You’re on your way home. It’s a long walk, but at least you have your cellphone so you can listen to music. Oh wait, it’s out of battery! Wouldn’t it be great if your cellphone, and other devices for that matter, could recharge itself while walking? Enter energy harvesting. With energy harvesting, you have a lot of small systems that can harvest for example solar or thermal energy, essentially taking advantage of otherwise wasted energy. With nanotechnology, such systems can be developed to be so small and flexible so that it can be embedded in clothing, and with piezoelectric nanocrystals, you could even harvest energy from the movement in your clothes. So in reality you are a walking power source for your mobile devices.