Sarah Kessler:

After an early wave of enthusiasm for bulky backpacks with solar-powered chargers, the new bet is on kinetic energy, or energy that can be generated from movement, including the stride of a walker or the turn of a bicycle wheel. The beauty of kinetic energy is that the more something weighs and the faster it moves, the more energy it can generate.

25 minutes walking to charge and iPhone = sign me up.

Posted by Ben Brooks