Finnish researchers have installed the first fully operational “sand battery”capable of storing green energy for months and ensuring a continuous supply throughout the year.
The device uses low quality sand which is heated with inexpensive electricity generated by solar or wind power. Sand stores heat at around 500°C, which can then be used to heat homes during the cold season when energy is more expensive.
Heat at 500°C for months
Finnish politicians and citizens are concerned regarding possible shortages of heat and light, especially during the long cold winter period. According to the BBC, Finland imports most of the gas it consumes from Russiaand the war in Ukraine has intensified interest in viable alternatives. Moscow recently suspended the supply of gas and electricity to the Nordic country due to its application for NATO membership.
In this context, the initiative of the company Polar Night Energy was born from the installation of the first commercial system with a sand battery in Kankaanpää, a town in the west of the Finland. The new design was installed at the Vatajankoski power plant, which supplies electricity to the local district.
The process begins with inexpensively generated electricity used to heat the sand to a temperature of up to 500°C by resistance (the same process used in electric heaters). A current of warm air circulates through the sand, which loses heat very slowly and is a very efficient means of storing it.
Engineers say their battery can keep sand at around 500°C for months.
When energy prices rise, the battery can release high temperature air to heat the water of the district heating systemwhich in turn heats homes and offices.
“It’s very simple, but we liked the idea of trying something new, of being the first in the world to do it,” said Pekka Passi, director of the Vatajankoski plant.
New challenges
One of the biggest challenges now will be to scale this technology and use it for electricity and heat.
The efficiency of the system drops significantly when used to supply electricity to the grid. However, storing green energy in the form of heat can also be an opportunity for the industrial sectorwhere the heat used in the production of food, beverages, textiles or medicine comes from the combustion of fossil fuels.
