(511b) Multi-Scale Analysis for the Production of Biopolymers for the Substitution of Fossil-Based Plastics from Waste Revalorization

Over the past century, synthetic polymers from fossils, have revolutionized the materials industry due to their versatility and wide range of applications. Global production now exceeds 300 million tons annually ¹, having largely replaced traditional materials such as wood, glass, steel, and ceramics. This shift is driven by the unique properties of plastics, which have made them a key technology across numerous sectors: their low cost, ease of processing, water resistance, and durability have enabled advancements in construction, packaging, consumer goods manufacturing, automotive engineering, and medical applications, among others. Furthermore, their ability to take on various forms—ranging from films and fibers to packaging and structural components—has further expanded their utility. However, the very durability that has cemented their widespread use also presents a significant environmental challenge. Many plastic products are designed for short-term use, yet their slow biodegradation leads to persistent accumulation in the environment. While recycling is a theoretically viable mitigation strategy, its effectiveness is hindered by the need for energy-intensive processes such as washing, grinding, and reprocessing. In response to these concerns, bioplastics have emerged as a potential sustainable alternative. Although their production currently accounts for only about 1% of total plastic manufacturing ², rising oil prices and growing environmental awareness have driven renewed interest in their development, positioning them as a promising option in the transition toward more sustainable materials.

The growth rate of biopolymers has grown by 20-30%, with a potential for conventional plastics substitution by these materials of up to 90% ³. Among the main biopolymers, starch-derived polymers and PHB have great potential to replace most fossil-based-plastics such as polyolefins (e.g. LDPE, HDPE, LLPE, PP) or other types of polymers such as PET, PVC and PUR ². To evaluate the real potential for replacing fossil plastics, a multiscale analysis is performed including process synthesis, scale up and supply chain conceptual design for the production of starch-based biopolymers and PHB from wastes. The production network is based on two different types of biorefineries, one for each biopolymer to be produced. On the one hand, the biorefineries for starch-based biopolymer production employ waste sources such as sawdust, sludge, and CO₂, obtaining all the intermediates required (e.g., methanol, glycerol, starch) ⁴. CO₂ is obtained from DAC and/or MEA-based CO₂ capture methods, being supplied to the production centre by pipeline. On the other hand, PHB is synthesized from production centres which employ lignocellulosic biomass as raw material such as residues from the maintenance of forestry areas, corn stover or wheat straw. From the cellulose and hemicellulose content of this biomass, glucose and xylose are extracted respectively to be provided as carbon sources for the production of PHB. The biorefineries are optimized and scaled up. Finally, the supply chain model is formulated considering linear algebraic constraints where economic, environmental and social metrics developed in this work are included to evaluate from a holistic point of view the impact due to the replacement of conventional plastics. The mixed-integer linear model (MILP) is applied to the case study of peninsular Spain to show the approach, considering as discretization level the 343 agricultural regions of the territory.

The presented methodology helps in the technological replacement of synthetic polymers from non-renewable sources by biopolymers, to be used as precursors of bioplastic materials in blending for packaging, construction, automotive or electronics applications, as well as agriculture and consumer industry. The yield of the expected substitution will be evaluated as a function of the availability of residues. The framework will also provide guidelines for policy making such as subsidies or incentives required.

Acknowledgments

This work was supported by funding to José Enrique Roldán San Antonio under the call for predoctoral contracts USAL 2021, co-funded by Banco Santander. This work was supported by project PID2023-146231OB-I00 of the Spanish Government.

References

(1) Plastics Europe. Plastics - the Facts 2022; 2022.

(2) Lackner, M. Bioplastics. Kirk‐Othmer Encycl. Chem. Technol. 2000, 1–41. https://doi.org/10.1002/0471238961.koe00006.

(3) ICIS. Bioplastics projects set to prosper. https://www.icis.com/explore/resources/news/2011/06/22/9471602/bioplast….

(4) Roldán-San Antonio, J. E.; Martín, M. Optimal Integrated Plant for Biodegradable Polymer Production. ACS Sustain. Chem. Eng. 2023, 11 (6), 2172–2185. https://doi.org/10.1021/acssuschemeng.2c05356.