Methane is a chemical compound with the chemical formula CH 4. It is the simplest alkane and the main component of natural gas. Natural gas occurs in reservoirs beneath the surface of the earth. It is often found in conjunction with petroleum deposits. Before it is distributed, natural gas usually undergoes some sort of processing.
Usually, the heavier hydrocarbons (propane and butane) are removed and marketed separately. Non-hydrocarbon gases, such as hydrogen sulfide, must also be removed. The cleaned gas is then distributed throughout the country through thousands of miles of pipeline. Local utility companies add an odorant before delivering the gas to their customers.
Natural gas is the cleanest burning fossil fuel. Coal and oil, the other fossil fuels, are more chemically complicated than natural gas, and when combusted, release a variety of potentially harmful air pollutants. Burning methane releases only carbon dioxide and water. Since natural gas is mostly methane, the combustion of natural gas releases fewer byproducts than other fossil fuels.
At room temperature, methane is a gas less dense than air. It melts at –183°C and boils at –164°C. It is not very soluble in water.
Methane is a potent greenhouse gas with a global warming potential more than 25 times greater than that of carbon dioxide. If methane is allowed to leak into the air before being used—from a leaky pipe, for instance—it absorbs the sun’s heat, warming the atmosphere. For this reason, it’s considered a greenhouse gas, like carbon dioxide.
The largest source of industrial emissions of methane is the oil and gas industry. Nearly 30 percent of methane emissions in the U.S. in 2012 came from oil production and the production, processing, transmission and distribution of natural gas.
While methane emissions from the oil and gas industry have declined 16 percent since 1990, they are projected to increase by about 25 percent over the next decade.