Microalgae Used to Fix CO2 as Valuable Biomass

The continuous rise in greenhouse gas emissions requires appropriate mitigation strategies to be developed, one of these being CO2 capture using photosynthetic microorganisms such as microalgae (including cyanobacteria). Although photosynthetic microorganisms have large advantages over the forest and other biological processes in terms of CO2 capture efficiency and velocity, also they have disadvantages related to short-term storage and the high investment cost required to install these technologies. Thus, there are currently no industrial processes based on utilizing these microorganisms. The main reason explaining that is because such processes have less capacity than is required and are not economically feasible. To solve these problems, it is necessary to integrate microalgae production with other industrial applications, such as wastewater treatment, and to valorize the produced biomass in the commodities market. Industrial scale experiences demonstrate the feasibility of producing microalgae biomass coupled with urban wastewater treatment, and the use of the biomass for agriculture applications, with other uses as sources of bioplastics and aquafeed being also reported. To achieve reliable and economically favourable processes, the technologies used to produce the biomass must be optimized. Moreover, to ensure optimal management, advanced control strategies are essential. This chapter presents the most reliable technologies for achieving large-scale sustainable microalgae processes, along with scenarios in which these technologies can reach the market. It also looks at the challenges that need to be addressed so that microalgae processes can contribute more to the global bioeconomy and be more sustainable.