Harnessing the potential of microalgae in sequestration of CO2 emissions: Removal mechanisms, optimization strategies, and bioenergy production

Abstract

The rise in anthropogenic activities increases the release of greenhouse gases, causing serious hazards to immediate environments and public health. Among the greenhouse gases, carbon dioxide contributes significantly towards massive emissions that eventually lead to global warming. As a result, decarbonization of carbon from polluted spaces (e.g., the atmosphere) is imperative. Microalgae serve as a promising, economical, sustainable, efficient, and eco-friendly bio-factory for the sequestration and conversion of CO₂ into biomass in the presence of sunlight. The microalgal CO₂ fixation efficiency depends on temperature, pH, CO₂ concentration, light intensity, and culture medium. Strategies such as random mutagenesis, targeted genetic modifications, and the use of nanoparticles, phytohormones, and artificial intelligence are employed to enhance CO₂ capture by microalgae. Microalgal biomass is a vital feedstock for the production of beneficial bioenergy, including biodiesel, biogas, bioethanol, and biohydrogen. Thus, this review focuses on the mitigation of CO₂ emissions using microalgae. In addition, it elucidates bioprocess parameters that influence CO₂ fixation as well as the technologies that can be applied for improved CO₂ capture by microalgae coupled with biofuels that are formed from microalgal biomass. Techno-economic analysis of carbon sequestration by microalgae is also discussed.