The Finnish city of Pornainen has launched an industrial sand battery capable of completely replacing an old wood-fired boiler house for municipal heating. This development, believed to be the largest in the world, could reduce carbon emissions from the local heating system by up to 70%.
Manufactured by Polar Night Energy, the battery has a capacity of 100 MWh. At 13 meters tall and 15 meters in diameter, it is approximately 10 times larger than the original model. The sand battery can store enough heat to heat the entire city for a week, achieving a "recycled" efficiency of 90%.
The system works simply: Excess energy from wind and solar power is heated to 600°C by a closed duct system. Cool air then passes through the sand, absorbing the heat, which is then used to heat water or steam for industrial use.
Direct electricity generation is not currently envisioned, but the company is developing a system to convert heat into electricity via a steam turbine. The battery has been operational since June and has exceeded expected efficiency levels. It will be a key tool in Pornainen's journey towards carbon neutrality in the coming years.
