Because even if, say, offshore wind costs the same as natural gas by 2015 (as predicted by German utility E.ON), there is still an extra cost of building backup power for when the wind doesn't blow.

This has dealt a heavy blow to the industry's hitherto bullish mood, according to a survey published on May 4th by Oil &Gas UK, a lobby group.

By utilization of the existing boiler a horizontal combustion furnace and a burner that match have been designed for the recovery of the latent heat in the blow gas.