Wireless transmission of electricity

  1. I was reading Nikola Tesla’s Inventions recently. I was really stunned to know that he transmitted electricity without wires in the year 1899.
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    When Nikola Tesla discovered alternating current (AC) electricity, he had great difficulty convincing men of his time to believe in it. Thomas Edison was in favor of direct current (DC) electricity and opposed AC electricity strenuously. Tesla eventually sold his rights to his alternating current patents to George Westinghouse for $1,000,000. After paying off his investors, Tesla spent his remaining funds on his other inventions and culminated his efforts in a major breakthrough in 1899 at Colorado Springs by transmitting 100 million volts of high-frequency electric power wirelessly over a distance of 26 miles at which he lit up a bank of 200 light bulbs and ran one electric motor! With this souped up version of his Tesla coil, Tesla claimed that only 5% of the transmitted energy was lost in the process. But broke of funds again, he looked for investors to back his project of broadcasting electric power in almost unlimited amounts to any point on the globe. The method he would use to produce this wireless power was to employ the earth's own resonance with its specific vibrational frequency to conduct AC electricity via a large electric oscillator. When J.P. Morgan agreed to underwrite Tesla's project, a strange structure was begun and almost completed near Wardenclyffe in Long Island, N.Y. Looking like a huge lattice-like, wooden oil derrick with a mushroom cap, it had a total height of 200 feet. Then suddenly, Morgan withdrew his support to the project in 1906, and eventually the structure was dynamited and brought down in 1917.
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    My question is why is this process not useful in today’s world?

    Sree
     
  2. jcsd
  3. berkeman

    Staff: Mentor

    For the same reason that we don't use microwave ovens with unshielded doors. Think about it a bit. What would be a disadvantage of blasting megaWatts of RF power around the neighborhood?:eek:
     
  4. Berkeman you got it. There would be a million problems, the bigest ones I can think of (other then the damage to us people and other livign things) would be the occurance of nodes in the RF. That would mean some places would not beable to get power, adding a transmitter to fill the node would just cause more nodes in other places. Also it would cause all kinds of interfearance to electronics.
     
  5. Gokul43201

    Gokul43201 11,141
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    Why do you think it would be useful ? We already have only about 5% loss through conventional power transmission lines. Why risk frying all the birds that fly in the transmission path ?
     
  6. dlgoff

    dlgoff 3,150
    Science Advisor
    Gold Member
    2014 Award

    Wasn't there an idea to beam down power (via microwave) from large orbiting solar arrays?
     
  7. Thank you very much for all your replies.
    If there is a way to transmit 1V to 24V wirelessly, in a home and surroundings (about 2000 to 13000 Sft), so many present day electronics can be used wirelessly or charged wirelessly. Like Laptop, printer, scanner, cell phone, land phone, Ipod, etc..
    As per Tesla's books, He lighted several florescent lamps wirelessly in a big seminar hall before institute of electrical engineers in 1893 in Ohio. He demonstrated this one to show AC current is possible and can be transmitted safely. I believe he might be demonstrated low voltage wireless transmission. No body hurt or injured during demo.
    Do you think this one is possible in today's world?

    One more thing, Funding (JP Morgan) was withdrawn to Tesla's project for his high voltage wireless transmission, because no metering is available for the wirelessly transmitted or used electricity as of that day. Institute of electrical Engineers or JP Morgan (Investor) or Tesla's books did not mention about killing of birds or trees or humans during his research in Colorado Springs

    Ksree
     
  8. russ_watters

    Staff: Mentor

    How is that a good thing? You'd cook yourself while powering your laptop on your lap!
    How far were the lights from the source? Did anyone try getting between the source and the lights?
    Certainly, but the relevant question is is it generally useful in the type of applications you are describing? And the answer to that question is no.
    I'm not sure if that is true or not, but I know a lot of conspiracy theorists say it. I'm not sure of the relevance of it, in any case. Conspiracy theorists like to say that the ideas/research were suppressed, but that's nonsense.
    And why would they?

    I'm sorry, but this idea (aside from applications already being employed, like in radio and radar) isn't going to go much further.

    And this thread gets a short leash. You're new, so I'll give you the benefit of the doubt, but we don't argue conspiracy theory here.
     
    Last edited: May 29, 2006
  9. Gokul43201

    Gokul43201 11,141
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    I don't know about the technical difficulties involved but if you do transmit in the very far radio-wave (~1 kHz) range, the absorption coefficient of human tissue goes down by at least 5 orders of magnitude compared with microwaves.
     
  10. Please give me an example of something that is charged wirelessly. The only thing I know of that comes close is my electric toothbrush which is the secondary winding of a transformer. It still has to sit in the base, but there are no contacts.
     
  11. dav2008

    dav2008 624
    Gold Member

    I think he was saying that if wireless electricity was made available then those are the things that would be made more convenient.
     
  12. russ_watters

    Staff: Mentor

    True, but if you do that, you start to get wavelength issues - it wouldn't be practical to connect the Arecibo radio telescope to your laptop to gather the energy.
    Ksree said "can be," not "is".
     
  13. Gokul43201

    Gokul43201 11,141
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    But it would be cool !! :approve:
     
  14. Yes that's true. But in this discussion I'd say my point stands. I've got plans for a perpetual motion machine that 'can be' built too.
     
  15. Please give me an example of something that is charged wirelessly. The only thing I k

    As per my knowledge, Crystal Radio works without receiving any electricity through wires or Battery.

    Ksree
     
  16. berkeman

    Staff: Mentor

    True, but my old crystal radio could only output a hard-to-hear signal to an earphone. And the antenna needs to be about 75 meters long to pick up the 1MHz AM band here in the US. That's a mighty long antenna for not much power out.

    BTW, talking about lighting lights remotely brought back a memory from my college days. My roommate one year was a slightly crazy ChemE who worked at the college radio station in his spare time as a disk jockey. He told me a story one time about when he and a couple of buddies went up to the rooftop transmitter antenna at night, and played Star Wars light sabres with flourescent tubes. Apparently the EM field was high enough there under the antenna structure that once you got a flourescent tube fired with a ballast, you could disconnect it and walk around with it glowing in your hands. Pretty cool. It was an FM station (KDVS in Davis, CA), so the frequency was probably in the 80MHz range. Even though the body absorbs less RF there compared to 2.4GHz microwaves, I still don't think I'd like my house to have that kind of power zinging around everywhere....:yuck:
     
  17. Please give me an example of something that is charged wirelessly. The only thing I k

    Recently I come across one more process or instrument that receives energy from RF waves. That is passive RFID tag. As per our RFID consultant "The scanning antenna puts out radio-frequency signals in a relatively short range. The RF radiation does two things; it provides a means of communicating with the transponder tag (the RFID chip) AND (in the case of passive RFID tags) it provides the RFID device with the energy to communicate. This is an absolutely key part of the technology; RFID devices do not need to contain batteries, and can therefore remain usable for very long periods of time (maybe decades)"
    We are using RFID process to read lot of data about thousands materials on truck without unloading the truck or opening packages. After issuing goods to operations, periodically RFID tracks where they located, status and some other data.

    Ksree
     
  18. Dallas Semiconductors makes chips like that. However, the power levels are still way off compared to charging a laptop battery wirelessly.
     
  19. I realize it has been about 3 years since the last post. I just wanted to say that I have conducted a few wireless experiments myself. It is very easy, just hook up a coil of wire to an ac source and then take an led and hook it up to another coil. Bring the coils together and the led will lite up. Florecent light bulbs that Tesla used worked on the same principle. The problem with wireless transmission is that voltage is easy to transfer, but current is next to impossible. This is why florecents could lite up from far away, but it would be very difficult to charge a laptop battery. And despite the fact that Tesla claimed only 5% is lost in transmission, which is probably true, the power required to actually transmit it is enormous compared to what you can extract on the other end, making it very costly.

    The bottom line is, yes we could do it, but it would cost too much. Kind of like solar power. Solar power would be great, but you would be paying about 30 dollars a kwhr as opposed to 20 cents a kwhr.
     

  20. How can this make any sense?
     
  21. Since we are on the topic of wireless power, this Intel research may be interesting. They released some of their experiments regarding wireless power transmission for the home. Things like powering lights and laptops..without harming humans.

    "The trick with wireless power is not can you do it; it's can you do it safely and efficiently," Intel researcher Josh Smith said in an online video explaining the breakthrough

    http://afp.google.com/article/ALeqM5jn6duu12s7ujb6ByZ1wuv389gooQ
     
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