This "Sand" Battery Stores Heat as a Form of Clean Energy
A Finnish company has developed a unique renewable energy storage solution that employs sand rather than lithium-ion or other battery technology.
Polar Night Energy and Vatajankoski, an energy utility in Western Finland, have developed a technique for storing electricity as heat in the sand. While other institutions, such as the US National Renewable Energy Laboratory, are studying the use of sand for energy storage, the Finns claim theirs is the first completely functional commercial installation of a sand-based battery.
Similar to conventional renewable energy storage systems, Polar's technology stores excess energy from wind turbines and solar panels. Specifically, it stores energy in the form of heat, which is then utilised by the district heating network that Vatajankoski provides.
Sand is inexpensive and highly efficient in storing heat at temperatures between 500 and 600 degrees Celsius. Polar claims that its method can keep sand "hotter than the stoves in standard saunas" for months until the heat is needed during Finland's long winters.
The process of resistive heating used to warm the sand creates and circulates hot air within the building. When it comes time to use the stored energy, the battery transfers the heated air to warm water in the district's heating system, which is then pumped to homes, offices, and even swimming pools. Currently, Polar's sand battery serves only a single city, and it is unknown whether the technology can be expanded.
Source: Engadget
