Lesley Riddoch says: "Some people hate wind farms. I have met few of them and am far more aghast at the recent hike in energy prices" (Opinion, 7 January).

The wind may be clean and free, but wind-generated electricity fed into the grid is neither because of the power station back-up required for such an unreliable source. Back-up is required because coal-fired stations cannot be rapidly adjusted to suit wind variation. Since there is no fossil displacement there are costs, monetary and in emissions. These costs are ignored in the claims of wind farm companies.

Government supports in the form of the Renewable Obligation and the Climate Change Levy ensure wind farm electricity sells for less than other generation. These subsidies are paid for by the consumer and play a part in recent price increases.

A public accounts committee report in 2005 claimed British taxpayers would subsidise wind farms by £6.5 billion by 2010 and that the Renewables Obligation would add £1 billion a year to electricity prices by then. The bill for renewable sources of energy will continue to soar after that, rising to £12.5 billion by 2015.

Edward Leigh, the committee chairman, said: "Consumers are providing a massive subsidy to the renewables industry, but, unlike public expenditure, this subsidy does not receive annual scrutiny by parliament. This is unacceptable."