Compressed Natural Gas (CNG) is a fossil fuel substitute for gasoline, diesel, or propane. Although its combustion does produce greenhouse gases, it is a more environmentally clean alternative to those fuels, and it is much safer than other fuels in the event of a spill.
CNG is made by compressing natural gas and is stored and distributed in hard containers, at a normal pressure of 200–220 bar (2900–3200 psi), usually in cylindrical or spherical shapes.
CNG is used in traditional gasoline internal combustion engine cars that have been converted into bi-fueled vehicles. Natural gas vehicles are increasingly used in Europe and South America due to rising gasoline prices.