With cheap raw materials, scientists create equipment capable of storing energy generated by the sun and wind
Store the energy produced from the sun and wind is one of the biggest challenges to better exploit renewable sources. The good news is that a company from Finland claims to have found an economical solution: a gigantic battery that stores this production in the form of heat to be distributed later, reports the BBC.
The peculiarity of this battery is that it uses construction sand instead of lithium, a more expensive raw material with a significant environmental footprint. To give you an idea of the size, each unit holds one hundred tons of sand.
The first commercial installation of this sustainable battery was carried out in the city of Kankaanpää, in the western region of the Nordic country. It is connected to the Vatajankoski power plant, responsible for the city's heating system.
“It seems strange, but sand is easy to obtain, it is cheap and you can reach high temperatures, around 500°C, while with water you can only reach 100°C. That’s a lot of heat stored in a small space,” Pekka Passi, managing director of the Vatajankoski plant, told the British network.
From generation to storage
In this new model, after renewable energy is generated, part of it enters the local distribution network while the rest goes to the battery. There, this electricity is used to heat the sand using resistive heating (the same logic that makes electric stoves work).
This results in hot air, which circulates through the sand through a heat exchanger — anyone who has ever had the displeasure of burning the sole of their foot on the beach sand is well aware of its potential to store heat. According to the developers of the idea, the sand battery can maintain a temperature of 500ºC for a few months.
This way, surplus clean energy can be used when sun or wind are scarce (or in winter, when electricity costs rise). At this time, the battery releases the stored hot air to be used in the city's heating system and provide hot water for homes, offices and other urban spaces.
The next challenges of this innovation are to expand its offer to more cities and to be able to store energy, to increase the possibilities of use beyond water heating. According to the BBC, the efficiency of the system “drops dramatically” when sand is used to return energy to the electricity grid.
