Finland's radical answer to renewable energy's biggest headache: The world's largest sand battery

The small Finnish town of Pornainen has commissioned the world's largest commercial sand battery, developed by Polar Night Energy and operated by Loviisan Lämpö. The 13-meter-tall, 15-meter-wide facility uses 2,000 metric tons of crushed soapstone to store thermal energy, providing 100 MWh of heat capacity. It can cover nearly one month of the town's summer heating demand and one week in winter. The battery has reduced greenhouse gas emissions from the local heating network by almost 70% and cut wood chip use by 60%. CEO Tommi Eronen highlighted the advantage of sand batteries over lithium-ion batteries as they require no rare earth materials. The technology works by heating sand with excess renewable electricity, storing heat for days or weeks, then releasing it via heat exchangers to warm water for district heating. The project is ten times larger than a 2022 prototype, demonstrating scalability for regional heat storage.