Without nuclear power there is no security of supply

The lack of water is also affecting our electricity production. Dozens of river-powered plants in Switzerland are currently shut down or operating at reduced capacity. In September, the Axpo power plant in Rheinau reached only 43 percent of its ten-year average. Alpiq’s Aare power plants are producing about 30 percent less than usual, and the Höngg power plant on the Limmat has shut down completely. Normally, run-of-river hydropower supplies 10 to 15 percent of our electricity in the fall; currently, it accounts for only a fraction of that. Reservoir levels this summer were at their lowest in 20 years. This has compromised a key pillar of Switzerland’s winter electricity production.

Hydropower remains the backbone of our electricity supply. It provides a good half of Switzerland’s electricity. But this year, its Achilles’ heel has become apparent: it depends on the weather. And far more than just electricity depends on rivers and reservoirs—namely, drinking water, irrigation, minimum flow requirements, cooling, and navigation. These conflicts over water use will increase. Glaciologists predict that glacial meltwater—which acts as a buffer during dry periods—will have disappeared in a few decades.

This is exactly where nuclear power shows its strength. It generates electricity regardless of precipitation, runoff, or hours of sunshine—and especially when we need it most: in the winter. Since the decommissioning of Mühleberg, it has supplied an average of about 12.4 TWh during the winter months. Solar power plants generated 2.3 TWh last winter. Nuclear fuel is also compact and can be stored for years. A nuclear power plant does not depend on ships sailing down the Rhine every week, even when the river’s water level is low.

And what about the shutdowns at Beznau during the hot summer? They actually confirm the resilience of nuclear power. Beznau was not taken offline because the plant couldn’t cope with the heat. ENSI has maintained for years that heat waves do not pose a safety risk to Swiss nuclear power plants. The reason is a water protection regulation that applies only to Beznau: After the cooling water is discharged, the temperature of the Aare River must not exceed 25 degrees. Gösgen and Leibstadt, with their cooling towers, were not affected. Furthermore, the annual inspections of nuclear power plants take place in the summer anyway, when electricity is abundant. During this period, solar power stepped in and supplied about a quarter of the electricity.

Security of supply is never a matter of finding the one "right" technology. It is a matter of finding the right portfolio. Photovoltaics, together with hydropower, carry the load during the summer months. Nuclear power provides a reliable foundation when the days are short and river levels are low. In winter, it can then fully leverage its strengths. Anyone who wants to do without it should first show what will fill the gap during the next dry summer and cold winter. We should not rely solely on imports from neighboring countries that are themselves struggling with low water levels and strained energy markets, even if energy trade with Europe is important. That is why we must operate our existing nuclear power plants as long as they are safe and keep the option for new ones open. It would be nothing less than a rational decision.