Life Cycle Assessment studies on lightweight materials for automotive applications - An overview

Lightweight materials have the potential to reduce vehicle fuel consumption and emissions. This study critically reviews Life Cycle Assessment (LCA) studies focused on lightweight materials (Advanced and High-Strength Steels (A/HSS), Aluminium (Al), Magnesium (Mg), and composites) for automotive chassis and body-in-white components, to identify the materials with the lowest environmental impacts, trends and improvement opportunities. Since most impacts are associated with the vehicle use-stage (due to fossil fuel consumption), lightweight materials have environmental benefits in a cradle-to-grave approach. Greenhouse gas (GHG) emissions and energy consumption are the most reported impact categories. Several studies simplify their inventory and overuse assumptions, which lead to higher results uncertainty. In addition, the primary and secondary mass reductions, recycling rates and driven distances have been identified as crucial hotspots. A/HSS is identified as the most preferable lightweight material, followed by Al. However, there is a lack of scientific consensus. To formulate sound conclusions, this review recommends that future studies should present clearer inventory data, GHG break-even driving distances, uncertainty and/or sensitivity analysis, as well as consider secondary mass reductions and assess other impact categories to unveil more hotspots for improvements. When substantial technology change is assumed, consequential LCA should be used to assess the predictive market uptake.