Wireless Power

July 23, 2009

Almost everyone who has ever traveled with even a subset of his collection of electronic gizmos knows about the annoyance of carting along power adapters and battery chargers, and of trying to find replacement batteries in an unfamiliar place.  Today’s BBC News has a report from the TED Global Conference about a new technique for the wireless transmission of electric power.

Eric Giler, chief executive of US firm Witricity, showed mobile phones and televisions charging wirelessly at the TED Global conference in Oxford.

He said the system could replace the miles of expensive power cables and billions of disposable batteries.

Of course, the idea of transmitting energy without wires is not new: the microwave over in your kitchen, and radio and TV broadcasts do it all the time.  Both Edison and Tesla explored the idea of wireless power transmission in the early days of electricity.  The trick is to do it without “cooking” everything nearby.

The new system works by using a technique based on magnetic resonance, developed by an MIT physicist, Professor Marin Soljacic.  Both the power transmitter and receiver have antenna coils that are tuned to the same resonant frequency.  The system uses a long wavelength (about 30 meters), so that near field effects (less than one wavelength from the source) predominate; the power is transferred via changes in the magnetic field, and the electric field strength is minimal.  Suitably equipped devices would begin to recharge themselves as soon as they came close to the power transmitter.

Of course, our existing wired electricity infrastructure is not going away anytime soon.  But it’s possible to imagine a range of uses for this technology:

Mr Giler said Witricity’s approach could be used for a range of applications from laptops and phones to implanted medical devices and electric cars.

I use  a laptop a lot more these days than I did a decade ago, even at home, because the advent of WiFi means I don’t have to be tied to a network cable.   Getting rid of the power cord would make things even easier.

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