From my understanding when a magnetic field passes through a coil it generates a current. What prevents us from being able to create a coil that can harness earths magnetic field to generate a current/electricity? Would it need to be huge? Is the earths magnetic field to low? Idk I’ve been thinking about it a lot recently and I just don’t understand why it wouldn’t work.
In: Planetary Science
Well, the Earth’s magnetic field is like that one friend who’s always a bit unreliable – strong but inconsistent. Trying to harness it for energy is like asking that friend to power your entire house: sounds fun in theory, but it’s a bit too much to ask for right now.
You need to have the earth spin and the coil be stationary, also the magnetic field of the earth is too weak, and would require very fast rotation speeds
It has to be a movingchanging magnetic field to make current in a coil. Eg if you hold a magnet beside a wire loop nothing happens. If you *spin* a magnet inside a wire loop it makes electric current in the wire.
Having a coil on the Earths surface doesn’t make electricity because the field and the coil are both stationary relative to each other. It’s like just holding a magnet and wire beside each other. You’d need a coil outside of the planet while the Earth spins beside or inside of it to generate electricity.
because it doesnt move relative to us (well, not enough at any rates).
Magnets dont make electricity. MOVING magnets make electricity.
Now, this all changes for an object in orbit, for an object in orbit it IS possible to harvest some energy, but thats for orbital objects, so not generally relevant. https://pwg.gsfc.nasa.gov/Education/wtether.html
The coil would have to move relative to the magnetic field, just like it does in real electric generators.
Besides, the Earth’s magnetic field isn’t anywhere near as strong in any one place as the magnets in generators, and the magnets don’t produce the energy – the energy comes from whatever’s spinning the coil.
You can, NASA has done a few experiments with what is known as an electrodynamic tether.
They can be used to generate electricity by extending a long conductive tether in orbit, the orbit lowers as the power is extracted.
They can also be used to raise a satellite’s orbit by feeding in power.
https://en.wikipedia.org/wiki/Electrodynamic_tether
Static Magnetic fields itself don’t create energy. You need changing magnetic fields. The natural changes in earth magnet field are very tiny and slow and you can not draw any meaningful amount of energy from it.
Just putting solar cells on the ground produces much more electricity and is much easier, than anything we could do with the earth magnetic field.
Like you said, it’s when a magnetic field PASSES through a coil. We could make such a coil but if we just let it be, it would be stationary so it wouldn’t create any electricity. We would need to move it and for that we would spend more energy than the crested electricity
The key part you’re missing is electricity would only be generated when a changing magnetic field passes through a coil
Earth Batteries might fit the bill. Stick some poles in the ground in the right orientation and harness the Earth’s electric currents. Also seemingly works at sea.
https://en.wikipedia.org/wiki/Earth_battery
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