"They are using new metals in the generators that cut the need for servicing. There are cameras to relay digital data through cloud computing that can reset the turbines. You have to be bullish," he said.

Onshore projects in Texas, Iowa, and China’s northern plains are now among the cheapest forms of energy in the world, but this has little relevence to most of Britain. Land prices are higher here and the population is denser. Onshore wind has almost reached the limits of social acceptance. It will increase a little further but may peak near 11 GW by 2020.

The UK debate is essentially over offshore wind. This source used to be twice as expensive - with subsidies to match - but the gap is narrowing fast. Dong Energy has just signed an offshore deal in the Netherlands at less than £63 per megawatt hour (MWh), with sweetners from the Dutch state. “This reflects what the industry is now capable of delivering in general,” said Samuel Leupold, Dong’s executive vice-president.

"Offshore wind is a very young technology. The equipment we are using is completely different from what we had even four or five years ago. The foundations use less steel, the cranes are getting lighter," he said.