Serbia’s planned Đerdap 3 pumped-storage hydropower plant has entered a new development phase after six U.S. companies submitted expressions of interest for participation in the project’s development and construction. The public call, issued through the U.S. Embassy in Belgrade, closed on 25 June 2026, with qualification reviews now under way.
- Pumped Storage Project Targets Greater Grid Flexibility
- Investment Scale Requires Detailed Financial Structure
- Development Phase Includes Feasibility and Environmental Studies
- Romania Coordination Remains Key Project Requirement
- Environmental Permitting Will Influence Investment Decisions
- Storage Competition Expands as Battery Capacity Grows
- U.S. Participation Expands Strategic Dimension
- EPS Faces Strategic Infrastructure Decision
The project is planned with an indicative installed capacity of 2,400 MW and an estimated investment value of approximately €2.63 billion to €3 billion, positioning it among the largest planned energy-storage facilities in Southeast Europe.
The initiative is being developed within the framework of Serbia–U.S. strategic energy cooperation. The agreement underpinning the cooperation framework was signed in Washington on 18 September 2024 by Serbian Foreign Minister Marko Đurić and U.S. Under Secretary Jose W. Fernandez, with the project identified as a potential platform for cleaner energy, long-term supply security and expanded bilateral cooperation.
Pumped Storage Project Targets Greater Grid Flexibility
Đerdap 3 is being considered at a time when Serbia’s electricity system is undergoing structural changes. The country remains significantly dependent on coal generation, while renewable energy capacity is expanding and the power grid requires additional flexibility.
Serbia’s 2024 integrated energy and climate plan sets a target of a 33.6% renewable share in gross final energy consumption by 2030, including a 45.2% renewable share in electricity generation.
Evailable energy data indicate a gap between policy objectives and current generation patterns. Ember’s country data for 2025 show Serbia produced 28% of electricity from low-carbon sources, while Serbian reporting based on Ember’s 2024 figures placed coal’s share of electricity generation at 62.9%. The difference between future renewable targets and the existing power mix has increased interest in large-scale storage solutions capable of balancing variable renewable production.
According to the project concept developed by Elektroprivreda Srbije (EPS), Đerdap 3 would operate as a reversible pumped-storage facility rather than a conventional hydropower plant.
The planned location is at the 1,007th kilometre of the Danube, using water from Đerdap Lake at an elevation of approximately 68 metres. During periods of excess electricity supply, water would be pumped into planned upper reservoirs Pesača and Brodica, while during peak demand periods it would flow back through turbines to generate electricity. EPS’s concept includes a three-stage development plan with total reservoir water volume of 578 million cubic metres, an energy equivalent of approximately 484 GWh in the final phase and total installed capacity of 2,400 MW.
Investment Scale Requires Detailed Financial Structure
The estimated capital requirement places Đerdap 3 among Serbia’s largest planned infrastructure investments. At an investment value of €2.63 billion, the project would represent approximately €1.1 million per MW of installed capacity if the full 2,400 MW configuration is completed. At €3 billion, the figure would rise to around €1.25 million per MW, before accounting for financing costs, contingencies, grid connections, environmental measures, land requirements, access infrastructure, tunnels, electromechanical equipment and potential cross-border considerations. The project would compete for capital alongside other major energy priorities, including RHE Bistrica, transmission system upgrades, renewable energy projects, battery storage development, coal transition costs and restructuring requirements at EPS.
The economic justification for Đerdap 3 depends on its ability to provide broader electricity-system value beyond domestic peak demand management. A large pumped-storage facility could potentially generate value through electricity market arbitrage, capacity services, renewable balancing, ancillary services, congestion management and reserve availability across the Southeast European market.
Development Phase Includes Feasibility and Environmental Studies
The current process remains at an early development stage despite the project’s large capacity and investment estimates. The public-call documentation foresees further work to determine the final project configuration, including the number of units, installed capacity and reservoir dimensions through feasibility studies and front-end engineering design (FEED) documentation.
The initial development package is expected to include conceptual design, preliminary design with feasibility studies, geotechnical and hydrological analyses, construction planning, environmental impact assessment (EIA) and environmental and social impact assessment (ESIA) studies. The FEED phase is expected to last approximately 36 months, after which the selected participant could potentially proceed toward construction subject to a final agreement.
The project is therefore currently being considered as a strategic development option rather than a ready-to-build facility. Possible phased implementation, including an initial 600 MW to 1,000 MW configuration, could provide a more financeable approach, while the full 2,400 MW development would require a stronger regional market case.
Romania Coordination Remains Key Project Requirement
The international nature of the Danube creates additional requirements for project development. The existing Đerdap 1 and Đerdap 2 hydropower systems are shared Serbian-Romanian assets on the Danube, meaning Romania has a direct interest in any project that could influence river flows, navigation conditions or electricity production at the Iron Gates complex.
Romania has moved toward discussions with Serbia regarding a memorandum of understanding for information exchange on Đerdap 3. Romanian authorities are seeking assurances that the project will not negatively affect production at Iron Gates I and Iron Gates II or navigation on the Danube.
Because pumped-storage operations involve changing water movement patterns, technical studies must demonstrate that pumping and generation cycles will not disrupt existing hydropower operations or create downstream impacts. Any future financing process would require a formal Serbian-Romanian framework covering hydrological, operational and environmental issues.
Environmental Permitting Will Influence Investment Decisions
The project is located within the wider Đerdap area, one of Serbia’s most environmentally sensitive protected regions. Future development will require assessments covering reservoirs, tunnelling, access infrastructure, biodiversity, water regimes and cumulative effects on the Danube corridor.
In addition to an environmental impact assessment, potential investors and lenders are expected to require environmental and social studies, public consultation procedures, biodiversity assessments, transboundary reviews and mitigation plans. These requirements will influence whether the project attracts institutional capital and international financing.
Storage Competition Expands as Battery Capacity Grows
Đerdap 3 would enter a market where battery storage technologies are developing rapidly. Battery systems are increasingly used for short-duration flexibility, frequency regulation and intraday electricity trading because of their modular structure, shorter construction timelines and declining costs.
The proposed hydropower facility would compete in a different segment, relying on its large-scale storage duration and system resilience. With hundreds of gigawatt-hours of energy equivalent, Đerdap 3 would target long-term balancing, seasonal stress management, reserve capacity and renewable integration. The project’s financial model would therefore need to focus on services that large reservoirs can provide beyond short-duration battery applications.
Wholesale electricity trading alone would not be sufficient to support a multibillion-euro investment. The project would require a framework covering capacity payments, reserve procurement, ancillary services, balancing-market access and potential cross-border flexibility revenues.
U.S. Participation Expands Strategic Dimension
The involvement of U.S. companies changes the strategic context of the project, although it does not automatically provide financing commitments. For Washington, Đerdap 3 represents an opportunity to participate in major Balkan electricity infrastructure at a time when storage, grid resilience and flexibility are becoming increasingly important elements of energy security.
For Serbia, the project provides an opportunity to diversify energy-sector partnerships involving Russian energy links, Chinese infrastructure contractors and European institutional financing. The financing structure could potentially combine state support, export-credit participation, development-finance involvement, commercial lending and contractor-related financing. Lenders would still require clarity on project revenues, payment obligations, capacity mechanisms and the ability to monetise regional electricity-system services.
EPS Faces Strategic Infrastructure Decision
For EPS, Đerdap 3 could become either a major stabilising asset or a significant financial commitment. A successful development model would depend on phased implementation, proven technical studies, transparent revenues, cost controls, environmental approvals and a financing structure that balances domestic and regional benefits.
The project’s engineering risks include tunnels, underground structures, reservoirs, slopes, hydraulic systems and electromechanical integration. These factors make the quality of FEED documentation and risk allocation between contractors, investors and public institutions critical. A fixed-price construction model would not remove risks unless early studies, geological assessments and contractual provisions adequately address potential cost increases and delays.
The strategic value of Đerdap 3 is also linked to Serbia’s broader industrial and energy transition goals. The country is seeking to expand renewable generation, attract manufacturing investment, develop industrial electricity demand and improve long-term supply reliability. A large-scale storage facility could support greater use of renewable power by making electricity supply more predictable and flexible for industrial consumers.
The regional electricity market is also becoming more complex as solar capacity expands, coal facilities age, hydrological conditions change and cross-border price signals become increasingly important. Located on the Danube corridor, Đerdap 3 could potentially provide flexibility services across Southeast Europe, including markets connected with Hungary, Romania, Bulgaria, Croatia, Bosnia and Herzegovina, Montenegro and Greece. The next stages of development will determine whether the project can move from a strategically significant proposal toward a financially viable infrastructure investment. The outcome will depend on feasibility studies, environmental approvals, Serbian-Romanian coordination, procurement standards and the final financing structure.
