I once heard a story (not sure if its true) that someone put large coils underneath high voltage electricity wires running through their property. They were able to generate/mine the electricity from these coils. The electricity company thought it was theft, as opposed to using a free resource as it does put some load on the network. I wonder where the line between theft and using energy from the air really is? wrapping a coil around the electricity wire on the street is probably theft, but a small coil to power a small portable IoT device... now that seems more reasonable.