The PSH 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 mining residue and closed mining tunnels created during oil shale mining. The plant acts as a powerful storage unit, helping to ensure energy security and stability of the power network when launched.
The size and profitability of the investment will be specified with pre-design, and the pre-assessment of environmental effects will determine which environmental requirements and conditions must be taken into account during its construction.
According to Margus Vals, Member of the Management Board of Eesti Energia, the pumped-storage hydroelectric power plant will be able to provide various services to the energy markets, thus making it an important asset not only for the company but for the entire country.
“Ensuring Estonia's energy security and energy independence with our own assets is more important than ever before,” Vals said. “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 are created in the Baltic States to ensure the security of supply as greenly and cheaply as possible. Our pumped-storage hydroelectric power plant will be ready to enter the market in 2025-2026 in accordance with Elering's synchronization plans, if the necessary system services markets are created. The plant will provide solutions to several challenges at the same time, because in addition to ensuring security of supply, it promotes the introduction of renewable energy, helps to achieve waste-free production and reuses industrial areas.”
The 225 MW plant will act as a giant 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.
“Renewable energy production is essentially variable, so the forecast can differ widely from what wind and solar farms actually produce,” Vals noted. “Even two hours before the moment of production, the forecast can differ significantly from actual. To cope with this, the power system must have generation assets that can respond as quickly to ensure the balance of consumption and production along with the frequency. One of the technologies that enables such a quick response is a modern pumped-storage hydroelectric power plant that is able to load itself up and down in a matter of minutes.”
The project is unique because, as far as Eesti Energia is aware, oil shale or coal mines have not been used as water reservoirs for hydroelectric power plants. In addition, it is unique that the pressure height of the PSH plant, 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 concept of the planned pumped-storage hydroelectric power plant can be exported to other countries. The target group includes countries whose land relief is not suitable for the construction of a classic pumped-storage hydroelectric power plant and where there are closed or closing mines.