The electricity network owner National Grid has suggested that shops and factories could be paid to ration electricity amid increased fears over the likelihood of nationwide power blackouts.
The National Grid has suggested large consumers could be asked to decrease use between 16:00 and 20:00 on weekdays in the winter.
The network owner was responding to warnings from the regulator Ofgem that the risk of blackouts had doubled in less than a year because ageing power stations were not being replaced.
However the government has dismissed the proposals and insisted that the lights would stay on.
Energy Minister Michael Fallon told BBC 2's Newsnight: "I can assure you the lights are not going to go out."
He said: "The latest assessment has shown that the position is slightly worse than the previous assessment last year and they have got to make sure, the regulator Ofgem, has got to make sure, with all the tools at its disposal, bringing some mothball plants back in action, it has got to make sure that the lights stay on and they will."
A Department of Energy and Climate Change spokesman added: "If necessary, steps such as bringing mothballed plant back online will ensure we have enough power in the short term. Power is not going to be rationed and businesses are not going to be forced to switch off.
"A capacity market will ensure we have enough power in the longer term."
Yesterday Ofgem warned that the risk of Britain suffering a major power blackout will rise significantly towards the middle of the decade as ageing generators retire from service.
The regulator said the margin of supply capacity over demand could narrow to between 2 per cent and 5 per cent by 2015 and 2016.
Previous estimates suggested that electricity supply capacity would fall to 4% at its lowest.
If capacity were to reduce to 2% it would increase the risk of blackouts towards the middle of the decade.
Ofgem said the findings "illustrates the need for the timely implementation of the Department of Energy and Climate Change's capacity market".
"The risk to electricity supplies is projected to increase from the current near zero levels, although Ofgem does not consider disruption to supplies is imminent or likely, providing the industry manages the problem effectively."
Ofgem also highlighted uncertainty around supply and demand for electricity.