Comprehensive approach to improving life-cycle CO₂ reduction efficiency of microalgal biorefineries: A review

Along with the increase in global awareness of rising CO₂ levels, microalgae have attracted considerable interest as a promising CO₂ reduction platforms since they exhibit outstanding biomass productivity and are capable of producing numerous valuable products. At this moment, however, two major barriers, relatively low photosynthetic CO₂ fixation efficiency and necessity of carbon-intensive microalgal process, obstruct them to be practically utilized. This review suggests effective approaches to improve life-cycle CO₂ reduction of microalgal biorefinery. In order to enhance photosynthetic CO₂ fixation, strategies to augment carbon content and to increase biomass productivity should be considered. For reducing CO₂ emissions associated with the process operations, introduction of efficient process elements, designing of energy-saving process routes, reuse of waste resources and utilization of process integration can be noteworthy options. These comprehensive strategies will provide guidance for microalgal biorefineries to become a practical CO₂ reduction technology in near future.