Water scarcity in Europe: Why this causes problems for energy supply

At the end of July 2026, Hungary's only nuclear power plant, Paks, had to be completely shut down for the first time since it was commissioned in 1982. Cause: Water scarcity in Europe. The Danube water level at Budapest fell to a historic low of just 31 centimeters, creating problems for the country's entire energy supply. Around 2,000 megawatts of generation capacity are thus missing from the Hungarian grid, half of which is otherwise powered by Paks. Hungary is not an isolated case: from France to Bulgaria, the summer of 2026 shows that power plants with river water cooling are reaching their physical limits—and these limits will be reached more frequently in the future.

Overview: Which nuclear power plants are currently affected by water shortages

Table – As of August 3/4, 2026

(Sources: Operator data Axpo/EDF/dpa, NEI Magazine, as of early August 2026)

Coal, gas, and run-of-river power plants are also coming under pressure

The water shortage in Europe and the cooling water problem are not unique to nuclear energy – they affect every thermal power plant that uses river water for condenser cooling. Coal and gas-fired power plants also depend on rivers having sufficient water that is not too warm: at the end of July, the Serbian coal-fired power plant Kostolac had to reduce its output because the cooling water intake failed due to low water levels in the Danube.

Even run-of-river power plants, which normally do not face cooling water issues, are suffering from the declining flow: Eiserne Tor 1 on the Danube—the region’s largest run-of-river power plant at 2,280 MW—is currently generating only about one-fifth of its rated capacity. The Danube’s flow rate at the Romanian-Serbian border stood at just 1,700 m³/s at the end of July—compared to the usual level of around 4,700 m³/s. Hydropower generation in Bulgaria plummeted by nearly 45 %.

The message: Anyone who believes that switching from nuclear to coal or gas power will solve the cooling water problem is mistaken. The problem does not lie in the type of fuel, but in the thermal power plant principle itself.

Water scarcity in Europe is more than a summer phenomenon

Power plants with river water cooling are vulnerable for two reasons. If the water level drops, there is simply a lack of cooling water. If the water temperature rises at the same time, many facilities are not even allowed to start up for environmental protection reasons—even if technically enough water were available, the heated return water would further heat up the river and endanger ecosystems. In France, for example, RTE applies a fixed river water temperature limit of 28 °C.

According to the World Meteorological Organization, Europe is warming more than twice as fast as the global average. Summers like 2026 are thus not becoming an exception, but a blueprint: power plants whose availability depends on river levels and temperatures tend to lose output precisely when demand—such as from air conditioning—is greatest.

In general, extreme heat waves put pressure on the power supply and grids across Europe. Read more in our article: When Heat Brings the Grid to Its Knees: The 2026 Heat Wave and Its Impact on the European Electricity Market

Germany: The Federal Network Agency is upgrading

Germany is not affected by the current shutdowns and, according to the Federal Network Agency, is still considered the country with the most stable power grid in Europe. Nevertheless, the authority is currently preemptively building a digital “Electricity Security Platform” (SiPlaS) as a counterpart to the gas security platform that has existed since 2022. It is to be operated by transmission system operator Amprion. In an emergency, energy-intensive major consumers with an annual electricity demand of 8 GWh or more are to be asked to reduce consumption with a lead time of 24 hours to three days—if a company fails to comply, the Federal Network Agency can have the power supply cut off.

What the summer of 2026 & water scarcity in Europe show for the energy transition

The current summer makes a structural problem visible. Generation capacity that is linked to river water levels and temperatures tends to fail precisely when power consumption is high. Unlike rigid large-scale power plants, battery storage systems are available independently of cooling water and weather—they can cushion short-term generation gaps and break peak loads without themselves being weather-dependent. For operators and investors, flexibility is thus increasingly becoming an independent security factor in energy supply—not just an instrument for revenue optimization.

Frequently Asked Questions