Why Heat Waves Heighten the Risk of Blackouts

Extreme heat waves are pushing power grids to their limits globally, significantly increasing the risk of blackouts. In late June, a heat wave in France left nearly 70,000 households without power after a transformer failed under high temperatures.

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As it gets hotter, things stop working quite so well.

As the United States experienced extreme heat, federal authorities issued blackout warnings. Grid operators were authorized to instruct large energy consumers, such as data centers, to switch to backup power. This measure aims to maintain electricity supply for homes and essential services like hospitals.

Globally, power grids are struggling to cope with intense heat waves and other extreme weather events. In the US, heat-season power outages, some linked to high temperatures, have risen approximately 60% over the past decade compared to the 2000s, according to data from Climate Central. These outages pose particular dangers to children, the elderly, and individuals with chronic illnesses who lack access to cooling.

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One should expect faults to be more common at these very high temperatures.

This trend is expected to worsen as human-induced climate change leads to longer, more frequent, and more intense heat waves. Experts emphasize the urgent need for energy networks to adapt. "As it gets hotter, things stop working quite so well," said Iain Staffell, an associate professor of sustainable energy at Imperial College London. "One should expect faults to be more common at these very high temperatures."

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I think we do need to adapt the power system to cope with the changing weather.

Heat waves strain power networks in several ways. Electricity demand surges as people use air conditioners and fans. Simultaneously, infrastructure like power plants and transformers becomes vulnerable. Transmission lines expand and sag in high temperatures, increasing the risk of short circuits. "The grid operator has to reduce the amount of power that flows down these wires in the very hottest temperatures to make sure everything remains safe," Staffell explained. Thermal power plants also suffer, as extreme heat reduces the effectiveness of cooling systems in coal, gas, and nuclear facilities.

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The grid operator has to reduce the amount of power that flows down these wires in the very hottest temperatures to make sure everything remains safe.