Power Up On The Go

A major concern for people thinking about buying their first electric vehicle is something that has come to be known as range anxiety, the fear that the car will run out of juice before they get to their destination or a recharging point. The perception is so widely felt that it’s considered an obstacle to large numbers of consumers adopting the technology. Yet experts say electric vehicles powered by renewable sources like the sun and wind are necessary to achieve energy independence and to slow human contributions to climate change.

One way of extending electric vehicle range besides the difficult road of improving battery technology is to build recharging infrastructure like that which has been developed for gasoline distribution and sales. But the act of recharging itself also throws up obstacles for widespread adoption–getting a quick boost to extend range by 50 miles can take 20 minutes using DC fast charging, and connecting to a regular AC household plug can take 20 hours to refill a depleted battery.

A few groups of researchers around the world are looking beyond these early issues in the developing electric vehicle industry. Instead of building refuel points like those used in the gas station model, they are working on delivering electricity to vehicles while they’re on the go, no stopping needed. It’s called wireless power transfer, and it is starting to show promise. Learn more and see the video below.

At its heart, the technology uses inductive coupling to wirelessly send electricity from a transmitter built into the roadway to a receiver mounted under the vehicle.



One project in South Korea is using wireless power transfer to operate a tram line and buses. A pilot project in Geneva is using the technology to run high-frequency bus routes around the city.

Now at the Department of Energy’s Oak Ridge National Lab, researchers say they have made advances on their own in-motion wireless charging system. The work sets the stage to bring on-the-go battery recharging out of the lab and out onto real roads.

In the lab phase of their work, they equipped a small low-speed electric vehicle with pickup coils on its chassis. They installed six power-carrying transmitter coils in a simulated road and drove the vehicle over it. They were able to show the efficiency of the power transfer both on the vehicle side as well as the grid-connected transmission side. While the receiving coal rolled over a transmitting coil, power flowed quickly into the vehicle’s battery, and the coils energized and de-energized in less than a millisecond.

They then installed carbon ultracapacitors into the vehicle and the grid mockup to smooth the power spikes that pulsed when the transmitting and receiving coils were working. Ultracapacitors are capable of quickly absorbing rushes of electrons, then sending them to the battery in a steady stream.

While there is still more work to do before this work can be commercialized, the positive results point to a possible wholesale change in how transportation operates. The ultimate idea is for roadway coils along highways to be connected to grid electricity or to be fed directly by solar panels or other forms of alternative energy.

“The initial results and the industry firsts achieved demonstrate that wireless power transfer is well on its way to becoming a viable option for America’s energy and transportation future,” the lab says in a video. “In-motion charging, which allows drivers to charge their vehicles while they are driving, is recognized by the U.S. Department of Energy as an enabling technology for mass-scale electrified transportation.”



All gifs created from Youtube video courtesy of Oak Ridge National Lab.