A small Finnish town, Pornainen, is now heated by the world’s largest “sand battery.” Engineered by Polar Night Energy, this massive thermal energy storage system stores heat, not electricity, and runs on surplus renewable energy, tells this interesting article on the Live Science website.
Electricity from solar panels, wind turbines, or the grid heats up crushed soapstone sand to a blistering 600°C inside a 13-meter-tall steel silo. The heat is stored and later extracted by blowing air through the sand, producing hot water, steam, or warm air for district heating. The system delivers around 1 MW of thermal power, with a total storage capacity of 100 MWh, enough to cover a month’s heat demand in summer and roughly a week in winter.
Replacing oil entirely and cutting wood-chip use by 60%, the sand battery reduces Pornainen’s heating-related CO₂ emissions by about 70% (around 160 tons annually). That aligns with Finland’s push for carbon neutrality by 2035 and showcases how clean heating solutions can drive the energy transition.
Uses of this research and technology:
- District heating across communities where seasonal heating demand is high.
- Industrial heat applications, especially where temperatures above 100°C are needed; sand batteries can supply hot air or steam directly.
- Grid balancing and storage, capturing excess or off-peak renewable electricity and releasing it when demand spikes.
- Scaling potential: sand is cheap, plentiful, and often sourced as an industrial by-product, making larger installations feasible and economical.
The sand battery turns variable renewables into dependable heat; no combustion, no batteries, just the natural retention of warmth in sand.