Economic feasibility of exploitation of a bioethanol by-product to obtain high-value biopolymers

By-products of bioethanol production, such as vinasse can be transformed by biotechnological processes into valuable compounds. In this work, the economic feasibility of producing poly(hydroxyalcanoate)s (PHAs) from vinasse and diverse microorganisms was studied employing a superstructure whose objective function is the maximization of the Net Present Value (NPV). The model was run employing data reported in the literature about PHAs productivities obtained by using different bacteria strains and vinasse as carbon source. Thus, comparison of different scenarios is shown from techno-economic and environmental aspects. Mathematical model estimated that PHA production cost was 2.27 - 3.02 USD and the investment resulted 9- 13 million dollars. The energy consumption was also calculated and it was 13.8 - 21 MJ/Kg PHA. The model returned NPV negative values in those scenarios with low accumulation and low yield of PHAs, indicating that benefits are not being obtained and, therefore, would not meet the expectations for an investment project. Positive NPV values were obtained, being the highest one 35.09 million dollars. Results evidenced that microorganism selection, concentration of the pretreated vinasse, and inorganic salts in the culture media would be the most relevant factors to take into account when designing a PHA production plant.