Rigid bioplastics with preserved natural structures offer greater resource efficiency and costcompetitiveness

Bioplastics offer promising alternatives to fossil-based plastics, but producing rigid bioplastics—which are challenging to produce biologically—has largely relied on inefficient chemical conversions to drop-in replacements. Emerging strategies improve biomass-use efficiency by targeting alternative structures, yet their life-cycle economic and environmental impacts remain uncertain. Here, we systematically compare rigid bioplastic production routes for biobased drop-in polyethylene terephthalate (PET) via gasification, and also emerging routes to PET via 5-chloromethyl furfural (CMF), polyethylene furanoate (PEF), and polybutylene xylosediglyoxylate (PBX). All routes reduce life-cycle carbon footprints compared to fossil plastics. Interestingly, PBX, whose monomers closely resemble the original biomass structure, uses about one-eighth of the biomass and incurs about one-tenth of the cost of PET via gasification, remaining competitive with fossil PET even under a low carbon tax of 30 €/t CO2. Because molecular structure appears to strongly influence sustainability, we propose simple chemistry-based metrics to guide future bioplastic developments.