Do you know how an automatic watch can reserve power from kinetic energy and convert that to electric energy? Well, there's a new smartphone that uses kinetic energy to operate. No batteries required! As long as you're swinging your phone around, you can talk, text, and browse as long as you'd like!
Actually, I'm sure we'll see something like this in the near future. We're seeing batteries that have built-in solar panels. It's only a matter of time before kinetic energy can be repurposed in smartphones as electrical power.