The sand battery sits inside a four-meter wide and seven-meter high grey silo. (Image Credit: Polar Night Energy)
Researchers have been trying to come up with efficient long-term energy storage alternatives now that renewables are becoming essential. Typically, batteries consist of lithium and other minerals that can serve as energy farms, making it unsustainable if the world transitions to renewables. Polar Night Energy researchers recently installed the first commercial-scale “sand battery” that stores energy produced from renewables. This could lead to a long-term solution for ongoing year-round supply issues.
For fourteen years, Switzerland worked on turning its reservoirs into massive water batteries. However, these cost millions of dollars to build even though it relies on a very old concept for higher-level energy storage. Finland’s latest development could be a more affordable solution.
So how does the sand battery work? Whenever renewable sources generate extra power that exceeds the capacity, it distributes that energy to the sand battery. Rather than transferring electrons from an electrode or transferring water to a higher reservoir with power pumps, a sand battery relies on resistive heating to boost the air’s temperature. Afterward, a heat exchanger transfers the air to sand.
An excess pile of sand from the heat storage. (Image Credit: Polar Night Energy)
Since sand melts at hundreds of degrees Celsius, a sand tower can store energy for months at a time, providing a sustainable long-term solution. So far, the Polar Night Energy researchers have deployed the first commercially-scaled sand battery in Kankaanpää, western Finland. A hundred tonnes of sand commonly used for construction sits inside a tall grey silo. This approach is a more affordable option compared to batteries with lithium, cobalt, and nickel.
The sand battery provides power for the district’s central heating system. As energy prices rise, the battery’s hot air can warm up the water and supply energy to homes and offices in the area. However, transforming the heat back into energy isn’t an energy-efficient process. This technology can be very useful in many industries, even if it just stores heat.
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