Methanes

Methane, with chemical formula CH4, is the simplest alkane and a major hydrocarbon in the Earth's atmosphere and economy. It is a colorless, odorless gas at room temperature, though natural gas is usually odorized for safety. Methane has a tetrahedral molecular geometry and a boiling point of −161.5 °C. It is sparingly soluble in water and is lighter than air.

Methane occurs both naturally and commercially. Biogenic methane forms in anaerobic environments such as wetlands, rice paddies, landfills, and the guts of ruminant animals. Thermogenic and abiogenic sources contribute methane from geological formations, natural gas reservoirs, and methane-rich hydrates. In the atmosphere, methane is a potent greenhouse gas with a lifetime of about a decade to a dozen years and a global warming potential higher than carbon dioxide on a per-molecule basis over timescales of 20 to 100 years.

Industrial production and use are centered on methane as a feedstock and energy source. It is the primary component of natural gas and is used for electricity generation, heating, and as a chemical feedstock. Chemically, methane can be converted to syngas (a mixture of hydrogen and carbon monoxide) via steam reforming, which serves as a starting point for the production of hydrogen, methanol, and other chemicals. It can also undergo halogenation or combustion to yield carbon dioxide and water.

Safety and environmental considerations are important. Methane is highly flammable and can form explosive mixtures with air. Reducing methane leaks and controlling emissions is a key part of climate and energy policy due to its strong short- and long-term warming effects.