Alternatives to petroleum-derived transportation fuels can be produced from oil shale, coal, and from a variety of carbonaceous materials including both cultivated biomass and waste materials. In the long-term, hydrogen, often mentioned as an alternative fuel, may be used as an energy carrier or transfer agent; it should not, however, be considered as an energy resource. Among the alternatives, coal-derived or shale-derived fuels could become significant in the national supply within the century. The other alternatives are long-term (post-2000), or, at least without extensive resource development, they are resource-limited.
Any identifiable shale-derived fuel probably will appear as conventional finished fuel--either gasoline or distillate. More likely, however, the shale-derived component of fuels will not be identifiable because any shale oil available for the manufacture of transportation fuels within the foreseeable future will be blended with natural crude and used as refinery feedstock.
Coal-derived fuels may be methanol, gasoline from methanol, or conventional gasolines or distillate-type fuels either synthesized from coal or refined from coal syncrude, i.e., a “liquefied” coal. Methanol or a methanol derivative would be produced using coal gasification as the primary conversion process. The technology for coal gasification is well established whereas that for coal liquefaction is not fully developed. For this reason methanol or methanol-derived gasoline are the alternative fuels most likely of production if non-petroleum fuels were to be required in the immediate future. The next most likely would be conventional fuels from coal synthesis by the SASOL process. The evidence available to date indicates that should gasoline or distillate be made from either coal or shale oil those fuels will not differ markedly from traditional fuels.