Defining CCS Ready: An Approach to An International Definition

Appendix B: Technology Design Options for a Capture Ready Plantnoted that the maximum SO 2 concentrations can be 10 ppm, 122 although low levels of 1–2ppm may be required for economic operation. 123This implies that commercial FGDs that remove 98–99% of SO x may not be sufficient tomake the economics of capture favourable, and additional SO x cleanup may be necessary. Ina Capture Ready plant design, the SO x removal technology will likely be more stringent thanis strictly necessary to comply with emission specifications. This will be a more expensiveunit, but will save money compared with adding an additional deep SO x removal unit whenCO 2 capture is retrofitted. Clearly, the use of low-sulfur coals is another prerequisite.Steam Requirement: Nearly 1.5 metric tons of low-pressure steam need to be extractedper metric ton of CO 2 for the capture process, which can reduce the overall powergeneration. 124 Furthermore, the loss of steam from the steam turbine implies that theturbine would be running at about 60% of design rating, which is off its efficiencyoptimum. 125 Hence, options to reduce the efficiency and capacity reductions due to theextraction of low-pressure steam are a critical part of designing a Capture Ready plant.Several options are described to achieve this, e.g., the use of throttled low-pressure turbine,a floating pressure LP turbine, or a clutched LP turbine lead to lower penalties when CO 2capture is retrofitted. 126B.1.2 Capture Ready Design Concepts for Amine ScrubbingIn this section, the characteristics of a reference power plant and three different options fora post-combustion CCS Ready power plant are described. The first two options are basedon plant designs from the IEA GHG 2007/4 report, 126 and the third is based on the CaptureReady design in the NETL Capture Ready report. 127Reference Plant: The reference plant represent a business-as-usual (BAU) case with noanticipation of future CO 2 capture controls. The plant is a nominal 600 MW supercriticalPC. Emission control options include flue gas desulfurization, selective catalytic reduction,and activated carbon injection. This plant is assumed to have four steam turbine stages: onehigh, one intermediate, and two low-pressure stages. Although no specific space and tie-insare provided in this plant, a retrofit is assumed to be reasonably possible.Option 1 (Throttle valve case): This first option represents a low-cost approach to aCapture Ready plant. Along with the minimum essential Capture Ready steps, such as122 For example, the Fluor Daniel Econamine FG process has a flue gas specification with a maximum of 10 ppm SO2content. Intergovernmental Panel on Climate Change (IPCC). (2005a). IPCC Special Report on Carbon Dioxide Capture andStorage. New York, NY: Cambridge University Press.123 Intergovernmental Panel on Climate Change (IPCC). (2005a). IPCC Special Report on Carbon Dioxide Capture andStorage. New York, NY: Cambridge University Press.124 Simbeck, D.. (2004). CO2 capture from power and fuels. Presentation at the International Petroleum IndustryEnvironmental & Conservation Association Climate Change Workshop, Baltimore, MD.125 Massachusetts Institute of Technology (MIT). (2007). The future of coal: Options for a carbon-constrained world.Cambridge, MA: Author.126 International Energy Agency Greenhouse Gas R&D Programme (IEA GHG). (2007a). CO2 capture ready plants (Reportno. 2007/4). Cheltenham, UK: Author.127 U.S. Department of Energy, National Energy Technology Laboratory (U.S. DOE-NETL). (2008b). CO2 capture ready coalpower plants (DOE/NETL Publication no. 2007/1301).23 February 2010 78