“LNG (Liquefied Natural Gas) is natural gas (primarily methane) that has been cooled to approximately -165°C (-265°F) to turn it into a liquid. This process reduces the gas’s volume by about 600 times.” – LNG (Liquefied Natural Gas)
Liquefied natural gas (LNG) represents a critical innovation in energy storage and transportation, enabling natural gas to be moved across continents and oceans where pipeline infrastructure is impractical or impossible. The transformation from gas to liquid occurs through an energy-intensive cooling process that fundamentally changes the physical properties and practical applications of natural gas.
Definition and Physical Properties
LNG is natural gas that has been cooled to approximately ?162°C to ?163°C (?260°F to ?265°F) at atmospheric pressure, converting it from a gaseous state into a clear, colourless, and odourless liquid. This cryogenic process reduces the volume of natural gas by approximately 1/600th of its original gaseous volume, making it economically viable for long-distance maritime transport. The composition of LNG is predominantly methane (CH4), typically comprising more than 90 percent of the final product, with smaller quantities of ethane (C2H6), propane, butane, and trace amounts of nitrogen and heavier hydrocarbons.
In its liquid state, LNG is non-flammable and non-combustible, which significantly reduces safety risks during storage and transportation. The liquid is also non-toxic and non-corrosive, making it suitable for handling in specialised facilities. However, the cryogenic nature of LNG presents distinct hazards: the extremely cold liquid will freeze any material it contacts, and rapid phase transition explosions (RPT) can occur when cold LNG comes into contact with water.
Energy Density and Comparative Value
The energy content of LNG varies depending on its source and the liquefaction process employed, typically ranging within ±10 to 15 percent of standard values. The higher heating value of LNG averages approximately 50 MJ/kg (21,500 BTU/lb), whilst the lower heating value is approximately 45 MJ/kg (19,350 BTU/lb). When expressed as volumetric energy density, LNG contains approximately 22.5 MJ/litre (based on higher heating value), with a density ranging from 0.41 to 0.5 kg/litre depending on temperature, pressure, and composition.
The volumetric energy density of LNG is approximately 2.4 times greater than compressed natural gas (CNG), making it substantially more economical for long-distance transport by ship. However, LNG’s energy density is only approximately 60 percent that of diesel and 70 percent that of petrol, limiting its application as a direct transportation fuel in most contexts.
The Liquefaction Process
The liquefaction process begins with extensive pre-treatment of raw natural gas feedstock to remove impurities that would either freeze at cryogenic temperatures or damage liquefaction equipment. These impurities include hydrogen sulphide (H2S), carbon dioxide (CO2), water (H2O), mercury, benzene, and higher-chained hydrocarbons. The purification process is designed to ensure the distributed gas remains non-corrosive and non-toxic, with specific limits on sulphur content, CO2 levels, and mercury concentration.
Once purified, the natural gas enters the liquefaction unit where it undergoes a multi-stage cooling process. Controlled amounts of pressurised propane are used to gradually reduce the temperature of the gas. The gas is then passed over super-cooled liquids that extract additional heat, and finally nitrogen is employed to achieve the extreme temperatures necessary for complete liquefaction. The entire process is highly energy-intensive, requiring significant electrical or thermal input to achieve and maintain the necessary cryogenic conditions.
Storage, Transport, and Regasification
LNG requires specially insulated and refrigerated tanks for both storage and transport. The dramatic volume reduction-from gas to liquid-makes maritime transport economically feasible, with LNG carriers featuring distinctive large dome-shaped tanks visible above deck. This capability has transformed the global energy market by enabling natural gas to reach regions without access to pipeline infrastructure, particularly across geographical or political barriers.
To utilise LNG at its destination, the liquid must be warmed through a process called regasification, which converts it back into its gaseous state. The vaporised natural gas is then either injected into existing pipeline systems for distribution or used directly to fuel natural gas-operated equipment for electricity generation and heating applications.
Historical Development and Strategic Importance
The liquefaction process itself was developed during the 19th century, though commercial-scale LNG production and transport did not become economically viable until the latter half of the 20th century. The technology has become increasingly important to global energy security, as it provides flexibility in response to volatile demand and changing market conditions. The ability to transport natural gas via ship has decoupled natural gas markets from pipeline geography, creating a genuinely international commodity market.
Key Strategic Theorist: Daniel Yergin
Daniel Yergin stands as the preeminent strategic theorist whose work has fundamentally shaped understanding of LNG’s role in global energy markets and geopolitical strategy. Born in 1947, Yergin is an American author, speaker, and energy expert who has spent over four decades analysing the intersection of energy, economics, and international relations.
Yergin’s seminal work, The Prize: The Epic Quest for Oil, Wealth, and Power (1991), established him as the leading historian of the modern energy industry. Whilst primarily focused on petroleum, this Pulitzer Prize-winning book provided the foundational framework for understanding how energy resources shape geopolitical competition and economic development. His subsequent work, The Quest: Energy, Security, and the Remaking of the Modern World (2011), explicitly addressed the emerging importance of LNG as a transformative technology in global energy markets.
Yergin’s relationship to LNG centres on his recognition that liquefaction technology fundamentally altered the nature of natural gas as a commodity. Prior to widespread LNG adoption, natural gas was inherently regional-locked into pipeline networks that created long-term bilateral relationships between producers and consumers. Yergin’s analysis demonstrated how LNG’s development enabled natural gas to become a truly global commodity, similar to oil, with spot markets, price volatility, and the ability to redirect supply flows based on market conditions rather than fixed infrastructure.
Through his work at IHS Markit (now part of S&P Global) and his consulting firm Cambridge Energy Research Associates, Yergin has advised governments and corporations on energy strategy, consistently emphasising LNG’s role in enhancing energy security by diversifying supply sources and reducing dependence on pipeline-based monopolies. His concept of “energy security” has evolved to incorporate LNG as a critical mechanism for reducing geopolitical leverage of major pipeline suppliers, particularly in Europe and Asia.
Yergin’s influence extends to policymakers worldwide, who have relied on his analysis to justify investments in LNG infrastructure and to understand the strategic implications of LNG market development. His work has been instrumental in framing LNG not merely as a technical achievement but as a geopolitical tool that reshapes international relations and economic interdependence. His recent writings have also addressed the tension between LNG’s role in energy transition and climate change concerns, reflecting the evolving strategic context in which LNG operates.
References
2. https://en.wikipedia.org/wiki/Liquefied_natural_gas
3. https://catalysts.shell.com/en/glossary/liquefied-natural-gas
4. https://www.eia.gov/energyexplained/natural-gas/liquefied-natural-gas.php
5. https://www.ebsco.com/research-starters/chemistry/liquefied-natural-gas-lng
6. https://www.phmsa.dot.gov/pipeline/liquified-natural-gas/liquefied-natural-gas-overview
7. https://www.nrdc.org/stories/liquefied-natural-gas-101
8. https://www.pgworks.com/uploads/pdfs/LNGSafetyData.pdf
