Charging electric vehicles while they are on the move may seem a bit out-there. But, in fact, we already do it for major groups of vehicles—trams and trains, for instance. French cities have completely wireless trams, and their record is good. After 10 years and about 7.5 million miles, they haven't reported serious problems.
In Sweden, Volvo is applying the same technology to roads, opening up the possibility that people would no longer have to fear getting stranded by a dead battery—a major hurdle to people's willingness to buy an electric car. Led by Mats Alaküla, researchers are looking at two types of "conductive charging," both where vehicles would stay in continuous contact with the power supply. One method charges via lines overhead; the other, like the French trams, uses two metal bars in the road.
Alaküla says the important part of the second system is "the pick-up": The connector between the vehicle and the ground. It needs to compensate for drivers who move about the lane (unlike trams that stay in a fixed position). He describes the set-up as an "industrial robot sitting upside down—it adjusts to movements, one meter each way, and retracts completely if drivers move outside the lane.
"If you imagine two lanes, the power system would be in the right lane," he says. "The pick-up keeps in contact with the supply, until you keep moving sideways. Then, the truck will go to the battery. When you go back, it automatically identifies the track, and reconnects."
The road is safe for pedestrians, he says. The system only electrifies sections of the track when vehicles pass at a certain speed. To electrocute yourself, you'd need to step out in front of a fast-moving vehicle, which is a bad idea anyway.
Behind the research is the assumption that batteries will never give the required range—especially not for long-haul trucks. As Alaküla says, batteries are "necessary, but not enough." They could provide enough power for driving in cities or getting from one major road to another. But highway driving requires something more.
Volvo is testing the two conductive methods at a 400-meter track near Gothenburg. Its trucks have gone up to 50 mph so far. Alaküla expects the work to continue another year before his team takes the concept to a full road. Eventually, he thinks the concept could be used for anything bigger than a motor-bike: cars, buses, and different types of trucks.
Separately, Volvo's rival Scania is testing technology based on inductive charging—where the charge is transferred via an electromagnetic field and does not require physical contact. Alaküla thinks the conductive solution could be cheaper. But he's open to the possibilities: Volvo isn't committed to either option at the moment, beyond its research effort.
"There are a handful of technologies. Volvo is not going to sell electric roads. We are contributing to society to make traffic independent of oil supply. If it turns out there is a better technology than the one we are working with, then we'll support that instead."