Natural Gas Production and Distribution
Most natural gas consumed in the United States is domestically produced. The vast majority of natural gas in the U.S. is considered a fossil fuel because it is made from sources formed over millions of years by the action of heat and pressure on organic materials.
Natural gas is primarily extracted from gas and oil wells, while smaller amounts can be made from supplemental sources, such as biomass and coal. Gas trapped in subsurface porous rock reservoirs is extracted via drilling. Gas streams produced from oil and gas reservoirs contain natural gas, liquids, and other materials. Also, advances in hydraulic fracturing technologies enabled access to large volumes of natural gas from shale formations.
The U.S. Environmental Protection Agency (EPA) is working to ensure that natural gas extraction does not come at the expense of public health and the environment (see EPA's hydraulic fracturing information).
Once extracted, the gas is separated from free liquids, such as crude oil, hydrocarbon condensate, water, and entrained solids. The separated gas is further processed to meet specified requirements. For example, natural gas for transmission companies must generally meet certain pipeline quality specifications with respect to water content, hydrocarbon dew point, heating value, and hydrogen-sulfide content.
Although natural gas is a mixture of hydrocarbons, it is predominantly made up of methane (CH4). As delivered through the pipeline system, natural gas also contains additional hydrocarbons, such as ethane and propane, as well as other gases, such as nitrogen, helium, carbon dioxide, hydrogen sulfide, and water vapor. (See the Fuel Properties.)
A dehydration plant controls water content, a gas-processing plant removes certain hydrocarbon components to hydrocarbon dew point specifications, and a gas-sweetening plant removes hydrogen sulfide and other sulfur compounds (when present).
To learn more, see Franklin County Sanitary Landfill - Landfill Gas (LFG) to Liquefied Natural Gas (LNG) Project and the Energy Information Administration's Natural Gas Analysis and Projections).
The United States has a vast natural gas distribution system, which can quickly and economically distribute natural gas to and from almost any location in the lower 48 states. Gas is distributed using 300,000 miles of transmission pipelines (see map), while an additional 1.9 million miles of distribution pipes transport gas within utility service areas. The distribution system also includes thousands of delivery, receipt, and interconnection points; hundreds of storage facilities; and more than 50 points for exporting and importing natural gas.
Most natural gas fueling stations dispense compressed natural gas (CNG), which is compressed on site in most cases. The availability of liquefied natural gas (LNG) stations is more limited. Most LNG users are fleets that have LNG infrastructure dedicated to their vehicles. Only a few large-scale liquefaction facilities provide LNG fuel for transportation nationwide. LNG must be delivered to stations via trucks.