methane

Methane, with the chemical formula CH4, is the simplest alkane and the major component of natural gas. It is a colorless, odorless gas at room temperature; for safety, odorants such as mercaptans are added in distribution systems to enable leak detection.

Methane has a tetrahedral molecular geometry with one carbon atom bonded to four hydrogen atoms (sp3 hybridization). It is nonpolar and relatively inert under ambient conditions, but it burns readily when mixed with an oxidizer or can react under high temperature or catalytic conditions. Its boiling point is −161.5°C, and it exists as a gas at standard conditions.

Methane is produced both geologically and biologically. Geologically, it is the principal component of natural gas and can form in methane hydrates in sediments. Biologically, methane is produced by methanogenic archaea in anaerobic environments such as wetlands, landfills, and the guts of ruminant animals, as well as in rice paddies. Industrially, it is obtained from natural gas and crude oil reservoirs and can be produced from biogas by upgrading. It is also used as a chemical feedstock, notably in hydrogen production via steam methane reforming and in the synthesis of basic chemicals.

Methane is a potent greenhouse gas, with a global warming potential much higher than carbon dioxide on a 100-year timescale, largely due to its infrared absorption properties and relatively short atmospheric lifetime. It is also flammable and forms explosive mixtures with air in certain concentrations. Gas leaks and venting during extraction, transport, and use are ongoing environmental concerns; mitigation strategies include leak detection, repair, and gas capture from landfills, agriculture, and energy infrastructure.