Natural gas is mostly made up of methane, about 95 percent of the natural gas in California. The other 5 percent is made up of various gases along with small amounts of water vapor. These other gases include butane, propane, ethane and other trace gases. Methane is a hydrocarbon, meaning its molecules are made up of hydrogen and carbon atoms. Because of its clean burning nature and the fact that it is not made from petroleum, as gasoline and diesel are, many automakers around the world are developing vehicles to run on natural gas.
Several vehicles are available today that operate on compressed natural gas.
Alcohols - ethanol and methanol . Electricity - stored in batteries . Hydrogen - a very special type of gas . Liquids made from coal - gasoline and diesel fuel that doesn't come from petroleum . Biodiesel - a lot like diesel fuel, but made from plant oil or animal fat .