Households are to be paid to put on their dishwashers or washing machines or charge their electric cars away from peak hours as part of efforts to prevent blackouts this winter - despite expected falls in energy consumption.

Energy network operator National Grid ESO is bringing in a “demand flexibility service” running from November to March, to ensure people are rewarded for making energy savings.

It is hoped it will deliver energy savings of 2GW - enough to power an estimated 1.5m homes - to balance supply and demand.

It is expected to swing into action 12 times whatever happens to ensure people get rewarded for being part of the scheme – with additional use if needed to protect supplies.

The National Grid said that shortages of gas, which generated 40% of UK electricity last year, could mean planned three-hour blackouts in some areas to protect supplies for heating homes and buildings, system operators warned.

Analysts say drought affecting hydropower, nuclear outages, and gas shortages caused by Russia's war on Ukraine are highlighted as risks to the electricity system this winter.

The blackout fears come despite predictions that use of energy will drop this winter, compared to last, as households across the country cut back due to soaring energy bills.

The energy market regulator Ofgem in response to the new measures said it was "incumbent on a responsible and prudent energy sector to ensure the right contingency measures are in place".

Scots anti-fuel poverty campaigners have questioned how the National Grid's scheme could work with less than half of the population on smart meters.

UK ministers have so far played down any talk of a threat to winter energy, sayinag in August that the UK’s “highly secure and diverse gas and electricity system” had prepared the UK for “all and every eventuality”.

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And Liz Truss also ruled out rationing when she was campaigning to become Conservative party leader and Prime Minister.

The European Union is already preparing for widespread blackouts as a result of an energy supply crunch tied to the war in Ukraine.

The European Union is shoring up its resources as temperatures drop and preparing for two “conceivable scenarios” - one in which a few member states experience power cuts, and another in which blackouts occur in many member states at the same time.

Analysts say that due to outages on its nuclear fleet, France has been importing power from Britain, and Norway has warned it may have to curb exports because of failing hydropower reserves.

National Grid (ESO) says in its base case winter scenario that the margins between peak demand and power supply are expected to be sufficient and similar to recent years.

But in the face of the “challenging” winter facing European energy supplies the grid operator is also planning for what would happen if there were no imports of electricity from Europe and insufficient gas supplies.

To tackle a loss of imports from France, Belgium and the Netherlands, there are two gigawatts of coal-fired power plants on stand-by to fire up if needed to meet demand.

People are being encouraged to sign up with their electricity supplier to a scheme which will give them money back on their bills to shift their use of power away from times of high demand to help prevent blackouts.

That could mean putting on the dishwasher or washing machine overnight or charging an electric vehicle at off-peak times.

Larger businesses would be paid for reducing demand, for example by shifting their times of energy use or switching to batteries or generators in peak times.

The National Grid ESO's corporate affairs director, Jake Rigg, said that fuller details of the demand flexibility would be available at a later date.

He said: “The demand flexibility service is a first of its kind and a smart way for signed up consumers in homes and businesses to save money and back Britain.

“If you put your washing machine or other electrical appliances on at night instead of the peak in the early evening, you can get some money back when we all need it.

“The service is due to launch in November.... This really is a window into the future where a flexible energy system will be cleaner and lower cost to alternatives.”

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Without the scheme, there might be days with high demand and low levels of wind power – when there would be a potential need to interrupt supply to some customers for limited periods, National Grid ESO’s outlook said.

The grid operator also warned in a worst-case scenario that if there is not enough gas to keep the country’s power stations going in January it could force distributors to cut off electricity to households and businesses for three-hour blocks during the day.

“In the unlikely event we were in this situation, it would mean that some customers could be without power for pre-defined periods during a day – generally this is assumed to be for three-hour blocks,” the ESO said.

It said the number of people left without electricity would depend on how many gas power stations would be forced to shut down because there is not enough gas.

Its base case assumes that when Britain needs more electricity, cables that link the country to its European neighbours will be enough to keep the lights on.

But it did not assume that there is any “material reduction of consumer demand due to high energy prices”.

The National Grid outlook comes as energy analysts LCP have claimed that Britain's power supplies are at risk of running short for ten hours this winter if the nation is unable to import power from continental Europe.

Due to power shortages on the continent, LCP has said that it is "very possible" that Europe will not be able to meet Britain's electricity needs this winter.

As a consequence, power supplies failing to match demand for ten hours could rise to 29 hours if ministers had not already stepped in to keep coal-fired power plants open.

A Government spokesman said in response: “The UK has a secure and diverse energy system.

“We are confident in our plans to protect households and businesses in the full range of scenarios this winter, in light of Russia’s illegal war in Ukraine.

“To strengthen this position further, we have put plans in place to secure supply and National Grid, working alongside energy suppliers and Ofgem, will launch a voluntary service to reward users who reduce demand at peak times.”

The spokesperson said Britain is not dependent on Russian energy imports, and has access to North Sea gas reserves, imports from Norway, and via ports which can handle liquefied natural gas, as well as clean energy sources.