Substitution of cast iron engine components with aluminium alloys: a life cycle perspective

Environmental sustainability is nowadays one of the most important global challenges. It is common that the amount of CO2 emissions is being used as a measure of the environmental impact of vehicles. As a result, manufacturers focus on producing lightweight car components in order to minimize the weight of the vehicles and maximize the fuel economy. As a consequence, car manufacturer designers have started to favour low density materials. However, it is usually the case that the energy footprint of the materials as well as the processes involved in the manufacturing of automotive components is often not assessed. This study focuses on the validity of the claim that lightweight materials are associated with enhanced environmental sustainability by making a full assessment of the energy consumption and CO2 emissions during the manufacturing and usage stages of diesel and petrol engine blocks made of cast iron and aluminium. For this purpose, inputs from over 100 world experts from across the automotive supply chain have been taken into consideration. Our results show that the usage of lightweight materials is often associated with higher energy consumption and CO2 emissions. More specifically, the 1.6L aluminium alloy engine block examined only seems to compensate for the additional energy consumed during their manufacturing process after 200,000 km of on-the-road driving compared to the one made of cast iron. Similar trends are observed for the CO2 emissions.