Increasing the power system balancing capabilities of the Čierny Váh PHS is key to the further decarbonization of the Slovak economy, especially for reducing the share of fossil fuels in system regulation. The SE Integrator project will bring the necessary flexibility by using water – a clean, renewable resource.

EU has pledged to be climate neutral by 2050, setting itself on an ambitious decarbonization path. Each member state has created their Integrated National Energy & Climate Plan (INECP) in order to meet the target. Slovak INECP foresees significant uptake of electricity generation from renewable sources (wind and solar), some 1200 MW of new installed capacity, while the RepowerEU strategy sets of goal of over 500 GW of PV by 2030. This will pose a challenge to the grid, given the unstable production of these sources, hence adequate balancing capacity is needed to prevent critical events such as blackouts.

Čierny Váh PHSP will play a key role in stabilizing the grid in the upcoming decades, supporting the increase in intermittent generation of wind and solar power plants on the way to a net zero economy.

EU commitment to energy transition is also aimed at reducing its dependency on fossil fuels which could have political implications. By speeding up the green transition, fossil fuel need will decrease and hence also the pressure experienced by some EU countries, including Slovakia, to secure sufficient supply of gas and other fuels. To transform the economy heavily dependent on gas, rapid electrification of industry and heating sector is expected. This will cause an increased need for grid stability which SE Integrator project will bring, using a modern and efficient solution, without additional emissions.

The hybridization of the pumped storage with a battery will allow for baseload provision of ancillary services which will replace the grid regulation provided by fossil fuel power plants that will be decommissioned in the coming years. To quote Mike McWilliams, head of energy at London-based economic forecasting company CEBR and an advisor on hydropower for the World Bank, “batteries and pumped storage are not in competition, they are complementary: batteries are for rapid response and fast ramping, and active injection of power. Pumped hydro is a passive response in terms of system inertia. Batteries are good for stability, pumped hydro for security of supply. I am keen on having hybrid projects: pumped hydro with batteries. If you attach one-hour battery storage to pumped hydro, using the same switchyard, you have a very valuable grid stability tool.”

Čierny Váh PHS is currently one of the main providers of flexibility. It provides ancillary services to the Slovak TSO in order to ensure secure operation power system by activating the balancing energy as needed by the TSO. After the modernization, the balancing capabilities will increase.

The project will use the existing infrastructure and help increase the possibilities of system balancingregulation in a cost-effective way with minimal environmental and social impact. This is in line with the Integrated National Energy and Climate Plan: "maintain and support existing PHS capacity and operation and consider possible increase of storage capacity". The project follows various initiatives of the European Commission, such as 4th work package of the eStorage project financed by the European Union. What is the time frame of the project?

The project is currently in the "feasibility study" processing stage, where various technical aspects are analyzed in order to achieve the required project parameters. The project received the status of "Projects of Common Interest" (PCI) and is also evaluated by ENTSO-E in the Ten-Year Network Development Plan for 2024 (TYNDP 2024). The project is planned to be implemented by 2030.