Finland commissions world’s largest sand battery for thermal storage

Finland has brought online a 1 MW/100 MWh sand battery developed by Polar Night Energy in Pornainen. Commissioned by district heating firm Loviisan Lämpö in June, it now serves as the main source for the local heating network.

The system, built with 2,000 tons of crushed soapstone, is 13 meters high and 15 meters wide. It provides 1 MW of thermal power and 100 MWh of storage, replacing the area’s woodchip plant over the summer while surpassing efficiency guarantees.

Polar Night Energy said the battery can also trade in reserve markets, storing energy based on price signals and Fingrid’s instructions. The storage can shift consumption across days or weeks and help stabilize the grid.

Polar Night Energy is negotiating larger projects and will soon launch a pilot to test power-to-heat-to-power use of its sand battery.