Global Carbon Benefits of Material Substitution in Passenger Cars until 2050 and the Impact on the Steel and Aluminum Industries

摘要

Light-weighting of passenger cars using high-strength steel oraluminum is a common emissions mitigation strategy. We provide a firstestimate of the global impact of light-weighting by material substitution onGHG emissions from passenger cars and the steel and aluminum industriesuntil 2050. We develop a dynamic stock model of the global car fleet andcombine it with a dynamic MFA of the associated steel, aluminum, and energysupply industries. We propose four scenarios for substitution of conventionalsteel with high-strength steel and aluminum at different rates over the period2010−2050. We show that light-weighting of passenger cars can become a“gigaton solution”: Between 2010 and 2050, persistent light-weighting ofpassenger cars can, under optimal conditions, lead to cumulative GHGemissions savings of 9−18 gigatons CO2-eq compared to developmentbusiness-as-usual. Annual savings can be up to 1 gigaton per year. After 2030,enhanced material recycling can lead to further reductions: closed-loop metalrecycling in the automotive sector may reduce cumulative emissions by another 4−6 gigatons CO2-eq. The effectiveness ofemissions mitigation by material substitution significantly depends on how the recycling system evolves. At present, policiesfocusing on tailpipe emissions and life cycle assessments of individual cars do not consider this important effect.