Energiasalv has published an invitation to tender on the international platform Mercell. The tender is for constructing and designing a 500-megawatt underground pumped hydro energy storage plant in Paldiski. Interested parties worldwide, including large-scale underground mining, underground infrastructure, pumped storage, design, and engineering companies, are invited to collaborate and form an alliance to design and construct this water storage facility. The project includes the development of the plan, execution of civil works, and electromechanical works.


The construction of Estonia’s first pumped hydro energy storage plant in Paldiski will begin in Q2 of 2025, 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 to the challenges the energy sector is facing.


“We’ve chosen an integrated project delivery model for the Zero Terrain Paldiski PHS and are therefore seeking experienced partners (contractors, designers) to develop and implement the project collaboratively,“ explained Phil ScottChief Project Officer of Energiasalv.


Additionally, Energiasalv is looking for experienced contractors for the Zero Terrain Paldiski PHS electromechanical equipment.

According to Phil Scott, the tendering procedure for the electromechanical works will culminate in selecting and nominating a reputable and experienced electromechanical contractor. This contractor will be a constant partner for Energiasalv and other alliance members throughout all three project phases: Development, Implementation, and Operation & Maintenance.


The tendering procedure will consist of two stages ahead of the final decision to proceed with the alliance and electromechanical works mid 2024. The completion and award of the alliance tender are expected in late July, and the results for electromechanical works are scheduled in June. The selected tenderers will then progress to the development stage, planned to run from August 2024 until the first quarter of 2025, when the Zero Terrain Paldiski PHS project will be ready to commence with the implementation/construction phase.


The project is a pilot demonstration of the advanced Zero Terrain technology and showcases its potential before expanding globally.

Phil Scott says the tender offers a unique opportunity to engage with the groundbreaking Zero Terrain technology. Unlike conventional pumped hydroelectric energy storage confined to mountainous terrain, our innovation broadens possibilities to include flat terrain. Zero Terrain Paldiski PHS represents a significant advancement in traditional hydroelectric energy storage, enabling cost-effective deployment of storage technology in diverse locations worldwide.


“Following the significant global interest observed during the Call for Expression of Interest last autumn, we anticipate the project’s appeal to the shortlisted parties from that process,” stated Scott.


Tender teasers for the alliance and electromechanical works are issued through the tendering platform Mercell. Tenders will be published according to the timeline for the alliance on the 14th of February and for electromechanical works in April 2024.


More details about the project:

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


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, Ronnivara 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 periods of low wind or solar power availability. This production level is equivalent to Estonian households’ average daily electricity consumption.


We invite you to regularly visit our homepage at for company and project updates.



Please find more information about the tenders on Mercell platform:

“Alliance Partners Selection – Zero Terrain Paldiski PHS Project”

“Electromechanical Equipment Tender – Zero Terrain Paldiski PHS Project”

Share this post


Lorem ipsum dolor sit amet, consectetur adipiscing elit.


Integer efficitur condimentum ipsum, id porta lacus vestibulum et. Aenean quam nisi, consectetur ut feugiat non, dignissim fringilla velit. Etiam vitae dictum dolor. Nullam interdum, neque vehicula accumsan fringilla, orci libero fringilla sem, vel eleifend sapien tortor vel nisi. Ut ornare nibh at gravida vestibulum. Interdum et malesuada fames ac ante ipsum primis in faucibus. Praesent porttitor risus sit amet nisi molestie molestie. Sed lobortis, risus eget elementum mattis, orci neque congue libero, at egestas est purus in massa. Donec at mi condimentum, mollis dolor ut, pellentesque urna. Suspendisse potenti.