Where does natural gas come from?
Before 1950, all the natural gas used in Massachusetts was manufactured from coal or oil. Today, all the natural gas used in Massachusetts comes from wells. Most of these wells are located in the southern United States or western Canada. Recently, wells in the Atlantic Ocean off of Nova Scotia have become another source of natural gas for Massachusetts and the rest of New England. The gas flows from wells through interstate transmission pipelines into the state.
How does natural gas get delivered into Massachusetts?
There are approximately 1,000 miles of interstate transmission lines in Massachusetts. They are owned and operated by three companies: Algonquin Gas Transmission Company, Tennessee Gas Pipeline Company, and Maritimes and Northeast Pipelines Company. Most of these lines are between twelve and 24 inches in diameter. They usually operate at pressures between 400 and 750 pounds per square inch ("psi").
In addition to gas delivered by transmission lines, Massachusetts also uses liquefied natural gas ("LNG") which is delivered by ship to the Distrigas terminal in Everett. Most of the LNG comes from Algeria and Trinidad. The LNG is shipped by truck to LNG plants in the state. It is stored at these plants for use in the winter months when demand is high.
How does natural gas get delivered to my house?
Each of the seven local distribution companies ("LDCs") and four Municipal Gas Departments in Massachusetts has a distribution system connected to the transmission companies' pipelines at meter stations throughout the state. These stations (also called take stations or city gates) have two purposes: measurement of gas quantity, and pressure control. The transmission companies measure the amount of gas flowing into each station. The LDCs reduce the pressure of the gas from the transmission lines to match the pressure of their distribution systems.
The gas pressure is controlled by regulators, a special type of valve. The regulators can reduce the gas pressure. If the gas pressure rises above set limits, regulators can also shut off the gas flow entirely.
What sort of pipes deliver the gas to my house?
The distribution systems are composed primarily of two types of pipelines: mains and services. Mains are the pipelines that carry the gas from the meter stations throughout the distribution systems. They are usually between two inches and 16 inches in diameter. The gas pressure ranges from 1/4 psi to 200 psi. They are made of steel, plastic, or cast iron. There are approximately 21,000 miles of mains in the state.
Services carry the gas from the main to your gas meter. They are usually 1/2 inch to 1 1/2 inches in diameter and made of steel or plastic pipe. The pressure in a service is the same as the pressure in the main to which it is connected.