Natural gas is a gaseious fossil fuel consisiting primarily of methane and including amounts of ethane, propane, butane and pentane. Natural gas is also discussed under the “Geothermal Energy” article.

Natural gas can be found in oil fields, dissolved or isolaed natural gas fields, and in coal beds. When methane rich gases are produced by the decay of non-fossil organic material, they are referred to as biogas. Biogas can be found in swamps, marshes, and landfills, sewage sludge and manure by using anaerobic digesters and enteric fermentation in cattle.

Natural gas is a major source of electricity generation thru the usage of gas turbines, and steam turbines. Particularly high efficiencies can be achieved through combining gas turbines with a steam turbin in combined cycle mod. Natural gas is about cleanest burning fossil fuel and produces roughly 35% less carbon dioxide then petroleum and about 45% less then coal. Fuel cell technology may eventually provide cleaner options for convertiing natural gas into electricity, but as it is not yet price-competitive.