World’s Largest Sand Battery Begins Operating in Finnish Town

Finland has launched the world’s largest sand battery in the town of Pornainen, designed to store 100 MWh of thermal energy generated from renewable sources like solar and wind. The battery, developed by Polar Night Energy and using 2,000 tons of crushed soapstone, provides one megawatt of thermal power to the local district heating system, enabling it to eliminate oil use and reduce wood chip consumption by about 60%, cutting carbon emissions by nearly 70%. This industrial-scale sand battery can store heat for weeks and release it at temperatures up to 400-600 degrees Celsius, covering heating needs for about a week during winter. The technology offers a cost-effective and efficient way to address energy storage challenges related to variable renewable energy sources, supporting Finland’s goal of climate neutrality by 2035. Additionally, Polar Night Energy is exploring power-to-heat-to-power applications to convert stored heat back into electricity, potentially enhancing grid stability and integrating with Finland's electricity reserve markets. The project highlights a growing interest in thermal batteries as a complementary solution to lithium-ion batteries for energy storage and decarbonization of heating infrastructure worldwide.