Algal Biorefinery to Produce High-Value Carotenoids and Bioenergy

The rising demand for biofuel and the concern about food security has brought attention to algal biofuel, which is considered third-generation biofuel. Two decades of research proved that processing microalgal biomass to fuel is not commercially viable. This opened the door for the concepts of algal biorefineries. Microalgae are subjected to exploitation for the purpose to extract metabolites to produce high-value products. Carotenoids are such metabolites with practical applications in food, feed, cosmetics, and nutraceutical industries. After extraction of a metabolite, the residual biomass is treated as waste material. But this residual biomass can be a feedstock for bioenergy. This type of biorefinery which can produce high-priced commercial products, as well as highly demanding bioenergy has the potential to address the economic constraints of commercialization of algal biofuel. In this chapter, we have focused on the importance of algal biofuel in terms of food security and the significance of natural biomolecules over synthetics for health benefits. We investigated biorefinery approaches which can produce high value products such as astaxanthin and lutein, and then biofuel production from the residual biomass. We briefly explored the algal cultivation mechanism to obtain enhanced astaxanthin and lutein, and then latest technology to extract astaxanthin and lutein. At last, we explored potential technologies of conversion of metabolites extracted residual biomass to different forms of energy.