Handbook of Microalgae-Based Processes and Products: Chapter 8 - Carbon dioxide capture and utilization using microalgae

The atmospheric accumulation of greenhouse gases (GHGs) due to industrialization and human activities is considered the main cause of climate change and recognized as one of the most crucial problems humanity will face in the upcoming years. Carbon dioxide (CO2) is the most important GHG, accounting for approximately 77% of the total emissions, considering both the volume and its global warming potential, industrial activities and population growth being the major drivers of increases in CO2 emissions. Mitigation strategies that include capture and storage of CO2 by biological alternatives may reduce the impact of CO2 emissions on the environment. Within biological technologies, microalgae are a promising tool, due to the important environmental role represented by these microorganisms in the carbon cycle, carrying out approximately 50% of the total atmospheric CO2 fixation. In this sense, CO2 capture using microalgae has gained much attention since microalgae present advantages over higher plants, such as higher solar energy yield and environmental tolerance, with the possibility of converting the microalgal biomass into biofuels or producing a wide range of value-added products. This chapter presents the aspects involved in CO2 capture by microalgae comprising the photosynthetic process involved in CO2 fixation, the emission sources and physicochemical properties, the cultivation systems for CO2 capture using microalgae, and, finally, the strategies and current approaches for enhancing CO2 capture from the genetic and metabolic modifications of microalgae to the novel design of photobioreactors.