The drought on the Danube is affecting multiple parts of the regional energy system, including hydropower, nuclear cooling, coal generation and fuel logistics. On 28 July, Danube discharge along the Bulgarian section was approximately 1,617–1,883 cubic metres per second. The gauge at Kozloduy recorded an exceptionally low level.
Nuclear cooling risks at Cernavodă and Kozloduy
Operational impacts are not limited to the controlled shutdown of Cernavodă Unit 1. Romania has warned that Cernavodă Unit 2 could also be disconnected if the river reaches its operating limits. Bulgaria’s two approximately 1 GW Kozloduy reactors use a dedicated pumping station for cooling water.
The depth and duration of the current event have brought cooling-water availability under closer scrutiny. The situation links river conditions directly to plant operational constraints for nuclear generation.
Serbia exposure across hydropower and coal-linked fuel supply
Serbia faces the broadest exposure among the countries described. In addition to reduced cooling at Kostolac, hydropower generation is affected by the drought. Fuel imports during July reached only about 25 per cent of their planned volume.
The shortfall was attributed to barges loading at 30–40 per cent of normal capacity. Replacement transport by road and rail increases delivered fuel costs and cannot immediately match the scale of river logistics.
Nonlinear power price impacts during daily demand swings
The regional price effect is described as nonlinear. A missing megawatt of hydroelectricity during a well-supplied solar hour may have limited value in that specific period. By contrast, the same shortfall during the evening ramp can require gas-fired generation or lead to constrained imports.
Drought conditions therefore magnify the daily spread even where average renewable output remains substantial.
Implications for hydro investment assumptions and storage economics
The drought also affects how proposed hydro projects are evaluated. Reservoir and pumped-storage projects retain flexibility value, but lenders will require more conservative assumptions for water availability, operating head and environmental releases. The event is presented as strengthening the case for storage.
At the same time, it demonstrates that water-dependent storage cannot be treated as immune to climate risk.
