This seems to imply that you just replace all fossil fuel energy sources with batteries which does not even make sense. Once the batteries have been discharged, how would you recharge them?
What should actually be done is scale up renewable power generation and then you’d use the batteries to balance out the difference between production and consumption, which takes a lot less batteries than trying to replace energy generation with energy storage (which, again, would not even work).



In theory, as long as there is nothing ferromagnetic inside what you put into the center of the coil, there shouldn’t be anything happening at all, harmful or otherwise.
That being said, please don’t stick bodyparts inside workshop tools.