The sugar can come from virtually any source, including fruits andgrains, although fuel-grade ethanol would probably come mostlyfrom corn.` Car engines can burn pure alcohol or gasohol, an alcohol–gasolinemixture (10% ethanol in gasoline), with little modification. Gasoholis now widely available in the United States.` Another potential source of liquid fuel is oil squeezed from seeds(seed oil). For example, use sunflower oil to replace diesel fuel. Oilseeds, found in a wide variety of plants, can be processed toproduce a “biodiesel” oil composed mainly of carbon andhydrogen, which of course reacts with oxygen to produce carbondioxide, water, and heat.Other Energy Alternatives` Colorado, contain huge deposits of oil shale (油母頁岩), which consists of acomplex carbon-based material called kerogen (油母質) contained inporous rock formations. These deposits have the potential of being alarger energy source.` The main problem with oil shale is that the trapped fuel is not fluid andcannot be pumped. For recovery of the fuel, the rock must be heated toa temperature of 250 C or higher to decompose the kerogen to smallermolecules that produce gaseous and liquid productsmolecules that produce gaseous and liquid products.` Ethanol (C2H5OH) is another fuel with the potential to supplement, ifnot replace, gasoline. The most common method of producing ethanol isfermentation, a pro