If an electric car charges while driving, the size of the battery can be reduced by up to 70% and the load on the power grid can be spread out over the day.
This is according to a study by Chalmers University of Technology in Sweden, where researchers have combined an electric road system (ERS) with real-life driving patterns of Swedish drivers.
Batteries add cost and weight, and making them smaller would make electric vehicles (EVs) cheaper and better to drive.
The idea of ERS emerged 20 years ago and the latest study found charging on the move can suit most people, if not everyone.
The Swedish government has proposed a ban on new petrol and diesel cars from 2030 to reduce CO2 emissions, with similar trends across Europe as part of a shift to EVs. The EU will require all new cars sold to have zero CO2 emissions from 2035.
As this development progresses, challenges are also increasing, including the uneven load on the power grid and where to charge EVs, said a Chalmers spokesperson.
Several countries, including Sweden, Denmark and Germany, are testing whether ERS can be used to electrify road networks. An ERS charges moving vehicles with either loops in or next to the road, or with wires suspended above vehicles, similar to trams and trains.
ERS means vehicles do not need to be parked to charge and there is less need for large batteries storing energy to overcome range anxiety, a term referring to the fear an EV driver experiences about the distance their vehicle can travel before the battery needs to be charged.
Chalmers researchers have used data from more than 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, battery size needs to complete journeys given possible charging options (stationary vs ERS), charging patterns and costs including infrastructure and batteries.
The results show 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 for an electric car, can become significantly smaller, at best only one-third of the current size.
“We see 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,” said researcher Sten Karlsson.
It is expensive technology, but a UK study estimated an 'E-highways' system could pay for itself within 15 years while drastically cutting carbon emissions
Other positive effects are peaks in electricity consumption would be reduced if drivers did not rely on home charging only and 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 charging more evenly throughout the day, peak load would be significantly reduced,” said Karlsson.
“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. For example, those who live in the countryside would need almost 20% greater range on their batteries compared to those who live in a city,” said co-researcher Wasim Shoman.
The first pilot with a permanent 21km electric road is under way in Sweden, with the road expected to be completed in 2026. Electric roads have also been introduced in South Korea to provide a wireless power source for electric buses.
It is expensive technology, but a UK study estimated an “E-highways” system could pay for itself within 15 years while drastically cutting carbon emissions.
The Swedish ERS study found electric roads could be about 50% cheaper to introduce than a national network of charging stations and larger batteries for EVs.
While the ERS is mainly being considered for trucks to allow them to travel longer distances with smaller batteries and to avoid waiting for charging, private cars can also benefit.
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