FCC filings spotted by IEEE Spectrum suggest that Google is in the process of installing wireless charging systems at its headquarters campus and the nearby Castle facility — a former Air Force base where the company tests its self-driving cars.

The documents point to installations from Hevo Power and Momentum Dynamics, both of which offer offer systems that can charge cars, trucks, and buses using plates that sit on (or embedded in) roads and driveways, while a receiver attached to the underside of the vehicle takes the power and siphons it into the battery pack. In principle, they're not much different than the wireless charging systems for phones — just on a much larger scale. (Momentum, for instance, says its systems can deliver up to 200 kilowatts of power.)

In the short term, wireless car charging is seen as a home / office product — park your car overnight or during the workday and don't bother plugging it in, basically — but companies like Qualcomm have variously suggested over the years that wireless chargers could someday be embedded in public roadways, enabling cars to stay charged even as they drive.

The implications for Google's cars are particularly obvious, especially during the testing phase where all of the vehicles are traveling between known waypoints and a home base. Even as the company eventually expands to commercial use (or commercial partnerships), early deployments will likely be on closed campuses where wireless charging pads would be easy to install in known locations.