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ISSN 2753-7757 (Online)

World’s first commercial ‘sand battery’


Polar Night Energy building, Finland Photo: Polar Night Energy 
The sand battery provides low emission district heating to the city of Kankaanpää in western Finland

Photo: Polar Night Energy 

What is claimed to be the world’s first commercial sand-based, high-temperature heat storage facility is now in operation at Polar Night Energy’s Vatajankoski power plant in west Finland, providing low emission district heating to the city of Kankaanpää.

Low-cost electricity heats up 100 tonnes of low-grade builders sand, held in a steel container measuring 4x7 metres, to around 500°C. This creates hot air that is circulated in the sand through a heat exchanger using Polar’s patented system. Sand is a very effective medium for storing heat, losing little over months at a time. The sand battery then discharges the hot air, warming water for the district heating system when needed, which is then pumped around homes, offices and the local swimming pool.


There has been much domestic interest in the green heat energy storage system as most of Finland’s gas demand was met by Russia. However, following the war in Ukraine and in the wake of Finland’s decision to join NATO, Russia has now halted gas and electricity supplies to the country.


The BBC recently visited Polar Night Energy to find out how the sand battery works. Click here to see the video on YouTube. 


pile of sand and spade

Sand is a very effective medium for storing heat, losing little over time

Photo: Polar Night Energy