Challenges of Capturing Carbon

Contributor(s): 
June 13, 2012

Capturing CO2 and storing it underground has been proposed as a potentially major player in mitigating global climate change by reducing CO2 emissions. Thermal power plants, being the largest point source of CO2 emissions, have thus become the primary target proposed for CO2 capture and storage (CCS). However, it is often overlooked that power plants are not only the largest CO2 emitter, but also the largest fresh water consumer. This study, conducted by researchers in the Department of Engineering and Public Policy of Carnegie Mellon University, presents a thorough analysis on the additional water demand imposed by CCS in power plants, and provides guidance to address this issue. Working at the water-energy nexus, it suggests, we need a broader vision to solve the emerging challenges.

The concept of utilizing wastes as new resources promises us a sustainable development. However, is this concept applicable in reducing CO2 emission by turning it into useful products? Maybe not. Authors from the Electric Power Research Institute present two challenges of CO2 capture: the massive scale of CO2 emissions and the theoretical minimal energy requirement of separation. Time has come when chemists, process engineers, and power plant operators should come together to develop new post-combustion CO2 capture strategies.

Either the organic substance or the salt content in the water could be turned into energy, with the help of membranes. This review paper presents several state-of-the-art membrane technologies: pressure-retarded osmosis and reverse electrodialysis, as well as microbial fuel-cell technology, all of which aim to harness power from natural and waste waters. Reverse engineering of traditional separation processes has shed light on sustainable power generation.

References

Rubin, Edward S. and Haibo Zhai. “The Cost of Carbon Capture and Storage for Natural Gas Combined Cycle Power Plants.” Environmental Science and Technology 46(6), 3076-3084. 

Logan, Bruce E. and Menachem Elimelech. “Membrane-based processes for sustainable power generation using water.” Nature 488, 313–319. 16 August 2012.

Bhown, Abhoyjit S. and Brice Freeman. “Analysis and Status of Post-Combustion Carbon Dioxide Capture Technologies.” Environmental Science and Technology 2011 45(20), 8624-8632. September 12, 2011.