Do we need roads that charge cars? Detroit thinks so

Electric car drivers in Detroit can soon boost their batteries just by driving down the right road.

On Wednesday, Michigan state agencies awarded $1.9 million to Israeli startup Electreon to build a mile-long wireless charging strip. The chargers will lie under a street in Detroit’s Michigan Central district, an innovation hub for clean and autonomous mobility tech. 

Wireless car charging works through electromagnetic resonance. A car equipped with a special receiver simply positions itself over a copper coil transmitter, which beams up energy from below. It’s similar to wireless phone charging, but souped up to transmit across the gap between the road surface and the underbelly of the vehicle.

This technology works in stationary settings where a transmitter sits under a parking space, taxi stand or bus stop. But it also breaks open the possibility of dynamic charging, in which charging strips built into roadways refill car batteries as they move or sit at red lights.

“The system allows you to charge on the road while driving or standing still,” said Stefan Tongur, Electreon’s VP of business development for the U.S. ​“If you adopt this at the right places, it makes a huge difference.”

Refuel from the road

Despite the futuristic sound of beaming energy through the air, this technology exists today. Several startups have trialed their wireless chargers, including Electreon, Hevo, Lumen Group, Momentum Dynamics and WiTricity.

But finding an active charging roadway in the wild is still a rare feat. Tim Slusser, Detroit’s chief of mobility innovation, called the Electreon project a ​“first-of-its-kind deployment in the U.S.”

Detroit’s pilot project, funded by state grant money and an unspecified investment from Electreon, should be installed by 2023. 

Construction involves stripping the surface of the road, laying down the transmitter coils and wiring them up, and pouring a new asphalt surface. That process moves pretty swiftly, Tongur said, at around 1 kilometer of roadway per day. 

Electreon isn’t worried about having to rip up the street later to make repairs, he added. The coils are ​“smart and modular,” so if one unit fails for some reason, the rest of the roadway will keep charging along.

To tap into roadway charging, EVs need to be outfitted with wireless charging receivers. Electreon’s receivers typically absorb 25 kilowatts of instantaneous power — more than a typical Level 2 charger plug, much less than a DC fast charger. A ride down a mile of the road won’t allow time for a proper fill-up. The point of the pilot project is to prove the concept that driving doesn’t have to deplete a car battery — it could actually replenish it.

Shooting energy through the air near drivers and passengers may raise health concerns. Electreon takes those seriously and has already gone through rigorous vetting, Tongue said; a project in Sweden, for example, had to clear independent scrutiny by seven different government agencies.

“It’s been tested, it is safe, and there are standards already in place regulating this field,” Tongur explained. 

Automatic charging for the people

Installation is the easy part; all the other steps will take more time. 

The wireless charging industry has agreed to a universal standard for stationary charging of light-duty vehicles, so all cars and chargers work over the same frequency, Tongur said. But standards still need to be hashed out for heavy-duty vehicles and for dynamic roadway charging, he noted. A universal standard would allow personal cars, buses and trucks to all tap the same roadway charging.

Wireless charging receivers are not yet a standard offering in EVs rolling off the dealer lot. Ford is involved with Detroit’s project, suggesting it will enable some compatible cars. 

More broadly, Electreon envisions the switch to wireless charging starting with fleets, including transit vehicles, delivery trucks, ride-share cars and taxis, Tongur said. Installing chargers along regular routes would mean some fleets could recharge as they go, instead of having to spend hours each day charging empty batteries.

“You need to start and get volume with some sort of target fleets,” Tongur said. ​“The long-term potential is for the public.”

In other words, fleets can benefit from strategically sited charging roadways right now. And once the roads are built, other people could access them too. 

Wireless charging would have big ramifications at the societal scale. 

The current trajectory has us putting ever-larger batteries in EVs so drivers can avoid annoying charging sessions, and then straining the grid with ever more energy-sucking fast chargers to fill those big batteries quickly. In contrast, wireless charging could make small batteries perfectly capable of fulfilling a driver’s needs. If you end up with more juice at the end of a trip than at the beginning, range anxiety disappears.

The ability to refuel on the run is also a convenience that combustion-powered cars could never deliver — a useful differentiator for convincing new customers to take the plunge on an EV.

As Electreon puts it in its marketing materials: ​“No need to stop for charging.”

Future-proofing billions of dollars in charger investment

Detroit’s next-generation charging pilot comes as the U.S. and other nations are spending billions of dollars to install the current generation of wired EV charging ports. 

The U.S. infrastructure law passed last year directs up to $7.5 billion to help states build EV charging infrastructure. Just this week, renewables powerhouse NextEra Energy Resources teamed up with investor BlackRock and Daimler Truck North America to collectively spend $650 million building carbon-neutral freight charging and fueling infrastructure, starting this year.

But as anyone who’s owned a smartphone for a few years can attest, charging technology changes with time. 

“Wireless is a new entrant in this field,” Tongur acknowledged. ​“With all that money being spent now by the government…wouldn’t it be smart for the U.S. to secure a future-proof technology?”

Current vehicle chargers have clear drawbacks. Not all EVs can use all chargers, a headache caused by the heterogeneous array of plug designs employed by automakers today. More mundane issues include drivers bumping into chargers and disabling them, as well as other forms of wear and tear.

There’s no harm in running over a wireless charger — that’s exactly what you’re supposed to do. Embedding chargers in the pavement means they don’t have to take up space on sidewalks or in parking lots.

Conventional fast chargers create spots on the grid that often experience sudden surges in electricity demand, especially in the case of a large bus or truck depot. But wireless charging ​“distributes energy over time and space,” Tongur said. The coils only draw power if a properly equipped car is positioned above, and each Electreon receiver typically draws just 25 kilowatts (larger vehicles can add multiple receivers for more power).

Rep. Brenda Lawrence, a Michigan Democrat, is already working on a bill to allocate $50 million of federal grants for wireless charging pilots, The Detroit News reported Thursday.

Wireless charging roadways should not be confused with similar-sounding solar roadways. Solar roadways captured mass public attention and approximately zero percent market share after a crowdfunding campaign in 2014. 

Building solar panels capable of withstanding the weight of an 18-wheeler is a very expensive way to produce carbon-free electrons, which are readily available from many cheaper sources. Wireless-charging roadways are paved like normal roadways and absorb wear and tear like normal roadways. But they provide an otherwise unavailable service: refueling while driving.