Differences between CNG and LPG
Contents
CNG vs. LPG[edit]
Compressed natural gas (CNG) and liquefied petroleum gas (LPG) are both hydrocarbon gas fuels used as alternatives to gasoline and diesel.[1] CNG is primarily methane (CH4) extracted from natural gas sources.[2] LPG is a mixture of propane (C3H8) and butane (C4H10), and is a byproduct of natural gas processing and crude oil refining.[3][2] The primary differences between them relate to their composition, energy density, and storage methods.[4]
Comparison Table[edit]
| Category | CNG (Compressed Natural Gas) | LPG (Liquefied Petroleum Gas) |
|---|---|---|
| Main Components | Methane (CH4)[2] | Propane (C3H8) and Butane (C4H10)[2] |
| Storage State | Gas[5] | Liquid[5] |
| Storage Pressure | 20–25 MPa (200–250 bar) | < 2 MPa (< 20 bar) |
| Volumetric Energy Density | ~9 MJ/L | ~25 MJ/L |
| Density Relative to Air | Lighter than air (~0.55) | Heavier than air (~1.52) |
| Primary Emissions | Lower CO2 and NOx emissions compared to LPG | Higher[3] CO2 emissions than CNG, but lower than gasoline |
Storage and Infrastructure[edit]
The methods for storing CNG and LPG differ significantly due to their physical properties. CNG is stored in its gaseous state under very high pressure, typically 20–25 MPa, in strong, heavy cylindrical or spherical containers. In contrast,[5] LPG is stored as a liquid under moderate pressure, generally less than 2 MPa. This allows LPG storage containers to be lighter and more compact for an equivalent amount of energy.
The infrastructure[2] for refueling also varies. LPG refueling stations are often more widely distributed than CNG stations in many regions. The cost to convert a vehicle for LPG use can be lower than for a CNG conversion, which requires more robust, high-pressure tanks.
Environmental Impact and Safety[edit]
Both fuels are considered cleaner than traditional petroleum fuels. CNG combustion produces fewer greenhouse gases, nitrogen oxides (NOx), and particulate matter than LPG. LPG produces[3] more carbon dioxide than CNG, but still less than gasoline or diesel.
In terms of safety, a key difference is their density relative to air. CNG is lighter than air and disperses quickly upwards in the event of a leak, reducing the risk of fire. LPG is[1][3] heavier than air and can pool in low-lying areas, creating a potential ignition hazard if a leak occurs in a poorly ventilated space. Both fuels[1][3] are odorized to allow for the detection of leaks.[2]
References[edit]
- ↑ 1.0 1.1 1.2 "powergas.com". Retrieved December 16, 2025.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 "vedantu.com". Retrieved December 16, 2025.
- ↑ 3.0 3.1 3.2 3.3 3.4 "ioagpl.com". Retrieved December 16, 2025.
- ↑ "bajajfinserv.in". Retrieved December 16, 2025.
- ↑ 5.0 5.1 5.2 "plusgas.com.au". Retrieved December 16, 2025.
