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In the past I've been shown Internet sources claiming a specific generator that uses nothing but the earth's magnetic field to generate power, I'm looking for the name of the generator?

I realize other discussions on this site have claimed (using math etc) that the energy is so minimal it isn't worth the effort, but that's not my question.

I've seen the evidence for the device on the Internet in the past, and I wish to examine the evidence of the device in detail again, yes it's not possible I'm sure by showing me all the equations, but if there are practical implementations of this technique I'd like to take a look.

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  • $\begingroup$ I very much disagree with the perpetual-motion tag, mostly because most of the energy on earth somehow eventually comes from the sun, thus the earth's magnetic field is created/sustained by the larger solar system, so just cause I'm pumping petrol into it, doesn't mean it's "not fueled" $\endgroup$
    – Ninjanoel
    Oct 21, 2013 at 12:12
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    $\begingroup$ @Ninka Noel Actually I think that that energy does not come from the sun, but from the radioactive isotopes decaying in the earth core, thus keeping its temperature high, which generates convection of the iron core, which in turn generates the magnetic field. $\endgroup$
    – Nicolas
    Oct 21, 2013 at 12:29
  • $\begingroup$ @Nicolas lol, thanks, I also put in my original question 'p.s. i'm no physicist', so yeah, in my simplistic model, planet earth formed because the sun came about (I assume we don't find planets with magnetic fields that have formed with no connection to a solar system of some kind), but yeah, probably what you said, but anything that decays wont last forever anyway, so still not perpetual-motion. $\endgroup$
    – Ninjanoel
    Oct 21, 2013 at 13:08
  • $\begingroup$ @NinjaNoel Unless this claimed generator directly interacted with the Earth's inner dynamo in such a way as to reduce its internal energy - thus decreasing the Earth's magnetic field - then this falls in the perpetual-motion category. But if you feel strongly about it, it's OK. $\endgroup$
    – Emilio Pisanty
    Oct 21, 2013 at 14:09
  • $\begingroup$ en.wikipedia.org/wiki/Fluxgate_compass $\endgroup$
    – Optionparty
    Oct 22, 2013 at 19:17

3 Answers 3

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You can't generate power from a static magnetic field alone. In this context, the earth is just a permanent magnet, and a rather weak one at that. To generate electric power from that, you have to move electric conductors, like wires, thru the field in the right direction and with the right orientation of the conductor.

If any electric power is taken from the resulting EMF produced by the moving wire, then a force will be required to continue moving the wire. Put another way, the wire will "push back" as you try to move it thru the magnetic field. That push times the velocity represents power you have to put into the system to get the electric power out. Power isn't coming from the earth.

You can get the same effect by passing a wire thru the field created by any other permanent magnet. The reason this is usually done instead of using the earth's field is that a deliberate magnet can easily have a much stronger field, although much smaller in size. You can also get the same effect by holding the wire still and moving the magnet, which is not a option when using the earth's magnetic field. In the case of moving the magnet, it will require force to move past the wire when electric power is drawn from the wire.

There is no free lunch here, and any claims to the contrary are just bunk and a waste of time to persue.

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  • $\begingroup$ thanks for your contribution, but I'm still looking for the name of the machine in question. p.s. the earth may APPEAR to be a permanent magnet, but in fact it has constant tiny variations. I don't get the free lunch comment, the energy present in the whole of the Earth's magnetic field is enormous, what you saying is we not smart enough to harness it... thanks for you contribution. $\endgroup$
    – Ninjanoel
    Oct 21, 2013 at 13:13
  • $\begingroup$ Obviously I agree that the "free lunch" theorem holds; however understanding why they are false is most of the time very informative (think about "maxwell's demon" for example) $\endgroup$
    – Nicolas
    Oct 21, 2013 at 13:17
  • $\begingroup$ @NinjaNoel That energy is not "enormous" at all : $\frac {B^2}{2\mu_0}\simeq 10^{-3} J.m^{-3}$ $\endgroup$
    – Nicolas
    Oct 21, 2013 at 13:21
  • $\begingroup$ @Ninja: As I said, these things don't really exist, so it's hard to say what names people have attached to these mythical devices. Try "free energy", "perpetual motion", or "fraud". Yes, you could in theory extract power from the changing of earth's magnetic field, but such variations are so slow and small that it would be difficult to measure them, let alone derive any useable power from them. Yes, the total energy in earth's field is large, but it's a static field, so can't be converted to power anymore than the fixed field of a permanent magnet can. $\endgroup$
    – Olin Lathrop
    Oct 21, 2013 at 13:31
  • $\begingroup$ my favourite example for these sort of things is that the first computer hard drive was as big as a house and stupidly small in data storage space (measured in Kilobytes), now I my ipod has 60 Gigabytes of data and it fits in my pocket. Does anyone have an example of any machine that produces any amount of energy derived solely from the earths magentic field. simples. It can be done, who cares it's it's not practical, it may become practical after enough research and development, dreaming big is what the human race is all about! $\endgroup$
    – Ninjanoel
    Oct 21, 2013 at 13:39
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I don't know the name, but you can certainly do it. Just make a loop of wire and rotate it around a vertical axis. Use some brushes to allow the rotating loop to make electrical contact with your fixed circuit and take out the energy or spin the circuit with the loop. You will need some source of mechanical energy to spin the loop-that is where the electrical energy comes from. The flux you are cutting is about the half Gauss field times the area of the loop. That will allow you to calculate how much you can generate.

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  • $\begingroup$ This doesn't answer the question since it violates the OP's requirement of "uses nothing but the earth's magnetic field to generate power". As you say, you will need some source of mechanical power to spin your loop. The OP is looking for the name of something fradulent he found on the internet. Yours is a real buildable device, but doesn't produce free power. $\endgroup$
    – Olin Lathrop
    Dec 22, 2013 at 17:27
  • $\begingroup$ @OlinLathrop: good point. I am much more active on math, where we had different crank problems. $\endgroup$
    – Ross Millikan
    Dec 22, 2013 at 17:36
  • $\begingroup$ I like this answer best, but yeah, I was hoping it was possible with no mechanical motion. No other answers are coming soon I presume so I'm marking this as my accepted answer. $\endgroup$
    – Ninjanoel
    Jan 2, 2014 at 12:45
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generator that uses nothing but the earth's magnetic field to generate power Set up a coil, or even a conducting disk, and wait for the magnetosphere to billow re solar activity. You won't get much. As stated above, spinning a coil or a homopolar generator in 0.4 gauss field won't get you much either.

http://www.lhup.edu/~dsimanek/museum/unwork.htm
Perpetual motion machines.

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