Bus companies around the world are slowly transitioning to electric fleets, backed up by manufacturers like Hyundai, Daimler, BYD and Proterra. Though the latter managed to eke out 1,100 miles on a single charge of the batteries in its 40 ft Catalyst E2 max last year, regular day-to-day driving will be significantly less. Keeping these e-buses topped up en route can involve installing networks of overhead hoods or cables that the buses can access tram-style, but others are taking a wireless route. Momentum Dynamics has announced the first 200 kilowatt wireless charger in North America, which sees a BYD electric bus in Wenatchee, Washington, receive a cable-free top-up during routine transfer stops.

Buses aren't trundling through city streets constantly, sometimes they stop for a while – to change drivers, wait for the appropriate set-off moment or to bring a bus in line with a route timetable at certain points. Momentum says that when the BYD K9S makes a scheduled stop at the Link Transit in Wenatchee for just 5 minutes, its batteries will wirelessly receive more than enough charge for it to roll on its next route.

Momentum hasn't revealed whether the addition of its wireless charging system has altered the basic layout or specs of the modified K9S transit bus. But it does say that the e-bus just needs to be brought to a stop over the system's transmitter embedded in the road for charging to start automatically.

"The simplicity along with seamless charging allows Link Transit to operate all of our urban service routes continuously without the need for midday charging," said Link's Todd Daniel. "Link is planning to expand this technology for our longer rural routes in the near future, which will assist in the agency's goal of 100 percent fleet electrification."

Momentum reckons that the potential cost savings to bus operators running an electric fleet could add up to millions of dollars every year, compared to fleets of diesel and hybrid vehicles. The company is planning to install more wireless chargers across the US later this year, before heading to Europe in 2019.