Estonia’s first pumped hydro energy storage facility calls for Expression of Interest

We are excited to invite you to express interest in creating Estonia’s first pumped hydro energy storage facility. We have published an all-for non-binding Expression of Interest (EOI) from companies interested in constructing Paldiski PHS. Any submitted EOIs are non-binding.


The construction of Estonia’s first pumped hydro energy storage plant in Paldiski is scheduled to begin in the autumn of 2024, representing a significant milestone in developing the country’s inaugural large-scale energy storage facility. The 500MW underground Paldiski Pumped Hydro-Energy Storage (Zero Terrain Paldiski PHS) project, powered by the innovative Zero Terrain technology, secured the essential official permit in December 2022. Energiasalv’s Zero Terrain PHS plant in Paldiski is positioned as a pioneering solution in response to the challenges the energy sector is facing.


“We are pleased to announce the Call for Expression of Interest (EOI) phase, inviting companies interested in undertaking the construction of the 500 MW Zero Terrain Paldiski PHS to submit their non-binding EOIs. We aim to finalise the tender process during first half of 2024 and start construction on the plant in the autumn of 2024,” stated Sander Astor, the Chief Technical Officer of Energiasalv.


The project serves as a pilot demonstration of the advanced Zero Terrain technology and showcases its potential before expanding globally. The unique Zero Terrain technology enables the implementation of the 500 MW underground pumped-hydro storage plant with minimal environmental impact and land use requirements, making it suitable for urban areas. Energiasalv envisions utilising its innovative technology to address energy storage challenges worldwide, helping countries integrate renewable energy sources and ensure grid stability.


“Unlike conventional pumped hydroelectric energy storage, typically limited to mountainous terrain, the Zero Terrain technology also expands the possibilities to include flat terrain,” explained Astor. “It represents an innovative advancement of traditional hydroelectric energy storage, allowing for cost-effective storage technology deployment in various locations worldwide,” Astor explained.


The EOI is published through the Mercell procurement environment. Interested parties and potential tenderers are encouraged to contact Energiasalv via the provided LINK to Mercell for any inquiries or further information.


More details about the project:


Energiasalv’s Paldiski Pumped Hydro Energy Storage plant is an EU Project of Common Interest (PCI project). It is the only pumped hydro energy storage project in the Northern Baltic region that will also be the country’s largest facility.


As a strategic infrastructure project, the project has received support from the Connecting Europe Facility, managed by the European Climate, Infrastructure and Environment Executive Agency (CINEA). Energiasalv is jointly owned by AS Alexela, a leading Estonian energy company; Sunly AS, a Baltic-Polish renewable energy company, Combiwood Grupp OÜ, Warmeston OÜ, Kiikri Kodu OÜ, and Vool OÜ, owned by the company’s CEO.


With a storage capacity of 6GWh during a 12-hour storage cycle, the project aims to provide affordable electricity to consumers during low wind or solar power availability periods. This production level is equivalent to Estonian households’ average daily electricity consumption.


We invite you to regularly visit our homepage at for detailed updates and information throughout the tender process.

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