The key to the value of crude oil is hydrocarbons, which are molecules consisting of carbon and hydrogen atoms with the carbon atoms acting as a backbone with hydrogen atoms attached to their surface. Crude oil contains hundreds of different types of hydrocarbons. The smallest hydrocarbon molecule is methane, also known as “swamp gas.” The simplest hydrocarbons are gases. When five or more hydrocarbons join together in a chain they form a liquid. More complex chains form solids like asphalt, tar, and wax.
Hydrocarbons are important to us for two reasons. First, they are filled with energy because the plants they came from stored it from sunlight. Second, they are versatile because when these molecules are linked together they form more complex, dense structures and can take on many forms. Controlling the formation of these links is the key to making a variety of marketable substances, from unleaded gasoline to jet fuel, asphalt to nylon and plastic. The first step in making these products is to separate the many different kinds of hydrocarbons found in the crude oil. This is where refineries come in.