Croatian state-owned utility HEP has moved a planned 160 MW pumped-storage hydropower project in the Vinodol area into environmental permitting, adding another potential flexibility asset to a Croatian electricity system facing rising renewable penetration.
The project would be developed in Primorje-Gorski Kotar county and use the existing Tribalj reservoir, located at around 60 metres above sea level, as its lower reservoir. A new upper reservoir, Razromir, would be constructed in the Koreni valley on the slopes of Mount Medvedjak at roughly 800 metres elevation.
The large height difference between the two reservoirs would provide the hydraulic head required for pumped-storage operation. Electricity would be used to pump water uphill during periods of lower prices or surplus generation, with the stored water subsequently released through turbines when demand and wholesale prices rise.
The investment would give HEP an asset capable of responding directly to increasingly volatile hourly electricity prices. Croatia and neighbouring SEE markets are adding substantial solar capacity, creating more frequent periods of midday oversupply and greater evening balancing requirements.
Pumped storage can capture that intraday spread while also providing balancing and system-support services. Unlike conventional hydropower, its operating strategy is driven primarily by market conditions rather than natural water inflows.
The project has now entered the environmental assessment process after HEP submitted documentation to the Croatian authorities. Permitting, reservoir construction requirements and the eventual investment cost will determine the pace at which the scheme can move towards execution.
For Croatia, the project would strengthen domestic flexibility at a time when regional power-market volatility and intermittent renewable production are increasing the value of dispatchable storage capacity.
