UK energy policy has one key predicate, namely that fossil fuels are going to get inexorably more expensive. This is, not to put too fine a point on it, the sine qua non of the whole renewables programme. Renewables, we are told, will save consumers money, and only if we dig much deeper might we discover that in fact we are actually being told that renewables are being forecast to be cheaper than fossil fuels in the future.
For years that forecast has looked ever more implausible, as all around us a revolution in unconventional oil and gas has caused fossil fuel prices to fall. Now, finally, the government has been forced to respond and to reduce its forecast prices.
Burning gas for power is currently far cheaper than electricity from wind farms, which receive billions of pounds in subsidies from consumers.
Yesterday however the Department of Energy and Climate Change released new forecasts slashing its power and gas price forecasts for later this decade by as much as 20 per cent.
But ministers have repeatedly argued that gas prices will keep on rising, eventually making green energy good value for money.
This is a bit of a nightmare for the greens in government, and it is hard to imagine that the government and its advisers are not going to have to reassess the whole renewables programme. No doubt it is not beyond the wit of the bureaucrats in DECC to come up with some plausible explanation of why renewables will get much cheaper in the future, but it will be interesting to see just how much they have to wriggle first.