Energy companies are cashing in on Government subsidies by building wind farms that will never make any money because they are being constructed on sites with not enough wind, it has been claimed.
To meet EU targets for renewable energy, the Government has subsidised the wind turbine industry by half a billion pounds. Yet companies have not managed to deliver even 0.5 per cent of Britain's electricity needs.
Britain must produce 20 per cent of its energy from renewable sources by 2020, a target that the Government admits it is struggling to meet.
Companies that meet green energy targets receive Government cash under the Renewables Obligation Certificate Scheme (ROCs). Experts told Costing the Earth on Radio 4 that claims of wind farm potential were being overestimated by companies keen to receive subsidies.
Michael Jefferson, policies chairman of the World Renewable Energy Network and former chief economist with Shell, believes the industry is encouraged to exaggerate wind speeds and the amount of potential wind energy a farm can supply.
He believes there are many poorly sited farms in England, particularly in areas with relatively little wind such as the Midlands.
"We should be putting our money where the wind is and that is quite often not where the development pressure is," Mr Jefferson said.
Jim Oswald, an engineering consultant, analysed figures submitted to the electricity watchdog Ofgem on every wind farm's load factor - the amount of wind generated across the year.
The recommended load factor for a viable wind development is 30 per cent, but he said the average across Britain was 28 per cent. The problem lied with the volatility of the wind, he added.
Britain is not consistently windy enough to generate a regular energy supply and there is no way of storing wind energy, a drawback in a country that sometimes experiences strong winds, but often no wind at all.
"It's the power swings that worry us. Over a 20-hour period you can go from almost 100 per cent wind output to 20 per cent."
An over reliance on wind power could result in power failures and higher electricity bills, he said, adding that the network needed to be redesigned.
The British Wind Energy Association (BWEA) rejected the claims. It said subsidies were not paid for the building of farms, only per unit of electricity supplied to the National Grid.
Maria McCaffery, the chief executive, said: "Nobody in their right mind, not a developer and not the Government, would support the building of a wind farm where the wind speeds are not high enough to generate a viable amount of electricity. It's absolute nonsense."
"The only pertinent figure is the amount of electricity actually supplied and there is a fixed amount of subsidy per unit of energy. You are only subsidised for what you produce."
She said most farms would be generating some electricity for 85 per cent of the time.
She admitted that not every wind farm could be located in areas of highest wind speed, but instead the industry had to identify areas where wind speeds were "good enough" to be economically viable.
Mr Jefferson and Mr Oswald criticised the fact that some wind farms in remote areas such as northern Scotland were sitting idle because they were not connected to the National Grid.
But Ms McCaffery said the connection backlog was being tackled and in the meantime these plants were not receiving subsidy.
Malcolm Wicks, the energy minister, has insisted that wind energy is an important part of Britain's energy needs.
He said the Government was encouraging more offshore wind farms combined with tidal and marine power plants.
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