Many countries are seeing energy prices soaring, and sensible governments are pouring investment into renewable energy generation. While wind, solar, and hydroelectric power can theoretically create almost unlimited energy, the world’s capacity to store it is sorely lagging behind, and research into battery technology has become imperative to solving our energy needs.  

Wild ideas have ranged from massive CO₂ bladders that produce on-demand power by being forced through turbines, to enormous weights that store kinetic energy until being dropped.  

Now, though, a new idea has been proposed – a sand battery. Storing energy as heat in a massive vat of sand, the battery holds excess energy created by wind and solar, to then be discharged in times of need by using that heat for various applications. It could store a massive 8 megawatt hours of energy and discharges around 200 kilowatts of power when full, and can store the energy for months. 

“Its main purpose is to work as a high-power and high-capacity reservoir for excess wind and solar energy. The energy is stored as heat, which can be used to heat homes, or to provide hot steam and high temperature process heat to industries that are often fossil-fuel dependent,” write Polar Night Energy in a statement. 

Storing energy as heat is not a new idea, but storing it in sand could be quite an efficient solution. Sand has a significantly higher boiling point and can store far more energy than a water tank of similar size, and is only limited to the construction materials of the battery and not the temperature limit of sand, according to Popular Mechanics.  

Polar Night already has a large sand battery built in a small town called Kankaanpää in western Finland, where it helps heat homes and a local swimming pool. Standing at 7 meters (23 feet) tall, the battery contains 110 tons of sand in a large container that charges while energy is cheap and abundant. When needed, air flows through pipes that travel close to the sand and gets heated, where it can then go off to either provide heating or heat water into steam to power a turbine. It is more efficient if the heat isn’t transferred back to electricity, but the option is there. 

The company hopes that the battery can form part of the ambitious strategy to increase renewables use, ensuring every watt is used or stored. New and innovative forms of batteries will be desperately needed as the world produces more renewable energy, so a cheap solution using just sand could be an ideal option.