Finland Launches Word’s Largest Commercial Sand battery to Store 100 MWh Renewable Energy
Finland has commissioned the world’s largest commercial sand battery to store renewable energy as heat. The system was developed by Polar Night Energy and is operating in the town of Pornainen. It stores thermal energy instead of electricity, helping provide low-carbon district heating throughout the year.
The battery uses around 2,000 tonnes of crushed soapstone, a sand-like byproduct from fireplace manufacturing. Surplus electricity from wind and solar farms powers electric heaters that raise the material’s temperature to several hundred degrees Celsius. The stored heat can remain available for weeks or even months with minimal losses.
Unlike lithium-ion batteries, the system does not store electricity directly. It stores thermal energy that can later be released for district heating or industrial processes. The storage medium is non-toxic, inexpensive, and designed to operate for more than 30 years.
The commercial-scale battery delivers 1 MW of thermal power and stores up to 100 MWh of heat. It is about ten times larger than Polar Night Energy’s first commercial sand battery launched in 2022. During summer, it can supply nearly one month’s heating demand, while in winter it can provide about a week’s worth of heat.
After one year of operation, the project has achieved its environmental goals. Climate emissions from Pornainen’s district heating network have fallen by about 70%. Oil use for heating has been completely eliminated, while wood-chip consumption has dropped by around 60%. The system has also maintained 100% district heating reliability.
The sand battery also helps stabilize the electricity grid. It absorbs excess renewable electricity when production is high and demand is low. This allows more wind and solar energy to be utilized instead of being curtailed, improving the flexibility of renewable energy systems.
Polar Night Energy believes thermal storage will become an important part of the clean energy transition. The company is already developing larger and more advanced systems, including technologies that could eventually convert stored heat back into electricity. The success of the Pornainen project shows that long-duration thermal storage can complement batteries and reduce fossil fuel use on a large scale.
Sources:
- Polar Night Energy
- Thisis FINLAND
- Live Science
- CNBC
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