The city of Pornainen, in southern Finland, now has the largest battery of sand ever built, capable of reducing carbon emissions from the local heating system by up to 70%.
Developed by the company Polar Night Energy, the facility replaces an old wood chip power plant and has been in operation since June.
How the battery should work
- The reservoir measures about 13 meters high by 15 meters wide and stores up to 100 MWh of thermal energy, enough to keep the city warm for a week.
- Its principle is simple: the excess of renewable electricity, such as solar and wind, heats the sand to temperatures of up to 600 ºC inside an isolated silo.
- This heat can be maintained for months and then released to generate steam or heat water used in the district heating system.
Unlike conventional batteries, the sand one does not provide electricity directly, but acts as a thermal energy storage (TES), with an efficiency of 90% in the charge and discharge cycle.
The company is already studying ways to convert part of this heat back into electricity through steam turbines.
Important progress for decarbonization
With dimensions ten times larger than the first sand battery in history, also created by Polar Night Energy, the Pornainen structure is seen as a strategic step towards carbon neutrality and can serve as a model for other cities in cold regions and with large intermittent production of renewable energy.
fontes: Olhar Digital
