Wireless Electric Car Charging Is Coming—And It Could Help Stabilize the Power Grid

Easy wireless power transfer could reduce anxiety on the part of consumers and utilities alike. 

BMW

As electric vehicles spread across the land—analysts expect them to comprise 50 percent of new car sales by 2040—the next great challenge will be upgrading the charging infrastructure to support them. It’s a complex process, demanding a system that’s ubiquitous and fast at the charging station so drivers won’t have to panic about where their next hit of electricity will come from, but also won’t strain the electric grid altogether. And of course, it also has to be easy—because if we’ve learned one thing during the rise of EVs, even the slightest hassle can be a deterrent to potential owners.

In terms of ubiquity and speed, Tesla has the best jump on this looming crisis with the Supercharger network it’s building out (though the chargers are proprietary to Tesla vehicles). More and more, you’re seeing universal stations popping up at malls, parking garages, sports arenas, office buildings, on streets in bustling downtowns—in addition to the garages and driveways of particularly bought-in owners. They’re mostly corded stations mounted on walls or posts. Not exactly hard...but when you have to do it a daily basis, or even hourly if you manage to stitch together stations while running errands, it very much becomes a thing.

There are solutions in the pipeline for the forgetful or the easily-annoyed; Tesla revealed a robotic charging snake a few years ago that could slither over to your car and plug itself in, and Volkswagen has partnered with automotive assembly line robotics manufacturer Kuka on an articulating charging station that will do the same. But the ultimate solution could involve none of that at all. Wireless charging—the long-simmering solution for charging electronic devices without having to remember to actually plug it in—could solve a variety of problems relating to the complexity and ease of charging networks....while bringing a few benefits of its own, as well.

Variations of the technology are already deployed for charging smart phones and other small electronics, but they generally require exceptionally close proximity for the juice to jump between copper coils that can transmit energy via oscillating magnetic fields. That’s the more familiar variant, called electromagnetic inductive charging. Boston-based WiTricity, however, is leading the charge for another variant known as "magnetic resonance." The company, —spun off from an MIT effort in 2007—has created technology that uses power transmitters and receivers finely-tuned to the same frequency, allowing greater efficiency in the transfer and also increasing the distances the power can travel, up to two meters for practical applications.

Though those applications can vary from military to industrial to consumer tech, the company has elected to focus almost entirely on the automotive market. “Vehicle charging is a good match for the transmission distances and power levels we’re able to achieve,” Grant Reig, the company’s senior product manager, told The Drive. “You can have a pad at your home or at the mall or lines of them at taxi stands, and without having to do anything or establish any contact, electricity will start flowing automatically.”

The system, he explains by way of analogy, is like that of an musical note establishing a resonant frequency with objects nearby, causing them to vibrate in tune—picture an opera singer shattering a wine glass with a specific note. “The efficiency of that resonance goes up dramatically at that note,” Reig said. “With a magnetic resonance, we tune the magnetic field to the right frequency between the loop of wires in the transmitter and receiver, and that efficiency also goes up.”

The result is a system that generates far less power loss than other methods of wireless charging—with  end results of 90 to 93 percent efficiency—and is thus able to generate charging speeds that match or exceed those of wired chargers. The system is also safe, with built-in obstacle detection systems to turn itself off if pets or people inadvertently find their way into the power path—though in general, Reig says, only magnetic objects would be impacted. 

“I’ve stuck my hand between the power sources, and it’s fine,” he said.

Reig says the rollout for this technology will follow a familiar chicken-and-egg pace, where the charging pads will grow with the number of vehicles that are equipped with the technology, WiTricity doesn’t manufacture the technology itself, but rather licenses the innovation to auto manufacturers and suppliers. The first vehicle out of the gate is the 2018 BMW 530e sold in Europe. Nissan, Hyundai, Honda, and Toyota are also developing the technology; Reig estimates that there will be two manufacturers offering it in the United States by 2019, three to five by 2020, and a dozen by 2021.

There are pluses beyond convenience for drivers, too. One of the supplemental benefits to this system is the fact that it can easily generate two-way power transfer, enabling the vehicles to send power back into the grid. The company says that this capability will help maintain a balance between renewable energy availability and the peak demands generated on a daily basis. 

“Distributed energy sources could reduce or eliminate the need to bring expensive peak demand power generators online," Reig said. "In return for this benefit to the utility, customers may be incentivized in the form of a premium payment on the electricity provided during these peak need times or possibly be provided free energy in times of low demand.”

So in short, parked EVs transmitting wirelessly onto WiTricity-developed pads can help stabilize power demands, becoming backup power sources as electric cars grow in popularity. Honda R&D Americas and WiTricity are, in fact, presenting a paper on this subject this week at the Society of Automotive Engineers World Congress in Detroit.

There’s yet another possible benefit: Systems like this will also come in handy once autonomous cars enter the picture. One of the benefits of autonomy is, of course, the fact that the cars can move themselves when needed. So a parked car won’t have to linger at a charge port until its owner retrieves it, as happens now. The car can just drive off, freeing the spot for the next robo-car that comes along.