Study crushes idea for aluminum vehicle
Wednesday, May 26, 1999
Producing one ton of virgin aluminum generates approximately 10 times more carbon dioxide than the production of a ton of steel. |
A Massachusetts Institute of Technology comparison of the steel industry's UltraLight Steel Auto Body technology and the aluminum industry's aluminum-intense vehicles has found that the aluminum vehicles are not as environmentally benign as industry claims.
To make objective measurements, the MIT researchers used life cycle analysis techniques that take into account the entire range of consequences of any given technology when assessing its environmental benefits.
Compared to the UltraLight Steel Auto Body, an aluminum-intensive vehicle would require an additional 32 to 38 years of driving to offset the amount of carbon dioxide put into the atmosphere by the production of the aluminum needed to build the vehicles, according to the study.
The aluminum industry said that a one ton increase in the use of aluminum in automotive applications in place of steel would reduce carbon dioxide emissions by 20 tons over the life of an average vehicle.
The aluminum industry claims that because aluminum is lighter than steel, auto makers can use it to build lighter cars that will burn less fuel during their lifetimes and emit fewer harmful tailpipe emissions, including carbon dioxide. However, producing one ton of virgin aluminum generates approximately 10 times more carbon dioxide emissions than the production of a ton of steel.
"Typically, life cycle analyses have been oriented to use of a product, in this case, the automobile," said MIT Professor Joel Clark during a press briefing at the Annual General Meeting of the American Iron and Steel Institute. "However, the patterns of use and the distribution of emissions over a vehicle's lifetime suggest that it is important to consider the entire fleet of vehicles when examining the relative environmental merits of alternative product designs."
Unlike single product manufacture, fleet production occurs progressively. An existing fleet does not change overnight when an alternative vehicle decision is introduced. Instead, benefits are gained incrementally as each new vehicle is added to the fleet. Because of the rate of vehicle retirement in the United States, it takes more than 15 years to replace an existing automobile fleet.
The life cycle analysis study challenges the validity of the assumption that using hydroelectric power to produce large quantities of virgin aluminum will create no new CO2 emissions.
"One cannot assume that the incremental electricity requirement for production of new virgin aluminum for future use in aluminum-intensive vehicles will be hydro," said Clark. "According to Department of Energy projections, this additional electricity will be supplied by coal-fired plants, which eventually will be supplanted by gas-fired electricity generation plants."
The research also demonstrates that any improvements in powertrain efficiency and corresponding reductions in carbon dioxide emissions will lengthen the time it takes to offset aluminum's initial carbon dioxide burden.
"The MIT study strongly suggests that a large scale shift to aluminum intensive vehicles could make the CO2 problem worse — not better," said Paul Wilhelm, American Iron and Steel Institute chairman and president of U.S. Steel, who also spoke at the briefing. "This research has significant implications for our auto customers who are making decisions on materials for future generations of vehicles. Consumers who would buy an aluminum car thinking that they are helping the environment, unfortunately, would be making a mistake."
| 
ENN NEWS
