Superstructure optimization for sustainable design of an algae biorefinery

In this study a superstructure of an algae biorefinery to produce added value products (pigments, omega-3, glycerol, biodiesel, biogas, and fertilizer) from microalgae is developed. From the superstructure optimization follows a cost optimal production pathway that consists of an open pond, sedimentation and flotation, flocculation/ centrifugation without a dryer, hydrothermal liquefaction, organic solvent pigment extraction, N-butanol lipid extraction, lipid production, and anaerobic digestion. The profits of the algae biorefinery depend on the types of wastewaters. 107 million Euros income can be earned annually using 0.2 million tons of influent wastewater. The total profit of an algae biorefinery that uses influent wastewater as feedstock is approximately two times higher than the wastewater of wheat straw biorefinery. 63 million Euros income can be earned annually using 0.6 million tons of influent wastewater. Furthermore, the total profits of algae biorefinery in each season are calculated by using real data of sunlight periods of the Netherlands. Summer is the best season with more than 36 and 22 million Euros profits for algae biorefineries when using influent wastewater and wastewater of wheat straw biorefinery, respectively. Calculating total profits of algae biorefinery by considering fix value for durations of sunlight has more than 30% error.