Eesti Energia is planning to build a pump hydroelectric power station

The planned pump hydroelectric power station is the first in Estonia. The first steps, preliminary design, and preliminary environmental impact assessment, are in preparation. The completed station will help with the desynchronization of the Russian energy system.

The pumped hydroelectric power station is going to be in Ida-Virumaa, in the area of the Estonian mine. The power station is a large-scale circular economy project, and the construction uses limestone rubble and tunnels of closed mines. The tunnels are there from the mining of oil shale. The station acts as a power recorder, helping to provide energy security and stability to the power grid when it starts up.

The pre-design will give the knowledge of the size and profitability of the investment. The pre-assessment will also present the environmental effects and helps to consider what requirements and conditions are necessary throughout the construction.

Margus Vals, the Eesti Energia board member, notes that the power station will benefit the company and the whole country. The station can add various services to the energy market, making it an important asset.

"Ensuring Estonia's energy security and independence with our assets is more important than ever," says Vals. "In light of the connection to the continental European electricity system is to be ready for 2026 at the latest, energy markets and production or storage assets must be created in the Baltic States, with which security of supply can be ensured as greenly and as cheaply as possible. We are ready with Estonia's pumped hydroelectric power plant in 2025-2026 to enter the market under Elering's synchronization plans when the system service markets are ready. The pumped hydroelectric power plant offers a solution to several challenges simultaneously because, in addition to ensuring the security of supply, it promotes the introduction of renewable energy, helps to achieve waste-free production, and reuses industrial territory.

"Up to 225MW power station acts as giant storage. The establishment of the upper part of the station is on the tailing structure. The lower reservoir is going to be in the closed mine tunnels area. Suppose it happens that the electricity levels are down in the energy system. In that case, water is passed from the upper reservoir through pipes to an electric turbine, which converts current energy into electrical energy. When electricity is cheap, the station pumps the water back up to repeat the process when needed. The station will start operating in 2026.

"Renewable energy production is inherently variable, and the production forecast can differ greatly from what wind and solar farms produce," Vals said. "Even two hours before production, the forecast can differ significantly from the actual production. Due to that, the power system must have generation assets that can respond quickly to ensure the balance and frequency of consumption and generation. One of the technologies that enable such a quick response is a modern pumped hydroelectric power station, which can load itself up and down in a matter of minutes."

The project is unique because, as far as Eesti Energia knows, the use of oil shale or coal mine will be the first in water reservoirs for hydroelectric power plants. In addition, it is unique that the pressure head of the pumped hydroelectric plant, for example, the height between the upper and lower water reservoirs, is increased by reusing the tailings from the enrichment of the rock mass of the Estonian oil shale mine.

The concept of the planned pumped hydroelectric plant can be exportable to other countries. The target group is countries whose land relief is unsuitable for constructing a classic pumped hydroelectric power station and where there are closed or closing mines.