LAUSR

Abstract Biofuel production and its research is gaining attention due to ever-increasing concerns over the depletion of fossil fuels and their devastating impact on the environment. This article reviews the various thermochemical conversion processes of biomass, focussing on microalgae. A particular emphasis of this review is the effect of experimental parameters, and feedstock pre-treatment in improving the properties of microalgae derived biofuel via torrefaction, hydrothermal liquefaction, gasification, combustion and pyrolysis processes. This review discusses the prospect and challenges of the thermochemical conversion processes of microalgae. Some of the interesting advances highlighted for further research include the co‑carbonization of microalgae with other feedstock to produce nitrogen-doped highly microporous hydrochar, the hydrothermal liquefaction of pre-treated microalgae via pulsed electric field (PEF) to decrease nitrogen contents in biocrude, and the deployment of steam as a sweep gas in the catalytic cracking of microalgae to decrease oxygenate content and enrich the hydrocarbon compounds of bio-oil.