Petroleum refining is the most energy-intensive manufacturing industry in the United States and accounts for about 7% of total U.S. energy consumption. Energy purchases from outside sources cost the industry a little over $3 billion in 1994 [MECS 1994]. This may seem low, considering that petroleum refiners are the number one energy users in manufacturing. However, a large percentage of the energy consumed in refineries is produced onsite, not purchased from outside sources. If the value of this byproduct energy were included, energy costs could be nearly $9 billion (assuming 60% of process energy is produced onsite, at a value of $3 per million Btu) [DOE 1998].

The petroleum refining industry uses energy both to supply heat and power for plant operations and as a raw material for the production of petrochemicals and other non-fuel products. According to the most recent Manufacturing Energy Consumption Survey (MECS), the U.S. petroleum refining industry consumed about 6.3 quads (quadrillion Btu, or 10¹⁵ Btu) of energy in 1994.