Chapter 6 Renewable sources of energy Key points Progress against the Renewable Energy Directive (RED) target In 2016, 8.9 per cent of total energy consumption came from renewable sources; up from 8.2 per cent in 2015. Renewable electricity represented 24.6 per cent of total generation; renewable heat 6.2 per cent of overall heat; and renewables in transport, 4.5 per cent. The UK has now exceeded its third interim target; averaged over 2015 and 2016, renewables achieved 8.5 per cent against its target of 7.5 per cent Trends in generation Electricity generation (table 6.4) in the UK from renewable sources fell marginally by 0.2 per cent between 2015 and 2016, to 83.2 TWh. Lower rainfall and wind speeds resulted in lower hydro and wind generation, more than offsetting a 16 per cent increase in total capacity, to 35.7 GW in 2016 (table 6.4). For the second year running, solar photovoltaics were the leading technology in capacity terms at 11.9 GW, representing a third of total electricity capacity. This resulted in a 38 per cent increase in generation (table 6.4). Onshore wind generation fell by 8.4 per cent to 21.0 TWh and offshore fell by 5.8 per cent to 16.4 GWh. Wind speeds were lower than in 2015 which had been the highest in fifteen years, more than offsetting additional capacity for both onshore and offshore winds (table 6.4). Generation from hydro sources fell by 14 per cent to 5.4 TWh in 2016, although 2015 had seen the second highest rainfall during the preceding 15 years (table 6.4). Renewable Heat Renewable heat increased by 12 per cent due to increases in plant biomass and anaerobic digestion schemes supported by the Renewable Heat Incentive (RHI) The RHI supported 15 per cent of renewable heat in 2016, an increase of 4.0 percentage points on 2015 Introduction 6.1 Energy from renewable sources has been steadily increasing since 2000 as a result of national and international incentives including the EU Renewable Energy Directive which requires the EU as a whole to achieve 20 per cent of its energy from renewable sources by 2020 (the UK’s target is set at 15 per cent) (see the technical annex for a description of the policy context). The UK has a varied mix of renewable technologies including biomass which is a key fuel source in both electricity generation and heat. Wind, solar photovoltaics, hydro and shoreline wave and tidal also contribute to electricity generation and active solar, heat pumps and deep geothermal are used in heat generation (see the technical annex for descriptions of the sources of renewable energy). Liquid biofuels in transport also contribute to the separate RED transport target (for the UK, this is set at 10 per cent). Although solar photovoltaics was the leading technology in 2016 (a third of total capacity), in generation terms, bioenergy accounted for the largest proportion (36 per cent) followed by onshore wind (25 per cent) and offshore wind (20 per cent). 6.2 The renewable energy flow chart on page 154 summarises the flows of renewables from fuel inputs through to consumption for 2016 and includes energy lost in conversion; the data are sourced from the commodity balance table 6.1 and table 6.4 for electricity outputs. 153 Renewables flow chart 2016 (thousand tonnes of oil equivalent) 15 4 Note: This flow chart is based on data that appear in Tables 6.1 and 6.4 Renewable fuel demand (Tables 6.1 and 6.6) 6.3 The commodity balances tables for renewables (tables 6.1 to 6.3) show that a large proportion (83 per cent) of renewable fuel sources are produced domestically, largely due to the local nature of utilising natural resources such as wind, solar and hydro. However, bio energy fuels are transportable and a significant proportion is imported (27 per cent in 2016, including wood and liquid biofuels). Plant biomass showed the largest proportion of imports at 61 per cent, mainly wood pellets for electricity generation. 6.4 The balances also show for the first time, a transfer out from bioenergy. This represents biogas generated from farm waste digestion and injected into the gas grid. This has also been included for 2014 and 2015 as a revision (see paragraph 6.51). The amount transferred is then included as a positive transfer in the natural gas balance of chapter 4 (table 4.1). 6.5 Unlike other fuel sources, the renewables energy balances have zero statistical differences as the data are mostly taken from a single source where there is less likelihood of differences due to timing, measurement, or differences between supply and demand. 6.6 Table 6.6 shows how renewable fuel demand (excluding non-biodegradable waste) by source (i.e. on an input basis1) is split between electricity generation, heat and as a fuel in transport. Excluding non-biodegradable energy from waste, total demand in 2016 increased by 4.3 per cent, to 17,296 ktoe. This growth was due to an increase in bio energy demand, particularly in biodegradable energy from waste and anaerobic digestion used for electricity generation and also plant biomass used for heating purposes. 6.7 In 2016, 72 per cent of renewable energy demand was accounted for by bioenergy with wind accounting for 19 per cent. Chart 6.1 shows a comparison for the key renewables sources; Chart 6.1: Renewable fuel use 2016 1 For combustible fuels used to generate electricity, this refers to the energy value of the fuel source rather than the actual electricity generated. For heat generation and primary electricity sources (solar photovoltaics, wind, hydro, and wave and tidal), the output energy is deemed to be equal to the fuel inputs. 155 6.8 Whilst several renewable technologies are specific to either electricity generation or heat production, combustible fuels are used for both purposes. In 2016, 68 per cent of biomass was used in electricity generation. Chart 6.2 below shows a further breakdown of biomass by source and also how its use is split between heating and electricity generation. Chart 6.2: Biomass fuel use 2016 6.9 Where biofuels are used for generation, a comparison is made in the electricity generation section (paragraph 6.11) between the fuel input split and actual output generation. Comparison of fuel use in heat consumption and electricity generation (Tables 6.6 and 6.4) 6.10 While bioenergy dominates on a fuel input basis (chart 6.1), hydroelectricity, wind power and solar together provide a larger contribution when the output of electricity is being measured as chart 6.3 shows; Chart 6.3: Electricity generation by fuel source 2016 156 This is because on an energy supplied basis the inputs are deemed to be equal to the electricity produced for hydro, wind, wave and solar, i.e. are deemed to be 100 per cent efficient (see Chapter 5, paragraph 5.71). However for landfill gas, sewage sludge, municipal solid waste and other bioenergy sources a substantial proportion of the energy content of the input is lost in the process of conversion to electricity (6,075 ktoe in 2016), as the renewables flow chart (page 154) illustrates. 6.11 Generally growth in bioenergy fuels used in electricity generation will be similar to the growth in output generation unless there is a change in thermal efficiency (the amount of fuel required to produce a unit of electricity). Table 6.1 below shows the comparative growth rates between 2015 and 2016 for bioenergy fuel inputs and generation outputs; Table 6A: Growth in fuel inputs versus generation for bioenergy Growth between 2015 and 2016 Fuel use Generation (table 6.6) (table 6.4) Bioenergy: Landfill gas -3.5% -3.5% Sewage sludge digestion 6.3% 6.3% Biodegradable energy from waste 23.4% 6.0% Co-firing with fossil fuels -34.8% -35.9% Animal Biomass -2.2% 0.4% Anaerobic digestion 39.5% 39.5% Plant Biomass 0.6% 1.3% Total bioenergy 5.0% 2.7% 6.12 For the majority of biofuels, growth in fuel use is similar to generation growth with the exception of energy from waste. This is due to a drop in efficiency between 2015 and 2016. 157 Trends in Overall Electricity Generation and Capacity (table 6.4) 6.13 Although total generation capacity increased between 2015 and 2016 (by 16 per cent to 35.7 MW), generation actually fell (by 0.2 per cent to 83.2 GWh). Charts 6.4 and 6.5 below show the long term trends, highlighting 2016 as the first year to show a decrease (although generation supported by the Renewables Obligation showed an increase, by 0.8 per cent, table 6.4); Chart 6.4: Electrical generating capacity of renewable energy plant (1) All waste combustion plant is included because both biodegradable and non-biodegradable wastes are burned together in the same plant. (2) Hydro includes both large scale and small scale, and shoreline wave (13.5 MW in 2016). Chart 6.5: Electricity generation by main renewable sources 158 6.14 The fall in generation in 2016 is due to lower wind and hydro generation; wind speeds were considerably lower than in 2015 and rainfall (in the main catchment areas) was also comparatively low. This is despite an increase in wind generation capacity, mostly in onshore wind which increased by 18 per cent to 10.9 GW, ahead of closure of the Renewables Obligation (RO) on 31 March 2017 (see para 6.57). Hydro generating capacity also increased; although large scale capacity is fairly stable, small scale increased by 20 per cent though from a small base (0.3 GW).