Stoelzle has collaborated with Finnish company Polar Night Energy to store and regain green electricity from a sand-based storage solution.

The glass manufacturer gains green energy via waste heat from furnaces and green electricity from photovoltaic panels, and needed a solution to store its excess energy.

Therefore, in autumn 2022, Stoelzle participated in an innovation pitch, which was organised by the Austrian Chamber of Commerce.

At the pitch, Stoelzle decided to collaborate with Polar Night Energy; a small start-up company from Finland, founded by Markku Ylönen (left) and Tommi Eronen (right).

The Finnish company has developed a patented sand-based thermal energy storage.

It is the world's first commercial solution to store electricity in the sand as heat to be used in a district heating network.

Mr Ylönen said: “As a material, sand is durable and inexpensive and can store a lot of heat in a small volume at a temperature of about 500–600°C.”

The first storage of this kind has successfully been installed in the town of Kankaanpää, Finland.

Heat storages can help to increase intermittent renewables in the electrical grid, and waste heat can be used to heat homes, which is a step towards combustion-free heat production.

Niklas Zwettler (see left), Head of R&D at Stoelzle Glass Group, continues to lead this project and further steps are being explored to extend the process.

He said: “Glass production is a very energy intensive process. We have set ourselves the target to halve our CO2 emissions by 2030, and become carbon-neutral by 2050. So far, Polar Night Energy has discovered a way of extracting heat to warm water and feed local heating systems.

“Now, we need to discover how to retrieve electricity from the energy that is stored in the sand, in order to have a reliable source of green electricity to fire our furnaces. We’re excited to see how this system will work for us.”