Portable devices could be hydrogen powered if fuel cell technology could be made smaller -- a design 3 mm across might do the trick...

In the 21st century, issues surrounding resource consumption, global warming and overpopulation are surfacing more frequently. Progressive corporations, businesses and individuals are working toward being more independent of depletable resources, and improving their ability to self-sustain.

Mining for helium-3 on the moon is being considered as another alternate fuel source.