## Standards of Performance for **Fossil**
**- Fuel** 
**- Fir** **ed Steam Generating Units for Which**  **Construction Is Commenced After**  **August 17, 1971**

**(40 CFR 60 subpart D) Standards of Performance for**  **Electric Utility Steam Generating Units for Which**  **Construction Is Commenced**  **After September 18, 1978**

**(40 CFR 60 subpart Da) Standards of Performance for**  **Industrial**
**- Commercial** 
**- Institutional Steam Generating Units** 

**(40 CFR 60 subpart Db) Standards of Performance for Small**  **Industrial**
**- Commercial** 
**- Institutional Steam Generati**  **ng Units**

**(40 CFR 60 subpart Dc)**
**Response to Public Comments on**  **Rule Amendments Proposed**  **May 3, 201 1**  **(73 FR 33642)**

US Environmental Protection Agency Office of Air Quality Planning and Standards Sector Policies and Programs Division Research Triangle Park, NC 27711

December 2011i 

### Table of Contents 1. Introduction

................................ ................................ ................................ ................................ ............................... 1 2. Response to Comments on Proposed NSPS Amendments to

................................ ................................ ................... 1 Subparts D and Da

................................ ................................ ................................ ................................ ........................ 1 2.1 General NSPS Rule Development

................................ ................................ ................................ ................... 1 2.1.1 Fuel and Technology Neutral Approach for Rule Development

................................ ........................... 1 2.1.2 Selection of Best System of Emissions Reduction (B SER)

................................ ................................ ... 3 2.1.2.1 Consideration of EGU Energy Efficiency in Selection of BSER

................................ ............... 3 2.1.2.2 Consideration of IGCC Technology in Selection of B SER

................................ ........................ 3 2.1.3 Net Energy Output Based Emissions Standards Format

................................ ................................ ........ 4 2.1.4 Standards for Reconstructed and Modified EGUs

................................ ................................ ................. 5 2.1.5 Standards for Combined Heat and Power (CHP) Unit s Subject to NSPS

................................ ............. 5 2.1.6 NSPS during Periods of EGU Startup, Shutdown, and Malfunction

................................ ..................... 6 2.1.7 Facility

- Wide Emissions Averaging

................................ ................................ ................................ ...... 6 2.1.8 Interrelationship of NSPS with other EPA Rulemakings Affecting EGUs

................................ ........... 7 2.1.8.1 Source Category Impact Analysis

................................ ................................ .............................. 7 2.1.8.2 Delay of NSPS Rulemaking until NESHAP Affe cting EGUs is Finalized

................................ 7 2.1.8.3 Proposal of EGU NSPS Amendments with EGU NESHAP

................................ ...................... 7 2.2 Rule Applicability

................................ ................................ ................................ ................................ ............ 8 2.2.1 Regulation of IGCC facilities under 40 CFR 60 subpart KKKK

................................ .......................... 8 2.2.2 Exemption of EGUs Using “Innovative Technologies”

................................ ................................ ........ 8 2.2.3 Applicability to Permitted EGUs for which Construction Has Not Commenced

................................ .. 9 2.3 Particulate Matter (PM) Emissions Standards

................................ ................................ ................................ . 9 2.3.1 Selection of BSER for PM Emissions

................................ ................................ ................................ ... 9 2.3.2 Regulation of Combined PM Emissions

................................ ................................ ................................ 9 2.3.3 Regulation of PM 2.5 Emissions

................................ ................................ ................................ ............. 11 2.3.4 Selection of PM Emissions Limit Value

................................ ................................ .............................. 11 2.3.5 PM Control Cost Analysis

................................ ................................ ................................ .................... 12 2.3.6 PM Standards Exemptions

................................ ................................ ................................ .................... 12 2.3.6.1 Opacity Standard Exemption for EGUs Using PM CEMS

................................ ....................... 12 2.3.6.2 Opacity Standard Exemption for EGUs Complying with a Combined PM Standard

............... 12 2.3.6.3 PM and Opacity Standard Exemptions for Natural Gas Fired EGUs

................................ ....... 12 2.3.6.4 PM and Opacity Standards Exemption for Low

- Sulfur Fuel Fired EGUs

................................ 13 2.4 Sulfur Dioxide (SO 2 ) Emissions Standards

................................ ................................ ................................ ... 13 2.4.1 Selection of BSER for SO 2 Emissions

................................ ................................ ................................ .. 13 2.4.2 Selection of SO 2 Emissions Limit Value

................................ ................................ .............................. 14 2.3.3 SO 2 Control Cost Analysis

................................ ................................ ................................ ................... 15ii

2.4.4 Coal Refuse

- Fired EGU Exemption from SO 2 Standards

................................ ................................ .... 15 2.5 Nitrogen Oxides (NO X) Emissions Standards

................................ ................................ ............................... 15 2.5.1 Selection of BSER for NO X Emissions

................................ ................................ ................................ 15 2.5.2 Combined NO X + CO Emissions Limit

................................ ................................ ................................ 16 2.5.3 NO X Emissions Limit

................................ ................................ ................................ ............................ 17 2.6 Compliance Requirements

................................ ................................ ................................ ............................. 18 2.6.1 Opacity Monitoring

................................ ................................ ................................ .............................. 18 2.6.2 PM Continuous Emission Monitoring

................................ ................................ ................................ .. 18 2.6.3 Electronic Reporting of Performance Test Data

................................ ................................ ................... 19 2.6.4 Monitoring PM and Opacity Emissions from EGUs Using ESPs

................................ ........................ 21 2.7 Other Proposed Amendments

................................ ................................ ................................ ........................ 21 2.7.1 Rule Definitions

................................ ................................ ................................ ................................ .... 21 2.7.1.1 Definition of “Affected Facility”

................................ ................................ .............................. 21 2.7.1. 2 Definition of “Gaseous Fuel”

................................ ................................ ................................ ... 21 2.7.1.3 Definition of “IGCC Electric Utility Steam Generating Unit”

................................ ................. 21 2.7.1.4 Definition of “Natural Gas”

................................ ................................ ................................ ...... 22 2.7.1.5 Definition of “Petroleum Coke”

................................ ................................ ............................... 22 2.7.2 General Duty

................................ ................................ ................................ ................................ ........ 23 2.7.3 Affirmative Defense Provisions

................................ ................................ ................................ ........... 23 2.7.4 Subpart Da Mercury Provisions

................................ ................................ ................................ ............ 24 2.7.5 Removal of References to 30

- Day Rolling Averages

................................ ................................ ........... 24 2.7.6 Deletion of Obsolete Provision References in Rule

................................ ................................ ............. 25 2.7.7 Proposed Rule Language Corrections and Clarifications

................................ ................................ ..... 25 3. Response to Comments on Proposed NSPS Amendments to Subparts Db and Dc

................................ ................ 26 3.1 Definition of “Distillate Oil”

................................ ................................ ................................ ................... 26 3.2 Exemption of Steam Generating Units Subject to Other NSPS

................................ ............................... 26 3.3 Applicability to Temporary Boilers

................................ ................................ ................................ ......... 26 3.4 Site

- Specific Monitoring Plan

................................ ................................ ................................ ................. 27 3.5 Opacity Monitoring

................................ ................................ ................................ ................................ . 27



### List of Tables Table 1. List of Commenters Cited in this Summary Document Submitting Comments to EPA Air and Radiation Docket Number EPA

- HQ

- OAR

- 2011

- 0044 Regarding NSPS Rule Amendments Proposed May 3, 2011 (76 FR 24976)

..... 2iii 

### Acronyms and Abbreviations BACT Best Available Control Technology BSER Best S ystem of Emission Reduction BLD Bag leak detection Btu British thermal unit CAA Clean Air Act CCS Carbon capture and storage CEMS Continuous emissions monitoring system CFB Circulating fluidized bed CHP Combined heat and power CO Carbon monoxide COMS Continuous opacity monitoring system CROMERR Cross

- Media Electronic Reporting Regulation DOE U.S. Department of Energy EGU Electric steam generating unit EPA U.S. Environmental Protection Agency ERT 

### Electronic Reporting Tool ESP Electrostatic precipitator FGD Flue gas desulfurization GHG Greenhouse gas IGCC Integrated gasification combined cycle kWh Kilowatt

-hour MW Megawatt MWC Municipal waste combustor MWh Megawatt

-hour NAAQS National Ambient Air Quality Standard NO 2 Nitrogen dioxide NO x Nitrogen oxides NSPS New Source Performance Standards NSR New Source Review OMB Office of Management and Budget PM Particulate matter PRA Paperwork Reduction Act PSD Prevention of Significant Deterioration SCR Selective catalytic reduction SNCR Selective non - catalytic reduction SIP State Implementation Plan SO 2 Sulfur dioxide SO x Sulfur oxidesIntroduction

1 

## 1. Intr**oduction**
On February 27, 2006, the United States Environmental Protection (EPA) promulgated amendments (71 FR 9866) to the new source performance standards (NSPS) for electric utility steam generating units (EGUs) under 4 0 CFR part 60 subparts D and Da

. EPA was sub sequently sued by the offices of multiple state Attorneys General and environmental organizations on the se amendments. On September 2, 2009, EPA was granted a voluntary remand without vacatur of the 2006 amendments. On May 3, 2011 , EPA proposed amendments (76 FR 24976 ) in response to the voluntary remand. These amendments included proposed new emissions limits for particulate matter (PM), sulfur dioxide (SO 2 ), and nitrogen oxides (NO X) for EGUs that commence construction, reconstruction , or modification on or after May 3, 2011. As part of this action, the Agency also propos ed several minor amendments, technical clarifications, and corrections to existing provisions applicable to the fossil fuel

fired EGU s under 40 CFR 60 subparts D and Da, as well as large and small industrial

- commercial

- institutional steam generating units NSPS under 40 CFR part 60 subparts Db and Dc. A 90

- day period ending August 4, 2011 was provided for the public to submit comments to EPA regarding the proposed subparts D, Da. Db, and Dc amendments. Approximately 200,000 comments were entered into EPA’s Air and Radiation docket assigned for this NSPS rulemaking (number 

### EPA

- HQ

- OAR

- 2011

- 0044 ) . Many of these comments were duplicative of comments submitted to EPA’s Air and Radiation do cket assigned for the development of the proposed national emission standards for hazardous air pollutant (NESHAP) from coal

- and oil

- fired EGUs under CAA section 112 (number 

### EPA

- HQ

- OAR

- 2009

- 0234 )

. EPA reviewed all of the comments entered into docket EPA

- HQ

- OAR

- 2011

- 0044 and grouped the commenters into three general categories. The first category is commenters submitting duplicative copies of comments also submitted to docket EPA

- HQ

- OAR

- 2009

- 0234 regarding the proposed NESHAP rulemaking, and which do not c ontain any comments specifically related to the proposed NSPS amendments. The second category consists of commenters stating only ge neral support or opposition to the NSPS rulemaking . Commenters supporting the amendments frequently included statements requesting that EPA establish the most stringent air emissions standards possible for EGUs. Commenters opposing the amendments frequently stated that the proposed NSPS amendments are overly stringent and burdensome and would inhibit or prevent the construction of new coal

- fired EGUs, thereby increasing costs for electricity

. The third and final category of public commenters are those providing comments regarding specific issues and topics related to the rule development and proposed rule language for amendments to 40 CFR 60 subparts D, Da, Db, and D c . This document presents a summary of the public comments entered into docket 

### EPA

- HQ

- OAR

- 2011

- 0044 regarding specific issues and topics related to the development of the proposed NSPS amendments to 40 CFR 60 subparts D, Da, Db, and D c (i.e., comments submitted by commenters in the third category) and EPA’s responses to those comments . The comment summaries pertaining to subparts D and Da are grouped by topic in Section 2 of this document

. Comments pertaining to proposed amendments specific to subparts Db and Dc are included in Section 3. Table s 1 and 2 match the commenter to the docket entry number cited in Section s 2 and 3 for specific legal or technical comments. Some of the comment sets were signed or submitted on behalf of multiple commenters.Introduction

2 **Table 1. List of Commenters Cited in this Summary Document Submitting Comments to EPA Air and** 

**Radiation Docket N umber EPA** 
**- HQ** 
**- OAR** 
**- 201**  **1**
**- 00**  **44 Regarding NSPS Rule Amendments**  **Proposed May 3, 2011**  **( 76**  **FR 24976 )** 
**EPA -**  **HQ -**  **OAR -**  **2011 -**  **0044 Document No.**  **Date Submitted Name and Affiliation**  4634 August 4, 2011 James S. Pew Earthjustice 4635 August 4, 2011 Thomas C. Perry National Mining Association 4656 August 4, 2011 William D. Bissett Kentucky Coal Association 4673 August 4, 2011 Reid T. Clemmer PPL Services Corporation 4674 August 4, 2011 Martha E. Rudolph State of Colorado Colorado Department of Public Health and Environment 4686 August 4, 2011 John T. Heard The Virginia Coal Association 4698 August 2 , 2011 Ronald A. Amirikian State of Delaware Department of Natural Resources & Environmental Control 4712 August 4, 2011 John M. McManus American Electric Power 4713 August 4, 2011 William O’Sullivan State of New Jersey Division of Environmental Protection 4714 August 4, 2011 Mark R. Vickery State of Texas Texas Commission on Environmental Quality 4715 August 4, 2011 Erika Padgett Elizabeth Wheeler Clean Wisconsin Kim Wright Midwest Environmental Advocates Peter Bakken Wisconsin Interfaith Power and Light George Meyer Wisconsin Wildlife Federation 4760 August 3, 2011 Jolene M. Thompson American Municipal Power, Inc. 4765 August 4, 2011 Alex Hofmann Theresa Pugh American Public Power Association 4766 August 4, 2011 Chris M. Hobson Southern Company 4768 August 3, 2011 James A. Landreth SCE&G 4770 August 3, 2011 Desi M. Chari The Dow Chemical Company 4830 August 4, 2011 Rae E. Cronmiller National Rural Electric Cooperative AssociationIntroduction

3 **EPA -**  **HQ -**  **OAR -**  **2011 -**  **0044 Document No.**  **Date Submitted Name and Affiliation**  4832 August 4, 2011 Kathleen L. Barrón Exelon Corporation 4833 August 4, 2011 JoAnne Rau Randal Griffin Dayton Power and Light Company 4834 August 4, 2011 Jay Hudson Santee Cooper 4836 August 4, 2011 F. William Brownell Craig S. Harrison Lauren Freeman Hunton & Williams LLP Counsel to the Utility Air Regulatory Group (UARG) 4839 August 4, 2011 Verne Shortell NRG Energy, Inc. 4841 August 4, 2011 Robert D. Bessette Council of Industrial Boiler Owners 4893 August 4, 2011 Tom Thompson, Eco Power Solutions (USA) Corp 4926 August 4, 2011 Lisa Jacobson The Business Council for Sustainable Energy 4984 August 4, 2011 Brian H. Moeck The Large Public Power Council 4985 August 4, 2011 Raymond L. Evans FirstEnergy Co rporation 4989 August 4, 2011 John M. McManus American Electric Power 4997 August 4, 2011 Les Oakes Cynthia AM Stroman King & Spalding LLP Counsel to The IPP Coalition 5000 August 4, 2011 John L. Stowell Duke Energy 5074 August 4, 2011 Dav id Gardiner Alliance for Industrial Efficiency 5075 August 4, 2011 Caroline Choi Progress Energy 5077 August 4, 2011 John W. Myers Tennessee Valley Authority 5087 August 4, 2011 Raymond L. Evans FirstEnergy 5089 August 4, 2011 Thomas C. Perry National Miming Association 5208 August 3, 2011 G. Vinson Hellwig State of Michigan Department of Environmental Quality 5195 August 4, 2011 Kerry Kelly Waste ManagementIntroduction

4 **EPA -**  **HQ -**  **OAR -**  **2011 -**  **0044 Document No.**  **Date Submitted Name and Affiliation**  5210 August 4, 2011 Susanne Brooks Elena Craft Mark MacLeod Hilary Sinnamon Mandy Warner Peter Zalzal Environmental Defense Fund 5240 August 4, 2011 Michael J. Nash Gulf Coast Lignite Coalition 5279 August 3, 2011 Eric Redman Summit Texas Clean Energy, LLC 5470 August 3, 2011 Mark J. Sadlacek Los Angeles Department of Water and Power 5477 August 15, 2011 Williw R. Taylor U.S. Department of the Interior 5715 August 4, 2011 Ann Brewster Weeks Clean Air Task Force Sanjay Narayan Sierra Club James S. Pew Earthjustice John Walke Natural Resources Defense Council Janice E. Nolen American Lung Association John Suttles Southern Environmental Law Center Joseph Mendelson III National Wildlife Federation Justin Bloom Scott Edwards Waterkeeper Alliance 5749 July 20, 2011 Myra C. Reece State of South Carolina Bureau of Air Quality, South Carolina Department of Health and Environmental Control 17620 in Docket No. EPA

– HQ

– OAR

– 2009

–0234 August 4, 2011 S. William Becker National Association of Clean Air Agencies
17622 in Docket No. EPA

– HQ

– OAR

– 2009

–0234 August 4, 2011 David Foerter Institute of Clean Air Companies
17711 in Docket No. EPA

– HQ

– OAR

– 2009

–0234 August 4, 2011 Paul Noe and Robert Glowinski American Forest & Paper Association (AF&PA) and American Wood Council (AWC) 17755 in Docket No. EPA

– HQ

– OAR

– 2009

–0234 August 3, 2011 Eddie Terrill State of Oklahoma Oklahoma Department of Environmental Quality 17852 in Docket No. EPA

– HQ

– OAR

– 2009

–0234 August 4, 2011 Gregory C. Staple American Clean Skies Foundation (ACSF)Introduction

5 **EPA -**  **HQ -**  **OAR -**  **2011 -**  **0044 Document No.**  **Date Submitted Name and Affiliation**  17878 in Docket No. EPA

– HQ

– OAR

– 2009

–0234 August 4, 2011 Ben Yamagata Coal Utilization Research Council
17929 in Docket No. EPA

– HQ

– OAR

– 2009

–0234 August 4, 2011 James S. Pew Earthjustice
17975 in Docket No. EPA

– HQ

– OAR

– 2009

–0234 August 4, 2011 Environmental Integrity Project Eric SchaefferResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

1 

## 2. Response to Comments on Pr**oposed NSPS Amendments to** 

**Subparts D and Da 2.1 General**  **NSPS Rule Development 2.1.1 Fuel and Technology Neutral Approach for**  **Rule Development Comment:**  One commenter (4698) stated support for EPA decision to adopt a fuel and technology neutral approach to developing the NSPS for new EGUs because it potentially f acilitates the selection of a cleaner fuel as part of the overall integrated emissions compliance strategy, and provides flexibility in the design, construction, and operation of the unit in a configuration optimized for a given EGU. One commenter (5210) s tated that “fuel neutral” standards should be based on the cleanest burning fuels instead of EGUs that burn pulverized coal, which EPA has used as the basis for the proposed emissions limits. According to the commenter, this approach violates the intent of Congress under Clean Air Act (CAA) section 111 that NSPS for new sources be forward looking and technology forcing. 

### Many commenters (4766, 4830, 4834, 4948, 5077 , 17878 

### ) oppose using a fuel and technology

neutral approach to developing NSPS for EGUs, and instead recommend developing standards based on technology that account for the type of fuel burned. One commenter (4766) stated that 

### EPA has no basis for developing “fuel neutral” standards in which all coal

- , gas - , and oil

- fired EGUs are subject to identical NSPS emissions limits. This approach unlawfully fails to consider the differences among boilers using different fuel types. Congress gave EPA the authority to “distinguish among classes, types, and sizes” when establishing standards; EPA, therefore, has an obligation to explain how it is applying the CAA Section 111 criteria to each fuel type, and to explain the national policy implications of its choices. A third commenter (4830) stated that it is bad public policy for NSPS to effectively eliminate whole categories of generation ty

pes, pollution control devices, and fuels. Diversities in generation design are critical to optimizing a facility for its specific and intended use. For example, fluidized bed combustion (FBC) is an ideal technological choice for intermediate

- sized generation, and can utilize a broad array of fuels, from biomass to coal of different ranks. On the other hand, pulverized coal (PC) units have generally less fuel flexibility but are better suited for larger generation uses and can be designed to have superior thermal efficiency . An NSPS that effectively precludes coal, a particular coal rank, or combustion design is in effect tailoring the nation’s future options for electric generation. CAA Section 111 statutory provisions are directed at disseminating best system of emission reduction ( BSER) throughout an identified source category and not for the purposes of significantly narrowing the nation’s choices for types of steam electric generation and fuel to power it. **Response:** The vast majority of subpart Da affected facilities burn coal as the primary fuel. Itis within EPA ’s authority under the CAA to establish fuel and technology neutral standards . (See, for example , Lignite Energy Council v. EPA) It is also within EPA’s auth ority to subcategorize standards based on fuel and boiler type

. Whichever approach EPA chooses, it is appropriate for it to establish standards for EGUs that allow the use of inherently cleaner burning fuels to comply with the standards. The amended NO X and PM standards for EGUs are largely fuel neutral, since the achievable emissions rate for the best system of emission reduction ( BSER) is similar across boiler and fuel types. While the amended SO 2 standard does not establish separate standards based on co al rank, it does account for the impact of fuels with inherently high sulfur concentrations on the performance of the BSER technology by providing an alternate percent reduction standard

. EPA has concluded that the amended standards allow affected EGUs the flexibility to use the boiler design and fuel types that best meet the site

- specific needs of the EGU owner and operator. All of the amended standards have been achieved by primary boiler types (pulverized coal and fluidized beds) and across all coal ranks. Under the adopted fuel neutral approach, owners/operators of affected EGUs have the flexibility to build new units designed to use a cleaner burning fuel as an alternative to installing post

- combustion emission control technology or to co

- fire cleaner burning fuels with coal and install slightly less

- efficient post combustion control technology.Response to Comments on Proposed NSPS Amendments to Subparts D and Da

2 Neither natural gas nor distillate oil is typically used in new baseload steam generating units (e.g., boilers). B asing the standard s on either of these fuels would result in standards that are not economically achievable for a coal

fired EGU. EPA has concluded that it is appropriate to continue to allow the construction of properly controlled coal

- fired baseload EGU since, as a general matter, it is not economi cally feasible to burn either natural gas or distillate oil in a baseload boiler/steam turbine EGU. Basing the standards on what is achievable by BSER employed on a coal

- fired unit accomplishes this. EPA has concluded that the use of natural gas and distillate oil will still play a significant role in the future generation of electricity. Rather than burning natural gas or distillate oil in a boiler based EGU, however, any new baseload electric generation based on the use of either of these fuels woul d likely use combined cycle combustion turbines. C ombustion turbines burning natural gas and distillate oil generate power more efficiently and economically tha n a boiler burning natural gas or distillate oil . The efficiency and capital cost benefits of co mbined cycle facilities outweigh the fact that natural gas and distillate oil are significantly more expensive per unit heat input than coal. **Comment:** Several commenters (4836, 4997) stated that IGCC technology is inherently different from other coal

base d electric generation technologies and should be regulated separately. The NSPS applicable to IGCC EGUs should address the unique characteristics of IGCC technology

. Factors that should be examined to properly consider the design and operational characteri stics of IGCC technology include: 1) operating scenarios in which the IGCC EGUs (combustion turbines and duct burner) are combusting different fuels or a combination of fuels , such as natural gas, coal or other carbonaceous compound (pet roleum coke, biomas s, municipal solid waste, etc.) , derived syngas, and/or syngas produced off

- site; 2) the applicability of any work practice and fuel sampling provisions as they relate to the design and operation of IGCC EGU s; and 3) the use of heat input and generation output terminology specific to IGCC EGUs. **Response:** EPA has concluded that the language is sufficiently clear that the output from an IGCC facility is the combination of the output from the combustion turbine, steam turbine, and any useful thermal output. T he heat input to an IGCC facility is the combined heat input to the combustion turbine engine and any fuel input to the duct burners in the heat recovery steam generator. For an IGCC facility that does not coproduce hydrogen or carbon containing chemicals , this value should be close to the energy content of the raw coal input to the gasification system (greater than 95%). The gasification/purification system should be designed to provide a uniform syngas regardless of the feedstock so it is unclear how the feedstck would impact emissions. The commenter did not provide data indicating that the use of natural gas during periods when the gasification system is not providing syngas would create compliance problems . On the contrary, combined cycle facilities woul d only need to maintain a NO X emissions rate of 25 ppm to comply with the amended NOX standard. This emissions rate is routinely achieved by both combustion turbines using dry low NO X com bustion controls and natural gas

- fired diffusion flame combustion tur bines using water or steam injection. The combustion of natural gas also results in minimal SO 2 and PM. P ost combustion controls would not even be required to maintain compliance with the emission standards. **Comment:** One commenter (5210) stated that high thermal efficiency should be used to establish standards, instead of being considered a control technology. In EPA’s current proposed amendments to the NSPS, there is no discussion of thermal efficiency or what efficiency rate was used by the Agency to determine the new standards. The commenter requests that EPA explain in the final rule what thermal efficiency assumptions were used in determining the new NSPS, and whether they are different from the assumptions use d in the last amendments. The commenter al so recommends that EPA use the greatest feasible thermal efficiency for EGUs as an input to determine the NSPS

. **Response:** T he facilities used to establish the output

-based standards included some of the most thermal efficient facilities . Therefore, the emission standards account for both high thermal efficiency and the efficiency of the emissions control equipment. T his is the preferred approach when sufficient data is available , and simultaneously accounts for both the thermal efficiency and control equipment efficiency under various operating conditions. We consequently concluded it is not necessary to measure emissions on a heat input basis and then use an assumed efficiency to convert to an output

-based standard , but rather directly established out put

-based standards based on the performance of the best performing facilities

.Response to Comments on Proposed NSPS Amendments to Subparts D and Da

3 **Comment:** One commenter (5240) stated that separate NSPS must be established for the subcategory of EGUs burning coal with a heat input of less than 8,300 Btu/lb as was the case in EPA’s proposed NESHAP standards. According to the commenter, emissions of air pollutants, especially PM and SO 2 , are significantly different when burning these types of coal and must be reflected in any applicable NSPS. **Response:** The commenter provided no data indicating a subcategory for low Btu fuel such as lignite would be appropriate based on emissions data, or that SO 2 and PM controls would not work as effectively with other types of coal. Fabrics filters, the selected BSER f or control of PM emissi ons, are designed to control emissions to a specified outlet concentration and are relatively independent of the PM concentration coming into the baghouse. The SO 2 standard has an alternate percent reduction requirement that specifically accounts for the use of high sulfur fuels. In addition, various coal cleaning, upgrading, and drying technologies for low rank coals reduce the ash, sulfur, and moisture content of these coals resulting in a fuel with characteristics similar to that of higher rank coals. Finally, owners/operators have a choice on what fuel to burn and could co

- fire cleaner fuels as a compliance option. The following are several examples of existing facilities and their emissions data (which demonstrate that the current standards are achievab le for low rank coals): 1. The Sandow 5B facility is a subcritical lignite

- fired fluidized bed EGU and is presently operating below the amended SO 2 % reduction alternative. Furthermore, both Sandow 5A and 5B are operating below the amended PM standard of 0.090 lb/MWh. 2. The Oak Grove 1 and 2 facilities are supercritical lignite

- fired pulverized coal EGUS. Both are presently operating below the amended numerical SO 2 standard, and the Oak Grove 2 facility is also operating below the amended SO 2 % reductio n requirement. 3. The Milton R. Young B1 and B2 facilities are subcritical lignite

- fired cyclone boiler EGUs. Both are operating below the amended PM standard of 0.090 lb/MWh. 

## 2.1.2 Selection of Best **System of Emission Reduction (** **BSER )**  **2.1.2. 1**  **Consideration of EGU Energy Efficiency in Selection of**  **BSER Comment:**  One commenter (4634) stated that EPA ’s failure to set NSPS emissions limits for PM, SO 2 , and NO X reflecting the use of energy

- efficient design is unlawful and arbitrary. New coal

- fired E GUs can significantly reduce emissions of all pollution emitted by incorporating energy

- efficient design (e.g., use of supercritical boilers), allowing them to produce more electricity from burning a given amount of coal. To satisfy the directives o f CAA s ection 111, EPA must assume a higher efficiency in combination with emissions controls to impose more stringent emissions limits for PM, SO 2 and NO X . Another c ommenter ( 17929 ) questions EPA basing the proposed output

-based emission s limit s on gross electrical generating efficiency of 36 percent, which is not BSER as required by the CAA. The commenter states that 25 percent of existing EGUs achieve this generating effic iency, or higher and new EGUs can achieve net efficiencies as high as 45 percent. **R esponse:**  Efficiency has already been accounted for since the facilities used to establish the amended standards include some of the highest efficiency supercritical facilities. The comment from commenter 17929 is unclear and appears to refer to the appro ach taken in previous amendments to subpart Da. The analysis in this rulemaking did not assume any gross efficiency. 

### 2.1.2.2 **Consideration of IGCC Technology in Selection of**  **BSER Comment:**  One commenter ( 5715 ) stated that integrated gasification combined cycle ( IGCC ) technology is a demonstrated system of emission s control for EGUs and EPA should consider it in determining BSER to control PM, SO 2 and NO X emissions from coal

- fired EGUs

. Another commenter ( 4997 ) stated that integrated gasification IGCC technology is a power generation technology and should not be identified as EGU emissions control. **Response:** As stated in the preamble, the benefits resulting from reduced emissions of criteria pollutants are not sufficient in all instances to justify the higher capital costs of today's IGCC units.Response to Comments on Proposed NSPS Amendments to Subparts D and Da

4 

## 2.1.3 Net E **nergy Output Based Emissions Standards Format**  **Comment:** Comments were received in support of and in opposition to EPA ’s proposal to require affected EGUs to mee t the proposed NSPS for PM, SO 2 , and NO X using an emissions standards format that expresses limits as the allowable amount of pollutant emitted per net energy output by the affected EGU. Several c ommenters ( 5715, 5074, 5210 ) supporting the proposal stated that use of this format will encourage improvements in overall EGU facility energy efficiency , which results in lower air pollutant emissions and 

### is an incentive to minimize parasitic energy demands from pollution control equipment ( auxiliary energy demand s is synonymous with parasitic energy demands)

. Many o ther commenters (4673, 4698, 4712, 4765, 4830, 4836, 4989, 4997, 5000, 5077, 5089, 5208, 17878 ) oppose the mandatory use of this format , stating that the NSPS should be based on limits on the allowable amount of air pollutant emitted per gross energy output by the affected EGU or on allowable amounts of air pollutants emitted per energy input to the affected EGU . Reasons cited by the commenters for their opposition to requiring mandatory c ompliance with net energy output based emissions standards include: 1) a significant amount of the parasitic power demands at coal

- fired power plants is needed to operate the air pollution control equipment required to comply with air emissions standards; 2) there are monitoring difficulties in measuring net output , especially at facilities operating multiple EGUs; 3) parasitic loads vary on a individual EGU

-by

- EGU basis and, for a given EGU, on a duty cycle basis (e.g. as the load decreases on a typical EGU, the percent of parasitic power increases : 4) EGUs are not as thermally efficient at lower loads and consequently the amount of fuel that must be used increase s on an electrical output basis; 5 ) at facilities with affected EGUs and also at older, less ef

ficient EGUs which supply power to various auxiliaries throughout the plant, requiring the proposed net output

-based NSPS on the affected EGU could actually decrease overall plant efficiency; and 6 ) a net output approach will be problematic with emerging technologies such as IGCC and certain greenhouse reduction technologies such as carbon capture and sequestration (CCS). **Response:** The final rule allows, but does not require, the use of a net

- output based standard as an alternative to the gross

- output based standard. However, the use of a gross output

-based standard as it is presently defined could potentially drive the installation of electrically driven boiler feed pumps instead of steam driven boiler feed pumps. From an overall net efficiency basis, it is often more efficient to use steam driven boiler feed pumps, although a facility that uses electrically driven pumps would appear more efficient when using the present definition of gross output. Electrically driven boiler feed pumps could account for as m uch as 3% of the gross electric output of a coal

- fired EGU, substantially increasing the parasitic power requirements. Therefore, we are amending the definition of gross output for new facilities to be the gross output from the generator(s) minus any electric power requirements to drive the boiler feed pumps. Since boiler feeds pumps are specific to individual boilers, the monitoring issues mentioned by the commenters are no longer applicable. In addition, the majority of larger EGUs use steam driven boiler feed pumps and would not be impacted by the amendment. Furthermore, the primary parasitic power requirements for an IGCC facility that account for the primary differences between the net and gross efficiency with a PC boiler are the gas compressors (air s eparation unit main compressor, oxygen compressor, and nitrogen compressor). Correspondingly, the gross parasitic power requirements for an IGCC facility would also subtract out the electric power required to run these compressors. For facilities that coproduce chemicals, only a portion of the power would be subtracted from the gross output. **Comment:** Several commenters (4698, 4766, 4768, 5000) disagree with EPA’s proposal to calculate the net energy output for an EGU from the EGU’s gross energy output, assuming a 5% parasitic electric load loss factor. Actual parasitic load can vary across EGUs depending on site

- specific factors such as geographic location, EGU operating mode, and equipment selection. All of these factors affect a facility’s overall auxiliary power load and hence its net energy output. Therefore, a uniform 5% assumption is inappropriate . One commenter (4698) recommends that EPA solicit input from EGU architect and engineering companies to develop auxiliary load estimates for a range of EGU s izes and configurations. Another commenter (4768) states that a 10% parasitic electric load loss factor would be a more representative value. One commenter’s (5000) experience is that approximately 7 to 8% of a conventional coal fired station’s power is re quired to run auxiliary equipment. The commenter believes that this is a more representative value across the industry considering that units generally will be operating with SCR, FGD, and PM emissions controls, all of which require auxiliary power. Also, if a CCS is used in the future, the amount of auxiliary power will dramatically increase.Response to Comments on Proposed NSPS Amendments to Subparts D and Da

5 **Response:** According to the National Energy Technology Laboratory in the document “ Cost and Performance Baseline for Fossil Energy Plants ,” parasitic power requirements for pulverized coal

- fired boilers using supercritical steam conditions varies from 5.2% for high rank coals to 5.9% for low rank coals. These estimates are best an detailed designs and are the best estimates available to EPA. However, in recognition that parasitic power requirements can increase in terms of percentage of load at lower loads the final rule uses a 7.5% parasitic load assumption. **Comment:** One commenter (5210) states that output

-based standards are only truly effe ctive when determined by using output based data. The commenter requests that EPA not use input based data to set the NSPS standards and then simply convert those standards to output based numbers. Instead, the commenter recommends that EPA finalize output

-based standards, based on output data, for all pollutants, regardless of whether compliance is based on performance tests or continuous emissions monitoring systems (CEMS). **Response:** Output

-based emissions data was used to establish the amended emissions standards. 

## 2.1.4 **Standards for Reconstructed and Modified EGUs**  **Comment** : One commenter (5715 ) state s that EPA’s proposal to allow modified and reconstructed EGUs to meet less stringent NSPS emission limits than those required for new EGUs is not authorized by the CAA , and is therefore unlawful. The proposed NSPS for reconstructed and modified EGUs contradict Congressional intent that as existing sources are upgraded , they control their emissions to a rate reflecting best system of emission re duction for the industry. The commenter cites specific CAA sections and past court decisions to support this comment. **Response:** Standards under section 111 of the Clean Air Act must be achievable. See, National Lime Association v. EPA, 627 Fed. 2d 416 (D.C . Cir. 1980). Certain existing facility designs are not capable of operating combustion controls as effectively as newly designed facilities and, therefore, cannot achieve the same level of emissions reductions as newly designed facilities through the use of combustion controls. Further, even using the most efficient post combustion controls these facilities are not able to achieve the same NO X emissions rate as a newly designed facility. In determining what is achievable, EPA must consider costs and for mo dified facilities, the incremental cost effectiveness of adding a second scrubber to reduce SO2 emissions beyond what is achievable by currently installed technology is not cost effective. The new source PM standard is based on the use of a fabric filter. Existing facilities potentially don’t have adequate space available to cost effectively retrofit an existing ESP with a fabric filter. 

## 2.1.5 **Standards for Combined Heat and Power (CHP) Units Subject to NSPS Comment:**  One commenter (5074) states that the net output

-based standards in the NSPS should be modified in the final rule to account for both the thermal and e lectric generation from combined heat and power ( CHP ) and waste heat recovery systems subject to the NSPS . Absent this, the net output

-based standards fail to account for (and incentivize) the full efficiency gains associated with such systems. **Response:** Based upon comparison of the criteria pollutant emissions that would result from generating the thermal and electric output in separate facilities, EPA increased the thermal credit from 50% to 75% in 2006 ( 71 FR 9866 ). The definition is as follows: Gross output means the gross useful work performed by the steam generated and, for an IGCC electric utility steam generating unit, the work performed by the stationary combustion turbines. For a unit generating only electricity, the gross useful work performed is the gross electrical output from the unit's turbine/generator sets. For a cogeneration unit, the gross useful work performed is the gross electrical or mechanical output **plus 75 percent of**  **the useful thermal output measured relative to ISO conditions that is no t used to generate additional**  **electrical or mechanical output or to enhance the performance of the unit ( i.e.**  **, steam delivered to an industrial process).**  **Comment:** EPA requested comment on, “whether it is appropriate to recognize the environmental benefit o f electricity generated by CHP units by accounting for the benefit of on

- site generation , which avoids losses fromResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

6 the transmission and distribution of the electricity.” One commenter (5074) states that these avoided losses should be recognized because suc h savings are one of the key benefits of distributed generation. Several commenter s (4926 , 5074 ) state that that for CHP units subject to the NSPS, a 5% benefit for avoided transmission and distribution losses is too low. EPA should 

### adopt a higher multiplier that fully credits the transmission and distribution savings of CHP and therefore incentivizes such investments. **Response :**  EPA acknowledges that overall transmission and line losses are closer to 10%. However, the CHP facilities typically covered by subpart Da are large facilities with relatively large amounts of the generated electricity being transmitted to other end users, and the benefits are reduced. Therefore, the 5% credit is reasonable and adequately recognize s the environmental benefit of CHP compared to separate electric and thermal generation. 

## 2.1.6 **NSPS during Periods of EGU Startup, Shutdown, and Malfunction Comment:**  Comments were received in support of and in opposition to EPA ’ s proposal that NSPS emission limits app ly at all times, including start up, shut down and malfunction ( SSM) . C ommenter s (4698, 5210) support the proposal for a number of reasons. The c ommenter s state that startup and shutdown periods are normal phases of EGU operation and should not be held sep arate from other normal operating activities. Reasons stated by c ommenter s (4832, 4834 , 4839, 4841, 4984, 5077, 5470 ) opposing the proposal were varied. One commenter (4714) states that the DC Circuit Court decision regarding emission limits during SSM periods (Sierra Club vs. EPA, DC Circuit Court, 2008) was specifically regarding NESHAP rules and not NSPS rules. EPA has not provided any reasoned explanation or justification for why it is applying the same approach for new, modified, and reconstructed sources in the proposed NSPS rule revisions. Furthermore, EPA has not appropriately evaluated applying the same emission limits for normal operations and for SSM periods. Another commenter (4836) state s that coal

- fired EGUs co

- fire other fuels (typically natural gas or oil) during certain operating modes , such as startup, shutdown, and flame stabilization operations. The proposed NSPS do not address the potential emissions from these co

- fired fuels, which will have different emissions profiles from the times the EGU burns coal only. One commenter (4834) state s that instead of emission limits , work practices should be proposed for the NSPS to control emissions during SSM periods. Another commenter (4839) state s that provisions for SSM periods should follow precedent in the Industrial Boiler MACT Rule. Many of the commenters opposing the proposal state that work practices should be used to control emissions from EGUs during startup and shutdown. For malfunctions, a source should have to address the malfunction as soon as safely practicable. One commenter (17975) states that s ince maintenance activities are generally carried out for EGU boilers after they have been turned off , the distinction between “maintenance” and “startup/shutdown” is meaningless

. **Response:** The NO X and SO 2 CEMS data used to establish the standards include all periods of operation and it is therefore not necessary to attempt to separate the data and establish separate numerical standards during normal operation and periods of startup and shutdown. However, since we did not have CEMS data for PM emissions, we are establishing work practice standards for control of PM emissions during periods of startup and shutdown. 

## 2.1.7 **F acility** 
**- Wide Emissions**  **Averaging Comment:**  One commenter (4839) stated that f acility

- wide emissions averaging should be allowed as a compliance alternative in certain circumstanc es. EPA should reconsider and support including facility

-wide averaging in emission limitations for existing sources subject to the NSPS as an additional compliance alternative. By including this type of flexibility mechanism, EPA will ensure that facilities will retain some degree of flexibility when complying with the rule requirements. Similarly, varying operational modes or combination of systems (e.g., wet/dry scrubber, ESP or fabric filter) could be employed to provide the greatest potential for economically reducing emissions to meet compliance requirements. EPA’s averaging formula should be constructed so that the average emissions by a group of EGUs subject to the NSPS will be no more than what is permitted on an aggregated individual basis. From a practical standpoint, the ability to monitor units with shared stacks may present technical difficulti es to the point where separate monitoring is simply not feasible. **Response:** While the suggested approach would provide additional flexibility without an increase in emissions to the atmosphere, the present applicability of the NSPS is on a boiler by boiler basis and no change to that approachResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

7 was proposed. Facility

-wide averaging would require a notice and comment rulemaking to at a minimum clearly identify the affected facility, how the averaging would be done , and how modifications and reconstructions would be determined. 

## 2.1.8 Interrelationship of NSPS with other EPA Rulemakin **gs Affecting EGUs 2.1.8.1 Source Category Impact Analysis**  **Comment** : One commenter (4760) states that EPA needs to analyze the combined impacts of all regulatory proposals to the electric industry. Decisions by U.S. electric utilities to add needed electricity generating capacity are being impacted by the breadth and compl exity of the numerous rules

-- including the NSPS amendments that EPA is implementing to regulate EGU. **Response:** The amendments to the NSPS would have a negligible incremental impact on the cost of new coal

fired generation. Annual costs, compared to the existing NSPS requirements, will increase less than 0.3%. In addition, the various regulatory actions impacting air emissions from EGUs require similar controls such that the actual impacts of the NSPS amendments would be even less. **Comment** : One commenter (4 832) states that EPA proposing substantive changes to 40 CFR 60 subpart Da is outside the scope of the proposed NESHAP rulemaking and the changes have not been properly analyzed or justified. Specifically, EPA is proposing to demonstrate compliance with certain HAP emissions limits under the NESHAP by proxy methods that refer back to SO 2 or PM limits established in 40 CFR 60 subpart Da. **Response:** While the proposed SO 2 and PM NSPS amendments are not expected to have any benefits or costs due to the similar benefits and costs in the new source EGU NESHAP requirements, they would be cost effectively achievable in the absence of the NESHAP. Docket entry EPA

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- 0002 includes detailed incremental cost effectiveness calculations for each pollutant and EPA has concluded the amended standards are justified in the absence of the NESHAP. If cost and benefits of the proposed amendments were included, it would double count the impacts of the rules. 

### 2.1.8.2 Delay of NSPS Rulemaking until NESHAP Affecting EGU **s is Finalized Comment**  : One commenter (4839) states that the substantial technical comments submitted for the EGU NESHAP warrants a delay of the proposed NSPS to allow EPA sufficient time to consider the more comprehensive affect these revised rules will have on the utility sector. In addition, there are some commonalities in the controls needed to comply with the requirements of the two rules. Syncing the two rules such that they apply to the same set of new sources will allow owners/operators of those sources to better plan for compliance. Finally, since EPA is not under any judicial timeline to promulgate the proposed NSPS, the commenter recommends a delay to account for the considerable time EPA will need to revise the EGU NESHAP and respond to any potential judicial challenges. **Response:** While the EGU NSPS amendments and NESHAP were included in the same package and are related in the types of required controls, they are independent rulemakings that both serve the purpose of reducing emissions of pollutants. EPA has sufficiently replied to comments submitted on both proposals. 

### 2.1.8 **.3 Proposal of EGU NSPS Amendments**  **with EGU NESHAP Comment**  : Several commenters (4839, 5087) state that the inclusion of a proposed NSPS rule within the extensive and comprehens ive proposed EGU NESHAP is inappropriate and circumvents the appropriate comment period that should be afforded each rule individually. The release of NSPS and EGU NESHAP in the same proposal notice with one 60

- day comment period suggests that EPA is rushing its regulatory agenda and short

circuiting the regulatory process. Since EPA is not under a court ordered deadline to develop NSPS amendments, each of these rulemakings should have been proposed separately with their own comment period. **Response:** The proposed 60 day comment period was extended an additional 30 days to provide sufficient time for the public to review and comment on both proposals.Response to Comments on Proposed NSPS Amendments to Subparts D and Da

8 

## 2.2 **Rule Applicability 2.2**  **.1 Regulation of IGCC**  **facili ties under 40 CFR 60 s**  **ubpart KKKK Comment**  : EPA requested comment on whether or not an IGCC EGU that co

-produces hydrocarbons or hydrogen should be subject to the combustion turbine NSPS under 40 CFR 60 subpart KKKK instead of the EGU NSPS under 40 CFR 60 subpart Da

. Several commenters (4836, 5715) state that an IG CC EGU that coproduces hydrocarbons or hydrogen should be subject to subpart Da. One commenter (4836 ) state s that IGCC EGUs are designed and structured differently than natural gas

- fired combined cycle EGUs. For the sake of clarity and regulatory certainty, there should not be a mechanism that would require a particular EGU to switch back and forth between different NSPS standards , even if an IGCC is capable of using natural gas as a fuel. Such units that may co -produce hydrocarbons or hydro gen still convert coal or oil into electricity , and apportioning the parasitic load would be difficult. The commenter requests that EPA provide a heat input

-based alternative based on the raw feed stock to the gasifier for these units instead of struggling to make them demonstrate compliance with an output

-based standard. Another commenter ( 5715 ) states that not applying subpart Da to certain IGCC EGUs that co -produce hydrocarbons or hydrogen is not logical. All IGCC facilities that sell more than one third their potential electric output capacity and more than 25 megawatts of electricity ( MWe ) to the grid are and should be classified as an EGU subject to 40 CFR 60 subpart Da whether the EGU produce s other useful byproducts or not , consistent with the applic ability of EGUs to 40 CFR 60 subpart Da that are classified as combined heat and power units. **Response:** The IGCC facilities that meet the existing applicability criteria will continue to be regulated under subpart Da. EPA concluded that a gross output base d standard, including the revised definition of gross output, is appropriate and can be relatively easily measured for all affected facilities, including IGCC facilities. A heat input based standard would require an IGCC facility owner/operator to measure the coal input to the gasification system and assume all of the energy is input to the stationary combustion turbine and heat recovery steam generator, and calculate a site specific f

- factor along with a stack flow meter and CO 2 CEMS or a fuel flow meter. EPA has concluded that the additional complexity associated with such an approach would not yield improved result compared to an output

-based standard. 

## 2.2.2 **Exempt ion of**  **EGUs Using “Innovative Technologies” Comment**  : One commenter ( 5715 ) state s that EPA i s not authorized under the CAA to allow the proposed exemption of certain EGUs using “innovative technologies” f rom complying with the NSPS emissions standards. The CAA only allows EPA to grant a compliance time extension for such affected EGUs on a case

-b y - case basis th at meet certain conditions specified in the statu t e. Several commenters (4839, 4893, 4984) support the proposed exemption. One commenter (4839) requests that to avoid precluding the development of new technologies, EPA should consider a broader applicability of the exemption to include all DOE

- funded commercial

- scale technology demonstration projects. **Response** : As explained in the preamble, the compliance time extensions under section 111(j) of the Act are not adequate for owners/operators of affected facilities subject to this subpart to secure the funding necessary for construction of certain capital intensive projects. As such, the development of promising technologies that offer potential reductions in criteria, hazardous, and GHG emission s could be restricted. The permits will be granted on a case -by

- case basis and depend on the anticipated emissions performance of the specific technology. To preclude development of emerging technologies that offer potential for future emissions reduction s, the commercial demonstration permit exemption will be maintained as proposed for pressurized fluidized beds and multi

-pollutant control technologies. Neither of these technologies is generally applicable to existing facilities, and overly stringent standards could impede their future development and make financing projects cost prohibitive. The majority of existing facilities already have some form of emissions control technology. Installing a multi

-pollutant control technology is not necessary and pressurized fluidized beds are sufficiently different from traditional designs that retrofits are unlikely. However, advanced combustion controls are applicable to existingResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

9 facilities and the exemption is not necessary to further the development of the technolo gy. That exemption is not included in the final amendments. DOE

- funded technology demonstration projects are typically installed at existing EGUs and would not trigger applicability with the NSPS requirements. Therefore, the exemption would not be applicable. If in the future DOE were to request EPA evaluate the exemption for DOE

- funded technology demonstrations it could be considered in a future rulemaking. 

## 2.2.3 **Applicability to Permitted EGUs for**  **which C onstruction**  **Has Not C ommenced**  **Comment:** One commenter ( 4830 ) state s that EPA must appropriately accommodate permitted facilities for which construction will not have commenced prior to the date of the NSPS regulation. Several electric utility entities have recently obtained air permits authorizing the construction of new units . However , they were not in a position to commence construction on these new units prior to the date that EPA intends to apply the proposed NSPS to facilities that have not commenced construction ( May 4, 2011 ) . As a result, the se units will be regulated as new sources under this proposed rule. This situation creates significant inequities for the projects that are permitted but have not commenced construction prior to the proposed NSPS, and ultimately, this proposal may prevent the projects from being implemented, depending on the NSPS adopted in the final rule. **Response :**  Section 111(a) of the CAA defines a new source as one for which construction or modification commences after the publication of proposed regulation applicable to the source. In this case, the relevant date is May 4, 2011 and any source which commences construction or modification after that date is a new source for purposes of the final regulations. EPA has long defined “commenced” in this context to mean “that an owner or operator has undertaken a continuous program of construction or modification or that an owner or operator has entered into a contractual obligation to undertake and complete, within a reasonable time, a continuous program of construction or modi fication.” 40 CFR 60.2. Merely obtaining an air permit authorizing construction does not meet this requirement. Furthermore, EPA disagrees that the NSPS amendments will prevent projects from going forward since, on average, the standards have minimal impac t on the capital cost of a new EGU, cost less than $10/kW (less than a 1% increase) , and are achievable for a range of technologies and coal types. Therefore, we have concluded that the amended standards would not require significant redesign of already permitted facilities or impact the decision on the type of boiler or fuel selection. 

## 2.3 Particulate Matter (PM) **Em issions**  **Standards 2.3.1 Selection of**  **BSER for PM Emissions**  **Comment:** Several commenters (4765, 4836 , 5089, 5715 ) state that the proposed NSPS for PM emissions does not reflect the application of BSER systems of emissions reduction. Commenters differ as to which PM emissions control technologies should be used as BSER for establishing the NSPS emission limits. One c ommenter states that EPA’s proposal to require new facilities to meet the same limits already achieved by many existing sources is contrary to the clear requirements of the statute and Congressional purpose to require new sources to apply the best demonstrated systems of pollution control. Instead, EPA sets PM standards that are “achievable” by all new sources (and even many existing sources) rather than standards that are “achievable” through the application of the best adequately demonstrated system of emissions control, as the CAA requires. One commenter (4765) states that the CAA § 111(a)(1) does not allow EPA to base an NSPS on a BSER that is a combination of technologies and EPA has not attempted to do so in the past. **Response:** The amended PM standard i s a filterable only standard and the BSER would therefore only include a fabric filter

. The BSER can take into account multiple factors including, but not limited to, choice of generation technology, fuel selection, and multiple emission control technologi es. Nothing in the CAA limits BSER to a single emissions control technology. 

## 2.3.2 **Regulation of Combined PM Emissions**  **Comment** : Many c omments were received in support of and in opposition to the proposal to establish a new combined PM emissions limit for EGUs that is determined by adding the measured c ondensable PM plus theResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

10 measured filterable PM. C ommenter s ’ (4698, 4710, 5715, 5210) reasons for supporting the proposal include 1) some s tate permitting agencies already regulate condensable PM for steam generating ; and 2) methods now exist to both measure and control condensable PM. One commenter (4714) notes that the State of Texas has regulated condensable PM through permitting for more than three decades. Commenters ( 4712, 4766, 4836, 4989, 5075, 5077, 50 89, 5208 ) oppose the proposal for a number of reasons. C

### hanging the existing NSPS for PM from a filterable PM standard to a combined PM standard by basing the proposed emissions limit on the performance of the top 20% best performing units is unlawful and arbitrary. EPA cannot establish a combined PM emissions limit because the Agency failed to follow the CAA statutory requirements for establishing a standard by not identif ying the condensable PM component, how to control condensable PM, or what BSER is for reducing condensable PM emissions. Also, BSER for filterable and condensable PM components are separate. 

### There is no basis for establishing an emissions limit at the emission rate expected by the best performing 20% of the industry, when EPA has not provi ded any guidance on how the rest of the industry might seek to comply. Commenters also state that the proposed compliance procedures for the combined PM standard are unworkable because EPA Test Method 202 is inadequate to measure the condensable PM component. **Response:** EPA Test Method 202 was promulgated in December 2010. The revised test method is as precise and accurate in measuring condensable PM as Method 5 or 17 are at measuring filterable PM. We have provided responses in the NESHAP response to comments concerning the reliability of Method 202. As such, we have concluded that it would be possible to establish and determine compliance with a combined PM standard (Method 5 plus Method 202). Based on comments received and on further consideration since the proposal, h owever, EPA has concluded it is appropriate to amend only the filterable PM standard at this time. In a future rulemaking, we will specifically request comment on : i) the appropriate monitoring procedures, ii) whether separate standards for condensable PM and filterable PM have any benefit over a combined PM standard, and ; iii ) the appropriate numerical standards in each case. In addition, while EPA collected over 200 source tests for condensable PM from the Utility Boiler ICR, these tests represent only a single test for each facility. Therefore, subpart Da is amended to require Method 202 testing and reporting of those emissions each time a Method 5 or 17 performance test is performed. This approach minimizes the burden to the regulated community, while at the same time collecting sufficient data for evaluation. If appropriate, EPA will include condensable PM in the PM standard in a future rulemaking that accounts for annual variability. The incremental cost of Method 202 over Method 5 or 17 is less than $7 00 (10% of PM testing cost). The proposed NESHAP ICR assumed condensable PM testing for all facilities subject to the NESHAP. The amended NSPS ICR accounts for the subset that will be required to test under the NSPS. While EPA plans on evaluating separate filterable and condensable PM standards, we support the present approach that several recent permits have taken in establishing a combined PM standard that includes both filterable and condensable PM. Controls required by an NSPS help in achieving and protecting the NAAQS

. In the context of a PM standard , the relevant NAAQS is for PM 10 and PM 2.5 . For this source category, a combined PM measurement represents mostly PM 2.5 since the filterable controls remove the larger sized PM. The primary distinction between filterable and condensable PM is based on temperature , not the form of the PM in the ambient air. The NSPS establishes standards that can be met through the use of the best controls for managing the ambient air pollutant. We chose to is sue a filterable only standard, rather than a combine d PM standard, in part because of the inability to quantify particle size in a wet stack environment and recognition that many new EGU will employ wet scrubbers

. Further, while the technology that best c ontrols filterable PM may be different from that which best controls condensable PM, the available data does not establish a distinct line that differentiates filterable PM and condensable PM This is demonstrated by the fact that the Part III EGU NESHAP ICR data, indicates that some units with lower combined PM emissions had relatively low filterable PM emissions with somewhat higher condensable PM emissions, while other units had a more balanced control of filterable and condensable PM. In the proposal, we identified dry sorbent injection (DSI) to neutralize SO 3 to sulfate prior to removal by a mist eliminator or particulate control and a wet ESP as control technologies for condensable PM. However, there are several additional measures that control condensable PM. These include, but are not limited to, (1) the selection of catalysts which minimize the formation of SO 3 from SO 2 , (2) minimizing the temperature at which the particulateResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

11 matter control device operates, (3) minimizing the ammonia slip when SCR or SNCR is used, and (4) a more efficient mist eliminator. In addition, the sulfuric acid mist portion of condensable PM emissions is strongly dependent on the sulfur content of the incoming coal. All of these factors need to be taken into consideration in establishing a meaningful national standard. At this time we do not have sufficient knowledge to determine the combination of control technologies which will achieve the best level of control of both filterable PM and condensable PM and, thus, cannot establish a technical basis for an appropriate national combined PM emissions standard. The additional condensable PM test data will allow us to evaluate the capabilities of a combination of techniques to reduce PM emissions. One potential outcome would b e a PM standard that is based on the sulfur content of the coal, similar to the format for the SO 2 emissions standard. Since we did not propose that approach, we plan on doing a future notice/comment rule that specifically requests comment on the best approach for achieving the best level of control of both filterable and condensable PM. Even though we are not establishing a PM standard that includes condensable PM, emissions of condensable PM by facilities subject to the amended requirements in subpart Da would not be uncontrolled. All new facilities in this source category would be subject to PSD and be required to account for condensable PM in performing the required analysis under that program . In addition, condensable PM emissions are generally lower f or facilities with lower filterable PM emissions and high SO 2 control rates and since the amended NSPS will require greater control of the emission of these pollutants, there should be some reduction in condensable PM. PM controls are more efficient at capturing filterable PM at lower temperatures and a greater proportion of the condensable PM will be solid and thus captured by the PM control device . The SO 2 relationship results from the increased liquid to gas contact capturing more of the condensable PM. 

## 2.3.3 Regulation of PM **2.5** 

## Emissions **Comment** : One commenter (4841) states that a separate filterable PM 2.5 should not be established due to both measurement issues with respect to wet stacks and also because control technologies installed for combined PM, N O X , and HCl/S O 2 will result in reductions of both direct PM 2.5 and PM 2.5 precursors. **Response:** T he final rule amendments do not include a standard for PM 2.5 . 

## 2.3.4 Selection of **PM Emissions Limit Value**  Comment: Several commenters (4714, 4765, 4836, 5075) state that the proposed PM emissions limit is not achievable on a nationwide basis, and as a result the final rule needs to be revised upwards to reflect the actual levels of performance achievable. Several commenters (4673, 4836) state that the proposed PM emissions limit is so stringent that it would effectively preclude construction of new coal

- fired EGUs. Several commenters (4712, 4989) state that the methodology EPA used to select the proposed PM emissions limit value does not sufficiently address variability in EGU fuel use, equipment design, and operation. One commenter (4713) state s that PM emission limits for new source EGUs should be the same in the NSPS and NESHAP. One commenter (5210) examined the emissions limits in 27 permits and permit applic ations for proposed coal

- fired EGUs and conclude s that a c ombined PM standard of 0.030 lb/MMBtu best reflects BSER for new EGUs. Moreover, of the 27 permit and permit application limits reviewed, 14 listed both a filterable PM limit and a c ombined PM limit. The commenter also requests that EPA either adopt the most stringent feasible filterable PM standard for modified EGUs or finalize a c ombined PM standard that reflects a BSER requiring additional controls for condensable PM for these unit s . **Response:** For the reasons explained previously , EPA is issuing a final standard for filterable PM only and that standard is appropriate for a national requirement as it represents BSER for both new and modified facilities and takes variability into acc ount. The amended standard is technology and fuel neutral and multiple PC and FB EGUs burning various coal types are presently operating below the amended standard. Finally, the amended standard is consistent with the NESHAP and the 0.090 lb/MWh PM standard accommodates IGCC facilities in multiple operating modes. **Comment** : One commenter (5279) states that the proposed PM emissions limit should be revised to address the use of duct burners at IGCC facilities when fired using syngas and using natural gas. The commenter states thatResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

12 higher PM emission limits than the proposed limit are required when operating under either of these two scenarios. **Response:** The PM standard is based on the permit conditions for an IGCC and accounts for both operating conditions. 

## 2. **3.5 PM Control Cost Analysis Comment**  : Many commenter s ( 4635, 4656, 4765, 4766, 4686, 4830, 4836, 5075, 5089, 5240 ) state that EPA failed to independently calculate the control costs for implementing the proposed PM emissions limit as required by the CAA § 111(a)(1). It specifies that EPA 

### “tak[e] into account the cost of achieving such reduction and any non - air quality

health and environmental impact and energy requirements...” when establishing NSPS. Instead, EPA 

### has unlawfully relied on the PM emission s reductions that it anticipates to occur through implementation of the proposed NESHAP for EGUs. EPA 

### concludes that the proposed NSPS PM emissions limit 

### will not result any costs or benefits attributable to implementing the NSPS. **Response:** Docket item EPA

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. 

## 2.3.6 PM Standards Exemptions **2.3.6 .1**  **Opacity Standard Exemption for**  **EGUs Using PM CEMS**  **Comment** : Several commenters (4673, 4766, 4836 ) state that EPA should e xempt EGUs subject to 40 CFR 60 subpart D and using PM CEMS from the opacity s tandard requirements

. F or affected EGUs that monitor PM emissions directly with a method EPA has determined a s “sufficiently accurate,” the surrogate opacity standard is no longer necessary to assure comp liance with the applicable PM emissions limit. EPA should finalize the exemption proposed in 2008 for any EGU subject to 40 CFR 60 subpart D that demonstrates continuous compliance with the applicable PM emissions limit on a 24

-hour (not 3

-hour) average basis. **Response:** We agree with the commenters that using PM CEMS provides not only a continuous check on the ability of the PM control device to minimize filterable PM emissions but also a direct, continuous measure of compliance with the filterable PM emissions standard. The rule allows source owners or operators who choose to use PM CEMS with a three hour averaging time demonstrating continuous compliance with the filterable PM emissions limit to drop the requirement for COMS for purposes of the NSPS

. Should source owners or operators want a different averaging time, they can petition the Administrator in accordance with the requirements in 40 CFR 60.42(c). Furthermore, the EGU NESHAP includes an existing source filterable PM standard of 0.030 lb/MMBtu as an alternate to measuring total metals. Therefore, the vast majority of subpart D facilities will be install ing controls that would allow them to control PM emissions to such an extent that the opacity standard would no longer be applicable. 

### 2.3.6.2 **Opacity Standard Exemption for**  **EGUs Complying with a**  **Combined PM Standard**  **Comment** : One commenter ( 4836 ) supports EPA’s proposed opac ity s tandard exemption for affected EGUs complying with a combined PM emissions limit. **Response:** The final rule amendments do not include a combined PM emissions limit (see Section 2.3.3) and, therefore, the proposed exemption is no long er relevant

. 

### 2.3.6.3 **PM and Opacity Standard**  **Exemptions for Natura** **l Gas Fired EGUs Comment**  : Several commenters (4836, 4841, 17711, 17852 ) support EPA’s proposed opac ity s tandard exemption for natural gas fired EGUs. However, one commenter (4836) does not understand why EPA proposes to limit the Subpart D exemption to those facilities subject to a federally enforceable permit limiting fuel use. No such condition is attached to the proposed Subpart Da exemption. The commenter also does not understand why EPA has not proposed to exempt Subpart Da facilities that combust only natural gas from the filterable PM standards. Those facilities also will have negligible filterable emissions. As long as the facility is actually c ombusting onlyResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

13 natural gas, it should be exempt from filterable PM and opacity standards regardless of a pre

- existing permit restriction. One commenter (17852) also states that the option to integrate combustion turbines and/or fuel cells with steam generating units is another good way to reduce emissions. The commenter also states that if an owner chooses to integrate and connect a fuel cell or combustion turbine to a steam boiler to use waste heat to improve efficiency, they should be able to elect to consider them an integrated unit for compli ance purposes. **Response:** The “federally enforceable permit” requirement has been removed from subpart D. The second part of the comment is unclear since the proposed language in paragraphs § 60.42Da(a)(4), (e), and (g) exempt natural gas - fired EGUs from the PM standard. **Comment** : One commenter ( 5749 ) state s that EPA should clarify the circumstances under which 40 CFR 60 subpart Da may apply to gaseous fuel firing, where such gaseous fuel is not a fossil fuel (for example, where a non fossil gaseous fuel is c ombusted in combination and/or alternately with a fossil fuel). To the extent that Subpart Da would apply under any such circumstance, EPA should extend the Subpart Da exemption from PM and opacity limits for natural gas units to also apply to gaseous fuel fired units , such as those firing landfill gas. The commenter believes that landfill gas and other non fossil gaseous fuels have similar emission profiles to natural gas, and should be encouraged as viable alternatives to fossil fuels, including natural gas. **Response:** A facility that only burns non fossil gaseous fuels would not be subject to subpart Da. Subpart Da only appli es to owners/operators of facilities capable of combusting more than 250 MMBtu/h of fossil fuel and supplying more than one

-third of its potential electric output capacity and more than 25 MW net

- electrical output to any utility power distribution system for sale

. Owners/operators of that meet the fossil input requirements and co - fire non fossil fuels would be subject to subpart Da. We have concluded it is not appropriate to provide an outright exemption for all co - fired gaseous fuels since they can potentially contain contaminants that result in PM emissions and opacity. However, the amount of sulfur in a gaseous fuel is a general indic ation of the amount of impurities. Therefore, gaseous and liquid fuels with potential SO 2 emissions rates of less than 0.060 lb/MMBtu are included in the PM exemption, but not the opacity exemption. Other gaseous fuels do not necessarily burn as completely as natural gas. Subpart Da already includes reduced opacity monitoring for owners/operators burning gaseous fuels other than natural gas. 

### 2.3.6.4 **PM and Opacity Standards Exemption for Low** 
**- Sulfur Fuel**  **Fired EGUs Comment**  : One commenter ( 4836 ) support s EPA’s proposal to exempt EGUs that combust only gaseous or liquid fossil fuel with potential SO 2 emission rates of 0.060 lb/MMBtu or less from the otherwise applicable filterable PM standard , provided the EGU does not use post

- combustion SO 2 or NO X controls . One commenter does not support this option for other forms of oil, especially for No. 4 oi l and other grades. Another commenter (4698) opposes the exemption because opacity emissions from EGU firing such fuels is not generally due to fuel ash and impurities but rather is more a function of incomplete fuel combustion. **Response:** EPA agrees that opacity and filterable PM emissions from low sulfur oil

- fired boilers are a result of incomplete combustion and do not result from fuel ash or impurities. However, EPA believes that 20% opacity would rarely occur at facilities burning these fuels. Therefore , subparts D, Da, and Db are amended to include a provision providing state permitting authorities the flexibility to approve site

- specific monitoring requirements for distillate oil containing less than 500 ppm sulfur, while still maintaining the opacity standard itself. This flexibility will be especially beneficial to owners/operators who only burn distillate oil as a backup fuel. The state would then have the flexibility to either require the procedure set forth in the rule or the owner/operator could monitor carbon monoxide emissions as an alternative. 

## 2.4 **Sulfur Dioxide (SO 2**  

## ) Emissions Standards **2.4.1 Selection of BSER**  **for SO 2**  

## Emissions **Comment** : Many commenters ( 4712 , 4715, 4765, 4836 , 5715, 4989 ) state that EPA failed to state the BSER that the Agency selected as the basis for establishing the proposed SO 2 emissions standards. One commenter ( 5715 ) state s that the proposed SO 2 emissions rates are not the result of an analysis of the application or performance of BSER systems of SO 2 emiss ion reduction

– instead they are based on the SO 2 emissions rates that are alreadyResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

14 being achieved by existing EGUs. EPA’s BSER determination analysis was not based on the application of new and innovative multi

-pollutant control options nor the application of systems of emissions reductions that allow control of greenhouse gas emissions (which EPA is regulating under a separate rulemaking) along with control of SO 2 . **Response:** The BSER for SO 2 is the same as in the 2006 final amendments, low sulfur coal and a spray dryer or high sulfur coal and a wet scrubber. In this remand, the achievable standards were reevaluated, but no new technology developments have taken place so the BSER technologies were not changed. The facilities used to establish the numerical standard used low sulfur coal and a spray dryer, and the facilities used to establish the percent reduction requirement burned high sulfur coal and used a wet scrubber. EPA has concluded it is not appropriate to base the amended SO 2 standard on potential GH G requirements that have not been proposed. 

## 2.4.2 Selection of SO **2** 

## Emissions Limit Value **Comment** : Many commenters (4715, 4765, 4768, 4836, 5715, 4989, 5075, 5077) state that the proposed NSPS SO 2 emissions limit does not reflect the application of BSER systems of emissions reduction, and the methodology EPA used to select the proposed SO 2 emissions limit value does not sufficiently address variability in EGU fuel use, equipment design, and operation. One commenter (4836) included an analysis of the data set used by the Agency in evaluating the achievability of the proposed SO 2 emissions limit using BSER

. Based on this analysis, commenters state that an appropriate SO 2 emissions limit is 1.25 lb/MWh for new units with an optional reduction limit of 96%. In contrast, another commenter (4715) states that EPA did not set the NSPS SO 2 emissions limit based on the best demonstrated unit in its data set . Nearly all of EPA’s sample units (12 of 15 units) could meet the proposed NSPS of a 97% reduction in SO 2 , and a third of the units (5 of 15 units) could meet a 98% reduction. Furthermore, all of the units in the data set that tested in the 97% reduction range, excepting one, tested in the upper limits of the 97% range. This fact indicates that a 98% reduction limit is achievable. EPA should incentivize the most efficient use of control technologies to achieve the maximum amount of SO 2 reduction. The reduction limit of SO 2 should be set at 98% for this NSPS. One commenter (5210) examined emissions limits of six existing coal units (at Intermountain Power, Colstrip, and Navajo) and the emissions limits in 29 permits and permit applications. Based on those data, the commenter recommends setting a SO 2 standard of at least 0.7 lb/MWh to reflect BSER for all EGUs. **Res ponse:**  Both fluidized beds and pulverized coal EGUs have demonstrated that a 97% reduction in potential SO 2 emissions is achievable. While short term data indicates that greater than 97% reduction may be achievable, it has not been demonstrated to be achievable on long term basis. Furthermore, a 97% reduction in potential emissions has only been demonstrated to be achievable for coals with nominal uncontrolled SO 2 emissions of greater than approximately 3.5 lb/MMBtu. Assuming a gross efficiency of 36%, this correlates to a numerical emissions rate of 1.0 lb/MWh. Setting a numerical standard below 1.0 lb/MWh could limit the ability to use medium sulfur coals in new EGUs and drive the market toward subbituminous and low

- sulfur bituminous coals. While subbituminous coal and low

- sulfur bituminous coal have inherently low sulfur content and thus low SO 2 emission rates, neither is a viable option for establishing a national standard as the use of these ranks of coal is not practicable for some units due to transportation constraints, costs, and supply limitations. The transportation logistics and costs render the use of subbituminous coal by all new coal

- fired generation unfeasible

. Subbituminous coal is mined in the western states and requires long distance transportation , resulting in increased emissions from locomotives, increased energy consumption, and potential additional rail line construction due to existing rail system limitations. The use of lower sulfur eastern bituminous coal is also problematic as it is in high demand across the eastern United States and abroad. The increased demand does not just come from the electric generation sector , the coal is also in demand for use as a raw material in manufacturing. In addition, available veins of low

- sulfur eastern bituminous coals are being exhausted

. A s a result, in recent years electric utilities have begun to bu

rn eastern bituminous coals with increasingly higher sulfur content levels. In addition, adding a subbituminous

- fired boiler at an existing site designed to burn bituminous coal would require significant design changes to the coal material handling and other existing ancillary equipment. **Comment** : One commenter ( 17622 ) states that Table 17

- SO 2 Emissions Performance Data in the proposal notice ( 76 FR 25065) used by EPA to select the SO 2 performance level for EGUs lists the best performing units in termsResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

15 of percentage SO 2 control and the subsequent commentary incorrectly indicates that with the exception of the HL Spurlock Units 3 and 4, all utilize wet limestone scrubbing technology. The three units at the Harrison Station utilize wet magnesium on demand lime scrubbing technology, not wet limestone technology. **Response:** The Harrison technology description has been corrected. 

## 2.3.3 SO **2** 

## Control **Cost An alysis**  **Comment** : Many commenter s ( 4635, 4656, 4765, 4766, 4686, 4830, 4836, 4989, 5075, 5240 ) state that EPA failed to independently calculate the control costs for implementing the proposed SO 2 emissions limit as required by CAA §111(a)(1). Itspecifies that EPA, 

### “tak[e] into account the cost of achieving such reduction and any non - air quality

health and environmental impact and energy requirements...” when establishing NSPS. Instead, EPA 

### has unlawfully relied on the SO 2 

### emissions reductions that the Agency anticipates from implementation of the proposed NESHAP for EGUs. EPA 

### concludes that the proposed NSPS SO 2 emissions limit 

### will not result any costs or benefits attributable to implementing the NSPS. **Response:** In proposal docket item EPA

- HQ

- OAR

- 2011

- 0044

- 0 002 an incremental cost analysis and a secondary environmental impacts analysis include control costs for implementing the proposed SO 2 emissions limit. On the basis of that information, EPA concludes the SO 2 limits are achievable and cost effective even in the absence of the NESHAP. 

## 2.4 **.4 Coal Refuse** 
**- Fired EGU**  **Exemption from SO 2**  

## Standards **Comment** : One co mmenter (5715) states that EPA’s proposal to exempt EGUs bur ning more than 75% coal

refuse on an annual basis from the proposed NSPS for SO 2 emissions and instead allow such units to meet the existing NSPS for SO 2 emissions is unlawful. The commenter states that in proposing to establish such an exemption, EPA failed to distinguish these EGUs as a subcategory warranting separate emissions standards in accordance with the proper statutory requirements as provided by 42 U.S.C. §7411(b)(2) (“the Administrator may distinguish among classes, types and sizes within categories of new sources for the purpose of [setting NSPS]. One co mmenter (5210) states that new coal refuse

- fired EGUs can meet the same standard that EPA is proposing to maintain the existing SO 2 emissions standard of 1.4 lb/MWh for owners/operators of affected facilities combusting 75 % or more coal refuse on an annual basis. The comment er recommends that EPA adopt a SO 2 standard of 0.07 lb/MWh output for units burning 75 % or more coal refuse. **Response:** Coal refuse

- fired facilities are subcategorized for the secondary environmental reasons stated in the proposal. The amended standards are based on the best performing coal refused

- fired EGUs. The Seward 1 and 2 coal refuse

- fired EGUs are the best performing facilities in terms of percent SO 2 control. Both have demonstrated that 94% reduction is achievable, but no coal

-refuse

- fired EGU has demonstrated greater than 94% reduction. Therefore, the percent existing percent reduction standard of 94% is BSER and unchanged. While we have no data that any existing coal refuse

- fired EGU is presently meeting the existing numerical SO 2 standard, we are maintain that standard to avoid backsliding of the NSPS. Similarly, the Northeastern 31 EGU is the best performing coal

-refuse

- fired EGU in terms of NO X . The facility has demonstrated a NO X emissions rate of 0.85 lb/MWh and we are therefore amending the standard accordingly. Furthermore, the previous 8 PM performance tests at the Northampton NGC01 coal refuse

- fired EGU have been under the amended PM standard of 0.090 lb/MWh. 

## 2.5 Nitrogen Oxides (NO **X**

## ) Emissions Standards **2.5.1 Selection of BSER**  **for N O**  **X** 

## Em**issions Comment**  : One commenter (5715) states that the proposed NSPS to control NO X emissions (a combined NO X/CO standards and an alternative NO X standard) does not reflect the application of BSER systems of emissions reduction. EPA’s selection of selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR) with advance d combustion controls does not represent BSER systems for control of NO X emissions. Furthermore, EPA failed to state the BSER that the Agency selected for controlling CO emissions. TheResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

16 commenter states that EPA’s BSER analysis did not evaluate the NO X and CO emissions reductions achievable by all available NO X and multipollutant control technologies. **Response:** Since SCR has not been widely applied to fluidized bed boilers, SNCR in combination with good combustion controls achieve the lowest NO X emissions rate, and are , therefore, considered BSER . Regenerative SCR is a relatively new technology and emissions rates are not yet available. For pulverized coal boilers, BSER was determined to be the use of advanced combustion controls and SCR. The only currently viable CO controls on EGUs are combustion controls. 

## 2.5.2 **Combined NO X**  

## + CO Emissions Limit **Comment:** Many c ommenters ( 4673, 4712, 4836, 4989) object to estab lishing a mandatory NO X + CO NSPS emissions limit for EGUs at this time because of limited CO emissions data and the inadequate methodology used to determine the emissions limit. An analyses prepared by one commenter concludes that such a standard is unachievable for many EGUs much of the time. However, several of these commenters (4673, 4836, 4839, 5470) also state that a combined NO X and CO emissions limit could provide an advantage in terms of compliance flexibility . These commenters do not object to establishing an NO X + CO emission limit that EGU owner s/operators could chose to comply with as alternative to a NO X emissions limit

. Other c ommenter s (4715, 5715 ) support EPA establishing a mandato ry NO X + CO NSPS emissions limit for EGUs . However, one commenter states that EPA failed to explain why the Agency believes that a NO X + CO emissions limit of 1.2 lb/MWh for new sources reflects BSER systems of emission reduction , wh en it is at a significantly higher emissions rate than its NO X - only emissions limit proposed alternative. The NSPS emissions limit for NO X + CO should be lowered to reflect BSER , or at the very least, EPA must select a standard at the low end of the proposed range. Another commenter ( 17620) state s that a better option to adopting a combined limit for NO X + CO would be to set a sufficiently stringent CO standard that avoids poor combustion. Allowing inappropriately high CO levels will simply permit sources to use less effective SCR controls and emit higher levels of organic HAPs than would limits that are based on the level of NO X reduction and CO levels achievable by high efficiency SCRs controls. **Response:** While EPA believes that the limited data available supports the achievability of a combined NOx/CO standard in at least some circumstance, it does support the imposition of such a standard across the board. As a result , the combined NO X/CO standard will be provided as an alternative to the amended NO X standard. The alternative standard will be 1.1 lb/MWh, as that is the lowest standard that has been demonstrated for both pulverized coal and fluidized bed technologies. The combined standard is much more stringent than recent separate NO X and CO BACT permits . The majority of CO BACT standards are 0.10 lb/MMBtu or greater. This translates to an approximate CO emissions rate of 1.0 lb/MWh. With corresponding BACT NO X standards of 0.70 lb/MWh, this corresponds to an equivalent combined standard of 1.7 lb/MWh. **Co mment**  : One commenter (5210) state s that EPA must set the most protective NO X standard. EPA requested comment on whether the Agency should adopt a single NO X standard or a combined NO X + CO standard. While supporting EPA’s suggested benefits of such a combined standard, the commenter state s concern over if and how the Agency weighed the different health and environmental impacts of NO X and CO in determining the proposed combined standard. It appears the Agency weighed them equally, which the commenter believe s is not appropriate , given the greater health and environmental impacts of NO X and its contribution to ozone. While the commenter does not want CO emissions to significantly increase as a result of NO X controls, the commenter is concerned that the flexib ilities of a combined NO X + CO standard will provide for an ultimately more lenient NO X standard, resulting in fewer reductions. Therefore, the commenter recommend s that EPA at the least set the most stringent standard feasible for NO X , in order to protect public health and the environment from the harmful impacts of ozone, PM, and other NO X related emissions . Another commenter (5208) states that a combined NO X + CO standard potentially would allow higher NO X emissions that would not protect the more stringent nitrogen dioxide (NO 2 ) National Ambient Air Quality Standard (NAAQS). **Response:** EPA has concluded that the combined standard is sufficiently stringent. New facilities would at a minimum have to reduce emissions to the existing NO X standard in subpart Da, that was established in 2006 , toResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

17 comply with the standard. Therefore, this is not a relaxation of the existing requirements and would not result in increased NO X emissions. 

## 2.5.3 **N O**  **X** 

## Emissions Limit **Comment** : Several commenters (47 12, 4765, 4768, 4836, 5075 ) state that the proposed NO X emissions limit is not achievable on a nationwide basis, and the final rule should be revised upwards to reflect the actual levels of performance achievable

. In addition, a separate NO X emissions limit should be set for modified EGUs subject to the NSPS. Several commenters (4712, 4768) state that the methodology EPA used to select the proposed NO X emissions limit value does not sufficiently address variability in EGU fuel use, equipment design, and operation. One commenter (4768) includes their analysis of the data on which EPA based its determination that the proposed NO X emissions limit is achievable using BSER

. Based on this analysis, the commenter asserts that an appropriate NO X emiss ions limit is 0.83 lb/MWh for new units and 1.1 lb/MWh for modified or reconstructed units. The commenter states that the NO X emissions standard for modified units should be based on the performance of cell burners, wet

-bottom boilers, and cyclone fired EGUs. The commenter further notes that recent consent decrees for SCR

- equipped cyclone boilers require NOx emissions between 0.100 to 0.0120 lb/MMBtu. **Response:** The proposed standard of 0.70 lb/MWh has been demonstrated to be achievable by both pulverized co al and fluidized bed boilers burning various coal types. Since the CEMS data used in establishing the standards included long term data, various operating conditions and variability are inherently accounted for. In recognition of the difficulties of retrof itting certain modified facilities with combustion controls, the final NO X standard for modified facilities is 1.1 lb/MWh. **Comment** : One commenter ( 5077 ) state s that emissions during startup and shutdown periods have a particularly large impact on NO X emissions , even after taking into account the compensating effect of a 30

- day rolling average. Hence, these periods need to be excluded in the evaluation of compliance with the standard . Further, EPA should set a higher NO X NSPS standard for modified units , since older modified units typically have higher heat rates than new units. **Response:** Periods of startup and shutdown have not been filtered out of the CEMS data used to establish the standards, so there is no reason to separately evaluate those periods. The standard accounts for emissions typically being higher during periods of startup and shutdown and at the same time is sufficiently stringent that owners/operators need to minimize emissions during all periods to comply with the 30

- day standard. The final standard for modified units (1.1 lb/MWh) is based on CEMS data from facilities using subcritical steam conditions and accounts for the higher heat rates of older facilities. **Comment** : One commenter (4830) states that the proposed NO X NSPS of 0.70 lb/MWh appears to eliminate the further use of lignite coal for new EGUs. Section 111(a) requires EPA to explain the economic and energy impacts when establishing NSPS. Lignite coal is an abundant resource in the upper mid

-west and Gulf Coast areas and eliminati on of it as an energy source would have significant regional economic impacts. EPA has the discretionary authority to subcategorize EGUs such that lignite

- fired EGUs could have different NO X standards based on BSER for lignite. Thus, EPA should propose lignite NO X NSPS for new units. EPA has not demonstrated that non

- lignite

- fired units can meet the preferred 0.70 lb/MWh considering the inclusion of startup and shutdown periods into the compliance period. Accordingly, the alternative standard of 0.80 lb/MWh is more representative of what can be realistically achieved for non

- lignite units, and no level lower than that should be considered for the NO X NSPS for new units. **Response:** While the Oak Grove facilities use supercritical steam conditions, increasing the steam temperature and pressure to those used at the Weston 4 facility would reduce fuel use and emission rates by approximately 2.5%. In addition, upgrading the heating value of the lignite to 10,000 Btu/lb would improve the efficiency of the EGU by almost 4%. Designing either of these things into a new lignite

- fired EGU using the same control configuration as Oak Grove 1 would theoretically reduce the NO X emissions rate to less than the 0.70 lb/MWh amended NO X standard. The Sandow 5B facility is a subcritical lignite

- fired fluidized bed EGU and is presently operating below the combined NO X/CO standard. Furthermore, increasing the steam temperature and pressure to those used at theResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

18 Weston 4 facility would reduce fuel use and emission rates by approximately 5%. In addition, upgrading the heating value of the lignite to 10,000 Btu/lb would improve the efficiency of the EGU by almost 5%. Implementing both of these for a newly designed EGU using the same control configuration as Sandow 5B would the oretically reduce the NO X emissions rate to below the 0.70 lb/MWh amended NO X standard. Fluidized bed boilers are not limited in application since they are available in various sizes, the largest individual unit is 460 MW, and are able to utilize supercritical steam conditions. As described elsewhere in the response to comments, the 0.70 lb NO X/MWh is achievable for all of the primary coal (and petroleum coke)

- fired EGUs. 

## 2.6 **Com pliance**  **Requirements 2.6.1**  **Opacity Monitoring Comment**  : Many commenter s ( 471 2, 4836, 4989 ) support EPA’s proposal to allow affected EGUs using a PM continuous monitoring system ( CEMS ), a fabric filter bag leak detection system (BLDS), or an electrostatic precipitator ( ESP ) predictive model to be exempt ed from the existing requirement to install a continuous opacity monitoring system (COMS). **Response:** The final rule amendments include a provision allowing affected EGUs using a PM CEMS , a fabric filter BLDS, or an electrostatic precipitator ( ESP ) predictive model to be exempt ed from install ing a COMS. **Comment:** Several commenters (4673, 4836) support EPA ’s proposal to reduce the frequency of visible emissions testing for affected EGUs that are subject to an opacity standard, but are not required to use a COMS. The commenters further note that when EGUs are subject to state air permit requirements to conduct Method 9 visible opacity tests, visible emissions testing requirements under the NSPS are redundant and may conflict with the state requirements

. The commenter recommends that EPA add a provision in the rule explicitly allowing permitting authorities the discretion to waive any NSPS visible emissions testing as long as the state testing is at least as frequent. **Response:** All the boiler rules have been amended to allow the p ermitting authority the discretion to establish site specific monitoring plans for owners/operators of facilities burning fuels that typically result in low opacity. The frequency of Method 9 performance testing for owners/operators of facilities with some visible emissions, but with all 6

- minute readings of less than 5%, has been reduced from every 6 months to every 12 months. The frequency of opacity monitoring for owners/operators of facilities with higher opacity is unchanged. The additional testing fre quency for facilities with opacities of 5% and higher is required to adequately assure compliance with the opacity standard. 

## 2.6.2 PM Continuous Emission Monitoring **Comment:** Several commenters (4989, 5077) oppose removal of the option to use Method 19 of Appendix A when the PM CEMS minimum data availability conditions are not met. One commenter (5077) states that removal of the option to use Method 19 of Appendix A eliminates a credible option to provide data when monitor availability falls below a require d threshold. Without the Method 19 option, a source that does not meet the data availability requirements would have to obtain data using “other monitoring systems.” EPA provides no reason in the proposed rule for removing the Method 19 option. **Response:** The redline included the intended edits and the amendatory language was in error. The option to use Method 19 has not been removed in the final rule. **Comment:** Several commenters (4989, 5077) stated concern s about the ability of PM CEMS to meet the proposed 90% availability requirement on a 30

- day rolling average basis because of the limited number of installations of PM CEMS on EGUs

. One commenter ( 5077) requests that EP A consider using a 75% data availability requirement when validating a required reporting duration (i.e., 30 day rolling average). **Response:** We find the commenter's concern about a limited number of PM CEMS installations on utility units to be misplaced, as over 100 EGUs have instal led and are operating PM CEMS. As we are unaware of situations thatResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

19 have caused or may cause data availability from these units with PM CEMS to be below ninety percent, we find that that level is achievable in the field and that there is no need to lower it. **Comment:** One commenter (4989) states that for the PM CEMS missing data procedures EPA is proposing to replace references to “valid” data with the phrase “non

- out

- of

- control” data. Neither of these terms are defined in Subpart Da. **Response:** The part 63 definition for “out

- of

- control” has been added to subpart Da. This amendment improves consistency for reporting and reduces burden to the regulated community. 

## 2.6. **3 Electronic Reporting of Performance Test Data**  **Comment:** Several commenters (4712, 4836 , 4989, 5077 ) opposes EPA’s propos al specifying mandatory e lectronic reporting of PM CEMS performance data and Relative Accuracy Test A udit ( RATA) data to EPA’s Central Reporting Data Exchange (CDX) using the Electronic Reporting tool (ERT) . The commenter s state that this proposed requirement is unlawful, unsuppor ted, and incomprehensible for the following reasons: 1) EPA has not articulate d the purpose of the submission and reconcile d that with existing reporting requirements , 2) EPA has not use d appropriate terms to identify the data required to be submitted, 3) EPA has not submitted an Information Collection Request (ICR) and obtained Office of Management and Budget(OMB) approval as required by the Paperwork Reduction Act (PRA) for the data to be reported , and (4) EPA has not pro vided a reporting format compliant with EPA's Cross

- Media Electronic Reporting Regulation (CROMERR) requirements. **Response:** EPA strongly disagrees with the statement that the submittal of performance related data using the ERT is unlawful, unsupported, and incomprehensible. Section 114 of the Clean Air Act specifically allows EPA to require the submittal of emissions (and other environmental data) to develop regulations. In fact, in support of this rulemaking, there was an information collection request (ICR) that affected many facilities. If EPA had had these performance test data prior to the rulemaking, then an extensive ICR would not have been needed. We believe that requiring that such data be routinely su bmitted using the ERT will eliminate, or at least reduce, the need for such an extensive ICR in conjunction with future rulemaking. In answer to item 1 above, the purpose of requiring the submission of performance tests is to support the development of reg ulations. In addition, performance test data will be used to improve emissions factors, develop control strategies, determine rule effectiveness, and support other air pollution control activities. Assuming the commenters meant performance test reports, rather than performance data, disagrees with the statement that the requirements to submit performance test reports to EPA are unsupported. EPA has already required the use of the ERT for several information collection requests and has promulgated several other rules that require its use. Further, EPA as a whole has been working toward electronic submittal of environmental data and information; see, for example, the Risk Management Plan information required in 40 CFR part 68 and the Toxics Release Inventory requirements in the Emergency Planning and Community Right

-to

- Know Act of 1986. There are other common examples of electronic reporting, such as filing income tax , as well. Electronic reporting allows for easier submission and storage of data and will allow easier review and access for all stakeholders. If the commenters meant the submittal of the PM CEMS data, EPA also disagrees with the commenters. EPA has concluded that these data are important for determining the operation of the facility. These data are also important for determining compliance with this regulation. Thus, EPA is establishing a system to collect these data. EPA is not sure what the commenters intend in stating that the requirement are incomprehensible. We have concluded that the requirement is clear on its face and, f or the reasons stated above, electronic reporting of data is a very good solution, both for EPA and for industry, for the collection and review of air quality data. If the incomprehensible comment p ertains to the ERT, our response is that ERT has been used by many source testing companies and is steadily improving. EPA has worked very closely with the source samplers and industry to identify and correct most of the problems encountered with its use. In response to item 2, EPA is not sure what the commenters are asking. EPA developed the ERT with former source testing personnel and in conjunction with source testing companies. The model for the ERT was and is the performance test requirements in the parts 60 and 61 general provisions. The input of source testing companies was integral to the development of this tool and we are continuing to work closely with source samplers. Thus, common source testing terms are used in the ERT and most of the users of this tool have had little trouble in understanding what is required. The response to item 3Response to Comments on Proposed NSPS Amendments to Subparts D and Da

20 is that EPA will be accounting for ERT use in the ICR for the final regulation. EPA believes that requiring the use of this tool will not significantly increase any costs in the reporting of performance test data and will probably eventually result in a reduction in costs. EPA is aware that many source testing companies and most major facilities already use their own systems to gather performance test data electronic ally. EPA believes that the ERT works well and is ready for use. EPA also disagrees with the statement in item 4. EPA is working closely with the Office of Environmental Information to establish the procedures necessary to ensure that ERT submittals through EPA ’s Central Data Exchange are compliant with the Cross

- Media Electronic Reporting Regulation. EPA will have this process completed prior to the time when the ERT submittals are required. **Comment:** One commenter (4674), a state air regulatory agency, intends to continue to request affected owner or operators to submit hard copies of stack test reports to the State, in addition to EPA’s collection of stack testing data via the Electronic Reporting Tool (ERT), and therefore supports EPA’s preservation of related requirements in 40 CFR 60.8 and 60.11. The commenter believes that the stack test data reported must be considered along with additional, specific information for each source’s operations. This evaluation cannot be easily conducted with the limite d data reported in the ERT. The State believes that the stack test data submitted in the ERT, taken at face value, may be misleading unless the context in which the testing was completed is understood. Until the number and degree of source configuration and operation variables can be adequately accounted for and reported in one reporting tool, allowing the associated test data to be wholly considered, the State relies heavily upon the submission of written stack test reports. Thus, the commenter supports EPA’s preservation of the submittal of written performance testing reports to state agencies, and requests that EPA consider a way for states to report to EPA via the ERT that the test is not approvable or was not representative. **Response:** EPA agrees that th e State and Local Air Pollution Control Agencies (S/Ls) should be able to continue to require stack test reports to be submitted in the format that best suits their needs . However, EPA encourages S/Ls to consider requiring the submission of stack test dat a electronically as well and the ERT is a readily available tool for S/Ls use. In response to the comment that the stack test data taken at face value may be misleading, EPA disagrees. EPA believes that the data and information required to be submitted in the ERT is the same data and information that is included in written performance test reports and will allow for an adequate review of the stack test and its conduct. The ERT was designed using existing performance test reports. All the data in test report s is also clearly required in the ERT. EPA does believe that the S/Ls have the expertise and knowledge of their sources, such as operation variables and source configuration, and would generally be better able to evaluate stack test reports. Thus, we have designed the ERT , in conjunction with WebFIRE (the repository for ERT data), to allow for S/Ls to conduct a third

-party review of the performance test reports. Regarding the comment to have the S/Ls submit the data, EPA is designing the reporting to be sub mitted by the sources. Where the S/Ls have comments concerning a particular performance test, they need to discuss with the source and have the source resubmit the test report. We have concluded that having the source resubmit their performance test report electronically will eliminate the burden associated with tracking different versions of the test report in different formats

. 

### Comment: One commenter (4770) requests that the reporting requirements in rules Da, Db and Dc be amended to commence on January 1 , 2013 so that affected owners and operators have adequate time to familiarize themselves with the requirements and procedures for using the CDX and ERT. Until then, affected facilities should be allowed to continue to submit paper copies of test data to EPA. In addition, the reporting requirements should be changed to 90 days after completion of correlation and performance tests so that affected facilities have adequate time to gather required data and make adequate resources available to submit the data. **Response:** EPA does not agree that the electronic reporting of performance test data through the Central Data Exchange using the Electronic Reporting Tool (ERT) needs to be extended for one year because the ERT is difficult to use. EPA believes that the sou rce testing community, for the most part, has had plenty of experience in the past year using the ERT. EPA has also worked closely with the source testing community to understand and address their concerns with ease of use, so there is no need to extend the commencement date. We agree that it is appropriate to allow the required reports to be submitted 90 days after completion of correlation and performance tests. Among other things, this will provide time for owners/operators to familiarize themselves with ERT. Thus, we are extending the date for submitting the ERT report to 90 days.Response to Comments on Proposed NSPS Amendments to Subparts D and Da

21 

## 2.6.4 **Monitoring PM and Opacity Emissions from EGUs Using ESPs Comment:**  One commenter ( 17755 ) states the rule is not clear regarding how PM emissions will be monitored for EGUs using ESPs if and when the ESP is not running, e.g., during SSM or offline activities, and if the ESP is not running, commenter asks how these excess emissions will be detected using the ESP Predictive Model. The c ommenter states concerns that determining compliance with opacity and PM standards will be more complicated without some kind of continuous emission monitor in place. The commenter requests information and guidance on what constitutes an excess emission if there is no continuous emission monitor, and asks the following: how does the EPA anticipate that compliance with the emission limit be determined, would an inspector simply monitor and check all of the parameters established for the ESP Predictive Model, and if the ESP is operating out side the defined parameters is that considered an excess emission. **Response:** During periods of startup and shutdown the ESP predictive model would not apply and the owner/operator would be required to follow the specified work practice standards to minimi ze emissions. 

## 2.7 **Other Proposed Amendments**  **2.7.1 Rule Definitions**  **2.7.1. 1**  **Definition of “Affected Facility” Comment**  : One commenter ( 4836) stated that EPA’s rationale for proposing to revise the definition of “affected facility” by adding integrated combustion turbines and fuel cells is vague and ambiguous, and the existing definition should not be revised. Another (4766) stated that EPA should provide additional clari fication regarding the proposed expanded definition of “affected facility” under subpart Da to include “integrated” combustion turbines and fuel cells. Although discussed briefly in the preamble, the word “integrated” is still unclear and is not well

- defined in the rule. Also, although EPA suggests that its intent is to encourage and promote the use of such units, it is unclear how EPA’s proposed regulation would accomplish that goal. Without further explanation, the new definition of “affected facility” remains vague and ambiguous and should be eliminated. **Response:** The definition has been clarified to specify that “integrated” means the device either supplies useful thermal output to the boiler or electrical output to power auxiliary equipment of the EGU. If the definition were not expanded to include integrated equipment, the intent of subpart Da could be circumvented by having auxiliary equipment provide steam to the EGU to increase the output of the EGU and decrease the corresponding output

based emissio ns rate without accounting for the emissions from the integrated equipment. 

### 2.7.1.2 Definition of “Gaseous Fuel” **Comment** : One commenter (5195) stated that EPA should clarify within subpart Da that the definition of “fossil fuel” does not include landfill gas, biogases or other materials such as engineered fuels that are produced from processing components of municipal solid waste. Because landfill gas and biogas are included under the proposed definition of “gaseous fuel,” and the term “gaseous fuel” is included in the definition of “fossil fuel,” there may be an ambiguity with respect to how these definitions relate to each other in implementing subpart Da. The commenter requests that EPA clarify the circumstances under which subpart Da may apply to gaseou s fuel firing, where such gaseous fuel is not a fossil fuel (for example, where a non

- fossil gaseous fuel is combusted in combination and/or alternately with a fossil

- fuel). **Response:** The definition of fossil fuel under subpart Da only includes fuels “created for the purpose of creating useful heat.’ Since landfill gas and other fuels derived from municipal solid waste are not derived for the purpose of creating useful heat they are not considered fossil fuels under subpart Da. The definition of gaseou s fuel includes these fuels strictly for circumstances when non

- fossil fuel gaseous fuels are burned in combination with fossil fuels to determine the appropriate monitoring requirements. 

### 2.7.1.3 **Definition of “**

**IGCC Electric Utility Steam Generating Unit ”**  **Comment** : One commenter ( 4836 ) stated that EPA’s proposed revised definition of “IGCC Electric Utility Steam Generating Unit” should be reworded to read “The Administrator may waive the 50 percent solid

- derived fuelResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

22 requirement during periods of the gasific ation system construction, startup and commissioning, shutdown or repair.” Adding startup and commissioning would provide the EPA Administrator with additional authority to resolve any regulatory problems associated with the construction and initial operations of an IGCC EGU . Adding shutdown would allow an operator to combust natural gas for safety reasons during shutdown. **Response:** The definition has been amended as suggested. 

### 2.7.1.4 Definition of “Natural Gas” **Comment** : One commenter ( 4836 ) notes that the proposed Subpart D definition of” natural gas” , and the existing definitions of “natural gas” in 40 CFR 60 subparts Da, Db, and Dc, are slightly different from the definition of “natural gas” in Part 75. Another commenter (5749) stated that the definitions of “natural gas” used for the NSPS are different from the proposed definition of “natural gas” for the EGU NESHAP. The commenters recommend that EPA use this NSPS amendment rulemaking to make the definitions consistent in all of the rules to avoid confusion and unintended results. **Response:** In an effort to make the definitions as consistent as possible, the definition of “natural gas” under the NSPS has been amended as follows: i) “maintains a gaseous state under ISO conditions ” has been added; ii) the heating value range has been amended to 950 to 1,100 Btu/scf ; iii) a statement that natural gas does not include

“ any gaseous fuel produced in a process which might result in highly variable sulfur content or heating value ,” has been added; and , iv) a provision that the “maximum sulfur content is 20 grains per 100 standard cubic feet” h as been added. The definition for industrial sources has historically included liquefied petroleum gas and will continue to do so. However, it will be removed for subpart Da affected EGUs to make it more consistent with that used in part 75. 

### 2.7.1.5 Definition of “Petroleum Coke” **Comment** : Several commenters (4765, 4836 ) object to including petroleum coke in the definition of “coal” for purposes of NSPS subpart Da. Reasons cited by the commenters are 1) EPA acknowledged in its NSPS Subpart Y rulemaking that petroleum coke “is a by

-product residual from the thermal cracking of heavy residual oil during the petroleum refining process,” ( 74 F R 25,304, 25,316/1 ), and therefore is not coal at all ; and a s a result, the nature of the analysis required for setting NSPS would be different for petroleum coke as compared to coal ; 2) EPA has failed to provide emissions data as to whether EPA’s proposed NSPS for PM, NO X or SO 2 are achievable when petroleum coke is burned in a EGU , either during periods of normal operation or during periods of startup and shutdown. **Response:** When subpart Da was originally pro mulgated , petroleum coke was not as commonly used in utility boi lers. Subsequently, when EPA finalized the industrial boiler NSPS, subpart Db, petroleum coke was recognized as a valuable fuel that has characteristics similar to coal and was therefore included in the definition of coal. From analysis of emissions data f rom facilities burning petroleum coke EPA has concluded that EGUs burning petroleum coke are able to achieve the amended criteria pollutant standards for coal

- fired units

. The Northside 1A and 1B EGUs and the Manitowoc 9 petroleum coke

- fired EGUs are achieving the PM standard, the AES Deepwater petroleum coke

- fired EGU is achieving the NO X standard, and the Northside 1A facility is achieving the combined NO X + CO standard. While none of the petroleum coke

- fired EGUs are achieving the amended SO 2 standard, the SO 2 technology is directly transferrable and other facilities burning high sulfur fuels have demonstrated that 97% reduction in potential SO 2 emissions is achievable. Furthermore, the recent permit for the proposed Las Brisas Energy Center indicates that the amended NO X , SO 2 , and PM standards are achievable for a new petroleum coke

- fired EGU

. The proposed Las Brisas Energy Center would burn petroleum coke in a fluidized bed using subcritical steam conditions. The permit conditions for NO X and SO 2 are 0.070 lb/MMBtu and 0.114 lb/MMBtu respectively. The gross EGU efficiency would only have to be 34% (achievable using subcritical steam conditions) and 38% (achievable with supercritical steam conditions) to comply with the amended NO X and SO 2 standards, respectively. In addition, based on the sulfur content of the petroleum coke, the SO 2 control is designed to control over 97% of the potential SO 2 emissions.Response to Comments on Proposed NSPS Amendments to Subparts D and Da

23 

## 2.7.2 General Duty **Comment** : One commenter (4836 ) stated that EPA’s proposal to add to Subpart Da a provision imposing a “general duty to minimize emissions” is neither necessary nor appropriate. Subpart D a facilities already are subject to the general duty under 40 CFR 60.11(d). **Response:** EPA agrees that it is not necessary to include a specific provision imposing a “general duty to minimize emissions” in Subpart Da for the reason the commenter articulates. The provision has, therefore, been removed. 

## 2.7.3 Affirmative Defense Provisions **Comment:** One commenter (5210) stated that EPA’s prop osed inclusion of the “affirmative defense” for malfunctions is unlawful and contravenes the CAA. The commenter states that the CAA clearly sets forth how the courts are to assess civil penalties, whether the case is brought by a citizen or EPA . 42 U.S.C. § 7413(e). By allowing an affirmative defense in the case of malfunction, EPA goes directly against two expressed intentions of Congress: 1) the burden it places on citizens makes it less likely that they will enforce the CAA, see, e.g., Pennsylvania v. De l. Valley Citizens' Council for Clean Air, 478 U.S. 546, 560 (1986);and 2) several of the factors at issue in the affirmative defense undercut Congress's intent that citizen suit enforcement should avoid re

delving into "technological or other considerations, "NRDC v. Train, 510 F.2d 692, 700 (D.C. Cir. 1974). Both result from the technical burden EPA imposes on citizens with the affirmative defense, and both render the defense impermissible. In addition to these problems, there is simply no need for an aff irmative defense to penalties to be written into the regulations. EPA has discretion to decide what cases to prosecute, to consider settlements, and to request civil penalties in a case

-by

- case manner, as long as it acts consistent with the CAA to protect clean air as its top priority, see U.S.C. § 7401. If EPA has the authority to promulgate any type of “affirmative defense”, then the commenter made specific recommendations for the provisions of such “affirmative defense”. Several commenters (4714, 4770, 4 830, 4997) stated that the proposed “affirmative defense” provisions to be added to subpart Da need clarifications, are vague or contradictory, and impose requirements that the defense will be entirely useless as a practical matter. Some of the nine requirements that EPA proposed be met in order for a facility to claim an affirmative defense for a malfunction are unreasonable, difficult to demonstrate, and subject to varying interpretation. EPA should revise the affirmative defense provisions in the rule so that the requirements are meaningful to implement

. The commenters provided specific recommended changes to the proposed rule language to address these issues. Another commenter (17975) states that EPA has not determined whether some emission control technologies are prone to malfunctions, or explained why EGUs that rely on such equipment should be entitled to an affirmative defense when it breaks down. Requiring government agencies to evaluate and rebut affirmative defenses on a case by case basis is impractical and has proved ineffective. **Response:** EPA is finalizing emission standards that apply at all times, including during periods of malfunction. For malfunctions, the EPA is finalizing the proposed affirmative defense language for exceedances of t he numerical emission limits that are caused by malfunctions. As EPA explained in the preamble to the proposed rule, EPA recognizes that even equipment that is properly designed and maintained can fail and that such failure can cause an exceedance of the relevant emission standard. The EPA included an affirmative defense in the final rule in an attempt to balance a tension, inherent in many types of air regulation, to ensure adequate compliance while simultaneously recognizing that despite the most diligent of efforts, emission limits may be exceeded under circumstances beyond the control of the source. With respect to the Affirmative Defense and the comment that the provisions are vague or contradictory, the EPA’s view is that the affirmative defense is consistent with CAA section the EPA believes that courts are well equipped and often do evaluate and apply the type of criteria set forth is the affirmative defense. Many of the conditions were modeled after the conditions of the affirmative defense in EPA’s SIP SSM policy, which several states have adopted into their SIPs. (See, e.g., State Implementation Plans: Policy Regarding Excessive Emissions During Malfunctions, Startup, and Shutdown (Sept. 20, 1999); Policy on Excess Emissions During Startup, Shutdown, Maintenance, and Malfunctions (Feb. 15, 1983)). We do not have any indication that parties to enforcement proceedings have had any significant difficulties applying the terms of these SIP affirmative defenses. In addition, EPA’s view is that use of cons istent terms in establishing affirmative defense regulationsResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

24 and policies across various CAA programs will promote consistent implementation of those rules and policies. The affirmative defense does not require a facility to prove its innocence rather than requiring an enforcement authority to prove a violation of the CAA or change the burden of proof with respect to establishing a violation. The affirmative defense applies to penalties and thus is only utilized where a violation has been established. The burden of proof remains with the plaintiff in an enforcement action. See, e.g., 40 C.F.R. 22.24. If a violation has been established and a source wishes to assert the affirmative defense with respect to penalties, the source does bear the burden of establis hing that the elements of the affirmative defense have been met. This burden

- shifting is appropriate because the source is in a better position to determine the facts required to establish the defense. See, e.g., Arizona Pub. Serv. Co. v. EPA, 562 F.3d 111 6, 1120, 1129

- 30 (10th Cir. 2009) (rejecting industry challenge to EPA’s use of an affirmative defense to address excess emissions during malfunction events.). **Comment:** One commenter (4714) states that the proposed rules should be revised to enable EPA to allow state rules for affirmative defense that are EPA

- approved as part of a state implementation plan (SIP) to be used in lieu of the federal procedures. This flexibility would eliminate duplicative or potentially even conflicting requirements for both st ate agencies and regulated entities. **Response:** As a general matter, state SIP provisions do not apply in the context of an EPA promulgated NSPS. States can, and in fact are encouraged to, take delegation of the authority to implement and enforce the requirements of NSPS; however, in such circumstances, it is still the provisions of the NSPS that apply, not EPA

approved SIP provisions. EPA, therefore, concludes that inclusion of the Affirmative Defense in the NSPS is appropriate

. **Comment:** One commenter (4714) states that an initial notification should be required if an affected owner/operator wishes to claim an affirmative defense and the proposed rules should specify notification by telephone or facsimile. An electronic reporting mechanism should be allowed for this initial notification. However, telephone notifications should not be allowed because such notifications are difficult to verify and enforce. At a minimum, electronic notification that complies with EPA’s Cross

- Media Electronic Reporting Regulation (CROMERR) standards could provide for quick and durable reporting that may be relied upon for investigative and enforcement purposes. **Response:** The EPA accepts documents in electronic format, as long as the format is compatible with the requirements of the standards. For the affirmative defense provis ions, the owner or operator of a facility experiencing an exceedance of its emission limit(s) during a malfunction must notify the Administrator by telephone or facsimile (FAX) transmission as soon as possible, but no later than two business days after the initial occurrence of the malfunction, or if it is not possible to determine within two business days after the malfunction caused or contributed to an exceedance, no later than two business days after the owner or operator knew or should have known that the malfunction caused or contributed to an exceedance, but, in no event later than two business days after the end of the averaging period. The written reports required to demonstrate that the affirmative defense provisions have been met and requests for an extension of the deadline for these reports may also be submitted electronically. EPA has conlcuded that notification by telephone is appropriate since that notification must by followed by submission of a written report demonstrating that the affirmative defense provisions, including the notification requirement, have been met. 

## 2.7.4 Subpart Da **Mercury Provisions Comment**  : Several commenters (4836, 5715) state that it is appropriate to remove the applicable mercury emissions standards provisions vacated by a federal court ruling from the NSPS under 40 CFR 60 subpart Da). **Response:** The provisions have been removed. In addition, the amendments to subpart B that occurred as part of the Clean Air Mercury Rule have also been removed. 

## 2.7.5 **Removal of Reference s to 30** 
**- Day Rolling Averages**  **Comment** : One commenter (4836 ) stated that EPA’s proposed removal of references to 30

- day rolling averages in Subpart Da provisions establishing emission limitations and the addition of new provisions stating that compliance with emission limits in various sections “are determined on a 30

- day rolling average basis” does notResponse to Comments on Proposed NSPS Amendments to Subparts D and Da

25 appear to be intended to change the averaging time of any provision, but could cause confusion and should be better explained. **Response:** The revisions are only intended to make the rules easier to read and are not intended to change any of the existing provisions. 

## 2.7.6 Deletion of Obsolete Provision References in Rule **Comment** : One commenter ( 4698 ) supports EPA proposal to delete “emergency condition” requirements for the SO 2 standard exemption, references to percent reductions for NO X and PM, references to the term “solvent refined coal , ” and the existing commercial demonstration permit references. **Response:** The provisions have been removed 

## 2.7.7 Proposed R**ule Language Corrections and Clarifications Comment**  : One commenter ( 4698 ) states that in § 60.48Da(k)(1)(i) the term “O sg” in Equation 2 should be defined as “Average hourly gross energy output from electric utility steam generating unit” to be consistent with the rule’s definitions. **Response:** A “steam generating unit” is a subset of an “electric utility steam generating” and EPA has concluded that the suggested change is not necessary

.Response to Comments on Proposed NSPS Amendments to Subparts Db and Dc

26 

## 3. Response to Comments on Pr**oposed NSPS Amendments to Subparts**  **Db and Dc 3.1**  **Definition of “Distillate Oil”**  **Comment** : Several commenters (4698, 4770, 4841 ) support EPA’s proposal to expand the definition of “Distillate oil” in both 40 CFR 60 subparts Db and Dc to include biodiesel and kerosene because it is appropriate to have the same requirements for units burning biodiesel or kerosene as those units firing distillate fuel oil. One commenter ( 5749 ) requested that EPA explain why the definition for “distillate oil” in 40 CFR 60 subpart Db of the NSPS includes a limitation on the weight percent nitrogen, while the proposed definition for “distillate oil” in the EGU NESHAP does not. **Response:** The definition of distillate oil has been amended as proposed. When the industrial boiler NSPS was originally promulgated , certain provisions in the NSPS assume d low fuel NO X formation and that requires low fuel nitrogen content. This is not necessary for purposes of the EGU NESHAP. 

## 3.2 Exemption of Steam Generating Units Subject to Other NSPS **Comment** : One commenter (4841) su pports EPA’s proposal to i) exempt owners and operators of affected facilities subject to 40 CFR 60 subpart Eb (standards of performance for large municipal waste combustors ( MWCs) and 40 CFR 60 subpart CCCC (standards of performance for commercial and ind ustrial solid waste incineration) from 40 CFR part 60, subpart Da ; ii) exempt owners/operators of affected facilities subject to 40 CFR part 60, subpart BB (standards of performance for Kraft pulp mills) from the PM standards under subpart Db ; and , iii) ex empt owners/operators of fuel gas combustion devices subject to 40 CFR 60 subpart Ja (standards of performance for petroleum refineries) from the SO 2 standard under 40 CFR 60 subpart Db. **Response:** The exemptions are included in the final rule. 

## 3.3 **Applicab ility to Temporary Boilers**  **Comment:** One commenter (4766) stated that EPA appears to suggest that separate NSPS requirements should apply to temporary boilers that are on

- site for 30 days or less. However, temporary boilers, especially those brought on

- site on skids or trucks for construction projects, are not stationary equipment and therefore do not fall under NSPS. In any event, even if such temporary sources could be considered “stationary,” 30 days is not enough time to implement the NSPS. **Response:** Since temporary boilers are not self propelled they are considered stationary facilities and subject to the applicable NSPS. In recognition of the special considerations of temporary boilers the final rule exempts temporary boiler s that burn natural gas and/or low sulfur distillate oil from the NSPS. The definition added to 40 CFR 60 subparts Db and Dc is as follows: Temporary boiler means any generating unit that combusts natural gas and/or distillate oil with a potential SO 2 emissions rate of 26 ng/J (0.060 lb/MMBtu) or less , and that is designed to, and is capable of, being carried or moved from one location to another by means of, for example, wheels, skids, carrying handles, dollies, trailers, or platforms. A steam generating unit is not a temporary boiler if any one of the following conditions exists: (1) The equipment is attached to a foundation. (2) The steam generating unit or a replacement remain s at a location for more than 180 consecutive days

. Any temporary boiler t

hat replaces a temporary boiler at a location and performs the same or similar function will be included in calculating the consecutive time period. (3) The equipment is located at a seasonal facility and operates during the full annual operating period of the seasonal facility, remains at the facility for at least 2 years, and operates at that facility for at least 3 months each year.Response to Comments on Proposed NSPS Amendments to Subparts Db and Dc

27 (4) The equipment is moved from one location to another in an attempt to circumvent the residence time requirements of this definition. The requirement to limit fuel to inherently cleaner burning fuels minimizing emissions while providing flexibility to the regulated community. 

## 3.4 Site
**- Specific Monitoring Plan**  **Comment:** One commenter (4674) requests that EPA provide further guidance on the “written site

- specific monitoring plan approved by the permitting authority,” under 40 CFR 60.47c(h). Specifically, commenter requests that EPA allow permitting authorities to authorize less stringent opacity or other monitoring requirements than identified in the rule. For example, a permitting agency could require affected owners and operators to conduct opacity testing only upon using a fuel for operational reasons rather than for compliance demonstrations. Further, a permitting agency could specify that each periodically required Method 9 does not have to adhere to the 40 CFR part 60 notification and reporting requirements associated with performance tests found in §60.8 and §60.11, but rather the affected owner or operator would be required to submit any deviations with the excess emissions report required under §60.48c(c). **Response:** There are no specific requirements in § 60.47c(h). The permitting authority for the owner/operator of the affected steam generating unit determines appropriate “procedures and criteria for establishing and monitoring specific parameters for the affected facility indicative of compliance with the opacity standard on a site specific basis . The source specific requirements could be as described in the comment as long as the permitting authority has determined they are appropriate for a specific affected facility. 

## 3.5 **Opacity Monitoring Comment:**  One commenter (4674) , a state air pollution control agency, recommends that EPA consider removing the requirement to com

plete subsequent Method 9 opacity performance tests after the initial performance test is completed, if the affected owner or operator is able to show in the initial reading that the opacity complies with the standard. It is the experience of the commenter that subsequent opacity readings for sources which have not exceeded the standard are onerous and may actually discourage good air pollution control practices. Alternately, the State suggests that EPA consider expanding the extension associated with propo sed changes to 40 CFR 60.47c(a)(1)(i). EPA proposed a change to allow affected owners and operators to extend the time frame to complete a Method 9 performance test from a minimum of every 12 months for sources where the initial performance test showed that there were no visible emissions. EPA proposes to allow those sources to either repeat the performance test every month or within 45 days of using a fuel with an opacity standard. Without the latter option, sources which primarily combust natural gas are often required to undergo a special startup using diesel fuel solely to satisfy the current compliance requirement to complete a Method 9 performance test every 12 months. As proposed, those sources will now only be required to complete a Method 9 performance test within 45 days of using diesel fuel, which will be dependent on the sources’ operational needs and not a compliance requirement. The State is in agreement with EPA’s proposed revision to 40 CFR 60.47c(a)(1)(i). However, this proposed extension is only available to facilities that have no visible emissions observed during the initial 60 minute Method 9 performance test. Pursuant to 40 CFR 60.47c(a)(1)(ii

- iv), sources which have any 6

- minute opacity average greater than 0% must conduct another Method 9 performance test for compliance purposes in the near term (every 6 months, 3 months, or more frequently). It is the commenter’s experience that all boilers running on diesel experience some degree of opacity during operation, which typically subsides quickly. At least one 6

- minute opacity average is likely to exceed 0%. For many of the State’s sources, the primary fuel used is natural gas, and diesel fuel is used only as a backup. Because these sources are likely to have at least one 6

- minute opacity average greater than 0% while using diesel fuel, they are required to repeat the Method 9 performance test even if they have ceased using diesel fuel in the interim. Repeating this performance test requires the affected owner or operator to shut down the boil er and restart using diesel fuel, only to shut down once again to restart using natural gas. It is the State’s experience that, left to the operational needs of the source, a boiler may only utilize diesel fuel once every few years as opposed to the compli ance requirement to use diesel fuel every few months. It appears that the 45

- day allowance, while intending to limit unnecessary opacity monitoring for sources with no visible emissions, was not extended to sources which may have some visible emissions during operation.Response to Comments on Proposed NSPS Amendments to Subparts Db and Dc

28 Therefore, such sources are required to regularly shutdown their equipment and restart on diesel just to complete the necessary opacity readings. The State suggests that either EPA extend the 45

- day allowance to 40 CFR 60.47c(a)(1)(ii

- iv), o r that a permitting agency may authorize an alternative opacity monitoring schedule by means of the site

- specific monitoring plan as discussed §60.47c(h). **Response:** Under subpart Dc § 60.47c(h), state permitting authorities have the ability to develop an alternate opacity monitoring plan to alleviate the above concerns. To minimize burden, the 45 day testing allowance has been added to all subparts.