Courtesy Utah State University

Imagine: instead of stopping for gas, a bus that could recharge while at a red light.

For a lot of cities, the future of public transportation is going to be the good old bus. That doesn't mean the bus itself will be good and old.

Mannheim, Germany, and Gumi, South Korea, recently joined a growing list of cities outfitting electric buses with "induction charging" — a wireless technology that charges their batteries on the go. The advance remains in its trial phase in the United States, but will get a major public debut early next year in Long Beach, California. The city's transit authority has contracted to install the system on 10 buses on a route that runs downtown.

"I think we're on the verge of seeing much larger adoption," says Michael Masquelier, chief executive at WAVE, which develops the charging system. "We have somewhere between 10 and 20 additional opportunities in cities in the U.S. that we're working on to deploy. There's a tremendous amount of interest."

The wireless system works when one charging pad is attached to the bottom of an electric bus and another is planted in the road at a key point along the transit route. After the bus stops over the pad in the road, the induction charge sends power to the battery via a wireless transfer that can travel across several inches of airspace. A few minutes later — depending on the size of the battery — the bus is ready to resume its route.

The system offers multiple advantages to traditional electric bus charging. Chief among them is that a wireless bus doesn't have to be taken off the road to get a full charge from a depot. It can last the full transit cycle of 16 hours by stopping over the charging pad a couple times during the day, says Masquelier, whereas a traditional electric bus must be replaced halfway through its cycle by another bus with a full battery.

That advance gives transit agencies great flexibility. Some will be able to reduce the size of the bus fleet. Others can extend the duty time of a bus by charging it throughout the day. Still others may build buses with smaller batteries, which is great for both performance and maintenance. All these options should save a transit agency money while increasing efficiency.

"The incremental cost of adding these in-route chargers is significantly less than the capital expenditure to add additional buses to a route," says Masquelier.

The U.S. wireless system was developed and tested at Utah State University. (WAVE is a Utah State spin-off company.) A small prototype called the Aggie Bus has been roaming the campus since late last year, and a regular 40-foot bus will take over full-time duties this fall. The University of Utah campus will be getting a wireless bus, too, coordinated to serve the light rail line that comes from Salt Lake City.

Many fixed routes will only need one or two charging pads to maintain power throughout the day, says Masquelier. That's an enormous upgrade in both cost and appearance from the overhead catenary wires that charge some electric transit vehicles. (The system works for trolleys, too, and will soon debut on one in Monterey, California.) The main drawback is that once a charging pad has been planted in the road it becomes difficult and expensive to change the route.

Masquelier sees three big barriers keeping this next-generation bus from getting widespread use. The first is establishing partnerships with local power companies to put the infrastructure in place. The second is standardization of the technology. The third is finding a model city; that could be Long Beach, he believes, if the city ends up expanding the 10-bus trial program to its entire fleet.

"When a very innovative, very high-profile transit agency in California jumps from 10 buses to converting their entire fleet, I think all the other transit agencies in the U.S. will look at it and say we can do this, too," he says.

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