Last year in my search for sustainable transport technologies, I wrote about two different ways to make an electric highway. One is with overhead cables, the other with wireless charging lanes. Here’s a third: onboard recharging through a slot in the road surface. Like the overhead cables idea, it’s being trialled in Sweden, and the pilot project opened last week.
This form of electric road has been developed by a company called eRoad Arlanda. They install a groove down the centre of a highway lane. Electric vehicles driving along the lane automatically lower a charging arm that drops into the slot and recharges the battery. The charging slot activates automatically too, in 50m stretches, and switches off when there is no EV to charge.
If the technology works, it could be installed across the Swedish road network. That would be enough to provide charging on the go for a nationwide switchover to electric vehicles, part of the country’s long term plan to phase out fossil fuels.
It’s obvious why this system is an improvement on a network of charging points. No need to stop and plug in – just go, and charge on the road. It’s also clear why it’s better than overhead cables, which only trucks can use. But is it better than wireless charging, which Britain is testing at the moment? Let’s look at the advantages and disadvantages.
First, eRoad Arlanda’s system is quick to install. They can lay a kilometre of track in an hour on existing roads. It wouldn’t be massively disruptive to upgrade highways. It’s also relatively cheap, and by their own calculations the whole 20,000 kilometre upgrade would pay for itself in just three years from savings on fuel – quite an extraordinary claim. It also works for all types of vehicles. Wireless charging is more effective with a smaller air gap, so it’s less efficient for vehicles with a higher ground clearance.
Among the disadvantages, there’s more to go wrong with a physical connection. No matter how well engineered that charging arm is, it’s going to be more mechanically complicated than a wireless charging connection. Wireless charging is usually considered to be less efficient and slower, but it’s come on in leaps and bounds in the last couple of years. The conductive charging of eRoad Arlanda may only be marginally more efficient than the latest generation of wireless technologies. Some EV companies already allow wireless charging, whereas cars would need to be retrofitted to use the charging arm, or manufacturers would need to start adopting it. As we’ve seen with swappable batteries, it’s not easy to get car companies to commit to a standardised system.
I’m not enough of an expert to say whether this system is better than the various wireless alternatives in development. One thing I do know though: with charging points, on-board solar, improvements in battery technology and electric roads, no one will be worrying about where to charge their EV in future. In fact, keeping your car powered up could be a far more convenient and seamless experience than petrol cars are today.