Nope, I don’t mean the ones Nokia is purportedly developing that converts ambient radio waves into electrical energy (basically a solar cell for wider range of frequencies). That’s a terrible idea. I mean something even simpler.
Have you ever owned a shock-powered watch? In the span of a day, there’s enough physical shock to power a watch for a lifetime. But watches are boring. Instead, why not use that otherwise-wasted energy to power a cell phone? Inserting a miniature coil into a cell phone is easy (and not costly). Every step you walk should be enough for another minute of talking. Even if you were to go on a bumpy bus ride for 10 minutes, you should have enough power for a few days of standby or a couple hours of talking. And if you’re inserting this into a smartphone, you get an accelerometer by default!
So for the price of a charger (which must necessarily come with a transformer), you get (1) everlasting power (as long as you’re not a sedentary sloth like some of us are) and (2) an accelerometer.
I wonder why nobody has thought of this idea before. Will someone give me a patent, please, for suggesting something that will eliminate the need to plug in the phone?
(In case you don’t believe me, there are shake-powered flashlights: http://www.woot.com/Blog/ViewEntry.aspx?Id=8531)