Park and charge: These pads transmit power wirelessly from the floor of a garage to the bottom of a car.
It’s also possible to boost the signal with coils called repeaters. In the demonstration Giler gave, coils installed under carpet squares allow power to leapfrog from a wall outlet to anywhere in the room.
Witricity is one of a handful of companies working to extend the range of electric chargers. The company has developed a prototype table that charges devices placed anywhere on its surface—even if they remain inside a backpack or purse—and a wireless keyboard and mouse that can be powered from a computer monitor, eliminating the need for batteries. (Apple has patented a similar idea.) The company has also developed a charger for electric cars. It’s a half-meter-wide pad that sits on the floor of a garage—just drive over it, and the car starts to charge.
Witricity is partnering with several companies to bring the technology to market. It has a multimillion-dollar contract with Toyota to develop charging for battery-powered vehicles (soon it might not make sense to call them plug-in electric vehicles), and has also announced a partnership with Taiwanese electronics manufacturer Mediatek to develop products for charging portable electronics.
Katie Hall, Witricity’s chief technology officer, says the company is working on components that will add the necessary electronics to a portable device. It’s also working to make charging sleeves for mobile phones that are no larger than the covers people typically use to protect their phones. The company isn’t certain how much these will cost, but Hall says the system for charging cars wouldn’t cost much more to make than the chargers that electric-vehicle owners often install in their garages anyway.
Several other companies are developing inductive chargers that can send power efficiently through the air. Siemens and BMW are developing chargers for electric cars, and Qualcomm recently bought a startup that had developed its own wireless electric-car chargers. A company called Fulton Technologies has technology that sends wireless power through a few centimeters of marble, as well as from the floor of a garage to an electric vehicle.
A handful of researchers are even working to extend the concept to allow charging of electric vehicles while they are out on the road. Researchers at Oak Ridge and Stanford recently developed detailed concepts for such a system. In a $2.7 million federally funded project, researchers at Utah State University are installing a system to charge buses as they stop along a route in Salt Lake City.
In the Oak Ridge model, 200 coils would be embedded in a section of the roadway and controlled by a single roadside device; successive coils would be energized as electric vehicles pass over them, providing enough power for the vehicle to reach the next series of coils a mile down the road.
John Miller, a research scientist at Oak Ridge, estimates that each series of coils plus the controller would cost less than a million dollars. “Wireless chargers for electric vehicles are so convenient. You don’t have to mess with plug cables. You don’t care what the weather is. You don’t even have to think about it. I think it’s going to catch on superfast,” Miller says.