Swiss Start-Up Charges Electric Buses Through Their Tyres
Most electric buses charge overnight at the depot and then carry heavy batteries around all day. A young Swiss company wants to change that. Winduction, a spin-off from ETH Zurich, has built a system that charges buses wirelessly through their wheels while they wait at bus stops. ETH Zurich shared the story on 5 October.
The idea is simple. A plate about the size of a shopping trolley is set into the road at a stop. Coils inside the plate, connected to the power grid, create a magnetic field. A second set of coils inside a specially designed tyre picks up the energy and passes it to the bus battery. The name Winduction stands for 'wheel-based induction'.
Most wireless systems send power to the underside of a vehicle, but that gap is large and changes from model to model. The wheels are always touching the ground, so the distance is much shorter. The company says its system is more than 90 percent efficient from the ground to the vehicle.
There was one challenge. Normal bus tyres contain steel belts, which would turn much of the power into heat. So the team is working with partners on a completely new steel-free tyre.
Because buses can top up during short stops, they can use smaller, cheaper batteries. On the line between Zurich Airport and Oerlikon, plates would be needed at only 2 of 24 stops. Daytime charging can also make use of cheaper solar power, and it avoids every bus charging at once overnight, which lowers peaks on the grid.
Winduction is building a test lab and its own test bus stop in Winterthur, with support from the Federal Office of Transport and the Swiss Climate Foundation. The founders plan a first pilot in 2028 near Zurich Airport, where the bus will carry passengers for the first time.
