Flue gas CO2 supply methods for microalgae utilization: A review

Abstract

The potential for utilizing flue gas as a carbon source in microalgal cultivation holds great promise. Incorporating flue gas as a carbon source into microalgae culture processes can accelerate the growth rate of microalgae, consequently enhancing the overall economic viability of the integrated process. There are two key sources of flue gas to consider: flue gas from coal-fired power plants, characterized by a CO2 concentration of 12–15 w/w%, and flue gas from coal chemical processes, boasting a CO2 concentration of 90–99 w/w%. Additionally, the choice between an open or sealed microalgae culture system can also influence economic efficiency. Thus, there are four distinct microalgal cultivation routes to assess: in-situ open systems, off-situ open systems, in-situ sealed systems, and off-situ sealed systems. The incorporation of flue gas as a carbon source in microalgae cultivation demonstrates significant potential for reducing both environmental impact and costs, rendering it a highly promising and sustainable approach for economically efficient microalgae cultivation. In this review, the in-situ open route is recommended for the situation with high flue gas CO2 concentration and the target products of low-margin commodities, while the off-situ sealed route is suitable for the situation with low flue gas CO2 concentration and the target products of high value-added products.