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Wireless power transmision

  1. May 28, 2008 #1
    i was reading about a wireless energy transfer system using antennas with long-lived resonance under development by MIT (google 'wireless power MIT' to find explainations of technology). i understand enough about the workings of this system i was wondering if anyone knows anything about when it might be on the market?

    while on the subject what interesting applications can people think up for this technology?

    i can think of the more obvious ideas such as charging your mobile whenever in range of one of these antennas. my other idea is a bit more ambitious but you could power a car wirelessly if there where enough of these systems within a town masively reducing the weight if an electrical vehicle and therefore performance and efficiency. obviosly you couldnt go out of range of an antenna or the car would stop but this could work for a bus around a city or trains.

    what are other peoples ideas?
     
  2. jcsd
  3. May 28, 2008 #2
    The idea has been around for a while, I think it was Tesla's baby. It would be great, I freakin hate the rats-nest of various cords around my desk at the moment.
     
  4. May 29, 2008 #3

    russ_watters

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    I have a cordless toothbrush with no direct electrical connection to its base station. I can forsee putting a cel phone on a charging pad, but because of the way electromagnetic energy spreads out when transmitted, you are unlikely to ever see applications that function beyond a few inches - and even then, at horrible eficiencies.

    Remember, these ideas of Teslas were fundamentally just transformers and radios. A radio station puts out kilowatts or megawatts of energy and the receivers capture microwatts of it. It is possible to build a self-powered radio (crystal radio), but they don't put out enough sound energy to be useful as more than an interesting project.

    You can make radio more directional with shorter wavelengths and even phased-arrays, but these might increase your efficiency by a couple of orders of magnitude (so, providing miliwatts instead of microwatts), but they are directional and phased arrays require line of sight and active tracking.
     
    Last edited: May 29, 2008
  5. May 29, 2008 #4
    i know the toothbrushes and the charging pad are available but the system i heard about uses electromagnetic resonance. similar to a radio antenna except masively more efficient. the charging pads and the toothbrush work using the same principle as a transformer but this is only efficient at very short range. the MIT design is efficient up to a few meters away. i know tesla worked on longer range systems but i dont believe the work he did was as cheap or adaptable for home use as the MIT idea. i just think such a simple, cheap, and useful idea has got to make it to the market and was wondering when it might happen. maybe someone knows enough about electrical technology and the design process of these sorts of things to give an idea of how long it will be.
     
  6. May 29, 2008 #5

    berkeman

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    The most recent hit that I got with the google search is about a year old. Interesting read, but curious that nothing seems to have happened in the past year. Maybe they realized that there was enough leakage to the surrounding environment to cause FCC rules violations for practical power exchange levels. Do you have more recent links? You can PM them to me and I'll post them if you aren't able to yet.

    http://www.physorg.com/news100445957.html


    .
     
  7. May 29, 2008 #6

    f95toli

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    I've read the paper they published. It was an interesting demonstration and there might even be some applications. However, it was still very inefficient compared to a cable and safety will always be an issue, even if you use a very narrow "resonance" (linewidth) to transfer the energy we are still talking about EM waves and a powerfull transmitter; something that can never be made to be complettely safe for home use (not to mention all the EMC issues).
     
  8. May 29, 2008 #7

    russ_watters

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    I always get skeptical when peopel talk about resonance in such context. "Tuning" a radio is matching the resonant frequency to the radio transmission. There is no other context that I'm aware of fo it here. But when talking about Tesla, people tend to see the amplification of a signal as an amplification of energy. It isn't. There is no free lunch.
     
  9. May 29, 2008 #8
    Correct me if I'm wrong, but I think I remember in Tesla's biography that this is what he was trying to do later in his life, at Weycliffe on Long Island and Colorado springs too, matched frequency resonators for wireless power transmission. Wireless power transmission was always his dream. He was an interesting character, loved the pigeons in NY.
     
    Last edited: May 29, 2008
  10. May 30, 2008 #9
    I had an old NASA spinoff publication from the seventies. One of the spinoffs is a solar power plant in space which would collect energy and transmit it the energy back to earth using micro waves. The only problem is the high cost of getting things into space.
     
    Last edited: May 30, 2008
  11. May 30, 2008 #10

    russ_watters

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    ....and the occasional flock of geese flying through the beam.
     
  12. May 30, 2008 #11
    what interesting applications can people think up for this technology?


    Hmmmmm

    The Mars lander could use some beam down energy in a few months.
     
  13. May 30, 2008 #12

    berkeman

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    Do geese taste like chicken? :wink:
     
  14. Jun 2, 2008 #13
    I'm pretty sure i saw an ad somewhere about charging cell phones and walk mans this way, but you had to put them on this padded area, so they had to be pretty close to the source.


    The toothbrush I believe is just half a transformer in the base and the other half on the charging unit.

    I have seen one application though at our school we have these digital drawling pads I can't think of what they are called because it's 4am but it was a pad and a pen and you would draw on it and it acted like a mouse, so you could draw on it and draw in MS paint. But the pen for it was not connected to anything, and I was wondering how it work so I googled the name of the product and it uses this technology. I thought this was weird though because it was in an electronics lab and I would think they would cause some noise (they were like two feet away from our scopes and other equipment)
     
  15. Jun 3, 2008 #14
    I don't see why that is a problem. Starving people will see cooked geese fall from the sky as if it were a miracle.
     
  16. Jun 20, 2008 #15
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