Carbon footprint of monomer recycling for mixed synthetic textiles - a grave-to-gate analysis

The production of textiles is increasing globally, generating large volumes of mixed textile waste. Research on innovative ways to treat this waste is expanding but there is a lack of published environmental assessments of methods for recycling the common synthetic fibre blend of polyethylene terephthalate (PET) and elastane. We analyse glycolytic depolymerisation processes using life cycle assessment to evaluate the climate benefits in comparison to business-as-usual (BAU). Two recycling scenarios are compared - one targets both PET and elastane (scenario A), the other only recycles PET (scenario B). These scenarios were developed in a laboratory environment and then scaled up in silico. The functional unit was the treatment of 285 tonnes of PET-elastane textile waste per year. The life cycle inventory was modelled using LCA for Experts version 10.9.3.0 and ecoinvent 3.11. Using the EF3.1 factors for life cycle impact assessment, the total climate burden of the two studied scenarios was around 1600 and 2200 tonnes of CO₂-eq, respectively. This means the emissions of the recycling cases exceed their respective BAU cases by around 62 and 98% respectively. While some additional economies of scale may be possible beyond those for which we have already accounted, and there may be strategic reasons to pursue polymer independence in a deglobalizing world, this study represents a case that contradicts the idea that recycling will solve the environmental problems of fast fashion.