Natural Gas is a domestic clean burning fuel designated as an alternative fuel under the Energy Policy ACT of 1992. It is primarily comprised of the hydrocarbon methane (CH4). Due to its high octane rating and chemical properties, natural gas is suitable for use in combustion engines and given its gaseous nature, it must be stored onboard a vehicle in either a compressed (Compressed Natural Gas, CNG) or liquefied state (Liquefied Natural Gas, LNG). While both CNG and LNG are considered alternative fuels, it is CNG that is commercially available to the public as a transportation fuel while LNG is largely used for heavy-duty vehicles. Furthermore, given the primary chemical constituent of natural gas, methane or CH4, natural gas is the main source of hydrogen used in the U.S., lending itself well to the emerging hydrogen fuel cell industry and its potentially pivotal role in American transportation.
 

 
US Department of Energy - Natural Gas Fueling Station Locations
 
Clean Energy - Fueling Station Locations
 
Natural Gas Vehicles For America Association
 
Natural Gas Vehicle Institute
 
US Department of Energy - Natural Gas
 
American Gas Association