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Eesti Energia has entered into an agreement with Engineering Firm Steiger to start the pre-FEED study of its planned pumped-storage hydroelectric power plant (PSH) with the purpose of determining the exact location for the necessary facilities and specifying the investment cost.

The pumped-storage hydroelectric power plant planned for the industrial area of Estonia Mine in Ida-Virumaa is a large-scale circular economy project, the construction of which takes advantage of mine tailings and closed mining tunnels created during oil shale mining. The plant will act as a powerful storage unit, helping to ensure energy security and stability of the power network when started up.

According to Veljo Aleksandrov, Project Director from Eesti Energia, the development works are proceeding as planned, and each next stage brings closer the completion of the storage unit that can offer various services to the energy markets and is therefore important for the whole of Estonia.

“Ensuring Estonia's energy security and energy independence with our own assets is more important than ever before. In view of the connection to the continental European electricity system planned for 2026 at the latest, it is extremely important that the necessary energy markets and production or storage assets be created in the Baltic States to ensure the security of supply as greenly and cheaply as possible,” Aleksandrov said. “International interest toward our project is great because it is a unique project. We will carry out comprehensive and versatile studies over the next year in order to provide certainty that our solution will work.”

The analysis of the technical solution to be completed in the spring will be followed by preliminary design with the necessary studies. These works should be completed by the end of 2023 and the investment decision should be made in the first half of 2024.

According to Hardi Aosaar, Project Geologist from Engineering Firm Steiger, the task for the company is unique in the world, but their team is the best one to solve it.

“The pumped hydroelectric power plant project is a good example of how to think 'outside the box'. The project plans to reuse the infrastructure of an old oil shale mine, waste rock generated in the mining industry, and as a result to contribute to the security of supply of Estonian energy,” Aosaar said. “Besides a very interesting engineering-technical challenge, the project will be a good opportunity for us to cooperate with our German partner Fichtner. We have gathered top-level Estonian construction geology and mining engineering competences to help us. We believe that our team is the best one in the world for solving such unique tasks, and we can boost the development of Eesti Energia's hyrdopower storage with our advice and assistance.”

The plant of up to 225 megawatts will act as a large-scale storage unit. Its upper reservoir will be built on a waste rock structure, and the closed mine will be used as the lower reservoir. When there is a lack of electricity in the energy system, water is passed from the upper reservoir through pipes to an electric turbine that converts energy from flowing water into electrical energy, after which the water enters the lower reservoir. At times when electricity is cheap, the water is pumped back up for the process to be repeated when needed. The plant will start operating in 2026.

The solution of Eesti Energia is unique as the pressure height of the facility, i.e. the height between the upper and lower water reservoirs, is increased by reusing waste rock from the enrichment process of rock mass from oil shale mining. The use of a mine as a water reservoir for a hydroelectric power plant also makes the project special.

The concept of the planned storage unit can be exported to other countries. The target group includes countries whose land relief is not suitable for a classic pumped storage hydropower plant (or the environmental effects of a plant in natural conditions are too great) and where there are closed or closing mines.

Finding a technical solution and the preliminary design of Eesti Energia's hydroelectric power plant is supported by Enterprise Estonia.