Using the Earth’s Magnetic Field To Generate Electricity?
Here’s a post intended for physicists like Glenn Doty to comment upon. A reader asks: Say we make a circumnavigating coil of conductor material, wouldn’t you generate a current? I am not into big money investments in risky ventures, but this might turn into something.
I would say:
- The Earth’s magnetic field is very weak compared to that found in generators.
- You would be proposing a huge conductive ring mounted on the Earth? That doesn’t sound feasible.
- Every kWh of electricity generated would subtract from the Earth’s kinetic energy of rotation, though I suppose those effects would be infinitesimal.
Did I get any of this right? Thanks.
That would be about as practical as erecting huge electrodes to capture electricity from the northern lights.
I’m sure it’s impractical, but I’d like to know exactly why.
The current in the northern lights is very diffuse so a huge area would be needed to collect adequate current. The height of the electrodes would have to be so great that supporting them would be impractical. Also, the power collected would be intermittent, i.e. there would be none available for months at a time.
I suppose that it would be an interesting experiment to fly two kites with conducting tethers some distance apart. Then, by connecting instruments between the two tethers, one could determine how much power would be available.
I certainly support your broad-strokes criticism.
🙂
At a guess – and this is only a guess since I don’t have time to grind through the numbers right now – I’d suspect that the energy derived from such a system might have a LCOE of ~$5,000,000/MWh, but it could easily be higher still.
The only thing you left out was the maintenance costs. You’re talking about a giant ring in space, traveling in an endless circle at >17,000 mph… The inevitable maintenance issues that come up (say a solar flare causes a section of the wire to heat up to above superconducting temperatures, and now you have a few hundred miles of burnt-up wire that have to be replaced/re-threaded, or a boost thruster goes down and needs servicing).
It’s an interesting thought experiment, but this is about as impractical as it gets. If you’re going to spend that much money creating the ring, you might as well put up large solar collectors. THAT nonsense idea would only be in the ~$100,000/MWh range.
😉
Thanks very much, Glenn.
A related field of curiousity is the “Earth Battery” that use telluric currents to induce a current in a buried wire. This power source was reported to be used to power old telegraph systems. https://en.wikipedia.org/wiki/Telluric_current