Obtaining Electricity from the Earth's Magnetic Field

[AliAhmed]

If we would build a copper ring that would orbit around the Earth (like a big belt), could we generate electricity from it (because of the Earth's magnetic field). I know it's impractical, but I'm curious as to how much electricity we could get.

 

[Redbelly98]

No, I don't think this would work. Yes, the rotating Earth would induce a current in a stationary ring, but the interaction between the current and Earth's field would produce a torque on the ring causing it to rotate in the same direction as Earth's rotation. Eventually the ring would simply rotate along with the Earth, and there would no longer be a change in magnetic flux through the ring. No flux change, no induced EMF or current.

 

[AliAhmed]

Thanks for that. Though it's a little disappointing, it's nice to here why it won't work.

 

[LURCH]

A charge is induced when a conductor moves back and forth from the negative to the positive poles of a magneic field. So, a ring in an eqatorial orbit would not work. But a conductor in a polar orbit would induce some charge.

NASA tried this with the Shuttle once. One of the practicle problems was that the shuttle only completes one orbit every 90 minutes or so, which means that it moves from its most northerly position to its most southerly in about 45 minutes. This slow oscillation generates very little charge. The solution: a very long conductor. They spooled out a wire about 12 miles long.

This was in the late 1990's and, as I recall, when the wire was fully spooled out...it just kept going. Darn thing broke right off at the base with barely a pause!