The chemical industry uses a variety of fuel sources, nearly 50% of which are used as feedstocks. The industry is the largest single consumer of natural gas (over 10% of the domestic total) and uses virtually all the liquefied petroleum gas (LPG) consumed in U.S. manufacturing. Nearly all LPG and about one fourth of natural gas are used as feedstocks. Other energy sources include byproducts produced onsite, hot water, and purchased steam. [MECS 1994]