Wireless Electricity is Here
Fast Company reports that Wireless Electricity is Here (Seriously). That’s … incredible.
After more than 100 years of dashed hopes, several companies are coming to market with technologies that can safely transmit power through the air — a breakthrough that portends the literal and figurative untethering of our electronic age. Until this development, after all, the phrase “mobile electronics” has been a lie: How portable is your laptop if it has to feed every four hours, like an embryo, through a cord? How mobile is your phone if it shuts down after too long away from a plug? And how flexible is your business if your production area can’t shift because you can’t move the ceiling lights?
As the article mentions, the physics of how to do this has been understood for a while. But the ability to do this in a way that works well and is useful has not existed before. There are about three different approaches coming to market. Here’s how one of them works:
A powered coil inside that pad creates a magnetic field, which as Faraday predicted, induces current to flow through a small secondary coil that’s built into any portable device, such as a flashlight, a phone, or a BlackBerry. The electrical current that then flows in that secondary coil charges the device’s onboard rechargeable battery. (That iPhone in your pocket has yet to be outfitted with this tiny coil, but, as we’ll see, a number of companies are about to introduce products that are.)
For more detail, here’s a helpful summary from an article at Popular Science:
Scientists have known for nearly two centuries how to transmit electricity without wires, and the phenomenon has been demonstrated several times before. But it wasn’t until the rise of personal electronic devices that the demand for wireless power materialized. In the past few years, at least three companies have debuted prototypes of wireless power devices, though their distance range is relatively limited [see "Power Brokers," next page]. Then last year, a team at the Massachusetts Institute of Technology set the stage for wireless power that works from across a room.
The key to wireless power is resonance. Think of a wineglass that shatters when an opera singer hits just the right note. When the voice matches the glass’s resonant frequency—the tone you hear when you tap the glass—the glass efficiently absorbs the singer’s energy and cracks. Using magnetic induction and two identical copper coils that resonate at the same frequency, the MIT scientists successfully powered a 60-watt lightbulb from a power source seven feet away. The team called their invention WiTricity, short for “wireless electricity.” Next up: sending the juice even farther and more efficiently.
You can also read more on wireless electricity at Wikipedia.