A Review of Post-combustion CO2 Capture Technologies from Coal-fired Power Plants

Reducing CO2 emissions has become a worldwide research topic. Of all the sources of CO2 emissions, power plants burning fossil fuels, especially coals, account for a very large portion. For CO2 capture from existing coal-fired power plants, post-combustion technology is thus far considered the most viable method due to its “end-of-pipe” characteristic. Chemical absorption or scrubbing process is currently the technology most likely to be implemented in the near future but rather energy-intensive. Membrane-based CO2 separation process in recent years appears to be a competitive substitution for conventional chemical absorption technology. This paper reviews the basic process designs of chemical absorption and membrane-based separation processes for CO2 capture, as well as corresponding optimization methods including optimizing operational parameters, process modifications, membrane module types and so forth. In addition, some energetic and economic estimates from other researchers for these two CO2 capture technologies are summarized. It is found that membrane-based separation process does not possess obvious advantage over MEA-based chemical absorption process at the typical 90% CO2 capture degree in terms of both energy consumption and cost. Therefore, various optimization methods have not changed the fact that CCS technology will lay more burdens on power plants unless they can get enough allowances from government. In recent years, hybrid system with the target of utilizing more than one single capture technology seems to be new direction from the perspective of capture process design. However, it still needs to be further investigated.

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