Harvesting RF energy

From Erica Ogg on c|net:

A Pennsylvania start-up says it has the answer to one of the biggest problems in mobile phones: battery life. After three years of keeping its technology under close guard, Powercast has come to CES 2007 to get consumer and manufacturer attention. Powercast is a radio frequency that is transmitted over a small area, and its energy is "harvested"--wirelessly--to give power to small devices like cell phones.

While it's presented as wireless power, Powercast isn't just a replacement for a universal charger. Instead, it's meant to either continuously charge a battery or replace the need for them altogether. It works like this: a transmitter can be placed anywhere--in a lamp, for example, that is plugged into the wall and sits on a table. The transmitter in the lamp sends out a continuous, low RF signal. Anything with either AA or AAA batteries set within its range--and equipped with a Powercast receiver, which is the size of your fingernail--will be continuously charged.

"Our solution is, if talk time (on a cell phone) is 5 1/2 hours, by trickle-charging (it) at work, now talk time is 10 hours because the battery never gets to dead," John Shearer, CEO of Powercast, said in an interview. There are many applications for Powercast, said Shearer, but the company is making the PC peripherals market a priority. Think a wireless keyboard or mouse with no battery, or a hermetically sealed battery that the customer never need access again. Major CE and IT manufacturers will have to agree to build Powercast capability into their products, and thus far Powercast is revealing only Philips as a future partner. The first Powercast product will come to market by the end of 2007, the company says.