For years now, engineers have been working to integrate piezoelectric components into clothing. Piezoelectricity is electricity generated by mechanical stress -- in other words, bending. The minute piezoelectric parts that make this kind of energy are also sometimes called nanogenerators.
When tiny piezoelectric components bend, they generate a detectable electrical charge. Imbed these components into clothing, run several dozen miles, and you could help solve the energy crisis, right?
That idea isn't quite as far-fetched as it seems. Dance clubs have installed floors with piezoelectric parts, which bend when people dance on them. That energy is then used to power other areas of the club, such as lights or the sound system. Furthermore, a company could place the same kinds of components into, say, a soldier's boots. Each step would literally provide power to an array of battlefield devices.
One catch is that piezoelectric materials don't generally product a strong electrical discharge. Often that energy is measured in only millivolts or nanoamps. But with better ways to harvest and store the energy on a person, it could be captured, saved and funneled towards power-hungry gear in the near future.
For a soldier or adventurer stranded for days without access to electrical outlets, this kind of technology holds great potential. Suddenly, there would be a way to revive depleted batteries in a satellite phone or GPS unit. A situation that was once potentially deadly could be managed much more easily just by simply walking around for a while.
Energy-capturing clothing is still in prototype stage. Barring sudden breakthroughs in research and manufacturing, it may be years before consumer-grade shirts and shoes can turn our elbow grease into measureable electrical pulses.