Finland is now home to the world’s largest operational Sand Battery.
Developed by Polar Night Energy for Finnish district heating firm Loviisan Lämpö, the Sand Battery is a high-temperature thermal energy storage system that stores clean and affordable electricity as heat in sand or similar solid materials. It can be used to produce heat for both district heating networks and a wide range of industrial processes.
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The industrial-scale Sand Battery now serves as the main production facility for the district heating network in Pornainen, Finland, delivering 1MW of thermal power with a storage capacity of 100MWh—making it 10 times larger than the sand battery launched in Kankaanpää in 2022.
“The Sand Battery means a lot to Loviisan Lämpö. It allows us to drastically reduce our emissions and improve the reliability of heat production,” Loviisan Lämpö CEO Mikko Paajanen said.
The Sand Battery is expected to reduce annual CO₂-equivalent emissions from the local heating network by around 160 tons—cutting climate emissions in Pornainen’s district heating by nearly 70%.
With the launch of the Sand Battery, the use of oil in the Pornainen’s heating network will be completely phased out, and the consumption of wood chips will decrease by approximately 60%. The existing biomass boiler will continue to serve as a backup and will support the Sand Battery during peak demand periods.
The Sand Battery stands about 13m tall and 15m wide, and it uses approximately 2,000 tonnes of crushed soapstone as its thermal storage medium—a by-product from the production of Tulikivi’s heat-retaining fireplaces. In summer, the Sand Battery can cover almost a month’s heat demand in Pornainen, and in winter, close to a week.
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A key part of the Sand Battery’s profitability lies in optimising its operation according to electricity prices and Finland’s grid operator Fingrid’s reserve markets. In doing so, the Sand Battery also supports power grid stability, an essential enabler of the rapid growth of wind and solar energy. Thanks to its large storage capacity, the system allows electricity usage to be optimised over several days or even weeks.
