We've had this technology for decades, Disney even had something planned around it so you could sit around and have your phone magically charge, for Disney specifically the problem was that it would build up dangerous amounts of electricity making normal objects deadly but more broadly the problem is that it is ungodly inefficient, like I'm talking exponentially inefficient, electricity follows the square cubed law, meaning for every one unit you move away from the source you loose 3/4 of your original energy.