Sand Battery Thermal Energy Storage in Finland

The Sand Battery technology, developed by Polar Night Energy, represents a groundbreaking approach to thermal energy storage (TES) by using locally sourced sand. The system, which will have a heating power of 2MW and a thermal storage capacity of 250MWh, is designed to support district heating networks while also participating in grid balancing markets. This innovative method involves heating sand using electricity and retaining that heat for later use in industrial processes or heating applications.

With the completion of this project, expected in summer 2027, Lahti Energia aims to reduce its fossil-based emissions by approximately 60% annually. This is achieved by cutting natural gas use by 80% and decreasing reliance on wood chips. The Sand Battery's large capacity enables it to not only fulfill heating demands but also contribute to balancing supply and demand in a grid increasingly reliant on variable renewable energy sources.

The project is notable for its scale and the unique choice of sand as a storage medium, which is both cost-effective and environmentally friendly. The structure will be 14m high and 15m wide, showcasing the potential of sand as a viable alternative to traditional materials used in thermal energy storage systems. Furthermore, the use of sand aligns with sustainability goals, as it is abundant and does not involve complex processing.

Polar Night Energy, acting as the main contractor, is set to begin construction in early 2026, following the successful deployment of a smaller scale 1MW/100MWh Sand Battery system earlier in the year. This advancement in TES technology not only supports local energy needs but also positions Finland as a leader in innovative energy solutions, paving the way for future developments in the thermal storage sector.