Britain could face three-hour planned power cuts to homes and businesses this winter if it cannot import electricity from Europe and struggles to attract enough gas imports to fuel gas-fired power plants, the National Grid warned on Thursday.
The prospect of power cuts comes as Prime Minister Liz Truss on Thursday called on Europe to keep energy exports flowing during the winter, and is likely to heap further pressure on the government after she previously ruled out energy rationing in Britain.
Countries across Europe are drawing up winter contingency plans against the disruption of flows of gas from Russia because of the war in Ukraine, which could lead to rationing and a curb in exports of energy to other countries.
A shortage of gas in Europe, as well as maintenance issues with several French nuclear power plants, have raised the risk Britain could be unable to secure the gas it needs or the imports of electricity it typically receives from countries such as France, Belgium and Netherlands.
"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 National Grid Electricity System Operator (ESO) said in its Winter Outlook.
The British government said in response it was confident of securing power supplies for the winter.
"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," a government spokesperson said.
"To strengthen this position further, we have put plans in place to secure supply," the spokesperson added, pointing to Britain's North Sea gas reserves, imports from partners like Norway and clean energy sources.
A separate risk assessment by the British government published on Thursday showed its security of gas supply met the standards required in law.
Its analysis said the infrastructure could meet gas demand across scenarios including "a combination of exceptional demand caused by severe weather conditions and the failure of the largest single piece of infrastructure on the gas network".
Russia has slashed its gas supplies to Europe this year and while Russia only meets about 4% of Britain's gas needs, a disruption in supply to Europe has contributed to driving up British prices and makes it harder for Britain to secure gas from others.
"The potential for a shortfall in gas supplies within continental Europe could have a range of knock-on impacts in Great Britain, creating risks around the ability of GB to import from continental Europe," National Grid's Gas Transmission (NGGT) arm said in a separate Gas Winter Outlook.
The gas outlook said Britain's ability to secure supply would depend upon its gas prices being high enough to continue to attract exports from Europe and liquefied natural gas (LNG) from countries such as Qatar and the United States.
"In the unlikely event there is insufficient gas supply available in GB to meet demand ... We have the tools required to ensure the safety and integrity of the gas system in the event of a Gas Supply Emergency," NGGT said.
As a first step, these tools include sending notices to the market to try to attract more gas to the system or to get large gas users to reduce demand.
If a lack of gas meant Britain was forced to limit supplies, households would be prioritised and curbs would first fall on large industrial users and power plants.
Both National Grid ESO and NGGT said they expect to be able to meet electricity and gas demand this winter but that the unprecedented and uncertain situation in Europe had led them to look at a range of scenarios.