[noobermin]

Want to take it even further? "Wireless power transfer" has existed since the sun started shining. Sit outside on a sunny day, and you'll receive power through the transferred through the vacuum of space.

I know, I know, I kid. We're talking specifically energy transfer that is readily convertible to electrical current.

[scoot]

Like a solar powered watch or calculator?

[noobermin]

Arguably, yes. Of course, the power requirement to recharge a battery for a calculator (in a decent amount of time) is a lot less than that for a modern cell phone. Same physics if your level of detail is Ohm's Law but very different in practice because we are talking about charging a phone batt in a comparable time to plugging it in.

[mitchty]

Yeah, kinetic energy recharge of a phone is a pipe dream, last time I remember figuring out how much energy you can get from that, it amounted to walking across the USA from coast to coast.

Solar is equally crappy.