Natural Gas is one of the cleanest burning fossil fuels which can be used in internal combustion engines. The fuel used in vehicles is the same fuel that is used to heat your house and cook your food. Methane is the most prominent hydrocarbon that makes up natural gas. Because of the simple chemical structure of methane (CH₄), nearly complete combustion is achieved. This produces significantly lower emissions of carbon dioxide (CO₂) and greenhouse gases; ozone forming emissions are also reduced by approximately 80% when compared to petroleum oil.

Natural Gas is currently in use as a vehicle fuel and is most commonly seen in commercial and government fleet vehicles, as well as public transportation. It’s most common form is as Compressed Natural Gas (CNG); in this form the fuel is clear, odorless, and non-corrosive and stored in high pressure cylindrical tanks. A home fueling option called “Phill” has recently been released to the public that allows users to refuel the vehicle using their household natural gas line. Another benefit of natural gas is storing it under pressure during fueling and its use; fugitive emissions and evaporation losses account for almost 50% of gasoline vehicles emissions. These are cut to almost zero when natural gas is used as a vehicle fuel.

The cost of natural gas is generally lower than that of petroleum oil because it is abundantly produced worldwide. Almost all of the natural gas used in the U.S.A. is produced domestically. Maintenance costs on CNG vehicles are also notably reduced because the fuel burns so clean; spark plugs last longer, and the time between oil changes can be extended.

Some of the drawbacks to CNG vehicles are increased weight from the reinforced storage tanks, and the limited amount of fuel they can hold, resulting reduced travel distance. One way around this problem is to use natural gas in a liquid form called LNG. Natural gas is liquefied by cooling it below its boiling point of -260^o F. By cooling it most of the impurities like sulfur, and CO₂ are removed. LNG takes up about 1/600^th of the space that CNG takes up resulting in much greater travel distance. Unfortunately LNG is currently only being used in heavy duty commercial vehicles, but research is underway to come up with new technologies for storing both CNG and LNG