Several countries, including Sweden, Denmark and Germany, are testing whether electric road system (ERS) can be used to electrify road networks.
An ERS charges moving vehicles with induction loops located in or next to the road, or with catenary wires suspended above the road.
All of these methods mean that vehicles do not need to be parked in order to charge and there is consequently less need for large vehicle batteries.
Proponents of the ERS idea claim that it will overcome “range anxiety” – the worry felt by electric vehicle drivers about the distance their vehicle can travel before the battery needs to be charged.
Now researchers from Chalmers have used data from over 400 passenger cars to study real driving patterns on different parts of Swedish national and European roads.
They have used the data to calculate, among other things, the battery size needed to complete all journeys given possible charging options – stationary versus ERS – charging patterns, and total costs including infrastructure and batteries.
The results show that a combination of home charging and ERS on 25% of the busiest national and European roads would be the optimal solution.
This proportion of ERS would allow batteries, which account for a large part of the cost for an electric car, to become significantly smaller – maybe only one-third of their current size.
"We see that it is possible to reduce the required range of batteries by more than two thirds if you combine charging in this way,” said lead researcher Sten Karlsson. “This would reduce the need for raw materials for batteries and an electric car could also become cheaper for the consumer."
Another possible benefit is that peaks in electricity consumption could be reduced if car drivers did not entirely rely on home charging but also supplemented it with electric road charging. “Many people charge their cars after work and during the night, which puts a lot of strain on the power grid. By instead charging more evenly throughout the day, peak load would be significantly reduced,” explained Karlsson.
There are already a few short test sections fitted with different electric road technologies in Sweden, including in Lund and on Gotland, but the first pilot with a permanent electric road is now underway. The Swedish Transport Administration is building a 21-kilometre stretch between Örebro and Hallsberg alongside the E20 motorway. The new electric road is expected to be completed in 2026.
The study, “Benefits of an Electric Road System for Battery Electric Vehicles” is published in the World Electric Vehicle Journal and is written by Chalmers researchers Wasim Shoman, Sten Karlsson and Sonia Yeh.