So IFLS has written two articles on a couple possibilities on where energy generation could come from in the future:
Micro-turbines could revolutionize small-scale energy production
Charge Gadgets Just By Walking

First on the list: mini turbines! Apparently people thing wind turbines are ugly, so some scientist went and made them so tiny you can’t really see them; ten can fit on a grain of rice. Apparently they’re sturdy despite their size, and could viably produce energy–a hundred or so to charge a cell-phone. If the scientists can get them mass produced, they’ll be cost-effective, too. There’s also talk of other micro-robot type stuff, so of course this too will lead to the robot apocalypse. Read the article for more details.

Second: People move around anyways, so why not let all that “wasted” energy go to charging your gadgets instead? Apparently this nifty invention will work like a hand-crank flashlight. You just stick the special liner in your shoe, plug in your device, and go for a walk. It’s a practical little invention for those of us constantly letting our cell phones die…