Comparative assessment of environmental impacts of 1st generation (corn feedstock) and 3rd generation (carbon dioxide feedstock) PHA production pathways using life cycle assessment.

Polyhydroxyalkanoates (PHA) are bio-based and biodegradable alternatives to conventional plastic types and have the potential to reduce the environmental impacts along the life cycle. In comparison to already established production routes for PHA (heterotrophic production) based on renewable feedstock like glucose (first generation feedstock), novel production routes, such as the photoautotrophic production of PHA based on CO as feedstock (third generation feedstock) could offer new perspectives with regard to the reduction in the environmental impacts. To quantify the environmental impacts of PHA produced via photoautotrophic and heterotrophic production pathways, life cycle assessment (LCA) methodology based on ISO 14040/44 was applied, thus conducting a first of its kind comparative study for PHA based on third generation feedstock. The results show that the photoautotrophic production of PHA has advantages in comparison to heterotrophic PHA based on glucose originating from corn as feedstock in all the assessed environmental impact categories, thus showing the environmental potential of novel production routes for bioplastics. Additionally, the results of the LCA show that the chloroform-based extraction method, commonly used in the downstream processes of both the technologies, has a significant contribution of environmental impacts in the production of PHA. Therefore, the reduction of chloroform loss during the extraction process can reduce its environmental impact. Our results indicate that PHA production from CO using the photoautotrophic production route is a promising technology with regard to the environmental impacts when compared to the heterotrophic production based on glucose feedstock.