Britain’s electricity grid operator has issued a fresh appeal to the energy industry for increased power generation, as the country endures its third heatwave of the year. The National Energy System Operator (Neso) forecast a tight period for electricity margins this Thursday evening, citing "extreme temperatures" across Europe as the primary cause.This marks the third such electricity margin notice from Neso this year, a measure more commonly deployed during cold winter spells when home heating demand is at its peak. However, intense heat similarly strains the electricity system by reducing the efficiency of power generation from nuclear plants, gas stations, and water cooling systems. Simultaneously, the sweltering conditions significantly boost electricity usage for fans and air conditioning as people seek relief. The notice serves as a clear signal to the electricity market, indicating the operator's desire for a greater safety cushion, or margin, between power demand and supply for a defined duration.Britain’s electricity grid operator has issued another rare summer plea for more power generation (Stefan Rousseau/PA) (PA Archive)This allows production to increase if necessary to increase capacity in the grid.Neso said it does not signal that blackouts are imminent or that there is not enough generation to meet demand.The notice is in place for between 6.30pm and 10.30pm on Thursday.On Wednesday evening, a spokesman said: “Our forecasts indicate tight electricity margins during tomorrow evening’s peak period.“This is due to extreme temperatures across Europe, reducing the availability of some generation.”Neso said it does not signal that blackouts are imminent or that there is not enough generation to meet demand. (PA Archive)Neso said it would “continue to monitor conditions closely and take any actions necessary to maintain secure electricity supplies”.The body, which is tasked with balancing the nation’s electricity supply with demand, sent callouts for more power generation twice in June.Both were cancelled ahead of time, indicating Neso was confident in supply levels for the period.Health and fire warnings have been issued this week as temperatures soar in the third heatwave of the year.The heat is expected to peak on Thursday and Friday when temperatures will “widely exceed 30C” across the UK, and some areas in England could hit 36C, according to the Met Office.