Finland Powers Up World’s Largest Sand Battery with Promising Economics

It may not look like much, but Finland has just powered up the world’s largest sand battery—a massive 49-foot silo filled with 2,000 metric tons of crushed rock.

Yes, actual sand.

This type of thermal energy storage system works by using electricity—often from renewable sources—to heat sand or crushed rock. The stored heat can then be used for purposes like heating buildings.

What makes it even more appealing is the low cost. The system uses crushed soapstone, a waste product from a local fireplace manufacturer, now stored inside an insulated silo in the small town of Pornainen.

Sand Battery Set to Cut Emissions and Heating Costs

While it may not be as eye-catching as a massive lithium-ion battery pack, the 2,000 metric tons of crushed rock inside the 49-foot-wide silo in Pornainen could significantly cut the town’s carbon emissions by replacing the need for expensive oil used in its district heating system.

Similar to many Scandinavian towns, Pornainen runs a central boiler that distributes hot water to homes and buildings. Built by Finland’s Polar Night Energy, the sand battery stores 1,000 MWh of heat—enough to warm the town for a week in winter. The system is highly efficient, retaining 85%–90% of stored heat, with output temperatures reaching up to 400°C.

The heating network currently burns wood chips, but Polar Night expects the sand battery to cut that use by about 60%. The stored heat can also generate electricity, though the process lowers overall efficiency.

Thermal Battery Innovation Heats Up as Renewables Drive New Solutions

As renewable energy becomes more affordable, thermal batteries are gaining traction. In addition to Polar Night Energy, several startups are exploring this technology. Sunamp, based in Scotland, is developing a battery that uses the same compound found in salt-and-vinegar chips. Electrified Thermal Solutions—TechCrunch’s Startup Battlefield 2023 runner-up—has engineered a special brick capable of reaching nearly 2,000°C. Meanwhile, Fourth Power is creating graphite blocks that store energy as heat up to 2,400°C.

Pornainen’s sand battery charges from the grid when electricity is cheapest. With Finland’s power mix mostly clean and prices the lowest in Europe (under €0.08/kWh), the battery benefits from both low-cost and low-carbon energy.

Polar Night hasn’t disclosed the project’s cost, but with cheap materials and a simple design, it’s likely affordable. A smaller prototype previously cost around $25 per kilowatt-hour—far less than lithium-ion batteries at $115.The larger system is likely even more cost-effective.

Read teh original article on:Techcrunch

Read more:Eye Injection Restores Vision in Mice – Human Trials on the Horizon