The Ohio State University (OSU), along with its partners, will develop a cost-effective design and manufacturing process for novel membrane modules that efficiently captures CO2 from power plant flue gas. The innovative membrane design combines the selectivity and stability of inorganic microporous membranes and the cost and flexibility of polymer materials. This design will result in hybrid membranes with exceptionally high CO2 permeance, high selectivity of CO2 over nitrogen (N2), and the full operational stability needed for energy-efficient CO2 capture. The membranes will be implemented in a two-stage CO2 capture process with the potential to meet the DOE goals of 90 percent CO2 capture with less than a 35 percent increase in the cost of electricity (COE).
An important cost driver of current CO2 capture technologies is the parasitic power required to maintain the driving force for membrane separation. Initial OSU research found that parasitic power needs can be sufficiently reduced in a two-stage CO2 capture process. In the first stage (see Figure 1) CO2 is removed from flue gas by evacuation; in the second stage the remaining CO2 is removed using an air sweep. This process has the potential to meet DOE targets with membranes that can achieve a CO2/N2 selectivity of around 200, a permeance above 3,000 gas permeation units (GPU), and can remain stable in the presence of flue gas contaminants. This combination cannot be achieved with fully polymeric membranes. Fully inorganic microporous membranes are sufficiently selective and stable but are generally too expensive due to high manufacturing costs. Hence, the OSU design combines favorable inorganic membrane selectivity with the cost-effectiveness of polymer processing in continuous mode.
OSU will conduct bench-scale development and testing of the process for new membrane modules for CO2 capture during the three-year project. The membrane will consist of a thin selective inorganic layer embedded in a polymer structure that allows it to be manufactured in a continuous process. It will be incorporated in spiral-wound modules for bench-scale tests at actual conditions. The membranes that are developed should achieve the performance requirements by using a cost-effective nanoporous polysulfone support; depositing a very thin, highly selective yet permeable inorganic membrane; and applying a polydimethylsiloxane (PDMS) or amorphous fluoride polymer top layer for defect abatement. The multi-layer support provides strength, a smooth deposition surface, and high permeance. OSU will scale up the optimized membrane to a width of at least 14 inches and a length of at least 50 feet using their in-house continuous fabrication machine. Three pilot/prototype membrane modules will be fabricated and tested to demonstrate the membrane’s performance. Technical and economic feasibility studies will be completed, as well as an environmental, health, and safety (EH&S) assessment.
The mission of the U.S. Department of Energy/National Energy Technology Laboratory (DOE/NETL) Carbon Capture Research & Development (R&D) Program is to develop innovative environmental control technologies to enable full use of the nation’s vast coal reserves, while at the same time allowing the current fleet of coal-fired power plants to comply with existing and emerging environmental regulations. The Carbon Capture R&D Program portfolio of carbon dioxide (CO2) emissions control technologies and CO2 compression is focused on advancing technological options for new and existing coalfired power plants in the event of carbon constraints.
Pulverized coal plants burn coal in air to produce steam and comprise 99 percent of all coal-fired power plants in the United States. Carbon dioxide is present in the flue gas exhaust at atmospheric pressure and a concentration of 10–15 percent by volume. Postcombustion separation and capture of CO2 is a challenging application due to the low pressure and dilute concentration of CO2 in the waste stream, trace impurities in the flue gas that affect removal processes, and the parasitic energy cost associated with the capture and compression of CO2. Membrane-based CO2 capture technologies utilize permeable or semi-permeable materials that permit the selective separation of CO2 from flue gas. Unique membrane compositions along with innovative process designs have the potential to effectively reduce the energy penalties and costs associated with post-combustion CO2 capture for both new and existing coal-fired power plants.
The innovative membrane design combines the selectivity and stability of inorganic microporous membranes and the cost and flexibility of polymer materials to achieve a CO2 capture membrane with the high CO2 permeance and CO2/N2 selectivity that is required for viable post-combustion capture of CO2. The project is anticipated to produce a cost-effective design and manufacturing process for CO2 capture membrane modules that can contribute to achieving the DOE goal of 90 percent CO2 capture with less than a 35 percent increase in the COE.
Primary Project Goal
The project goal is to develop a cost-effective design and manufacturing process for new membrane modules to capture CO2 from power plant flue gas.
The following objectives will support the accomplishment of the project goal: (1) demonstrate that the membrane has a CO2/N2 selectivity of greater than 200 and CO2 permeance of at least 3,000 GPU in the lab; (2) demonstrate the continuous fabrication of the membrane with the described performance; and (3) demonstrate that the prototype membrane module can achieve greater than 90 percent CO2 capture of at least 95 percent pure CO2.
Complete laboratory-scale synthesis and characterization of two types of inorganic/polymer composite membranes.
Conduct a modeling study of the membrane and continuously update the model with experimental results to guide the experimental effort on the novel membrane process.
Down-select to one inorganic/polymer composite membrane for further development.
Scale up and fabricate prototype membranes using the continuous membrane fabrication machine at OSU.
Perform bench-scale synthesis and testing through two additional levels of improved performance to develop an optimal prototype membrane.
Fabricate three pilot/prototype membrane modules with high membrane packing density.
Demonstrate carbon capture with the pilot/prototype membrane modules using flue gas consisting of 13.2 percent CO2, 17.3 percent water vapor, 67.2 percent N2, and 2.3 percent oxygen, as well as 300 ppm sulfur dioxide.
Complete final technical and economic feasibility studies and an EH&S assessment.
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