A sand battery in Finland is transforming sustainable heating

From housing to businesses and a municipal swimming pool, this battery is slowly changing the game for Finland's district heating.
By Teodosia Dobriyanova  on 
A split-screen shows a photograph of the sand battery from the outside (left) and an illustration stripping down the same building's walls to show how it works on the inside (right)
Watch Next

By 2050, more than 68 percent of humanity is expected to live in urban areas. But are our cities prepared for all the challenges this entails? This Mashable series explores how our cities can become more sustainable and equitable homes to their human and non-human inhabitants.


Heating Finland's cities is becoming more sustainable thanks to sand. Finnish startup Polar Night Energy has developed a battery that uses sand to trap and store energy from solar and wind electricity. The battery is a high-energy storage facility located in Kankaanpää and is fed power from the grid whenever excess electricity is available. Warming up to 600℃, the system traps the heat until it's needed, when it can be released as either hot water, steam, or air.

Sand is the second most exploited natural resource after water and its emissions-heavy mining is highly damaging to local ecosystems. Polar Night Energy has stated that it uses high-density sand, which is only sourced from abundant areas and cannot be used in construction.

So far, the sand battery is providing a local district heating network, heating homes and businesses, as well as a municipal swimming pool. Scaling up, a similar sand battery will be installed in the city of Pornaien in a recent agreement between Polar Night Energy and district heating company Loviisan Lämpö.

Picture of Teodosia
Teodosia Dobriyanova
Video Producer

Teodosia is a video producer at Mashable UK, focussing on stories about climate resilience, urban development, and social good.


More from How to Change a City
How can we adapt cities to extreme heat?
A black and white illustration explains the heat island effect. In the middle, there's a dense city emitting heat where temperatures are at 35 degrees Celsius (95 F), while the surrounding countryside is much cooler, at 25 degrees Celsius (77 F)

How can India prepare its cities for severe heatwaves?
A still image showing a main road in New Delhi in the heat. Caption reads: "heat relief"

Latest Videos





Tate Modern's Electric Dreams celebrates digital art before the internet
A collage shows a group of people in an immersive 'Electric Dreams' room (left) and a composite of Palestinian-American artist Samia Halaby as she draws (right)

Watch Nicola Coughlan and Ncuti Gatwa in 'Doctor Who' Christmas special trailer
A man and the woman sit on the floor, staring up.

"A complicated Christmas puzzle": Richard Curtis on adapting his stories for film
'That Christmas' writer RIchard Curtis

Paul Mescal takes method acting way too far in 'SNL' promo
A man in a hoodie sits at a table, looking serious.


The biggest stories of the day delivered to your inbox.
This newsletter may contain advertising, deals, or affiliate links. Subscribing to a newsletter indicates your consent to our Terms of Use and Privacy Policy. You may unsubscribe from the newsletters at any time.
Thanks for signing up. See you at your inbox!