Britain grid operator calls for more power as heat strains electricity supply

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Britain grid power alert

Highlights

National Energy System Operator called on power stations to boost output as high temperatures and low wind reduce UK electricity supply margins.
UK power prices rose on Tuesday as falling wind speeds and 38C–40C temperatures strained grids, with a Met Office red alert issued for southern England and Wales.
Transport disruptions escalated, with nearly 250 UK train services—about 7% of daily journeys—cancelled as rails risk expansion and buckling in extreme heat.

Heatwave pressures evening power balance

As reported by Financial Times, the National Energy System Operator, or Neso, is asking power stations that can raise output to help stabilise supply during a period of high temperatures and low wind speeds. The operator says the notice reflects a need for a greater safety cushion between electricity demand and available supply, rather than an indication of imminent power cuts.

The warning comes as the UK Met Office issues a red alert for extreme heat, only the second such alert in its history. Low winds are cutting output from wind turbines at the same time that hotter conditions are lifting power use for air conditioning and fans.

Heat is also reducing the efficiency of key generation sources. Analysts at Montel say solar panel efficiency drops by 0.3% to 0.5% for every degree above 25C, while gas-fired plants also perform less efficiently because warmer air is less dense and makes it harder to maintain operating pressure ratios.

Transport disruption and wider market effects

Power prices are rising on Tuesday as wind speeds fall and temperatures climb across Europe, adding to the pressure on wholesale electricity markets. The Met Office alert covers parts of southern England and Wales on Wednesday and Thursday, with temperatures expected to reach 38C to 40C and potentially break June records.

The heatwave is also disrupting transport across the UK, with hundreds of train services cancelled as operators seek to avoid more severe disruption later in the day. London Northwestern says extreme heat can cause rails to expand and buckle, requiring trains to run more slowly once temperatures pass certain thresholds.

According to live figures from data aggregator trains.im cited in the report, Avanti West Coast has cancelled more than half of its services, while Northern, Great Western and South Western have also cut dozens of trains. Nearly 250 services across the UK have already been cancelled, equal to about 7% of the day’s expected journeys, and some operators are replacing non-stop trains with slower stopping services to free capacity on faster lines.

Our earlier update on natural gas highlighted prices hovering near $3.20 as the market balanced seasonal demand with comfortable inventories, alongside a large weekly storage build reported by the EIA. It also noted that hotter weather forecasts were supporting expectations for higher power-sector demand for air conditioning, while strong production and elevated storage levels continued to cap upside momentum.

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