CNG

• Compressed natural gas (CNG) is a fossil fuel substitute for gasoline (petrol), diesel, or propane/LPG.
• 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 (natural gas is lighter than air, and disperses quickly when released).
• CNG may also be mixed with biogas, produced from landfills or wastewater, which doesn't increase the concentration of carbon in the atmosphere.

CNG is made by compressing natural gas (which is mainly composed of methane [CH₄]), to less than 1% of the volume it occupies at standard atmospheric pressure.

 It is stored and distributed in hard containers at a pressure of 200–248 bar (2900–3600 psi),
usually
CNG's volumetric energy density is estimated to be 42% of liquefied natural gas's (because it is not liquefied), and 25% of diesel's.^[4]