Third-generation biorefineries: a sustainable platform for food, clean energy, and nutraceuticals production

Sustainable transformation of biomass into a wide range of valuable chemicals, fuels, and materials is the eventual goal of a biorefinery. Algal feedstock (microalgae and macroalgae) is a principal component of third-generation (3G) biorefinery empowering the bio-renewables industry. While first-generation (1G) biorefineries are commercially viable, products (fuels and commodity chemicals) from second-generation (2G) and 3G biorefinery are not yet commercially competitive due to the gross technical challenges, scalable and production cost issues. Because of the inherently diversified nature of feedstock used in 3G biorefineries, a myriad of specific bioproducts can be produced. Furthermore, stable food/feed supply, environmental concerns, climate change, and geopolitical issues have necessitated the exploration of 3G feedstocks into fuels and renewable chemicals. Considerable success has been seen in research laboratories in the last two or three decades which led to mature technical developments in algal biomass conversion. However, the scale-up issues are still posing a big challenge for the commercial exploitation of algal feedstock into fuels and chemicals. Nevertheless, various products such as nutraceuticals, pharmaceuticals, and cosmetics are successfully being produced from algal feedstock. This review paper describes the technical developments, industrial scenario, environmental issues, and range of diversified products from 3G biorefineries. Specially, we focus on the exploration of algal biomass into fuels and biochemicals via multidisciplinary technological routes.