Britain’s electricity generators have been asked by National Grid ESO to warm up coal-fired power stations this winter several times to provide a back-up supply if wind turbines do not generate enough energy.

This is part of National Grid ESO’s winter contingency contracts with coal power stations, including Drax power station in Yorkshire and EDF’s West Burton as a step to mitigate the risk of power cuts in periods of high demand.

Industry sources told ELN that warming a coal-fired unit involves a series of technical tasks which prepares the plant to run safely, including removing gases from the boiler and bringing its turbines up to speed so it can synchronise with the grid.

It is estimated that Drax, in collaboration with National Grid, sourced an additional 400,000 tonnes of coal, which together with the existing stock it holds, is enough for nearly 1TWh of electricity generation.

Given the very limited utilisation of both Drax and West Burton A units so far and with only two months of winter remaining, questions have been raised over what will happen to this coal.

The ESO said: “The stations will only be instructed by ESO to generate under the winter contingency contracts in response to system conditions. We are not fully through winter yet, however, any remaining coal on site at the end of the contracts will be sold back to the market.

“On next winter, we continue to work closely with BEIS and Ofgem to understand any requirement for additional non-gas generation beyond the end of these winter contingency contracts.”

The grid operator had previously estimated that these contracts would cost up to £395 million and will be recovered through the Balancing Services Use of System between 1st October 2022 and 31st March 2023.