Finnish researchers have installed the world’s first fully working “sand battery” which can store green power for months at a time.
According to BBC, the developers said this could solve the problem of year-round supply, a major issue for green energy. Using low-grade sand, the device is charged up with heat made from cheap electricity from solar or wind. The sand stores the heat at around 500C, which can then warm homes in winter when energy is more expensive.
Concerns over sources of heat and light, especially with the long, cold Finnish winter on the horizon are preoccupying politicians and citizens alike.
But in a corner of a small power plant in western Finland stands a new piece of technology that has the potential to ease some of these worries.
The key element in this device? Around 100 tons of builder's sand, piled high inside a dull grey silo. These rough and ready grains may well represent a simple, cost-effective way of storing power for when it's needed most.
Because of climate change and now thanks to the rapidly rising price of fossil fuels, there's a surge of investment in new renewable energy production.
But while new solar panels and wind turbines can be quickly added to national grids, these extra sources also present huge challenges. The toughest question is about intermittency - how do you keep the lights on when the sun doesn't shine, and the wind doesn't blow?
The most obvious answer to these problems is large scale batteries which can store, and balance energy demands as the grid becomes greener.
Right now, most batteries are made with lithium and are expensive with a large, physical footprint, and can only cope with a limited amount of excess power.
But in the town of Kankaanpää, a team of young Finnish engineers have completed the first commercial installation of a battery made from sand that they believe can solve the storage problem in a low-cost, low impact way.
“Whenever there's like this high surge of available green electricity, we want to be able to get it into the storage really quickly,” Markku Ylönen, one of the two founders of Polar Night Energy who have developed the product, told BBC.
The device has been installed in the Vatajankoski power plant which runs the district heating system for the area. Low-cost electricity warms the sand up to 500C by resistive heating (the same process that makes electric fires work). This generates hot air which is circulated in the sand by means of a heat exchanger.
Sand is a very effective medium for storing heat and loses little over time. The developers say that their device could keep sand at 500C for several months.