PHA biocomposites from lignocellulose: scalability and sustainability analyses through dynamic simulation, LCA, and TEA

Abstract

Lignocellulosic residues are underutilized carbon resources for circular, inherently carbon-negative biopolymer manufacturing. This study presents the first integrated dynamic simulation, life cycle assessment, and techno-economic analysis (DS–LCA–TEA) of polyhydroxyalkanoate (PHA) biocomposite production from lignocellulose. A kinetic and mass transfer-based bioreactor model was developed and calibrated using experimental data for Cupriavidus necator cultivated on lignocellulose-derived sugars, reproducing transient biomass and intracellular PHA accumulation (0.55 w/w PHA/substrate and 0.67 w/w PHA per cell dry weight). Dynamic outputs informed plant-wide mass and energy balances for a PHA-biocomposite process, integrating biomass pretreatment, fermentation, natural deep eutectic solvent-based PHA recovery, fiber-PHA compounding, and end-of-life circularity. The LCA results show a global warming potential (GWP) of 1.51 kg CO₂e per kg PHA. Displacing fossil-derived polypropylene yields an estimated 2.18 kg CO₂e per kg or 60% reduction in GWP, with global potential savings of ∼340 million tonnes CO₂e per y under 2030 polypropylene demand. Monte Carlo uncertainty analysis confirms a low probability (<4%) of exceeding the GWP of fossil-based-equivalent polypropylene. TEA shows the PHA biocomposite production cost of $2.6 per kg and an economic margin of $4.4 per kg for a production capacity of 1 ktpa. The discounted cash flow analysis shows a production capacity of at least 0.3 ktpa PHA biocomposite for an acceptable payback of <10 years. This work establishes lignocellulosic PHA biocomposites as a scalable, climate-friendly platform material and highlights the centrality of process integration to achieve economic feasibility.