Compressed Natural Gas (CNG): Components, Applications, Advantages & Limitations

Q: What is the full form of CNG?

CNG's full form is Compressed Natural Gas. The methane gas is primarily compressed for its use as a fuel in CNG.

Q: What is the full form of LPG?

LPG full form is Liquefied Petroleum Gas. It is a mix of propane and butane which is stored as a liquid.

Updated on September 10, 2026Author:NEXT IAS Contributors

The full form of CNG is Compressed Natural Gas (संपीड़ित प्राकृतिक गैस). CNG is clear, odorless methane gas compressed to under 1% of its volume. CNG has a high auto-ignition temperature of about 540°C compared to other fuels such as petrol and diesel. This is the reason which makes it less prone to catching accidental fires. It has a narrow flammability range of about 5 to 15% in air. CNG is lighter than air which improves the safety as any leakage disperse quickly in the surrounding environment. CNG vehicles first appeared in Italy in the 1930s. Presently, many countries such as Iran, India and China operate the world's largest CNG fleets with millions of CNG vehicles globally.

Main Components

S.No.	Component	Chemical Formula	Volume in CNG	Role
1	Methane	CH₄	85 to 95%	It is the primary combustible component in CNG. It provides clean burning and high calorific value.
2	Ethane	C₂H₆	2 to 10%	It adds to energy content and burns cleanly.
3	Propane	C₃H₈	0 to 5%	It enhances combustion efficiency.
4	Butane & higher hydrocarbons	C₄H₁₀	Trace to about 2%	They have small energy contributions.
5	Carbon dioxide	CO₂	0 to 2%	It is Non-combustible gas and reduces the high calorific value.
6	Nitrogen	N₂	0 to 2%	It acts as an inert diluent. It lowers the heating value if present in large amounts.
7	Others (H₂S, water vapour, traces)	--	Trace	They are removed during processing to avoid corrosion and emissions.

Applications of CNG

The Compressed Natural Gas (CNG) is widely used as an alternative transport fuel for vehicles such as cars, buses, trucks, auto-rickshaws, two wheelers and also used in some trains.
The CNG is primarily used in urban regions for a cleaner environment and less air pollution. The cities such as Delhi, Mumbai and many Latin American cities run large CNG bus fleets to cut down the particulate matter and NOₓ emissions.
In industry, CNG is used as a fuel for boilers, furnaces and kilns. It also processes heaters in the sectors like textiles, ceramics, food processing and metal works. In such industries, the CNG replaces diesel or coal which ultimately help in reducing the pollution of nearby regions.
It is also used for power generation in small gas-based power plants, power units and backup generators where the pipeline gas is unavailable but CNG can be used.
In case of domestic and commercial use, CNG or other piped natural gas can help in cooking and water heating. The clean combustion is suitable for densely populated regions and indoor applications with appropriate safety measures.

Comparison of CNG and LNG

S.No.	Feature	CNG (Compressed Natural Gas)	LNG (Liquefied Natural Gas)
1	Physical state	CNG is compressed gas at ambient temperature.	LNG is Liquid at cryogenic temperature of about -160°C.
2	Storage pressure	It has a high storage pressure of about 200 to 250 bar.	It has low storage pressure of slightly above 1 bar in insulated tanks.
3	Storage temperature	CNG requires Ambient temperature which means no cooling needed.	LNG requires a very low cryogenic temperature.
4	Energy density (volumetric)	It has lower energy density. It requires more volume needed for the same energy.	It has a much higher energy density of about 2.5 times more than CNG, closer to diesel or gasoline.
5	Typical vehicle range	CNG is suitable for a shorter range. It is suited for city buses, taxis, and short-haul trucks.	LNG requires a longer range. It is suited for heavy-duty trucks, ships and long-haul transport.
6	Infrastructure	It comprises high-pressure compressors, CNG dispensers and cylinder cascades.	It includes liquefaction plants, cryogenic tanks, LNG dispensers, and regasification.
7	Safety Parameter	CNG is lighter than air. It disperses quickly in case of leakage.	LNG is heavier when cold. It requires strict cryogenic handling and insulation.

Advantages of Compressed Natural Gas

The Compressed Natural Gas (CNG) burns cleaner than other fuels such as petrol, diesel or coal. It produces very low particulate matter, sulfur oxides and nitrogen oxides and about 20 to 30% less carbon dioxide per unit of energy. It improves the urban air quality and reduces the greenhouse gas (GHGs) emissions.
CNG is usually cheaper than gasoline and diesel in most of the countries which lowers the fuel cost for transport operators and households and reduces dependence on imported crude oil.
The CNG based vehicle engines have longer oil life and less engine wear due to cleaner combustion. It is safer fuel as it is lighter than air and disperses rapidly in case of leakages. It reduces explosion risk compared to other liquid fuels.
CNG tanks are strong and deploy high pressure cylinders designed at par with complete safety standards. CNG has a higher auto-ignition temperature than petrol.
It supports energy diversification and allows countries with domestic gas resources so that it can be used in transport and industry. It also improves the energy security and creation of jobs in the gas sector and vehicle conversion.

Limitations

The Compressed Natural Gas (CNG) has a lower energy density by volume than liquid fuels. Thus, the vehicles require heavy high-pressure cylinders and reduce passenger space. It further increases the overall weight of the vehicle which can affect the vehicle performance.
The driving range of CNG based vehicles are comparatively shorter than other fuels such as petrol, diesel and LNG vehicles. It further makes them less suitable for travel in remote areas.
The CNG infrastructure is capital intensive and requires high pressure compressors, cascade storage and a dense network of refueling stations.
The factory built CNG vehicles or the conversion of the vehicles in CNG are costlier. Also, the maintenance requires trained technicians.
In many regions, the gas quality, supply disruptions or policy changes can affect the reliability of the industries which are dependent on CNG.