Airnergy's Wi-Fi power harvester: Is it real or not?

Critics say converting Wi-Fi to power needs to be more efficient to work

Airnergy, a Wi-Fi hot spot power harvester under development by Audiovox Accessories Corp., is either an intriguing green power technology for smartphones or complete alchemy, depending on whom you ask.

A prototype of the device was shown at International CES in the Audiovox booth, and stories and blogs filtered out afterward based on video-recorded descriptions of Airnergy performed by Audiovox employees. The product uses the well-known RCA brand name, which is owned by Audiovox, a spokeswoman said.

As described, the small 2 in. x 3 in. device would harvest Wi-Fi energy emitted from access points in a hot spot, turn it into DC power and then store it for use in a small device. A BlackBerry Bold was charged from 30% to 100% in 90 minutes using the device, according to the video by

It is expected to ship this summer for $39 to $49, and in 2011 a version would be reduced in size to fit into the space for a battery in a smartphone, the Audiovox demonstrator said in the video.

But as soon as the stories including the video from CES appeared, a barrage of critiques appeared on various blogs and comment sections, including on Computerworld, where one man named Matt intoned that the story about Airnergy had to be an April Fool's Day joke several months early.

"Puh-lease!," Matt wrote. "This can't possibly work in any truly useful fashion...This is right up there with adding acetone to your gas tank to improve mileage."

Others commented on Computerworld's Web site and elsewhere that the Airnergy product would have to sit atop an access point to harvest enough DC power from the microwaves being transmitted. Generally, the critics acknowledged that radio energy can be transferred to DC power, but not reliably or in any significant amounts.

However, an Audiovox spokeswoman said in an interview today that the Airnergy product is still under development, but is real and was shown at CES. She said a press release announcing the product and some details is being prepared, possibly for release next week or, at least, "very soon."

Asked if she could describe the technical process for harvesting the power, she said, "My product guys would kill me," and also indicated that she had heard some of the criticisms.

"We've taken note of the comments," said the spokeswoman, Sandy Whicker. "You know how this business is. People see things very differently."

Some critics said that technology journalists, including one at Computerworld, had been taken-in by the Audiovox demonstration at CES.

"If you are a serious journalist you should recognize that some stories like this are scientific nonsense and are put out for publicity purposes. Serious journalists should be demolishing stories like this, not slavishly allowing themselves to be used in this way," wrote Roy Freeland, CEO of Perpetuum Ltd. in Southampton, UK, in an e-mail. Freeland said he is chairman of an international standards committee on energy harvesting that he did not name.

Freeland later explained that in a Wi-Fi hot spot, the maximum permitted radio frequency energy isn't potent enough to harm people and "would not provide anything like enough energy to do the recharging [Audiovox] claimed, with a device of that size which is 100% efficient."

He noted that Nokia was reported in June 2009 to be researching energy harvesting for use in cell phones. Nokia later said in a statement that it did not have a prototype energy harvesting device and would not speculate on whether the research would ever become part of its portfolio.

One wireless analyst, Craig Mathias of Farpoint Group, said that turning microwaves transmitted from Wi-Fi access points into DC power and storing it as the Airnergy product purports to do is physically possible.

But Mathias questioned how efficient, strong and reliable a Wi-Fi signal could be for use in harvesting into DC power.

"If Airnergy works, great," Mathias said in an interview. "Yes, it could work. The question is how efficient it is. But it is physically possible." Mathias collaborated on a tethered satellite experiment that involved dragging a metal cable behind the space shuttle in space at 15,000 miles an hour, which essentially became a generator of energy.

"It sounds to me that Audiovox has created an electrical circuit in the [Airnergy] box that is specifically tuned to a radio frequency that converts it to DC power. That is quite a technical feat," Mathias said.

The value of the Airnergy product would be its ability to replace charging a battery with a cord plugged into an electrical outlet, requiring the use of more electricity and adding to the carbon footprint, Mathias noted. "It's got the green cachet."

Some critics have questioned why a person would need Airnergy in a hot spot when power outlets would probably be nearby, but Mathias said the reason would be to use energy already freely available in the air, rather than draining it from an outlet and using electricity that has to be produced, often from fossil fuels.

Audiovox would not say if it holds a patent on the Airnergy device, and a search on the U.S. Patent and Trademark Office site did not yield any results for "Airnergy" or "Wi-Fi Hotspot Power Harvester" and related terms.

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