Techno-economic feasibility assessment of integrated microalgal biorefinery for coproducing biofuel and high-value chemicals.

Microalgae are a promising feedstock for sustainable biorefinery applications due to their potential to produce high-value bioactive compounds and biofuels. However, establishing an economically feasible microalgal biorefinery process is essential for actual industrial commercialization. In this study, a multi-product biorefinery strategy aimed at maximizing resource utilization and profit generation was applied. Based on this strategy, an integrated framework was proposed to simultaneously produce biodiesel, lutein, and 2,3-butanediol (BDO) from microalgal biomass. Additionally, the economic feasibility of the process was evaluated through a techno-economic analysis (TEA). The results indicated that the unit production cost of the process incorporating solvent recycling ($8.27 kg-1) was significantly lower than that incurred without solvent recycling ($15.39 kg-1). This was attributed to the reduced operating cost resulting from solvent recycling. The designed process achieved a gross margin (GM) of 41.54%, a return on investment (ROI) of 22.57%, a payback time (PBT) of 4.43 years, an internal rate of return (IRR) of 10.29%, and a net present value (NPV) of $15.30 million. Sensitivity analysis results identified the main product selling price and microalga carbohydrate content as key factors influencing economic feasibility. Ultimately, this study quantitatively demonstrates the importance of a multi-product biorefinery strategy in microalga-based biorefinery systems and provides a scalable process design framework for future industrial application and commercialization.