Sustainable Energy

The Case for Building Electric Roads

The falling price of lithium-ion batteries may mean that electrified streets don’t make sense for private cars—but could be useful for public transit.

Qualcomm's wireless charging could keep a car going. And going. And going.

The prospect of hitting the open road and never having to refuel is a compelling one. And as several new field trials have demonstrated, it’s also increasingly realistic. 

The technology, known as inductive charging, is straightforward in theory. A system sets up an alternating electromagnetic field, and then an induction coil in a smaller device harvests power from it. It’s easy enough to make work for small objects that don’t move—some smartphones now offer it as a feature—but transferring enough power to larger, moving objects has proved tricky.

Now the chipmaker Qualcomm has announced that it’s successfully built a 100-meter test track near Paris, France, to test its own version of the technology. So far, it’s shown that it’s possible to charge vehicles at 20 kilowatts as they drive along the track at highway speeds, and it works when two cars are traveling in opposite directions along the same strip, too.

Meanwhile, an Israeli firm called ElectRoad recently announced that it has been testing a similar system on an 80-foot test track. As Scientific American recently reported, it now plans to build out a system along a section of bus route in Tel Aviv, with the longer-term vision of installing a system on the entire 11-mile shuttle link between the city of Eilat and Ramon International Airport.

The benefits are fairly clear. If a vehicle can be charged as it goes, it doesn’t need to pull up at the side of the road be plugged into an electrical supply; it can, in theory, run indefinitely. It also means that vehicles can make do with far smaller batteries (they still need them for acceleration), saving a lot of weight and expense. And placing inductive charging hardware on the road is safer, prettier, and more versatile than using live overhead lines to power electric vehicles.

There are disadvantages. First, it requires tearing up sections of road to lay, which is disruptive and expensive. Second, the systems themselves aren’t exactly cheap, requiring a continuous line of electromagnets for the length of the road. As result, the infrastructure would be unlikely to extend beyond a few high-traffic routes through a city.

That makes it unclear whether electrified roads would ever make sense for charging passenger cars—especially based on the current model of ownership where independently minded humans choose to drive when and wherever they please. Also, given that the price of batteries continues to plummet and electric cars advance in efficiency, range anxiety looks set to become increasingly less of an issue for most drivers.

But it may still work for the kinds of bus routes that ElectRoad envisions, where less weight means more efficiency and routes are standardized. And it may even make sense for the robotic taxi fleets that we keep hearing about, if they broadly stick to well-defined routes and only deviate from charging strips for a mile or two at a time.

(Read more: Qualcomm,  Scientific American, “How Other Battery Manufacturers Could Help Tesla Reach Its Own Goals,” “Why Range Anxiety for Electric Cars Is Overblown,” “The Paris Motor Show Confirms It: The Future Is Electric")

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