In Focus: Inductive Charging 0


Inductive charging, or wireless charging, is not a new concept. Dating back to the late 1800s, Nikola Tesla first experimented with inductive charging to power lighting devices, but it has only recently become a commonplace technology. While you used to have to plug your phone charger into your cell phone and an electrical socket (as well as an adapter when abroad), now all you need to do is place your phone on top of an inductive charger. Instead of transferring energy through a cord, inductive charging wirelessly transfers energy by means of a device’s close proximity to a short-range electromagnetic field created within a charging station.

The greater the distance there is between the receiver within the cell phone and the electromagnetic transmitter coil of the charger, the more inefficient the charging process becomes. However, in 2007, MIT physicist Marin Soljacic and a team of researchers experimented with another of Tesla’s ideas, using resonance to transfer energy more efficiently at greater distances. Basically, resonance utilizes more than one coil resonating at the same frequency within a close proximity to transmit streams of energy to receivers at greater lengths. In Soljacic’s experiment, resonating coils powered a light bulb from a distance of about seven feet.

Inductive charging and implications for electric vehicles

A major application of research developments such as MIT’s have paved the way for the advent of inductive charging roads for vehicles powered by electrically charged batteries. A technological advancement that was merely a theory until recently, in-road charging infrastructure for electric vehicles equipped with built-in receivers has become a reality in the town of Gumi in South Korea. The Korea Advanced Institute of Science and Technology (KAIST) has built over seven miles of roads with buried electrical cables in downtown Gumi. Select public transit buses that travel this route have been equipped with what is called “Shaped Magnetic Field In Resonance.” Energy is transmitted from power cables under the road’s surface that create a magnetic field, which then interacts with the coil on the vehicle, and this interaction channels an electrical current to the vehicle’s battery. This energy transfer could be up to 90% efficient or greater!

How do electric vehicles compare?

Electric vehicles – even charged with electricity from the dirtiest fuel mix at power plants – produce comparable levels of greenhouse gas (GHG) emissions, perhaps with slightly more emissions than an extremely fuel-efficient gasoline-powered vehicle. Otherwise, according to the Union of Concerned Scientists, electric vehicles are generally more efficient and can produce as little as three times less GHG emissions as gasoline-powered vehicles, depending on the location’s electricity mix. All-electric vehicles (as opposed to hybrids) also produce no local air pollution, which can be a great benefit to cities’ urban air quality.

Overall, electric vehicles would produce far fewer GHG emissions, especially as renewable energy increasingly contributes to the electricity mix across the country. Given the benefits, what are the stumbling blocks to widespread adoption for electric vehicles?

Consumers exhibit two major concerns with electric vehicles:

  • Insufficient charging infrastructure
  • Range anxiety

Why is in-road inductive charging important?

In-road inductive charging would, particularly regarding travel within cities, remove many inhibitions about range anxiety and charging infrastructure. Many cities have struggled to spur greater electric vehicle adoption, because city policymakers are unsure whether to first provide more charging stations throughout the city to combat short battery range or to provide incentives for consumers to buy electric vehicles in order to increase demand for charging infrastructure. This problem has often been described as a typical chicken-or-egg dilemma, meaning policymakers struggle to identify in which aspect to invest public funding in order to create a catalyst for the other aspect to ultimately achieve a public good.

Placed strategically and spread across a large enough scale within a city, in-road chargers could be a game-changer for electric vehicle adoption. Demonstrating the effectiveness with public transit buses could instill confidence in the infrastructure and science, as South Korea’s experiment appears to do.

The future

An electric vehicle must be manufactured with an electrical receiver in the body of the car to generate electricity to charge the vehicle, which is not currently the case with electric vehicles in the U.S. However, manufacturers would most likely respond to market demand by producing electric vehicles with receivers if sufficient in-road charging were available to the public.

High costs remain a concern for implanting several miles of electrical cables underneath roads, but many governments are implementing partial in-road charging at bus stops and in parking garages. These are similar to charging station hook-ups, except charging is wireless over an inductive spot. Governments in Italy and the Netherlands have installed wireless chargers at some bus stops to help top up battery life or provide partial charges during breaks. Since no one is quite sure how in-road charging will perform or hold up over time, governments will undoubtedly look to South Korea’s example to potentially emulate the success of in-road charging while learning to buffer against any unintended consequences.

Editor’s Note: If you are interested in repairing and maintaining hybrid/electric vehicles, check out CleanEdison’s Hybrid Vehicle Training. If you are more interested in installing and maintaining EV charging stations, check out CleanEdison’s EV Charging Installation Training

Original Article on CleanEdison Blog

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