Great Britain’s grid operator warns again over power supplies in heatwave

Neso asks generators to provide extra electricity on Friday evening to meet demand from fans and air conditioning

Great Britain’s energy system operator has raised the alarm over electricity supplies for the second time this week as a heatwave continues to disrupt Europe’s energy markets.

The National Energy System Operator (Neso) issued a notice late on Thursday asking generators to provide any extra electricity possible to Friday evening to help meet rising demand as households turn on air conditioners and electric fans to cope with the heat.

The operator said that it was calling for extra power supplies because its forecasts showed “tight margins on the electricity system” for Friday evening due to “the impact of extremely high temperatures affecting Great Britain and the continent”.

The government-owned body added that the electricity supply was not at risk, indicating that a blackout is not imminent.

The market warning was the second this week after Neso called for backup on Tuesday night before a rise in demand on Wednesday evening when the high pressure heat dome that has led to Europe’s worst heatwave ever was forecast to slow wind speeds in a blow to renewable energy supplies.

The operator was forced to pay sums well above the usual market price to generators that were able to ramp up their electricity output, which will ultimately be paid for through household energy bills.

It is estimated have paid out about £10m for a few hours of electricity supplied on Wednesday evening, mostly to gas power plants. Similar high payments are expected to secure supplies for Friday evening, while power plants across Europe have been forced to shut down owing to the record temperatures.

Several gas power plants in the UK have cut their output because of the heat. In France, which supplies a significant proportion of the UK’s electricity, four nuclear power plants reported unplanned outages because the temperature of nearby river water had climbed too high to be used cool the reactors.

The French state-owned utility company EDF said on Friday it would allocate €80m (£69m) to equip schools, nurseries and daycare centres with cooling systems to help them cope with future heatwaves.