This site provides free HHO Generator Plans & Schematics. Changing water into useable energy and even fire to replace fuel or in case of a catastrophic event. For preppers this is something you need to look into. Here are some schematics I found on the web.
#328. A Crude Awakening: The Oil Crash, September, 2014. Crude oil depletion from the Earth, nears an era when consumption threatens to exceed supply. Speculating this theory, if western society fails to reinvent itself altogether, economic cataclysm is not simply likely but inevitable. (Click OILCRASH link on page)