Washington, D.C. — A promising post combustion membrane technology that can separate and capture 90 percent of the carbon dioxide (CO2) from a pulverized coal plant has been successfully demonstrated and received Department of Energy (DOE) approval to advance to a larger-scale field test.
In an $18.75 million project funded by the American Recovery and Reinvestment Act of 2009, Membrane Technology and Research Inc. (MTR) and its partners tested the Polaris™ membrane system, which uses a CO2-selective polymeric membrane (micro-porous films which act as semi-permanent barriers to separate two different mediums) material and module to capture CO2 from a plant’s flue gas. Post-combustion separation and capture of CO2 is challenging due to the low pressure and diluted concentration of CO2 in the waste stream; trace impurities in the flue gas that affect removal processes; and the amount of energy required for CO2 capture and compression.
Because the Polaris membranes are 10 times more permeable to CO2 than conventional materials (reducing the membrane area required), and use a slipstream of combustion air as a sweep gas, the system has great potential for reduced energy requirements, reasonable capture costs and greater efficiencies for post-combustion capture, all important factors for retrofitting existing coal-based plants.
Demonstrating and further validating this innovative, cost-effective membrane CO2 separation process at the 1 megawatt equivalent (MWe) pilot scale is expected to be a major step toward meeting DOE’s program goals of capturing more than 90 percent of CO2 from flue gas with less than a 35 percent increase in the cost of electricity. Consequently, MTR will now begin fabricating a 1-megawatt (MW) system capable of meeting this goal from a 20-ton-per-day slipstream of coal-fired flue gas.
The 1-MW system will be tested at DOE’s National Carbon Capture Center (NCCC) in Wilsonville, Ala., beginning in 2013. The Post-Combustion Carbon Capture Center at the NCCC enables testing and integration of advanced CO2-capture technologies, at scale, using flue gas from Alabama Power’s Gaston power plant Unit 5, an 880-megawatt supercritical pulverized coal unit. Data generated in a 6-month field test of the 1-megawatt system will be used by MTR to develop a preliminary 20-megawatt full-scale commercial design in cooperation with their partners, Vectren and WorleyParsons.
In addition to MTR, other collaborators on the three-year project include the Babcock & Wilcox Company, Electric Power Research Institute, and Southern Company. Objectives of the project, part of DOE’s Clean Coal Research Program portfolio, include reducing the capital cost, footprint, and energy penalty for CO2 capture in conventional coal-fired power plants, compared to existing commercial systems.