Centrica, GDF Suez/International Power and Scottish & Southern Energy are among the UK companies to have reduced or switched off capacity at older plants.
And despite ceasing to produce electricity, the energy companies still receive the carbon credits which they can trade on international markets – giving substantial windfalls.
All the named companies announced temporary or permanent shut-downs in recent weeks – just after this year's carbon allowances were handed out by February 28.
Centrica has put four plants – Barry, Brigg, Peterborough and Kings Lynn – into "preservation mode", which means they are not producing but ready to be switched on.
Meanwhile, GDF Suez has reduced output at its Teesside plant to almost nothing – with the station expected to produce just 45 megawatts out of its 1875 megawatt capacity. (read more)