How One Japanese Smart City Is Bringing Wireless EV Charging to the Road
By integrating wireless EV chargers at traffic lights, a Japanese city hopes to blend dynamic and static wireless charging.
Wireless electric vehicle (EV) charging is gaining traction as a viable alternative to traditional plug-in methods thanks to its ease of use, accessibility, and versatility. Yet, the real goal is to integrate wireless charging into the roadway so vehicles can charge even as they drive.
The Kashiwa-no-ha Smart City. Image used courtesy of USGBC
Now, a Smart City in Japan is taking a big step toward this dream with a pilot program to test the integration of EV wireless chargers at traffic lights.
Wireless Charging for EVs
At its core, wireless EV charging employs resonant electromagnetic induction to transmit electrical current between a magnetic coil in the charger and a corresponding coil on the vehicle's underside. This technology is efficient, with ratings comparable to most EV plugs, and has the potential to deliver charging power up to 20 kW, equivalent to Level 2 charging speeds.
Wireless charging mechanism in an EV. Image used courtesy of Plugless Power
There are largely two forms of wireless EV charging: static and dynamic.
In static charging, the vehicle is stationary while it charges. The wireless-equipped EV is parked over an installed wireless charging coil in a designated space, usually at home or an office. This eliminates manual plugging and unplugging, offering a more convenient and streamlined charging experience. Static charging is particularly beneficial for commercial vehicles that return to a central hub at the end of the day, allowing for automated overnight charging without manual intervention.
Static wireless charging. Image used courtesy of ResearchGate
Dynamic charging, on the other hand, aims to integrate wireless charging coils into roadways. This would enable EVs to charge while in motion at up to speeds of 65 mph. Dynamic charging has the potential to revolutionize long-distance EV travel by continuously topping up the vehicle's battery, thereby eliminating the need for extended charging stops and effectively eradicating range anxiety.
The Kashiwa-no-ha Smart City
Recently, Japan has been looking to blend the best of both dynamic and static wireless charging through its pilot program at the Kashiwa-no-ha Smart City near Tokyo.
Specifically, the pilot program tests the feasibility and efficiency of wireless charging for electric vehicles at traffic lights. Spearheaded by the University of Tokyo, the project involves embedding precast charging coils into the road surface in front of traffic lights. When a vehicle with a special device near its tires rolls over these coils, it receives a wireless charge, adding about 1 km (0.6 miles) of range for every 10 seconds spent over the coils.
What makes this pilot particularly exciting is its potential to redefine urban mobility and EV charging paradigms. Traditional charging methods often require dedicated spaces and extended periods, which can be inconvenient for users and challenging to implement in densely populated areas. The Kashiwa-no-ha initiative, however, turns this notion on its head by integrating the charging process into the natural flow of traffic. By capitalizing on the time vehicles spend waiting at traffic lights, the technology creates opportunities for energy replenishment.
This not only makes efficient use of time but also could alleviate range anxiety, a significant barrier to broader EV adoption.
A Big Step for Wireless EV Charging
The Kashiwa-no-ha Smart City pilot program marks a major step forward in developing wireless EV charging.
While the pilot focuses on wireless charging at traffic lights, its implications extend beyond this specific application. For example, the data collected from this pilot could serve as a basis for developing smart grids that incorporate EVs as mobile energy storage units, contributing to grid stability and facilitating the integration of renewable energy sources.
Moreover, the success of this pilot could catalyze similar initiatives globally, inspiring cities to rethink their approach to sustainable mobility. As we navigate the challenges of urbanization and climate change, such efforts will be crucial in shaping cities that are not only smart but also sustainable.