Oil refineries produce intermediary byproducts during the various stages of the oil refining process. These byproducts are transferred to thermal cracking plants for further refinement into useful commercial or consumer grade products. These intermediary products are better known as methane, ethane, propane, and butane. Light hydrocarbon gases are most commonly used as fuel in heating applications and combustion motor applications. Light hydrocarbons can also be used in the composition of synthetic rubbers and commercial fertilizers.