Serbia Targets 2027 Tender for 660 MW Bistrica Pumped-Storage Project

Serbia’s state-owned electricity utility Elektroprivreda Srbije (EPS) plans to launch a construction tender in 2027 for the 660 MW Bistrica pumped-storage hydropower plant, a major infrastructure project intended to support renewable energy integration and improve electricity-system flexibility.

EPS said preparations had intensified, with approximately 250 applications for permits, conditions and approvals submitted over the previous six months. The utility expects to obtain the main construction permit and initiate the principal procurement procedure in 2027. Financing discussions with the Japan International Cooperation Agency (JICA) are also expected to advance towards an agreement during the year.

The project is designed to support the integration of approximately 1,500 MW of additional renewable generation capacity. The construction contract has not been awarded, proposed financing has not reached financial close, and significant technical, environmental and implementation requirements remain.

Pumped Storage to Support Renewable Integration

Bistrica is planned as a large-scale electricity-storage facility that would use electricity to pump water into an upper reservoir during periods of lower demand or surplus production. When consumption and electricity prices rise, the stored water would pass through turbines to generate electricity. The system would allow EPS to shift electricity use and generation between different hours. Its commercial value would depend on the difference between electricity prices during pumping and generation, adjusted for conversion losses, operating costs and other system requirements.

The facility could also provide reserves, frequency control and grid-stability services, depending on its technical design and applicable market arrangements.

As wind and solar capacity expands, Serbia faces a growing need for flexible electricity resources. Renewable generation varies with weather conditions, potentially depressing daytime prices during strong solar output while increasing the value of dispatchable electricity during evening peaks. Insufficient flexibility can contribute to higher balancing costs, renewable curtailment and greater reliance on imports or thermal generation. Bistrica’s eventual contribution will depend on EPS’s operating strategy and the transmission-system requirements established for the plant.

Electricity Price Spreads Will Shape Commercial Returns

The project’s financial case extends beyond its installed generation capacity. Electricity markets across Southeast Europe experience hourly price differences influenced by renewable output, thermal generation availability, interconnector constraints and consumption patterns.

Pumped storage can use these differences by consuming electricity during lower-priced periods and generating during higher-priced hours. However, the gross price spread does not equal operating profit because pumping requires more electricity than the facility subsequently generates.

EPS’s financial assessment will need to account for energy trading, balancing and ancillary services, potential system-security benefits and interactions with existing hydropower and thermal assets. It must also distinguish revenues available to the utility from wider economic benefits to Serbia’s electricity system, avoiding double-counting the same flexibility benefits.

The investment must recover substantial construction expenditure over a long operating life. Its returns will depend on electricity-price volatility, renewable deployment, market integration and competing flexibility resources. Greater renewable generation could increase demand for storage, while narrower price spreads or additional competing capacity could weaken returns.

JICA Financing and Project Bankability

The expected involvement of JICA could provide access to long-term development financing suitable for a major infrastructure asset. However, financing discussions do not constitute a signed loan agreement.

The final financing structure, interest terms, repayment period, borrower obligations and any sovereign-support arrangements remain important elements of the project’s bankability. Construction risks include geological conditions, underground works, excavation, tunnelling, water infrastructure and access roads. Delays could increase interest costs during construction and postpone commercial operations. Revenue projections must also be tested against different electricity-market scenarios rather than relying on a single price forecast.

EPS will need to demonstrate that the project’s commercial and system benefits justify its full lifecycle costs, including debt service, maintenance and periodic equipment replacement.

Permitting and Environmental Preparation

The approximately 250 permit-related applications submitted over six months indicate substantial administrative and technical preparation, but do not establish that all approvals have been secured or that the project is ready for construction. Development requires detailed geological, geotechnical, hydrological and environmental investigations. The design must address reservoir stability, water conveyance, underground structures, turbines, pumps, electrical equipment and grid connections.

Unanticipated geological conditions could require design changes, additional support systems or different excavation methods, affecting both costs and schedules. Environmental requirements also cover potential effects on land use, habitats, water resources and local communities.

Land acquisition and property rights could influence the construction timetable. Environmental and social obligations must be identified, costed and incorporated into the implementation plan, particularly as international financiers assess project compliance. The quality and completion of these preparatory studies will be important in determining whether EPS can meet its planned 2027 procurement schedule.

Contracting Strategy Will Influence Delivery Risks

Bistrica will require coordination across civil engineering, hydro-mechanical equipment, electrical systems, grid infrastructure and operational controls. EPS will need to determine how responsibilities are allocated between contractors. A single engineering, procurement and construction contract could concentrate delivery responsibility but may include substantial pricing and risk premiums. Separate civil, electro-mechanical and electrical packages could offer procurement flexibility while increasing interface risks.

Underground works, water systems, turbines, generators and grid connections must be completed and commissioned in sequence. Delays in one package could affect the readiness of the entire plant. The contract strategy will need clear performance requirements, completion milestones, testing procedures and remedies for non-performance. Independent owner’s engineering and construction supervision would support monitoring of technical compliance, design changes, contractor performance and commissioning readiness.

Claims, variations and extensions of time will also require rigorous management. Geological risks and unclear allocation of responsibilities can lead to disputes on hydropower projects, making an executable construction framework important before major commitments are made.

Transmission Connections Must Match Plant Development

Bistrica’s value will depend on its ability to absorb and deliver substantial electricity volumes when required. The grid connection must therefore accommodate both pumping demand and generation output.

Technical requirements may include voltage control, protection coordination, system-stability studies, communications infrastructure and dispatch interfaces. Coordination with Serbia’s transmission-system operator, Elektromreža Srbije, will be necessary.

Any required grid reinforcement must be aligned with construction and commissioning. If network constraints prevent a mechanically completed plant from operating at its intended capacity, its commercial value could be reduced. The planned support for 1,500 MW of additional renewable generation does not represent a guaranteed one-to-one relationship between storage capacity and new renewable installations. Actual integration will depend on generation locations, network constraints, production profiles and system operating conditions.

Regional Electricity Markets Affect the Investment Case

Serbia is interconnected with neighbouring electricity markets, including Hungary, Romania, Bulgaria, Bosnia and Herzegovina, Montenegro and North Macedonia. Regional prices reflect cross-border capacity, generation availability and market-coupling arrangements.

Pumped storage could allow EPS to increase electricity demand during low-price periods and generate power when prices rise, potentially reducing import requirements or creating export opportunities. The benefits would depend on the availability and cost of cross-border transmission capacity.

Congestion can limit the use of regional price differences, while deeper market integration may change the timing and size of price spreads. EPS’s investment assessment will therefore need to include regional price modelling, congestion assumptions and balancing-market developments. Bistrica’s economics will be shaped by the wider Southeast European electricity market over the plant’s operating life, rather than by domestic generation conditions alone.

2027 Procurement Will Test Project Readiness

The planned construction tender will be a key milestone, but its timing will depend on the maturity of technical documentation and financing arrangements. Procurement launched before major uncertainties are resolved could lead to higher contractor contingencies, later design changes and disputes, while prolonged preparation could delay the availability of storage capacity.

EPS will need to coordinate procurement milestones with verified progress on geological investigations, environmental approvals, land requirements, grid studies and financing conditions.

The project will also need to be assessed alongside other flexibility options, including battery storage, flexible thermal generation, demand response and transmission investment. These technologies provide different capabilities: pumped storage can shift large amounts of electricity over extended periods, while batteries may be deployed more quickly and provide highly responsive short-duration services. Bistrica’s transition from permitting to procurement in 2027 will test whether EPS can secure financing, manage construction complexity and establish sustainable operating economics for the planned 660 MW electricity-storage facility.