Finland is pioneering a new way to store renewable energy with the world’s largest sand battery. Located in Pornainen, this innovative system stores 100 MWh of thermal energy using crushed soapstone. The battery supplies heat to the local district network, reducing fossil fuel use and slashing emissions nearly 70%. This breakthrough could reshape how communities manage clean energy.
What’s Happening & Why This Matters
The sand battery, developed by Finnish company Polar Night Energy, replaces oil and wood chips in Pornainen’s district heating system. The CEO of the district heating network, Mikko Paajanen, says, “Our goal is climate neutrality by 2035, and the sand battery is a major step toward that.”
This industrial-scale battery uses excess wind and solar power to heat sand inside a large container. The heat can be stored at around 500°C for days or even months, providing a reliable source of warmth when renewable generation is low. During winter, the stored heat powers the district system, supplying homes, schools, and public facilities.
This facility is about ten times larger than Polar Night Energy’s earlier prototype installed in Kankaanpää in 2022. That pilot project was a timely solution after Russia cut gas supplies amid Finland’s NATO membership.
Polar Night Energy’s founders, Tommi Eronen and Markku Ylönen, developed the concept while seeking a way to store clean energy efficiently in northern climates. They realized that sand is an affordable and practical storage medium, with much higher capacity than conventional lithium batteries.
The battery’s structure is simple but effective. A tower is filled with low-grade sand heated by electric resistive heating — a process that generates friction from the electrical current passing through the sand. Hot air circulates through a heat exchanger, transferring thermal energy to water in the district heating network.
Choosing the right sand material was crucial. The company uses crushed soapstone sourced from Finnish manufacturer Tulikivi, a traditional producer of heat-retaining fireplaces. This sustainable choice supports a circular economy and limits environmental impact.
Mayor Antti Kuusela of Pornainen welcomes the project: “Our municipality aims to lead in sustainable energy. The sand battery plays an important role in cutting emissions and achieving our carbon neutrality targets.”
The battery reduces carbon dioxide emissions by about 160 tonnes per year in Pornainen. Its storage capacity equals nearly one month’s heat demand in summer and one week’s in winter.
Polar Night Energy plans to expand its technology globally, aiming to build much larger installations. The company is also piloting methods to convert stored thermal energy back into electricity, thereby extending the potential uses.
TF Summary: What’s Next
Finland’s sand battery demonstrates a practical, scalable way to store renewable energy and reduce carbon emissions in heating systems. Utilizing abundant, sustainable materials, the technology has the potential to revolutionize energy storage worldwide.
As Polar Night Energy develops larger projects and explores electricity generation, this innovation positions Finland at the forefront of green energy solutions.
— Text-to-Speech (TTS) provided by gspeech