Subway systems around the world use a “third rail” system to power their electric carriages. Two of the rails support the vehicles, while the other one carries the electrical current. An appendage attached to the side of the subway cars rides along the third rail and conducts electricity to the motor. Sweden has converted a short portion of highway near Stockholm to a similar system that recharges electric vehicles while they drive.
The 2-kilometer-long highway runs between the Arlanda airport and a logistical support facility nearby. A movable arm connects to a track embedded below the pavement surface to recharge the battery while a vehicle is in motion. The track is divided into 50-meter-long sections. Power is only applied to each section when needed. The system is able to identify the owner of each vehicle and bill electronically for the amount of electricity consumed. If the vehicle departs from the electrified travel lane for any reason, the arm disengages automatically. No power is supplied if the the vehicle is not moving.
Hans Säll, CEO for eRoadArlanda, the consortium that designed and built the electric highway, tells The Guardian that existing vehicles and roadways can be adapted to take advantage of the technology. He said both current vehicles and roadways could be adapted to take advantage of the technology, and noted that Sweden only has 20,000 kilometers of highways. “The distance between two highways is never more than 45 kilometers and electric cars can already travel that distance without needing to be recharged. Some believe it would be enough to electrify 5,000 kilometers.”
One of the factors that makes the electrified highway idea appealing is that it costs far less to install than conventional systems that use overhead wires.
At about €1 million per kilometer, it is also cheaper to build than a traditional tram line. The concept is completely safe for pedestrians and animals. “There is no electricity on the surface.” Säll says. “There are two tracks, just like an outlet in the wall. Five or six centimeters down is where the electricity is. But if you flood the road with salt water then we have found that the electricity level at the surface is just one volt. You could walk on it barefoot.”
One of the factors encouraging Sweden to consider such novel technology is the desire to reduce carbon emissions. Battery electric cars are much cleaner than cars with internal combustion engines, but cost more than comparable conventional cars because they need large batteries to reduce range anxiety. If vehicles are able to recharge while driving, they could be fitted with smaller, less expensive batteries. That in turn would lower the cost of electric vehicles and make them more appealing to a wider cross section of drivers. No cost estimates for the mobile charging hardware have been announced.