Wind farms can never be relied upon to keep the lights on in Britain because there are long periods each winter in which they produce barely any power, according to a new report by the Adam Smith Institute.
The huge variation in wind farms’ power output means they cannot be counted on to produce energy when needed, and an equivalent amount of generation from traditional fossil fuel plants will be needed as back-up, the study finds.
Wind farm proponents often claim that the intermittent technology can be relied upon because the wind is always blowing somewhere in the UK.
But the report finds that a 10GW fleet of wind farms across the UK could “guarantee” to provide less than two per cent of its maximum output, because “long gaps in significant wind production occur in all seasons”.
Modelling the likely output from the 10GW fleet found that for 20 weeks in a typical year the wind farms would generate less than a fifth (2GW) of their maximum power, and for nine weeks it would be less than a tenth (1GW).
Output would exceed 9GW, or 90 per cent of the potential, for just 17 hours.
Britain currently has more than 4,500 onshore wind turbines with a maximum power-generating capacity of 7.5GW, and is expected to easily surpass 10 GW by 2020 as part of Government efforts to tackle climate change.
It is widely recognised that variable wind speeds result in actual power output significantly below the maximum level – on average between 25 and 30 per cent, according to Government data.
However, the report from the Adam Smith Institute found that such average figures were “extremely misleading about the amount of power wind farms can be relied up to provide”, because their output was actually “extremely volatile”.
“Each winter has periods where wind generation is negligible for several days,” the report’s author, Capell Aris, said.
Periods of calm in winter would require either significant energy storage to be developed – an option not readily available – or an equivalent amount of conventional fossil fuel plants to be built.
Suggestions that a pan-European electricity grid would help to provide extra security are also false, because northern European wind power is similarly unreliable, it found.
“Wind farms are a bad way of reducing emissions and a bad way of producing power”, said Ben Southwood, head of policy at think tank the Adam Smith Institute.
“We may want to reduce carbon emissions, but nuclear and gas are our best ways of doing that until cheap energy storage options are available on a vast scale”, he added.
The Conservatives have vowed to end subsidies for new onshore wind farms if they win the 2015 election on the grounds there are already more than enough with planning consent to hit EU green energy targets.
Ministers estimate that 11-13GW of onshore wind farms will be needed by 2020 to hit the targets, while official analysis suggests 15GW is likely to be built.
Jennifer Webber, director of external affairs at wind industry body Renewable UK, said: “All source of electricity provide varying amount of power, but last year wind provided enough electricity for over five million homes, and contributed to a decrease in the amount of fossil fuels we burned for electricity.
“This year we’ve seen records for amounts of electricity from wind broken overwhelmingly regularly as wind has stepped up to the plate when other sources have been struggling, and recently there have been periods where it’s overtaken both nuclear and coal on the grid, showing it’s already a major part of the electricity mix.
“National Grid, who are the people who actually manage the electricity system, have said that they’re managing wind on the system well, they have good forecasts and they’re able to significantly expand it.”
A Government spokesman said: “We need a diverse energy mix that includes renewable sources like wind which work alongside nuclear and technologies like carbon capture and storage so we can continue to use fossil fuels in a cleaner way.”
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