Carbon dioxide capture and bioenergy production using biological system - A review

With the growing use of fossil fuels and industrial activity, the amount of carbon dioxide (CO2) emission is continuously increasing and is considered a primary contributor to climate change. CO2 emissions from stationary resources (coal fire, cement plants, and other industry) can be reduced by using various carbon capture and sequestration (CCS) technologies. In this article, recent advancements in various biological methods (i.e., carbonic anhydrase (CA), hydrogenation of CO2 to formate, reduction of CO2 to methane, CO2 conversion into methanol by enzyme cascade, and the role of RuBisCo enzyme) that have been reported for CO2 capture are discussed, along with their advantages and limitations. A brief overview of other physicochemical (absorption, adsorption, cryogenic, and membrane) technologies is also provided. Although biological methods are eco-friendly and can be performed under ambient conditions, these approaches are still not cost effective, as the reactions require cofactors, and the enzymes lose activity when exposed to hot flue gas and ionic liquids. Most captured CO2 is stored by mineralization using a geological and ocean storage method without providing any economic benefit. It is a question of interest as to how we can utilize CO2 and generate revenue. Utilization of CO2 as a feedstock to produce bioenergy is a possible approach. Various microbes capable of utilizing CO2 as feedstock and producing biofuels (biodiesel and bioalcohol) have been reported. These two technologies, i.e., CO2 capture and bioconversion of CO2 into bioenergy, can be integrated to develop a process that not only mitigates CO2 effects on the environment but also solves energy problems while generating revenue.