Natural Gas Processing, Delivery and Storage
Natural gas is delivered to about 175 million American consumers through a 1.3 million-mile network of underground pipe. A total of 285,000 natural gas wells, 125 natural gas pipeline companies, and more than 1,200 gas distribution companies provide gas service to all 50 states.
From its source at a wellhead, natural gas goes through a series of production, transmission and distribution porcesses enroute to its final use at your home or business.
Before natural gas is distributed, it first must be sent to a processing or "stripping" plant where it is cleaned and separated. At the processing plant, the natural gas is sent through a separator where secondary byproducts (including oils and impurities) and heavier hydrocarbons (including butane, ethane, and propane) are removed. Most of these byproducts are reprocessed, packaged and sent to market.
As natural gas leaves the processing plant, it enters a compressor station where it is pressurized for transmission. As the pressure is increased, the volume of natural gas is reduced and more natural gas can be filled into the same unit space while the pressure needed to move natural gas through pipelines is achieved.
As natural gas travels through pipelines, some pressure is lost due to fluid friction caused by the natural gas rubbing against the inside walls of the pipes. This loss of pressure is made up at compressor substations located every 50 to 100 miles along the transmission pipelines.
Upon reaching a major metropolitan area, some natural gas is diverted through a "city gate" where its pressure is reduced, measured, and sold to the local gas company. From the city gate, the natural gas company distributes the natural gas through an underground network of smaller pipelines called "mains." Smaller lines called "services" connect with the mains and go directly to end-users.
Natural Gas Storage
In summer months, when the demand for natural gas is low, natural gas companies can store their excess supply in a number of ways. The most common method is to pipe the natural gas into depleted oil or natural gas reservoirs where it can be stored indefinitely and withdrawn as needed.
Underground storage is used to meet peak winter demand when the capacity of the pipelines cannot deliver what is needed. There are more than 380 underground storage systems operated by 80 companies in 26 states. More than half of the total underground storage systems are located in Illinois, Michigan, Pennsylvania, Ohio and West Virginia.
Another storage method is converting natural gas to liquid. By reducing its temperature to -259 degrees Fahrenheit, natural gas can be condensed into liquefied natural gas (LNG) which takes up only 1/600th of the space it does as a gas. When LNG is ready to be used, it can be easily converted back to a gaseous form simply by increasing the temperature.