The U.S. Geological Survey estimated the quantity of aluminum stocks in use in the United States to be 142 million metric tons as of 2002. Stocks in use include the aluminum in airplanes, automobiles, bridges, buildings, household appliances, machinery, and many other applications and exclude aluminum in solid-waste facilities. Continuous use of aluminum through recycling, remanufacturing, and reuse allows stocks in use to be considered a resource in place.
Table 1: Aluminum content of automobiles built in the United States, averaged for selected model years.
|Auto weight and aluminum content||1970||1975||1980||1985||1990||1995||2000||2001||2004|
|Average CW, in pounds||3,620||3,730||2,870||2,870||2,910||3,050||3,130||3,150||3,240|
Average aluminum content per vehicle,
Average alumium content per vehicle, as a
percentage of average CW
CW, curb weight of automobile.
Sources: National Highway Traffic Safety Administration, 2005b;
Naidu S. Madhu, Ducker Research Company, oral and written commun., April 5, 2005
U.S. Department of the Interior;
U.S. Geological Survey Fact Sheet 2005-3145; January 2005
This Fact Sheet compares all aluminum stocks in use with the aluminum contained in automobile stocks in use in the United States. Automobiles in use in the United States include domestic and imported passenger cars, sport utility vehicles (SUVs), trucks, light trucks, vans, and minivans in commercial (taxicabs and limousines), government, and private use. Data on vehicles with an average vehicle curb weight greater than 8,500 pounds are not included in the Fact Sheet. The curb weight (CW) is the total weight of a vehicle without passengers or cargo.
Aluminum has a unique combination of properties, including strength, light weight, crash-energy absorption, corrosion resistance, and high thermal and electrical conductivity; these qualities are highly valued by the automotive industry. Approximately 60 percent of the aluminum used in making new automobiles comes from recycled aluminum. Approximately 90 percent of aluminum contained in retired automobiles is recovered and recycled.
|Table 2: Automobiles in use and aluminum stocks in use in automobiles and all applications in the United States, averaged for selected years|
|Autos and aluminum stocks||
|Automobiles in use, in millions of units||90.6||98.1||120||140||157||179||193||213||217|
Average aluminum content per vehicle in
use, in pounds
Aluminum stocks contained within
automobiles in use, in Mt
|All aluminum stocks in use, in Mt||22.4||40.2||55.9||72.1||86.4||100||115||135||139|
Aluminum stocks contained within auto-
mobiles in use, as a percentage of all
aluminum stocks in use
Mt, million metric tons; each metric ton equals 2,204.6 pounds.
Sources: Ward’s Communication, 1982, p. 121; 1987, p. 147; 2002, p. 227; J.F. Lemons, Jr., U.S. Bureau of Mines, written commun., 1989; Davis, 1997, p. 3–7; Davis and Diegel, 2004, p. 3–5; Sullivan, 2005; D.A. Kramer, U.S. Geological Survey, oral and written commun., January 25, 2005; The Polk Company, oral commun., April 4, 2005; Naidu S. Madhu, Ducker Research Company, oral and written commun., April 5, 2005
The automotive industry has a long history of aluminum use. The 1897 Clark had an aluminum crankcase, the 1903 Gordon Bennett Napier had an aluminum cylinder block, and the 1904 Lanchester had an aluminum rear-axle housing unit. Since the 1950s, automakers have added aluminum to their mass-produced vehicles. Aluminum pistons have been standard in U.S.-made automobiles since 1955; by the mid-1960s, most U.S.-made vehicles had aluminum grilles. Aluminum bumpers were introduced in the early 1970s, and aluminum intake manifolds, in 1977. In the 1980s and 1990s, automakers used improved aluminum bumper reinforcements and suspension parts, drive shafts, engine blocks and cylinder heads, steering shafts, and wheels, along with hoods and trunk lids. Aluminum has become the metal of choice for many manufacturers of automobile body mainframes, underbody frames, and body panels. As aluminum was in competition with other automobile materials, it secured some market niches and lost others.
During the past 30 to 35 years, the use of aluminum in percentage of the average vehicle curb weight (table 1). From 1970 through 2001, the number of automobiles in use increased by more than 120 percent, and the estimated average aluminum content per vehicle increased by more than 260 percent (table 2). Figure 1 compares aluminum stocks contained in automobiles in use with all aluminum stocks in use and the average curb weight of automobiles in the United States for the years 1970 through 2001.
In 1970, the average aluminum content per vehicle was about 53.3 pounds, 98.1 million vehicles were in use, and the aluminum stocks in use within automobiles in the United States were about 2.4 million metric tons (2.4 Mt), which were about 5.9 percent of all aluminum stocks in use (40.2 Mt). During the next 31 years, the aluminum contained in automobile stocks in use increased to about 19.1 Mt, which was about 14 percent of all aluminum stocks in use (139 Mt). The average aluminum content of automobiles in use in 2001 increased to about 195 pounds per vehicle. The average CW of an automobile decreased to about 3,150 pounds in model year 2001 from 3,620 pounds in 1970.
Concerns about automobile exhaust emissions and fuel efficiency led to emission controls (Clean Air Act, enacted in 1970) and increased mileage-per-gallon standards expressed as corporate average fuel economy (CAFE) standards (Energy Policy Conservation Act, enacted in 1975). First established in 1978, fuel-efficiency requirements have been changed since then in 1979, 1980, 1981, 1985, 1986, and 1990. As CAFE and emission laws became more stringent in the late 1970s through the mid-1980s, automakers needed to improve fuel economy. This goal was achieved in part by reducing the weight of the automobile by substituting aluminum and plastics for steel.
In the 1990s, demand increased for larger vehicles such as vans, minivans, SUVs, trucks, and light trucks. To keep the increased average CW of these larger automobiles to a minimum, manufacturers used more aluminum. The average CW decreased from 3,620 pounds in model year 1970 to a low of 2,870 pounds in the early and middle 1980s and then gradually rose to 3,240 pounds in model year 2004 (table 1). The quantity of aluminum stocks within automobiles in use increased steadily from 1970 through 2001 (table 2). The trend of increasing use of aluminum in automobiles is expected to continue through the decade.
- Aluminum Association, Inc., 2001. Aluminum—The corrosion resistant automotive material. Aluminum Association, Inc., Publication AT7, 24 p. (Accessed April 22, 2005.)
- Davis, S.C., 1997. Transportation energy data book; Edition 17: Oak Ridge, Tenn., Oak Ridge National Laboratory, Center for Transportation Analysis, Energy Division, 280 p., (Accessed May 23, 2005).
- Davis, S.C., and Diegel, S.W., 2004. Transportation energy data book; Edition 24: Oak Ridge, Tenn., Oak Ridge National Laboratory, Center for Transportation Analysis, Engineering Science & Technology Division, 348 p., (Accessed December 5, 2005.)
- Lackey, Brent, 2002. The aluminum industry in Kentucky: Frankfort, Ky., Kentucky Cabinet for Economic Development, Division of Research, 29 p.
- National Highway Traffic Safety Administration, 2005a. CAFE overview—Frequently asked questions. (Accessed April 29, 2005).
- National Highway Traffic Safety Administration, 2005b. New passenger car fleet average characteristics and Historical passenger car fleet average characteristics. (Accessed December 5, 2005).
- Sullivan, D.E., 2005. Metal stocks in use in the United States: U.S. Geological Survey Fact Sheet 2005–3090, 2 p., (Accessed December 5, 2005).
- USGS, 2006. Aluminum stocks in use in automobiles in the United States. U.S. Geological Survey Fact Sheet 2005-3145.
- Ward’s Communication, 1982–2002 (selected years), Ward’s automotive yearbook: Southfield, Mich., 1982, 247 p.; 1987, 264 p.; 2002, 350 p.
Disclaimer: The U.S. Geological Survey is the original source for some content in the Encyclopedia of Earth. The U.S. Geological Survey is listed as a content source on each article that uses such content. Topic editors and authors for the Encyclopedia of Earth have edited this content and added new information. The use of information from the U.S. Geological Survey should not be construed as support for or endorsement by that organization for any new information added by Encyclopedia of Earth personnel, or for any editing of the original content.