Climate change causes nuclear, coal plant shutdowns

Climate change, by warming water and reducing river flows, has caused production losses at several nuclear and coal-fired power plants in the United States and Europe in recent years and will lead to more power disruptions in the future, researchers report.

The Browns Ferry Nuclear Plant in Alabama, for example, had to shut down more than once last summer because the Tennessee River's water was too warm to use it for cooling. The likelihood of extreme drops in power generation from total or partial plant shutdowns will triple in the next 50 years, according to a study published this week in Nature Climate Change.

"This study suggests that our reliance on thermal cooling is something that we're going to have to revisit," co-author Dennis Lettenmaier, a University of Washington professor of civil and environmental engineering, said in announcing the findings.

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Power from thermoelectric plants, which provide more than 90% of electricity in the U.S. and three-quarters in Europe, will decrease 4% to 16% in the U.S. and 6% to 19% in Europe due to lack of cooling water between 2031 and 2060, the authors project.

These plants use nuclear or fossil fuels to heat water into steam that turns a turbine. While much of this water is "recycled," they rely on consistent volumes of water, at a particular temperature, to prevent the turbines from overheating.

"The worst-case scenarios in the Southeast come from heat waves where you need the power for air conditioning," Lettenmaier said. "If you have really high power demand and the river temperature's too high so you need to shut your power plant down, you have a problem."

Discharging water at elevated temperatures causes other problems, the study says. "Another growing concern is the environmental impact of increasing water temperatures on river ecosystems, affecting, for example, life cycles of aquatic organisms," said first author Michelle van Vliet, a doctoral student at the Wageningen University and Research Centre in the Netherlands.

The authors say long-term adaptation strategies include placing new plants near saltwater, thus reducing their reliance on freshwater sources, or switching to gas-fired alternatives.