Carbon dioxide (CO 2 ) constitutes approximately two-thirds of total anthropogenic greenhouse gas emissions and therefore represents the primary target for mitigation strategies. Among the available approaches, algal-based CO 2 capture has emerged as a promising biological option due to the high photosynthetic efficiency, rapid growth rates, and capacity of microalgae to utilize concentrated CO 2 streams directly from industrial point sources. Under optimized laboratory and pilot-scale conditions, algal systems have been reported to achieve CO 2 fixation rates in the range of approximately 0.1–1.5 g CO 2 L –1 d –1 , corresponding to areal biomass productivities of roughly 10–40 g m –2 d –1 , depending on species, reactor configuration, and environmental conditions. This review critically evaluates the potential of algal-based systems for CO 2 biofixation, with particular emphasis on algal carbon assimilation mechanisms, cultivation strategies, and operational constraints relevant to large-scale deployment. Key parameters influencing CO 2 capture efficiency, including light irradiance, pH, nutrient availability, and gas–liquid mass transfer are systematically discussed. The role of algal–bacterial consortia in enhancing carbon utilization and enabling integration with wastewater treatment processes is also examined. Furthermore, the review compares open and closed cultivation systems, highlighting trade-offs among productivity, energy demand, contamination risk, and economic feasibility. While emerging approaches such as hybrid cultivation concepts and process-intensification strategies offer pathways to improve system performance, their practical implementation remains constrained by downstream processing costs and scale-up challenges. Overall, the analysis suggests that algal-based CO 2 mitigation is most effective when deployed as part of integrated biorefinery frameworks, particularly in conjunction with wastewater treatment and value-added biomass utilization—rather than as a standalone carbon sequestration solution. This integrated perspective provides a balanced assessment of the opportunities and limitations of algae-based CO 2 mitigation within sustainable climate and environmental management strategies.
Singh et al. (Mon,) studied this question.