• If you do the arithmetic (a wifi transmitter is limited to 4W output, and the surface of a sphere is 4πr^2), it’s apparent that you’ll get a noticeable amount of charging only if you put the gadget next to the transmitter (at the very least, closer than a meter).

    At how many public hotspots do you even know the location of the transmitter, let alone have close physical access to it? Cute idea, but I don’t see much of a future for it.