The language of the text is English.
A Finnish town has launched the world’s largest sand battery, a groundbreaking thermal energy storage system designed to harness renewable power. The facility in Pornainen, Finland, stores excess electricity from solar and wind sources as heat, which is then distributed through the local district heating network. Developed by Polar Night Energy, this industrial-scale solution provides a cost-effective and sustainable way to heat buildings, dramatically reducing the town’s carbon emissions and reliance on biomass. The project represents a significant advancement in long-duration energy storage, offering a viable model for communities globally.
In the town of Pornainen, a massive steel silo measuring 13 meters (about 43 feet) high and 15 meters (about 49 feet) wide now serves as the primary heat source for the community. This innovative system, with a capacity of 100 megawatt-hours, can store enough thermal energy to cover the town’s heating needs for a full month in the summer or one week during the harsh winter. The technology is projected to eliminate approximately 160 tons of CO2 equivalent emissions annually and slash the consumption of wood chips by 60 percent, with the existing biomass boiler retained for backup purposes.
The sand battery operates by using surplus renewable electricity to heat a storage medium—in this case, crushed soapstone—to around 500 degrees Celsius through resistive heating. This heat can be stored efficiently for months with minimal loss. When heat is needed, hot air is circulated from the silo to warm water for the district heating system, which then flows through underground pipes to homes, schools, and other public buildings. This thermal storage method is highly economical, costing about a quarter of the price of equivalent lithium-ion battery storage.
This installation is roughly ten times larger than Polar Night Energy’s first commercial prototype, which went online in Kankaanpää in 2022 and proved its effectiveness after Russia halted gas supplies to Finland. For the Pornainen project, the company opted for crushed soapstone, an industrial byproduct from a local fireplace manufacturer, demonstrating the technology’s flexibility to use various locally sourced, non-sand materials. Local officials report that the project has been well-received by residents, aligning with the municipality’s strategic goal of achieving carbon neutrality.
With this success, Polar Night Energy is exploring further applications and global expansion. The company is already planning a new pilot project to test the conversion of stored thermal energy back into electricity, a development that could significantly broaden the technology’s scope. As the world transitions to intermittent renewable energy sources like solar and wind, solutions like the sand battery offer a practical and scalable way to ensure a stable and sustainable energy supply.