A company in Finland has created an unusual renewable energy storage solution: one that uses sand instead of lithium-ion or other battery technologies. Polar Night Energy and Vatajankoski, a power company in western Finland, have built a storage system that can store electricity as heat in the sand. While there are other organizations exploring the use of sand for energy storage, including the US National Renewable Energy Laboratory, the Finns say theirs is the first fully operational commercial sand battery installation.
Similar to traditional renewable energy storage systems, Polar’s technology stores energy from wind turbines and solar panels that is not used immediately. More specifically, it stores energy as heat, which is then used for the district heating network that supplies Vatajankoski. Sand is inexpensive and retains heat very effectively at around 500 to 600 degrees Celsius. Polar says its technology can keep the sand “hotter than the ovens in typical saunas” for months, until it’s time to harness that heat during Finland’s long winters.
As the BBC explained, the resistance heating process used to heat the sand creates hot air that circulates within the structure. When it’s time to use the stored energy, the battery discharges this heated air into warm water in the district’s heating system, which is then pumped to homes, offices and even swimming pools. At the moment, Polar’s sand battery only powers a single city, and it’s unclear if the technology can scale. That BBC also says its efficiency “drops dramatically” when it comes to feeding power to the grid instead. However, the technology is still in its infancy and other companies and organizations could find solutions to these problems.
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https://www.engadget.com/sand-battery-stores-renewable-energy-as-heat-124512914.html?src=rss This ‘sand’ battery stores renewable energy as heat