Great Britain’s National Energy System Operator (Neso) deployed emergency measures on Wednesday to maintain electrical supply stability as a severe heatwave gripped the region. The operator secured roughly 1.7 gigawatts of imported electricity from continental Europe at a cost near £1,400 per megawatt-hour, approximately 20 times the average market price recorded in June of the previous year. This represented total expenditure of approximately £10 million for the day’s operations.
Neso had issued a margin notice on Tuesday evening indicating the need for an additional 1,900 megawatts of power to maintain normal safety margins during peak evening demand hours from 7pm to 10pm on Wednesday. The notice called upon electricity generators to provide any surplus capacity from their plants. Officials confirmed that electricity supply remained adequate and that the notice did not signal an imminent blackout risk. A Neso spokesperson attributed the emergency measures to extreme temperatures affecting Great Britain and continental Europe alongside reduced wind generation.
The extreme weather created broader strain across European energy markets, with elevated temperatures increasing demand for cooling while simultaneously reducing renewable energy generation. Nuclear power plants in France operated at reduced capacity due to high river water temperatures affecting cooling systems. The combination of rising demand and constrained supply drove electricity prices across European markets to multiyear highs.
Domestic impacts extended beyond the energy sector. The UK recorded a temperature of 35.8 degrees Celsius in West Sussex, establishing a new record for June. Train operators restricted service, numerous schools closed across southern England and Wales, and hospital appointments were cancelled. Several trade unions called for worker participation in strikes during the peak heat period, highlighting concerns about workplace conditions during the heatwave, though UK regulations establish no maximum legal temperature for workplaces.