(Bloomberg) --

The UK’s grid operator asked three coal-fired power units to be ready to generate on Monday as it boosts electricity supplies during the current cold snap.

It’s the first time this winter National Grid Plc has needed to call on the reserve. The units are warming up and will be ready to generate electricity early Monday if needed. Demand is set to surge during a spell of freezing weather in the UK even as wind speeds drop, curbing supply.

The grid “as a prudent system operator has these tools for additional contingency to operate the network as normal and the public should continue to use energy as normal,” National Grid’s Electricity System Operator said in a statement.

Later, the company said it will use a tool that pays some homes to reduce consumption between 5 p.m. and 6 p.m. Monday when forecasts show margins will be tighter than normal. The so-called demand flexibility service was tested during a cold spell in December.

“This does not mean electricity supplies are at risk and people should not be worried,” National Grid said on Twitter. “These are precautionary measures to maintain the buffer of spare capacity we need.”

The UK will phase out coal next year as it seeks to cut emissions from the power sector. But the government asked coal-fired power producers to keep units available this winter as Europe faces a shortage of natural gas. Using coal means less gas is needed to produce power.

Freezing fog is forecast to grip Britain overnight into Monday, sending temperatures tumbling. The cold weather is set to last this week, according to Bloomberg’s weather model. Wind generation will be low through Tuesday.

Demand is expected to peak at 42.2 gigawatts at 5 p.m. on Monday, up from 40.2 gigawatts on Sunday, grid data show. Power for tomorrow rose to £187.67 a megawatt-hour, the highest since Dec. 21 on the N2EX exchange. The contract for 5-6 p.m. jumped to £260.40 a megawatt-hour on Epex Spot SE.

Britain is the second-biggest market for offshore wind in the world and is particularly exposed to troughs in generation as it relies heavily on expensive gas for backup. Prices have eased after a run of mild weather allowed Europe to keep more gas in storage than expected. UK futures are still more than double the usual levels for this time of year, according to ICE Endex data.

Drax Plc’s units 5 and unit 6 and a unit at Electricite de France SA’s West Burton have been asked to get ready. These are two out of three stations that negotiated a winter contingency contract with National Grid for this winter following a request from the government.

(Updates with request for households to use less in fourth paragraph.)

©2023 Bloomberg L.P.