Pyhäsalmi Mine is in the heart of Finland on the site of zinc and copper deposits. Miners followed the seams down deep vertical shafts, to depths of over 4,500 feet. The mine is no longer viable and the community is repurposing it. One project will include a giant gravity battery, to store excess energy during periods of surplus generation.
4,500-Foot-Deep Shafts Ideal for Giant Gravity Battery
A gravity battery uses electricity to lift giant weights, using surplus energy during off-peak periods. Then, when demand is high, it harvests the energy in gravity to lower the huge weights. This downward motion rotates a turbine via a system of mechanical gears.
The Pyhäsalmi giant gravity battery will use excess energy, in daytime from wind and solar to lift its heavy weight. When night falls, and the wind drops and the sun sets, it will lower the weight to generate two-megawatts of electricity supply.
“This project will demonstrate at full scale how our technology can offer reliable long-life energy storage,” says the developer. “It can capture and store energy during periods of low demand, and release it rapidly when required.”
Huge Potential For Storing Energy in Disused Mines
The International Institute for Applied Systems Analysis (IIASA) completed a study of the potential of gravity batteries in abandoned mines. The Institute concluded these could generate up to 70 terawatt hours, which they believe would be sufficient to meet global electricity demands.
These projects would also provide a livelihood for local communities seeking alternative employment. The old mines already have grid connections. “This significantly reduces the cost and facilities for the implementation of underground gravity energy storage plants,” according to the IIASA study.
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Preview Image: Schematic of Giant Battery
