Finnish telcom operator Elisa to optimize 100 MWh sand battery

Touted as the world’s biggest project of the kind, the sand battery developed by the Tampere-based company Polar Night Energy will use crushed soapstone, a by-product from a fireplace manufacturer, as its storage medium.
The Sand Battery will stand about 13 meters high and 15 meters wide. | Image: Polar Night Energy

Finish telcom operator Elisa has been selected to provide optimization services for a landmark 1 MW/100 MWh thermal energy sand-based storage system developed by Tampere-based startup Polar Night Energy in the municipality of Pornainen in southern Finland.

Elisa’s AI-powered solution will optimize the Sand Battery’s charging and participation in the electricity reserve markets managed by the Finnish transmission system operator, Fingrid. It will, thereby, optimize savings and revenue for Loviisan Lämpö, a Finnish district heating company which will integrate the project into its network.

“Electricity markets have changed, and nowadays, price fluctuations are rapid, and electricity trading takes place in several marketplaces. It is no longer possible for humans to manage this complex system alone. We have developed our own AI-based optimisation technology that we are continuously developing to match developments in the changing electricity markets”, says Ville Väre, director of business development at Elisa.

Once in operation, the Sand Battery will be capable of storing up to 100 MWh of thermal energy – a capacity equivalent to almost one month of heating demand in the summer and one week of demand in Pornainen in the winter. Polar Night Energy said its Sand Battery works as a high-power, high-capacity reservoir for excess wind and solar energy, storing energy in sand as heat.

The facility 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 2024.

Construction work is still underway, and the project will be commissioned in early summer. Currently, electrical, piping and equipment installation work is being carried out, and testing will begin in the spring.

According to Polar Night, the Sand Battery will enable a significant increase in wind and solar energy production while reducing the use of fossil fuels. Its large storage capacity allows for optimised electricity use over timescales of several days or even several weeks.

The Pornainen facility is not the first such project for Polar Night. In 2022, the company switched on the world’s first commercial sand-based, high-temperature heat storage system in the Finnish city of Kankaanpää, with 100 kW of power output and 8 MWh of storage capacity. In December 2023, it announced a partnership with Nordic energy company Ilmatar to develop its sand battery with power-to-heat-to-power capabilities.

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  • Marija has years of experience in a news agency environment and writing for print and online publications. She took over as the editor of pv magazine Australia in 2018 and helped establish its online presence over a two-year period.

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