Unique thermal energy storage system to be built in Slovakia by 2030

Slovak company Vodohospodárska výstavba and US-based Westinghouse Electric Company have signed a memorandum of understanding to assess the feasibility of building a unique commercial pumped thermal energy storage system. The first of its kind, the system aims to become a model solution for Europe and the rest of the world.

The proposed project would provide long-duration energy storage to store surplus electricity generated by hydropower plants operated by Vodohospodárska výstavba, with capacity of up to one gigawatt. This technologically innovative solution is designed to store energy for periods ranging from 8 hours to several days. The system will enable more flexible use of renewable energy sources in Slovakia while helping to improve the stability and resilience of the energy grid.

The solution, called Pumped Thermal Energy Storage (PTES), is expected to have a service life of around 60 years, and its greatest advantage is its unlimited cycling capacity. This will enable more flexible use of existing hydropower generation. The agreement provides for a two-month preliminary study to analyse the project's economic and environmental feasibility and sets a framework for 12 months of preliminary engineering and design work. The PTES system is expected to be commissioned by 2030 and will use local suppliers, creating opportunities for similar projects across Europe and the world.

The memorandum was signed by Slovak Minister of Environment Tomáš Taraba, Vodohospodárska výstavba CEO Peter Molda, Westinghouse Senior Vice President of Commercial Operations Elias Gedeon, and Westinghouse President for the Czech Republic and Slovakia Petr Brzezina.

"Our PTES system will enable Slovakia to store hundreds of megawatt-hours of clean electricity during periods of low demand and supply it when it is most needed, improving system reliability and potentially reducing overall energy costs," said Lipman, president of Westinghouse's energy systems division.

Westinghouse developed the PTES system in collaboration with Echogen, a leading supplier of energy systems based on supercritical carbon dioxide (sCO₂). The solution uses an electrically powered heat pump to draw energy from the grid and convert it into stored thermal energy, which can later be converted back into electricity using a heat engine. PTES offers a lower levelized cost of energy storage in long-duration applications when used alongside surplus generation capacity from all sources, including renewable (hydro, wind and solar) and conventional energy sources.

Vodohospodárska výstavba is a state-owned enterprise under the Ministry of Environment of the Slovak Republic, focused on the construction, management and operation of water infrastructure in Slovakia, particularly hydropower plants and flood-protection structures. Its most significant water projects include: Gabčíkovo Waterworks (the largest run-of-river hydropower plant, with a capacity of 720 MW); Čierny Váh (the largest pumped-storage plant, with a capacity of around 735 MW); and Liptovská Mara (198 MW).