Natural gas
Overview
Natural gas is a hydrocarbon gas deposited in underground strata, composed mainly of methane (CH4). Along with coal and petroleum, it is one of the fossil fuels, and because its carbon dioxide emissions upon combustion are relatively low, it is sometimes called a "clean fuel." It occupies a significant share of the global energy mix and is used in various fields such as heating, power generation, and industrial feedstocks.
Main content
Properties and composition
The main component of natural gas is methane, with small amounts of heavier hydrocarbons such as ethane, propane, and butane, as well as nitrogen, carbon dioxide, and hydrogen sulfide. It is colorless and odorless, and since leaks are dangerous, an odorant (mercaptan) is added to commercial gas. It is lighter than air and has a narrow explosive range, making it relatively safe, but there is a risk of asphyxiation in enclosed spaces. Its calorific value is about 10,000–11,000 kcal per 1 m³, and LNG (liquefied natural gas) has a high energy density per unit volume.
Discovery and production
Natural gas is mainly produced from oil fields or gas fields. Because of the high pressure inside the strata, it gushes out naturally upon drilling or is extracted using pumps. Recently, the production of gas trapped in rock, such as shale gas, using hydraulic fracturing (fracking), has also increased. Major producers include the United States, Russia, Iran, Qatar, China, and others. Reserves continue to be discovered, and including unconventional gas reserves, the total is estimated to be enough for several decades.
Storage and transport
Natural gas is transported in a gaseous state via pipelines or liquefied and shipped on LNG carriers. Pipelines are mainly suitable for intracontinental transport, while intercontinental or maritime transport uses LNG, which is cooled to −162°C to reduce its volume to 1/600. LNG is stored in insulated tanks, and carriers are equipped with specially designed membrane tanks. Underground salt formations and refrigeration tanks are used as storage facilities. Recently, floating LNG production, storage, and offloading facilities (FLNG) have also been commercialized.
Uses
Natural gas is used in many areas, including power generation, city gas, industrial use, and transportation. In electricity production, gas turbine combined-cycle power generation has high efficiency and low CO2 emissions, making it the most environmentally friendly among fossil fuels. As city gas, it is used for heating, cooking, and hot water supply; in industry, it is used as fuel for heat treatment processes such as steel, glass, and ceramics. It is also important as a feedstock for reforming processes that produce hydrogen and is essential for ammonia and fertilizer production. In transportation, vehicles using CNG (compressed natural gas) or LNG fuel are used to some extent.
Environmental impact
Natural gas emits 25–40% less carbon dioxide than coal or oil when burned and produces almost no particulate matter or sulfur oxides. However, methane itself has a greenhouse effect 28–36 times greater than that of CO2, making pipeline leaks and release during extraction significant issues. Groundwater contamination and induced seismicity from hydraulic fracturing are also controversial. Therefore, natural gas is classified as a "bridge fuel" in the context of climate change response, but in the long term, a transition to a low-carbon energy system is required.
Prices and markets
International gas prices are linked to oil prices, and major benchmarks include the US Henry Hub, the UK NBP (or European TTF), and the Japanese LNG CIF. Because pipeline exports were common, regional price differences were large in the past, but with increasing LNG demand and greater trading flexibility, a global LNG market has emerged and price correlations have strengthened. Geopolitical crises such as Russia's invasion of Ukraine caused sharp fluctuations in gas prices, heightening the importance of energy security and price stabilization.
Latest trends
As of 2024–2025, the natural gas market has been reshaped by reduced Russian pipeline gas supplies and Europe's expanded LNG imports. The United States has emerged as the largest LNG exporter, while Qatar and Australia are pursuing large-scale expansions. China is increasing imports, mainly for power plants and industrial demand. Meanwhile, there are forecasts that gas demand will decline in the long term in line with implementation of the Paris Agreement and carbon neutrality goals. As renewable energy expands, the role of gas as backup power to complement variable electricity supply and demand is emphasized. Its role as a bridge to low-carbon hydrogen production is also drawing attention in connection with the hydrogen economy. Regulatory instruments, such as satellite monitoring technologies and the Global Methane Pledge, are being strengthened to reduce methane leaks.
Related topics
- [[Petroleum]]
- [[Liquefied natural gas]]
- [[Shale gas]]
- [[Energy transition]]
- [[Hydrogen energy]]