Materials Challenges and Opportunities for Enhancing the Sustainability of Automobiles
Materials play a major role in defining the sustainability performance of automobiles throughout their materials-production, manufacturing, use, and end-of-life stages. Materials production and manufacturing raise many sustainability issues, including resource scarcity and materials sourcing, energy and carbon intensity, and materials efficiency in parts fabrication. In the use stage, materials properties such as density and strength directly affect materials mass requirements, which influence two dominant sustainability parameters for vehicles: fuel economy and service life. For conventional vehicles, the operation segment of the use stage accounts for about 85% of the total life-cycle energy consumption and greenhouse-gas emissions. Consequently, powertrain technologies and efficiencies as well as fuel-cycle processes control these impacts. Future trends in vehicle electrification will shift the magnitude and distribution of life-cycle impacts and the effectiveness of materials strategies for improving sustainability, such as lightweighting. In many cases, the materials-production stage could become a greater determinant in life-cycle impacts. With current vehicle end-of-life management infrastructure, 85% of materials are recyclable, but recovery of plastics and segregation of metal alloys represent opportunities for improvement. Life-cycle assessment and cost analysis provide the most comprehensive methods for evaluating the sustainability of materials strategies. Using a life-cycle framework, this article highlights the current and future materials challenges and opportunities driving vehicle sustainability performance.