Publication Details
Abstract
The rapidly growing atmospheric CO2 concentrations have made effective and efficient carbon capture, utilization and storage (CCUS) technologies evermore imperative. Biological routes that employ microalgae have shown immense potential for CO2 biofixation due to their inherent efficient photosynthesis and fast growth rates, wide environmental range and generation of high value biomass. In contrast to successful advancements made at lab scale, challenges pertaining to technology, energy, economics, and ecology have severely limited large scale industrial cultivation of microalgae for CO2 mitigation. This review proposes a critical and detailed examination of microalgal CO2 biofixation processes, cultivation technologies, industrial constraints and avenues of future work. Mechanisms of microalgal CO2 biofixation such as the Calvin-Benson-Bassham pathway, RuBisCO activity, and carbon concentrating mechanisms (CCMs) along with different open raceway ponds, photobioreactors, and combined cultivating techniques were thoroughly investigated. The review highlights the major bottlenecks such as reduction in productivity under outdoor cultivation, high energy input for the system and harvesting as well as biological security issues associated with genetically modified strains (which cause a 'bench-to-business' transition gap). A seven-pillar conceptual framework (SCALE-UP) that incorporates biological resistance, optimized cultivation, energy efficient harvesting, efficient utilization of all the generated biomass and resources and the establishment of benchmarks to measure industrial productivity, was then introduced to overcome the above-mentioned bottlenecks. Specific research strategies have been proposed for sustainable industrial application of microalgal CO2 biofixation techniques at industrial level and in economically feasible manner.