Serbia has opened a RSD 625 million public procurement procedure, approximately €5.3 million, for planning and initial technical documentation for the Đerdap 3 pumped-storage hydropower plant. The procurement is part of the project’s preparatory work, advancing a decades-old initiative into a more substantive development phase.
The Ministry of Mining and Energy is seeking a consultant or consortium to prepare the General Design, Preliminary Feasibility Study, Special-Purpose Spatial Plan and Strategic Environmental Assessment. Bids are due by 20 August 2026.
The contract is an early-stage development assignment rather than a construction tender. It is intended to test whether Đerdap 3 can be configured, permitted and financed as a technically coherent project while managing impacts on the Danube, the existing Đerdap hydropower system, navigation, protected areas and Serbia’s cross-border water relationship with Romania.
Pumped-storage concept, capacity range and proposed reservoirs
Đerdap 3 is designed to operate as a large water-based electricity-storage system. During periods of low demand or excess renewable generation, electricity would be used to pump water from the Đerdap 1 reservoir into one or possibly two upper reservoirs.
When electricity demand and prices rise, stored water would be released through reversible pump-turbine units to generate power. Current concepts place installed capacity in a range of 1,200 MW to 2,400 MW, with the ministry examining an intermediate configuration of about 1,800 MW.
A hydraulic head of around 400 metres is considered technically possible. Potential upper-reservoir locations under assessment include Pesača and Brodica on the Northern Kučaj mountain range.
The Danube and the existing Đerdap 1 reservoir would serve as the lower reservoir. The project area is located between Golubac and Donji Milanovac, about 65 kilometres upstream of Đerdap 1.
Main infrastructure scope and system role during pumping and generation
The full scheme would require intake and outlet structures on the Danube. It also includes large underground or surface waterways, pressure tunnels and penstocks, upper dams and reservoirs, reversible generating units, a powerhouse, transformers and switchgear.
A high-capacity connection to the Serbian transmission network operated by Elektromreža Srbije would also be required. The project’s design scope goes beyond another hydropower station because pumping would consume more electricity than is returned later due to hydraulic, electrical and mechanical losses.
The value proposition described in the procurement materials centres on shifting electricity between periods. It would absorb surplus wind and solar generation, supply peak demand and provide rapid-response balancing, reserves, frequency control and system-restoration capability.
Indicative investment range and storage duration options
The project has an indicative investment value of approximately €2.6 billion. Final cost estimates cannot be treated as reliable until decisions are made on plant configuration, reservoir volume, geological conditions, tunnelling requirements and grid-connection design.
For the 1,800 MW configuration currently under discussion, the headline estimate implies capital intensity of around €1.44 million per MW, or €1,440 per kW. The procurement materials note that complex tunnelling, difficult geology, environmental mitigation and compensation measures, grid reinforcement and imported electromechanical equipment could move the construction envelope towards €3 billion–€3.4 billion.
A full build-out at 2,400 MW could require €3.2 billion–€4 billion, depending on storage duration and the number of upper reservoirs. The documentation tender budget of about €5.3 million is described as roughly 0.2% of the currently indicated construction value.
The study work is expected to support decisions on optimum capacity, energy-storage duration and construction sequence before Serbia negotiates an engineering, procurement and construction contract. A weak preliminary design could affect configuration choices by locking in an oversized option or leaving geological exposure or environmental baselines insufficiently defined.
Bilateral water management with Romania and grid connection studies
A key element in development is Romania’s role in operating constraints for the shared Danube system. Although Đerdap 3’s power station and proposed upper reservoirs would be located on Serbian territory, it would draw water from a reservoir forming part of the jointly managed Iron Gates hydropower and navigation system.
Pumping and generation cycles could influence Danube water levels, navigation conditions and operation of Đerdap 1 and Đerdap 2, which Serbia and Romania jointly operate. On 16 July 2026, the two countries signed a memorandum in Bucharest to facilitate information exchange and technical assessment.
The memorandum states that any development must remain compatible with electricity production at Iron Gates I and II while protecting riverside areas and maintaining navigation on the Danube. The procurement materials describe this as an interface risk because operating rules cannot be designed solely around Serbia’s electricity-market interests.
The Preliminary Feasibility Study is expected to model not only engineering performance but also commercial consequences from bilateral water-management constraints. It also notes that restrictions could affect revenues if pumping during low-price hours or generating during scarcity periods is limited.
The connection studies will need to examine how injecting up to 2,400 MW at one point affects the Serbian transmission system. The scope includes nearby 400 kV infrastructure, internal Serbian bottlenecks and cross-border corridors towards Romania, Bulgaria and Hungary.
Tender deliverables for environmental assessment and permitting alternatives
The Strategic Environmental Assessment must compare alternatives rather than justify a single preferred configuration. The assessment topics include location and number of upper reservoirs, surface versus underground infrastructure choices, construction traffic impacts and biodiversity effects.
The Strategic Environmental Assessment also needs to cover water quality considerations, sediment movement risks, landscape impacts and cumulative effects with existing hydropower assets. The proposed development sits within the wider Đerdap Gorge landscape affecting areas described as having high ecological, cultural and archaeological value, including parts of Đerdap National Park.
The procurement materials say upper-reservoir construction would require dams, excavation work, access roads, transmission infrastructure and disposal areas for substantial quantities of rock and soil. It also states that environmental mitigation timeframes could influence bankability when comparing configurations such as a technically attractive 2,400 MW scheme.
Tender stage timing; US partner process; financing structure expectations
The new tender advances preparation but does not make Đerdap 3 construction-ready. The next stage described in the materials would convert a concept into a modern storage asset with confirmed reservoir design, coordinated Serbian-Romanian operating arrangements, lender-grade revenue modelling inputs and competitive contracting strategy.
A political timetable cited in the materials envisages completion of a first phase by around 2036, with a wider horizon potentially extending to 2038. The programme described requires several years for planning steps including geological investigation, environmental studies, cross-border coordination plus land acquisition and permitting before main construction begins.
The initial contracting plus front-end engineering phase is indicated at approximately 36 months. The state has linked Đerdap 3 to strategic energy cooperation with the United States under a bilateral framework that entered into force in March 2025, following an intergovernmental agreement signed in 2024.
A public call inviting US companies to express interest closed on 25 June 2026, with submissions from six companies. The process aims to identify a strategic supplier or partner capable of supporting front-end engineering work potentially leading to a later EPC contract; requirements included experience in hydropower or comparable infrastructure plus delivery experience for projects exceeding €
