Methane is a naturally occurring, combustible gas that is colourless and odourless. Methane is the primary component of natural gas; 97 per cent (by volume) of natural gas is methane. The different names for methane include: R 50, marsh gas, biogas and fire damp. Methane is widely used all over the world in homes, businesses and factories. In homes and businesses, it is used for cooking and heating. In the industrial sector, methane is used as a fuel for gas boilers and turbines.
The chemical composition of methane is CH4. The melting point and boiling point of methane is -296.5 degrees Fahrenheit and -14364 degrees Celsius respectively. Since methane is an odourless gas, an odorant is added to the methane supplied to homes, so leaks can be detected. Methane is extremely flammable in the presence of oxygen; inhaling methane can be life threatening because it causes asphyxiation by displacing the surrounding oxygen. Methane can also be stored in liquid form, which is only flammable under high atmospheric pressure.
Methane comes from a number of different sources, hence the different names; underground deposits of natural gas are the primary source of methane. Methane is also trapped in little pockets near coal deposits. Other natural sources of methane emissions include: wetlands, termites, oceans, methane hydrates, mud volcanoes, wildfires and wild animals.
Man-made sources of methane include landfills, manure management (biogas), waste water treatment and rice cultivation. According to the U.S Environmental Protection Agency (EPA), landfills account for 34 per cent of all methane emissions in the United States.
Methane is primarily used as fuel in homes and industries. The methane delivered to homes is generally referred to as natural gas. Compressed methane, also called compressed natural gas (CNG), is an alternative source of vehicle fuel. CNG is cheaper and more eco-friendly than petrol and diesel. In the industrial sector, methane is mixed with carbon dioxide and hydrogen to produce other chemicals, such as methanol, acetic anhydride and acetic acid. Other chemicals produced from methane include the chloromethanes and acetylene.
Methane is termed by the EPA as a "greenhouse gas." Atmospheric methane traps infrared radiation from the earth, which causes a rise in the atmospheric temperature. Once in the atmosphere, methane can linger for around 12 years. According to the EPA, there is around 220 times more carbon dioxide in the air than methane, but methane is nearly 21 times more potent than carbon dioxide at increasing atmospheric temperature over a hundred years. The northern hemisphere has a larger concentration of atmospheric methane due to the concentration of human and natural sources of methane emissions.