There are two general types of energy pipelines – liquid petroleum pipelines and natural gas pipelines.
Within the liquid petroleum pipeline network there are crude oil lines, refined product lines, highly volatile liquids (HVL) lines, and carbon dioxide lines (CO2). Crude oil is also subdivided in to 'Gathering Lines' and ’Transmission Lines”.
First, gathering lines are very small pipelines usually from 2 to 8 inches in diameter in the areas of the country where crude oil is found deep within the earth. These gathering lines exist all over the country but the bulk of them are located primarily in Texas, North Dakota, California, Oklahoma, New Mexico, Louisiana, and Wyoming with small systems in a number of other oil producing states.
The larger cross-country crude oil transmission pipelines or trunk lines bring crude oil from producing areas to refineries. There are approximately 72,000 miles of crude oil system lines (usually 8 to 24 inches in diameter) in the United States that connect regional markets. There are also a few VERY large trunk lines. One of the largest in the U.S. is the Trans-Alaska Pipeline System, which is 48 inches in diameter.
The next group of liquid petroleum pipelines is one that carries refined petroleum products – gasoline, jet fuel, home heating oil and diesel fuel. These refined product pipelines vary in size from relatively small, 8 to 12 inch diameter lines, to much larger ones that go up to 42 inches in diameter. There are approximately 63,000 miles of refined products pipelines nationwide. They are found in almost every state in the U.S. These pipelines deliver petroleum products to large fuel terminals with storage tanks that are then loaded into tanker trucks. Trucks cover the last few miles to make local deliveries to gas stations and homes. Major industries, airports and electrical power generation plants are supplied directly by pipeline.
Highly volatile liquid (HVL) lines and carbon dioxide (CO2) lines are also a part of the liquid petroleum pipeline network. These liquids turn to gas once exposed to the atmosphere. They include ethane, butane and propane. Carbon dioxide pipelines allow carbon dioxide to enhance oil recovery, as CO2 has long done in North America.
The natural gas pipeline system is organized somewhat differently. Natural gas, unlike oil, is delivered directly to homes and businesses through pipelines.
Natural gas can contain natural gas liquids (NGL) when produced. Processors remove water, NGLs, and impurities from the natural gas stream to make the natural qas suitable for sale. Natural gas and NGLs then travel on separate pipeline systems. It is determined to be "rich" or "wet" if it contains signiﬁcant natural gas liquids (NGL); by contrast, natural gas is known to be "lean" or "dry" if it does not contain these liquids.
The U.S. natural gas pipeline network is a highly integrated transmission and distribution grid that can transport natural gas to and from nearly any location in the lower 48 states. It consists of more than 210 natural gas pipeline systems and 300,000 miles of interstate and intrastate transmission pipelines.