Two coal units at British power plants have been placed on standby to deal with tightened supplies on the UK’s electricity network.
The National Grid ordered the units to be warmed up on Sunday night in case more energy sources are needed.
The move coincides with the arrival of a cold snap and follows a sudden drop in wind generation.
Temperatures plunged below freezing across much of England and Wales on Sunday night and are expected to remain frosty through to Monday night.
A Met Office cold weather warning remains in place until 6pm on Tuesday.
The combination of colder weather and volatile supplies from wind power has heaped pressure on the power grid in recent weeks.
Wind power has become one of the main sources of electricity generation in the UK in recent years, often surpassing gas during the last two winters.
But it remains susceptible to sudden large drop-offs, forcing the UK to import electricity from Europe or ramp up fossil fuel generation.
The latest data on the UK’s energy mix shows the amount of daily power supplied by wind generation has halved since Thursday, while several gigawatts of electricity were imported from France.
The country had to rely on last-minute supplies of power from the French and Dutch networks – which are supplied to the UK via undersea cables – during a supply scare last month.
National Grid blamed a fault on the network in southern England and confirmed that no homes or other properties lost power during the incident.
Rolling blackouts were laid out as a possibility in the body’s worst-case scenario predictions this winter but have been avoided so far .
It has largely refrained from using the flexible energy scheme in which people are paid to use less power during peak times.
The so-called Demand Flexiblity Service (DFS) was activated for the first time on January 23 and ran for two days with no disruption to the power grid.
The coal units which have been placed on standby are located at EDF’s West Burton A plant and Uniper’s Ratcliffe-on-Soar plant, both in Nottinghamshire.
The grid’s electricity system operator (NGESO) said the order is ‘not confirmation that they will be used’ but that they ‘will be available if required’.
A spokesperson added: ‘NGESO as a prudent system operator has developed these tools for additional contingency to operate the network as normal.
‘This does not mean electricity supplies are at risk.’
Get in touch with our news team by emailing us at [email protected] .
For more stories like this, check our news page .