The forest products industry consumed more than 3.1 quads of energy in 1994. This represents about 14% of domestic manufacturing energy use, making the forest products industry as a whole the third largest industrial consumer of energy, behind only petroleum and chemicals. Within the forest products industry, the pulp and paper industry (SIC 26) uses the vast majority of the energy, 2.66 quads, while the lumber and wood products industry uses only 0.491 quad. The industry has made good use of wood residues and byproducts (black liquor) and self-generates a large portion of its own energy needs. According to the 1994 Manufacturing Energy Consumption Survey (MECS), the lumber and wood products industry produced over 60% of its energy requirement by burning wood residues from tree harvesting and sawmill operations. In 1994, the pulp and paper industry self-generated about 50% of its energy needs, and the industry itself estimates this figure to be closer to 55% in 1997 [AF&PA 1997]. Nevertheless, the pulp and paper industry still spent over $6 billion for energy in 1994, roughly 3.7% of the value of shipments in that year, and remains the manufacturing sector's fourth largest consumer of fossil fuels. [MECS 1994, DOC/ASM 1996]