Charging infrastructure is critical for e-mobility. But stopping to recharge isn’t always practical, particularly on long-distance journeys. One potential solution is currently being tested in numerous countries: electrified roads. Charging a vehicle as it drives may sound simple, but there are a number of challenges. These projects hope to solve them.
Wireless battery charging has become an increasingly common everyday sight, from phones to toothbrushes. But cars? Automaker Renault has teamed up with tech companies Qualcomm and Vedecom to see if they can bring wireless charging to the streets with an innovative road covering in conjunction with new car equipment. The principle behind it can be found in many kitchen cookers – induction. They believe the technique can recharge a vehicle travelling at up to 100 km/h, with the same capability as a current rapid charge point. Tests have already been carried out in the French town of Versailles on a stretch of road 100 metres long.
Their efforts showed that the technology only makes sense on heavily used city roads that are prone to traffic jams, as well as the busiest stretches of motorway. At around 8,000 euros for two metres of road covering, mid-term financial feasibility is questionable. “The problem is that roads have to be resurfaced every few years, which would include these expensive charging sections,” says Rachid Ait Bouhou from the German E-Mobility Association (Bundesverband eMobilität e.V. – BEM).
Sweden and Israel go wireless on the streets
In Israel, transport company Electreon is investigating how induction can be used to transfer energy to electric busses via copper coils. Tests have been ongoing since 2017, with vehicles fitted with just a small battery to carry them across stretches without charging. The company aims to implement its technology on an 11-mile stretch of road between the city of Eilat and Ramon airport.
Sweden is exploring a different option to charge electric vehicles on a two-kilometre test track, eRoadArlanda, near Stockholm. A movable arm connects to the bottom of the vehicle to transfer energy from a rail in the road. When the vehicle moves from the electric road to a normal surface, the arm is moved again and the current disconnected. The test is part of Sweden’s wider aim of achieving fossil fuel-independent transport by 2030.
Germany invests 50 million euros in test tracks
In Germany, wireless charging tests are currently focused on trucks. Since May 2019, hybrid vehicles fitted with pantographs – the electric pickups found on a tram – that connect with overhead cables, have been travelling up and down a five-kilometre stretch of the A5 motorway near Frankfurt. The trucks will gather data for another three years before a decision is made on whether to expand the solution. Similar experiments are also under construction in the north and south of the country – the result of a 50 million-euro investment by the Federal Ministry for the Environment.
Rachid Ait Bouhou from BEM, however, sees the solution as expensive and elaborate. “I’m not at all convinced by the tests with overhead lines. I can’t imagine there being sufficient capability or desire for a large-scale implementation on our roads and motorways.”
Compatibility presents a problem
Ait Bouhou also believes induction charging on the road is a long way off: “The biggest problem is bringing all the different stakeholders together. Traffic flow requires standardisation, which is extremely time-consuming. Every type of vehicle from every type of manufacturer would have to be fitted with the same system. The radiation and safety aspects would need to be agreed.”
Nevertheless, he does see areas that could be explored further. “Drivers of electric taxis could use induction charging at taxi stands as they wait for fares.” Car-sharing and delivery vehicles could also benefit. “Induction charging could be used everywhere where vehicles stand still for a longer period. We can expect to see stationary solutions in these areas in the next five years.”
A further solution: conductive concrete?
Munich-based company Magment has developed a slightly different answer to the problem, explains Rachid Ait Bouhou. “It’s an exciting option with conductive concrete that could be used instead of normal tarmac on road sections that need replacing.” The patented technology uses magnetisable concrete made of cement and magnetic particles from recycled waste electronics. The energy is transferred wirelessly, meaning it could be used to charge e-vehicle batteries while driving – without having to install and replace plates in the road. Magment is currently involved in various projects in Germany, Finland and China.