Europe's heatwaves strain nuclear, hydropower, driving electricity costs

A series of blistering heat waves has weakened some of Europe’s most historically reliable sources of electricity, forcing the continent to lean more heavily on imported fossil fuels and variable renewable energy. 

France’s river-cooled nuclear plants have suffered a record amount of heat-related outages this summer. Hungary’s only nuclear station faces shutdown as river levels fall. And hydroelectric plants in the Alps and Nordic region — a crucial source of on-demand, low-carbon power — have been hobbled by hot, dry weather. With more scorching days forecast for August, the disruptions are poised to push power prices even higher, leaving Europeans facing steeper electricity bills just to keep cool.

 

 

The heat-related strains coincide with a surge in natural gas and coal prices after the collapse of the US-Iran ceasefire once again sharply curtailed traffic through the Strait of Hormuz. It’s an echo of 2022, when Russia slashed gas supplies to Europe ahead of its invasion of Ukraine, sending energy prices to astronomical levels. The crisis was compounded by an extensive maintenance and repair program that sidelined a large part of France’s nuclear fleet and by historically low hydroelectric output.

 

France has lost over 3.7 terawatt-hours of nuclear power to temperature restrictions during June and July alone, more than double the previous full-summer record set in 2018, according to ICIS data. While overall generation has remained broadly in line with recent years, output has fallen sharply during periods of extreme heat, reducing supplies as electricity demand for air conditioning peaks.

 

Many of France’s nuclear plants rely on river water for cooling before discharging the warmer water back into the river. Environmental regulations limit those discharges when temperatures are already high, forcing reactors to reduce output. Électricité de France Chief Executive Officer Bernard Fontana said the Chooz 1 reactor on the Meuse River will be halted from Saturday to comply with an intergovernmental agreement with Belgium that requires a minimum river flow. Chooz 2 has already been offline since mid-July, he said. One reactor at the Cattenom nuclear power station on the Moselle River near Luxembourg is also scheduled to shut from Saturday.

 

“France is pulling prices up in neighboring markets,” said Matthew Jones, head of power analytics at ICIS. “We’re going into another heat wave potentially and there could be several more. Given what existing heat waves have done, there are fears in the market that it will only get worse.”

 

The situation may prove even more serious — and longer-lasting — in the Alps and the Nordic region, where hydroelectric reservoirs are running dry. Unless they are replenished before winter, Europe could enter its peak heating season without one of its most important sources of flexible electricity, at a time when gas storage is lower than usual.

 

In Norway, by far Europe’s biggest producer of hydropower, reservoirs are filling up at about the lowest rate in the last 20 years, according to Katinka Bogaard, managing director at Volt Power Analytics in Oslo. A combination of factors is to blame: below-average snowfall last winter; an unusually warm spring and summer that already melted limited snowpack; and persistently dry weather that has left too little runoff to replenish reservoirs. Southern Norway has also exported 3.8 TWh this year to Germany, England, Denmark and the Netherlands, according to data from Norwegian grid operator Statnett.

 

“We’re paying winter prices now, which is new,” Bogaard said in an interview. “If we get the most extreme amount of precipitation, we can bring the levels close to normal. But that’s what we need to get back to a normal situation.”

 

Europe’s increasingly interconnected power grid is meant to cushion local shocks by allowing electricity to flow from regions with a surplus to those facing shortages. This year, for example, Norway has imported cheap midday solar power from Germany when output there exceeds demand. But as climate-driven disruptions become more widespread, that buffer weakens. When multiple countries face shortages at the same time, power prices can rise across the region instead of being contained.

 

“Regardless of what is happening in the Middle East, these big hydro deficits in Norway will keep prices higher,” said Christopher Kurish, portfolio manager at power trading firm Mind Energy in Denmark. “Reservoirs probably won’t get filled enough come winter time. So it’s very worrisome for the market.”