Difference between LPG, LNG, PNG, and CNG
Context:
As geopolitical tensions in West Asia and disruptions at the Strait of Hormuz threaten global supply chains, India’s heavy reliance on imported cooking gas has come under sharp focus.
Consequently, the government is accelerating the shift from imported Liquefied Petroleum Gas (LPG) to Piped Natural Gas (PNG) relying on domestic natural gas production to secure energy availability and reduce the import bill
Key Conceptual Differences:
While all four fuels are vital components of India's energy ecosystem, they differ significantly in their chemical composition, state of matter during transport, and primary applications.
LPG (Liquefied Petroleum Gas):
A byproduct of crude oil refining and natural gas processing, it is easily liquefied under moderate pressure.
It is stored and distributed in pressurized metal cylinders.
Notably, LPG is heavier than air; in case of a leak, it settles near the ground, increasing the risk of an explosion.
LNG (Liquefied Natural Gas):
To transport natural gas over oceans where pipelines are unfeasible, it is super-cooled (cryogenically) to extremely low temperatures (below -160°C).
This shrinks its volume by 600 times, turning it into a liquid.
It requires highly specialized cryogenic ships and tanks.
PNG (Piped Natural Gas):
This is natural gas delivered directly to household or industrial consumers via a vast pipeline network.
Unlike LPG, it provides an uninterrupted, metered supply without the need for cylinder bookings.
It is lighter than air, meaning it safely dissipates upwards if a leak occurs.
CNG (Compressed Natural Gas):
Instead of liquefying natural gas, it is compressed to a very high pressure (200–250 kg/cm²).
It remains in a gaseous state and is primarily used as a cleaner alternative to petrol and diesel in vehicles.
Table: Comparison of Gas Types
Feature
LPG
LNG
PNG
CNG
Primary Component
Propane & Butane
Methane
Methane
Methane
Physical State
Liquid under pressure
Liquid(Cryogenic)
Gas
Gas (Highly Compressed)
Primary Delivery
Cylinders via trucks
Cryogenic ships /tankers
Direct Pipelines
High-pressure tanks (Vehicles)
Main Application
Household cooking, rural areas
Bulk international transport
Household cooking, urban grids
Automobile fuel