Other reactors in the country may have to cut output because temperatures in the Rhône and Garonne rivers are too high. In Iraq, supply to most of the country went down last week as millions of pilgrims descended on the city of Karbala for the Arba’in festival, spiking grid demand for fans and air-conditioners as the mercury rose above 40° Celsius.

Even back-up equipment struggles in such conditions: electricity went out and play was suspended at the Cincinnati Open tennis tournament last week after an on-site generator apparently overheated.

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Power that goes out when we most need it should infuriate but not surprise us. Most of our infrastructure is designed to perform within specific temperature ranges that the global climate is leaving behind. More and more of it is likely to start breaking as heatwaves become more intense and widespread. 

That’s particularly the case with thermal generators, which use the heat of burning fuels or atomic decay to spin turbines and create electricity. Such plants need to dump excess heat, but this gets harder as the air and water outside warm up. The result is decreasing efficiency and overheating, forcing plants to burn more fuel for the same output or halt operations. 

The probability that a coal generator will have a forced outage goes up by 3.2 percentage points during heatwaves, while gas and nuclear are respectively 1.3 and 1 percentage points more likely to suffer an unplanned failure, according to a recent study by researchers in Sweden and Italy. Separately, Iraqi researchers found that a gas plant lost about 21% of its generation potential as the temperature rose from 25° to 50° Celsius.

Drought, which commonly occurs alongside heatwaves, makes the problem worse. Most thermal generators cool themselves by heating up water, whether it’s in the sea, rivers or cooling towers. Cool water, like cool air, gets less abundant as the temperature rises.

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India has lost 19 days’ worth of coal electricity since 2014 because water shortages have forced shutdowns, Reuters reported recently. In many areas, residents depend on tanker trucks and ever-deeper boreholes because generators are using up all of the surface water. Power stations may put more pressure on supplies of water between now and 2050 than the drinking water needs of its population, according to government forecasts. 

Conventional generators aren’t the only ones to suffer. As anyone who’s sat through a still and humid summer day would recognize, wind speeds often plummet in hot weather. Since the early 1980s, the area of the globe affected by such conditions has increased by 6.3% every decade—to the point that about 60% of the planet is now at risk. In Australia, Siberia and Europe, the availability of wind can now decline by 30% to 50% during heatwaves relative to what it would be in normal years—though a few areas, such as the northern US, east Africa, the Amazon and western China experience the opposite effect.

Even if we can solve the problem of generating energy, getting it to consumers presents challenges. Transmission cables and transformers heat up as electrons travel through their wires and rising air temperatures make such components more susceptible to failure—especially as they’re typically working harder on such days due to all the air-conditioners and fans running.

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It’s not just people who need relief from the heat. About a third of electricity consumption from data centres comes from heating and cooling to maintain stable temperatures on-site. That demand rises along with the mercury and is becoming more pressing with the spread of artificial intelligence and cryptocurrencies. A heatwave in 2022 caused chaos at two London hospitals when their server racks shut down, scrambling the IT systems they depend on to process medical data.

The rising dominance of solar panels and lithium-ion batteries, which tend to be more resilient than thermal generators and wind during heatwaves, will offer some respite. It still may not be enough. Most of our industrial civilization, built from the energy riches unleashed by coal, oil and gas, depends on a moderate climate that their carbon emissions are throwing into disorder. The damage caused by fossil technology is going to be with us long after we have switched to cleaner ways of generating power.   ©Bloomberg

The author is a Bloomberg Opinion columnist covering climate change and energy.