Liquefied natural gas, or LNG, is gas cooled into a liquid so it can be transported and stored in a much smaller volume. This technology connects remote fields to markets not served by a pipeline. It opens new outlets for producers but relies on an expensive, energy-intensive industrial chain sensitive to technical and geopolitical disruptions. Since 2025, production at Grand Tortue Ahmeyim has also brought Senegal and Mauritania into this global industry.
Key facts
- Definition: natural gas cooled to approximately −162 °C at atmospheric pressure.
- Volume reduction: approximately 600 times compared with its gaseous state.
- Value chain: treatment, liquefaction, storage, LNG carrier transport, regasification and distribution.
- West Africa: the shared Grand Tortue Ahmeyim project began producing LNG in 2025.
What is LNG?
LNG consists primarily of methane. It is obtained by cooling natural gas to approximately −162 °C at atmospheric pressure. At this temperature, the gas condenses into a clear liquid occupying approximately 600 times less volume than the same gas in its gaseous state. This density makes long-distance shipping possible.
LNG should not be confused with liquefied petroleum gas (LPG), consisting mainly of propane and butane. LPG is liquefied by pressure or moderate cooling; LNG requires very low cryogenic temperatures. Installations, tanks and uses are therefore not interchangeable.
Why liquefy gas?
A pipeline efficiently transports large quantities of gas between territories connected by continuous infrastructure. But building one is not always possible or economically appropriate, particularly when markets are separated by an ocean or far from the field. LNG then enables maritime gas transport and supplier diversification.
This flexibility has a counterpart: investment is needed in a liquefaction plant, cryogenic tanks, specialized LNG carriers and terminals able to receive and then regasify cargoes. Every stage requires capital and equipment subject to strict safety standards.
Stages of the LNG value chain
1. Extract and treat the gas
Gas is transported from the field to a treatment facility. It sometimes contains water, carbon dioxide, hydrogen sulfide, nitrogen or heavier hydrocarbons. These components are separated according to field characteristics and plant requirements. Purification prevents ice or hydrate formation and protects equipment during cooling.
2. Cool and liquefy
Treated gas is precooled, then progressively cooled through refrigeration cycles to approximately −162 °C. Molecules enter the liquid state, facilitating storage and transport. Installations use large quantities of energy to run compressors and heat exchangers. Part of the gas received generally serves the chain’s own needs, affecting overall efficiency.
Liquefaction can take place onshore at a coastal terminal or offshore aboard a floating unit known as FLNG. The latter combines treatment and liquefaction equipment on a maritime installation. It can enable development of fields far from shore, but offshore maintenance and operation impose particular constraints.
3. Store and transport
LNG is kept in thermally insulated tanks. It is then loaded onto LNG carriers whose tanks keep the product at very low temperatures. During the voyage, a small portion of the liquid can warm and vaporize: this boil-off gas can be recovered and used as fuel or reliquefied, depending on the vessel and installed system.
Shipping directly links exporting and importing terminals but depends on vessel availability, routes and port slots. A disruption in a strait, plant breakdown or construction delay can therefore change available supply and prices across several markets.
4. Regasify and deliver
On arrival, LNG is unloaded into cryogenic tanks. When the network needs it, it is warmed at a regasification terminal. Methane returns to its gaseous state, its quality is checked and it can be injected into a pipeline to reach power plants, industrial facilities or distribution networks.
Floating solutions or truck deliveries can serve customers far from networks, provided suitable infrastructure and financially viable demand exist.
A global chain, but with costs and emissions
The buyer’s price includes extraction, treatment, liquefaction, transport, regasification and contracts. The chain is more complex and energy-intensive than a pipeline; prices vary with seasons, competition and cargo availability.
Its climate footprint extends beyond final combustion. Emissions from extraction, treatment, liquefaction, transport and methane leaks must also be considered. In 2026, the International Energy Agency assessed average emissions intensity across the global LNG chain at 18.6 grams of CO₂ equivalent per megajoule delivered, from production to regasification. This average covers substantial differences between sites and practices. Controlling leaks and energy consumption is therefore decisive.
LNG in West Africa
Grand Tortue Ahmeyim (GTA), offshore Senegal and Mauritania, illustrates this chain’s complexity. Offshore gas is treated aboard a floating production, storage and offloading unit, then directed to a floating liquefaction facility. The first phase is designed to produce approximately 2.3–2.5 million metric tons of LNG annually. LNG production began in 2025, making both countries new participants in the global market.
Developing this resource can generate export revenues, strengthen local skills and support related activities. National benefits will nevertheless depend on actual production volumes, revenue-sharing arrangements, local content and gas access for domestic markets. Exports and supply to national economies must be planned together, with appropriate infrastructure and contracts.
Frequently asked questions
Is LNG a different gas from natural gas?
No. It is the same gas, primarily methane, but cooled into a liquid. It returns to its gaseous state during regasification at the import terminal.
Why does an LNG carrier not transport gas in its gaseous form?
In liquid form, gas occupies approximately 600 times less volume. Ships can thus carry large quantities without maintaining pressure as high as that required for compressed gas.
Is LNG emissions-free?
No. Its combustion emits CO₂, and the supply chain can also produce methane emissions and consume energy. Its footprint depends on every stage, from the field to final use.