However, consumer bills are usually measured in heat content or therms. One therm is a unit of heating equal to 100,000 Btu. Three segments of the natural gas industry are involved in delivering natural gas from the wellhead to the consumer. Production companies explore, drill and extract natural gas from the ground. Transmission companies operate the pipelines that link the gas fields to major consuming areas.
Distribution companies are the local utilities that deliver natural gas to the customer.
About 46 percent of natural gas delivered to U.S. consumers is used in the industrial sector, providing energy for everything from mining minerals to processing food. Generating electricity consumes about 15 percent. Natural gas is delivered to about 175 million American consumers through a 1.3 million-mile network of underground pipe. The United States accounts for about 24 percent of the world's natural gas production each year. The American Gas Association is a trade organization that represents natural gas distribution companies.