Customers have no incentive to conserve power when it is scarce during times of peak demand, so generating firms have to build lots of spare capacity to cope with surges in consumption.

They have been postponed three times already, and the money that has been made available to pay for them is so scarce that many people fear they may not happen at all.

These are heated times: the number of comparative (or "attack") advertisements is growing, as companies battle for scarce consumer dollars amid the recession.