Polyhydroxyalkanoates (PHA) production in a circular CO2 economy: it's role in mitigating global CO2 emissions
Zhiyuan Zong, Chitong Rao, C. M. Du, Rong Lü, D. Chester Upham
Abstract
• A universal carbon footprint model demonstrates that PHA production results in negative emissions. • The cradle-to-grave carbon footprint of PHA derived from waste cooking oil can be reduced to half that of fossil-based plastics. • Compared to fossil-based plastics, PHA production shows lower impacts on resources, ecosystems and human health even when green electricity is not fully available. • With a carbon tax credit, PHA production would be 11 % more cost-effective than fossil-based plastics. • 83 % of CO 2 equivalent emissions from the plastic industry can be mitigated through the use of alternative PHA combined with advanced recycling technologies. The use of fossil-fuel derived plastic significantly contributes to resource depletion and global warming. This study provides a life cycle assessment of PHA production, including (1) fully transparent in-plant data with a cradle-to-grave scope, (2) a universal life cycle model with varying input variables to ensure results are adaptable to different scenarios, (3) optimization pathways for both environmental and economic aspects, and (4) forecasts of potential impacts and compare with recycled plastic across different future timelines and locations. The cradle-to-grave carbon footprint of PHA is determined to be 5.77 kg-CO 2 e/kg-PHA today - nearly equivalent to that of conventional fossil-based plastics (5.52 kg-CO 2 e/kg-plastic) – however, with reasonable improvements projected for 2030/35, PHA would result in a carbon footprint of 2.01 kg-CO 2 e/kg-PHA. The cost is also found to be similar ($1168/t vs $1320/t).