Abstract
From the confluence of the Lech River with the Danube to the Danube Delta, installed electricity generation capacities of approximately 16.983~GW directly use water from the Danube, namely: 6096.34~MW hydro, 4657.7~MW gas-fired (including one combined heat and power PP fueled primarily by natural gas and hydrogen), 1007~MW coal-fired and 5222~MW nuclear power plants (PPs). As is well known, hydro PPs use water to spin turbines, gas-fired PPs use water to cool and generate steam, coal-fired PPs use water to generate steam, cool equipment, and manage waste, while nuclear PPs use water to cool and generate steam, as well as to moderate fast-moving neutrons. If there is a record-low water level in the river from which the PPs are supplied with water, then the execution of all the processes may be jeopardized and then suspended. This can ultimately cause several successive and widespread electricity blackouts, or a total blackout. Such a water level in the Danube occurred due to a drought and heat waves during the summer of 2026 and endangered the operation of a number of existing PPs along the Danube and its tributaries. Accordingly, this editorial provides an overview of PPs that directly use water from the Danube, as well as some larger PPs that use water from four other rivers of the Danube basin. The overview includes the name, location, installed capacity, energy source and type of PPs, explains why the water in the Danube reached a record-low level in 2026 and highlights some events that could have caused electricity blackouts.