Gas comes from crude oil. The remains of organisms that lived on Earth hundreds of millions of years ago were eventually covered with sediment and rock. The pressure and heat of the Earth caused the remains and sediment to combine and create liquid hydrocarbon, or crude oil.
Refineries break down the hydrocarbons into many different products. The refiners do this through a distillation process. The crude oil is heated and put into a still where different hydrocarbons boil off and condense at different temperatures. The hydrocarbons are collected after condensing. Distillation is followed by additional processing. Cracking is a process that breaks down heavy hydrocarbon molecules into light hydrocarbon molecules by using heat, pressure and sometimes a catalyst. Using a catalyst increases the chemical reaction, producing more gasoline from the process.
Gasoline is the most produced product because it is the most used product. The characteristics of the end product depend on the crude oil used and the refinery’s methods. Some other popular products made from crude oil are diesel fuel, heating oil, jet fuel and liquefied petroleum gas, or LPG. A 42-gallon drum of crude oil produces 44 gallons of petroleum products. From one barrel, a refinery creates 19.7 gallons of gasoline, 10 gallons of diesel fuel or heating oil, 4 gallons of jet fuel, 1.8 gallons of heavy oil and 1.8 gallons of LPG, and the remaining 7.3 gallons is used for other petroleum products.