Comparing the financial costs and carbon neutrality of polyester fibres produced from 100% bio-based PET, 100% recycled PET, or in combination

The rise of fast fashion has led to challenges in sustainable production and recycling of polyester textile waste. Bio-based polyethylene terephthalate (bio-PET) and the enzymatic hydrolysis of PET textiles may offer two solutions for bio and circular clothing. This study designed and simulated scaled enzymatic hydrolysis of fossil PET into ethylene glycol (r-EG) and purified terephthalic acid (r-PTA), the production of bio-EG and bio-PTA from the wheat straw ethanol (EtOH) and corn stover isobutene (IBN), respectively, and the production of PET polyester textile fibres from these monomers. The research goal was to determine whether bio-PET, r-PET, or their mixture achieves better positive profitability and NPV2023 and carbon neutrality in textile fibres. The financial returns and carbon emissions for r-PET fibres with a bio-PET content of 0%, 20%, 40%, 60%, 80% to 100% was estimated for scenario 1 (a newly constructed plant), scenario 2 (no capital costs for the EtOH or IBN processes), and scenario 3 (no capital costs for the EtOH, IBN, and enzymatic hydrolysis processes). While scenario 1 was not able to generate positive net profits or NPV2023, scenarios 2 and 3 were able to attain financial sustainability when the bio-PET content was <= 40%. On the other hand, increasing the amount of bio-PET content in the polyester fibre from 0 to 100 wt.% decreased its carbon footprint from 2.99 to 0.46 kg CO2eq./kg of PET fibre.