World's First Commercial Sand Battery Begins Energy Storage In Finland

Polar Night Energy says it's just opened its first commercial sand battery at the premises of "new energy" company Vatajankoski, a few hours out of Helsinki. New Atlas reports: This is a thermal energy storage system, effectively built around a big, insulated steel tank -- around 4 meters (13.1 ft) wide and 7 meters (23 ft) high -- full of plain old sand. When this sand is heated up, using a simple heat exchanger buried in the middle of it, this device is capable of storing an impressive 8 megawatt-hours of energy, at a nominal power rating of 100 kW, with the sand heated to somewhere around 500-600 degrees Celsius (932-1112F). When it's needed, the energy is extracted again as heat in the same way. Vatajankowski is using this stored heat, in conjunction with excess heat from its own data servers, to feed the local district heating system, which uses piped water to transmit heat around the area. It can then be used to heat buildings, or swimming pools, or in industrial processes, or in any other situation that requires heat. This helps make it extremely efficient, the company tells Disruptive Investing in a video interview. "It's really easy to convert electricity into heat," says Polar Night CTO Markku Ylonen. "But going back from heat to electricity, that's where you need turbines and more complex things. As long as we're just using the heat as heat, it stays really simple." The company claims an efficiency factor up to 99 percent, a capability to store heat with minimal loss for months on end, and a lifespan in the decades. There's nothing special about the sand -- the company says it just needs to be dry and free from combustible debris. [...] The company says it'll scale up, too, with installations around 20 gigawatt-hours of energy storage making hundreds of megawatts of nominal power, and the sand heated as far as 1,000C (1,832F) in certain designs. It's possible to create bulk underground storage facilities out of disused mine shafts, if they're the right shape. There are no high-pressure vessels needed, and the biggest cost involved is often the pipework.

Read more of this story at Slashdot.