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Office of Air and Radiation

October 2010

AVAILABLE AND EMERGING TECHNOLOGIES FOR REDUCING GREENHOUSE GAS EMISSIONS FROM COAL-FIRED ELECTRIC GENERATING UNITS

Available and Emerging Technologies for Reducing Greenhouse Gas Emissions from Coal-Fired Electric Generating Units

Prepared by the Sector Policies and Programs Division Office of Air Quality Planning and Standards U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711

October 2010

Table of Contents 1. Introduction .......................................................................................................................... 5 1.1 Electric Power Generation Using Coal ...................................................................... 5 2. Coal-Fired Electric Generating Units .................................................................................. 7 2.1 Coals Burned in U.S. EGUs ....................................................................................... 7 2.2 Coal Utilization in U.S. EGUs ................................................................................... 8 2.2.1 Stoker-Fired Coal Combustion ......................................................................... 9 2.2.2 Pulverized-Coal Combustion ............................................................................ 9 2.2.3 Cyclone Coal Combustion .............................................................................. 13 2.2.4 Fluidized-Bed Combustion ............................................................................. 13 2.2.5 Coal Gasification ............................................................................................ 17 2.3 GHG Emissions from Coal-Fired EGUs.................................................................. 19 2.4 Factors Impacting Coal-Fired EGU CO2 Emissions ................................................ 20 2.4.1 Impact of Coal Rank on CO2 Emissions from EGUs ..................................... 20 2.4.2 Impact of Coal-Fired EGU Efficiency on CO2 Emissions.............................. 21 2.4.3 Impact of SO2 Controls on Coal-Fired EGU CO2 Emissions ......................... 23 3. Coal-Fired EGU CO2 Control Technologies ..................................................................... 25 3.1 Coal-Fired EGU CO2 Emissions Control Approaches ............................................ 25 3.1.1 Efficiency Improvements ................................................................................ 25 3.1.2 Carbon Capture and Storage ........................................................................... 25 3.2 Efficiency Improvements for Existing Coal-fired EGU Projects ............................ 26 3.3 Efficiency Improvements for New Coal-Fired EGU Projects ................................. 27 3.3.1 Steam Cycle .................................................................................................... 27 3.3.2 Coal Drying ..................................................................................................... 32 3.3.3 Boiler Feedwater Heating & Hot-Windbox .................................................... 34 3.4 Combined Heat and Power Plant ............................................................................. 34 3.5 Oxygen Combustion ................................................................................................ 35 4. Coal-Fired EGU Technology Alternatives Analysis ......................................................... 37 4.1 Site-Specific Coal-Fired EGU Technology Alternatives Analysis Example .......... 37 4.2 EPA GHG Mitigation Database ............................................................................... 40 EPA Contact............................................................................................................................ 41 References ............................................................................................................................ 42

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List of Exhibits Exhibit 2-1. Selected characteristics of major coal ranks used for electricity generation in the United States. ....................................................................................................... 7 Exhibit 2-2. Characteristics of coal-firing configurations used for U.S. EGUs. ................... 10 Exhibit 2-2. Continued. .......................................................................................................... 11 Exhibit 2-3. Simplified schematic of a PC-fired EGU using a subcritical boiler. ................. 12 Exhibit 2-4. Simplified schematic of an atmospheric circulating fluidized-bed (CFB) boiler power plant......................................................................................................... 15 Exhibit 2-5. Simplified schematic of a pressurized fluidized-bed combustion (PFBC) power plant.................................................................................................................... 16 Exhibit 2-6. Simplified schematic of an integrated gasification combined cycle (IGCC) power plant......................................................................................................... 18 Exhibit 2-7. CO2 emission factors for coal by coal rank. ...................................................... 20 Exhibit 2-8. CO2 formation from coal-fired EGU flue gas desulfurization (FGD) processes. ............................................................................................................................ 24 Exhibit 3-1. Existing coal-fired EGU efficiency improvements reported for actual efficiency improvement projects......................................................................................... 28 Exhibit 3-2. Summary of NETL performance, cost, and CO2 emissions comparison analysis for nominal 550 MWe PC-fired EGU burning bituminous coal by steam cycle. ............................................................................................................................ 30 Exhibit 3-3. Summary of NETL performance, cost, and CO2 emissions comparison for an IGCC power plant by gasification process. ....................................................... 32 Exhibit 4-1. Supercritical PC-fired EGU and IGCC plant cost comparison Summary prepared for Consumers Energy EGU project. .................................................. 38 Exhibit 4-2. Coal-fired EGU technology alternatives cost comparison summary prepared for Consumers Energy EGU project. ....................................................................... 39

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Acronyms and Abbreviations APFBC ASTM ASME ASU BACT Btu CAA CCS CEMS CFB CH4 CO CO2 EGU EPA FBC EPRI FGD GHG H2O HRSG HHV IGCC IEA kJ kW kWh LCOE Mg MMBtu/hr MPa Advanced pressurized fluidized bed combustion American Society for Testing and Materials American Society of Mechanical Engineers Air separation unit Best Available Control Technology British thermal unit Clean Air Act Carbon capture and storage Continuous emission monitoring system Circulating fluidized bed Methane Carbon monoxide Carbon dioxide Electric generating unit U.S. Environmental Protection Agency Fluidized bed combustion Electric Power Research Institute Flue gas desulfurization Greenhouse gas Water Heat recovery steam generator Higher heating value Integrated gasification combined cycle International Energy Agency Kilojoule Kilowatt Kilowatt-hour Levelized cost of electricity Megagram Million Btu per hour Megapascal iii

MW MWe MWh MSW N2O NETL NOX O&M PC PFBC PM PRB scfm SO2 SO3 SNCR ton/day ton/yr U.S. DOE U.S. EIA

Megawatt Megawatt electrical Megawatt-hour Municipal solid waste Nitrous oxide National Energy Technology Laboratory Nitrogen oxides Operation and maintenance Pulverized coal Pressurized fluidized bed combustion Particulate matter Power River Basin Standard cubic feet per minute Sulfur dioxide Sulfur trioxide Selective noncatalytic reduction tons per day tons per year U.S. Department of Energy U.S. Energy Information Administration

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1. IntroductionThis document is one of several white papers that summarize readily available information on control techniques and measures to mitigate greenhouse gas (GHG) emissions from specific industrial sectors. These white papers are solely intended to provide basic information on GHG control technologies and reduction measures in order to assist States and local air pollution control agencies, tribal authorities, and regulated entities in implementing technologies or measures to reduce GHGs under the Clean Air Act, particularly in permitting under the prevention of significant deterioration (PSD) program and the assessment of best available control technology (BACT). These white papers do not set policy, standards or otherwise establish any binding requirements; such requirements are contained in the applicable EPA regulations and approved state implementation plans. This document provides information on control techniques and measures that are available to mitigate GHG emissions from the coal-fired electric generating sector at this time. The primary GHG emitted by the coal-fired electric generation industry is carbon dioxide (CO2), and the control technologies and measures presented in this document focus on this pollutant. While a large number of available technologies are discussed here, this paper does not necessarily represent all potentially available technologies or measures that that may be considered for any given source for the purposes of reducing its GHG emissions. For example, controls that are applied to other industrial source categories with exhaust streams similar to the cement manufacturing sector may be available through technology transfer or new technologies may be developed for use in this sector. The information presented in this document does not represent U.S. EPA endorsement of any particular control strategy. As

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