A new electric bus prototype doesn’t just pick up passengers at its bus stops; it also picks up a charge for its battery.
Unlike its public transportation contemporaries, the electric “Aggie bus” at Utah State University has no overhead wires. Nor does it need to be plugged into a power source. Instead, the battery receives a five-kilowatt wireless boost from a charge plate installed at each bus stop. With consistent routes and frequent stops, the bus is able to charge as it goes rather than requiring a big battery on board to stockpile an entire day’s worth of power.
The induction set-up requires that a transformer be split between the bus and the charge plate. When the driver pulls over at a stop, the two halves of the transformers align, and five kilowatts of energy are zapped from the plate to the bus. Nikola Tesla first demonstrated this wireless energy transfer—dubbed the “Tesla effect”—in 1891, but the research team at Utah State has overcome some of the barriers that had been keeping wireless charging technologies from widespread use in public transportation. Induction-based buses have already been in use in the Netherlands since 2010 and in Italy for almost a decade, but this will be the first these buses see of North America.
One of the biggest hurdles researchers cleared was to boost the bus’s the efficiency to 90 percent. They also built in some wiggle room so the bus will charge even if it’s a few inches beyond the ideal 10-inch gap between bus and charge plate. The prototype is already running its rounds on the streets with 25 kilowatts of power, and a commercial model with a 50kW charge is set to launch in mid-2013.
Image courtesy of USU (Utah State University)