Assessing Lightweight Materials for Automobiles |
Problem/Opportunity
Reducing the curb weight of automobiles can significantly increase fuel economy. Decreased petroleum consumption, in turn, will improve the nation's balance of trade, increase jobs and gross domestic product, and reduce the environmental impact of fuel combustion and production. The use of lightweight materials allows automakers to decrease the weight of an automobile without decreasing its size. Advances in lightweight materials, coupled with design improvements and improved joining technology, will help assure that crashworthiness and handling characteristics in lighter cars are the same as in heavier automobiles. The part of the automobile with the greatest opportunity for weight reduction is the body itself. The competition among materials developers - primarily makers of steel, aluminum, and polymer matrix composites (PMC) - is fierce. Therefore, a program to evaluate lightweight materials that is based on independent analysis and has clear program objectives and a well-thought-out implementation plan is critical to ensure that R&D dollars are used effectively.
Approach
Argonne's Center for Transportation Research is helping the DOE determine the potential benefits of a lightweight materials program. By using a macroeconomic model developed by Argonne researchers, impacts of lightweight vehicle production on Gross Domestic Product, jobs, and balance of trade are estimated.
Aluminum and other lightweight materials have a significant role to play in improving the performance and fuel economy of passenger cars and trucks. Argonne is evaluating an all-aluminum car body for Ford Motor Co.
Argonne's approach is to estimate the vehicle life-cycle and determine the vehicle's energy, environmental, and economic impacts, assuming that aluminum and PMC materials are used extensively in the body. First, the weight, materials composition, and fuel economy of a baseline steel vehicle are delineated. Next, from an extensive literature search and interviews, aluminum-intensive and PMC-intensive vehicles are characterized. The costs of the lightweight vehicles are assumed to differ from those of the baseline steel vehicle because of the additional cost of the materials themselves. Next, a vehicle-choice model is used to simulate the competition between lightweight and conventional vehicles and to determine the vehicle mix. From total vehicle sales projections and vehicle fuel economy estimates, total fuel consumption is estimated. Embodied energy in the materials is estimated from an extensive Argonne database of materials production and recycling energy consumption. Estimated changes in total energy use are plotted over time. From fuel consumption data, changes in greenhouse gas emissions and criteria pollutants are also plotted.
Results
Preliminary results indicate that lightweight materials (such as aluminum and high-performance PMCs) have the potential to boost the fuel economy of vehicles, making it feasible for manufacturers to increase their corporate average fuel economy, even when larger vehicles are in demand. By using aluminum, significant life-cycle energy savings are projected in the 2010-2030 period, assuming an incremental cost of no more than about $800 to $1,200 per vehicle, but realizing these savings will require improvements in forming, joining, and recycling technologies. Very high cost is an impediment to the market penetration of high-performance PMC-intensive vehicles. A breakthrough in manufacturing processes and low-cost polymer synthesis is required. The product mix and pricing strategies are important. For example, the replacement of conventional-material automobiles with more expensive lightweight versions, prompting buyers to shift to light trucks and vans, would hurt overall fleet fuel economy.
Future Plans
Argonne researchers are completing the analysis, and results will be available in mid-summer 1995. Plans call for the analysis to be expanded to include other lightweight materials and engines.
Principal Investigators: |
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