Heatwaves Impact on Power Generation: Nuclear, Gas, Wind, and Solar

Extreme heatwaves are becoming more common and intense due to climate change, impacting various sources of power generation worldwide. As temperatures soar, nuclear reactors shut down, gas plants' efficiency falls, wind speeds drop, and electricity networks sag. The increased demand for electricity during heatwaves drives up power prices, putting a premium on electricity. ## Nuclear Power Nuclear power plants are particularly vulnerable to heatwaves, especially those using river water for cooling. In France, around 70% of electricity is generated by nuclear power, making it susceptible to heatwave impacts. During the July 2026 heatwave, three of France's 57 nuclear reactors had to shut down, and generation was reduced at another seven, causing a nearly 9% dip in power production. This phenomenon is well-documented, with France experiencing reductions in nuclear generation due to heatwaves in 2003, 2006, 2015, 2018, 2019, 2022, and 2025. Nuclear power plants use fission to generate heat, which is used to create steam. This steam spins the blades of a turbine connected to a generator to create electricity. However, when water temperatures rise due to a heatwave, their cooling capacity is reduced, and the overall efficiency of the nuclear power station is affected. Similarly, if there is less water available due to drought, they cannot be cooled as effectively. Michael Tadrous, a researcher at McMaster University's DeGroote School of Business in Canada, notes that the impact of heatwaves on nuclear power is real but smaller than many headlines suggest. He adds that the effect of heat is gradual, and warmer intake water makes a reactor slightly less efficient. Even an extreme 15C rise in cooling-water temperature would cost a large reactor only about 6% of its output. ## Gas Power Gas power plants have a reputation for being reliable and able to switch on at any moment. However, as a type of thermal generation, they are subject to many of the same stresses during heatwaves as nuclear power. The efficiency of gas power plants drops as temperatures rise, with a 13% reduction in capacity and 7% reduction in efficiency at 40C compared to 20C. Dr. Iain Staffell, associate professor in sustainable energy at Imperial College London, notes that simple gas turbines are hit harder, with their power output falling by about 10% per 10C. Several types of gas power plants require cooling as part of their process, including gas steam and combined cycle turbines (CCGTs). They usually rely on cooling systems, which can be affected by heatwaves. Dr. Staffell notes that the transmission system struggles more than electricity generation during high temperatures, with power line capacity falling by up to 16% for a 10C rise in temperature. ## Wind and Solar Power While wind and solar power are often criticized for being 'intermittent,' they are not immune to the effects of heatwaves. Wind speeds drop during heatwaves, reducing the output of wind turbines. Solar panels can also be affected by high temperatures, which can reduce their efficiency. However, the impact of heatwaves on wind and solar power is generally less significant than on nuclear and gas power. ## Adaptations and Challenges Governments and nuclear companies are looking at a range of solutions to adapt to heatwaves, including additional cooling towers for nuclear power plants. The nuclear power industry is already adapting to heatwaves that are more frequent and more intense, with utilities upgrading cooling systems, refining operating practices, and scheduling maintenance around periods of extreme heat. However, there remain challenges for adapting nuclear power and the wider electricity systems in which it sits to heatwaves. The economic prioritization and timely implementation of these adaptations are crucial to minimizing the impact on both energy security and costs.