Algal lipids for biofuel production: strategies, environmental impacts, downstream processing and commercialization

The demand for fossil fuels has resulted in their rapid depletion and rise in the fuel costs. Moreover, fossil fuels have serious negative impacts on the environment due to their harmful emissions leading to global warming. This has paved the way for research into finding a renewable alternative to fossil fuels and exploring potential biofuel feedstocks. Biofuels are non-toxic, renewable, and have properties that are similar to conventional fuels. Among the studied feed-stocks, microalgae serve as a viable biofuel feedstock due to a number of advantages over another plant-based feed-stocks. Algal biofuels can help to restore the former green environment by completely replacing fossil fuels. However, only large-scale production and commercialization can meet these requirements. Numerous studies have been conducted to screen algal species with higher lipid yield. Despite decades of intensive research, biofuels have not reached the target of replacing conventional fuels. This is due to the challenges at every stage of its production process, starting from large-scale cultivation to commercial release of product. Novel lipid recovery strategies can be employed to tackle these limitations. For example, hybrid liquid biphasic system can be used to decrease the production costs (Yong et al. in J Water Process Eng 38: 101665, 2020). The aim of the review is to summarize the up to date research in the field of algae biofuels and to bring the focus on characterization and commercialization of algal lipids as a source of alternate energy. Furthermore, strategies to improve lipid accumulation and challenges associated with existing technologies are also discussed.