Revolutionize Charging with RCA Airnergy: Harness WiFi Energy Harvesting!

In summary, the Airnergy by RCA claims to be able to scavenge enough energy from WiFi (and presumably the 2.4GHz band) to juice up its own internal battery and allow a user to charge up devices on the go. However, the system is claimed to be inefficient and has negligible potential to power devices.
  • #1
MATLABdude
Science Advisor
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A little gizmo with one heckuva claim was demonstrated at the Consumer Electronics Show (CES) recently. The Airnergy by RCA claims to be able to scavenge enough energy from WiFi (and presumably the 2.4GHz band) to juice up its own internal battery and allow a user to charge up devices on the go:
http://m.gizmodo.com/site?sid=gizmodoip&pid=JuicerHub&targetUrl=http%3A%2F%2Fgizmodo.com%2F5444850%2Frca-airnergy-charges-gadgets-with-nothing-but-wifi-signals%3Fop%3Dpost%26refId%3D5444850

Perhaps this should be in the Product Claims subforum, but I can't imagine how long it'd take to build up even a few dozen mAh of charge with 40 mW routers. Perhaps as an emergency, always available source, but as something used on a regular basis? I don't know if I buy it.
 
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  • #2
Sounds like total nonsense.
Bear in mind
1. the efficiency of the Router transmitter, in terms of total power supplied vs actual transmitted RF power and
2. The loss of power over the RF link (assuming you're not in an ellipsoidal reflecting box with Tx and Rx at the foci)

How much significant energy could the system POSSIBLY yield?
 
  • #3
I agree that it sound fishy, But there are a number of companies working on this and some of them have a pretty good reputation when it comes to innovations I might be wrong but I think I've read somewhere that Nokia are working on something similar and have already demonstrated a prototype It wouldn't give you enough energy to actually charge the battery if it it was empty, but the claim is that this technique might improve battery life somewhat.
 
  • #4
Despite their possibly good reputations you can't argue with the figures, can you? You're talking tens or hundreds of microWatts, tops, when you're close to the transmitter. Let's face it - they use a receiver with an amplifier, to produce enough power to detect and decode the actual WiFi signal. Why would they bother, if there was enough received power to operate a "crystal set'?
A much better potential source of energy would be movement (like kinetic watches) or thermal.
 
  • #5
But there are quite a few devices that only require a say 100 uW in standby-mode, and for those it might be a useful technique for extending battery life; at least when combined with a battery.

Also, the "harvester" would presumably be a separate circuit, it would obviously not make sense to operate it while using an amplifier at the same time so the rest of the RF circuitry would have to be in standby mode when using the harvester (and maybe only respond to a very simple and strong "wakeup" signal).
 
  • #6
This feels wrong to me. The maximum permitted radiated power from a WiFi device is, according to Wikkers, 100mW and this would be radiated omnidirectionally, more or less. It would be very lucky to get as little as 30dB of loss between transmitter and receiver - without my silly scenario or a dedicated, directional antenna at each end. This would make even a modest 100uW much too much to hope for.

When you think that 100uW is the sort of power that a tiny battery would give you for months, in any case, I really question it as being worthwhile, at all. It is insignificant compared with the load which the 'main' equipment would be needing - even for a few minutes at a time (we're looking at very esoteric applications here, at best and not a domestic scenario). A device which would need to run for a long time without attention would be, necessarily, a long way from a base station and be receiving the very minimum of signal strength.
There are occasional threads on fora about 'wireless power transmission' and this seems to be another of the same. We could just as well discuss the possibility of having a Radio receiver which we could use once in a blue moon which is operated by off-air power. Anyone who has made a crystal set will know that you need a pretty huge aerial installation to get energy out of the Aether. That tends to be true whatever frequency you are working at.
 

1. What is WiFi energy harvesting?

WiFi energy harvesting is the process of capturing and converting the radio frequency signals from WiFi routers and other wireless devices into usable electrical energy. This energy can then be used to power small electronic devices such as sensors, wearables, and IoT devices.

2. How does WiFi energy harvesting work?

WiFi energy harvesting works by using an antenna to capture the radio frequency signals emitted by WiFi routers and other wireless devices. The captured signals are then converted into usable electrical energy using a rectifier and a power management circuit. This energy can then be stored in a battery or used to power electronic devices.

3. What are the advantages of WiFi energy harvesting?

There are several advantages of WiFi energy harvesting, including its ability to provide a renewable and sustainable source of energy, its low cost and easy installation, and its potential to power small electronic devices without the need for batteries or external power sources.

4. What are the limitations of WiFi energy harvesting?

One of the main limitations of WiFi energy harvesting is its limited range, as it can only capture signals from nearby WiFi routers and devices. Additionally, the amount of energy that can be harvested is relatively small, making it suitable for low-power devices. The efficiency of WiFi energy harvesting also depends on the strength of the WiFi signals, which can vary in different environments.

5. How is WiFi energy harvesting being used in real-world applications?

WiFi energy harvesting is still a relatively new technology, but it is already being used in various applications. Some examples include powering environmental sensors in smart buildings, powering wearable devices, and extending the battery life of IoT devices. It is also being explored for potential use in wireless charging and wireless power transfer systems.

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