Finland has inaugurated the world's largest sand battery this week, a 1?MW/100?MWh thermal storage system developed by Polar Night Energy.

The industrial-scale unit in Pornainen began operating in June after district heating company Loviisan Lämpö commissioned it. The company now uses the sand battery as the main production facility in its district heating network.

Polar Night Energy said the battery has met expectations in its first months and exceeded guaranteed efficiency targets. It has replaced the area's old woodchip plant all summer.