Located in the Helsinki Ring of Industry area, the world’s largest thermal battery is in operation. The energy company Loviisan Lämpö, operating in Pornainen, was among the first in the world to utilize the commercial energy storage developed by Polar Night Energy. This new climate technology is unique and environmentally friendly, as it allows the storage of cleanly produced thermal energy.
The basic idea of the sand battery is simple yet ingenious: thermal energy is stored in sand or sand-like material, which can be heated with electricity when production is at its peak. The charging and discharging of the sand battery occur through a patented heat transfer system that circulates air in a closed loop within the storage medium. The stored energy can be used as hot air, water or steam, for example, in district heating networks or industrial processes.
“We use clean and cheap electricity to charge the Sand Battery. Nothing is burned in our process, so there is no need for oil or wood chips. Our technology is particularly well-suited for manufacturing industries that require high temperatures, such as the beverage and food industries,” explains Miika Peltola, Communications Manager at Polar Night Energy.
From Soapstone Fireplaces to Sand Battery
The collaboration in Pornainen began when Loviisan Lämpö was looking for alternatives to upgrade its power plant. The goal was to increase climate-friendly energy production while reducing energy produced by combustion. The Sand Battery is expected to reduce annual CO₂-equivalent emissions from the local heating network by around 160 tons, cutting climate emissions in Pornainen’s district heating by nearly 70 percent.
“This project has gone very smoothly. Pornainen wants to be a front runner in sustainable energy solutions, and we welcome all innovations that support that goal. One of the key targets in our municipal strategy is carbon neutrality, and the Sand Battery plays an important role in achieving it,” says Antti Kuusela, Mayor of Pornainen, in the press release of Polar Night Energy.
The Sand Battery in Pornainen will also participate in Finland’s transmission system operator Fingrid’s reserve markets for additional revenue. This helps maintain grid stability as wind and solar power increase.
The thermal energy storage in Pornainen is filled with crushed soapstone, a by-product from the production of Tulikivi Oyj, a manufacturer of heat-retaining fireplaces. In total, there are about 2,000 tons of soapstone, equivalent to the weight of about a thousand soapstone fireplaces. In addition to sand and soapstone, by-products from mining and the steel industry are also well-suited as storage media, making the sand battery support the circular economy in many ways.
“The sand battery in Pornainen is about ten times larger than the first one, but it is possible to scale the size to meet even greater needs,” says Peltola. The company’s first sand battery was commissioned in Kankaanpää, Western Finland, in 2022.
At the Forefront of Innovation
Finland is known as a stable and safe country that offers excellent conditions for innovation and sustainable development. “Finland offers a stable and safe environment where mutual trust functions well – ideal conditions for creativity to thrive. On top of that we have highly skilled and competent workforce. We have been able to hire experts who help drive the company forward,” says Miika Peltola.
Praise also goes to Business Finland, a state-owned company providing internationalization and innovation funding services, which is involved in enabling Polar Night Energy’s next investment. The pilot plant being built in the Tampere region will test the next version of the sand battery, which can convert stored thermal energy back into electricity. The overall efficiency of the new P2H2P system is expected to rise to as much as 90% when used in combined heat and power (CHP) production.
Polar Night Energy’s methods have also attracted widespread international interest: “We are conducting feasibility studies around the world. Inquiries come from every continent, including Antarctica. We are primarily focusing on Finland, the Nordic countries, and Europe, but the long-term goals are global,” adds Peltola.
Polar Night Energy
Polar Night Energy is a Finnish company developing high-temperature thermal energy storage systems for wind and solar power. Its patented Sand Battery technology enables a significant increase in renewable energy production while reducing reliance on fossil fuels.
Loviisan Lämpö
Loviisan Lämpö is a Finnish district heating company providing heat to customers in Loviisa, Pukkila, Pornainen, Siltakylä and the village center of Pyhtää, as well as Lappohja. Loviisan Lämpö is owned by CapMan Infra.
