- By Sebastian Anthony on August 6, 2013 at 7:51 am
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The network consists of 24 kilometers (15 miles) of road in the city of Gumi, South Korea. For now, the only vehicles that can use the network are two Online Electric Vehicles (OLEV) — public transport buses that run between the train station and In-dong.
Diagram of the SMFIR wireless power transmission technologyExact details of the system are hard to come by, but we believe that the power is delivered by cables that are around 12 inches (30cm) below the road surface. The power is transmitted wirelessly via Shaped Magnetic Field in Resonance (SMFIR), a technology developed by the Korea Advanced Institute of Science and Technology (KAIST) that essentially runs 100 kilowatts of power through some cables at a very specific frequency (20 kHz in this case), creating a 20 kHz electromagnetic field. The underside of the bus is equipped with a pick-up coil that’s tuned to pick up that frequency, and thus AC electricity is produced via magnetic resonance. (Read: How wireless charging works.) Transmission efficiency is an impressive 85% thanks to the “shaped” part of the technology, which targets the electromagnetic field at the vehicle, so that less energy is lost to the environment.
The OLEV receives 100 kilowatts of power via SMFIR, while maintaining a 17cm gap between the underside of the bus and the road surface. Because each OLEV has a small battery (about one-third the size of the battery in a conventional EV), only small portions of the road (5-15%) need to be electrified. Further increasing efficiency and reducing the radiation received by other road users and pedestrians, the electrified sections only turn on when an OLEV approaches. (In case you do get caught near a strip of electrified road as an OLEV passes by, the level of radiation produced by SMFIR is well within the limits imposed by international EMF standards.)
Moving forward, 10 more buses will be added to the network by 2015 — and presumably there are also plans to add more stretches of electrified roads. The fact that only 5-15% of the road needs to be dug up and replaced might sound positive at first blush, but it’s still a massive undertaking in any kind of built-up area. Trains and trams might require electricity for their entire runs, but it’s much easier to install overhead power lines than to dig up a road.
Still, if we push the logistical issues aside for a moment, it’s hard to overstate the advantages of a nationwide electrified road network. You would never need to stop at a filling/charging station ever again.
The design and engineering of cars would change dramatically, as large engines, fuel tanks, and batteries would no longer be required. Reducing our reliance on fossil fuels would of course be a boon to the environment, too. The electric road would be a network in the computer sense of the word, too, potentially allowing for all sorts of vehicle tracking, autonomous driving, vehicle-to-vehicle networks, smart braking, and more.
It’s just a shame that we’re probably decades away from a nationwide electrified road; the installation costs, in terms of construction work and lost productivity due to traffic delays, would really be quite phenomenal.
Now read: German student creates electromagnetic harvester that gathers free electricity from thin air
Research paper: Application of Shaped Magnetic Field in Resonance (SMFIR) Technology to Future Urban Transportation [PDF]