Challenges and Perspectives on Carbon Fixation and Utilization Technologies: An Overview

ABSTRACT

This paper provides an overview of state-of-the-art carbon fixation and utilization technologies. Several carbon capture processes, such as chemical absorption and chemical looping, are reviewed and illustrated. In addition, various types of chemicals and fuels that can be produced using concentrated CO₂ (or other forms) through physical, chemical, or enhanced biological methods are presented. Among those carbon conversion methods, two promising approaches, i.e., microalgae ponds and accelerated carbonation using alkaline solid wastes, are reviewed in detail. Microalgae are fast-growing and ubiquitous photosynthetic organisms, which are rich in protein and can be converted to biodiesel fuel. They have been recognized as an alternative feedstock not only because they use CO₂ from the atmosphere but also due to their high lipid content per biomass compared to other plants. In this study, for the microalgae technologies, the principles and applications of open pond systems are discussed in terms of both technological and economic considerations. The important operation parameters affecting productivity of microalgae, including light intensity, temperature, mixing, CO₂ delivery, accumulation of dissolved oxygen, and salinity are summarized. On the other hand, accelerated carbonation technologies are an attractive and feasible approach to integrating alkaline solid waste treatment with CO₂ fixation and utilization. In this study, the performance of various carbonation processes is critically reviewed from the perspectives of process design, energy consumption, and environmental benefits. The carbonated solid product can also be used as supplementary cementitious materials in a blended cement or concrete block. Accordingly, the performance of cement pastes with carbonated product, in terms of workability and strength development, are evaluated from the cement chemistry point of view. Cement manufacturing is an energy and material intensive process, with high annual production. It is noted that, through the accelerated carbonation process, significant indirect environmental benefits can be realized.