Electric cars could feed power back into grid through wireless 'antennas'

German researchers have unveiled a prototype wireless system that allows a car to receive and discharge power to the grid from coils under a road or parking space.

The car will perform to between 93-95% of its maximum capacity across a power range of 400 watts to 3.6 kilowatts, even if there is a 20cm gap between the coils

The car will perform to between 93-95% of its maximum capacity across a power range of 400 watts to 3.6 kilowatts, even if there is a 20cm gap between the coils

Researchers at the Fraunhofer Institute for Wind Energy and Energy System Technology IWES in Kassel believe their system will be 93% efficient even when there is a gap between coils in the road and the car.

Coils are built into the road which can wirelessly transfer electricity to a separate coil in the underbody of the car via a magnetic field. A charging system is also present in the car, with various connections for charging via modern charge spots and power outlets as well.

"Even with an air gap of 20cm, we achieve an efficiency of between 93 and 95%– and do so across the entire power range, from 400 watts to 3.6 kilowatts," explained Dr. René Marklein, project manager at Fraunhofer IWES. "Comparable systems achieve that kind of efficiency only over shorter distances, which limit their usefulness for cars with larger ground clearance."

The car is being presented at the IAA International Motor Show in Frankfurt in two weeks’ time.

Battery powered

The system also offers an option for wireless vehicle-to-grid storage. In situations where solar or wind sources are producing too much energy for a power grid, the batteries in the car can be used to store the excess energy. The cars then transfer this energy wirelessly back into the grid when renewable power dies down.

Fraunhofer scientists delve a bit further into their research in the short soundclip below.

Fuel of the future

Despite this being a prototype, the car may not have to wait long to get a full trial on British roads.

Last month, Transport Minister Andrew Jones confirmed that a series of world-first trials would be carried out to test how wireless charging technology could be deployed on the country’s motorways and A-roads.

These roads would supply similar wireless charging technology to the one that the researchers are presenting in Frankfurt.

Last week Nissan announced a partnership with Architects Foster + Partners to build the ‘fuel station of the future’, which would include systems to harness the potential of battery storage in cars. Ultimately, we could see the prototype cars pumping renewable energy stored from the grid, into electric fuel stations. 

Matt Mace


| renewables | solar | technology | transport | wind energy | Innovation


Energy efficiency & low-carbon
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