Review on cultivation and thermochemical conversion of microalgae to fuels and chemicals: Process evaluation and knowledge gaps

Over the last decades, microalgae have gained a commendable role in the rising field of biofuel production as they do not compete with food supply, reduce greenhouse gases emission, and mitigate CO2. Specifically, thermochemical processing of microalgae yields products, which can be used both for energy and other industrial purposes, depending on the algal strain, processing method and operative conditions. Algae are converted into various high-value products, including nutraceuticals, colourants, food supplements, char, bio-crude, electricity, heat, transportation fuel, and bio-oil. Therefore, microalgae are believed to be a strategic resource for the upcoming years and their utilization is meaningful for many industrial sectors. In this framework, this review addresses the various thermochemical processing of microalgae to various biofuels and their industrial significance. The obstacles in various thermochemical conversion methods have been critically flagged, in order to enable researchers to choose the optimal method for fuel production. Furthermore, light is shed on cultivation systems to generate rapidly microalgal biomass for thermochemical processing. Eventually, all recent literature advancements concerning microalgae cultivation and thermochemical processing are critically surveyed, and summarized.