Under the CfD, the generator is guaranteed his strike price for 20 years, or longer in the case of nuclear. If the market price is lower than the strike price he will be paid the difference via a charge on consumer bills; if the market price is higher, then he pays back the difference. In theory this is a better deal than the renewables obligation, which guarantees a premium whatever the market price. However, any advantage obtained under the CfD system would depend on a big increase from the current wholesale price. If, as many observers believe, wholesale prices go down in the coming years, CfDs will become more expensive than the renewables obligation.

In addition, the Coalition has imposed a "carbon price floor", essentially a tax on the main sources of electricity, coal and gas. This began in April this year at the relatively modest level of £4.94 per ton of CO2, doubling in 2014 and doubling again in 2015. By 2017 the carbon price floor will be £24.62/ton. Such figures mean little to the average person, but in the real energy market they amount to a tax on natural gas of £0.91/MWh in 2013, building up to £3.30 in 2015, £4 in 2016 and £4.50 in 2017. Forward gas currently trades around £60/MWh, so within four years the carbon price floor will be increasing the wholesale cost of gas by 7.5 per cent. This is not negligible, but it is unique in Europe: our competitors are not similarly hamstringing themselves.

There is also the £2.6 billion/year Energy Companies Obligation (ECO). Under the rules of ECO, energy suppliers are set targets to improve the energy efficiency of their domestic customers' buildings. DECC blandly describes the financial arrangements as being funded by the energy suppliers. Of course they are-via a surcharge on all customer bills. One utility, SSE, recently said ECO would add £100 to the average bill.

There are many other costs of government intervention in energy markets. The largest of those not directly related to the cost of energy itself is the expansion of the National Grid required to transport wind-generated electricity from the north of Scotland or — the really expensive bit — from the offshore wind sector in which the government places so much faith.

National Grid is a regulated monopoly which agrees investment targets and an allowable rate of return with Ofgem. It has decided that the likely amount of investment from 2013 to 2020 should be £20 billion. But this is a movable target: if more renewable generators require more transmission capacity National Grid will supply it. And the entire cost will be passed to the customer. Colin Gibson, the former power networks director for National Grid, calculates that in 2020 the system costs required by the future wind turbine fleet will be in the region of £5 billion a year.