In an unsuspecting place just north of Helsinki, Finland, houses the world’s largest sand battery which keeps an entire town warm.
Polar Night Energy is the company behind the structure and, prior to its installation, Finnish energy company Loviisan Lämpö previously relied on conventional wood chip boilers to provide heat to the small town of Pornainen.
However, all of that changed in 2025, when the sand battery was constructed, which the firm describes as being ‘a large-scale, high-temperature thermal energy storage system that uses sand or similar materials as its storage medium’.
Now, the 1 MW thermal energy storage serves as the primary production plant of the local heating network and enables residents to experience reduced and stable energy costs.
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The sand battery stands at around 13 meters (43 feet) high and 15 (49 feet) meters wide, making it 10 times bigger than the previous sand battery engineered by the company in 2022.
An exclusive look inside the sand battery can be viewed below:
Could sand batteries be the solution to climate change?
So, does the technology have the potential to make a positive impact on the problem of climate change? Loviisan Lämpö CEO Mikko Paajanen seems to think so.
He said: “With the sand battery, we can significantly reduce energy produced by combustion and completely eliminate the use of oil.”
The sand battery is a more sustainable method of powering the town’s district heat network because it reduces combustion.
The battery itself is essentially just sand, a steel container and air circulation, meaning that no rare minerals - such as the type used in lithium batteries - are used.
In contrast, sand is widely available in supply and is not toxic.
The material also has a long lifespan, meaning that it should be able to operate for decades to come with very minimal performance loss.
According to Polar Night Energy, around a fifth of the world’s emissions originate from industrial heat production.
The company went on to explain: “Many industrial processes are heated with steam. Because steam is needed continuously and in large volumes, its production accounts for a significant share of industrial energy use and emissions.
“Today, much of this steam is produced by burning fossil fuels or solid materials such as wood or biomass. Fortunately, the drawbacks of combustion have become widely recognized, and the shift away from fossil fuels is accelerating.
“New technological solutions and their development play a central role in improving industrial energy efficiency and meeting climate targets. Electrification of industrial processes is one of the most sustainable routes forward. In Nordic countries, electricity is produced with almost zero carbon emissions for most of the time, making it a clean energy source for heat and steam production.
“Polar Night Energy’s Sand Battery is part of this electrification wave, as it uses electricity as its primary energy source.”