The regional drought is affecting hydropower, nuclear cooling, coal generation and fuel logistics across the Danube basin. 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.
Hydropower and thermal generation impacts along the river
In Serbia, the drought exposure includes loss of hydropower generation and reduced cooling at Kostolac. Fuel logistics are also constrained by river conditions. During July, fuel imports reached only about 25 per cent of their planned volume.
The shortfall in deliveries was linked to barge loading rates of 30–40 per cent of normal capacity. Replacement transport by road and rail increases the delivered cost of fuel. It also cannot immediately match the scale of river-based logistics.
Nuclear cooling risks at Kozloduy and Cernavodă
Operational consequences extend beyond a 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.
The depth and duration of the current event have brought cooling-water availability under closer scrutiny at Kozloduy. The same low-flow conditions are therefore relevant to both nuclear sites along the river system.
Market effects and financing assumptions for storage projects
The regional price effect is described as nonlinear. A missing megawatt of hydroelectricity during a well-supplied solar hour may have limited value, while a similar shortfall during the evening ramp can require gas-fired generation or constrained imports.
Drought can therefore widen daily price spreads even when average renewable output remains substantial. It also changes investment economics for hydro projects, including reservoir and pumped-storage schemes. Lenders are expected to require more conservative assumptions for water availability, operating head and environmental releases.
The event supports storage value but also indicates that water-dependent storage cannot be treated as immune to climate risk.
