Analysis of the impact of vehicle lightweighting on recycling benefits considering life cycle energy reductions

Abstract

This study evaluates the reductions in energy consumption of vehicle lightweighting, considering the effects of the end of life vehicles (ELV) recycling. For this propose, changes in the material composition of the body in white are assessed by an inventory analysis, including the entire life of the vehicle. The production phase is evaluated considering embodied energy values; the use phase through the mass induced energy consumption; and end of life vehicle recycling considers the part reusing, material recycling, and energy recovery as possible destinations. Moreover, the use of aluminum, advanced high strength steel (AHSS), and carbon fiber reinforced plastic (CFRP) as alternative materials are compared. The Japanese vehicle market has been taken as a case study. Furthermore, the user's cost comparison is addressed as an additional assessment variable. Our results show that the effects of vehicle lightweighting on the production and end of life phase are as essential to consider as the benefits generated in its use phase. Moreover, material lightweight must be analyzed jointly with its possible recycling destination, because when the first variable is considered individually, maximum life cycle energy reduction of 23.3 MJ per kg of part to be lightweight can be expected; however, an adequate combination of both variables could almost double those benefits to 51.0 MJ, but also incorrect combinations could be counterproductive guiding to an energy consumption increment of 92.7 MJ.