Liquefied natural gas
Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume of natural gas in the gaseous state at standard temperature and pressure.
LNG is odorless, colorless, non-toxic, and non-corrosive. Hazards include flammability after vaporization into a gaseous state, freezing and asphyxia. The liquefaction process involves removal of certain components, such as dust, acid gases, helium, water, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid at close to atmospheric pressure by cooling it to approximately −162 °C (−260 °F); maximum transport pressure is set at around 127 kPa (18 psi) (gauge pressure), which is about 1.25 times atmospheric pressure at sea level. The gas stream is typically separated into the liquefied petroleum fractions (butane and propane), which can be stored in liquid form at relatively low pressure, and the lighter ethane and methane fractions. These lighter fractions of methane and ethane are then liquefied to make up the bulk of LNG that is shipped.
Before the late 20th century, natural gas was largely considered a byproduct of oil production. The development of production processes, cryogenic storage, and transportation made it possible to commercialize natural gas, creating a global market which now competes with other fuels. The development of LNG storage made natural gas transportation much more reliable. Unlike simple tanks used for other fuels, natural gas could not be stored for extended periods due to the difficulty of preventing gas leakage. Large-scale cryogenic storage, it became possible to construct reliable long term storage reserves for natural gas as well. These reserves of liquefied gas could be deployed at a moment's notice through regasification processes, and today are the main means for networks to handle local peak shaving requirements.
Production of LNG is concentrated in a few countries where the energy intensive process, and typically requires specialized ports for handling the export of the LNG for use in other countries. As of 2023, the United States, Australia and Qatar had the most capacity for exporting LNG, and China Japan and South Korea were the biggest importers. A 2025 report by the IEA, found that more capacity would be coming on in the upcoming decade. This hyper concentration of production creates choke points in global supply chains, with the 2026 War in Iran effecting Qatar's LNG exports, causing a ripple effect in LNG access and cost.