3 September 2010 Last updated at 09:16 ET

Cornwall wind turbines output figure 'nonsense'

By Jonathan Morris BBC News, Plymouth

Good Energy claims on its website that more than 7,800 homes will get power from the new turbines

Claims that four new wind turbines will provide power for nearly 8,000 homes in Cornwall have been branded "nonsense" by an expert.

Good Energy, which is installing the turbines at Delabole, says its figures are based on average household energy use by the Department of Energy (DoE).

But figures from the DoE put the figure at about 5,700 households, calculated by Professor Michael Jefferson.

Good Energy stands by its figures for the turbines.

'Essential step'

The four new turbines will have a total combined capacity of 9.2MW (megawatts), enough to supply "over 7,800 homes" with electricity, says Good Energy.

It bases its calculation on 32% efficiency of the turbines and energy usage per home of 3,300kwh (kilowatt hours), a figure it says comes from the DoE and Ofgem.

Yet the DoE said while the figure of 3,300kwh was "acceptable", it based calculations for windfarms on 4,500kwh.

The larger energy use figure makes the actual number of houses supplied 5,731, said Professor Jefferson of the London Metropolitan Business School.

Mr Jefferson, a professor of International Business and Sustainability, told BBC News: "Never, ever, have I come across a figure as low as 3,300 kwh."

He said in an email to Good Energy: "Good Energy claim their Enercon turbines will power nearly 8,000 households.

"With respect, that must be nonsense."

Good Energy said: "We based our figure of 7,800 homes on this annual amount being 3,300kwh of electricity, which is the figure used by both Ofgem and Department of Energy and Climate Change."