Finland’s radical answer to renewable energy’s biggest headache: The world’s largest sand battery
A small town in southern Finland has deployed a significant technological solution to address the intermittency of renewable energy. The town of Pornainen is now home to the world’s largest commercial sand battery, a facility designed to store clean energy as heat to support local district heating requirements.
The battery is a 13-meter tall and 15-meter wide structure filled with 2,000 metric tons of crushed soapstone. This system captures electricity from the grid during periods of low cost and high wind or solar generation, converting it into thermal energy. This heat remains trapped within the insulated silo for extended durations, allowing the town to draw upon stored energy for heating water long after the initial production occurred.
Developed by Polar Night Energy and commissioned by Loviisan Lämpö, the facility produces enough energy to cover the heating demands of the town’s 5,000 residents for nearly a month during the summer and roughly one week in the winter. Data suggests this transition has reduced greenhouse gas emissions from the local heating network by approximately 70% and decreased the reliance on wood chips by 60%.
The system presents a distinct advantage over chemical alternatives like lithium-ion batteries by avoiding the use of rare earth materials. While the technology faces limitations regarding the conversion of heat back into electricity, its efficiency for long-term thermal storage makes it a viable candidate for heating networks currently dependent on oil or coal. Representatives from Polar Night Energy note that interest in this thermal storage method has arrived from global markets looking to decouple heating production from fossil fuel combustion.
As the energy transition proceeds, municipal leaders and researchers view this facility as a model for regional energy management. By disconnecting the timing of electricity procurement from the actual delivery of heating, the town of Pornainen maintains a stable supply despite the variable output of wind and solar power.