Supporting renewable energy with storage is essential, as it provides emissions-free energy, even when the wind is not blowing and the sun is not shining.
Zero Terrain (Energiasalv) Paldiski, the country’s first pumped hydro energy storage system project, was initiated in 2009 between several energy companies to help the Estonian energy system cope with the unpredictable fluctuations of renewable energy, and enhance supply reliability and energy security, ensuring a more stable and reliable electricity supply.
First, Zero Terrain Paldiski obtained the main building permits in December 2022, and the construction of the country’s first pumped hydro storage (PHS) plant will begin in 2025. The uniqueness of Zero Terrain pumped hydro storage technology lies in the fact that, compared to traditional plants built inside mountains, the company’s concept for PHS can be applied on flat land, opening the door to widespread energy storage globally.
One of a kind
Additionally, just recently, the company signed a memorandum of understanding (MoU) with the Estonian Ministry of Climate. With this cooperation, Zero Terrain is collaborating closely with the government to devise solutions to enable the realisation of the PHS project in Estonia, including support for the securing of capital and addressing market challenges. Peep Siitam, the founder and CEO of Zero Terrain, said that Zero Terrain Paldiski represents a notable milestone in Estonia’s energy system. Paldiski PHS-plant is the only greenfield pumped hydro energy storage project in the northern Baltic region and will also be the largest facility in the country.
It’s also massive. During the nominal operating cycle of 12 hours, Zero Terrain Paldiski generates 6GWh of power to the grid, which is somewhat more than the average daily consumption of all Estonian households, said Peep Siltam, the founder and CEO of Zero Terrain, at the Energy Hackathon organised by the Ministry of Climate in January 2024.
Signing the MoU is a significant step forward in Zero Terrain’s journey towards a clean and secure energy future. “We believe there can’t be a renewable-energy-driven energy system without large-scale, energy storage. This collaboration signifies the cooperation and commitment to driving positive change in the Estonian renewable energy landscape.”
Furthermore, in 2024, Zero Terrain received a grant of 1.98 million euros from the state’s applied research programme for development and implementation activities, for minimising the environmental footprint, for exporting the technology to countries where large-scale storage has not yet been possible due to geographical constraints, and for engaging new investors in Zero Terrain Paldiski.
As the problem of long-term storage is a global one and the advancement of traditional PHS technology opens up global export opportunities, Zero Terrain is mapping out potential interested parties from both Europe and the GCC region. Mario Vee, Zero Terrain business development lead, explained that Zero Terrain technology was presented, for example, at the COP28 climate meeting in Dubai at the end of last year and during a visit to Saudi Arabia by the former Estonian Minister of Economy, Tiit Riisalo. “The aim was the same on both occasions: to validate the applicability and competitiveness of our technology in the target markets compared to others and to establish direct contacts with potential partners for Zero Terrain projects elsewhere in the world. In both cases, the objectives were met, and we received confirmation that there is interest. We are at the beginning of our export journey, but the initial feedback is positive. However, the first agreements are expected perhaps only in a year’s time,” Vee added.
Going deep and wide
The construction of the Zero Terrain Paldiski 500 MW hydro storage plant will involve going deep underground, says Mario Vee, Business development lead at Zero Terrain. During construction, 10 reservoirs will be built, for which several openings will be made through complex geology – 200 metres of sedimentary rock and the hard rock below this, in total up to 750 metres. It means excavating about 15 million tonnes of gneiss in the first stage. This is a completely new mineral resource for Estonia, and until now it has been expensive to reach, and it has simply not been efficient to do so. Gneiss is a crystalline rock whose parameters are significantly superior to and more durable than limestone. The new material will be produced in accordance with the circular economy principle – industrial water is circulated, and the groundwater level will not drop, since there is no pumping, and appropriate equipment will be used to stop dust spreading.
Crushed gneiss is successfully used in road construction elsewhere in the world, and the quantity produced in Paldiski in the first phase will last for 5–6 years. Compared to today, when 100 million euros is invested in road reconstruction every year, between 2026 and 2050 using gneiss, over 1 billion euros less would be spent on road reconstruction, because the roads would last longer and there would be larger intervals between major reconstruction – from 20 years currently, to 30 years. So far, gneiss has been imported in small quantities from Finland, Sweden, and Norway.
Part of the 1.98 million euro grant recently received through Enterprise Estonia’s applied research programme will go to converting extracted gneiss into aggregate products using the best available technology and the smallest possible footprint (i.e. efficient and economical machinery). In addition, minimal use is to be made of off-system environmental resources, which means that water used in the production process is not drawn from a water body or a well, but the water used in crushing is recycled – it is purified and reused. Unlike in almost all limestone quarries in Estonia, separate groundwater ingress pumping is not required for gneiss extraction.