Advancements in algae-based biocrude upgrading and green hydrogen integration for sustainable aviation fuel production: a comprehensive review

Abstract

The increasing demand for sustainable aviation fuel (SAF) is driving the development of integrated pathways for renewable fuel production. Algae-based biocrude produced through hydrothermal liquefaction (HTL) represents a promising route due to the high productivity of microalgae, flexible feedstock utilization, and minimal competition with food resources. This review provides an integrated perspective on algae-HTL-to-SAF pathways by explicitly linking renewable hydrogen supply, fuel upgrading performance, and Techno-economic analysis/Life cycle assessment (TEA/LCA) assumptions across the value chain. This review critically evaluates recent advances in algal cultivation, HTL-based biocrude production, catalytic upgrading, and hydrogen-assisted hydroprocessing for converting algal biocrude into aviation-range fuels. Particular emphasis is placed on the role of green hydrogen, examining how renewable-energy-driven hydrogen production can be integrated into hydrotreatment processes to enhance deoxygenation, denitrogenation, and overall fuel quality. TEA and LCA of algae-to-SAF pathways are also evaluated, highlighting strategies to reduce production costs, lower carbon intensity, and improve life-cycle performance. In addition, the potential for on-site hydrogen generation within algae biorefineries is discussed as a means to increase process efficiency and strengthen supply-chain resilience. By addressing the full value chain from algal cultivation to hydrogen-enabled upgrading, this review provides a comprehensive assessment of recent advances in algal biocrude upgrading and green hydrogen integration for SAF production.