Finnish City Inaugurates 1 MW/100 MWh Sand Battery - CleanTechnica

The Finnish city of Pornainen has inaugurated a large-scale sand battery system—a 1 MW/100 MWh thermal energy storage solution developed in collaboration between the local district heating company Loviisan Lämpö and Polar Night Energy. This innovative sand battery, housed in a 42-foot-tall steel cylinder filled with 2,000 tons of crushed soapstone chips, stores excess renewable electricity as heat by circulating hot air through the crushed stone. The stored heat is then distributed via district heating pipelines to buildings, significantly reducing reliance on fossil fuels. The system is expected to cut carbon emissions from district heating by 70 percent, completely eliminating oil use and supplementing with carbon-neutral wood chips. The sand battery operates with a round-trip efficiency of about 90%, offering a simple, safe, and durable alternative to chemical batteries, as it does not degrade or pose fire risks. It leverages software to heat the storage during periods of low electricity prices, which has enabled the district heating operator to pay only