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Question on remote power harnessing?

  1. Jun 27, 2009 #1
    This might sound like a question on pseudo-science but has there been any study done on the possibility of harnessing energy from a wireless remote power source? In other words, a machine drawing power from a generator without means of wires, pipes…ect. Of course, solar power comes to mind but this is not quite what I mean. What I mean is, a generator emits energy and a machine harnesses and is powered by means of simply being within a certain radius of the generator. Is this something that is physically possible in theory or is this simply science fiction?
  2. jcsd
  3. Jun 27, 2009 #2


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    Staff: Mentor

    It is possible and it is done, but not exactly in the way that you envision. Radio stations do this, and they are the closest to what you describe. Electric toothbrushes do it too, but at a range of a few milimeters. But transmitting power omnidirectionally is extremely inefficient, so the idea doesn't hold a lot of promise for the application you describe.
  4. Jun 27, 2009 #3


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    Staff Emeritus
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    How do you think a radio works? It draws a very small amount of energy from the field radiated by a radio station. The difficulty is that the radio station radiates Megawatts and your radio receives milliwatts. This same principle applies in general to all radiated power. It can be done but only with large losses.

    You can beam energy will lower losses but there then the receiver and transmitter must be in line of sight and maintain a fixed relationship, ie the transmitter and receiver must be pointing at each other. Then, if the energy density is high, you must be careful not to interupt the beam with living creatures.
  5. Jun 27, 2009 #4


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    Induction is an example of wireless power transfer. The primary/secondary windings are example s of this. This can be used for near field power transfer. See this homemade circuit.

    Using lasers is also an interesting thought. But one has to question the efficiency when using this method. This requires a direct line of sight with the source of the laser and the solar cell receiver. May be somewhat useful for low power devices.

    But the key here is efficiency
  6. Jun 27, 2009 #5


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  7. Jun 27, 2009 #6
    The wireless transmission of energy is certainly not new, but has significant concerns.
    Omnidirectional transmission is the most "accessible" but also the most wasteful.
    Unidirectional transmission is the opposite.
  8. Jun 27, 2009 #7


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    I think to answer the meat of this question, it should be stated that we do know how to transmit power wirelessly purely for the sake of transfering power (as opposed to the fact that radios incidentally transmit power but it's purpose is to transmit music/news). We could, for example, transmit power from solar arrays in Earth's orbit down to receivers on the ground.... except why should we? Transmitting electricity wirelessly is inefficient and there are plenty of practical inconveniences. The real problem is that it's a solution where there is rarely a problem! We transmit electricity over electrical lines from say, a solar panel field at what... 95% efficiency at a very very low price! FAR lower then putting a satellite in orbit with panels just to get that bit more power/area.

    Short answer, yes, easily doable. The problem is there's no reason to. Infact, we had an article in a thread up a few weeks ago where Nokia thinks there's enough energy flying around us from radio stations and what not that they can harness it to charge cell phones wirelessly!
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