Polar Night Energy Builds Industrial-Scale Sand Battery in Pornainen

Finnish cleantech company Polar Night Energy has launched a groundbreaking Sand Battery in Pornainen, integrated into Loviisan Lämpö’s district heating network. Delivering 1 MW of thermal power with a 100 MWh storage capacity, this installation is ten times larger than the 2022 pilot in Kankaanpää.

🔥 what it means for Pornainen

Using sand as a heat store lets Loviisan Lämpö cut emissions by nearly 70%, eliminate oil entirely, and reduce wood-chip use by 60%. Energy is held in 2,000 tonnes of crushed soapstone, a circular by-product of Tulikivi’s fireplace production. In summer it can cover almost a month’s heating demand; in winter, nearly a week.

⚡ how it works

The Sand Battery converts renewable electricity into high-temperature heat stored in granular media. That heat is later fed to district heating or industrial processes. With variable solar and wind, long-duration thermal storage balances the grid while enabling fossil-free energy.

🏗 a collaborative effort

The build involved 40 subcontractors and 100+ workers over a year. Business Finland provided funding, while Elisa Industriq optimized operations with an AI-driven charge/discharge scheduler to maximize environmental and economic benefits.

🔄 circular economy in action

Unlike lithium batteries, the Sand Battery relies on abundant, recyclable soapstone waste. It showcases how industrial side streams can be repurposed into climate solutions—accelerating the circular economy and reducing dependence on scarce materials.