The world’s largest sand battery, developed by Polar Night Energy, is now operational, serving as the main facility for the district heating network in Pornainen, Finland.

Polar Night Energy has built an industrial-scale sand battery in Pornainen for Loviisan Lämpö’s district heating network. The new battery delivers 1MW of thermal power and offers a storage capacity of 100MWh, making it ten times larger than the sand battery launched in Kankaanpää in 2022.

The sand battery is a high-temperature thermal energy storage system that stores electricity as heat in sand or similar solid materials. The thermal storage medium used in sand batteries can include byproducts from manufacturing or mining industries, meaning there’s often no need to extract virgin materials. It can be used to produce heat for both district heating networks and a wide range of industrial processes. The sand battery is expected to reduce annual CO2-equivalent emissions from the local heating network by around 160 tonnes, cutting climate emissions in Pornainen’s district heating by nearly 70 per cent.

The battery supports power grid stability, acting as an enabler for the 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.

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