Liquefied Natural Gas (LNG)

Liquefied Natural Gas, or LNG, is simply natural gas (mostly a gas called methane) that has been cooled down until it turns into a liquid. You can think of it like turning steam back into water by cooling it, except this "steam" is natural gas and it needs to be cooled to a very low temperature.

Why does it exist?

Natural gas in its normal gas form takes up a huge amount of space, so it is hard and expensive to move over long distances, especially across oceans where there is no pipeline. When you cool natural gas to about minus 162 degrees Celsius, it becomes a liquid and shrinks to about 1/600th of the space it took up as a gas.

This makes it possible to carry large amounts of gas in special ships or tankers, and then turn it back into gas (called regasification) once it reaches its destination.

How does it work, step by step?

1. Natural gas is taken out of the ground and cleaned to remove impurities like water and carbon dioxide.
2. It is cooled in stages inside a liquefaction plant until it becomes liquid at around minus 162 degrees Celsius.
3. The liquid is loaded onto special double-hulled ships built to keep it extremely cold during the voyage, or moved in cryogenic (very low temperature) road tankers for shorter distances.
4. At the receiving end, the LNG is warmed up at a regasification terminal, turning it back into a gas that can be sent through normal pipelines.

Where is LNG used, and why is it being tried in trains?

LNG is mainly used as a fuel for power plants, industries, city gas supply (like piped cooking gas) and, increasingly, as a transport fuel for trucks, ships and now trains. Compared to diesel, burning natural gas releases less carbon dioxide, very little sulphur, and far less particulate matter (tiny soot particles that cause air pollution) for the same amount of energy produced.

In a train engine, using LNG alongside diesel in a "dual-fuel" mode lets the engine use much less diesel per kilometre, without needing a completely new type of engine.

India's position and Indian examples

India imports most of its natural gas as LNG, since domestic production is not enough to meet demand, mainly from countries like Qatar, the United States and Russia through long-term contracts and spot purchases. In 2024, India was the world's fourth-largest LNG importer. It bought about 26 million tonnes, roughly 7% of all LNG imported worldwide.

Qatar has long been India's biggest LNG supplier, through long-term contracts. Natural gas (including LNG) is targeted to make up around 15% of India's overall energy mix by 2030, up from about 6% in 2022, as part of India's plan to move to cleaner fuels. Indian Railways ran its first LNG-diesel dual-fuel DEMU (Diesel Electric Multiple Unit) service earlier, from Rewari to Rohtak in Haryana, using compressed natural gas (CNG) rather than LNG, showing gas-diesel blending was already being tested before this newer LNG-based train.

Who are the big LNG exporters?

LNG is traded across the world by sea, so a few gas-rich countries sell to many buyers. In 2025, the three largest exporters were:

• United States: the largest exporter, with a record of about 111 million tonnes.
• Qatar: second, shipping from the Persian Gulf.
• Australia: third.

Together, these three made up about 63% of global LNG exports in 2025. Canada is a newer exporter. LNG Canada, in Kitimat on Canada's Pacific coast (British Columbia), began exports in 2025. On 29 September 2026, its partners took the final investment decision (the formal go-ahead to spend money and build) on Phase 2. This will double its capacity from 14 to 28 million tonnes a year, with operations expected in the early 2030s.

Supply security matters in this trade. LNG from Qatar must sail out through the Strait of Hormuz, a narrow sea passage (a choke point). LNG from the Pacific coast of North America can reach Asian buyers without passing such a choke point.

Commonly confused concepts

• LNG vs CNG: LNG is natural gas cooled into a liquid for easy transport over long distances; CNG (Compressed Natural Gas) is natural gas kept as a gas but squeezed to high pressure, which is more common for shorter-distance vehicle fuelling like city buses and cars.
• LNG vs LPG: LNG is mainly methane from natural gas fields; LPG (Liquefied Petroleum Gas, used in cooking cylinders) is a mix of propane and butane, usually obtained from crude oil refining or gas processing, and behaves differently in storage and use.
• Dual-fuel vs pure gas engine: A dual-fuel engine (like this train) still needs some diesel to ignite the fuel mixture and runs on a blend, while a pure gas engine is redesigned to run on gas alone without needing diesel at all.

Issues, criticism and the way forward

Building the cold-chain infrastructure needed to store and transport LNG safely, such as cryogenic tankers and refuelling points, is costly, which is why India is starting with pilot conversions on a few power cars rather than a full nationwide rollout. Natural gas, including LNG, is still a fossil fuel, so while it cuts emissions compared to diesel, it does not eliminate carbon dioxide output the way full electrification does; experts note dual-fuel trains are a bridging technology while electrification is completed on remaining routes.

The government's stated way forward is to expand electrification to the last unconnected stretches while using LNG dual-fuel technology on routes or duties where full electrification is not yet practical, such as certain shunting and short-haul diesel operations.

Concepts to Know

• Dual-fuel engine: An engine that can run on two different fuels together, here diesel and LNG, instead of only one fuel.
• Regasification: The process of warming liquefied gas back into its normal gas form so it can be used or sent through pipelines.
• DEMU (Diesel Electric Multiple Unit): A type of passenger train where diesel engines generate electricity that then powers the train's motors, commonly used for shorter suburban and regional routes.
• Choke point: A narrow sea passage that many ships must use. If war or an accident blocks it, trade through it stops.
• Final investment decision (FID): The moment a company formally agrees to spend the money and start building a big project.
• Particulate matter: Tiny solid or liquid particles released into the air, for example from diesel exhaust, that can be breathed in and harm health.