A.CNG is made by compressing natural gas, (which is mainly composed of methane, CH4), to less than 1 percent of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 20–25 MPa (2,900–3,600 psi), usually in cylindrical or spherical shapes.
A.CNG is used in traditional gasoline/internal combustion engine automobiles that have been modified or in vehicles which were manufactured for A.CNG use, either alone ('dedicated'), with a segregated gasoline system to extend range (dual fuel) or in conjunction with another fuel such as diesel (bi-fuel). Natural gas vehicles are increasingly used
Natural gas vehicle have lower maintenance costs than other hydrocarbon-fuel-powered vehicles.
A.CNG fuel systems are sealed, preventing fuel losses from spills or evaporation.
Increased life of lubricating oils, as A.CNG does not contaminate and dilute the crankcase oil.
Being a gaseous fuel, A.CNG mixes easily and evenly in air.
A.CNG is less likely to ignite on hot surfaces, since it has a high auto-ignition temperature (540 °C), and a narrow range (5–15 percent) of flammability.
A.CNG-powered vehicles are considered to be safer than gasoline-powered vehicles.
Less pollution and more efficiency:
o A.CNG emits significantly less pollution directly than gasoline or oil when combusted (e.g., carbon dioxide (CO2), unburned hydrocarbons (UHC), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx) and PM (particulate matter)). For example, an engine running on petrol for 100 km emits 22 kilograms of CO2, while covering the same distance on A.CNG emits only 16.3 kilograms of CO2.
o Due to lower carbon dioxide emissions, switching to A.CNG can help mitigate greenhouse gas emissions. However, natural gas leaks (both in the direct use and in the production and delivery of the fuel) represent an increase in greenhouse gas emissions. The ability of A.CNG to reduce greenhouse gas emissions over the entire fuel lifecycle will depend on the source of the natural gas and the fuel it is replacing.