Thanks to the researchers at Nokia, some day, putting your cell phone in standby mode may no longer cause the dreaded vampire power. Vampire power is frequently described as pointlessly wasting electricity with little benefit other than a small red light and instant start-up. According to an article in the UK’s Guardian, Nokia is developing a mobile phone charging system which is able to power itself on nothing more than ambient radiowaves that constantly surround us. The Guardian article points out that old crystal radio sets and modern radio frequency identification (RFID) tags are powered purely by radiowaves. Nokia claims that it’s system is able to scavenge enough ambient electromagnetic radiation emitted from Wi-Fi transmitters, cell-phone antennas, TV towers, and other sources miles away to operate a cell phone. Individually the energy available in each of these signals is minute,  but by harvesting radiowaves across a wide range of frequencies it all adds up, said Markku Rouvala, one of the researchers who developed the device at the Nokia Research Center in Cambridge, UK..

Nokia’s device uses a wide-band antenna and two very simple passive circuits. The antenna and the receiver circuit are designed to pick up  frequencies from 500 megahertz to 10 gigahertz and convert the electromagnetic waves into an electrical current. The second circuit is designed to feed this current to the battery to recharge it.

“Even if you are only getting microwatts, you can still harvest energy, provided your circuit is not using more power than it’s receiving,” Rouvala told Technology Review. So far the researchers been able to harvest up to 5 milliwatts (mW). Their next goal is to get in excess of 20 mW, enough power to keep a phone in standby mode indefinitely. but not enough to actually use the phone to make or receive a call the researcher  says.  Rouvala says that his group is working towards a prototype that could harvest up to 50 mW of power, enough to slowly recharge a phone that is switched off.

Earlier this year, Joshua Smith at Intel and Alanson Sample at the University of Washington, in Seattle, developed a temperature-and-humidity sensor that draws its power from the signal emitted by a 1.0-megawatt TV antenna 4.1 kilometers away. This only involved generating 60 microwatts.  Smith says that 50 mW could require around 1,000 strong signals and that an antenna capable of picking up such a wide range of frequencies would cause efficiency losses along the way.

Harry Ostaffe, head of marketing for Pittsburgh-based company Powercast, which sells a system for recharging sensors from about 15 meters away with a dedicated radio signal told Technology Review, “To get 50 milliwatts seems like a lot.”

If Nokia’s claims stand up, then it could push energy harvesting into mainstream consumer devices and improve their environmental footprint. Steve Beeby, an engineer and physicist at the University of Southampton, U.K., who has researched harvesting vibrational energy, adds, “If they can get 50 milliwatts out of ambient RF, that would put me out of business.” He says that the potential could be huge because MP3 players typically use only about 100 milliwatts of power and spend most of their time in lower-power mode.

According to Technology Review. Nokia is being cagey with the details of the project, but Rouvala is confident about its future: “I would say it is possible to put this into a product within three to four years.” Ultimately, though, he says that Nokia plans to use the technology in conjunction with other energy-harvesting approaches, such as solar cells embedded into the outer casing of the handset.

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As I have chronicled in the past and here,  wireless power is a good solution looking for a way to be implemented. Wireless power has now hit the Gartner “Hype-Cycle.” According to the July 2009 Gartner Hype-Cycle, Wireless Power has just entered the “Peak of Inflated Expectations” zone and is still 5-10 years from mainstream adoption.  This technology  hold many benefits to the environment (less wasted electricty) and user convenience (how many propeirtrary power adapters do you have?), it is yet to be seen if consumer demand can over-come the inertia of the status-quo and the power of big money lobbying by the coal, nuclear and utilities. Right now my money is on the money.