Suppose you could recharge your car on the go …

Suppose you could recharge your car on the go … The limited range and the price of the electric vehicle are an obstacle to its widespread adoption, as are the limited availability and low power of charging stations. The dynamic recharging concept could facilitate mass adoption of electric vehicles by shifting part of the energy vector to road infrastructure.

The New Charging Technologies working group coordinated by Leonard, VINCI’s forward-looking innovation platform, pools the expertise of Eurovia, VINCI Autoroutes and VINCI Energies. It is currently exploring dynamic charging solutions in conjunction with key players in the sector (industrial undertakings and research centres).

Recharging by induction: the potential

Tomorrow’s roads will be able to supply power to electric vehicles. There are three existing technologies that make this possible. Catenary charging, one of the latest innovations tested, offers high power transfer efficiency and draws on the experience gained by manufacturers in the railway sector. ‘It needs a lot of maintenance, causes visual pollution, and most importantly there’s no interoperability from one type of vehicle to another, so we have rejected this solution. It’s better suited to HGVs,’ explains Didier Deschanel, Director for Innovation at Eurovia.

Conductive rail charging, on the other hand, uses various configurations of mechanical arms that make contact with a cable running along a trench or a conductive strip on the road surface. Some challenges remain when it comes to cleaning and frost protection at the bottom of the trenches and the risk of damage to the articulated arms from sudden changes in direction or objects in the road. ‘To keep the rail operational, this solution calls for a lot of maintenance work. It gets very tricky in snowy or frosty conditions,’ comments Pierre DelaigueVINCI’s Director for Connected, Autonomous and Electric Mobility Projects.

Although further research is still needed before coils can be introduced in pavement structures on an industrial scale, it is induction-based solutions that seem to have the greatest potential, with their low maintenance costs, absence of visual pollution, and the interoperability that they allow from one vehicle to another. ‘This involves installing loops in the road and circulating a current through them to create an electromagnetic field that is picked up by a receiver loop fitted underneath the vehicle. This is how the pavement transmits electrical energy to the vehicle,’ says Didier Deschanel.

So far, this technology has worked well in the laboratory and on test tracks (at the Satory complex near Versailles) over relatively short distances. ‘Now that we have won a call for projects, we’ll be able to carry out tests on longer stretches of road with vehicles travelling at 130 km/hour,’ remarks Pierre Delaigue. In the longer term, the idea would be to equip motorways with this technology.


How far do you have to drive to recharge your car?

This depends on the available charge power. ‘One possible approach would be to neither recharge nor discharge your vehicle as you drive. The infrastructure would supply just enough energy to the electric motor for the driver’s motorway mobility needs. Users would leave the motorway at the end of their journey with the same battery level as the car had when it joined the motorway, enabling them to carry on to their final destination. So the idea is to meet mobility needs at a given time without having to draw on the car’s on-board energy,’ affirms Didier Deschanel.

Where does the electricity network come in?

We estimate that the energy requirement for continuous coverage of a motorway lane is 2 MW/km. As this power requirement is distributed all along the network, the electricity supply and distribution infrastructure would in principle be less bulky than is the case with high-power charging stations located at a particular site,’ adds Arnaud Banner, Technical Director at Omexom.

What about the economic model?

Zoals op elke Franse snelweg betaalt de gebruiker voor de afgelegde afstand door middel van tolheffing. De kosten van de gebruikte stroom kunnen hierbij worden doorberekend in het te betalen bedrag. Automobilisten met een elektrische auto betalen zo per verbruikt kilowattuur of per gereden kilometer. “Uiteindelijk is ons doel om elektrische auto’s gemeengoed te maken door de kosten van de accu aan boord te verlagen”, bevestigt Didier Deschanel.