater, discharge to the atmosphere of hydrogen sulphide, and the contamination of wastewater with heavy and trace metals. The environmental characteristics of geothermal power are unique in a number of ways: pollutant formation may be independent of the power production rate; (ii) effluent pathways may change abruptly; (iii) preoperational testing and wild bores contribute significantly to the overall impact; and (iv) waste water may be discharged at temperatures high enough so that utilisation of the waste heat becomes both practical and imperative (Axtmann, 1975). Discharge of thermal heat through wastewater discharge can result in modification of local aquatic environments, with negative impacts for biodiversity. Discharge into the environment of water that may contain hydrogen sulphide, arsenic, boron, mercury and other trace metals (e.g. lead and cadmium). Arsenic and mercury have the potential to accumulate in sediments and organisms (Ármannsson and Kristmannsdóttir, 1992).
The mean composition of geothermal emissions is 95 per cent steam and 5 per cent CO2, H2S,
CH4, H2 and varying quantities of boron, arsenic, mercury and radon. Some localised impacts of air pollution as a result of geothermal production have been found. In a survey of the crown status of Turkey oak (Quercus cerris L.) trees in the boron-rich area Tuscany, high quantities of sulphur were found in leaves throughout the survey area, due both to the availability of this element in the geopedological substrate and to the atmospheric discharge of geothermal hydrogen sulphide. Boron and arsenic were also commonly found in the plant matrices and were associated with leaf reduction / or an increase in dry specific weight (Bussotti et al 1997). However, acute damage was found only in the area immediately adjacent to the outlets as the result of the action of boron; crown thinness was only affected by the nature of the geological substrate. A biomonitoring survey using the biodiversity of epiphytic lichens found an overall pattern of increasing biodiversity with distance from geothermal power plants suggesting that air pollution, and chiefly hydrogen sulphide from geothermal installations, is the main cause of the observed impoverishment in lichen communities. Nevertheless, a "lichen desert" was lacking, and stations classified as "altered" were found only in the surroundings of two old power plants that ceased production in 1992 and 1997, respectively, and installations for the extraction of boron salts (Bussotti et al, 2003).
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Other concerns with this technology involve noise disturbance during drilling, and risks related to drilling or fracturing (‘fracking’) the rocks (in 2006 in Basel, Switzerland, earth tremors occurred in an area where geothermal development was taking place). This was likely to be due to the unstable tectonic nature of the region), influence of natural radioactive activity occurring in the rock on the circulated water, and possible impact on local aquifers. The impacts of hydraulic fracturing on the environment are still unclear, with a major review by the U.S. Environment Protection Agency on the impact the activity may have on the environment expected by the end of 2012. The impacts of fracking for geothermal power are nevertheless expected to be considerably than from shale gas development, for which there is some anecdotal information; much of the pollution impacts associated with shale gas fracturing relate to the fracturing chemicals and transformation products used (Wood et al, 2011) which are absent in geothermal drilling. Potential mitigation measures Due to the potential risk of thermal pollution and discharge of heavy metals and hydrogen sulphide into the environment, geothermal production should avoid sites of high ecological importance. Impacts can be reduced by insulating pipes to prevent thermal losses, the fencing of power plants to prevent wildlife access, spill containment systems with potential to hold 150 per cent of the potential maximum spill. Where practical, waste heat should be re-utilised within the electricity generation process (Kagel et al, 2007). Mitigation measures of air-borne pollutants have not been widely discussed in the literature. Nevertheless, the highly localised nature of the impacts suggests the high possibility of ecological compensation in nearby areas of similar habitat type. Mitigation measures for reducing water pollution include reinjection of the wastewater into the geothermal field (Abbasi and Abbasi, 2000).
1.13.4 International biodiversity impacts and their mitigation
Potential impacts There are no plans for the importing of geothermal energy derived from outside the UK in the near future. Possible future imports of geothermal energy from Iceland are discussed in the chapter about future technologies.
1.13.5 Conclusions
Summary of known impacts The risk posed to wildlife and geothermal by geothermal is considered to be very low compared to other energy sources. Nonetheless, plants often are located in areas of biological importance, which requires increased mitigation planning and surveying, and the avoidance of locating plants in the most sensitive areas. The main potential impacts associated with geothermal energy result from thermal discharge into aquatic environments from wastewater, discharge to the atmosphere of hydrogen sulphide, and the contamination of wastewater with heavy and trace metals. Nonetheless, these impacts are considered to be very localised.
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Knowledge gaps and required research There is some research on the impacts of geothermal power generation on biodiversity, but it is difficult to make general assessments. Many of the potential impacts on biodiversity are determined by geological and local factors. The challenge is to properly determine the site- specific impacts and the long-term effects, e.g. concentrations of compounds in the steam and wastewater are highly variable and may change over time. Table 23: Summary of potential biodiversity impacts per unit of energy produced from the use of geothermal power for UK energy requirements
Selected technology Geothermal power
Impacts in UK
Positive impacts None
Direct mortality Low: There could be some very localised impacts on vegetation as a result of hydrogen sulphide emissions. Discharge of small amounts of arsenic and mercury may impact reproduction.
Direct habitat loss Low: Power plants and roads have small land surface requirements and only result in minor losses of habitats.
Indirect habitat degradation None
Disturbance Low: Possibility of increased disturbance as a consequence of new roads.
Secondary impacts None
Potential for mitigation Moderate: the siting of plants and associated infrastructure (eg roads and power lines) may be constrained, but pollutant impacts may be reduced through capture and appropriate disposal.
OVERALL RESIDUAL IMPACTS LOW
Potential for ecological Variable depending on the impacts habitats. compensation
Impacts outside the UK Low: See chapter on future energies.
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1.14 Tidal stream
1.14.1 Overview of the technology
Tidal stream is the horizontal flow of water through the oceans, caused by the continuous ebb and flood of the tide. Unlike water currents, which are continuous, unidirectional and form a steady horizontal movement of water flowing down a river or stream, a tidal stream (or tidal current) changes its speed, direction and horizontal movement regularly according to the forces of the tide controlling it. Tidal stream generation is the extraction of kinetic energy from those currents generated by the tides using submarine energy converters, which can be visualised as underwater wind turbines (Figure 23). The technology involved is very similar to wind energy: the blades convert a fraction of the kinetic energy into electrical energy and send it back to shore through a submarine cable.
Figure 23 - Tidal stream project illustration - ©www.tidalstream.co.uk Driven by patterns caused by the movement of the earth and the moon, tidal streams are highly predictable compared with some other forms of renewable energy. With a capacity factor of around 40%, it can therefore be a reliable renewable energy source where the flow rate is between 2 and 2.5 m/s (i.e. fast enough for energy generation to occur at satisfactory levels, but not so fast that the structure is exposed to heavy structural loads that may cause damage). Installation and maintenance, however, are costly.
1.14.2 Use in the UK
There is currently only one operational 1.2 MW tidal stream turbine in Strangford Narrows, in Northern Ireland. A number of tidal stream and wave energy devices, ranging up to 1 MW, have been deployed at the European Marine Energy Centre (EMEC) in Orkney (Scotland) for testing.
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Developers are currently evaluating a number of specific projects (at least 30 suitable tidal streams locations have been identified77) but these are unlikely to be operational and making a significant contribution before 202078 given the high costs and lead times for construction.
Commercial deployment of tidal stream has yet to begin but prospective scenarios suggest up to 300 MW (approximately 0.9 TWh per year) could be deployed in the UK by 202079. Much larger scale deployment is anticipated in the period beyond 2020.
Figure 24 - Average flow for a Spring/Neap Tide - Source: Atlas of Marine UK Renewable Energy Resources Indeed, as shown in Figure 24, the tidal streams of the British seas represent a potentially large asset (estimated at 18 TWh per year80), and the country is at the forefront of the development of this technology, thanks to a number of companies with significant marine design and engineering experience, representing a sizable share of device developers and patents. In its policy effort to encourage progress from the demonstration to the commercial phase, the Department of Energy and Climate Change now offers 5 ROCs (Renewable Obligation Certificate) per MWh produced through tidal stream technology.
77 BERR, Tidal Power – Current UK Use, http://www.berr.gov.uk/energy/sources/renewables/explained/wave- tidal/tidal/current-use/page17055.html 78 DECC 2011 UK Renewable Energy Roadmap, p58 http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/renewable-energy/2167-uk-renewable-energy- roadmap.pdf 79 Ibid, p58 80 Black and Veatch, 2004, ‘Tidal Stream Energy – Resource and Technology Summary Report’, p4, http://www.carbontrust.co.uk/SiteCollectionDocuments/Various/Emerging%20technologies/Technology%20Directory /Marine/Other%20topics/TidalStreamResourceandTechnologySummaryReport.pdf
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1.14.3 UK Environmental Impacts
Potential impacts Tidal stream is still an emerging technology and therefore there have been limited direct observations from which to judge the nature and scale of the impacts. The literature refers to information on the impacts of other human activities in marine environments for insights into the likely impacts of tidal stream development, coupled with information on the vulnerabilities of habitats and species and ecosystem processes. The environmental issues are similar to those of other Marine Renewable Energy Infrastructures (MREIs), such as offshore wind and wave power, including negative impacts (direct habitat loss, collision impacts, and disturbance/displacement) and positive impacts (artificial reef creation and the Marine Protected Areas effect). These are considered separately below. Direct habitat loss All tidal stream devices require some contact with the seabed in the form of either moorings or the device itself, as well as electrical cables connecting the installation to the shore. Modification of, or damage to seabed habitats is therefore inevitable, particularly in the case of more substantial structures. However, the scale of the impact is likely to depend on the location of the installation, and the direct impacts may be insignificant for marine conservation if sensitive areas such as high conservation value biogenic reef structures including Horse Mussel (Modiolus modiolus) are avoided (Inger et al, 2009). The hard structures will create habitat in the form of artificial reefs, but these will be different habitats to those lost. The greatest impacts are expected during construction. Decommissioning is expected to be relatively uncomplicated and should leave the seabed in a similar condition to what it had before the project (Fraenkel, 2006). Collision impacts Very little is currently known about the potential for collisions between marine wildlife and tidal stream installations or other MREIs (Bell and Side, 2011; Inger et al, 2009; Wilson et al, 2007). Wilson et al (2007) therefore reviewed existing evidence from other marine activities to identify general factors affecting MREI collision risks for marine mammals, fish and seabirds This revealed that: “Collision risks are not well understood for any marine vertebrates. Of the three animal groups considered here, fish are best understood and diving birds least. Man-made collision risks are more diverse and common than generally supposed. The rate of whale–ship strikes is a significant example. Underwater collision risks typically become well studied after they have become a conservation concern. Animals may appear to behave illogically when faced with novel situations. Subtleties of gear design (shape, colour etc) as well as environmental conditions (turbidity, flow rate etc) can markedly change collision rates. Objects in the water column will naturally attract fish and their predators. Stationary objects in flowing water can herd fish upstream until they become exhausted limiting their behavioural options.
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The proximity and relative orientation to other objects will impact escape options and the combined collision risk while topography will impact escape options and animal approach angles. Collision risk will vary with age of organisms, with juveniles likely to be more at risk than adults because of reduced abilities or experience. The potential for animals to escape collisions with marine renewable devices will depend on their body size, social behaviour (especially schooling), foraging tactics, curiosity, habitat use, underwater agility and sensory capabilities. A variety of warning devices and gear adaptations have been developed for marine mammals and fish (although not as yet birds) in recognition of underwater collision issues.”
From this Wilson et al, suggest that cables, chains, power lines and components that move freely on the surface probably pose a greater risk of collision than fixed submerged structures (2007). Rotating turbines, such as those used for tidal stream devices, have the potential to seriously injure and kill organisms, with particular concern related to cetaceans, seals and diving sea birds. But tidal stream turbines rotate relatively slowly (in Strangford Lough typical speed is 15 rpm; the maximum rotor blade tip velocity is 10–12 m/s), and are therefore unlikely to be a serious threat to wildlife. Wilson et al also assessed the likely collision risks for marine mammals, fish and birds with MREIs in Scotland, according to seven parameters: depth, time of day, season, turbidity, flow characteristics, location and topography. They conclude that almost all species of fish are at some risk, and rank all groups as being of ‘moderate collision concern’ other than bottom dwelling species (flatfish), which are of ‘low collision concern’. However, bottom-dwelling fish will be at greater risk from devices that have moving parts in close proximity to the seabed, such as some proposed vertical axis turbines. Pelagic fish that migrate diurnally - moving to near the seafloor during the day and moving to the surface at night - will be at risk from both seabed and surface structures. The probability of collision with MREIs is highly influenced by the size of the animal concerned, and therefore all marine mammals were considered to be of ‘high collision concern’, except for large toothed whales (i.e. odontocetes), such as Sperm Whale (Physeter macrocephalus), Northern Bottlenose Whale (Hyperoodon ampullatus) and a variety of beaked whales, Mesoplodon spp), which are rankled as being of ‘low collision concern’ (as they primarily occur in deep water). Collision risks to birds greatly depend on the extent to which species are likely to be distributed through the water column. Wilson et al therefore consider that Northern Gannets are of ‘moderate/high collision concern’, divers, grebes, seaduck, terns and auks are of ‘moderate collision concern’, and shearwaters are of ‘low/moderate collision concern’. All other seabirds are of ‘low collision concern’. A more recent assessment by Furness et al (2012) also identified auks and divers, as well as European Shag and Great Cormorant, as the species most vulnerable to adverse effects from tidal turbines in Scottish waters. Due to the lack of information on the actual risk to organisms of collision with tidal stream installations, Scotrenewables are reported to be deploying collision detection hydrophones and
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cameras on a prototype device which will detect collision events and allow subsequent examination of the results by video (Bell and Side, 2011). Disturbance Only limited disturbance is expected from the installation of tidal stream devices. Pile driving has not been used to date; nevertheless, noise generated during the construction of tidal devices from vessel and installation activity can have localised impacts (reported to be between 165-175 dB re 1μPa at 1m (rms)) (OSPAR Commission, 2009). Although it is unlikely that sound levels from the normal operation of tidal stream (and wave) devices will exceed those of vessels and other activities (Bell and Side, 2011), significantly more research is required on the chronic long-term effects of MREI on marine organisms. Fish populations, crustacean spawning grounds and other components of marine ecosystems have the potential to be affected by changes in local currents, water flow, turbidity and sedimentation patterns, and by any associated changes in the benthos. Fish populations may be affected at different life-history stages, with subtle effects on spawning, feeding and migration (Bell and Side 2011). It is possible that changes to the flow regime on either side of the tidal stream array may shift sediment plumes, but the impact is expected to be on a small scale, particularly in comparison with tidal range schemes (Fraenkel, 2006). Additional research needs to be undertaken to determine how operations could change local currents. Indirect impacts The generation of power from tidal currents (and waves) intercepts the hydrokinetic energy that would otherwise have been expended elsewhere in the natural environment, and the interruption of this dynamic will inevitably have consequences for other physical and ecological processes. The scale and nature of these impacts depends on the amount of energy generated, rather than the technology (Bell and Side, 2011). Tidal energy extraction can affect sedimentary processes at two scales: firstly, localised effects may result in scour and associated deposition of re-suspended sediment elsewhere; secondly, there may be more dispersed impacts in seabed topography, littoral zone limits and sediment transport rates, with regional implications for erosion and deposition (Michel et al, 2007). The possible impact of disruptions to hydrodynamic processes on the transport of larvae and other propagules of marine organisms is currently under-researched. The timing and location of release of larvae, for example, is often finely tuned to provide favourable feeding conditions and transport to favourable settling grounds. A change to this process could have significant implications for trophic linkages within the ecosystem. Research in this area in relation to marine renewable energy is urgently needed (Bell and Side, 2011). Secondary impacts In common with other marine energy technologies, most tidal stream generation schemes will require some new electricity transmission and transformation infrastructure, including submarine cables, high-voltage power lines from the coast inland and grid transformer stations (see section 1.18 for further discussion). Transmission entry capacity constraints in the north of England and Scotland are still preventing the connection of new generation projects, awaiting the
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development of the planned high-voltage Beauly–Denny power line. If tidal stream installations are located in otherwise undeveloped coastal areas, this electricity infrastructure could have an impact on coastal and onshore biodiversity. Artificial reef The increased hard substrate surface area provided by infrastructural developments in coastal environments has been shown to attract many marine organisms. These artificial reefs can benefit fisheries, rehabilitate habitat, or offer an attraction for diving ecotourism (Jensen, 2002). The shape and size of installation components, particularly the structural diversity, determine the extent to which they attract wildlife, and the nature of the species that colonise the surfaces (Peterson and Malm, 2006). The design of components can be modified to promote indigenous species rather than more competitive non-native or invasive species. Whilst artificial reefs are likely to stimulate some species, others may be negatively impacted, for example structures on sand seabeds may result in increased species diversity (Inger et al 2009), but could affect other adjacent benthic communities through greater predation (Langlois et al, 2005). Marine Protected Area effects Tidal stream and other MRE installations are likely to act as de facto marine protected areas (MPAs) because the risk of collision and gear entanglement for fishing boats will prevent fishing in the immediate area. In addition, larger arrays of tidal stream and wave installations are likely to have enforced exclusion zones preventing the entry of trawlers and other marine vessels, reducing damage to seabed habitats from bottom-towed fishing gear. However, MREIs may not necessarily be located in areas that bring benefits for conservation, restoration or fisheries management, although exclusion zones that were sited with no intention to protect biodiversity have been shown to protect fish stocks (Friedlander et al, 2007). Potential mitigation Impacts on marine mammals and birdlife can be minimized through the appropriate siting of tidal stream technology. Adequate spatial distribution of turbines will help minimize fish and marine mammal fatalities. Fences and sonar sensors could also be used to keep wildlife away from rotors. In the Strangford Lough development, a sonar has been installed to detect the presence of marine mammals, and this has resulted in the shut-down of the tidal stream device on a number of occasions (Bell and Side, 2011). There is scope for deliberate enhancement of habitat around marine renewable energy developments, e.g. to provide substrates suitable for juvenile lobsters, and for fish stock enhancement through the release of hatchery-reared individuals into suitable areas.
1.14.4 International environmental impacts
No import of tidal stream energy to the UK is expected and therefore the impacts are not considered here.
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1.14.5 Conclusions
The impacts of tidal stream are highly uncertain due to the lack of commercially operating schemes. The main concerns around tidal stream installation focus on the potential for collision risk with marine mammals, fish and seabirds, although the exact risks are unknown. Habitat loss is expected to be low and mitigated by the addition of hard substrate which can act as an artificial reef with potential biodiversity benefits. The design of installations can be modified to improve their impacts on biodiversity. In larger arrays, the impact of trawling exclusion is expected to have a positive benefit for fisheries and habitat rehabilitation. However, the impacts of the removal of hydrokinetic energy from the marine ecosystem are less well understood. The biggest concern is the possible impact on the transportation of larvae and the potentially severe consequences for trophic linkages within the marine ecosystem. Table 24: Summary of potential biodiversity impacts per unit of energy produced from tidal stream energy production in the UK
Selected technology Tidal stream
Impacts in UK
Positive impacts Uncertain: Possible creation of de facto marine protected areas, particularly in larger arrays, with potential benefits for fisheries. Artificial reef creation could increase species diversity and abundance.
Direct mortality Low/moderate: Collision risks for seabirds are expected to be mostly low, but risks for fish and particularly marine mammals may be higher.
Direct habitat loss Low (although dependent on design) but some habitats may be of very high biodiversity importance.
Indirect habitat degradation Uncertain: Possible impacts of altered tidal currents (flow, sediment movement, turbidity, etc.), and likely interference with transportation of larvae.
Disturbance Low: Some noise disturbance, primarily during construction but also operation.
Secondary impacts Uncertain: Impacts associated with the transmission and distribution of energy, depending on how much new infrastructure is needed and whether the coastal area is otherwise undeveloped.
Potential for mitigation Moderate: Appropriate siting is of most importance. In addition a variety of warning devices and gear adaptations
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have been developed for marine mammals and fish (although not as yet birds) in recognition of underwater collision issues.
OVERALL RESIDUAL IMPACTS UNCERTAIN
Potential for ecological Uncertain, but benthic damage could possibly be offset compensation through protection of other important areas (eg from bottom trawling).
Impacts outside the UK None expected.
Knowledge gaps and required research There is a need for further research on the physical and ecological impacts of energy extraction from tidal currents by tidal stream technologies, e.g. how operations could change local currents that could negatively affect crustacean spawning grounds. In particular, there is a need to better understand how the transport of larvae and other propagules of marine organisms are affected. This could have significant implications for trophic linkages within the ecosystem. Site specific models are also required, which take into consideration the local impacts of energy extraction (Bell and Side, 2011). There is a lack of information on the actual risk to animals of collision with tidal stream installations.
1.15 Tidal range
1.15.1 Overview of the technology
Tidal range is the vertical difference between high and low tide. The power that can be captured from water flowing from high to low is proportional to the squared range or head. The number of sites presenting ranges high enough to enable commercial use is very limited worldwide (it is calculated that a 7 m head is required for economical operation81) though with huge potential, as some facilities have rated capacities of several gigawatts. Tidal range energy can be harnessed through dams similar to those used for traditional hydroelectric power. Tidal range installations include tidal barrages, which stretch from one side of an estuary to the other, and tidal lagoons, where the dam creates a self-contained enclosure that does not stretch across the estuary.
81 Ocean Energy Council, 2012- http://www.oceanenergycouncil.com/index.php/Tidal-Energy/Tidal-Energy.html
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Figure 25: Principle of tidal range harnessing - Source: ©Green Rhino Energy Both tidal barrages and lagoons utilise the same method of electricity generation. While the tide is rising, the reservoir behind the dam is filled with water through open sluices. The gate to the turbine is closed. When high tide is reached, the sluices are shut. Once sea level has receded to sufficiently low levels, the turbine gate is opened and the water from the reservoir channelled onto the turbine. This process is labelled ‘ebb generation’. A less efficient alternative to ebb generation is flood generation in which water flows through the turbine into the reservoir, generating electricity during reservoir flooding. Tidal lagoons can be built in pairs, which can supply continuous power when operating at different times. In addition, these may provide a very large energy storage device by the pumping of water from one lagoon into the other when there is over-supply of electricity. During periods of high electricity demand, the pumped water can be released into the lower lagoon through turbines in order to generate electricity. Tidal lagoons require shallow water and a large tidal range, limiting the number of potential sites where tidal lagoons can be built. Two large tidal lagoons under consideration in the UK each encompassed an enclosing area of 400 km2 (Keder and McIntyre Galt, 2009). To date, most of the world tidal range generation occurs at La Rance tidal barrage in Northern France, with a 240 MW (peak) generation dam harnessing 13 m tides. Smaller schemes also exist in Canada, Russia and China.
1.15.2 Use in the UK
No tidal range barrage is currently being operated in the UK. Sites with the highest tidal ranges offering potential for development are located around the Severn, Dee, Solway and Humber estuaries (Figure 7-2), the total potential resource for the UK amounting to an estimated 40 TWh per year82.
82 Committee on Climate Change 2011, The Renewable Energy Review
http://hmccc.s3.amazonaws.com/Renewables%20Review/The%20renewable%20energy%20review_Printout.pdf
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Figure 26: Average Tidal Spring (left) & Neap (right) Range - Source: Atlas of Marine UK Renewable Energy Resources
In 2010, the UK Government published the findings of a feasibility study into Severn tidal power, which considered five different schemes, including three barrages and two lagoons. Of the schemes investigated, the Cardiff-Weston barrage was the largest and despite its high capital costs (approximately £34 billion), this was considered to offer the best value for money. However, the Government concluded at the time that there was not a strategic case for public investment in tidal energy schemes and no further plans were made to implement the scheme. Now it appears that private financing for this scheme may be available but only if some governmental support is also provided via the proposed Contracts for Difference mechanism. This is a mechanism that aims to support investment in low-carbon electricity generation by stabilising revenues for generators at a fixed price. Consequently, a Commons Select Committee is now investigating the potential for the proposed Cardiff-Weston B to deliver low-carbon electricity to the UK, the likely cost to consumers and the potential impacts on wildlife and local employment83.
1.15.3 UK environmental impacts
Potential impacts Tidal range schemes can have wide ranging impacts on biodiversity, many of which are expected to be highly location dependent. As the number of commercial scale installations of tidal range schemes is limited, the findings of this section are primarily based on the findings of the review into the Severn Estuary Barrage, which included an assessment of the potential and the impacts of tidal range installations in the UK, and the experiences of La Rance tidal barrage in France.
83 http://www.parliament.uk/business/committees/committees-a-z/commons-select/energy-and-climate-change- committee/inquiries/parliament-2010/a-severn-barrage/
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Nevertheless, inadequate baseline data at La Rance make it difficult to gauge the barrage’s impact on biodiversity (SDC, 2007). The very large size of the proposed barrage in the Severn (e.g. up to 520 km2 of the estuary impounded, compared with the 17 km2 at La Rance) limit the potential for extrapolation of environmental data from previous projects. Habitat loss and degradation Estuaries host a very wide variety of intertidal, subtidal and transitional habitats. Intertidal habitats, which encompass the largest area of most estuaries, include intertidal mudflats and sandflats, saltmarshes and rocky features. While the UK holds a significant proportion of Europe’s tidal potential estuarine resource, its estuaries and other wetlands are of considerable value for biodiversity, including areas of international importance for migrant and overwintering waterbirds and for migratory species of fish (SDC, 2007). The greatest impact of tidal range schemes biodiversity is as a consequence of the degradation and loss of habitat, especially intertidal mudflats and salt-marshes. Intertidal mud and sandflats are dominated by large numbers of a small number of species, such as polycheate worms, amphipod crustaceans and gastropod molluscs, which in turn support a large number of bird species. Reducing the tidal range will significantly diminish the intertidal area available to these species. Analysis of several potential barrage schemes in the Severn Estuary found that under the smaller scheme between 3,400 – 5,500 ha (or 70 – 76%) of upstream intertidal habitats would be lost while 5,800 – 14,4000 ha (or 59 – 76%) would be lost in the largest scheme (SDC, 2007). There will be changes to the nature of sediments and (possibly) the degree of consolidation and physical properties of the sediments. This will have implications for the distribution of invertebrates in the mudflats, and consequently the species they support (Black & Veatch, 2007). The construction of a barrage is likely to result in a change to sedimentation patterns, with an increase of fine silty material deposited upstream of the barrage, with increased scouring and erosion around the outflow of the turbines, which could change the associated species assemblages (Frid et al, 2011). Nevertheless, the area of habitat degraded is not proportional to the area affected by reductions in tidal range as it will depend on the quality of the areas affected and the subsequent changes to sedimentary regime. This is highly estuary specific and therefore difficult to predict. Salt marshes act as important nurseries for juvenile fish and numerous invertebrates. Changes to the tidal, current and sediment regimes may erode salt marsh communities beyond the point of resilience (Burd, 1992; cited in Keder and McGalt, 2010). Reductions in tidal range will result in less frequent inundation of the saltmarsh zone. As a consequence, upper salt marshes, which are most under threat in the UK, may be permanently exposed and susceptible to invasion by terrestrial vegetation (Black & Veatch, 2007). Rocky intertidal zones could similarly experience changes to inundation periods, sedimentation and wave action resulting in changes to species assemblages. Transitional habitats are those that exist between fully marine and terrestrial conditions and include: grazing marsh, reedbeds, saltings, wetlands, grasslands and woodlands. These are likely to be impacted during the construction phase, subsequent economic developments and through changes to the flooding regime. Less frequent inundation may be expected to alter species composition while an increase in the water table, in principle, may improve the freshwater habitats (Mitchell et al 1981; cited in Black and Veatch 2007), although the actual conditions are
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likely to be highly dependent on local characteristics. Of more immediate concern is damage to these habitats during construction of the installation and the likelihood of secondary economic development in the surrounding areas (see below). The above changes, in particular to intertidal habitat, represent a threat to waterbird populations in affected areas (Clark (2006) cited in Tucker et al (2008)) by reducing the habitat and time available for feeding. Nonetheless, it is difficult to assess the impacts of these changes on the species populations in the estuary. Some birds may be able to utilise neighbouring habitat if it is below carrying capacity, but this may result in increased competition between individuals. Evidence of such an impact comes from the Cardiff Bay amenity barrage, where, following habitat loss, displaced birds that moved to the Severn estuary were unable to maintain body condition leading to a 44% increase in mortality rate (Burton et al, 2010). Fish may also be substantially impacted by habitat loss. Sand banks and saltmarshes are also areas of great importance to the health of fish populations, as the banks are important nursery and feeding grounds for many fish species (Wolf et al, 2009) and changes in the nature of the habitats will alter their suitability as nursery or spawning areas for fish (Frid et al, 2011). There is debate whether reduced turbidity and more stable conditions upstream of a barrage could result in an increase in species abundance (ie productivity) and species diversity, which might compensate for loss of habitat. Indeed, predictions of barrage intertidal invertebrate associations indicate a likely increase in abundance and biomass of species and associations characteristic of less dynamic estuaries (Warwick et al, 1989). In particular, there may be an increase in taxa such as Cyathura, Scrobicularia, Cerastoderma, Mya and Hediste diversicolor and a decrease in species associated with hypertidal estuaries such as Hydrobia, Macoma and Bathyporeia. In addition, reduced turbidity could result in a higher biomass of suspension feeders. It is also anticipated that there would be a shift in the size distribution of certain species, notably Nephtys hombergii, Macoma and Hydrobia towards larger individuals (Black & Veatch, 2007). This form of increased productivity has been observed in La Rance where an increase in the estuary’s carrying capacity for invertebrates and higher organisms has been reported (Kirby, 2006; cited in Black & Veatch, 2007), notwithstanding the loss of one third of the intertidal area. Nevertheless, these assertions remain controversial and in the absence of a greater understanding of the local conditions, it appears to be more appropriate to assume that losses of existing feeding habitat will not be compensated for by increases in food availability. Collision risk The passage of fish through turbines of tidal range schemes has the potential to significantly impact on fish populations (see Wolf et al, 2009). Estuaries are important to migratory fish returning to fresh water systems to spawn, including Salmon (Salar salar), Twaite Shad (Alosa fallax), Allis Shad (Alosa Alosa), Sea Lamprey (Lampetra fluviatilis) and River Lamprey (Petromyzon marinus), Eel and Sea Trout. The SDC notes that there can be significant fish mortality as a consequence of passage through turbines with projected injury rates for adult Salmon of 40%, Eel (28%) and juvenile Shad (53%) of a Cardiff-Western Severn Barrage. Studies on fish populations from existing tidal schemes are inconclusive and it is appears that design features are particularly important in reducing mortality. For example, studies at the Annapolis–Royal power plant (Nova Scotia) have shown that fishways were ineffective at
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reducing marine life mortality. Studies at La Rance in France, show that while the installation impacted on the migration of certain species (particularly trout) (SAGE, 2004; cited in Black&Veatch, 2007), the overall impacts on migratory species can be described as minimal (Shaw, undated). Factors causing fish mortality fall into two main categories: (a) hydraulic conditions of pressure change, cavitation, shearing and turbulence, producing direct, characteristic injuries; (b) conditions influencing the likelihood of actual fish collision with turbine components, such as rotation speed and diameter of passes. These factors can be enhanced or reduced by alterations in turbine operation and, possibly, design (Davies, 1988); although fish size is also a factor with larger fish being more vulnerable (Charlier, 2003). Disturbance A large potential for disturbance exists during construction and decommissioning phases, such as noise from pile driving and other construction activities. Potentially greater disturbance is expected for tidal lagoons than barrages that intersect with a greater area of intertidal habitat (Burton et al, 2010). But disturbance is likely to be low during operation, unless barrages are used as a basis for roads and railways. Indirect effects Large tidal schemes have the potential to affect tidal levels and thus lead to further loss of intertidal habitat at other protected area sites (Burrows et al, 2009; cited in Burton et al, 2010). In additional, transitional habitats may be affected by changes in land use as a result of secondary economic developments related to the construction of the barrage (see SDC, 2007). Potential mitigation measures It may be possible to design barrages in a manner to minimise impacts on intertidal areas. Wolf et al (2009) suggest larger installed turbine capacity used in dual mode operation can retain a large percentage of the present tidal range within the basin area. By modifying water levels with appropriate time intervals, managers can chose to favour intertidal or subtidal communities according to their respective ecological interests for avifauna and flatfishes, local socio- economical preoccupations or recreational activities carried out in the basin (Desroy and Retière, 2004). The siting of a barrage higher up an estuary, so as not to block access to important rivers for migratory fish, may be possible in some cases. Many of the major impacts associated with construction, can be mitigated by careful planning, for example, mitigating the impact of noise from pile driving, by avoiding critical times of year for marine mammals and fish (Frid et al, 2011).
1.15.4 International environmental impacts
No import to the UK of energy from tidal range is expected and therefore the impacts are not considered here.
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1.15.5 Conclusions
The absence of large-scale operational tidal range power schemes makes it difficult to adequately assess the likely ecological implications, and therefore most of the analysis is based on the detailed review of the Severn barrage. However, the Severn is a very large, unique and extreme estuarine environment and therefore not typical of other possible tidal power sites in the UK. The individual circumstances of each location will be crucially important in determining potential impacts. Therefore, it is difficult to draw conclusions on the likely impacts of the use of tidal range energy that are applicable to all suitable sites in the UK. Nonetheless, it is clear that any feasible tidal range scheme would result in the change and loss of large areas of intertidal habitat, including important foraging areas for waterbirds. Potentially significant fish mortality due to collision with turbines would also be likely if adequate precautionary measures are not taken. Furthermore, the potential sites for tidal range schemes are located in estuaries that are of high biodiversity value, especially for their internationally important populations of water birds, as well as their migratory fish and their unique hydrological and ecological conditions. These sites are therefore largely protected by national and European level designations. Options to mitigate the impacts of the schemes are limited and compensation for residual impacts is virtually impossible given the size and types of habitat involved. It therefore seems inevitable that any significant use of tidal range energy in the UK would result in significant unavoidable residual biodiversity impacts.
Table 25: Summary of potential biodiversity impacts per unit of energy produced from the use of tidal range energy in the UK
Selected technology Tidal range
Impacts in UK
Positive impacts Uncertain: Potential for increased productivity and species richness due to reduced turbidity and more stable conditions although this is not proven at scale.
Direct mortality High for migratory fish species, as a consequence of collision with turbines
Direct habitat loss High: Large reduction in intertidal habitats (e.g. up to 75% in the Severn), loss of upper zones of saltmarsh due to reduced inundation, possible loss of transitional habitats.
Indirect habitat degradation Moderate: Potential loss of transitional habitats during construction. Large tidal schemes may affect tidal levels leading to further loss of intertidal habitat at other protected area sites
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Disturbance Variable: Noise and visual disturbance affecting marine mammals and birds during construction, but low disturbance during operation unless used a basis for railways and/or roads.
Secondary impacts Variable: May stimulate further development, especially if combined with new transport.
Potential for mitigation Low: Habitat loss remains large. Measures could be taken to increase fish passage through turbines or to discourage fish from migrating towards turbines.
OVERALL RESIDUAL IMPACTS HIGHLY DETRIMENTAL
Potential for ecological Low, as very difficult to recreate large areas of estuarine compensation habitat
Impacts outside the UK No imports expected.
Knowledge gaps and required research There are many uncertainties regarding the possible impacts of tidal barrages and lagoons, and therefore more research is required to: determine the precise impacts of the reduction of high tide levels associated with ebb generation, and the impacts associated with reservoir flooding generation. Ebb generation is likely to deprive upstream riverbeds of sediment, with flooding generation would probably result in increased rates of sedimentation downstream. This is in turn is likely to impact habitats in salt marshes (Keder & McIntyre Galt, 2009). establish whether increased productivity will compensate adequately for the loss of habitat and reduced feeding times in cases of greater loss of intertidal area. ascertain whether more stable conditions are likely to increase species richness and biomass without adversely affecting existing species assemblages. It is also important to note that any tidal range scheme would require detailed site-specific analysis and modelling of the likely implications for biodiversity as a result of changes to the tidal, hydrological and sedimentation regimes.
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1.16 Wave power
1.16.1 Overview of the technology
Wave energy harnesses the vertical movement of the surface water by placing devices on the surface of the oceans (on the shoreline or in deep waters) that capture this periodic up-and-down motion and converts it into electrical power. Most devices fall into three main groups: Oscillating water columns (OWC), where the motion of the waves forces air out of a column through a turbine (see Figure 27).
Figure 27 - Principle of oscillating water column - Source: http://www.energystockblog.com Buoyant moored devices move with the waves relative to an anchored structure below sea level. The floating structure’s motion, relative to the anchored structure, is used to drive electromechanical or hydraulic energy converters.
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Figure 28 – Two examples of buoyant moored devices: the Duck (©1996 Ramage) and a point absorber (Source: EPRI 200784) Hinged contour devices, where segments move relative to each other in the waves. Their relative motion, concentrated at the joints between the segments, is used to pressurize a hydraulic piston that drives fluids through a motor, which turns the coupled generator (see Figure 8-3). The Pelamis P1 generator tested in Orkney (Scotland) at the European Marine Energy Centre (EMEC), used in a 2.5 MW wave farm in Aguçadoura (Portugal), is an illustration of the potential of this technology.
Figure 29 - Principle of the edge contour - Source: EPRI 200785 Regardless of the type of device, wave harnessing technology involves equipment that needs to be very resistant, since at sea the devices are exposed to potentially harsh conditions (severe storms, algae, corrosion, etc.). Connection to the grid is similar to that of offshore wind farms: medium-voltage buried cables bring the current to an onshore connection point.
84 http://oceanenergy.epri.com/attachments/ocean/reports/EWTEC_Bedard_Sep_11.pdf
85 Ibid.
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Potential environmental considerations for the development of wave energy include visual and noise impacts (which are device-specific, with considerable variation) and toxic releases from leaks or accidental spills of liquids used in systems working with hydraulic fluids.
1.16.2 Use in the UK
Wave technology is still at a development and testing phase, and few power devices are installed to date. These include: the LIMPET (Land Installed Marine Powered Energy Transformer), a 500 kW shoreline oscillating water column installed on the Hebridean island of Islay (Western Scotland). It has been connected to the national grid since 2000. the Pelamis P2, the new generation sea-snake, a 750 kW rated hinged contour device with a capacity factor86 of 25-40%, is being tested at the European Marine Energy Centre in Orkney (Scotland). It is the first deepwater grid-connected wave energy converter. the Wave Hub site, installed 16 km off the Northeast coast of Cornwall in Southwest England, provides offshore infrastructure for the demonstration of new wave energy generation devices. The 12- tonne hub is linked to the national grid via a 25 km subsea cable operating at 11 kV. The infrastructure can demonstrate arrays up to a total of 20 MW, with potential extension to 50 MW. The greatest wave energy potential in the UK is located on the west coast of the British Isles, with the areas of highest potential density being off Cornwall, Pembrokeshire and the Outer Hebrides. The practical offshore wave energy resource is estimated to be 50-90 TWh per year, or 14-26% of current UK demand87. Though there is no firm planning for wave technologies development, there are signs that a wider deployment is being prepared: several Strategic Environmental Assessments (SEAs) have been produced, hinting at an opening of the UK waters for potential deployment. Following the SEA of Scottish waters, the Crown Estate awarded commercial leases in the Pentland Firth and Orkney Waters for 1.6 GW of marine generation (wave and tidal stream)88. The technology is therefore expected to have a limited role in the period to 2020, but may significantly contribute to the UK energy mix by 2030.
86 See definition p. 10
87 Pelamis Wave Power 2012 Global Resource, http://www.pelamiswave.com/global-resource
88 DECC 2011, UK Renewable Energy Roadmap, p. 61.
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1.16.3 UK biodiversity impacts
Potential impacts As wave energy converters have yet to be commercially deployed, there have been limited direct observations with which to judge the nature and scale of their impacts. Therefore assessments often consider information from the study of other human activities, including other Marine Renewable Energy Infrastructure (MREI)(eg those relating to tidal stream power discussed in section 1.14), which provide insights into the likely impacts, coupled with information regarding the vulnerabilities of habitats and species and physical processes. The adverse impacts associated with wave energy are considered to be less severe than those associated with tidal barrages, for instance, although the impact is spread out over a greater surface area (Wilhelmsson et al, 2010). Impacts are associated with the different phases of project implementation; some of the most significant of which relate to the construction phase of the project, such as from visual and noise disturbance, but some of impacts are likely to be short- lived. Direct habitat loss Wave energy convertors are unlikely to cause substantial widespread alteration to benthic habitats, as they generally float on the water surface or are suspended within the water column (Mueller and Wallace, 2008). While anchoring to the seabed will inevitably result in localised habitat loss, it is only expected to have significant implications for marine conservation through inappropriate placement of devices in sensitive areas, such as fish spawning habitats or areas of high species diversity (Witt et al, 2012). In particular, inshore lobster habitats are likely to overlap strongly with areas of greatest wave potential, requiring particularly careful planning to avoid adverse impacts (Bell et al, 2010; cited in Bell and Side, 2011). Furness et al (2012) point out that although the actual surface area of wave devices may be trivial in terms of its coverage of coastal marine habitats they may in practice exclude some seabirds from much larger areas of habitat. This is because at the sea surface, some wave devices (e.g., Pelamis, Sea Dragon) may take up significant areas that may affect surface dwellers in terms of a physical barrier (Boehlert and Gill, 2010). Thus some seabirds may avoid such devices, for example because of their constraints on birds’ ability to land and take off in between such structures. Collision impacts These impacts are not currently well understood and require innovative means of detecting and recording collision/entanglement events. Strike risk between wave devices and mobile marine species will depend on the device design, while avoidance ability will be a function of species and body size, diel activity patterns, or age and reproductive structure (Witt et al, 2012). The greatest risk with respect to wave power installations is the presence of cables, coils and power lines that are relatively mobile and more complex to navigate (Witt et al, 2012). In addition, there is a potential greater collision risk associated with diving birds, in particular with respect to the likelihood of the installations acting as fish aggregating devices (see below) (Grecian et al, 2010). However, Furness et al (2012) consider that such risks are likely to relatively compared to other risk to diving birds such as from tidal stream devices and fishing nets.
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Disturbance The impact of noise as a result of human activities is being increasingly recognised to have an adverse effect on marine environments, including marine mammals, fish and benthic invertebrates (Witt et al, 2012). For MREIs, the most significant impacts are likely to be during construction, in particular in the use pile driving or drilling for installing anchoring devices (Bell and Side, 2011). For wave installations, where pile driving is unlikely to be necessary, the impacts during construction are thought to be less acute (Witt et al, 2012). Very little information is available on the chronic impacts resulting from the operation of wave installations that will depend on the energy emitted, frequency of noise and the auditory ranges of species. Current research on the noise impacts of the operation of wind farms on selected fish species suggests there is little impact on marine species other than avoidance (Anderson et al, 2007). Indirect effects Bell and Side (2011) and Shields et al (2011) review the ecological implications of alterations to the hydrodynamics of marine environments as a consequence of extracting wave and tidal energy. Reductions in wave energy are most likely to be important at or near the shoreline within the littoral and shallow sublittoral where in natural circumstances much of the accumulated energy of a wave field is expended. Thus, modification of wave dynamics is likely to affect patterns of coastal erosion, sediment deposition and sediment transport, as well, perhaps, as local mixing. However, as there is a paucity of physical evidence on the subject it is difficult to makes generalisations across locations (Michel et al. 2007). Physical changes in mixing, and turbidity etc may have ecological effects. For instance, sediment disturbance may generate phytoplankton blooms through the release of extra nutrients, while localised reductions in light attenuation due to turbidity may decrease productivity (see Witt et al, 2012; for a discussion by the authors, although no further primary sources are cited). Wave power arrays will potentially have a higher concentration of cables than wind farms producing electromagnetic fields detectable by a range of marine organisms such as bony fish, elasmobranchs, marine mammals and marine turtles (Witt et al, 2012). Certain wave devices that employ coil and magnet engineering could generate greater electromagnetic fields than those emanating from cables. There is a considerable lack of information on the impacts of electromagnetic fields on marine organisms (see Witt et al, 2012 and references cited within). Artificial reef Studies related to the foundations of physical structures in the marine environment indicate that such surfaces are rapidly colonized by epifauna, fish and crustaceans, resulting in the diversification of species over time (Wilhelmsson et al, 2010). The presence of wave energy devices on the water surface will also serve to attract juvenile and adult fish. Wave energy installations, particularly oscillating devices, are likely to be deployed in species-poor sandy sedimentary habitats which could result in increased species diversity (Inger et al 2009), but could affect other adjacent benthic communities through greater predation (Langlois et al, 2005). Fish aggregating devices (FADs) Floating surfaces and objects in marine environments tend to attract many species of fish that aggregate below them (Inger et al, 2009). This is likely to be particularly relevant to wave power
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devices that have larger floating surface areas. Understanding of why this happens is limited, and the implications for fisheries management requires more research. Nonetheless, FADs act to concentrate fish populations rather than boost recruitment and therefore there is a clear possibility for over-exploitation. It may also increase the collision and entanglement risks for larger predatory birds, fish and marine mammals that feed on concentrated prey resources (Grecian et al, 2010). On the other hand, as noted Furness et al (2012) consider that the risk of collisions and entanglement with wave devices is likely to be generally low for seabirds, and therefore there could be small benefits from increases in fish density for some seabirds (provided they do not avoid such structures). This benefit could be further increased if the devices provide suitable roosting platforms. Marine Protected Area effects Effective marine protected areas are created as the possibility of collision and gear entanglement means that areas in the immediate vicinity will be not fished by types of commercial fishing. It is not yet clear what size areas are likely to be effected by the installation of wave power devices but larger arrays will clearly have a greater positive cumulative effect. Potential mitigation Mitigation of negative impacts of wave technology should focus on the appropriate siting to avoid sensitive areas such as important breeding or foraging areas and migratory routes. Particular attention will need to be paid to the design of cables and coils to reduce risk of entanglement and minimise complexity of navigation around such structures. The design of substrate surfaces should act to increase the artificial reef effect and promote indigenous species, but care must be taken to ensure that it does not result in increased predation in neighbouring habitats.
1.16.4 International impacts
No import of wave power energy to the UK is expected and therefore the impacts are not considered here.
1.16.5 Conclusions
The overall biodiversity and environmental impacts of wave power devices are poorly understood and therefore most of the discussion in the literature is based on inference from other technologies. Nevertheless, it is expected that the impacts are likely to be lower than other MREIs in particular with respect to habitat loss and disturbance. However, some areas with high biodiversity value habitats could be affected. Other concerns relate to the risk of collisions with the devices and associated cables, etc. The severity of such risks for marine mammals is uncertain, but for birds it is likely to be low compared to tidal stream technologies and other hazards such as fishing nets. The habitat and shelter created by the devices and the prevention of trawling within the vicinity could help to locally increase invertebrate and fish populations, and help benthic habits recover from damage caused by fishing gear. This could benefit other species, including diving birds
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provided that they are not vulnerable to collisions or are likely to keep well away from wave structures. Overall it seems unlikely that wave devices will have major biodiversity impacts provided they avoid sensitive sites. For example, Furness et al (2012) consider that of 38 assessed birds species no species are highly vulnerable to wave devices, only three species are moderately vulnerable: Red-throated Diver (Gavia stellata), Black-throated Diver (Gavia artica) and Great Northern Diver (Gavia immer); the remaining species having low or very low vulnerability. Furthermore, for some other taxa, such as some fish and benthic fauna positive impacts might outweigh negative impacts. Table 26: Summary of potential biodiversity impacts per unit of energy produced from the use of wave power derived energy in the UK
Selected technology Wave power
Impacts in UK
Positive impacts Uncertain: Possible benefits from new habitat (artificial reefs), fish aggregation and trawling exclusion from the vicinity of arrays.
Direct mortality Uncertain: Likely to be low collision or entanglement risks for birds, but risks for marine mammals are uncertain and potentially higher.
Direct habitat loss Low: Minimal loss of benthic habitat, but some sensitive habitats could be impacted.
Indirect habitat degradation Uncertain: Interference with waves and currents could change high energy marine ecosystems, resulting in impacts on phytoplankton, and knock-effects on food webs; but potential impacts are poorly understood.
Disturbance Low: Noise during construction expected but low and short temporal scale.
Secondary impacts Uncertain: Stimulation of economic development and marine technologies could lead to further developments, eg aquaculture, harvesting of marine algae.
Potential for mitigation Moderate: Avoidance of sensitive areas, but further research is required to identify wave device design mitigation measures.
OVERALL RESIDUAL IMPACT UNCERTAIN
Potential for ecological Uncertain: Benthic damage could possibly be offset through
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Selected technology Wave power compensation protection of other important areas (eg from bottom trawling).
Impacts outside the UK None. No imports expected.
Knowledge gaps and required research However, it is clear that further research is required into the impacts of wave technologies on biodiversity, especially in relation to marine mammals. In particular, further studies are required on impacts related to: noise and other forms of disturbance resulting from the operation of wave installations, for example in relation to the energy emitted, frequency of noise and the auditory ranges of species. impacts of electromagnetic fields on marine organisms. ecosystem disruption from changes in wave energy and turbidity etc. implications fish aggregating device effects for fisheries management and wider biodiversity. the potential cumulative impacts of large arrays.
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1.17 Future technologies
1.17.1 Overview of the technologies
The UK Government is open to the option of buying renewable energy from other countries in the case where these produce an excess of renewable energy credits before 2020. However, the UK’s ability to import renewable energy from abroad depends on the installation of new high voltage undersea power cables from the continent, and from Iceland and Norway. The importation of renewable electricity from the Mediterranean and North African regions also depends on the development of the European Smart Grid. It is therefore unlikely that the UK will import large quantities of electricity until 2025 or later. Renewable technologies that the UK could import electricity from in the future include Concentrating Solar Power (CSP) from southern Spain and northern Africa; large-scale photovoltaic solar power in continental Europe; volcanic geothermal energy from Iceland; and hydropower in Norway. As this imported renewable energy capacity is most likely to have been driven by international collaboration or by domestic policies in the producing country, rather than from a direct consequence of the demand from the UK, it can be assumed that the impacts of the infrastructure are not attributable to the UK. Energy imports can be regarded as having an indirect positive impact on the UK by reducing the need for domestic energy infrastructure. The UK’s use of this energy may also reduce the need for new storage capacity in the producing country. The most significant impacts on UK biodiversity as a consequence of these imports are likely to come from the installation of power cables on the sea floor. The impact of the necessary transmission and storage infrastructure is considered in section 1.18.
1.17.2 Description of the technologies and their impacts/mitigation
Concentrated Solar Power (CSP) Concentrated solar power systems are currently being developed in southern Spain, and have a large potential for development in northern Africa and the Middle East (EASAC, 2011). Solar radiation is projected onto a black surface or fluid-filled tube by means of large arrays of mirrors that track the movement of the sun over the course of the day. The heated black surface reaches sufficient temperatures to convert the encased fluid (oil, steam, salt, or gas) into a more energetic form that powers a turbine and generates electricity. Some of the technologies are capable of storing energy for a few hours, but a cheap safe heat storage system has not yet been developed. Current plants rely on large quantities of fresh or salt water for cooling; air cooled systems are being developed but they are less efficient and more expensive. Large-scale CSP
technologies are expected to have GHG emissions of about 9–55 g CO2-eq/kWh. CSP converts the full spectrum of light and is therefore efficient and low cost, and favours the development of large-scale power plants. Nevertheless, the construction of a sufficiently large
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number of these plants to supply Europe, and the transmission lines to connect northern Africa to northern Europe will take both time and large amounts of investment. In 2011, 850 MW of CSP were operating in Spain, and a further 876 MW were under construction in Spain, Morocco, Algeria and Egypt. The Desertec Foundation, which is developing a solar thermal plant in Tunisia, expects the Tunur 2 GW plant and a 600 km high voltage direct current power cable line to Italy to be complete by 2016. The Mediterranean Solar Plan89 aims to develop 20 GW of renewable electricity capacity by 2020 on the south and east shores of the Mediterranean, as well as the necessary infrastructures for the electricity interconnection with Europe. Potential impacts on biodiversity Large-scale CSP plants are likely to be constructed in arid areas where solar irradiation is highest and land is cheap. The direct land use of plants is expected to be relatively small, e.g. 11 or 17 m2/MWh (EASAC, 2010); however, arid habitats are very sensitive to disturbance and the introduction of invasive alien species. Massive establishment of solar plants in an area may affect animal or plant populations by cutting dispersion routes and fragmenting populations. CSP plants currently need large quantities of water for cooling, and smaller quantities for cleaning the mirrors. In arid areas, this means the water demand could have substantial indirect biodiversity impacts through the loss of groundwater and/or the impacts of displacing irrigated agriculture to other areas. The water used for mirror cleaning supplies 10 to 20 mm/year to the soil below the mirrors, which will stimulate plant growth and attract wildlife on a small scale. Birds and bats might be killed through collision with top mirrors, tower and buildings, or by heat shock or burning damage in the concentrated light beams. Insects may be attracted to the mirror surfaces as they mistake them for water. This could result in fatality or reproduction failure for insects that lay eggs in water. Mitigation potential The risk of direct mortalities through collision is greatly reduced by appropriate design, e.g. illumination, colour and reflectiveness (EASAC, 2010). The development of air cooled plants would avoid the use of fresh water. Large-scale photovoltaic solar power Today’s commercial solar cells have an efficiency of less than 20%, and current large scale PV arrays therefore need large areas of land or roof area, e.g. 550 to 2250 m2/MWh in Germany (EASAC, 2010)90. Lower feed-in tariffs will limit the construction of large-scale PV in northern Europe; however, technology breakthroughs may mean large-scale PV arrays become commercially viable by 2025 (Keder and MacIntyre Galt, 2009). Potential impacts on biodiversity Roof-top systems will have little impact on biodiversity as long as they do not affect bat roosts or other building features important for particular urban bird. Ground-based systems will occupy relatively large areas of land, but this is currently mostly biodiversity poor agricultural land. If this
89 http://ec.europa.eu/europeaid/what/energy/policies/southern-neighbourhood/msp_en.htm
90 http://www.pv-magazine.com/news/details/beitrag/germany--fit-cuts-pushed-back-2-large-scale-pv-projects- announced_100006008/#axzz21Sx1JWMJ
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land continues to be grazed or mown underneath the solar array, this should preserve most species present. Secondary infrastructure will result in some local habitat loss. Volcanic geothermal energy Iceland91 has a large potential to produce electricity from volcanic geothermal energy, using steam turbines, and already generates around 600 MW. Hydropower and pumped storage in Norway Norway has 29 GW hydropower generation capacity that produces 120 TWh per annum. This covers almost all of its own electricity demand92. Norway is looking to offer a significant volume of storage capacity for renewable energy in Europe by using surplus electricity to pump water back into hydropower plants, and then release it to generate electricity when needed93. Norway could supply storage capacity for continental renewables now through Norway’s existing high voltage DC cable to the Netherlands, and by 2018 through the commissioned high-voltage link with Järpströmmen in Sweden, and a planned cable with Germany (NORD.LINK). Norway could supply storage capacity for the UK’s offshore wind by 2020 through the planned UK-Norway connection94. Potential impacts on biodiversity Norwegian hydropower has proven negative impacts on the local environment as well as on biodiversity95. Pumped storage also has the potential for substantial negative impacts on the environment and biodiversity of rivers due to the abrupt changes in river flow levels. Mitigation potential A certain level of pumped storage capacity that causes only minor disturbances for river ecology should be possible in Norway, but will require careful environmental planning and control to maintain minimum river flows and avoid flood surges.
1.17.3 Conclusions
Summary of known impacts None of these technologies will provide renewable energy for the UK until around 2020, because of the need for new high voltage direct current cable connections. The most significant impacts of these energy imports on biodiversity around the UK are likely to come from the installation of these power cables in the North Sea and English Channel (see section 1.18 for discussion). A large-scale expansion of pumped storage in Norway’s hydropower system could potentially have
91http://www.renewableenergyfocus.com/view/25097/uk-ministers-eye-iceland-s-volcano-powered-electricity/
92 http://www.renewablepowernews.com/archives/1409
93 http://www.thelocal.de/money/20120621-43307.html
94 http://www.northseagrid.info/project-description
95http://2012.technoport.no/?abstract=the-dual-environmental-challenge-global-concerns-in-a-local-environment-an- analysis-of-three-norwegian-hydropower-cases
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significant negative impacts on biodiversity, if it is not carefully managed and restricted. The expansion of geothermal energy in Iceland and large-scale PV energy in Europe is much less likely to have negative consequences for biodiversity provided it is not located on highly biodiverse sites. The potential impacts of large-scale Concentrating Solar Power in northern Africa are difficult to predict at this stage in the technology development. The impacts will depend particularly on whether it will be feasible to significantly reduce freshwater use. Research gaps The impact of increased pumped storage capacity on Norway’s river ecosystems. The relative environmental impacts of different technology options for Concentrating Solar Power in northern Africa.
1.18 Energy grid – transmission and storage
1.18.1 Overview of the technology
Large-scale use of renewable energy in the UK and Europe by 2020 will depend on the development of an electricity network that functions as a Smart Grid – i.e. an interactive, two- way, intelligent electricity distribution network that continuously balances a huge variety of decentralised supply, demand and storage points. The UK’s ability to import renewable energy from abroad also depends on the installation of new high voltage undersea power cables. Developing these connections is likely to take a decade or more. It also depends on the development of a Smart Grid across Europe. In 2010, the EC proposed a network of energy super highways across the EU as part of an “energy blueprint” (COM (2010) 677 final). The expanded grid would carry renewable energy from the periphery of the Union to major consumption areas in continental Europe. The system would also offer further connection opportunities for offshore RES (Fichaux and Wilkes, 2009). A large diversity of renewable generation across the EU would increase security of energy supply, helping to compensate for periods of below average generation in some areas. The next EU budget (the Multiannual Financial Framework for 2014- 2020) has allocated EUR 200 billion worth of funding for the implementation of grids for electricity, oil and gas, as part of the “Connecting Europe Facility” (COM 2011_17).
1.18.2 Description of the technologies and their impacts/mitigation
Long-distance underwater power cables The UK’s ability to import and export renewable energy depends on the installation of new high voltage direct current (HVDC) undersea power cables across the English Channel, the North Sea, the Irish Sea, and the Mediterranean.
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Continental Europe: The UK is currently connected to the continent via two interconnectors to the Netherlands and France. There are plans to connect with Belgium, the tidal-rich Channel Island of Alderney and a new nuclear power station in France96. Ireland and Scotland: The East-West Interconnector HVDC cable connection with Ireland is due to open later in 2012. It will have a total length of 261 km, of which 186 km is submarine cable and 75 km is subsoil cable. An additional cable project is being commissioned for 2019. The ISLES project funded by the EU’s INTERREG IVA OP, has proposed the following areas for an offshore interconnected transmission network and subsea electricity grid off the coast of western Scotland and in the Irish Sea/North Channel area.
Figure: Proposed Area for Offshore Grid Source: www.islesproject.eu Norway: A HVDC cable connection is being proposed for completion by 202097. Iceland: The proposed UK-Iceland connection would require a 1,000-1,500 km HVDC cable98 under the North Sea. North Africa: At present, Europe is connected to northern Africa only by two 400 kW AC undersea cables between Morocco and Spain. If Europe is to import 15% or more of its electricity demand from northern Africa and the Middle East, this would need at least 20 5 GW DC power lines under the Mediterranean (EASAC, 2011). Potential impacts on biodiversity The laying of new marine pipelines will induce fragmentation, habitat loss or degradation, mortality or damage and disturbance to fauna, including impacts on fish spawning areas or nursery grounds. Digging in buried pipelines will cause some fauna mortality (e.g. benthic species), habitat loss or degradation, higher noise, increased suspended sediment, etc. These impacts will also occur if the cable is removed on decommissioning. The impact of the construction of the UK-Ireland submarine cable on subsurface sediments was assessed as being
96 http://www.renewableenergyfocus.com/view/25097/uk-ministers-eye-iceland-s-volcano-powered-electricity/
97 http://www.northseagrid.info/project-description
98 http://www.renewableenergyfocus.com/view/25097/uk-ministers-eye-iceland-s-volcano-powered-electricity/
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slight (AECOM & Metoc, 2009). Marine transmission cables that are laid onto the seabed have the potential to disrupt sedimentation flows, with increased turbidity reducing the availability of light, thus impacting primary food production (Wilhelmsson et al., 2010). Increased sedimentation rates may also clog fish gills and obscure underwater visibility, thereby disrupting predator-prey interactions (Balata et al, 2007). The cables produce electromagnetic fields detectable by a range of marine organisms such as bony fish, elasmobranchs, marine mammals and marine turtles (Witt et al, 2012). There is a considerable lack of information on the impacts of electromagnetic fields on marine organisms, though they are known to affect eels Anguilus anguilus (see Witt et al, 2012 and references cited within). The UK-Ireland interconnector was anticipated to produce an electromagnetic field detectably higher than the earth’s magnetic field within 50 m of the cable, but the induced electric field strength will be well below those which have been found to cause avoidance behaviour in elasmobranchs (100 μV /m) (AECOM & Metoc, 2009). Power cables use substantial amounts of copper (800 tonnes of copper per km99), resulting in indirect impacts on biodiversity from copper mining. Mitigation potential Benthic and intertidal habitats of high conservation interest, such as horse mussel Modiolus modiolus habitat or aggregations of Sabellaria spinulosa, should be avoided if possible. The electro-magnetic field can be reduced if two cables are laid in the same trench, as their magnetic fields will cancel each other out (AECOM & Metoc, 2009). High voltage power lines, Smart Grid and storage capacity in the UK The expansion of low carbon technologies, particularly from micro-generation, is going to depend on the development of the UK’s Smart Grid by 2020 (AEA, 2010). In addition, the development of new large-scale renewables, particularly offshore and onshore wind, will need the construction and upgrading of high voltage power lines across the UK. The Smart Grid will require new hardware and software instruments, and some new infrastructure, in particular a comprehensive and much more efficient network of two-way electricity connections and a larger and more decentralised storage capacity. Potential impacts on biodiversity and mitigation potential New high-voltage power lines can result in habitat loss or damage during construction or site access, habitat fragmentation (creation of barriers, fragmentation of habitats, sites or corridors, subdivision of animal territories), change in hydrology (water flows) of wetland habitats, loss of species during construction or maintenance, hazards to birds or bats through collision and/or electrocution with power lines100. The area underneath power lines needs to be regularly cleared of vegetation, which can result in habitat loss and fragmentation, but can also provide increased habitat diversity, for example edge habitats within woodland.
99 http://www.theengineer.co.uk/home/blog/icelands-volcanoes-could-power-the-uk-but-at-what-cost/1012334.article
100 http://www.eirgrid.com/media/EirGrid%20Ecology%20single%20pages%20-%20online%20- %2011th%20June%202012%28r%29.pdf
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1.18.3 Conclusions
Overall the impacts are expected to be low. Some disturbance will occur during construction and lines could result in changes to sedimentation flows. Impacts from overhead electric lines are known on birds and could be important, but research on the impacts at population level is scarce (BIOIS et al., 2012). Table 27: Summary of potential biodiversity impacts per unit of energy produced from energy transmission and storage in the UK
Energy transmission and storage Potential impacts
Impacts in UK
Positive impacts None.
Direct mortality Low. Minor impacts during construction. Some bird fatalities due to electrocution or collision with electricity transmission cables / power lines.
Direct habitat loss Low: if benthic habitats of high conservation interest are avoided.
Indirect habitat degradation Low. Surface-laid cables may affect sediment flows, which could affect seabed habitats. Energy storage using large water reservoirs, have similar impacts as hydroelectric power.
Disturbance Low. Minor noise, sediment suspension, and other disturbance during construction.
Secondary impacts None
Potential for mitigation High: Most habitats can be restored following pipeline construction, most sensitive habitats can be avoided.
OVERALL RESIDUAL IMPACTS LOW DETRIMENTAL
Potential for ecological High for pipeline impacts on most terrestrial habitats if compensation fragile habitats and that require long-time scales for restoration are avoided.
Impacts outside the UK Similar to the UK - as above.
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Annex A - List of operating fossil-fuel burning power stations in the UK
Station Name Fuel Installed Year of Location capacity commissioning (MW)
Aberdare District Energy gas 10 2002 Wales
Aberthaw B coal 1 586 1971 Wales
Aberthaw GT gas oil 51 1971 Wales
Arnish diesel 10 2001 Scotland
Baglan Bay gas turbine 510 2002 Wales
Ballylumford B gas/oil/OCGT 656 1968 Northern Ireland
Barkantine Heat & Power Company Gas CHP 1 2000 London
Barra diesel 2 1990 Scotland
Bowmore diesel 6 1946 Scotland
Bridgewater District Energy gas 10 2000 South West
Burghfield gas/oil 47 1998 South East
Charterhouse St, London gas/gas oil CHP 31 1995 London
Chickerell gas/oil 45 1998 South West
Chippenham gas 10 2002 South West
Cockenzie coal 1 152 1967 Scotland
Cottam coal 2 008 1969 East Midlands
Cowes gas oil 140 1982 South East
Derwent gas CHP 228 1994 East Midlands
Didcot A coal/gas 1 958 1972 South East
Didcot GT gas oil 100 1972 South East
Drax coal 3 870 1974 Yorkshire and the Humber
Drax GT gas oil 75 1971 Yorkshire and the
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Station Name Fuel Installed Year of Location capacity commissioning (MW)
Humber
Eggborough coal 1 960 1967 Yorkshire and the Humber
Fawley oil 968 1969 South East
Fawley GT gas oil 68 1969 South East
Fellside CHP gas CHP 180 1995 North West
Ferrybridge C coal/biomass 1960 1966 Yorkshire and
Ferrybridge GT gas oil 34 1966 Yorkshire and
Fiddler’s Ferry coal/biomass 1961 1971 North West
Fiddler’s Ferry GT gas oil 34 1969 North West
Fife Power Station gas 123 2000 Scotland
Five Oaks light oil 9 1995 South East
Grain oil 1 300 1979 South East
Grain GT gas oil 55 1978 South East
Immingham CHP gas CHP 1 240 2004 Yorkshire and the Humber
Indian Queens gas 140 1996 South West oil/kerosene
Ironbridge coal 940 1970 West Midlands
Keadby gas/oil 749 1994 Yorkshire and
Kilroot coal/oil 662 1981 Northern Ireland
Kingsnorth coal/oil 1 940 1970 South East
Kingsnorth GT gas oil 34 1967 South East
Kirkwall diesel 16 1953 Scotland
Knapton gas 40 1994 Yorkshire and the Humber
Lerwick diesel 67 1953 Scotland
Little Barford GT gas oil 17 2006 East
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Station Name Fuel Installed Year of Location capacity commissioning (MW)
Littlebrook D oil 1 370 1982 South East
Littlebrook GT gas oil 105 1982 South East
Loch Carnan, South Uist diesel 10 1971 Scotland
London Heat & Power Company gas CHP 9 2000 London (Imperial College)
Longannet coal 2 304 1970 Scotland
Marchwood gas 842 2009 South West
Peterhead gas/oil 1180 1980 Scotland
Pilkington - Greengate gas 10 1998 North West
Ratcliffe coal 1 960 1968 East Midlands
Ratcliffe GT gas oil 34 1966 East Midlands
Rugeley coal 1 006 1972 West Midlands
Rugeley GT gas oil 50 1972 West Midlands
Sevington District Energy gas 10 2000 South East
Shotton gas CHP 45 2001 Wales
Slough coal/biomass/ 61 1918 South East
Solutia District Energy gas 10 2000 Wales
Stornoway diesel 19 1950 Scotland
Taylor's Lane GT gas oil 132 1979 London
Thames Valley Power Gas/Gas oil CHP 15 1995 London
Thatcham light oil 10 1994 South East
Tilbury B coal 1 063 1968 East
Tilbury GT gas oil 68 1968 East
Tiree diesel 3 1945 Scotland
Uskmouth coal/biomass 363 2000 Wales
West Burton coal 2 012 1967 East Midlands
West Burton GT gas oil 40 1967 East Midlands
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Station Name Fuel Installed Year of Location capacity commissioning (MW)
Wilton GT2 Gas 42 2005 North East
Wilton Power Station Gas/Coal/Oil 280 1952 North East Source: DECC, 2011
164 Towards integration of low carbon energy and biodiversity policies | Annex A
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29 March 2013
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