Great Britain’s grid operator has released a rare summer power supply warning for Wednesday evening as the heatwave is expected to get more intense, putting pressure on the energy system.
The National Energy System Operator (Neso) issued an electricity margin notice late on Tuesday, asking power plant owners to provide any extra electricity, as the buffer between supply and expected demand comes under pressure.
“This is due to the impact of extremely high temperatures affecting Great Britain and the continent and low wind,” a Neso spokesperson said.
They added that the electricity supply was not at risk and the notice did not mean a blackout was imminent.
Neso – which manages the energy systems in England, Scotland and Wales – said it needed an extra 1,900 megawatts of power-generating capacity to avoid falling short of the electricity required to power homes and businesses within its normal safety margins.
The update is a notice to Britain’s electricity generators to provide any extra power they can from their plants, which could come at a significant cost to the operator.
Demand for electricity is expected to climb between 7pm and 10pm on Wednesday as people turn on electric fans and air conditioning units in an attempt to keep cool amid soaring temperatures.
It is more common for Neso to issue such notices during particularly cold spells in winter, when there is more demand for heating.
Electricity prices have risen sharply across European markets in recent days, as the heatwave has gripped much of the continent, pushing demand higher and also causing a string of power plant outages.
An area of high pressure has trapped heat across the region, slowing wind speeds, which has knocked renewable energy generation. There has also been lower output at some nuclear plants in France, where high river water temperatures are making it more difficult to cool the reactors.
The combination of rising electricity demand and falling generation across Europe has pushed market prices to multiyear highs.
Record temperatures for June of 38C are expected across south-east England on Wednesday, with a maximum of 39C on Thursday, which would easily overtake the previous June high of 35.6C.
The sweltering heat is expected to put pressure on the UK’s infrastructure, and train operators have urged passengers to travel only if necessary on Wednesday and Thursday, while schools have been closed across southern England and Wales and hospital appointments have been cancelled.
Several trade unions, including the Trades Union Congress, the Bakers, Food and Allied Workers Union and the Fire Brigades Union, have called for workers to take part in a strike on the hottest day.
There is no maximum legal temperature for workplaces in the UK, although there is a minimum legal temperature of 16C in offices.