A Primer on Natural Gas
atural gas is a combustible, gaseous mixture of simple hydrocarbon compounds, usually found in deep underground reservoirs of porous and permeable rocks. Natural gas is a fossil fuel composed largely of methane. A molecule of methane, the simplest and lightest hydrocarbon, consists of one carbon atom surrounded by four hydrogen atoms. Natural gas also contains lesser amounts of “higher” hydrocarbon gases, that is, those of greater molecular weight, namely ethane, propane, butane, isobutane and pentane (together commonly referred to as
C2+), as well as variable concentrations of nonhydrocarbon gases, namely carbon dioxide, nitrogen, hydrogen sulﬁde and helium (see sidebar, Composition of Natural Gas).
Natural gas is the cleanest burning fossil fuel, producing smaller amounts of combustion by-products than either coal or reﬁned oil products.
Why Is Natural Gas
The ﬁrst practical use of natural gas in the United States dates from 1821 in Fredonia, New York, where a crudely drilled well and hollowed-out log pipes were used to deliver gas from a natural seep to nearby homes for lighting.70 Not until the 1880s, however, did natural gas for home heating and lighting and for industrial use become prevalent. By the late 1940s natural gas had all but replaced the use of
“illuminating” gas manufactured from coal and wood. The
Director, Potential Gas Agency, Colorado School of Mines, Golden,
Stephen D. Schwochow
Geological Consultant/Editor, Golden, Colorado.
Potential Supply of Natural Gas—2008
According to statistical data from the U.S. Department of
Energy’s Energy Information Administration (EIA) for
2008, natural gas satisﬁed 24 percent of the nation’s energy demand (consumption), moving ahead of coal, which remained steady at 22.6 percent. Crude oil and natural gas liquids, while still accounting for the largest share, declined from a recent high of 40 percent (2004–06) to 37.4 percent.
Nuclear power rose slightly to 8.5 percent, and hydropower and renewables totaled 7.4 percent.71
Composition of Natural Gas
Natural gas has become the “fuel of choice” in many residential, commercial and industrial applications. Furthermore, natural gas has become particularly important in electric power generation. The natural gas you conveniently consume in your home or business is the end result of an entire industry working together to ﬁnd, produce and deliver a safe, clean and reliable energy resource.
Dr. John B. Curtis
transition was facilitated in part by federal regulations that discouraged oil ﬁeld operators from wasting natural gas by venting and ﬂaring. An unknown but likely enormous volume of gas resource was lost through such practices.
Nevertheless, natural gas became a marketable commodity, and production ﬂourished. In the years following World War
II, the interstate pipeline system, which was begun in 1925, was greatly expanded, thereby bringing natural gas service to consumers all over the Lower 48 United States.
Hydrocarbon gases Methane Ethane Propane Butane Pentane Hexane
C5H12 trace C6H14 trace Nonhydrocarbon gases Carbon dioxide Nitrogen Hydrogen sulﬁde Water vapor Helium
N (or N2) 1–4%
H2 S variable H2 O variable He trace 70. Peebles, M.W.H., 1980, Evolution of the Gas Industry: New York, New
York University Press, 235 p.
71. Energy Information Administration Ofﬁce of Energy Markets and End
Use, 2009, Annual Energy Review 2008: U.S. Dept. of Energy, Energy
Information Administration, Rept. DOE/EIA-0384(2008), June, 407 p.
Available online at http://www.eia.doe.gov/aer.
©2010 Potential Gas Committee
Natural Gas Primer • 193
Where does our natural gas come from?