UK homes could be left without power for three hours at a time as blackouts hit this winter, the National Grid has warned.

The first planned blackouts in decades might hit parts of the country if power plants can’t get enough gas to keep them running.

Households are being encouraged to help avoid blackouts by using more energy during off-peak times.

In the “unlikely" scenario of planned blackouts, the National Grid Electrictiy System Operator (ESO) said that households and businesses may face three-hour outages to ensure the grid does not collapse.

Alloa and Hillfoots Advertiser: PAPA (Image: PA)

It is the most dire of three possible scenarios that the ESO laid out on Thursday for how Britain’s electricity grid might cope with the worst global energy crisis for decades.

In the other two scenarios, the operator hopes that by paying people to charge their electric cars at off-peak times and firing up backup coal plants it can offset the risk of blackouts.

The margins between peak demand and power supply are expected to be sufficient and similar to recent years in the National Grid Electricity System Operator’s (ESO) base case scenario for this winter.

But in the face of the “challenging” winter facing European energy supplies following Russia’s invasion of Ukraine, the grid operator is also planning for what would happen if there were no imports of electricity from Europe.

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.

National Grid Gas Transmission separately said that while gas demand will increase this winter, it expects Britain to be able to get enough gas to take it through a Beast from the East scenario or a long, cold winter.

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.

Households tend to consume a fifth of their daily energy between 4pm and 7pm, according to data from Ovo Energy. The supplier on Thursday said its customers could save £100 if they signed up to use energy at off-peak times.

Alloa and Hillfoots Advertiser: PAPA (Image: Radar AI)

In addition, larger businesses will be paid for reducing demand, for example by shifting their times of energy use or switching to batteries or generators in peak times.

The “demand flexibility service” will run from November to March, and 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.

It is hoped it will deliver 2GW of power savings to balance supply and demand.

The ESO’s director of corporate affairs, Jake Rigg, 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, so watch out for further details soon. This really is a window into the future where a flexible energy system will be cleaner and lower cost to alternatives.”

The ESO also warned 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.

Responding to the winter outlook, a Government spokesman said: “The UK has a secure and diverse energy system.

“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 spokesman 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.

Energy regulator Ofgem said: “We have one of the most reliable energy systems in the world and we are in a favourable position.

“However, it is incumbent on a responsible and prudent energy sector to ensure the right contingency measures are in place.”