- Finland has launched the world’s largest sand battery in Pornainen, using 2,000 metric tons of crushed soapstone to store heat for the town’s district heating system.
- The system stores heat at up to 400°C with minimal energy loss (10–15%) and can provide a week’s worth of heating during winter.
- It significantly cuts reliance on oil and wood chips, potentially reducing wood chip use by 60% and lowering heating costs by using Finland’s low-cost, clean electricity.
- The project highlights the growing appeal of thermal energy storage as a low-cost, sustainable alternative to conventional batteries and fossil fuel heating.
A quiet town in southern Finland has become the site of a groundbreaking advancement in clean energy. Pornainen, located about 30 miles northeast of Helsinki, has officially activated the world’s largest sand-based thermal energy storage system.
Designed by Finnish energy startup Polar Night Energy, the innovative project is expected to dramatically reduce the town’s reliance on fossil fuels and cut heating costs while supporting the transition to a more sustainable energy future.
How the Sand Battery Works
At the heart of the system is a massive thermal battery containing 2,000 metric tons of finely crushed soapstone. The sand-like rock, once considered industrial waste from a local fireplace manufacturer, now plays a vital role in storing heat.
Electricity from the national grid is used to heat the sand inside a 49-foot-wide insulated steel silo. The system can reach temperatures of up to 400 degrees Celsius, and once charged, it stores the thermal energy for days or even weeks with minimal loss, only around 10 to 15 percent.
This stored heat is then used to supply the town’s district heating network, which circulates hot water through pipes to warm homes and public buildings. This is a common setup in Nordic countries, but until now, much of that heat was produced by burning oil or wood chips. With the new sand battery in operation, the need for these carbon-emitting fuels is significantly reduced.
Clean, Efficient, and Cost-Effective
One of the major advantages of this system is its simplicity and affordability. The raw materials, primarily discarded soapstone, were virtually free, and the infrastructure required to build the battery is relatively straightforward compared to other energy storage technologies.
While Polar Night Energy has not publicly disclosed the total cost of the Pornainen installation, an earlier, smaller prototype was estimated to cost approximately $ 25 per kilowatt-hour of heat storage.
In comparison, lithium-ion batteries used for electrical energy storage cost around 115 dollars per kilowatt-hour. The cost savings make the sand battery especially attractive for small towns and rural communities looking for low-cost, low-emission heating options.
Reducing Emissions and Enhancing Energy Independence
The environmental impact of the sand battery could be substantial. According to Polar Night Energy, the system is expected to reduce the town’s consumption of wood chips by 60 percent and eliminate its dependence on oil for heating altogether. This marks a significant step toward the town’s goal of achieving carbon neutrality.
Another major benefit is the ability to store energy when electricity prices are at their lowest. Finland currently has the lowest electricity prices in Europe, averaging under 0.08 euros per kilowatt-hour, less than half the EU average. This means the sand battery can be charged during off-peak hours, providing significant cost savings over time.
Additionally, the Finnish energy grid is among the cleanest in the world, with 43 percent coming from renewable sources and another 26 percent from nuclear power. This makes the heat stored in the sand battery not just cost-effective, but also environmentally responsible.
A Growing Field of Innovation
Finland’s sand battery is part of a growing movement to explore new forms of thermal energy storage, driven by the rapid expansion of renewable power sources. Similar technologies are being developed around the world.
In Scotland, a company called Sunamp is building batteries using phase-change materials similar to those found in salt-and-vinegar potato chips. In the United States, Electrified Thermal Solutions has engineered a unique type of brick capable of storing heat at nearly 2,000 degrees Celsius. Another U.S. startup, Fourth Power, is working with graphite blocks that can store heat at temperatures reaching 2,400 degrees Celsius.
While each of these systems uses different materials and reaches different temperatures, the goal is the same: to store excess energy generated by solar panels, wind turbines, or cheap off-peak electricity, and release it when demand is high.
A Model for the Future
Though it may not look like much from the outside, the sand battery in Pornainen represents a turning point in how small communities can embrace energy independence, fight climate change, and lower utility costs.
The simplicity, low cost, and scalability of the system make it an appealing option for similar towns across the Nordic region, and potentially around the world.
Follow TechBSB For More Updates
