1 MEMORANDUM TO: Docket ID No. EPA-HQ-OAR-2002-0058 FROM: Jim Eddinger, U.S. Environmental Protection Agency, OAQPS DATE: January 3, 2011 SUBJECT: Development of Alternate Equivale nt Output-Based Emission Limits for Boilers and Process Heaters located at Major Source Facilities

The purpose of this memorandum is to presen t the methodology used and results for the development of alternate output-based emission limits that are equivalent to the maximum achievable control technology (MACT) floor determ inations for boilers and process heaters at major sources of hazardous air pollutants (HAP ) reported in the memorandum “Revised MACT Floor Analysis (2011) for the Industrial, Comm ercial, and Institutional Boilers and Process Heaters National Emission Standards for H azardous Air Pollutants – Major Source.” 1 The development of the alternate equivale nt output-based emission limits followed a four-step process: First, a lis t of the best performing units for each subcategory was compiled. Next, the steam energy output for each best perfor ming unit was determined. Third, for all units reporting steam energy output data, the boiler effi ciencies were averaged and assigned as a subcategory-specific boiler efficiency factor. Finally, we then applied the average boiler efficiency factor to the final MACT limits that are in the current format of pound per million Btu heat input to develop the a lternate output-based limits. We investigated ways to promote energy effi ciency in boilers by changing the manner in which we regulate flue gas emissions. In an effo rt to promote energy efficiency in industrial, commercial, and institutional (ICI) steam genera ting facilities, we have developed alternate2 output-based emission limits, which are equivalent to the final MACT Floor emission limits that are in either the heat-input format or concentration. Traditionally, boiler emissions have been cont rolled on the basis of boiler input energy (lb of pollutant/million Btu heat input). However, input-based limitations allow units with low operating efficiency to emit more emissions per output (steam or electricity) produced than more efficient units. Considering two units of equa l capacity, under current regulations, the less efficient unit will emit more emissions because it us es more fuel to produce the same amount of output (steam or electricity). One way to regu late mass emissions and boiler efficiency is to express the emission standard in terms of output energy. Thus, output-based emission standards would provide a regulatory incentive to enhance unit operating efficiency and reduce emissions. The output-based format selected for the altern ate standards is mass of pollutant emitted per boiler steam output (lb/million Btu steam output). The objective of an output-based standard is to establish an emission limit in a format that incorporates the effects of boiler efficiency. Additionally, the limit should be in a format that is practical to implement. Thus, the format selected must satisfy the following: (1) provide flexibility in promotion of boiler efficiency; (2) permit measurement of parameters related to stack emissions and boiler efficiency, on a contin uous basis; and (3) be suitable for equitable application on a variety of facility configuratio ns. The format of lb/million Btu steam output accounts meets all three criteria . A second output-based format option considered was pound per Megawatt-hour (lb/MWh) which accounts not only for boiler effi ciency but also the turbine cycle efficiency. Although some ICI boilers generate, or cogenera te, electricity, the majority of ICI boilers produce steam only for process operati on or heating. Howeve r, the boiler’s total energy output can include both electrical and ther mal (process steam) outputs. Both of these3 energy outputs are relatively easy to measure accura tely, and currently are measured routinely in power plants. Based on this analysis, an em ission limit format based on mass of pollutant emissions per steam energy output is selected for the alternate out put-based standards. Emission limits based on this format can be applied equitably on a variety of facility configurations. Because steam output is the main energy output at al l ICI facilities, it is de sirable to use a format in “lb/million Btu steam.” Compliance with the alternat e output-based emission limits may require continuous measurement of boiler operating parameters asso ciated with the mass rate of emissions and energy outputs. Instrumentation already exists in facilities to conduct th ese measurements since the instrumentation is required to support normal facility opera tion. Consequently, compliance with the alternate output-based emission limits is not expected to re quire any additional instrumentation. However, additional signal inpu t wiring and programming is expected to be required to convert the above measurements into the compliance format (lb/million Btu steam). Since the June 4, 2010 proposal, we conducted an effort to obtain steam data (flow, temperature, and pressure) for the test period corresponding to the reported emission data from the best performing units comprising the proposed MACT floor pool. In determining alternate equivalent output-based emission limits, we fi rst determined for each of the best performing units the Btu output of the steam and then calculat ed the boiler efficiency for each of the boilers having available steam/heat input data. Boiler effi ciency is defined as steam Btu output divided by fuel Btu input. Next, we determined the aver age boiler efficiency factor for each subcategory from the best performing units in that subcat egory. We then applied the average boiler efficiency factor to the final MACT Floor (lb/ million Btu heat input) limits to develop the alternate output-based limits. The efficiency factor approa ch was selected because the4 alternative of converting all the reported data in the database to an output-basis would require extensive data gathering and an alyses. Applying an average bo iler efficiency factor, based on the individual boiler efficiency of the best performing units, woul d essentially convert the heat input-based limits to output-based emission limits. We have concluded that including alternate output-based emission limits in the final rule would not lessen the stringency of the MACT fl oor limits and would provide flexibility in compliance and cost and energy savings to owners and operators. We also recognize that we must ensure that the alternate em ission limits can be implemented and enforced, will be clear to sources, and most importantly, will be no less stri ngent than implementation of the MACT floor limits. The first step of the boiler efficiency fact or development process involved developing a list of the best performing units reported in the MACT Floor Me mo, prepared for the proposed rule, and determining the steam energy output for each of the best performing units. Appendix A presents the list of the best pe rforming units along with the available steam output information. As part of the Information Collection Reque st (ICR), both the questionnaire (ICR phase 1) and the testing phase (ICR phase 2) requested as part of the emission data submittal both heat input and steam flow during the te st. However, in order to determine steam energy output (BTU per hour), the steam conditions (tem perature and pressure) are need ed in addition to steam flow information (1000 pounds per hour). We first review ed the available test reports for steam data information. However, very few reported the st eam temperature and pressure. Therefore, we sent an email, under our ICR authority, requesting steam data (flow, temperature, and pressure) from the best performing units that corresponde d to the test period of the submitted emission data. From the obtained steam data (flow, temper ature, and pressure), we calculated the steam5 energy output (million Btu of steam per hour) using Steam Tables 2 to determine the specific enthalpy (Btu per pound) at the reported steam te mperature and pressure. Appendix A presents the steam conditions, steam flow, steam energy, and the calculated boiler efficiency for each of the best performing units for which we obtained steam information. Boiler efficiency factors are specific to a certain subcategory. Ten different subcategories were targeted in this analysis, all of which are listed in Table 1 . Although we requested and obtained steam data for the best pe rforming units identified for the proposed rule, the average boiler efficiency factors in Table 1 were developed based only on those units that were also identified as best perf orming units for the final rule.

Table 1 – Subcategories and Assi gned Boiler Efficiency Factors Subcategory Average Boiler Efficiency Factor (%) Solid fuel 97.4 Pulverized Coal/Fossil Solid 102.7

Coal/Fossil Solid Stoker 106.3 Coal/Fossil Solid Fluidized Bed 112.3 Biomass/Bio-based Solid Stoker 91.1 Biomass/Bio-based Solid Fluidized Bed 80.6 Biomass/Bio-based Solid Dutch Oven 121.7 Biomass/Bio-based Solid Fuel Cell 61.0 Biomass/Bio-based Solid Suspension Burner 72.4 Liquid Fuel Units 1 94.0

Gas 2 60.1

1 Efficiency of all liquid units was estimated to be the same, regardless6 of location. To calculate an average boiler efficiency f actor for each subcategory, all available best performing unit-specific boiler effi ciency listed in Appendix A we re averaged except for the high and low values. This approach was taken because some subcategories had uncharacteristically high or low values whic h were considered outliers. Therefore, for consistency, the high and low boiler efficiency va lues were excluded from the determination of the average boiler efficiency factor for each subcategory. We determined the alternate output-based emission limits to each MACT floor emission limit by applying the average boiler efficiency for the subcategory to the values reported in the MACT Floor Memo. The alternate output-based emission limits are summarized for each subcategory in Table 2 (existing sources) and Table 3 (new sources ). The data analyzed for the average boiler efficiency factor are shown in Appendix A.

Table 2: Summary of Calculated Output-Based (MACT Floor) Limits for Existing Boilers and Process Heaters at Major Sources of HAP
Subcategory Pollutant Output-based emission limits 1. Units designed to burn solid fuel a. Particulate Matter 0.038 lb per MMBtu of steam output. b. Hydrogen Chloride 0.04 lb per MMBtu of steam output. c. Mercury 4.5E-06 lb per MMBtu of steam output. 2. Pulverized coal/fossil solid a. CO 0.14 lb per MMBtu of steam output. b. Dioxin/Furan 3.7E-12 lb per MMBtu (TEQ) of steam output. 3. Stokers designed to burn coal/fossil solid a. CO 0.25 lb per MMBtu of steam output.

b. Dioxin/Furan 2.8E-12 lb per MMBtu (TEQ) of steam output. 4. Fluidized bed units designed to burn coal/fossil solid a. CO 0.08 lb per MMBtu of steam output. b. Dioxin/Furan 1.8E-12 lb per MMBtu (TEQ) of steam7 output. 5. Stokers designed to burn biomass/bio-based solid a. CO 0.35 lb per MMBtu of steam output.

b. Dioxin/Furan 4.4E-12 lb per MMBtu (TEQ) of steam output. 6. Fluidized bed units designed to burn biomass/bio-based solid a. CO 0.28 lb per MMBtu of steam output.

b. Dioxin/Furan 1.8E-11 lb per MMBtu (TEQ) of steam output. 7. Dutch Ovens designed to burn biomass/bio-based solid a. CO 0.45 lb per MMBtu of steam output.

b. Dioxin/Furan 1.8E-10 lb per MMBtu (TEQ) of steam output. 8. Fuel cells designed to burn biomass/bio-based solid a. CO 0.34 lb per MMBtu of steam output.

b. Dioxin/Furan 3.5E-9 lb per MMBtu (TEQ) of steam output. 9. Suspension/Grate designed to burn biomass/bio-based solid a. CO 2.0 lb per MMBtu of steam output.

b. Dioxin/Furan 1.8E-10 lb per MMBtu (TEQ) of steam output. 10. Units designed to burn liquid fuel a. Particulate Matter 0.0073 lb per MMBtu of steam output. b. Hydrogen Chloride 0.0003 lb per MMBtu of steam output. c. Mercury 3.3E-06 lb per MMBtu of steam output. d. CO 0.0083 lb per MMBtu steam output. e. Dioxin/Furan 9.2E-09 lb per MMBtu (TEQ) of steam output. 11. Units designed to burn other gases a. Particulate Matter 0.026 lb per MMBtu of steam output. b. Hydrogen Chloride 0.001 lb per MMBtu of steam output. c. Mercury 7.8E-06 lb per MMBtu of steam output. d. C0 0.005 lb per MMBtu steam output. e. Dioxin/Furan 3.9E-11 lb per MMBtu (TEQ) of steam output. 12. Units designed to burn liquid fuel located in non-continental States and territories a. Particulate Matter 0.0073 lb per MMBtu of steam output. b. Hydrogen Chloride 0.0003 lb per MMBtu of steam output. c. Mercury 8.0E-07 lb per MMBtu of steam output.8 d. CO 0.13 lb per MMBtu steam output. e. Dioxin/Furan 9.2E-09 lb per MMBtu (TEQ) of steam output. Table 3: Summary of Calculated Output-Bas ed (MACT Floor) Limits for New Boilers and Process Heaters at Major Sources of HAP Subcategory Pollutant Output-based emission limits 1. Units designed to burn solid fuel a. Particulate Matter 0.0011 lb per MMBtu of steam output. b. Hydrogen Chloride 0.0021 lb per MMBtu of steam output. c. Mercury 3.4E-06 lb per MMBtu of steam output. 2. Pulverized coal/fossil solid a. CO 0.01 lb per MMBtu of steam output.

b. Dioxin/Furan 2.8E-12 lb per MMBtu (TEQ) of steam output. 3. Stokers designed to burn coal/fossil solid a. CO 0.005 lb per MMBtu of steam output.

b. Dioxin/Furan 2.8E-12 lb per MMBtu (TEQ) of steam output. 4. Fluidized bed units designed to burn coal/fossil solid a. CO 0.02 lb per MMBtu of steam output.

b. Dioxin/Furan 1.8E-12 lb per MMBtu (TEQ) of steam output. 5. Stokers designed to burn biomass/bio-based solid a. CO 0.13 lb per MMBtu of steam output.

b. Dioxin/Furan 4.4E-12 lb per MMBtu (TEQ) of steam output. 6. Fluidized bed units designed to burn biomass/bio-based solid a. CO 0.18 lb per MMBtu of steam output.

b. Dioxin/Furan 1.8E-11 lb per MMBtu (TEQ) of steam output. 7. Dutch Ovens designed to burn biomass/bio-based solid a. CO 0.45 lb per MMBtu of steam output.

b. Dioxin/Furan 1.8E-10 lb per MMBtu (TEQ) of steam output. 8. Fuel cells designed to burn biomass/bio-based solid a. CO 0.23 lb per MMBtu of steam output.9 b. Dioxin/Furan 2.86-12 lb per MMBtu (TEQ) of steam output. 8. Suspension burners designed to burn biomass/bio-based solid a. CO 0.84 lb per MMBtu of steam output.

b. Dioxin/Furan 1.8E-10 lb per MMBtu (TEQ) of steam output. 9. Units designed to burn liquid fuel a. Particulate Matter 0.001 lb per MMBtu of steam output. b. Hydrogen Chloride 0.003 lb per MMBtu of steam output. c. Mercury 0.2E-06 lb per MMBtu of steam output. d. CO 0.0026 lb per MMBtu of steam output. e. Dioxin/Furan 4.6E-12 lb per MMBtu (TEQ) of steam output. 10. Units designed to burn other gases a. Particulate Matter 0.004 lb per MMBtu of steam output. b. Hydrogen Chloride 0.003 lb per MMBtu of steam output. c. Mercury 2.0E-07 lb per MMBtu of steam output. d. CO 0.002 lb per MMBtu of steam output. e. Dioxin/Furan 4.1E-12 lb per MMBtu (TEQ) of steam output. 11. Units designed to burnliquid fuel located in noncontinental States and territories a. Particulate Matter 0.001 lb per MMBtu of steam output.
b. Hydrogen Chloride 0.003 lb per MMBtu of steam output. c. Mercury 8.0E-07 lb per MMBtu of steam output. d. CO 0.043 lb per MMBtu steam output. e. Dioxin/Furan 4.6E-12 lb per MMBtu (TEQ) of steam output.

REFERENCES
1. A. Singleton, ERG. Revised MACT Floor Analysis (2011) for the Industrial, Commercial, and Institutional Boilers and Pr ocess Heaters Nationa l Emission Standards for Hazardous Air Pollutants – Major Source. January 2011.
2. J.H. Keenan, F.G. Keyes, P.G. Hill, and J.G. Moore, Steam Tables:Thermodynamic Properties of Water Including Vapor, Liquid, and Solid Phases – English Units , 1969.10 APPENDIX A BEST PERFORMING UNITS (See Excel spreadsheet)