The town of Pornainen officially opened an industrial sand battery this week, replacing an old wood-chip power plant and providing heating for the entire municipality. The new system is capable of reducing carbon emissions from the local district heating grid by 70% and is the largest of its kind in the world.
Developed by Finnish company Polar Night Energy, the battery is about 13 meters high and 15 meters in diameter. It stores up to 100 MWh of thermal energy with a 90% cycle efficiency, which is about ten times more than the world’s first commercial sand battery. That’s enough energy to heat the town for a whole week.
The device works by accumulating excess energy from renewable sources – wind and sun. Using a system of air ducts, sand is heated to 600°C and retains heat for a long time. Cold air then passes through the sand, is heated and is used to heat water in the central heating network or for industrial processes.
The company already states that the battery has been operating since June and has exceeded the efficiency targets in the first stages. Currently, many buildings in the city are heated with its help, including the city hall.
The project demonstrates the possibilities of a new approach to storing thermal energy and can become an example for other municipalities in regions with similar climate conditions and energy sources striving for carbon neutrality.
