There’s a lot of excitement around autonomous vehicles, and electric autonomous vehicles in particular. Many people envision a day when driverless EVs will chauffeur us around safely and emissions-free -- while allowing passengers to work, read or take a nap instead of watching the road.

The less visible, but essential player in this autonomous electric transportation future is wireless charging.

For vehicles to be truly driverless, they need to be able to refuel on their own too. Wireless charging -- though still in its early days of consumer adoption -- is one reason why EVs are considered the preferred platform for autonomous cars. Wireless charging liberates vehicles from gas pumps and plugs, and allows for virtually limitless electric range if chargers are strategically placed.

This week, wireless charging took another meaningful step toward broad adoption.

Wireless power transfer company WiTricity announced a new partnership today with Nissan, building on existing partnerships with General Motors and Toyota. The news is significant, because it signals that EV stakeholders have successfully avoided the type of standards battle that burdened the EV fast-charging sector -- creating additional hurdles for the nascent EV market to overcome.

In the case of fast chargers, European and American automakers insisted on using one charging standard, while Nissan and other Asian manufacturers insisted on using another. As a result, two different types of fast chargers are being built and paid for across the U.S.

WiTricity’s latest announcement shows that automakers have recognized how critical interoperability is for simplifying the EV charging experience and prompting broader adoption of EVs.

"WiTricity is partnering with Nissan to catalyze wireless charging in the EV market and move the industry forward to an interoperable future," said WiTricity CEO Alex Gruzen. "In order for us to realize a future of transportation that is electrified, shared and autonomous, we need a wireless charging solution that works for all vehicles.”

Why working with automakers matters

WiTricity saw a big win last month, when SAE International selected a circular coil design -- the type of design WiTricity uses -- as the standard all automakers must use for wirelessly powered EVs. These systems will now be tested to inform a global set of wireless charging guidelines, with buy-in from all automakers.

Because of the standards hurdle, the first vehicle-integrated wireless charging system isn’t expected to come to market until 2018, with the Mercedes-Benz S550e plug-in hybrid (PHEV) luxury sedan. However, Gruzen believes there could be a product announcement this year.

EV owners don’t have to wait for in-vehicle technology. Aftermarket solutions for wireless charging already exist. Tesla owners, for instance, can buy an aftermarket system from Plugless Power for $4,120. But because automakers haven’t signed off on these products, they may not support them.

WiTricity doesn’t offer aftermarket products. Rather, the company licenses its technology to Tier 1 suppliers like Delphi, IHI and TDK who build products for carmakers. At the same time, WiTricity works directly with OEMs like Nissan, Toyota and GM to develop its technology further. It comes as no surprise, then, that Gruzen isn’t a big fan of aftermarket solutions.

“I think that this is a critical system. So you need to make sure that it's integrated well from the mechanicals, to thermals, and proper shielding so that none of the car systems can be impacted,” he said, as well as “that the software and the physical connector interfaces are blessed and approved.”

There aren't going to be autonomous Ubers without wireless charging

WiTricity was founded in 2007 to commercialize technology patented two years earlier by a team of physicists from the Massachusetts Institute of Technology, led by Professor Marin Soljačić. The company’s claim to fame is its magnetic resonance technology that provides highly efficient power transfer from the grid to a vehicle, regardless of vehicle type and with flexibility on how accurately the vehicle is positioned.

Gruzen said WiTricity’s technology is 91 percent to 94 percent efficient, and can be even more efficient than plugging in because it doesn’t need certain pieces of technology, like a DC-to-DC converter.

WiTricity’s DRIVE series of wireless EV charging pads come in 3.7 kilowatts, 7.7 kilowatts and 11 kilowatts -- typical sizes for consumer vehicles. The company also plans to scale to 22 kilowatts and higher to power bigger vehicles like electric buses. By installing charging pads at bus stops and depots, buses may never have to plug in or fill up again.

Some of the first applications of wireless chargers will likely be for luxury vehicles, like the S550e, until technology the technology scales and costs come down. Ditching the plug may seem like a luxury, but the convenience factor is actually considered an important draw to electrification in general.

Nissan is partnering with WiTricity because of “the potential of wireless charging to help advance widespread acceptance of EV motoring," said Kazuo Yajima, global director of the EV engineering division at Nissan.

Enabling the use of EVs is an important goal, said Gruzen. Wireless chargers significantly improve the user experience and are theoretically capable of bidirectional charging and other applications that benefit the electrical grid. But the evolution of autonomous vehicles is what caused interest in wireless charging to really spike.

"It's like there’s a holy trinity of electrification, autonomy and shared services…and in the middle of that is all the investment that's taking place in lidar and in optical sensors like from Mobileye and Velodyne,” said Gruzen. “You’ve also got massive investments in artificial intelligence and machine learning, as well as optical processing and all of that decision-making. And, then, wireless charging.”

“Not as many people are talking about [wireless charging], but there just aren't going to be fleets of autonomous Ubers…without wireless charging,” he added.