Original URL: http://www.theregister.co.uk/2012/07/08/ev_roadway_charge_demo/

Japanese boffins demo EV on-the-move charging

Except it’s low-powered and inefficient

By Richard Chirgwin

Posted in Science, 8th July 2012 23:01 GMT

Electric vehicles have two problems: to make them “zero emission”, they need to be recharged from “clean” sources; and range remains a challenge. A Japanese proposal would, if it worked, address the second – but probably exacerbate the first.

A team from the Toyohashi University of Technology has demonstrated an electric field coupling system that they say would let cars be recharged on-the-go through their tyres.

This isn’t easy: the electricity has to be coupled across several inches, which amplifies the losses that take place in trying to get electricity transferred across a wireless channel. The Toyohashi demonstration showed that it was feasible to transfer between 50 and 60 watts through a four-inch concrete block, coupling to the tyres’ steel belts and powering a light bulb.

Efficiency is, however, treated optimistically by researchers in this field. Last year, similar research was hailed as a success since only 20 percent of the total energy was lost in the circuit.

Of course, if the vehicle isn't charged from a clean source, then 20 percent loss means you don't only move the emissions to wherever the power station is; each vehicle's emissions are that much worse than if you recharged with a cable.

Toyohashi University of Tech says the power transfer in its EVER (Electric Vehicle on Electrified Roadway) would have to be scaled up 100 times – transferring more like 5 kW than 50 W – to be useful. ®