Finland Activates World's Largest Sand Battery for Renewable Energy Storage
Finnish startup Polar Night Energy has commissioned the world's largest commercial sand battery in Pornainen, Southern Finland. The 13-meter-tall silo contains 2,000 metric tons of crushed soapstone and can store 100 MWh of thermal energy. It uses excess wind and solar power to heat air, which is circulated through the soapstone to reach temperatures of 400-600°C. The stored heat is released to a district heating network, providing warmth for 5,000 residents for up to a week in winter or nearly a month in summer. An AI system automatically charges the battery when electricity prices are low and discharges during peak demand. The company claims the battery cuts greenhouse gas emissions by 70% and reduces wood chip use by 60%. Unlike lithium-ion batteries, sand batteries do not degrade, require no rare-earth materials, and offer low-cost long-duration storage. A larger 250 MWh system is planned for completion in 2027.
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