Energy Storage
World’ s largest sand battery achieves its targets
The Sand Battery built by Polar Night Energy for Loviisan Lämpö has now been in operation for one year. With the help of the Sand Battery, climate emissions from the Pornainen district heating network have been reduced by 70 percent. The technology also has significant potential to reduce emissions in industrial applications.
Text & images by Polar Night Energy
The world’ s largest Sand Battery was commissioned in Pornainen, Finland, in June 2025. During its first year of operation, the Sand Battery has met all performance targets and design specifications set for it. It serves as the primary production facility for the local district heating network.“ We have demonstrated that the Sand Battery works as designed and can deliver significant emissions reductions in a cost-effective way. This is an excellent practical example of the energy transition, where energy production based on combustion is replaced with renewable energy,” says Liisa Naskali, Chief Operating Officer of Polar Night Energy. The Sand Battery is an innovative high-temperature thermal energy storage system that stores renewable energy as heat in sand or similar materials. It can store energy for periods ranging from days to weeks, helping support the growth of renewable energy.
“ The first year went even better than we expected. Commissioning was exceptionally smooth, and reliability has been excellent: there have been zero interruptions in district heating delivery. Our cooperation with Polar Night Energy has been very successful,” says Mikko Paajanen, CEO of Loviisan Lämpö. The investment decision for the Sand Battery was accelerated by the previous energy crisis. At the same time, Loviisan Lämpö’ s biomass heating plant was approaching the end of its useful life as the primary production facility.“ We wanted to reduce our dependence on a single fuel source. Recent developments have shown that volatility in energy prices is no longer an exception but the new normal. The Sand Battery provides protection against exactly these kinds of situations,” says Sauli Antila, Operating Partner at CapMan Infra. The Sand Battery has a substantial storage capacity and can store energy for long periods of time. This enables the utilization of the cheapest hours in the electricity market. In addition, the system participates in Fingrid’ s reserve markets.“ One of the most interesting performance indicators has been how much cheaper electricity we have been able to procure compared to average market prices. On average, we have been able to
24 Heat Exchanger World October 2026 www. heat-exchanger-world. com