Technological advances in bio-crude production and lipid extraction from algae

Algae have been broadly applied as the third-generation biomass for producing liquid biofuels by various chemical and biological approaches such as fast pyrolysis and hydrothermal liquefaction (HTL). Although fast pyrolysis is a well-established conversion technology, HTL is especially effective for feedstock with high water content like algae, since water is used as the reaction medium in the HTL process. In addition, due to the high lipid contents, algae have been regarded as one of the most valuable feedstocks to produce biodiesel via lipid extraction followed by transesterification. Thus, algal biomass is a very intriguing resource to produce either bio-crude oil or biodiesel, which after upgrading could be a substitute for drop-in fuels. In this chapter, the most recent advances in the fast pyrolysis and HTL processing of algae have been thoroughly reviewed. Furthermore, the recently developed methods for lipid extraction from algae including microwave-, ultrasound- and supercritical fluid-assisted extraction approaches have been discussed. Finally, future research directions and main conclusions are provided. © 2022 selection and editorial matter, Ajay K. Dalai, Vaibhav V. Goud, Sonil Nanda and Venu Babu Borugadda; individual chapters, the contributors.