Government's green energy plan may cost 17 times more than its benefits

The Government's plans to increase the proportion of Britain's energy generated by "green" sources is set to cost between 11 and 17 times what the change brings in economic benefits.

The figures are buried deep in the Government's Renewable Energy Strategy paper produced last month.

According to the document, while the expected cost will total around £4bn a year over the next 20 years, amounting to £57bn to £70bn, the eventual benefit in terms of the reduced carbon dioxide emissions will be only £4bn to £5bn over that entire period.

The figures make up part of the Government's impact assessment of the policies, which include plans to raise the proportion of British electricity produced by renewable sources from 5.5pc today to 30pc.

It is the Government's assessment that the non-monetary benefits of the policies will compensate for the possible £65bn shortfall, but economists are sceptical as to how much of this sum such factors can make up.

The White Paper has also calculated that household gas and electricity bills will have to rise by up to £249 a year, although Energy and Climate Change Secretary Ed Miliband has insisted that new measures to improve consumers' energy efficiency would reduce the extra cost to an average of £92 a year per home.