Some Projected Add-On Control Options for CO 2 Reductions at a Coal-Fired Generating Unit Kevin Johnson URS Corporation Raleigh-Durham, North Carolina NC DENR/DAQ CO 2 Workshop April 21, 2004

2 Presentation Overview u CO 2 capture issues u CO 2 capture technologies overview –Conventional amine absorption –Advanced amine absorption –Gas separation membranes –Temperature swing adsorption –Regenerable CO 2 sorbents u Development status and projected costs u Potential next steps

3 Coal-Fired CO 2 Capture Issues (1) u Chemical absorption using amines is only technique used commercially to date to capture CO 2 from flue gas. u Amine degradation via oxidation and reaction with SO 2 and other flue gas constituents. u Lower amine concentration results in larger equipment, higher solvent circulation rates, and increased energy requirements for CO 2 regeneration from the rich amine stream. u Only a few small plants (<<1000 tpd CO 2 removal, or about < MW) in commercial operation.

4 Coal-Fired CO 2 Capture Issues (2) u Conventional MEA absorption/stripping estimated to increase electricity costs by over 50%, and consume ~30% of plants output.* u Global Climate Change Initiative goals are 90% CO 2 capture and <10% increase in cost of energy services (net of any value-added benefits, e.g., EOR, CO 2 credit trading, etc.) u DOE Carbon Sequestration R&D program goal is to achieve carbon capture/geologic sequestration at an incremental cost of $10/ton CO 2 emissions avoided. * National Coal Council, R&D Needs and Deployment Issues for Coal-Related GHG Management, May * EPRI, Evaluation of Innovative Fossil Fuel Power Plants with CO 2 Removal, December 2000.

5 Advanced Amine Absorption (1) u Proprietary oxidation inhibitors, other additives, membranes, custom solvent formulations/amines, contactor designs. u Various commercial vendors pursuing process improvements: –Fluor –Praxair –Kvaerner –MHI –ABB Lummus Crest u Current cost range ~$30-40/ton CO 2. u R&D development goal ~$20/ton CO 2

6 Advanced Amine Absorption (2) u Advanced amine absorption processes hold promise for intermediate-term CO 2 capture, with incremental (i.e., not breakthrough) reductions in cost. u Critical need for large-scale pilot plant demonstration(s) on SO 2 -/NO x -laden coal-fired flue gas. u DOE Regional Sequestration Partnership program planning Phase II pilot validation tests in the time period.

7 Gas Separation Membranes u Gas-liquid or catalyzed liquid membrane separators/reactors. u Potentially used in conjunction with unique physical solvents. u Several process vendors actively involved in technology development: –Kvaerner –Carbozyme (catalyzed enzyme) –Electrocore (natural enzyme)

8 Temperature Swing Adsorption u Use of custom-designed sorbents that adsorb CO 2 at lower temperature, and then desorb CO 2 at higher temperature. u Zeolites, synthetic zeolites, activated carbon, etc. u Adsorption Research, Inc./DOE.

9 Regenerable Sorbents u Absorption step of CO 2 removal, followed by sorbent regeneration step where CO 2 is off- gassed. u Alkali- and alkaline-earth metals (e.g., K 2 CO 3 and CaO) deposited on a substrate support are focus of research experiments. u Advantages over amine-based liquid systems include no large quantities of water involved in capture step, and additional energy savings due to lower gas/solid pressure drop. u Research Triangle Institute/DOE.

10 Development Status and Projected Costs u Except for amine absorption technologies, all CO 2 capture technologies still at the laboratory, bench-scale development level. u Based on lab results, several vendors (Carbozyme, ARI) claiming projected full scale cost performances on the order of $5-15/ton CO 2. u These, and other, potential breakthrough CO 2 capture technologies warrant further investigation and research investments.

11 Potential Next Steps (1) u NC program could proactively participate in DOE Regional Sequestration Partnership (SE). –Characterize regional sources and sinks, environmental and monitoring/verification requirements, and life cycle impacts. –Pilot validation tests not until –Based on current public commitments, more economic CO 2 capture technology will not be commercially available for coal plants before the end of the decade.

12 Potential Next Steps (2) u NC could provide cost share/co-funding to CO 2 capture technology pilot field demonstration and testing. u Attempt to address conflicting motivations of voluntary GHG program elements, GHG registry program development needs, and potential CO 2 follow-up response to CSA.