The regional drought is simultaneously affecting hydropower, nuclear cooling, coal generation and fuel logistics. Danube discharge along the Bulgarian section was approximately 1,617–1,883 cubic metres per second on 28 July, with the gauge at Kozloduy recording an exceptionally low level.
The operational consequences extend beyond the controlled shutdown of Cernavodă Unit 1. Romania has warned that Unit 2 could also be disconnected if the river reaches its operating limits. Bulgaria’s two approximately 1 GW Kozloduy reactors are designed with a dedicated pumping station, but the depth and duration of the present event have brought cooling-water availability under closer scrutiny.
Serbia faces the broadest exposure. Besides the loss of hydropower generation and reduced cooling at Kostolac, fuel imports during July reached only about 25 per cent of their planned volume because barges were loading at 30–40 per cent of normal capacity. Replacement transport by road and rail raises the delivered cost of fuel and cannot immediately reproduce the scale of river logistics.
The regional price effect is nonlinear. A missing megawatt of hydroelectricity during a well-supplied solar hour may have limited value, but the same shortfall during the evening ramp can require gas-fired generation or constrained imports. Drought therefore magnifies the daily spread even where average renewable output remains substantial.
It also changes the economics of proposed hydro investments. Reservoir and pumped-storage projects retain considerable flexibility value, but lenders will require more conservative assumptions for water availability, operating head and environmental releases. The present event strengthens the case for storage while simultaneously demonstrating that water-dependent storage cannot be treated as immune to climate risk.
