This Innovative Battery is Made of Sand
Winters are long and cold in Finland. That’s why new technology that stores summer heat in a giant sand battery could be used to keep homes warm and toasty in the winter.
In Kankaanpää in Southwestern Finland, a startup called Polar Night Energy has created a giant sand battery. It actually consists of a tower located at the Vatajankoski power plant that is filled with 100 tons of sand that is super-heated using renewable energy, according to Fast Company.
The sand battery can store the heat for months so energy that was generated by solar power in the summer can be used in the winter to heat homes.
How does it work?
The sand in the tower is charged with heat from excess solar and wind energy in a process called resistive heating, reported Euronews. Heat is actually generated through friction when an electrical current passes through any non-superconductor material like sand.
Then the hot air is circulated in the container via a heat exchange. Sand can store the heat around 500 Celsius for months and warm homes, offices, and even local swimming pools.In fact, the company said that the Kankaanpää’s swimming pool is being heated by the sand battery.
“There’s really nothing fancy there,” Markku Ylönen, cofounder of Polar Night Energy, told Euronews. “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 charge.”
Sand is an ideal material Ylönen told Fast Company because it is cheap and readily available everywhere. While other inexpensive items like water can store heat, sand can be heated to much higher temperatures. The sand used is the lowest quality so it can not be used in construction thus making it a sustainable choice.
Sustainable power
While the first sand battery connects to the electrical grid, the technology can run on solar and wind power. Although it is designed for long-term energy storage from the summer sun, that isn’t actually necessary in Finland because wind power is so abundant.
“With any battery technology or storage technology, the more you use it, the better the economics look like,” Ylönen said. “So an optimal period for us is something like two to three weeks of discharging and charging.”
The system is competitive with the cost of energy produced from natural gas but is planning on building a new silo that is 100 times the size of the one in use. That will make it competitive with the cost of biogas.
At this point, the technology is being proven in Finland but the company wants to spread the technology around the world as quickly as possible. With uncertainty about the availability of gas and rising energy costs, the scaled-up sand battery should be a huge success.
