Why Biomass? 1.4 Wood Is a Renewable Fuel; Its Production and Use Is Almost Carbon Neutral
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R OYAL ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION C OMMISSION ON E Biomass NVIRONMENTAL as a P Renewable OLLUTION Energy Source Biomass as a Renewable Energy Source Energy Renewable a as Biomass About the Royal Commission on Environmental Pollution The Royal Commission on Environmental Pollution is an independent standing body established in 1970 to provide authoritative advice on environmental issues. Its terms of reference are: To advise on matters, both national and international, concerning the pollution of the environment; on the adequacy of research in this field; and the future possibilities of danger to the environment. Within this remit the Commission is free to consider and advise on any matter it chooses; the UK government or the devolved administrations may also ask it to consider particular topics. The primary function of the Commission is to contribute to policy development in the longer term by providing a factual basis for policy-making and debate, and setting new agendas and priorities. It considers the economic, ethical and social aspect of issues alongside the scientific and technological aspects. It sees its role as reviewing and anticipating trends and developments, identifying fields where insufficient attention is being given to environmental problems, and recommending actions that should be taken. The Commission has published 24 reports, and many of their recommendations have been accepted and implemented by successive governments. The members of the Commission have a wide range of expertise and experience in natural and social sciences, medicine, engineering, law, economics, and business. They serve part- time and as individuals, not as representatives of organisations or professions. A full-time Secretariat supports The Chairman and Members by arranging and recording meetings and visits; gathering and analysing information; handling finances and administration; and drafting and publishing the Commission’s reports. In the course of its studies, the Commission canvasses a wide range of views. Information on its work (including minutes of meetings, background papers by consultants and summaries of evidence submitted) is available via www.rcep.org.uk. BIOMASS AS A RENEWABLE ENERGY SOURCE A Limited Report by The Royal Commission on Environmental Pollution Contents Page CHAPTER 1 – Introduction 3 CHAPTER 2 – Biomass fuels 9 Energy crops 9 Forestry products 21 Sawmill co-products 24 Municipal arisings 26 Conclusions 28 CHAPTER 3 – Generation using biomass fuels 30 General principles 30 Heat generation 31 Combined heat and power 33 Electricity generation 40 Environmental implications 43 CHAPTER 4 – Meeting the target 47 Economics of biomass 47 Transport 52 Energy conversion facilities 58 Land-take 60 Planning for biomass 63 Phased delivery 67 A strategic approach 68 CHAPTER 5 – Conclusions and recommendations 69 APPENDIX A – Policies to support biomass – description of current 72 schemes APPENDIX B – Case studies 75 APPENDIX C – Scope and limitations of the special report 83 APPENDIX D – Conduct of the report 85 APPENDIX E – Members of the Commission 88 APPENDIX F – Reports by the Royal Commission on Environmental 89 Pollution REFERENCES 90 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE 1 2 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE CHAPTER 1 – INTRODUCTION Context 1.1 Energy consumption throughout the world, but particularly in industrialised societies, has been steadily increasing. Much of the energy consumed, 97% in the case of the UK1, comes from non-renewable sources. The present use of carbon-based non-renewable energy is unsustainable, inter alia because of the effect of the resultant carbon dioxide (CO2) emissions on the global climate. Reduction in demand must be part of the solution2 but alternative energy sources must also be developed. All energy sources come with environmental penalties, whether from the construction of dams and barriers or from the impact of renewable sources such as wind on rural landscapes, but these impacts must be balanced against the necessity of developing low-carbon sources that are both economically viable and also secure. 1.2 The Royal Commission’s Twenty-second Report, Energy - The Changing Climate published in 2000, advocated a number of steps that the government should take, both in terms of domestic policy and through international negotiation. A key recommendation was that a long-term target should be set to reduce CO2 emissions by 60% by 2050. This was based on the contention that the maximum concentration of CO2 in the atmosphere should not exceed twice the pre-industrial level. The government subsequently accepted that the UK 3 should put itself on a path towards this aim . In order to reach a 60% reduction of CO2 emissions, it is vital for the government to concentrate on encouraging low- or non-carbon electrical and heat generation. As a component of a renewable energy generation mixture, biomass should play an important role. 1.3 There are three types of indigenous biomass fuel: forestry materials, where the fuel is a by- product of other forestry activities; energy crops, such as short rotation coppice (SRC) willow or miscanthus, where the crop is grown specifically for energy generation purposes; and agricultural residues, such as straw or chicken litter. Biomass can also be imported, mainly in the form of pelleted sawdust (which is already an internationally traded commodity). Why Biomass? 1.4 Wood is a renewable fuel; its production and use is almost carbon neutral. Trees absorb CO2 to photosynthesise organic compounds using solar energy. The energy is stored chemically and released when the wood is subsequently destroyed - whether by natural decay or combustion. Hence, although CO2 is released into the atmosphere when wood is burnt, an equivalent amount of CO2 has been taken from the atmosphere during growth. Some net release of CO2 would take place if the growing, processing or transporting of the wood involved the use of fossil fuel. 1.5 The carbon in biomass used as fuel does not therefore contribute to greenhouse gas emissions. Technically emissions from biomass use are reported in the UK greenhouse gas ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE 3 inventory as a memo item, but are not included in the national total. This is in accordance with international guidelines from the Intergovernmental Panel on Climate Change (IPCC) and the United Nations Framework Convention on Climate Change (UNFCCC). On the other hand emissions of nitrous oxide and methane from the combustion process are included in the national total (because the carbon is balanced by photosynthetic uptake but the methane and nitrous oxide are not). Emissions of nitrous oxide from any fertiliser used to grow the biomass are also included, as are emissions of CO2 from fossil fuel used in forest or field operations and transportation. 1.6 Unlike most other renewable energy sources biomass can be stored and used on demand to give controllable energy. It is therefore free from the problem of intermittency, which is a problem for wind power in particular. Also, unlike most other renewable sources, biomass offers potential as a source of heat as well as electricity, offering high conversion efficiencies. This potential appears to have been overlooked in government policies to promote biomass, which have concentrated on electricity generation. In this report we therefore concentrate on biomass as a fuel for heat or combined heat and power (CHP) . We will show that biomass energy offers an opportunity to rethink energy generation and to drive a step-change in the efficiency of power and heat production. The implications for the UK’s CO2 reduction targets are highly significant. 1.7 Biomass energy technology is inherently flexible. The variety of technological options available means that it can be applied at a small, localised scale primarily for heat, or it can be used in much larger base-load power generation capacity whilst also producing heat. Biomass generation can thus be tailored to rural or urban environments, and utilised in domestic, commercial or industrial applications. Box 1A Units of energy production Rates of production of energy are measured in watts (or kilowatts (kW), megawatts (MW) or gigawatts (GW)). If a production rate of one watt is maintained for one hour, the amount of energy produced is one watt-hour. This report uses watts and the units derived from watts to indicate energy generally. Where it is important to distinguish heat (thermal energy) from power (electrical energy) a suffix (th or e, respectively) is used. For example a CHP facility with a total output of 40 MW might typically produce 30 MWth and 10 MWe. 1.8 The technology is most efficient where a source of fuel and a demand for heat are within an economically viable distance of each other. In this report we examine the costs of transporting biomass fuels, both financially and in terms of CO2 emissions. We show that we might expect a significant proportion of the UK to be able to meet the maximum distance criterion for efficient use of biomass. In some areas of the UK fuels could be grown as energy crops and in others it would arise as a by-product of agriculture, forestry and other activities. 1.9 Biomass offers important opportunities for UK agriculture and the countryside. As the North Sea resources become exhausted, the shift from coal to oil and gas-fuelled generation 4 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE means that most of our fuels will come from outside the UK. This dependence on international sources for our fuel reduces security of supply and marginalises the domestic agricultural sector. Biomass energy provides an opportunity to develop a fuel source from the UK’s own resources, increasing the security of its energy supply; it also offers new opportunities for UK agriculture. Why not biomass? 1.10 Biomass has been successfully used as a source of energy across Europe but it has not become established in the UK; there are several reasons for this.