Outdoor cultivation of microalgae in a coal-fired power plant for conversion of flue gas CO2 into microalgal direct combustion fuels

Abstract

Microalgae have piqued renewed interest as a sustainable biofuel feedstock owing to their high CO 2 conversion efficiency. However, the major limitation of microalga-based biofuel production is low productivity. In this study, CO 2 in flue gas emitted from the coal-fired power plants was fixed through mass microalgal cultivation using only sunlight as an energy source. To minimize the cost and energy required to supply the flue gas and efficiently utilize the microalgal biomass, a polycarbonate (PC) greenhouse and polymeric photobioreactors were installed near the power plant stack. Four different microalgal strains (Chlamydomonas reinhardtii, Chlorella sorokiniana, Neochloris oleoabundans, and Neochloris oleoabundans #13) were subjected to semi-continuous culturing for 1 month. The maximum biomass productivity was achieved by the N. oleoabundans #13 strain (0.703 g L −1 day −1). Additionally, polymerase chain reaction analysis revealed that the individual microalgal culture was not cross-contaminated with other microalgal cultures in this cultivation system, owing to the structural properties of photobioreactor comprising individual modules. The lipid content and calorific productivity of N. oleoabundans #13 biomass were 45.70% and 3.553 kJ L −1 day −1 , respectively, which indicate satisfactory performance of biomass as a direct combustion fuel. The CO 2 fixation rate, which was calculated based on the carbon content in the biomass, was 0.309 g CO 2 L −1 day −1. Therefore, large amounts of CO 2 can be reduced using the large-scale microalgal cultivation system, which enables efficient biological CO 2 conversion and maximizes microalgal biomass utilization.

Augmented CO2 tolerance by expressing a single H+-pump enables microalgal valorization of industrial flue gas

“…3c ), in the presence of actual coal-fired flue gas discharged from the Taean thermal power station complex unit 5 boiler of Korea Western Power Co., Ltd. The gas stream consisted of approximately 13% CO 2 , 20 ppm NO X , and 32 ppm SO X on average (vol.%) 46 . In this outdoor cultivation, coal-fired flue gas was chosen as the exemplary industrial flue gas because the discharge of CO 2 from the exhaust is the largest contributor to global emissions, and its reduction is therefore vital 47 .…”

Advances in the biological fixation of carbon dioxide by microalgae

“…was richer in total lipid content and had a higher consumption rate CO 2 than Chlorella sp . As shown in Table 1, many of our unfamiliar microalgae have excellent capabilities in both CO 2 fixation and biomass productivity 44–58 …”

Optimizing Microalgal Biomass Feedstock Selection for Nanocatalytic Conversion Into Biofuel Clean Energy, Using Fuzzy Multi-Criteria Decision Making Processes

“…According to (Bekirogullari et al, 2020;Juan et al, 2020;Markou. 2020;Sung et al, 2020), the most popular systems for microalgal cultivation are summarized as follows:…”