Croatian state-owned utility HEP has advanced a planned 160 MW pumped-storage hydropower project in the Vinodol area into the environmental permitting process. The development is described as an additional potential flexibility asset for Croatia’s power system amid rising renewable penetration.
Planned reservoirs and site details
The scheme would be built in Primorje-Gorski Kotar county. It would use the existing Tribalj reservoir, located at around 60 metres above sea level, as the lower reservoir. A new upper reservoir, Razromir, is planned for the Koreni valley on the slopes of Mount Medvedjak at roughly 800 metres elevation.
Pumped-storage operating concept
The height difference between the two reservoirs would provide the hydraulic head needed for pumped-storage operation. During periods of lower prices or surplus generation, electricity would be used to pump water uphill. When demand and wholesale prices rise, the stored water would be released through turbines.
Market role amid higher solar penetration
The investment would provide HEP with an asset able to 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 and raise evening balancing needs. Pumped storage is positioned to capture intraday price spreads while also delivering balancing and system-support services.
Environmental assessment and next steps
The project has entered the environmental assessment process after HEP submitted documentation to Croatian authorities. Permitting outcomes, reservoir construction requirements, and the eventual investment cost are expected to influence how quickly the scheme can move toward execution. Unlike conventional hydropower, the operating strategy is described as being driven primarily by market conditions rather than natural water inflows.
Implications for Croatia’s flexibility needs
The project is presented as strengthening domestic flexibility as regional power-market volatility increases alongside intermittent renewable production. That shift is linked to a higher value for dispatchable storage capacity in Croatia’s market context.
