Finland expedites energy transition through sand-based batteries
Polar Night Energy's Sand Battery Revolutionizes District Heating in Finland
A small Finnish startup, Polar Night Energy, has made a significant stride in the global transition to renewable energy with its innovative sand battery. The company's CEO and co-founder, Tommi Eronen, 33, is leading the charge in developing a thermal energy storage system that promises to store and release large amounts of heat for district heating.
The sand battery, a 4-meter by 7-meter structure filled with 100 tons of sand, is located in the town of Kankaanpää, 270 kilometers northwest of Helsinki, and has a population of 13,000. This groundbreaking technology was launched last year by Polar Night Energy, marking the first time a company has commercially launched sand batteries.
The utility responsible for the collaboration in the realization of the sand battery is Vatajankoski. The sand battery in Kankaanpää uses heated sand (crushed soapstone) to store and release heat, providing a sustainable alternative to traditional district heating methods that rely on fossil fuels such as oil and wood chips.
Polar Night Energy's innovation lies in its ability to heat the sand to 500-600°C using surplus renewable electricity. This stored heat can provide up to 100 megawatt-hours of heat that can be released on demand to warm homes and power local industry, especially during cold periods.
Key aspects of the innovation include the use of abundant, low-cost, and durable material (sand/soapstone) to store heat instead of chemical batteries, long-duration heat storage capability, a large-scale design, decarbonization potential, and high efficiency and durability.
The crushed soapstone has excellent heat retention, losing only 10-15% of thermal energy between storage and recovery. The system's long-duration heat storage capability can last weeks or even months, enabling energy to be stored when renewable supply exceeds demand and used when heating demand peaks, such as in winter.
The world's largest sand battery is an insulated silo 13 meters tall and 15 meters wide, holding roughly 2,000 tonnes of sand—enough to heat an entire Finnish town for weeks. This large-scale design makes it a viable solution for cold climates where district heating is essential.
By replacing fossil fuel-based district heating with this clean thermal storage, the system cuts emissions by about 70% in local heating networks. The system's high efficiency and durability, with minimal loss and virtually no material degradation over time, make it a cost-effective, long-lasting alternative to chemical batteries.
The transition to renewables is happening globally, including in Italy, where innovative energy storage systems using molten salt or CO2 are gaining traction. These energy storage systems, like those developed by Polar Night Energy, are part of the solution for the renewable energy transition, aimed at reducing dependence on fossil fuels.
- The sand battery developed by Polar Night Energy, a Finnish startup, is revolutionizing district heating, offering a sustainable alternative to traditional methods reliant on fossil fuels like oil and wood chips.
- Polar Night Energy's innovation lies in its ability to heat sand to high temperatures using surplus renewable electricity, which can provide a significant amount of heat for district heating during cold periods.
- The sand battery's use of abundant, low-cost, and durable materials, such as sand and soapstone, for heat storage instead of chemical batteries, along with its long-duration heat storage capability, makes it a cost-effective, long-lasting alternative.
- The global transition to renewable energy is ongoing, with innovative energy storage systems being developed worldwide, such as those using molten salt or CO2, to reduce dependence on fossil fuels and combat climate change.
