# Can Earth's Magnetic Field Create Electricity?

If the earth has a magnetic field, can it, in theory, be run through a conductive metal coil to create electricity?

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Not really. A magnetic field alone doesn't create electricity. A changing magnetic field does. The Earth's magnetic field does change a tiny bit but not enough to really generate much.

The other option is to move the inductor in the magnetic field. The Earth's magnetic field is quite homogeneous over short distances though so the coil would need to move fast and very far to generate much. This would use more energy than it creates (at least on the surface of the Earth).

Several years back there was an experiment (the Space Tether Experiment) to drag a conductor through the Earth's magnetic field with the Space Shuttle. I don't know how viable this is though because I think it saps orbital energy.

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"The Earth's magnetic field is quite homogeneous over short distances though so the coil would need to move fast and very far to generate much." You can just spin a coil. The issues are that: (1) the earth's field is weak, and it's easier to use the field of a stronger permanent magnet; and (2) as with any generator, it requires an input of energy to turn the crank. –  Ben Crowell May 19 at 3:45
@BenCrowell I think we're in agreement. I was not imagining the coil spinning. I was imagining it on a train or something like that. But my point was that you'd have to make it move really fast and really far to generate anything useful and the energy needed to move it would use far more than in generated. –  Brandon Enright May 19 at 3:46
If you put in energy into the coil, there seems to me no reason that you couldn't then get momentum out of it. I don't know how viable this would be in practice, but in theory it seems like you could use a coil to push against the Earth and slowly raise or maintain your orbit. –  AlanSE May 19 at 3:49
The efficiency would depend on the quality of the bearing. There is no fundamental reason that it has to be inefficient. The coil doesn't have to move far or fast. If it has some large number of loops, you can generate a large emf by spinning it slowly. –  Ben Crowell May 19 at 3:58
@AlanSE also as far as efficiency goes for keeping the orbit one should do the energy balance between small rockets/jets and spending it in rotating a gismo. –  anna v May 19 at 4:28