New Industrial Sand Battery Filled with Soapstone Equal to 1,000 Fireplaces

Construction of the Sand Battery for Loviisan Lämpö is progressing as planned, with crushed soapstone—a by-product of Tulikivi’s fireplace production—serving as the storage medium.

Polar Night Energy is building an industrial-scale Sand Battery in Pornainen, designed to supply thermal energy for Loviisan Lämpö’s district heating network. Construction is proceeding according to plan.

The Sand Battery, developed by Polar Night Energy, is a thermal energy storage system that flexibly uses sand-like materials as the storage medium.

By-Product Replaces Virgin Material

The new Sand Battery in Pornainen will be filled with crushed soapstone, a by-product of Tulikivi’s heat-retaining fireplace production. A total of 2,000 tons of soapstone will be used in the Sand Battery, equivalent to the weight of about a thousand soapstone fireplaces. The filling process was completed at the end of October.

“We’re very pleased to use a by-product of Tulikivi’s production instead of virgin materials for the Sand Battery, supporting the principles of circular economy. We have high expectations for soapstone’s performance,” says Polar Night Energy CEO Tommi Eronen.

New Solutions for Circular Economy

Soapstone is a traditional Finnish material, found mainly in regions of North Karelia and Kainuu. Known for its relatively high thermal conductivity, soapstone also has excellent heat storage capacity, outperforming many other types of rock. Research by the two companies has confirmed that crushed soapstone is well-suited for use in Loviisan Lämpö’s Sand Battery.

“The principles of the circular economy challenge the mining industry to seek new solutions. For instance, we’ve started using recycled ceramics in some of our new fireplaces. This innovative Sand Battery cooperation is one example of the fresh thinking we need more of,” says Heikki Vauhkonen, CEO of Tulikivi.

Less Combustion

Forty truckloads of crushed soapstone were delivered to the site. Going forward, the Sand Battery will not require fuel transport, as it operates fully on electricity. The Sand Battery is charged with clean, low-cost electricity.

“The Sand Battery will significantly reduce the combustion-based energy used in our district heating network, and the collaboration with Tulikivi has added a valuable circular economy aspect to this project,” says Loviisan Lämpö CEO Mikko Paajanen.

“The filling process went even better than we expected, and everything was completed on schedule. We implemented some unique solutions to accommodate the material properties and learned a lot in the process. Working with Tulikivi has been a very positive experience,” says Tommi Eronen.

Testing Begins This Winter

The Sand Battery will serve as the primary production unit for the Pornainen district heating network, with a power output of 1 MW and a storage capacity of 100 MWh. The Sand Battery will stand about 13 meters high and 15 meters wide. The project has received support from Business Finland’s new technology energy aid.

The next project phase includes various installation works. Testing of the Sand Battery will begin during the winter, with commissioning set for 2025.

About the companies

Tulikivi is the market leader in heat retaining fireplaces in the world. Tulikivi was born by combining Finnish knowledge of arctic conditions, wood heating know-how and a unique soapstone reserve.

Polar Night Energy is a Finnish startup that designs and manufactures high temperature thermal energy storages for wind and solar energy. The Sand Battery developed by the company enables a significant increase in wind and solar energy production while reducing the use of fossil fuels. The company was founded in 2018.

Loviisan Lämpö is a Finnish district heating company that supplies district heating to its customers in Loviisa, Pukkila, Pornainen, Pyhtää Siltakylä, Pyhtää village center, and Lappohja. Loviisan Lämpö is owned by CapMan Infra.

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