A team of Finnish engineers has installed the world’s first commercial "sand battery," and it could help overcome a vexing obstacle to widescale implementation of renewable energy, per the BBC. It couldn’t come at a better time for Finland, since Russia cut both gas and electricity supplies in response to Finland’s bid to join NATO. The country already gets 40% of its energy from biofuels and renewable sources, but solar and wind energy are volatile, especially near the Arctic Circle, making it harder for the country to cut reliance on fossil fuels. Developed by Polar Night Energy, the sand battery resembles a grain silo, and it offers a relatively simple and cheap energy solution in the cold, dark Finnish winter.
Installed at the Vatajankoski power plant in the town of Kankaanpää, the sand battery contains 100 tons of common builders sand, which can efficiently store heat up to 500°C (932°F) for months. During periods of peak sunlight, surplus solar energy can be diverted and stored in the sand, through which hot air is circulated by a heat exchanger. That heat can then be used to supplement other electrical sources to heat water, homes, and even the municipal swimming pool. According to CleanTechnica, this is especially useful in places like Finland where "district heating" is common, as opposed to having separate furnaces and boilers in every building.
One downside for the Polar Night battery is that it is not designed to produce electricity, at least not efficiently. However, here in America, the National Renewable Energy Lab is working on a sand battery that can. The NREL says its ENDURING Mechanism also taps surplus solar or wind energy, but it uses industrial-grade silica sand. Particles are "fed through an array of electric resistive heating elements to heat them to 1,200°C," enabling energy storage up to a "staggering" 26,000MWh, enough to drive turbomachinery and spin generators to produce electricity. (More renewable energy stories.)
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