The emerging field of “energy scavenging” is drawing on a wide array of untapped energy sources — including radio waves, vibrations created by moving objects, and waste heat from computers or car exhaust systems — to generate electricity and boost efficiency. Computers feasting on their own exhaust heat. Super-efficient solar panels snaring lost thermal energy and recycling it into electricity. Personal electronics powered by stray microwaves or vibration-capturing clothing. Cellphones charged with a user’s footsteps. These and more innovations may be possible with free, green energy that is now going to waste. Ubiquitous sources like radio waves, vibration and pressure created by moving objects, heat radiating from machines and even our bodies — all have the potential to produce usable electric power. Until recently, ambient energy was largely squandered because of a lack of ways to efficiently exploit it. Now, advances in materials and engineering are […]