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I have currently been researching a lot lately about wireless transmission of power.

Currently the only methods I have seen that is viable is magnetic induction, and high voltage discharge (Tesla coil and Van de Graff generators).

The 2 methods above are not viable and not as efficient, and they require a lot of input voltage(especially for the Tesla coil and VdG generators).

Are there any other alternatives known? Even if it is ineffecient.

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    $\begingroup$ You forgot about the largest system we actually use: The sun and solar cells. $\endgroup$
    – Christoph
    Commented Aug 21, 2014 at 20:48
  • $\begingroup$ @Christoph We not in control of the transmitter though are we, i am talking about transmitting power to the remote locations where solar is not as viable $\endgroup$
    – user3294895
    Commented Aug 21, 2014 at 20:55
  • $\begingroup$ Is replacing the sun with an artificial light source allowed in your scenario? $\endgroup$
    – Christoph
    Commented Aug 21, 2014 at 21:00
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    $\begingroup$ Send a tanker truck full of fuel to the remote location and run a local generator. Fuel has incredibly high energy density - and no wires required. Seriously - good answers to this question require at least a few parameters: distance, amount of power, required efficiency, cost / Watt, .... $\endgroup$
    – Floris
    Commented Aug 21, 2014 at 21:54
  • $\begingroup$ The reason i ask is i wonder if i have discovered a new way to transmit electricity. My small experiment transmitted over a distance of 1cm (i know its miniscule). Without using high voltage output or magnetic inductance. I have only used a 9v battery as an input, have used no type of coils or radio, or microwave transmitters. By accident i have found that the multimeter near my experiment was going wild. I was just wondering if i discovered a new method of transmitting power. I am now working on scaling it as the input voltage is very low and some other parameters can be increased/decreased. $\endgroup$
    – user3294895
    Commented Aug 21, 2014 at 23:08

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You can build microwave antennas of any desired size and directivity. The thermodynamic efficiency of a properly designed microwave link should be around 50%, even though the cost would be horrendous. And if you really need lots of remote power, you can simply get yourself a nuclear power plant at that location. Not that I can see any use for that...

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If you want to transfer energy using the electromagnetic interaction, you really have three choices:

  1. Use a directed stream of photons: microwave, focused light, maybe laser. This is a "far field" solution, you need to efficiently couple energy into the electromagnetic field. You either need properly designed antennas, or efficient light sources, and good optics. This case, you use electromagnetic radiation as a mean to transfer energy.
  2. Use magnetic induction. This is a "near field" solution, and you don't want to efficiently couple with the electromagnetic field, because you want to avoid the energy from being radiated. Therefore you need to apply coils or at least some conductor that carries alternating current, and it must be much smaller than a proper antenna would be at that frequency. Note that the magnetic field in this case is much stronger than the electric field around the conductor. (High current, low voltage. Thick copper, silver plated stuff, superconductors ;) )
  3. Use capacitive coupling. This is also a near field solution, but in this case, you use the electric field around/inside a capacitor. This case, most energy will go into the electric field, and very little into the magnetic field. (High voltage, low current. Insulation, big sparks, corona discharges, standing hair, smell of ozone ;) )

So if you use electromagnetic radiation, you need to turn energy into photons, concentrate them, and catch them at the target location.

If you use one of the near field solutions, you want to avoid transmitting (that would be lost power and possibly interference).

The radiating solution would allow very long range transmission. With a strong laser array, you can go very far, but with probably poor efficiency.

The near field solution offers good efficiency: one extreme example is a transformer, where the energy transfer is almost perfect. But the range is necessarily small.

See the problem is with the near-field solution is that you have to pump an awfully lot of energy into a changing magnetic/electric field, while keeping it very small.

The problem with that is energy can be decoupled a lot of ways from that. If you put any metallic object / an object with high dielectric loss (for a magnetic / electric type of near field transmitter), it will easily get warm, or even melt/burn.

Just consider how a microwave oven or an inductive heater works.

So no canned solution for you :) Question is: how far you need to transmit, and how much power do you need?

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Capacitative coupling. IR LED, PV cell. All varieties of RF. Ultrasonic, piezo receiver (tuned). Ion wind. Ordinary wind, microturbine. Vibration (see piezo).

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