Practical Limitations and Considerations for Large Scale CO2 Abatement Systems

While acid gas scrubbing, including carbon dioxide (CO₂) scrubbing, technologies are mature and have been around for nearly 100 years, large scale abatement technologies have struggled to extend beyond the pilot scale with only a few notable exceptions including the Boundary Dam Power Plant in Saskatchewan and the Petra Nova Power Plant in Texas. One significant challenge of large scale post-combustion capture has been scale-up issues that are difficult to simulate using pilot plant data. For example, issues with nitrosamines, aerosols, and other pollutants that are released from these facilities at concentrations highly dependent on the chemistry of both the flue gas and absorbent are difficult to fully predict from pilot data. An alternative to scrubbing post-combustion flue gases is to remove the CO₂ directly from air. Due to the substantially lower concentration of CO₂ in air (300 ppm) compared to post combustion flue gases (about 100,000 ppm), the costs of CO₂ capture from air are largely driven by the handling and processing of massive volumes of air. These systems typically rely on a solid absorbent as passing the needed amount of gas through a liquid scrubber would be prohibitive. With any CO₂ absorption technology there will be the associated challenge of use or storage of the substantial quantity of CO₂ . As has been observed with deep injection of liquid wastes, the long-term success of sequestration technologies are difficult to validate on short time scales. This paper focuses on the practical limitations of CO₂ abatement systems both from post-combustion and direct-from-air with an emphasis on how the quality of the flue gas impacts the thermodynamics, economics, and environmental considerations for CO₂ abatement.