- The natural gas used by consumers is almost exclusively methane, a simple molecule consisting of one carbon and four hydrogen atoms. When burned in the presence of oxygen, it produces carbon dioxide and water. As it is found in the earth, however, natural gas usually contains large amounts of ethane, propane, butane and pentane. Like all fossil fuels, natural gas is produced by the breakdown of organic material over millions of years and is therefore considered a nonrenewable resource. Though large amounts of natural gas remain untapped, bottlenecks in storage in transportation occasionally produce supply shortages. More than 63 million homes in the United States use natural gas directly or energy derived from it. About 13 percent of all natural gas is used to power business and public buildings.
- Like oil, natural gas deposits are located deep beneath the earth's surface. The gas is brought to the surface in pipes through the drilling of deep wells, sometimes aided by the pumping of pressurized gas into the wells. From the wells, which can be scattered over large geographical regions, the gas moves through "gathering" lines to a central collection point. Here, the gas can be move through a processing plant that segregates the heavier distillates like ethane and butane for other uses. The remaining methane-rich gas is also treated to remove sulfur, mercury and nitrogen before released for distribution.
- From the processing plants, natural gas is transported to local natural gas utilities through a 150,000 mile network of underground pipe. Made of high-strength steel ranging from 20 inches to 42 inches in diameter, this network relies on compressor stations ever 70 miles or so to pressurize the gas and keep it moving at about 15 miles per hour. At the utility company, a chemical is added to the methane gas to give it the telltale odor that alerts consumers to a leak. It is then transported through underground gas mains that act like major streets that branch off to individual homes and businesses. Transport through underground pipe is economical over land, but because of the need for frequent pressurization is not practical across oceans and seas. In these situations, natural gas is usually supercooled until it condenses into a liquid. This liquefied natural gas (LNG) can be transported in trucks and ships.
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