Utilization of CO2 in power plant flue gas for the production of lipid and carbohydrate using microalgae

Abstract

The ever-rising demand for energy has led to the increased installation of power plants all around the globe. Power plants are the major source of CO2 emissions which has been known to cause global warming. So far, no technology that can capture and reduce all carbon dioxide emissions from power plants exists though many have been suggested. Biological fixation of CO2 has been spotlighted as one of the most promising methods for reducing atmospheric carbon dioxide accumulation. Microalgae are fast-growing microorganisms that rely on photosynthesis for growth and hence can utilize carbon dioxide. Furthermore, microalgae can convert the captured carbon dioxide into useful biochemicals such as lipids and carbohydrates. Power plant flue gases typically contain 10-15% carbon dioxide, which, if utilized by microalgae could create a carbon-neutral process. However, utilizing flue gas for the cultivation of microalgae requires certain factors to be taken into consideration. The most important of which are the toxicity of flue gas compounds on microalgae and the mass cultivation of algae to capture as much carbon dioxide as possible. Hence, this study introduces the microalga Chlorella sp. ABC-001 which meets such requirements. Effects of various abiotic conditions such as CO2 supply, nitrate concentration and pH on the biomass, lipid and carbohydrate production are analyzed. Additionally, the use of seawater for economical mass cultivation of this strain is explored. Finally, tolerance to SO2 and NO gases in flue gas is studied and the potential for flue gas cultivation is discussed.