Finland's Giant Sand Battery Cuts Town's Emissions 70%

A small town in Finland just solved one of renewable energy's biggest problems using something you'd find at the beach.

Pornainen, a community of 5,000 people in southern Finland, now gets most of its heat from the world's largest commercial sand battery. The massive facility stands 13 meters tall and uses 2,000 metric tons of crushed soapstone to store clean energy as heat.

The technology works like a giant thermos. When wind and solar power flood the grid with cheap electricity, the system heats the sand to extremely high temperatures. Heavy insulation traps that heat for days or weeks until the town needs it for heating homes and buildings.

The results speak for themselves. Since launching last year, the sand battery has cut greenhouse gas emissions from Pornainen's heating network by almost 70%. It also reduced wood chip use by 60%.

"We're changing from a world where big power plants were doing the energy production to where solar and wind are producing the energy, then we need a massive amount of storage," said Tommi Eronen, CEO of Polar Night Energy, the company behind the project. The sand battery can cover nearly one month of the town's heating needs in summer and about one week in winter.

The facility represents a leap forward from an earlier version launched in 2022. This new battery is 10 times larger and proves the technology can scale up to serve entire communities.

Annette Höglund-Dönnes, Chief Commercial Officer at Polar Night Energy, compared the process to charging your phone overnight when electricity is cheaper. The battery charges up during times of abundant renewable energy and releases heat when it's most needed and most expensive to produce.

Before the sand battery, Pornainen relied on burning oil and wood chips for heating. Now the town enjoys combustion-free heating for most of the year, with an old wood chip plant standing by only as backup.

The Ripple Effect

Communities on every continent have reached out to Polar Night Energy about replicating the project. Towns still dependent on coal and oil see the sand battery as their path away from fossil fuels.

The technology shines because it doesn't require rare earth materials like lithium-ion batteries do. Sand batteries can store energy for days or weeks, far longer than traditional batteries that max out at two to four hours.

Jan Rosenow, professor of energy and climate policy at the University of Oxford, believes electrothermal storage technologies like sand batteries will spread globally. "You don't need rare earths, critical raw materials and the beauty is you can also charge up the battery when the electricity is cheap and discharge whenever you need the heat," he told CNBC.

The sand battery addresses a common criticism of renewable energy: that solar and wind only work when the sun shines or wind blows. By storing that energy as heat, communities can access clean power even when nature takes a break.

From Finland to the world, sand might just be the missing piece in the clean energy puzzle.