CNG (Compressed Natural Gas) is an alternative fuel other than petrol or diesel. In Indonesia, we called it BBG (CNG). This fuel is considered to be ‘clean’ compared with the two oil fuels because the gas emitted are environmentally friendly. CNG is made by compressing methane (CH4) extracted from natural gas at storage pressure of 200 – 20 bars. CNG is stored and distributed in a high-pressure vessel usually cylindrical-shaped.