UK grid operator issues second heatwave power supply warning this summer

Summer typically places less strain on the electricity grid, but the UK's energy network operator has warned that "extreme temperatures" from this week's heatwave could affect power supplies on Thursday evening, as households using fans and air conditioning place record pressure on the system.

The National Energy System Operator (Neso) has issued a rare evening notice calling on energy companies to provide additional supply to meet demand from cooling equipment. This marks the third heatwave to hit the UK this summer.

Second Warning in Two Months

This is the second time in two months that Neso has issued such a warning. During a heatwave in June, the organisation was forced to request additional power supplies when temperatures reached a record 37.7°C.

Neso stated that the UK grid faces a supply gap of approximately 1.2 gigawatts during peak evening demand, adding that it is "giving participants the opportunity to offer any additional generation or flexibility during the forecast period."

"Our forecasts show that the electricity supply will be tight during the peak evening period tomorrow [Thursday]," the organisation added. "This is due to a reduction in generation capacity caused by extreme temperatures across Europe."

Climate Change Poses New Challenges for UK Grid

The warning marks a reversal of traditional pressure patterns on the UK energy system. Typically, winter heating demand places greater strain on the grid.

However, warmer summer weather has led to increased use of air conditioning and fans, meaning pressure is becoming a year-round phenomenon.

The rise in consumption also coincides with reduced supply. Low wind speeds have taken many UK wind farms offline, increasing the country's reliance on domestic gas-fired power stations, nuclear plants, and costly energy imports.

According to real-time data from National Grid, wind power accounted for just 6.6% of the UK's electricity mix on Wednesday. During the day, the country's growing number of solar farms helped compensate for the drop in wind generation. But in the evening and overnight, the grid has been forced to rely heavily on fossil fuels and expensive foreign energy from neighbouring countries.

Continental Europe Also Affected

Mainland Europe is itself suffering a major heatwave, expected to intensify in the coming days. The UK depends on France for much of its emergency power supply, but France has been forced to reduce output from its large fleet of nuclear plants because nearby water sources are too warm to cool the reactors.

Neso added that the warning does not signal an imminent series of blackouts. Once buffer capacity is secured, it typically withdraws the warning, as happened during last June's heatwave.