You might yet be able to untether from your power cords. This month has seen the debunking of a proposed long-range method of wireless charging, but almost simultaneously, a simpler and efficient method for charging laptop computers quietly went into production.
The bad news was for UBeam, which had long earned skepticism on its claims that it could build a device to wirelessly charge your smartphone or other device from meters away using high-frequency sound waves. The company attracted $24 million in venture investment and publicity coups like this unquestioning New York Times piece. Then Paul Reynolds, a former engineer at UBeam, published blog posts basically saying the project—which has never shown a working prototype—has achieved little and can’t work. Ubeam has not replied to the accusations.
Meanwhile, a system developed by Witricity is fast advancing. This version uses magnetic resonance. A current is passed through a coil to generate an electromagnetic field, which creates another electric current in a coil in a nearby device.
Some existing products use a simple version of this method, but both coils have to be positioned very closely together, requiring a special pad. In Witricity’s version, called “highly resonant magnetic induction,” the sending and receiving coils are tuned to resonate at a specific frequency, allowing charging at larger distances. This means that charging pads can be bolted beneath existing surfaces such as desks or counters.
Witricity’s design is now headed for manufacturing lines. “Just last week we were in production in our factories. Our customer products are now being built,” says Alex Gruzen, Witricity’s CEO. He wouldn’t mention the product, but says: “We have a large collaboration with Intel and major notebook computer makers.”
There is an energy penalty, however—the systems for laptops and phones are only 70 to 90 percent efficient, depending on how they are used. But Gruzen says the real sweet spot for the technology might be to help charge electric cars. When cars are parked above a coil, he says, they can be charged with an efficiency of 92 to 94 percent—around the same as wired charging, which carries losses in the lines and voltage system. The system is slated to be available in an electric car next year.
Gruzen says he’s long been a UBeam skeptic. “I never believed the physics of the ultrasound method, at least in terms of the claims they were making."
A consortium of wireless power system makers, the Wireless Power Consortium, agrees, basically saying over-the-air recharging for consumer devices is “impossible.” “Power through the air is possible today for industrial ultra-low power applications,” it said in a blog post. “Mobile device charging through the air will remain impossible for the foreseeable future.”