Comparative life cycle assessment study on cyanobacteria and maize as feedstock for polylactic acid

The move towards a bioeconomy requires to overcome the lack of biomass and to develop new processes for the production of chemicals and materials. Cyanobacteria can play a key role in the bioeconomy due to their fast growth and year-round production possibilities. In this study the life cycle assessment approach is applied in order to address three goals: (i) to evaluate the potential of cyanobacterial biomass as a replacement of maize as feedstock for polylactic acid; (ii) to identify the drivers of the environmental impacts; (iii) to assess three different improvement scenarios. Results show that cyanobacteria are currently not environmentally competitive with maize. The high electricity demand, the carbon dioxide requirements as well as urea are identified as crucial factor for the environmental impacts of cyanobacterial biomass. Replacing the electricity mix by wind power, reducing the carbon dioxide supply as well as upscaling of the lab-scale system reduces the environmental burden considerably. Further research is however necessary to optimize the production chain and to use biomass residues for valuable co-products.