Finland unveiled the world’s largest sand battery in Pornainen on June 17, 2025, a 1 MW, 100 MWh thermal storage system developed by Polar Night Energy, per a TechCrunch report.
Using 2,000 tons of crushed soapstone, a byproduct of Tulikivi’s fireplace manufacturing, the battery stores heat at 500 to 600°C with 99 percent efficiency, reducing Pornainen’s heating network emissions by 70 percent, or 160 tons of CO₂ annually, according to a 2025 Euronews article.
Soapstone’s superior heat conduction over sand, per a 2025 PV Magazine report, enhances performance, enabling the system to meet a week’s winter heating demand or a month’s summer demand for Loviisan Lämpö’s district network. This circular economy approach positions Finland as a leader in sustainable storage innovation.
Can Sand Batteries Scale Globally?
The Pornainen battery, ten times larger than Polar Night Energy’s 2022 Kankaanpää pilot, demonstrates scalability, per a 2025 Energy-Storage.News article.
The Pornainen battery can store renewable energy as heat for months with only a minimal loss of 10 to 15 percent, effectively addressing the intermittency of wind and solar, which is critical since Finland’s grid relies on 43 percent renewables and 26 percent nuclear, per a 2025 TechCrunch report.
Polar Night Energy’s €7.6 million funding in 2024 supports plans for even larger installations, potentially 100 times bigger, per a 2025 USA Solar Cell article.
Global interest is rising, with startups like Scotland’s Sunamp and U.S.-based Fourth Power exploring thermal storage, per TechCrunch. However, scaling requires abundant, sustainable materials like soapstone or mine waste, which Polar Night is testing, per a 2025 Polar Night Energy statement.
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Will Grid Integration Drive Adoption?
The battery’s integration with Finland’s grid, optimized by Elisa’s AI to charge during low-cost renewable surplus, maximizes economic viability, per a 2025 Energy News report.
It participates in Fingrid’s reserve markets, stabilizing the grid as renewables grow, with Finland’s 94 percent carbon-neutral electricity in 2023 amplifying its impact, per a 2025 Polar Night Energy release. This flexibility could save Loviisan Lämpö significant costs while generating revenue.
Other nations, like Germany with its 200 MW water-based thermal storage, are adopting similar systems, per a 2025 New Atlas article. Finland’s model, costing €10 per kWh, per TheNextWeb, could inspire widespread adoption if infrastructure and policy support align globally.
Circular Economy Boosts Sustainability
By repurposing soapstone waste, the Pornainen project embodies circular economy principles, reducing reliance on virgin materials, per a 2025 Interesting Engineering report.
This approach cuts costs and environmental impact, with Tulikivi’s CEO Heikki Vauhkonen noting its alignment with sustainable mining practices.
Polar Night’s material flexibility, using sand-like byproducts, enhances its global applicability, per a 2025 Polar Night Energy statement.
This model could transform industries like mining, where waste rock could serve as storage media, per a 2025 Polar Night Energy report.
Finland’s early success may drive other nations to adopt similar waste-to-energy strategies, amplifying the technology’s global reach.
Did you know?
In 2022, Polar Night Energy launched the world’s first commercial sand battery in Kankaanpää, Finland, with 8 MWh capacity, paving the way for the Pornainen scale-up.
Fossil Fuel Phase-Out Accelerates
The battery eliminates oil from Pornainen’s heating and cuts wood chip use by 60 percent, with a biomass boiler as backup, per a 2025 Renewable Energy Magazine report. This aligns with Pornainen’s 2035 climate neutrality goal, per Loviisan Lämpö’s CEO Mikko Paajanen.
Finland’s leadership in electrifying heating, a major emissions source, sets a precedent for cold-climate regions, per a 2025 Energy News report.
However, global adoption faces challenges, including material availability and infrastructure costs. Technologies such as lithium-ion batteries, which are less suited for long-term heat storage, emphasize the niche advantage of sand batteries, according to a 2025 Dezeen article.
What Lies Ahead for Sand Battery Technology?
Finland’s Pornainen sand battery showcases a scalable, efficient solution for storing renewable energy, slashing emissions, and leveraging circular economy principles.
Its grid integration and soapstone innovation position Finland as a trailblazer, but global scaling hinges on material access and infrastructure.
As thermal storage gains traction, the technology could redefine energy systems. Will sand batteries power the world’s clean energy future?
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