As different European countries test the idea of an electric road system (ERS) to charge EVs as they move, researchers at Sweden’s Chalmers University of Technology published a new study combining, for the first time, such a proposal with real-life driving patterns of local drivers.
In the paper published in the World Electric Vehicle Journal, the scientists explain that ERS charges moving cars with either loops in or next to the road, or with wires suspended above vehicles, similar to trams and trains. All variants mean that cars do not need to be parked to charge and that there is less need for large batteries storing energy to deal with the issue of “range anxiety.”
Using data from over 400 passenger cars to assess real driving patterns on different parts of Swedish national and European roads, the Chalmers group calculated, among other things, the battery size needs 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 electric roads on 25% of the busiest national and European roads and home charging would be optimal. The batteries, which account for a large part of the cost of an electric car, can become significantly smaller, reaching, at best, one-third of the 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. This would reduce the need for raw materials for batteries, and an electric car could also become cheaper for the consumer,” Sten Karlsson, co-author of the study, said in a media statement.
According to Karlsson, another benefit of implementing such a system is that peaks in electricity consumption would be reduced if car drivers did not entirely rely on home charging but also supplemented it with electric road charging.
“After all, 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,” he said.
But different groups of motorists also have different conditions for benefiting from the combination of stationary charging and ERS.
“There are big differences between groups, depending on driving patterns and proximity to electric roads. Even in the optimal case, some would manage with only electric road charging, while others would not be able to use the opportunity at all,” Wasim Shoman, lead author of the paper, said. “For example, we see that those who live in the countryside would need almost 20% greater range on their batteries compared to those who live in a city centre.”
The study also shows that small batteries do not automatically lead to charging through ERS, as consumers will not necessarily decide to plug in at every given opportunity.
“The business model, therefore, becomes extremely important because benefits and costs may become unevenly distributed. And there are no decisions yet on what the business model should look like,” Karlsson said.
The researcher noted that it is important to answer these questions sooner rather than later as there are already a few short test sections with different electric road technologies in Sweden, including in Lund and on Gotland, while the Swedish Transport Administration is building a 21-kilometre electric road between Örebro and Hallsberg alongside the E20 and it is expected to be completed in 2026.