CHICAGO — Consider it the ultimate in frictionless “fueling”: Wireless charging allows a driver of an electric vehicle (EV) to pull up over a pad and automatically begin recharging their battery, without having to exit the vehicle and connect to a charging station.
The technology is already in play, but on a much smaller scale. Wireless smartphone charging transmitters are now being offered preinstalled in vehicle consoles, and it is increasingly common to find tables embedded with wireless charging stations at airports and businesses. Wireless EV charging works on the same basic principle: An induction coil inside a transmitter on the ground generates an electromagnetic field that is picked up by an induction coil inside a receiver installed on the bottom of an EV. This energy is transferred directly to the EV battery.
But while wireless charging for smartphones is becoming familiar, it is currently very much a perk for EVs, bought on the aftermarket by enthusiasts and techies.
“It’s a luxury option: Rather than have to deal with the messy task of physically plugging in your car, you could drive into your garage or onto your driveway and charging would start automatically,” said Graham Evans, associate director of supply chain and technology for London-based IHS Markit’s automotive division. Wireless charging systems also come at a premium, with the average cost for an in-home system about $2,500 for the transmitter and receiver, compared to only $300 to $500 for a plug-in solution.
Despite its current niche as a status symbol, wireless charging has tremendous long-term potential in transforming the entire transportation energy infrastructure—specifically in dynamic applications. These would allow an EV to recharge while in motion as it moves over a series of charging transmitters embedded in the road. Dynamic wireless charging is in test in several countries, including Sweden, Norway, the United Kingdom and China. In the United States, tests of wireless charging systems for electrified buses and trolleys are taking place or being considered in California, Denver and Utah, while the Illinois Tollway is weighing a test on a stretch of highway near Chicago.
And should wireless charging intersect with autonomous vehicles, the transformative potential is even greater. But before it gets to this stage, the technology needs to move beyond the pilot phase, and the roadblocks are not easy to overcome.
Whether the vehicle is sitting in place or moving down the road, providing a charge to an EV battery without the benefit of a cord remains a work in progress.
“Both technologies are still in this R&D phase,” said Scott Shepard, a London-based senior research analyst covering energy for Navigant, Chicago. He said the charging industry is developing communication and basic wireless standards, which would enable original equipment manufacturers (OEMs) and automakers to offer wireless charging receivers in vehicles as a feature. Today, EV owners must have their vehicle retrofitted to accommodate a wireless receiver.
Once the standards are in place, “It would take wireless charging in both formats from something that takes a vehicle hack right now to something that’s more of a vehicle option, and the industry would pass into a commercialization phase from there,” he said.
Static wireless charging would be the first to go commercial, but it could be anywhere from two to as many as five years before most OEMs begin offering it as an option on a new EV. That said, many large automakers are currently working with wireless charging system developers to test the technology. One of these developers, Watertown, Mass.-based WiTricity, has partnered with General Motors, Honda, Nissan and Hyundai. Volkswagen Group’s Audi brand is developing wireless charging as an option for some of its e-tron plug-in hybrids. And in 2018, BMW began taking orders for a wireless charging system for its plug-in hybrid 530e iPerformance model in Germany, with plans to introduce it to other countries, including the United States.
The widespread deployment of dynamic wireless charging—despite the tests taking place around the world—is a much bigger project.
“The idea of large sections of roads in towns and cities being fitted with stretches of … wireless charging technology to enable everyone to charge—it’s quite an idealistic notion in a utopian future that this would happen,” Evans said. “The costs of it will be huge, the infrastructure implications would be huge, and for that reason I would say a low level of adoption—never mind massive adoption of the technology—is a long way out, if ever.”
Cost is perhaps the biggest hurdle, especially because governments would likely shoulder the initial upfront burden. As the continual effort to raise funding for infrastructure on the federal and state level shows, paying for conventional roads—let alone electrified roads—is politically difficult.
The private sector could also make an investment in static wireless charging stations, but the business case is murky for that as well.
“The revenue model in public EV charging remains very, very poor—very few people are making money out of charging EVs at the moment,” Evans said. “This will change in time with increased throughput through stations, but the revenue model is still very, very challenging.” Also, the largest public charging station networks, including Volkswagen’s Electrify America, have already made enormous investments in plug-in infrastructure, which they would be loath to tear up.
One advantage wireless charging has over plug-in is that it is EV brand-agnostic, says Shepard of Navigant. A charging receiver can communicate with any transmitter, unlike with plug-in systems, which are still dealing with a mix of connector standards.
“Theoretically, it is a solution that can work across a number of vehicles, and in that capacity, the cost of the system could be shared across an entire fleet, vs. various corded charging systems, which—for reasons of connection standards or ownership patterns—are only going to be accessed by certain user types, and therefore costs will be shared by that specific set,” he said. “Wireless is an expensive technology, but there are some advantages in applicability to all vehicles.”
Meanwhile, wireless has technical considerations, especially with dynamic charging systems.
“They’ve proven that power can be transmitted and received; the proof of concept works,” Evans said. The levels of efficiency for stationary systems range from 88% to 95%, which is similar if not superior to a plug-in station, he says.
“But achieving that level of efficiency in a dynamic environment is very difficult,” he said. “The alignment is very important between the transmitter and receiver.” While position sensors can help an EV align with a stationary charging system, “having someone drive in a very specific manner down the street to ensure a good level of charging is more difficult,” he said.
The expansion of wireless EV charging also depends, of course, on the increased use of EVs. Plug-in EVs make up only about 1% of new light-duty passenger vehicle sales in the United States, although total EV sales jumped 81% in 2018, according to EV information website Inside EVs. One issue that has dampened consumer enthusiasm for EVs is their price premium compared to conventional vehicles, and most of that increased cost is because of the battery.
But dynamic wireless EV charging would lessen the need for costly large EV batteries, and it could help erase that price disparity. This is especially true for mass-transit vehicles, such as buses. John Eichberger, executive director of the Fuels Institute, Alexandria, Va., points to a pilot test in Sweden, where electrified buses are charging up wirelessly over inductive charging pads located at the bus stops.
“Every couple of stops, they are getting a full minute of charge,” he said. “In doing that, they can reduce the size of the battery several-fold. Instead of a 100-kilowatt battery, they could do a 10-kilowatt battery because they are recharging every couple hundreds of yards.”
Longer term, the expansion of wireless EV charging will depend on its intersection with another potentially transformative technology: autonomous vehicles.
“The future for wireless charging is somewhat dependent on the progression of self-driving technology,” Shepard said. “There are definitively other use cases for it—home charging is potentially attractive, and fleet use cases—but for the technology to become transformative, we do need to see some adoption of an automated driving system.”
And autonomous vehicles’ expansion depends on vehicle ownership models shifting toward car sharing and mobility as a service, in which consumers no longer own a car but instead pay to be transported, either as a one-off purchase or through a subscription with an autonomous vehicle fleet. For this, “the need for automated charging through wireless becomes greater,” Shepard said.
In this utopian future, the current gas station model would be defunct. But in the next couple of decades, once wireless charging hits its commercial stride, it could become a premium feature for enterprising c-stores, Eichberger said. This is especially true of those positioned in urban markets or on highways that can offer a top-up charge to EV drivers.
“People won’t deplete their EV battery all the way; they’re going to drive 50-60 miles and plug it in,” he said. “If you have a charger and your competitor doesn’t, [the EV driver] may come into your store to get that 10-minute top-off. And if you have an inductive pad, they can pull in and start getting a charge while they’re in the store.
“It’s a higher level of frictionless convenience,” he said, “which could provide a great opportunity in a competitive space.”