Demand for renewable energy has never been bigger, but how about regenerative energy? This is the creation of energy from a kinetic source that would otherwise go to waste. You may have seen this on a lot of modern EV's, Smart has even integrated it into a bicycle brake.
SolePower has a great take on this with their integrated insole solution that they are currently fundraising on Kickstarter. Their insole creates energy from your steps to charge a small battery that you can then use to charge a usb powered device such as your phone. Trevor Baylis the inventor of the wind up radio originally came up with a similar idea to create power from your steps with a shoe prototype but hopefully SolePower are going to bring their own solution to market. SolePower's device does deliver an adaptable product that will hopefully deliver great results.
The best part has to be that this is a removable insole that can be put in any of your shoes subject to fit. The battery then straps around your foot so it is easily accesible with no need to remove your shoes once charged and ready for use.
Check out their fundraising page on Kickstarter.