MFERD Life Cycle Analysis Finds Aluminum Front End Materials Achieve Best Performance for Overall Energy Use and GHG Emissions

A life cycle analysis comparing automotive materials—steel, magnesium and aluminum front end parts—presented at the SAE 2010 World Congress in Detroit by the Magnesium Front End Research Development (MFERD) project found that magnesium delivers a 15% energy savings compared with steel design and aluminum yields a 20% energy savings. When looking at the total life cycle CO₂ emissions, magnesium is 12% better than steel and aluminum is 20% better.

Initiated early in 2007 to develop key enabling technologies for a lightweight magnesium front end body structure, MFERD is sponsored by Natural Resources Canada, the Chinese Ministry of Science and Technology, the United States Department of Energy and the United States Automotive Materials Partnership.

The three-year Phase I MFERD project comprises the development of enabling technologies in high-integrity casting, wrought magnesium processing, magnesium and dissimilar metal joining and corrosion; and scientific understanding in corrosion science, crash energy management, fatigue and NVH (noise, vibration, and harshness) performance. The aim of MFERD is to develop lighter structures that are equally affordable while maintaining the safety rating. The environmental aspects associated with the selection of material are captured by the LCA task.

The LCA study compared the environmental performance of the current steel design for the front end parts of a GM-Cadillac CTS with new magnesium and aluminum designs. The LCA uses the “cradle-to-grave” approach by including primary material production, semi-fabrication production, autoparts manufacturing and assembly, transportation, use phase and end-of-life processing of autoparts. This LCA study was done in compliance with international standards ISO 14040:2006 and ISO 14044:2006 [ 2 ].

While weight savings result in reductions in energy use and carbon dioxide emissions during the use of the car, the impacts of fabrication and recycling of lightweight materials are substantial in regard to steel.

The study found that large magnesium structural parts can provide environmental benefits in terms of energy use and GHG emissions vis-à-vis steel within the expected life of the car. But overall, the aluminum design is still better at achieving the breakeven distance from energy use and GHG emissions perspectives within the vehicle life.

The manufacturing of magnesium autoparts is more energy intensive than the equivalent made of steel and aluminum. This is related to the high reactivity of the magnesium. Improvements in the Pidgeon process and the use of electrolytic process can decrease the energy requirements and the associated GHG. The weight reduction of 45kg of the magnesium front end in relation to the base line scenario will lead to a fuel economy of 507 liters over the life of the car. For the aluminum design the fuel savings are of 289 liters. As the quantity of magnesium in ELV is small, the efficiency of the recycling is low. There will be an opportunity when the penetration of magnesium increase to improve the sorting of the magnesium and aluminum rich fractions.

…In order to take the leading position, improvements are required in the extraction process of magnesium and in the recycling efficiency of ELV. It is likely these lightweight material options may improve the economic viability of advanced vehicle powertrains such as hybrid, electric, and fuel cells by reducing the powertrain size while maintaining the same vehicle performance.

—Dubreuil et al.

Resources

• Alain Dubreuil, Lindita Bushi, Sujit Das, Ambalavanar Tharumarajah, Xianzheng Gong (2010) A Comparative Life Cycle Assessment of Magnesium Front End Autoparts (SAE 2010-01-0275)