Why can't we make electricity from the earth's magnetic field? It should be possible according to the law of electromagnetic induction(unless I am wrong).
Answers
Answer:
You're absolutely right we can make electricity from continuous variation of parameters like Area and angles to change the magnetic flux through a loop and produce current.
However, the difficulty is that the magnitude of Earth's magnetic field is very low locally at any point.
Hence, because the induced emf is directly proportional to the magnitude of field, it's not commercially practical to produce large electricity for our uses and the bigger difficulty is that we'll have to use other machines and tools which will consume more energy than what we get back for use which is to mechanically change the angles and Area between the Direction of Coils and Fields.
For electromotive force to be induced the requirement is that there has to continuous mechanical variation in the area of the coil and angles between field and area vectors and also that magnitude and direction of Earth's magnetic fields can't be controlled by us.
Hope this helps you and was convincing enough to you !