Croatian state-owned utility HEP has advanced a planned 160 MW pumped-storage hydropower project in the Vinodol area into the environmental permitting stage. The move adds another potential flexibility asset for Croatia’s power system as renewable penetration rises. The project is now part of the environmental assessment process following documentation submission to Croatian authorities.
Site layout and reservoir elevations
The scheme would be developed in Primorje-Gorski Kotar county. It would use the existing Tribalj reservoir as the lower reservoir, at around 60 metres above sea level. A new upper reservoir, Razromir, would be built in the Koreni valley on the slopes of Mount Medvedjak at roughly 800 metres elevation.
Pumped-storage operation linked to market conditions
The height difference between the two reservoirs would create the hydraulic head needed for pumped-storage operation. During periods of lower prices or surplus generation, electricity would be used to pump water uphill. The stored water would then be released through turbines when demand and wholesale prices rise.
The investment would provide an asset that can respond directly to increasingly volatile hourly electricity prices. Croatia and neighbouring Southeast Europe markets are adding substantial solar capacity, which is expected to increase midday oversupply periods and raise evening balancing requirements. Pumped storage can capture that intraday price spread while also supporting balancing and system services.
Environmental assessment and project timeline factors
The project has entered environmental assessment after HEP submitted documentation to Croatian authorities. Permitting outcomes, reservoir construction requirements, and the eventual investment cost are expected to determine how quickly the scheme can progress toward execution.
For Croatia, the project is positioned as a way to strengthen domestic flexibility amid regional power-market volatility and intermittent renewable generation.
