Production of renewable fuels and platform chemicals from carbon dioxide using microalgae: Economic and environmental perspective

Microalgae are a promising feedstock for large-scale biorefineries with integrated processes, such as cultivation, harvesting, and dewatering, to produce biochemicals and biofuels. Microalgae can absorb carbon dioxide (CO₂) and use various nutrients found in water, such as nitrates and phosphates, to increase their biomass. The production of succinic acid (SA), a cost-effective platform chemical that can be produced through anaerobic fermentation using microalgae, uses CO₂ efficiently. This study presents a techno-economic analysis (TEA) that compares Strategy A, which produces SA, ammonium sulfate (AMS), diesel blendstock (DB), and polyurethane (PU), with Strategy B, which produces SA, AMS, and DB. Process variations are also analyzed to determine their impact on succinic acid pricing. Heat integration is incorporated, which reduces heating demands by 79.8% and cooling needs by 63.8%. The economic viability of the developed process with a minimum selling price (MSP) of 2701 USD/t for SA is demonstrated, considering the market range of 2700–3710 USD/t, Furthermore, cradle-to-gate life-cycle assessment is used to evaluate the environmental impacts of Strategies A and B in comparison to the conventional fossil-fuel-based SA market. Strategy A was found to exhibit the lowest environmental impact among other succinic-acid production methods, with a low global warming potential of 0.03 kg CO₂ eq/kg SA and a negative fossil-resource consumption of −0.85 kg oil eq/kg SA.