Microalgae as a feedstock for bio-aviation fuel production: A review of techno-economic feasibility and socio-environmental impacts

As the aviation sector strives toward net-zero emissions by 2050, microalgae-derived sustainable aviation fuel (SAF) presents a promising and scalable alternative. This review provides a detailed outlook of the current techno-economic landscape and associated social and environmental trade-offs, highlighting microalgae-based aviation fuel as a viable route for aviation sector decarbonization. Nevertheless, the path to commercialization remains constrained by several challenges. Biologically, strain development with enhanced lipid yields and resilience remains limited. From a technological perspective, commercial viability is constrained by inefficient CO 2 delivery, energy and cost-intensive harvesting and dewatering, hindered lipid extraction due to resistant cell wall and challenges in catalyst stability. Economic uncertainties persist, with algal productivity, facility scale, and high budgets associated with feedstock processing and capital cost. Despite the identified socio-environmental benefits, addressing critical trade-offs requires social life cycle assessments that adequately capture localized environmental burdens, as well as the impact on host communities and product-level effects on workers and society. This review recommends key actionable priorities to accelerate commercialization. These include advancing integrated biorefineries leveraging wastewater cultivation, nutrient recycling, and high-value co-product valorization, alongside systematic pilot-scale demonstrations to validate laboratory innovations. Comprehensive assessment frameworks combining techno-economic analysis, life cycle assessment, and ISO aligned social life cycle assessment can guide sustainable deployment. These efforts must be coupled with cross-sector policies and production-linked incentives to rapidly close the cost gap with conventional jet fuels. This review underscores that coordinated advances in strain development, process engineering, and policy frameworks can establish microalgae-based aviation fuel as an equitable, transformative jet fuel alternative accelerating aviation's decarbonization. • Key cost drivers: CAPEX, lipid productivity, and feedstock; co-products reduce prices. • Harvesting and dewatering are the most energy-intensive; low-energy methods cut cost and emissions. • Lower emissions achievable with green hydrogen and recycled CO 2 . • Wastewater utilization recovers nutrients, reduces freshwater demand, and reduces fuel costs. • Integrated TEA-LCA-S-LCA and pilot validation of waste-fed biorefineries remain a gap.