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RCA Airnergy claims to charge gadgets using ambient WiFi signals

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January 12, 2010

The RCA Airnergy harvests ambient WiFi energy to charge your gadgets (Photo: OhGizmo)

The RCA Airnergy harvests ambient WiFi energy to charge your gadgets (Photo: OhGizmo)

Move over solar chargers. Step aside kinetic chargers. If RCA are to be believed, there’s a new way to scavenge power from your environment using an energy source that’s all around us: WiFi. If you are reading this article, the chances are very good that you are in range of at least one wireless network. RCA says its Airnergy Charger scavenges stray WiFi signals and converts them to DC battery power that you can use to charge your cell phone, music player, or other electronic devices.

RCA calls the Airnergy a “WiFi hotspot energy harvester”. The device is about the size of a cell phone, with a Micro USB connector hanging off it. Inside is an antenna to receive 2.4GHz (802.11) WiFi signals, and a converter that turns the WiFi energy into DC power which is then stored in the on-board battery. You can keep the Airnergy in your briefcase or your pocket and whenever it is within range of WiFi, it charges itself. Simply connect it to your device to charge its battery. And, unlike solar chargers, the Airnergy works at night.

At the CES 2010 show, RCA claims to have demonstrated the Airnergy charging a BlackBerry from about one-third to fully-charged in about 90 minutes. Naturally, the strength of the WiFi signal will affect how quickly the Airnergy can charge a device.

So is the Airnergy ready for prime time? We’ll definitely be keeping an eye on this technology, but RCA says they are already working on a new version that will be small enough to fit inside an OEM cell phone battery. With the Airnergy harvesting battery pack, you could recharge your phone or other device simply by leaving it range of a WiFi hotspot.

RCA is aiming to bring the Airnergy Charger to market in the third quarter of 2010, with an expected price of US$40.

Via: OhGizmo.

Ed note: While I attended CES, I did not witness this demonstration personally, nor did any other members of the Gizmag team at the event. Indeed, after discussing this, we find it hard to believe that enough energy can be gleaned from a Wi-Fi signal to provide a practical charging solution for mobile phones. It's certainly easy to be skeptical about the "one-third to fully-charged in about 90 minutes" claim. For now, we'll be putting this one in the "believe it when we see it basket".

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14 Comments

If I had to guess, I'd say that the 90 minute recharge time would be assuming the Airnergy's internal battery was already fully charged. I doubt very much you'd pull enough energy from the ambient wifi in that period of time, but if it had been trickle charging itself for the last 2 days it makes sense.

xenor
13th January, 2010 @ 06:19 pm PST

Do you really care how long it takes to charge if your are on near constant trickle charge.

David Fitch
13th January, 2010 @ 08:09 pm PST

In the EU the maximum legal Wifi transmission power is 100 milliwatts, however, on average 802.11 devices transmit at 50mw. Now in accordance with the inverse square law, at a distance of 5 meters, the power is reduced to 1 / (5^2) = 0.04 * 50mw = 2mw. Two milliwatts at 5 meters. Assuming they have a respectable electrodynamic induction efficiency of 75%, they will be able to convert 75% of that 2 milliwatts back into electricity: 1.5 milliwatts.

It takes 50 times that to power a single LED. This means that if their internal battery is 3 volts, 3000mAh it will take about 5000 hours to charge it to full capacity.

Gruph Norgle
14th January, 2010 @ 11:00 am PST

RCA is making this? This is the type of snake oil nonsense that I would expect from some unheard of company. I am definitely in the believe it when I see it camp with this one! I understand the basic principles, but to me I think it would take days upon days to actually charge something.

Brian R
14th January, 2010 @ 08:43 pm PST

Tapping energy from wireless signals should be quite feasible. I am sure the device does not depend only on the 2.4GHz of WiFi. In any case it is easier to make, and much more efficient, to have a broadband receiver that is picking up cellular (0.8-2.7 GHz)and other devices signals (possibly even TV signals in the ~1GHz).

There is quite a concentration of this kind of energy in an average urban space, probably enough to charge a battery over a period of, let say a day. The statement that it "turns the WiFi energy into DC power " is likely political. WiFi is operated by individuals and there is no claim for the energy emitted. Cellular and other transmissions might have other legal consequences.

Deliverator
16th January, 2010 @ 01:15 am PST

However impossible it seems this must be akin to "stealing" power from overhead power cables - by whatever means.

Wireless access points are provided for people to access the internet and the cost (including electricity that powers the access point) is borne by the customers of the location - be it a cafe or airport.

All that will happen is that (food/ticket) prices will be increased to cover the increased electricity consumption as everyone charges their handhelds from the access point.

I agree with Gruph Norgle who hit the nail on the head...

agulesin
18th January, 2010 @ 06:06 am PST

@Deliverator: you don't seem to realise just how little energy can be harnessed. Even with 10 devices all within 5 meters (16.5 feet) it would take 21 days to charge a battery.

Gruph Norgle
19th January, 2010 @ 07:18 am PST

This sort of nonsense is why we haven't seen devices to "harness the power of the AM and FM stations transmitting over the air", or "harness the power of the television broadcasts"...

About the only thing comparable is a crystal radio, which has barely enough power from the radio wave signal to hear the signal over a earphone... barely. Definitely in the milli/microwatt range.

We are awash in radiofrequency waves from all over the city, nation and world, and the solar system. Just no practical way to capture it and convert it to useable, practical battery power.

matthew.rings
20th January, 2010 @ 10:06 pm PST

At the end of the day, they would make hundreds of times more power if the just attached a solar panel.

Gruph Norgle
21st January, 2010 @ 02:29 am PST

@agulesin: Actually, the access point will transmit at 100mW no matter how many users are accessing it. If you had an airport terminal hotspot with 150 people using it to charge their batteries, the AP would not use any more electricity than it does at 3:00 AM when nobody is using it. This is the same idea as your local FM radio station. Every time a new listener tunes into their station, they do not have to turn up the RF transmit power to compensate. The transmitter does not get loaded down by the receivers, which is why the radio station has no idea how many people are listening unless they try to calculate based on the number of respondents to their call-in contests.

I do agree with you, however, that hotspot providers would likely charge an extra "convenience fee" or somesuch if they knew that tons of people were charging their batteries (even though it would not cost the provider a dime extra on their electric bill).

Brian R
21st January, 2010 @ 09:43 am PST

@Gruph, you need to actually consider more than just inverse square law. Free space path losses for isotropic (spherical radiation) sources are much worse.

From first principles, if you calculate the surface area of a sphere with radius 5m (4/3 pi r^2), divide the 50mW over that to get an energy flux per square meter, and then multiply by the cross-section area of that device, and use that as a factor on top, the 1.5 mW becomes more like 2uW (assuming 5 x 10cm device size) assuming perfect conversion from intersected flux to electrical power (which it wont be).

Not a usable amount of power at that range sorry. If you put the device right on top of the WiFi transmitter it might be able to absorb a usable amount.

Why do people even bother putting their (human) energy and time into things like this without doing the basic math first??? Hard to believe it's got to even press-release stage.

Journos - you should be able to do this math, and make a stronger statement. If in doubt ask an electrical engineer :)

Adrien
17th June, 2010 @ 09:48 pm PDT

doh, 4 * pi R^2 not 4/3. So multiply power by 3.... 6 uW. Still not usable at 5m

Adrien
17th June, 2010 @ 10:24 pm PDT

Such a gadget is feasible, if it "stole" energy from a mains source though; eg;

http://www.doobybrain.com/2008/02/03/electromagnetic-fields-cause-fluorescent-bulbs-to-glow/

I'd guess it would need a long "antenna" though - some conductive way to bridge the distance from earth to the source.

christopher
21st January, 2012 @ 03:56 pm PST

A broadband receiver is much more logical, even the radio waves from the sun could be harnessed.. Why focus on just WIFI when we are constantly being bombarded by radio waves from earth the suns the entire universe.. Harness that and I'll pay attention..

acyron
25th April, 2014 @ 09:36 am PDT
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