Take the £92.50/MWH strike price agreed between DECC and EDF for the two new nuclear reactors at Hinkley Point. At the current market price of £52/MWH EDF would be paid £40.50/MWH by a levy on our bills. If the price came down to the German level of £44/MWH, the compensation to EDF would be £48.50/MWH. As for offshore wind, with its strike price of £140/MWH, the costs will be astronomical.

Finally, there is the question of shale gas: how much there is, how much is recoverable, how much it will cost — and will ingrained British nimbyism ever let proper exploration begin?

After three years of inaction, the Coalition decided to encourage, cautiously, exploratory drilling, starting in politically sensitive West Sussex. In the next year or so we can expect more drilling of the Bowland Shale in Lancashire, where two well-funded companies, Cuadrilla and Igas, have substantial concessions. Centrica, owner of British Gas, has "farmed in" to the Cuadrilla operation, paying £60 million to fund six wells.

The British Geological Survey (BGS) report into shale potential was published by DECC earlier this year after lengthy political delay. It mostly confines itself to an assessment of the Bowland-Hodder Shale, which runs across the country from the Lancashire coast to Yorkshire, Humberside and Lincolnshire, and as far south as Derby. The BGS central case is that there are 264 trillion cubic feet (tcf) in place, which compares with Cuadrilla's estimate of 200 tcf in just its concession around Blackpool. At this stage, any attempt to estimate how much of this can be technically produced, let alone at an economic cost, is guesswork. However, going by American experience, a conservative estimate is that 10 per cent of gas in place can be produced economically: 20 tcf from Cuadrilla's area, or 26 tcf from the wider area considered by the BGS.

To put this into context, the North Sea has produced 85 tcf since 1970, and remaining proved reserves are 8.7 tcf. These numbers are elastic, and depend on price, fiscal regime, technology and geology. But they demonstrate that in time Britain's shale resources should prove nearly as important as the North Sea has done.