The world’s largest sand-based heat storage facility has been launched in Finland.

In Pornainen, Finland, the world’s largest sand-based heat storage facility has officially started operating. This is a joint project by Loviisan Lämpö and the startup Polar Night Energy. The installation has a thermal power capacity of 1 MW and an energy storage capacity of 100 MWh. It is ten times larger than the pilot project carried out in 2022 in Kankaanpää.

Reducing emissions and revolutionizing heating
The storage system will use about 2,000 tons of crushed steatite (commonly called “sand”). It will supply the district heating network in Pornainen and nearly completely eliminate the use of heating oil while reducing wood chip combustion by 60%.

According to Loviisan Lämpö, annual CO₂ emissions will be reduced by 160 tons, which amounts to nearly 70% of the emissions previously generated by the local heating system. In summer, the storage can provide heat for almost a month, and in winter for about a week. Additionally, the existing biomass boiler will remain on standby as a peak-load source.

Sand battery technology
The Sand Battery is a type of high-temperature thermal energy storage that stores excess cheap and green electricity (e.g., from wind farms and solar power) in the form of heat. This energy can then be used in district heating networks or industrial processes.

The technology addresses key challenges of the energy transition, such as balancing the grid with an increasing share of renewables, eliminating fossil fuel combustion, and utilizing waste resources. The storage system also participates in the system services market managed by the Finnish transmission system operator Fingrid.

System optimization with AI
Finnish company Elisa handles the system’s operation optimization using artificial intelligence solutions. Jukka-Pekka Salmenkaita from Elisa Industriq explains: “Our AI system automatically identifies the most cost-effective moments to charge and discharge the storage, significantly improving the operational and economic efficiency of the entire installation.”

An example of technology synergy and circular economy
The Pornainen project is also a great example of circular economy in practice. The storage medium is an industrial waste product—crushed steatite from the stove production of the company Tulikivi. As noted by the company CEO, Heikki Vauhkonen:

“Finland aims for climate neutrality and full circularity by 2035. This project shows how that can be achieved in practice through cross-sector collaboration.”

The investment was supported by Business Finland. Construction took about a year, involving over 40 subcontractors and more than 100 workers. Polar Night Energy delivered the installation as a turnkey solution. The company has already announced further deployments, including an innovative “power-to-heat-to-power” project in Valkeakoski, where thermal energy will be converted back into electricity.

A joint success of public and private sectors
The project received support from both the local government and the investor, CapMan Infra fund. Sauli Antila, investment director at CapMan Infra, says: “This investment perfectly aligns with our sustainability goals. Sand Battery technology is not only a modern solution but also a real way to reduce dependency on a single energy source and increase system resilience.”

Meanwhile, Antti Kuusela, mayor of Pornainen, emphasizes: “The project proceeded very smoothly. For our municipality, this is a milestone on the path to climate neutrality and proof that local government can be a leader in energy transition.”

Source: ess-news.com