While Elon Was Busy Elsewhere, Finland Invented a Sand Battery
Spoiler alert, the sand battery will not power your cel-phone, computer, or electric car.
What it will do, is power up your home, business, community, or electric grid from renewables when the sun is not shining, and that’s huge.
If this seems like a promo for Polar Night Energy, it is I guess, but why not? When the Russians threatened Finland with an energy cut, for joining NATO, the Finns thought their way out of a tight corner. They needed self-sufficiency, and they needed it fast, with winter coming on. Finnish founders, Tommi Eronen and Markku Ylönen, engineered the technology.
“We were talking about how - if we had the liberty to design a community for ourselves - how could we solve the energy problem in such a confined environment?” Markku said of the inspiration behind Polar Night Energy in 2018. “Then quite quickly, especially here in the north, you run into the problem of energy storage if you're trying to produce the energy as cleanly as possible.
“The friends started playing around with ideas, landing on sand as an affordable way to store the plentiful electricity generated when the sun is shining, or the wind blowing at a high rate. The industrial-scale solution from Polar Night Energy is now the primary production plant for the network.”
Keep in mind that, in Finland, winter comes early, daylight is short, and temperatures are brutal.
“Finding a way to store wind and solar renewables is the crux of unleashing their full potential. Lithium batteries work well for specific applications,” explains Markku, “but aside from their environmental issues and expense, they cannot take in a huge amount of energy. Grains of sand, it turns out, are surprisingly roomy when it comes to energy storage.”
It’s quite a simple structure to begin with, Polar Night Energy said of its prototype.
A tall tower is filled with low-grade sand and charged up with the heat from excess solar and wind electricity. This works by a process called resistive heating, whereby heat is generated through the friction created when an electrical current passes through any material that is not a superconductor. The hot air is then circulated in the container through a heat exchanger. The sand can store heat at around 500C for several days to even months, providing a valuable store of cheaper energy during the winter. When needed, the battery discharges the hot air - warming water in the district heating network. Homes, offices and even the local swimming pool all benefit.
“There’s really nothing fancy there,” Markku says of the storage. “The complex part happens on the computer; we need to know how the energy, or heat, moves inside the storage, so that we know all the time how much is available and at what rate we can discharge and recharge.”
Having refined its charging algorithms, Polar Night Energy has now successfully scaled up the storage tech in Pornainen (population 5000).
“This project has gone very smoothly," says Mayor of Pornainen, Antti Kuusela. “Many of the town's buildings, including the comprehensive school, town hall, and library, rely on district heating. Pornainen wants to be a front runner in sustainable energy solutions, and we welcome all innovations that support that goal. One of the key targets in our municipal strategy is carbon neutrality, and the sand battery plays an important role in achieving it."
In total, the sand battery is expected to knock off 160 tons of carbon dioxide equivalent emissions per year. Not bad for a village of 5,000. Scale that up to cities across the world, and you have a game-changer.
The battery’s thermal energy storage capacity equates to almost one month’s heat demand in summer and a one-week demand in winter in Pornainen, Polar Night Energy says.
Obviously, this is a worldwide solution for the problem of what to do when the sun goes down with solar. But, aside from that, think of the areas of the world where both sand and sunlight are plentiful. North Africa, and the Middle East come to mind, as well as huge areas of Australia, China and Russia.
Just some news to cheer up your day.
You’re welcome.