Finnish ‘sand battery’ can store energy for months

Polar Night Energy's silo containing the sand battery
Image: Polar Night Energy

Researchers in Finland have installed the world’s first operational ‘sand battery’, which can store power from renewable sources for months at a time, according to Fast Company.

In the city of Tampere in western Finland, a pump pushes hot air into a large container filled with building sand.

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The device, which contains 100 tons of low-quality sand, is filled with heat made from cheap electricity from the sun or wind. This coarse, ready-to-use grain is highly effective at retaining heat, keeping it at extremely high temperatures for months.

The sand battery aims to address one of the biggest challenges facing renewable energy—what do you do when the wind isn’t blowing and the sun isn’t shining?

The sand battery’s developer, Polar Night Energy, said the new technology could solve energy supply problems all year round.

At factories, the sand batteries could help store heat for industrial processes that require high temperatures and currently run on fossil fuels. The sand can be heated to 400 degrees Celsius, and with some tweaks to the pipes and other materials in the system, it could store and provide heat up to 700 or 800 degrees Celsius.

The basic approach is simple. Inside a strong container—either a silo with extra-thick walls, or an underground space, potentially built in an old mine—a giant pile of sand can be heated with hot air blowing through pipes. When the sand is extremely hot, it naturally retains the heat until it’s ready for use.

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Sand is an ideal material for the purpose, as it’s available everywhere and is cheap.

Read the full story here.

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