| Summary: | The growing global demand for sustainable energy solutions indicates the need for biofuels to reduce dependence on fossil fuels. Microalgae have emerged as a promising biodiesel feedstock due to their minimal resource requirements, rapid growth and higher carbon fixation efficiency compared with terrestrial crops. However, challenges such as energy-intensive production at high cost and biosafety concerns currently limit large-scale implementation. Ongoing research is focused on low-cost cultivation systems, innovative reactor design, co-product utilisation and risk mitigation practices to achieve scalable and sustainable microalgae-based biodiesel. In this contribution, the main current trends in the microalgae-derived biodiesel process are presented, with emphasis on lipid extraction and transesterification. Meaningful improvements in upstream processes – cultivation methods, harvesting, and dewatering – and downstream processes, with lipid extraction, conversion, and purification are discussed. The function of alkaline and acidic homogenous and heterogeneous, chemical and enzymatic catalysts in improving transesterification effectiveness is examined. Additionally, emerging non-catalytic approaches, as with supercritical fluid technology, are highlighted for the ability to achieve 85 % yields in a single-step conversion of algal lipids to biodiesel. Finally, the genetic and biochemical engineering capacity to increase lipid productivity and metabolic efficiency for advanced fourth-generation biofuels is examined.
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