An underground flow of liquid nitrogen will next year begin coursing beneath the German city of Essen, in the Ruhr region – as part of a €13.5m project.

The flow’s sole purpose is to cool the world’s longest superconducting cable, which is due to be installed as part of a trial to replace the city’s high-voltage transmission system with a cheaper, safer, and smaller alternative.

Superconductors are regarded as forward-thinking solutions for saving space, because the method of delivering an electrical current is installed underground, and are also seen as particularly efficient modes of electricity transmission in urban areas.

Detailed planning of the project will commence in the next few months – which includes the determination of the exact route.