A recharger for vehicles that is built right into the road is the subject of a patent by German technology company Ingenieurgesellschaft Auto und Verkehr (IAV). Their technology would allow electric vehicles to be charged as they drive over any road embedded with a recessed wireless recharging strip, using electromagnetic induction.
This idea has been floated before: DARPA funded the PATH program, a prototype in Berkeley, CA; it moves buses along set tracks. Researchers at the Korean Advanced Institute Of Science Technology have been able to achieve 80% efficiency with a 1 cm gap between the power strip and the vehicle charger.
But until this year, little work has been done on using the concept to charge electric cars going at freeway speeds along regular roads, while enabling the electric vehicles to also move freely onto and off of the charging strip, as IAV has done.
IAV has achieved 90% efficient transmission for electric vehicle charging from roads using recessed electrical conductors that generate a magnetic field; activated only when the sensor detects that an electric car is over the induction field. Radio chips would identify individual electric vehicles for correct billing.
The key issue has been maintaining a set distance between the sensor under the vehicle and the roadway.To solve that, the vehicle sensor must use active suspension and to also utilize optical electronic controls to maintain a consistent distance between the road and the sensor.
(Electromagnetic induction in-road charger for electric vehicles video)
This technology reminded me of the tele-motor-coasters used for personal transportation in the world of Hugo Gernsback's 1911 novel Ralph 124c 41+.
...Ralph bade Alice sit down on a chair in the vestibule. He pressed a nearby button twice and a servant brought two pairs of what appeared to be roller-skates.
In reality they were Tele-motor-coasters. They were made of alomagnesium and each weighed only about one and a half pounds. Each had three small, rubber-covered wheels, one in front and two in the rear. Between the wheels was a small electric motor - about the size of a lemon...
"...the Tele-motor-coasters would not be possible were it not for the metallic streets. The flat spring which trails on the street between the two rear wheels must make continuous contact with the metallic "ground" else the current cannot flow.