Natural gas is an odorless, nontoxic, gaseous mixture of hydrocarbons—pre-dominantly methane (CH4). It is domestically produced and readily distributed through pipelines in the United States and in Pennsylvania. It is a gaseous fuel which means, it must be stored onboard a vehicle in either a compressed gaseous or liquefied state. Compressed natural gas (CNG) is typically stored in a tank at a pressure of 3,000 to 3,600 pounds per square inch. Liquefied natural gas (LNG) is super-cooled and stored in its liquid phase at -260°F in special insulated tanks. Natural gas is sold in units of gasoline (GGE’s) or diesel (DGE’S) gallon equivalents based on the energy content of a gallon of gasoline or diesel fuel.
To provide adequate driving range for a vehicle, CNG is stored in cylinders at a pressure of 3,000 to 3,600 pounds per square inch. A CNG-powered vehicle gets about the same fuel economy as a conventional gasoline vehicle on a gasoline gallon equivalent basis. A GGE equals about 5.66 pounds of CNG. CNG is used in light, medium and heavy-duty applications.
LNG is produced by purifying natural gas and super-cooling it to -260°F to turn it into a liquid. Because it must be kept at cold temperatures, LNG is stored in double-walled, vacuum-insulated pressure vessels. LNG is good for trucks needing a longer range because liquid is more dense than gas (CNG) and, therefore, more energy can be stored by volume in a given tank. LNG is typically used in medium and heavy-duty vehicles; a GGE equals about 1.5 gallons of LNG.