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This is the world’s largest sand battery

This video is part of: Centre for Energy and Materials

It’s filled with 2,000 tonnes of crushed soapstone, standing 13 metres tall and 15 metres wide. The battery stores 100MWh of energy, enough to heat an entire town centre. A sand battery is a ‘thermal energy storage system’. It stores clean energy as heat By baking the sand to high temperatures. the energy can be released when it’s needed, to heat homes and power factories

The world’s largest sand battery has been installed in Pornainen, Finland. Built by start-up Polar Night Energy, it stands 13 metres tall and 15 metres wide, filled with 2,000 tonnes of crushed soapstone. This thermal energy storage system can hold 100 megawatt-hours of heat—enough to warm the town centre.

How the sand battery works

The system stores clean energy by heating sand to high temperatures. When needed, the energy is released to heat homes and power local industry. This new battery is 10 times larger than Polar Night Energy’s first prototype, built in 2022.

Cutting emissions with clean heating

The battery will help reduce Pornainen’s heating emissions by 70 percent by replacing oil and wood chips. In summer, it can meet a month’s heat demand, and in winter, it can last a week. Throughout the year, it provides consistent clean heating, supported by a biomass boiler during peak periods.

A model for the global energy transition

The project supports Finland’s strong performance in clean energy. Ranked second in the World Economic Forum’s Energy Transition Index, Finland leads in energy security, sustainability, and equity. The Forum’s Clean Power, Grids and Electrification programme supports such innovations worldwide.

Watch the video to see how sand is being used to power the clean energy future.