Today the world is facing three critical problems: (1) high fuel prices, (2) climatic changes, and (3) air pollution. Experts suggest that current oil and gas reserves would suffice to last only a few more decades. Biorenewable liquids are the main substitutes to petroleum-based gasoline and diesel fuel. These fuels are important because they replace petroleum fuels; however, some still include a small amount of petroleum in the mixture. There are four alternate fuels that can be relatively easily used in conventional diesel engines: vegetable oil, biodiesel, Fischer-Tropsch liquids, and dimethyl ether. The main alternate fuels include (m)ethanol, liquefied petroleum gas, compressed natural gas, hydrogen, and electricity for operating gasoline-type vehicles. Bioethanol is an alternate fuel that is produced almost entirely from food crops. The primary feedstock of this fuel is corn. Biohydrogen is an environmentally friendly alternative automotive fuel that can be used in an internal combustion engine.