Optimization of the end-of-life tire repartition within the European treatment system to minimize its environmental impacts

This study contrasts two different approaches to inform European-scale decision-making to mitigate the environmental impacts of the end-of-life tires (ELT) management system. The first analysis is a traditional life cycle assessment (LCA) that compares the environmental performances of the 12 main available European end-of-life (EOL) technologies in ELT processing while restricting the boundaries to the EOL stage. The second analysis has a broader scope, addressing the optimization of the ELT distribution within the 12 considered pathways to minimize the environmental impacts of the total tire use in Europe under present capacity and constraints. The results of the traditional LCA show that, except for landfill, all the tested EOL routes present environmental benefits. Material recovery pathways bring the most environmental credits, whereas civil engineering pathways are the least promising. The LCA results that emerged from the optimization of ELT management technologies yield two optimal technological mixes that maximize the quantity of ELT recycled in molded objects production: such results represent a hypothetical case with no constraints. When considering constraints, that is, limitations on maximum quantities of ELT that can undergo retreading, pyrolysis, or recycling in synthetic turfs, in molded objects and in production, the number of optimal technology mixes increases to five. The type of technologies favored depends on the minimized impact categories (climate change, fossil and nuclear energy use, human health, and ecosystem quality). A comparison between constrained and unconstrained scenarios shows that achieving the best environmental performances is conditional to the accessibility of the EOL technologies as well as their individual environmental impacts.