Europe: World's largest sand battery goes live, cuts 70% CO2 emissions

The world’s largest industrial-scale sand battery has become fully operational in Pornainen, Finland, developed by startup Polar Night Energy for the local district heating company Loviisan Lämpö. This innovative thermal energy storage system uses 2,000 tons of crushed soapstone to store surplus renewable electricity as heat, delivering one megawatt of thermal power with a 100 megawatt-hour capacity. The sand battery can cover nearly a month’s heating demand in summer and up to a week in winter, supplying heat to municipal buildings and homes while significantly reducing reliance on fossil fuels. The installation is expected to cut Pornainen’s district heating CO2 emissions by nearly 70%, equivalent to about 160 tons annually, by eliminating oil use and reducing wood chip consumption by 60%. A biomass boiler remains as backup for peak demand periods. Beyond heat storage, the sand battery supports grid balancing by optimizing energy use based on electricity prices and reserve markets managed by Finland’s grid operator Fingrid, with digital services provided