South-east Europe’s power systems face a shortage of long-duration flexibility, even as battery storage is used to capture short-term market volatility. In this context, pumped-storage hydropower projects including Đerdap 3, Čebren and Bistrica have returned to regional energy and trading discussions. The facilities are positioned as more than grid-security investments in market participation terms.
Regional system conditions remain exposed to hydrological variability, coal plant availability, import dependence and transmission constraints. Solar capacity is expanding across the region, but solar-dominated generation requires storage that goes beyond the midday-to-evening balancing window. Wind output can shift for several consecutive days, and dry years can increase reliance on imports.
Flexibility requirements shaped by renewables and system constraints
Pumped-storage hydropower is described as providing a deeper flexibility layer than conventional lithium-ion battery systems under these operating conditions. The longer duration of pumped storage is linked to its ability to cover multi-hour and multi-day periods. This includes use cases tied to renewable generation performance during weaker output periods.
Battery storage is referenced as a tool for short-term volatility capture, while long-duration needs remain unmet in the region. The gap is framed around the requirement for storage beyond shorter balancing cycles. Hydrological conditions, coal availability, import flows and transmission limits are cited as factors that keep systems vulnerable.
Đerdap 3, Čebren and Bistrica in regional development plans
Serbia’s Đerdap 3 is described as the most strategically positioned project in the region. The site would be located on the Danube upstream from Đerdap 1, with integration into a major Balkan hydroelectric corridor. Romania has been evaluating the project, and unofficial discussions have included possible participation by Hidroelectrica.
A storage facility at the Đerdap 3 location is expected to affect power price spreads and trading opportunities across Serbia, Romania, Hungary and Bulgaria. North Macedonia’s Čebren is presented as significant within a smaller national market. Proposed capacity for Čebren ranges from 333 MW to 458 MW, with annual electricity generation estimated at 1–1.2 TWh.
The Čebren project is described as potentially shifting North Macedonia from a market primarily exposed to imports toward providing regional flexibility services. Serbia’s Bistrica project includes planned reversible turbine units. Together, the three projects are referenced as strengthening the region’s flexibility portfolio.
Pumped storage revenue streams and operational characteristics
Pumped-storage assets are described as creating multiple revenue streams for energy traders. They can buy electricity during low-price periods and sell during peak-price hours. Traders can also provide balancing services and hedge renewable generation underperformance.
The same assets are also linked to capacity adequacy requirements and firming products for long-term PPAs. Operationally, pumped storage is cited as having significantly longer lifetimes and greater storage depth than most battery technologies currently deployed in the market.
Permitting, water approvals and financing as key execution hurdles
The main obstacle remains financing and project execution for pumped-storage developments. Such projects require complex permitting procedures, water-use approvals and extensive civil engineering works. Investment payback periods are also described as long.
Despite these constraints, the market case is presented as increasingly difficult to ignore in relation to renewable expansion limits without sufficient long-duration storage capacity. For regional trading desks, pumped hydro is referenced as likely to become one of the most valuable flexibility assets in the coming energy transition .
