Electric Buses Recharge as They Drive

Two South Korean buses can now effectively drive for ever thanks to wireless charging points built in to the road surface. The system is similar to that used for some trams, but works in a way that means other vehicles can use the same road.

The buses themselves work in the same way as an electric car, but the lithium-ion battery is around the third the size as those used in rechargable vehicles. Unlike the cars, the buses don’t need to stop for recharging at any point.

The system involves embedding power strips running along the road surface at regular intervals. The strips appear to be about 18 inches wide. For the charging to work, the combined length of the individual strips has to be around five to fifteen percent of the total road length of the route, minimizing the amount of installation and disruption needed to make a particular route compatible.

The bus doesn’t actually touch the power strips. Instead the strips use a magnetic field to pass on the power to a receiving unit on the base of the bus, which is 17 cm above the ground.

According to the Korea Advanced Institute of Science and Technology (KAIST) the power strips are able to detect when one of the buses is about to pass over and will only activate the power transmission for this moment. As well as saving on electricity, this means ordinary vehicles can drive along the roads without any safety concerns. KAIST says the electromagnetic fields don’t pose any risk to human health.

The technology had previously been tested on trams (without overhead cables) in an amusement park and on buses at KAIST’s facilities, neither of which were on “roads” used by other vehicles.

At first two buses will operate in the city of Gumi, both running the same 15 mile round-trip route. The plan is to add another 10 buses by 2015.

(Image credit: KAIST)