In this study, two approaches for biodiesel production from microalgae, one through a dry route (using dried microalgae) and another through a wet route (using wet microalgae), are critically assessed. Analysis suggests that although both routes yield biodiesel of similar quality, there is a considerable difference in overall energy consumption, energy-intensive steps, and size of equipments for processing the same amount of lipids. This review depicts that both routes demand significant amount of energy, i.e. up to 120 MJ per kg of biodiesel that amounts to nearly three times the energy obtained from it. Also, the cost of production for one kg of biodiesel is high, i.e. up to $25 and $12 in dry and wet route respectively. This review article aims to present comprehensively and coherently the technical aspects of these two routes and their attributes in terms of energy consumption, manufacturing cost, and capital investment. © 2021 Institution of Chemical Engineers