Auto shredder residue LCA: implications of ASR composition evolution

Abstract

In this study, Life Cycle Assessment is applied to estimate potential implications of waste composition evolution in end-of-life treatments. The aim is to understand the environmental effects of treating Automotive Shredder Residue (ASR), which is the residual waste after shredding End-of-Life Vehicles (ELVs), when its composition will change as it is expected to happen in the coming years. Thus, for modeling it, two features have been mainly considered: (i) an increase in light material content such as polymers and nonferrous metals (especially aluminum) in new vehicle production, and (ii) an improved polymer separation and recycling by reducing the different kinds of plastics used in cars, according to an ecodesign-oriented strategy. Landfill, incineration, mechanical recycling, and chemical recycling scenarios have been considered as possible waste treatments for LCA analysis, and the expectations regarding the potential benefits from the recycling of aluminum and polyolefins from ELVs, for the Italian situation, have been discussed. Results confirm that innovative but still small-scale recycling plants, modeling mechanical and chemical recycling options, achieve the lowest impacts today due to the combination of material and energy recovery, with a consequent decrease in the residual amount of waste disposed of in landfill. As seen in these estimates, in terms of impact reducing benefits related to nonrenewable energy consumption and greenhouse gas emissions, ASR waste may represent an important input for secondary material production in the coming years. Also, a sustainable design of future vehicles, characterized by a reduction in the number of different materials employed and a growth of nonferrous metal use, will lead to greater economic and technical advantages for the mechanical separation activities followed by recycling processes. Lastly, the outcomes point to the need to consider both a LCA and ecodesign approaches for decision makers in waste management strategies, in order to properly handle factors which may affect future development or help organize a suitable exploitation of different treatment practices.