France’s power grid strained as heatwave forces gas and nuclear plant reductions

Extreme heat has pushed French power generators to cut output across multiple fuel types. The 930 MW gas‑fired Martigues plant in southern France received a production alarm from EDF when Mediterranean sea water exceeded the 32 °C limit, bringing the unit close to a forced shutdown.

At the same time, high river temperatures have kept about 4.9 GW of nuclear capacity offline, while low water levels have removed another 2.5 GW, together representing roughly 14 % of France’s total electricity potential. The shortfall adds pressure to an already weakened grid.

The episode highlights a broader vulnerability: hydropower output drops as river flows diminish, wind turbines generate less in hot, low‑density air, and solar systems face higher demand for cooling. Climate‑driven heatwaves therefore pose a growing risk to the stability of France’s electricity supply.