Current advancements of 3G biofuel and single-cell protein production using microalgae: carbon-sequestration, photobioreactor-cultivation technology and bio-refining strategy

Energy and nutrition scarcity are significant future challenges due to growing global population, resource scarcity and climate change. Microalgae are emerging as a favorable feedstock owing to their high photosynthetic efficiency, rapid proliferation, and remarkable capacity to sequester atmospheric CO₂. Harnessing this carbon-rich biomass for the production of third-generation liquid biofuels and single cell proteins (SCP) provides a sustainable way to address both energy and nutritional demands. This review explores recent developments in cultivation methods using open and closed system photobioreactors, biomass harvesting, and conversion technologies for liquid biofuel production. Simultaneously, the potential of microalgae cells as a source of SCP is discussed with respect to its nutritional properties, digestibility, and application in food and feed sectors. The integration of biofuel and SCP production in a biorefinery model enhances resource utilization, reduces process costs, and supports circular bioeconomy goals. The review emphasizes that carbon sequestered microalgal biomass holds significant potential in achieving the dual objectives of climate change mitigation and food-energy security through sustainable biofuel and protein production. This present investigation in the form of a review can help esteemed researchers, budding entrepreneurs and profound industrialists to evaluate the impression of the microalgae-based products towards mitigating energy and food security.