Finland Unveils World’s Largest Sand-Based Battery

Finland has activated the world’s largest sand-based battery, a groundbreaking thermal energy storage system that uses crushed rock to store heat. The 2,000 metric tons of pulverized soapstone, stored in an insulated silo, can retain 1,000 megawatt-hours of heat for weeks. This innovation, developed by Polar Night Energy, slashes carbon emissions and reduces reliance on costly oil for the town’s district heating system.
The battery heats sand using electricity, often from renewable sources, and recovers the stored heat with minimal loss (10-15%). It can supply a week’s worth of heating for Pornainen during Finland’s harsh winters. The system also cuts wood chip consumption by 60% and could generate electricity, though at a slight efficiency cost.
Thermal batteries are gaining traction as renewable energy costs decline. Competitors like Scotland-based Sunamp and Electrified Thermal Solutions are exploring similar technologies, with some achieving temperatures up to 2,400°C. Finland’s grid, dominated by renewables (43%) and nuclear (26%), ensures clean and cheap power for the battery.
While Polar Night hasn’t disclosed costs, the raw materials are inexpensive, and the structure is simple. Earlier prototypes cost around $25 per kilowatt-hour of storage, far cheaper than lithium-ion batteries ($115 per kilowatt-hour). This project exemplifies how innovative energy storage solutions can accelerate the transition to cleaner, more sustainable systems.

Published: 6/17/2025