As the need for sustainable forms of energy becomes more urgent, tech companies are working harder to devise creative ways to incorporate efficient methods of consumption into their gadgets. One recent concept is the solar-powered backpack, which powers your portable electronics and also lets you lug them around.

The key to the success of the product is that it serves a function, while advertising the wearer's love for the environment. The solar panels on the backpack are prominently displayed, though at least somewhat subtle.

Solar power was a popular theme in the International room at this year's CES--and concepts of subtlety fluctuate a good deal from culture to culture. Take, for example, these gadget-charging devices from Chinese company Blueline. Its products don't seem to have much (if any) representation in the States, and until some fashion-plate celebrity deems it cool to risk his or her reputation and neck muscles with the baseball cap at left, it will likely stay like that for now

I should also note for the record that this picture doesn't quite give the scope of the hat. It broke while being shipped from China. The panel should actually stand up straight, for full environmental hipness.