Techno-economic framework for sustainable use of microalgae for industrial production – A bioplastics case study

Microalgae can be used as industrial feedstock for a range of products including various types of bioplastics. For sustainable use of microalgae, identification of potentially viable products and more targeted research and development guided by thorough economic viability analysis, is essential. In this study, a techno-economic framework was developed to screen the microalgae-based plastics based on their potential economic viability assessed by their algae biomass cost, to estimate the gross margins (i.e. total revenue minus total cost divided by total revenue) for the selected products, and to identify the most important parameters for optimisation. The cost of microalgae biomass production and the minimum sale price estimate for its use as polymer blends were estimated to be US$ 1.16 kg biomass −1 and US$ 1.3 kg biomass −1 (both dry weight basis) with the assumption of low-cost availability of resources. The gross margins for producing polyhydroxyalkanoates (PHA) and starch-based plastics were estimated ranging from −28.2 % to 50 % for PHA and from −13.55 % to 56.29 % for starch-based plastics depending on the biomass productivity and the polymer yields. Microalgae biomass was found to be an unviable feedstock to produce low-value drop-in bioplastics and polylactic acid (PLA), necessitating the need for co-production with higher-value products or integration with other biotechnological application of microalgae to improve the economic feasibility. Although bioplastic production has been presented as a case study, the developed framework can be used for the viability assessment of any microalgae-based products and to guide research and development to progress towards sustainable microalgae-based industry. • A framework for techno-economic analysis of microalgal products was developed. • The viability of polymers depends on productivity, yield and by-products. • PHA and starch are more viable bioplastic options than PLA as the main product. • Simultaneous optimisation of biomass productivity and product yield is required. • The use of residual biomass as by-product is important for economic viability.