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Polar Night Energy - Sand Battery

This sand battery stores renewable energy in the form of heat for long time periods

A group of young Finish engineers have successfully installed the worlds first sand battery, designed to store energy from green sources. Together they created 'Polar Night Energy', the company which made the battery.

The battery system can store renewable energy for months. Researchers believe it could solve the country's year-round crisis in power supply in Finland, a leap forward in providing cheap, green energy to the population. Furthermore the solution directly combats a significant problem with solar and wind energy: storage.

Alternative batteries tend to have significant environmental impacts and issues regarding waste disposal. Convenrtional batteries often require rare earth minerals produced in conflict environments. In comparison, Polar Night Energy's solution uses waste sand from industry, upcycling old materials and furthering their lifespan. The sand is piled up inside a large silo, pictured in the thumbnail of the linked video below:

The sand battery can store energy in the form of heat at temperatures up to 500 degrees Celsius! This provides warmth to homes in winter months and rainy days.

The battery works by heating the sand and then circulating the heat generated using a heat exchanger. The battery discharges the hot air to warm the water for the district heating system, which is pumped around homes, offices, and the local swimming pool.

This diagram from the BBC explains the process:


Want to see more? Polar Night Energy have some great videos to check out on their website.

Other benefits

Source (Polar Night Energy, 2022)


Polar Night Energy. “Technology.” Polar Night Energy, 2022,

McGrath, Matt. “Climate Change: 'Sand Battery' Could Solve Green Energy's Big Problem.” BBC News, BBC, 5 July 2022,

Power in Numbers

Uses waste material. Low social impact.


Energy storage solution.



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