Finland Pioneers World's Largest Industrial Sand Battery for Renewable Energy Storage

Finland is taking a groundbreaking step in addressing one of the biggest challenges of the energy transition: the intermittency of renewable energy. The country has commissioned the world's largest industrial-scale sand battery, developed by Polar Night Energy and operated by Loviisan Lämpö, in the town of Pornainen. This system can store surplus electricity from variable sources like wind and solar power as heat, providing for the heating needs of homes and industries even during winter months.

The sand battery technology fundamentally operates by superheating sand or similar granular material inside a steel tank to temperatures between 500 and 600 degrees Celsius using excess electrical energy. The heat can be stored in this material for months and is then released as hot air or water into the district heating network when needed. Polar Night Energy first deployed a commercial sand battery in July 2022 in cooperation with the Vatajankoski power plant in Kankaanpää. This pilot project had a heating power of 100 kW and a storage capacity of 8 MWh.

The new industrial-scale battery in Pornainen boasts a significantly larger capacity, delivering 1 MW of thermal power and offering a storage capacity of 100 MWh, approximately ten times that of the Kankaanpää unit. This massive system stands about 13 meters high and 15 meters wide, filled with approximately 2,000 tons of crushed soapstone, a by-product from local fireplace manufacturer Tulikivi. The stored heat can cover almost a month's heat demand in Pornainen during summer and nearly a week during winter.

The economic and environmental impacts of this technological advancement are substantial. According to Mikko Paajanen, CEO of Loviisan Lämpö, the sand battery is expected to reduce annual CO2-equivalent emissions from Pornainen's district heating network by around 160 tons, achieving a nearly 70% cut in climate emissions. Previously, a significant portion of the heating demand was met by burning oil, which has now been completely phased out thanks to this system, with wood chip consumption also considerably reduced. Furthermore, the battery's optimized operation, based on electricity prices and Finland's grid operator Fingrid's reserve markets, supports grid stability and helps lower energy costs.

Finland's move aligns with the country's broader energy policies and goals. Finland aims to be carbon neutral by 2035 and targets increasing the share of renewable energy in its total energy consumption to 50% by 2030. Russia's cessation of gas and electricity supplies to Finland after the war in Ukraine further accelerated the country's need to transition to renewable energy. Long-duration thermal storage solutions like sand batteries play a critical role in ensuring energy security against such geopolitical risks.

Analysts and market expectations suggest that sand battery technology will gain significant traction in the global energy storage market. The global sand battery market, valued at approximately $1.2 billion in 2024, is projected to grow at a compound annual growth rate (CAGR) of 15% to 23%, reaching an estimated $4.86 billion by 2034. This growth is driven by increasing demand, particularly in areas like industrial process heat storage and district heating systems, coupled with governmental support. These projects in Finland highlight the potential of sand batteries as a cost-effective and sustainable solution for renewable energy integration and the decarbonization of the heating sector.