A Natural gas vehicle or NGV is a vehicle that uses compressed natural gas (CNG) or, less commonly, liquified natural gas (LNG)) as a clean alternative to other automobile fuels. Worldwide, there are roughly 4 million NGVs as of 2004, with the largest number of NGVs in Argentina, Brazil, and Pakistan.
While existing gasoline-powered vehicles may be converted to CNG, an increasing number of vehicles worldwide are being manufactured to run on CNG.
Natural gas
Chemical composition and energy content
Chemical composition
The primary component of natural gas is methane (CH4), the shortest and lightest hydrocarbon molecule. It may also contain heavier gaseous hydrocarbons such as ethane (C2H6), propane (C3H8) and butane (C4H10), as well as other gases, in varying amounts. Hydrogen sulfide (H2S) is a common contaminant, which must be removed prior to most uses.
Energy content
Combustion of one hundred cubic feet (1 ccf) of commercial quality natural gas typically yields approximately 1 therm (100,000 british thermal units, 30 kWh). One cubic meter yields 38 MJ (10.6 kWh). Natural gas has the highest energy/carbon ratio of any fossil fuel, and thus produces less carbon dioxide per unit of energy.
Storage and transport
Transport
The major difficulty in the use of natural gas is transportation. Natural gas pipelines are economical, but are impractical across oceans. Liquefied natural gas (LNG) tankers are also used, but have higher cost and safety problems.
Storage
Natural gas is often stored as CNG, in hard containers at high pressure.
External links
North America
South Asia
