Startup Polar Night Energy builds the world's largest sand battery

The sand battery designed by startup Polar Night Energy will be built over the next 13 months in Pornainen, Finland to meet year-round heating demand.

Polar Night Energy is building the world's largest sand battery in Finland. (Photo: BBC).

Once built, the company estimates the new battery could help reduce annual carbon dioxide emissions by 70%. The new sand battery is a 13m high, 15m wide barrel filled with crushed soapstone (which conducts heat better than regular sand) and heat transfer tubes. According to the plan, when there is excess energy from wind and solar power, a process called resistive heating will be used to convert it into heat, IFL Science reported on March 11.

The process heats the air, then circulates it through the barrel using a heat transfer pipe, warming the surrounding crushed soapstone. When conventional energy sources become expensive, as in the winter months, hot air can be fed into the district-wide heating system.

The sand battery under construction in Pornainen is not the first version. Previously, Polar Night Energy installed the world's first fully operational commercial sand battery in Kankaanpää, Finland, in 2022. However, the latest version will be 10 times larger, with a heating capacity one megawatt and the ability to store up to 100 megawatts of thermal energy, enough to meet the district's heat needs for a week in winter and nearly a month in summer.

While the world is looking to increase renewable energy storage capacity with many expensive and environmentally harmful solutions, sand batteries like the above could become a cheap and low-impact solution , according to Polar Night Energy. . In addition to the sand battery project, Finland is also preparing to turn an abandoned mine into a giant gravity battery.