Are Car-Charging Roads the Future? Probably Not

Everybody agrees that the Achilles' heel of the electric car is the batteries and their limited range, currently around 100 miles on a good day. But suppose the EV could get its charge from the road, the way electric trains do? It’s not just a concept; there are test programs on both sides of the Atlantic.

In the latest charge-as-you-drive experiment, Highways England said this week that it had conducted a $300,000 feasibility study of powered roads and would proceed to an 18-month off-road trial. Wireless charging companies are being asked for proposals.

According to Highways England Chief Highways Engineer Mike Wilson, “The off-road trials of wireless power technology will help to create a more sustainable road network for England and open up new opportunities for businesses that transport goods across the country.”

It’s an interesting idea, and people have been circling around it for 100 years in science fiction, but the basic issue with any type of electrified roadways is cost. There are more than 4 million miles of roads in the U.S. If these roads cost $1 million a mile (about what light rail costs), my calculator says the cost would be $400 billion. Yes, we wasted more than that in Iraq and Afghanistan, but it would still be a difficult appropriation process when we can’t fund even basic road maintenance.

Wireless charging is a maturing technology, and a number of automakers — including Toyota on the next generation of Prius Plug-In Hybrid — will be offering it as an option in 2016 or 2017. “Within a decade, wireless charging could be the leading way of charging EVs,” says Navigant Research.

The basic idea is the EV owner drives over and syncs to a pad on the garage floor. This inductive process uses electromagnetic fields to transfer power inductively from that transmitter to a receiver on the bottom of the car. It’s not perfect; it's about 90 percent or so efficient.

In Milton Keynes, England, a program was launched to wirelessly recharge municipal buses, but in that case — as with garaged EVs — they have to be parked, the BBC reported. A 15-mile wireless network was put in place in Gumi, South Korea in 2013, with a pair of transit buses charging wirelessly.

A fascinating made-in-America approach is Solar Roadways, a family affair. Scott and Julie Brusaw live in Sagle, Idaho. They’ve designed, with the help of a $100,000 Federal Highway Administration (FHA) contract, a glass roadway surface that incorporates solar panels to generate as much as 3.34 megawatt-hours of electricity from four hours of sunlight a day. The first prototype simply proved the glass surface worked; then, with another $750,000 they got from the DOT, they built a small parking lot demonstration array.

Another $2.2 million was raised for Solar Roadways through an Indiegogo campaign. That’s almost $3 million invested in this mom-and-pop business. Clearly, people love this idea.

The Brusaws’ panels do have a bunch of cool features — LED lights that can send messages and warnings to drivers, heating elements to melt snow and ice, sensors and microprocessors. They don’t have electric vehicle charging, but that could be added — at more cost. To be fair, Scott Brusaw, an electrical engineer, claims the electricity generated means the panels would be self-supporting.

And I’m sure the Brusaws would dispute my $1 million per mile estimate, but there are some basic realities to confront here. In order for the LEDs to work, there’d have to be some kind of storage batteries because solar doesn’t work at night. And, of course, you’d need transmission lines to offload the electricity (so they could “pay for themselves”).

It’s also unclear how much electricity the parking lot display is generating. Of course, that power would go down when cars were parked over it, so it might not work for parking lots. Putting panels on overhead solar carports — something already working in my own town and at General Electric installations — is probably more practical.

Eric Weaver, the FHA official who led the testing of Solar Roadways, said, “It’s not very realistic to cover the entire highway system with these panels.” He added, though, “If you don’t reach for something, you’ll never get there.”

As electric cars get more efficient, and offer 300 miles or more on a charge, the urgency for powered roadways will probably decline. Because of high costs, these demonstration programs tend to offer proof the technology works, but then things stall at the funding stage.

Here's the snazzy video that showcases Solar Roadways:

And here's video refuting the idea as scientifically crazy: