Nano-generated electricity and/or a newer form of energy evolved from bio-nano technology, though more lasting and easier to generate.
Example: Recently nano-generated power has been evolved in the form of nano-strands (thinner than a human hair) which generate power via the friction of being rubbed together. In clothing uses this reaction can generate enough power to operate night-vision goggles for soldiers or the like. The only hold back is this type of clothing can not be laundered/cleaned in a conventional manner. A next step would be use the same technology to provide automatic expulsion of dirt and debris from said clothing providing on going cleanliness.