is it possible to generate electricity from air?

Discussion in 'General Electronics Chat' started by INS-ANI, Aug 15, 2008.

  1. INS-ANI

    Thread Starter New Member

    Aug 15, 2008
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    Hi guys,
    i need some advice on using the various airwaves in air(including Wifi waves) to generate some electricity. and if it is possible to charge mobile.
    I heard somewhere that it is possible to charge mobile by infrared. I am not sure how it works. we have a mini project in our third year of engineering. I need advice for the same.
    If any 1 of u have some detail regarding this , pls post here.
    thankyou
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    The radio waves that surround us don't have enough energy to be used to charge batteries or power anything and wi-fi is very low power. Microwaves can be used to transmit power but the power levels involved would be fairly lethal for anyone that gets in the way.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    Seems I read an article on Edn.com in their Design Ideas section several months back that some fellow wrote - he was using the sounds from the street to charge a supercapacitor by using a piezo element and rectifying the output voltage.
     
  4. INS-ANI

    Thread Starter New Member

    Aug 15, 2008
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    would u please direct me to the link.
    Actually i am more intrested in displaying the wireless charging. I may even use a 500w bulb to provide the required light to the photosensor. or i may even use electromagnetic fields from a source to receiver to do the same.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    It's on EDN.Com somewhere. You will need to search for it yourself.
    [eta]
    Title of the article:
    "Harvest energy using a piezoelectric buzzer"
    Page 94, EDN, March 20, 2008

    Not likely you'll be able to power a 500w bulb with the energy you're able to harvest. 500nW, maybe.
     
    Last edited: Aug 16, 2008
  6. Wendy

    Moderator

    Mar 24, 2008
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    The real problem is power densities, there just isn't much out there. Makes sense if you think about it, it would be waste product.

    I have heard stories about people tapping into the EMF from high tension lines, but the stories always end up with them being busted by the power company, and possibly going to jail.

    Think natural resources, solar, wind, geothermal, tides and/or waves. Unless it is truly a waste product, such as sound, you are likely going to tick off the person who created and owns the resource you're using for energy. There isn't free lunch, if you use radio waves to generate power then someone else (who has a legitimate use) won't be able to use them for their intended function.
     
  7. INS-ANI

    Thread Starter New Member

    Aug 15, 2008
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    i totally agree with u Bill, and thanks for advicing me to think on the line of natural resources.
    Now i will come back after researching the feasibility of solar cell,photoelectric sensors, etc
     
  8. cumesoftware

    Senior Member

    Apr 27, 2007
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    I think using radiation as a way to transmit power is not a good idea. You will have power losses in the range of 80% or more. This has been discussed before.

    Of course you didn't mentioned anything about power losses, but the idea is there. I hope you understand my point of view.

    Power density is another issue. In order to transmit power effectively you would need a LASER, and all the problems underlying there (proper heatsinking, etc).
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    I have heard stories about people next to commercial radio stations using their power, but my arguement above still applies.
     
  10. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    All it takes is a ditch witch, a few hundred feet of cable, and a tap on the commercial radio station's power feed.

    Of course the next in sequence would be landing in jail for theft.
     
  11. Wendy

    Moderator

    Mar 24, 2008
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    I was thinking more of a 100ft antenna within a mile of a commercial AM radio station, say a class one. There the legalities get a little complicated. I suspect at the least they can sue in civil court, but recievers aren't as rigidly controlled by FCC rules as transmitters. At most you would get is a watt or two though, power densities again.

    Back in my learning days I regularly feed 50 to 100ft of wire (the whole spool) between trees for my crystal radio. There I was using the radio waves to power my earphone. Same thing, but completely legal, and the station I was listening to would approve.
     
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