PrintThe United States consumes over 20 million barrels (840 million gallons) of petroleum products each day, almost half of it in the form of gasoline used in over 200 million motor vehicles with combined travel over 7 billion miles per day.
Gasoline is made from crude oil, which was formed from the remains of tiny aquatic plants and animals that lived hundreds of millions of years ago. These remains were covered with layers of sediment, which over millions of years of extreme pressure and high temperatures became the mix of liquid hydrocarbons (an organic chemical compound of hydrogen and carbon) that we know as crude oil.
Because crude oil is made up of a mixture of hydrocarbons, refineries break down these hydrocarbons into different products. These “refined products” include gasoline, diesel fuel, heating oil, jet fuel, liquefied petroleum gases, residual fuel oil, and many other products .
The most basic refining process is aimed at separating the crude oil into its various components. Crude oil is heated and put into a still — a distillation column — and different hydrocarbon components boil off and can be recovered as they condense at different temperatures. Additional processing follows crude distillation, changing the molecular structure of the input with chemical reactions, some through variations in heat and pressure, some in the presence of a catalyst, a substance that increases the rate of a chemical reaction without being consumed in the reaction.
The characteristics of the gasoline produced depend on the type of crude oil that is used and the setup of the refinery at which it is produced. Gasoline characteristics are also impacted by other ingredients that may be blended into it, such as ethanol. The performance of the gasoline must meet industry standards and environmental regulations that may depend on location.
In 2005, U.S. refineries produced over 90 percent of the gasoline used in the United States. Although the United States is the world’s third largest crude oil producer, less than 35 percent of the crude oil used by U.S. refineries was produced in the United States. Net petroleum imports (imports minus exports) account for 60 percent of our total petroleum consumption. About 50 percent of our petroleum imports are from countries in the Western Hemisphere, with 17 percent from the Persian Gulf, and 19 percent from Africa and 14 percent from other regions.
From Refinery to Consumer
After crude oil is refined into gasoline and other petroleum products, the products must be distributed to consumers. The majority of gasoline is shipped first by pipeline to storage terminals near consuming areas, and then loaded into trucks for delivery to individual gas stations. Gasoline and other products are sent through shared pipelines in “batches.”
Since these batches are not physically separated in the pipeline, some mixing or “commingling” of products occurs. This is why the quality of the gasoline and other products must be tested as they enter and leave the pipeline to make sure they meet appropriate specifications. Whenever the product fails to meet local, state, or federal product specifications, it must be removed and trucked back to a refinery for further processing.
After shipment through the pipeline, gasoline is typically held in bulk storage terminals that often service many companies. At these terminals the gasoline is loaded into tanker trucks destined for various retail gas stations. The tanks in these trucks, which can typically hold up to 10,000 gallons, usually have several compartments, enabling them to transport different grades of gasoline or petroleum products. The truck tank is where the special additive packages of gasoline retailers get blended into the gasoline to differentiate one brand from anot
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