HR: 09:00h
AN: B31D-05    [Abstracts]
TI: Contactor Energy Requirements for Capturing CO₂ From ambient air using NaOH determined in a pilot-scale prototype system
AU: * Stolaroff, J K
EM: infinity@cmu.edu
AF: Civil and Environmental Engineering Carnegie Mellon University, 119 Porter Hall, Pittsburgh, PA 15213-3890 United States
AU: Keith, D
EM: keith@ucalgary.ca
AF: Chemical and Petroleum Engineering University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: Lowry, G
EM: glowry@cmu.edu
AF: Civil and Environmental Engineering Carnegie Mellon University, 119 Porter Hall, Pittsburgh, PA 15213-3890 United States
AB: Systems for capturing CO₂ from ambient air for sequestration have recently been proposed (e.g. Dubey et al., 2002; Zeman and Lackner, 2004; Keith et al., 2004). Capture from ambient air has a number of structural advantages over capture from point sources; in particular it makes possible future emissions scenarios with negative net CO₂ emissions. The systems suggested use either a Ca(OH)₂ or NaOH solution to capture CO₂ and then regenerate the solution in a chemical loop. The energy requirements of such a system, however, have been hotly disputed (Herzog, 2003). The energy requirements and effectiveness of the chemical regeneration are well established as they are practiced on a large scale in the industrial kraft process used in pulp and paper production, but the energy and land use requirements of a contactor for this system are uncertain as this component of the system is not implemented industrially. In this research, we address the most controversial component of the system, the contactor, which extracts CO₂ from air into solution. A prototype contactor with a spray tower design is constructed (1m by 6m), and CO₂ absorption by a NaOH solution spray (5 l/min) is measured. The CO₂ absorption efficiency and energy requirements per unit CO₂ absorbed are calculated. The energy requirements of the contactor are found to be on the order of 10-40 kJ/mol-CO₂, which is small compared to the energy of combustion of fossil fuels, and compared with the energy required for the regeneration steps. Thus, a NaOH-based spray tower design can serve as an energy-efficient contactor for capturing CO₂ from ambient air. Dubey, M. K., Ziock, H., Rueff, G., Elliott, S., and Smith, W. S. (2002). ``Extraction of carbon dioxide from the atmosphere through engineered chemical sinkage''. ACS -- Division of Fuel Chemistry Reprints, 47(1):81--84. Herzog, H. (2003). Assessing the feasibility of capturing co2 from the air. Technical report, MIT Laboratory for Energy and the Environment. Keith, D., Ha-Duong, M., and Stolaroff, J. K. (2005). ``Climate strategy with CO₂ capture from the air.'' Climatic Change. (In press). Zeman, F. S. and Lackner, K. S. (2004). ``Capturing carbon dioxide directly from the atmosphere.'' World Resources Review, 16(157--171):62--68.
DE: 4806 Carbon cycling (0428)
SC: Biogeosciences [B]
MN: Fall Meeting 2005