Magnesium Life Cycle in Automotive Industry

Abstract

The transportation sector is responsible for the largest share (29% in 2019) of greenhouse gas emissions (GHG). One of the ways to reduce this share consists in introducing lightweight vehicles in order to diminish fuel consumption, and, in consequence, GHG emissions. Magnesium (Mg) carries considerable potential as a lightweight material to be used in automotive industry, e.g., in gearboxes, front end and IP beams, steering column and driver’s airbag housings, steering wheels, seat frames and fuel tank covers. Weight savings resulting from the use of Mg could reach up to 70% of the conventional parts. However, energy consumption and emissions from magnesium primary production are higher than for steel and aluminum. Therefore, enhancing magnesium recycling would be vital for ensuring its sustainable use. This study assesses the life cycle of magnesium extracted from end-of-life products. Using system dynamics modelling, we quantify the potential environmental benefits and examine aspects related to circularity of magnesium to be used in the automotive industry. Energy consumption, water use and related emissions are assessed in processes of functional (recovered Mg reused in the vehicle manufacturing processes) and non-functional (recovered Mg as an element used in aluminum alloys) recycling as well as casting and molding. Obtained results show that the implementation of circular economy strategies may help in increasing the supply of magnesium from the automotive industry up to 0.70 million tonnes (mt) in 2050. As shown by the analysis, 43% of total energy consumption and water use at the global Mg recycling stage in 2050 corresponds to non-functional casting and molding in automotive industry, followed by non-functional recycling (11%), functional casting and molding (7%) and functional recycling (2%). Also, it is estimated that the existing technologies in functional and non-functional Mg recycling in automotive industry contribute to the global warming with an emission of 5.62 and 29.66 mt of CO2 eq. in 2050, respectively.