Rule2024-09148
National Emission Standards for Hazardous Air Pollutants: Coal- and Oil-Fired Electric Utility Steam Generating Units Review of the Residual Risk and Technology Review
Primary source
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Published
May 7, 2024
Effective
July 8, 2024
Issuing agencies
Environmental Protection Agency
Abstract
This action finalizes amendments to the national emission standards for hazardous air pollutants (NESHAP) for the Coal- and Oil- Fired Electric Utility Steam Generating Units (EGUs) source category. These final amendments are the result of the EPA's review of the 2020 Residual Risk and Technology Review (RTR). The changes, which were proposed under the technology review in April 2023, include amending the filterable particulate matter (fPM) surrogate emission standard for non-mercury metal hazardous air pollutants (HAP) for existing coal- fired EGUs, the fPM emission standard compliance demonstration requirements, and the mercury (Hg) emission standard for lignite-fired EGUs. Additionally, the EPA is finalizing a change to the definition of "startup." The EPA did not propose, and is not finalizing, any changes to the 2020 Residual Risk Review.
Full Text
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[Federal Register Volume 89, Number 89 (Tuesday, May 7, 2024)]
[Rules and Regulations]
[Pages 38508-38593]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-09148]
[[Page 38507]]
Vol. 89
Tuesday,
No. 89
May 7, 2024
Part IV
Environmental Protection Agency
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40 CFR Part 63
National Emission Standards for Hazardous Air Pollutants: Coal- and
Oil-Fired Electric Utility Steam Generating Units Review of the
Residual Risk and Technology Review; Final Rule
Federal Register / Vol. 89 , No. 89 / Tuesday, May 7, 2024 / Rules
and Regulations
[[Page 38508]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 63
[EPA-HQ-OAR-2018-0794; FRL-6716.3-02-OAR]
RIN 2060-AV53
National Emission Standards for Hazardous Air Pollutants: Coal-
and Oil-Fired Electric Utility Steam Generating Units Review of the
Residual Risk and Technology Review
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: This action finalizes amendments to the national emission
standards for hazardous air pollutants (NESHAP) for the Coal- and Oil-
Fired Electric Utility Steam Generating Units (EGUs) source category.
These final amendments are the result of the EPA's review of the 2020
Residual Risk and Technology Review (RTR). The changes, which were
proposed under the technology review in April 2023, include amending
the filterable particulate matter (fPM) surrogate emission standard for
non-mercury metal hazardous air pollutants (HAP) for existing coal-
fired EGUs, the fPM emission standard compliance demonstration
requirements, and the mercury (Hg) emission standard for lignite-fired
EGUs. Additionally, the EPA is finalizing a change to the definition of
``startup.'' The EPA did not propose, and is not finalizing, any
changes to the 2020 Residual Risk Review.
DATES: This final rule is effective on July 8, 2024. The incorporation
by reference of certain material listed in the rule was approved by the
Director of the Federal Register as of April 16, 2012.
ADDRESSES: The U.S. Environmental Protection Agency (EPA) has
established a docket for this action under Docket ID No. EPA-HQ-OAR-
2018-0794. All documents in the docket are listed on the <a href="https://www.regulations.gov">https://www.regulations.gov</a> website. Although listed, some information is not
publicly available, e.g., Confidential Business Information or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the internet
and will be publicly available only in hard copy form. Publicly
available docket materials are available either electronically through
<a href="https://www.regulations.gov">https://www.regulations.gov</a>, or in hard copy at the EPA Docket Center,
WJC West Building, Room Number 3334, 1301 Constitution Ave. NW,
Washington, DC. The Public Reading Room hours of operation are 8:30
a.m. to 4:30 p.m. Eastern Standard Time (EST), Monday through Friday.
The telephone number for the Public Reading Room is (202) 566-1744, and
the telephone number for the EPA Docket Center is (202) 566-1742.
FOR FURTHER INFORMATION CONTACT: For questions about this final action
contact Sarah Benish, Sector Policies and Programs Division (D243-01),
Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, P.O. Box 12055, Research Triangle Park, North
Carolina 27711; telephone number: (919) 541-5620; and email address:
<a href="/cdn-cgi/l/email-protection#680a0d06011b00461b091a0900280d1809460f071e"><span class="__cf_email__" data-cfemail="9dfff8f3f4eef5b3eefceffcf5ddf8edfcb3faf2eb">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Preamble acronyms and abbreviations. We use multiple acronyms and
terms in this preamble. While this list may not be exhaustive, to ease
the reading of this preamble and for reference purposes, the EPA
defines the following terms and acronyms here:
APH air preheater
Btu British Thermal Units
CAA Clean Air Act
CEMS continuous emission monitoring system
EGU electric utility steam generating unit
EIA Energy Information Administration
ESP electrostatic precipitator
FF fabric filter
FGD flue gas desulfurization
fPM filterable particulate matter
GWh gigawatt-hour
HAP hazardous air pollutant(s)
HCl hydrogen chloride
HF hydrogen fluoride
Hg mercury
Hg\0\ elemental Hg vapor
Hg\2+\ divalent Hg
HgCl<INF>2</INF> mercuric chloride
Hg<INF>p</INF> particulate bound Hg
HQ hazard quotient
ICR Information Collection Request
IGCC integrated gasification combined cycle
IPM Integrated Planning Model
IRA Inflation Reduction Act
lb pounds
LEE low emitting EGU
MACT maximum achievable control technology
MATS Mercury and Air Toxics Standards
MMacf million actual cubic feet
MMBtu million British thermal units of heat input
MW megawatt
NAICS North American Industry Classification System
NESHAP national emission standards for hazardous air pollutants
NO<INF>X</INF> nitrogen oxides
NRECA National Rural Electric Cooperative Association
OMB Office of Management and Budget
PM particulate matter
PM<INF>2.5</INF> fine particulate matter
PM CEMS particulate matter continuous emission monitoring systems
REL reference exposure level
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
RIN Regulatory Information Number
RTR residual risk and technology review
SC-CO<INF>2</INF> social cost of carbon
SO<INF>2</INF> sulfur dioxide
TBtu trillion British thermal units of heat input
tpy tons per year
UMRA Unfunded Mandates Reform Act
WebFIRE Web Factor Information Retrieval System
Background information. On April 24, 2023, the EPA proposed
revisions to the Coal- and Oil-Fired EGU NESHAP based on our review of
the 2020 RTR. In this action, we are finalizing revisions to the rule,
commonly known as the Mercury and Air Toxics Standards (MATS). We
summarize some of the more significant comments regarding the proposed
rule that were received during the public comment period and provide
our responses in this preamble. A summary of all other public comments
on the proposal and the EPA's responses to those comments is available
in National Emission Standards for Hazardous Air Pollutants: Coal- and
Oil-Fired Electric Utility Steam Generating Units Review of the
Residual Risk and Technology Review Proposed Rule Response to Comments,
Docket ID No. EPA-HQ-OAR-2018-0794. A ``track changes'' version of the
regulatory language that incorporates the changes in this action is
available in the docket.
Organization of this document. The information in this preamble is
organized as follows:
I. General Information
A. Executive Summary
B. Does this action apply to me?
C. Where can I get a copy of this document and other related
information?
D. Judicial Review and Administrative Reconsideration
II. Background
A. What is the authority for this action?
B. What is the Coal- and Oil-Fired EGU source category and how
does the NESHAP regulate HAP emissions from the source category?
C. Summary of the 2020 Residual Risk Review
D. Summary of the 2020 Technology Review
E. Summary of the EPA's Review of the 2020 RTR and the 2023
Proposed Revisions to the NESHAP
III. What is included in this final rule?
A. What are the final rule amendments based on the technology
review for the Coal- and Oil-Fired EGU source category?
B. What other changes have been made to the NESHAP?
C. What are the effective and compliance dates of the standards?
[[Page 38509]]
IV. What is the rationale for our final decisions and amendments to
the filterable PM (as a surrogate for non-Hg HAP metals) standard
and compliance options from the 2020 Technology Review?
A. What did we propose pursuant to CAA Section 112(d)(6) for the
Coal- and Oil-Fired EGU source category?
B. How did the technology review change for the Coal- and Oil-
Fired EGU source category?
C. What key comments did we receive on the filterable PM and
compliance options, and what are our responses?
D. What is the rationale for our final approach and decisions
for the filterable PM (as a surrogate for non-Hg HAP metals)
standard and compliance demonstration options?
V. What is the rationale for our final decisions and amendments to
the Hg emission standard for lignite-fired EGUs from review of the
2020 Technology Review?
A. What did we propose pursuant to CAA section 112(d)(6) for the
lignite-fired EGU subcategory?
B. How did the technology review change for the lignite-fired
EGU subcategory?
C. What key comments did we receive on the Hg emission standard
for lignite-fired EGUs, and what are our responses?
D. What is the rationale for our final approach and decisions
for the lignite-fired EGU Hg standard?
VI. What is the rationale for our other final decisions and
amendments from review of the 2020 Technology Review?
A. What did we propose pursuant to CAA section 112(d)(6) for the
other NESHAP requirements?
B. How did the technology review change for the other NESHAP
requirements?
C. What key comments did we receive on the other NESHAP
requirements, and what are our responses?
D. What is the rationale for our final approach and decisions
regarding the other NESHAP requirements?
VII. Startup Definition for the Coal- and Oil-Fired EGU Source
Category
A. What did we propose for the Coal- and Oil-Fired EGU source
category?
B. How did the startup provisions change for the Coal- and Oil-
Fired EGU source category?
C. What key comments did we receive on the startup provisions,
and what are our responses?
D. What is the rationale for our final approach and final
decisions for the startup provisions?
VIII. What other key comments did we receive on the proposal?
IX. Summary of Cost, Environmental, and Economic Impacts and
Additional Analyses Conducted
A. What are the affected facilities?
B. What are the air quality impacts?
C. What are the cost impacts?
D. What are the economic impacts?
E. What are the benefits?
F. What analysis of environmental justice did we conduct?
X. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 14094: Modernizing Regulatory Review
B. Paperwork Reduction Act (PRA)
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations and Executive Order 14096: Revitalizing Our Nation's
Commitment to Environmental Justice for All
K. Congressional Review Act (CRA)
I. General Information
A. Executive Summary
1. Background and Purpose of the Regulatory Action
Exposure to hazardous air pollutants (``HAP,'' sometimes known as
toxic air pollution, including Hg, chromium, arsenic, and lead) can
cause a range of adverse health effects including harming people's
central nervous system; damage to their kidneys; and cancer. These
adverse effects can be particularly acute for communities living near
sources of HAP. Recognizing the dangers posed by HAP, Congress enacted
Clean Air Act (CAA) section 112. Under CAA section 112, the EPA is
required to set standards based on maximum achievable control
technology (known as ``MACT'' standards) for major sources \1\ of HAP
that ``require the maximum degree of reduction in emissions of the
hazardous air pollutants . . . (including a prohibition on such
emissions, where achievable) that the Administrator, taking into
consideration the cost of achieving such emission reduction, and any
nonair quality health and environmental impacts and energy
requirements, determines is achievable.'' 42 U.S.C. 7412(d)(2). The EPA
is further required to ``review, and revise'' those standards every 8
years ``as necessary (taking into account developments in practices,
processes, and control technologies).'' Id. 7412(d)(6).
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\1\ The term ``major source'' means any stationary source or
group of stationary sources located within a contiguous area and
under common control that emits or has the potential to emit
considering controls, in the aggregate, 10 tons per year or more of
any hazardous air pollutant or 25 tons per year or more of any
combination of hazardous air pollutants. 42 U.S.C. 7412(a)(1).
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On January 20, 2021, President Biden signed Executive Order 13990,
``Protecting Public Health and the Environment and Restoring Science to
Tackle the Climate Crisis'' (86 FR 7037; January 25, 2021). The
executive order, among other things, instructed the EPA to review the
2020 final rule titled National Emission Standards for Hazardous Air
Pollutants: Coal- and Oil- Fired Electric Utility Steam Generating
Units--Reconsideration of Supplemental Finding and Residual Risk and
Technology Review (85 FR 31286; May 22, 2020) (2020 Final Action) and
to consider publishing a notice of proposed rulemaking suspending,
revising, or rescinding that action. The 2020 Final Action included two
parts: (1) a finding that it is not appropriate and necessary to
regulate coal- and oil-fired EGUs under CAA section 112; and (2) the
RTR for the 2012 MATS Final Rule.
The EPA reviewed both parts of the 2020 Final Action. The results
of the EPA's review of the first part, finding it is appropriate and
necessary to regulate EGUs under CAA section 112, were proposed on
February 9, 2022 (87 FR 7624) (2022 Proposal) and finalized on March 6,
2023 (88 FR 13956). In the 2022 Proposal, the EPA also solicited
information on the performance and cost of new or improved technologies
that control HAP emissions, improved methods of operation, and risk-
related information to further inform the EPA's review of the second
part, the 2020 MATS RTR. The EPA proposed amendments to the RTR on
April 24, 2023 (88 FR 24854) (2023 Proposal) and this action finalizes
those amendments and presents the final results of the EPA's review of
the MATS RTR.
2. Summary of Major Provisions of the Regulatory Action
Coal- and oil-fired EGUs remain one of the largest domestic
emitters of Hg and many other HAP, including many of the non-Hg HAP
metals--including lead, arsenic, chromium, nickel, and cadmium--and
hydrogen chloride (HCl). Exposure to these HAP, at certain levels and
duration, is associated with a variety of adverse health effects. In
the 2012 MATS Final Rule, the EPA established numerical standards for
Hg, non-Hg HAP metals, and acid gas HAP emissions from coal- and oil-
fired EGUs. The EPA also established work practice standards for
emissions of organic HAP. To address emissions of non-Hg HAP
[[Page 38510]]
metals, the EPA established individual emission limits for each of the
10 non-Hg HAP metals \2\ emitted from coal- and oil- fired EGUs.
Alternatively, affected sources could meet an emission standard for
``total non-Hg HAP metals'' by summing the emission rates of each of
the non-Hg HAP metals or meet a fPM emission standard as a surrogate
for the non-Hg HAP metals. For existing coal-fired EGUs, almost every
unit has chosen to demonstrate compliance with the non-Hg HAP metals
surrogate fPM emission standard of 0.030 pounds (lb) of fPM per million
British thermal units of heat input (lb/MMBtu).
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\2\ The ten non-Hg HAP metals are antimony, arsenic, beryllium,
cadmium, chromium, cobalt, lead, manganese, nickel, and selenium.
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Pursuant to CAA section 112(d)(6), the EPA reviewed developments in
the costs of control technologies, and the effectiveness of those
technologies, as well as the costs of meeting a fPM emission standard
that is more stringent than 0.030 lb/MMBtu and the other statutory
factors. Based on that review, the EPA is finalizing, as proposed, a
revised non-Hg HAP metal surrogate fPM emission standard for all
existing coal-fired EGUs of 0.010 lb/MMBtu. This strengthened standard
will ensure that the entire fleet of coal-fired EGUs is performing at
the fPM pollution control levels currently achieved by the vast
majority of regulated units. The EPA further concludes that it is the
lowest level currently compatible with the use of PM CEMS for
demonstrating compliance.
Relatedly, the EPA is also finalizing a revision to the
requirements for demonstrating compliance with the revised fPM emission
standard. Currently, affected EGUs that do not qualify for the low
emitting EGU (LEE) program for fPM \3\ can demonstrate compliance with
the fPM standard either by conducting quarterly performance testing
(i.e., quarterly stack testing) or by using particulate matter (PM)
continuous emission monitoring systems (PM CEMS). PM CEMS confer
significant benefits, including increased transparency regarding
emissions performance for sources, regulators, and the surrounding
communities; and real-time identification of when control technologies
are not performing as expected, allowing for quicker repairs. After
considering updated information on the costs for quarterly performance
testing compared to the costs of PM CEMS and the measurement
capabilities of PM CEMS, as well as the many benefits of using PM CEMS,
the EPA is finalizing, as proposed, a requirement that all coal- and
oil-fired EGUs demonstrate compliance with the revised fPM emission
standard by using PM CEMS. As the EPA explained in the 2023 Proposal,
by requiring facilities to use PM CEMS, the current compliance method
for the LEE program becomes superfluous since LEE is an optional
program in which stack testing occurs infrequently, and the revised fPM
limit is below the current fPM LEE program limit. Therefore, the EPA is
finalizing, as proposed, the removal of the fPM LEE program.
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\3\ In order to qualify for fPM LEE status, an EGU must
demonstrate that its fPM emission rate is below 50 percent of
standard (or 0.015 lb/MMBtu) from quarterly stack tests for 3
consecutive years. Once a source achieves LEE status for fPM, the
source must conduct stack testing every 3 years to demonstrate that
its emission rate remains below 50 percent of the standard.
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Based on comments received during the public comment period, the
EPA is not removing, but instead revising the alternative emission
limits for the individual non-Hg HAP metals such as lead, arsenic,
chromium, nickel, and cadmium and for the total non-Hg HAP metals
proportional to the finalized fPM emission limit of 0.010 lb/MMBtu.\4\
Owners and operators of EGUs seeking to use these alternative standards
must request and receive approval to use a HAP metal continuous
monitoring system (CMS) as an alternative test method under 40 CFR
63.7(f).
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\4\ The emission limits for the individual non-Hg HAP metals and
the total non-Hg HAP metals have been reduced by two-thirds,
consistent with the revision of the fPM emission limit from 0.030
lb/MMBtu to 0.010 lb/MMBtu.
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The EPA is also finalizing, as proposed, a more protective Hg
emission standard for existing lignite-fired EGUs, requiring that such
lignite-fired EGUs meet the same Hg emission standard as EGUs firing
other types of coal (i.e., bituminous and subbituminous), which is 1.2
lb of Hg per trillion British thermal units of heat input (lb/TBtu) or
an alternative output-based standard of 0.013 lb per gigawatt-hour (lb/
GWh). Finally, the EPA is finalizing, as proposed, the removal of the
second option for defining the startup period for MATS-affected EGUs.
The EPA did not propose and is not finalizing modifications to the
HCl emission standard (nor the alternative sulfur dioxide
(SO<INF>2</INF>) emission standard), which serves as a surrogate for
all acid gas HAP (HCl, hydrogen fluoride (HF), selenium dioxide
(SeO<INF>2</INF>)) for existing coal-fired EGUs. The EPA proposed to
require PM CEMS for existing integrated gasification combined cycle
(IGCC) EGUs but is not finalizing this requirement due to technical
issues calibrating CEMS on these types of EGUs and the related fact
that fPM emissions from IGCCs are very low.
In establishing the final standards, as discussed in detail in
sections IV., V., VI., and VII. of this preamble, the EPA considered
the statutory direction and factors laid out by Congress in CAA section
112. Separately, pursuant to Executive Order 12866 and Executive Order
14904, the EPA prepared an analysis of the potential costs and benefits
associated with this action. This analysis, Regulatory Impact Analysis
for the Final National Emission Standards for Hazardous Air Pollutants:
Coal- and Oil-Fired Electric Utility Steam Generating Units Review of
the Residual Risk and Technology Review (Ref. EPA-452/R-24-005), is
available in the docket, and is briefly summarized in sections I.A.3.
and IX. of this preamble.
3. Costs and Benefits
In accordance with Executive Order 12866 and 14094, the EPA
prepared a Regulatory Impact Analysis (RIA). The RIA presents estimates
of the emission, cost, and benefit impacts of this final rulemaking for
the 2028 to 2037 period; those estimates are summarized in this
section.
The power industry's compliance costs are represented in the RIA as
the projected change in electric power generation costs between the
baseline and final rule scenarios. The quantified emission estimates
presented in the RIA include changes in pollutants directly covered by
this rule, such as Hg and non-Hg HAP metals, and changes in other
pollutants emitted from the power sector due to the compliance actions
projected under this final rule. The cumulative projected national-
level emissions reductions over the 2028 to 2037 period under the
finalized requirements are presented in table 1. The supporting details
for these estimates can be found in the RIA.
BILLING CODE 6560-50-P
[[Page 38511]]
[GRAPHIC] [TIFF OMITTED] TR07MY24.065
The EPA expects that emission reductions under the final rulemaking
will result in reduced exposure to Hg and non-Hg HAP metals. The EPA
also projects health benefits due to improvements in particulate matter
with a diameter of 2.5 micrometers or less (PM<INF>2.5</INF>) and ozone
and climate benefits from reductions in carbon dioxide (CO<INF>2</INF>)
emissions. The EPA also anticipates benefits from the increased
transparency to the public, the assurance that standards are being met
continuously, and the accelerated identification of anomalous emissions
due to requiring PM CEMS in this final rule.
The EPA estimates negative net monetized benefits of this rule (see
table 2 below). However, the benefit estimates informing this result
represent only a partial accounting of the potential benefits of this
final rule. Several categories of human welfare and climate benefits
are unmonetized and are thus not directly reflected in the quantified
net benefit estimates (see section IX.B. in this preamble and section 4
of the RIA for more details). In particular, estimating the economic
benefits of reduced exposure to HAP generally has proven difficult for
a number of reasons: it is difficult to undertake epidemiologic studies
that have sufficient power to quantify the risks associated with HAP
exposures experienced by U.S. populations on a daily basis; data used
to estimate exposures in critical microenvironments are limited; and
there remains insufficient economic research to support valuation of
HAP benefits made even more challenging by the wide array of HAP and
possible HAP effects.\5\ In addition, due to data limitations, the EPA
is also unable to quantify potential emissions impacts or monetize
potential benefits from continuous monitoring requirements.
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\5\ See section II.B.2. for discussion of the public health and
environmental hazards associated with HAP emissions from coal- and
oil-fired EGUs and discussion on the limitations to monetizing and
quantifying benefits from HAP reductions. See also National Emission
Standards for Hazardous Air Pollutants: Coal- and Oil-Fired Electric
Utility Steam Generating Units--Revocation of the 2020
Reconsideration and Affirmation of the Appropriate and Necessary
Supplemental Finding, 88 FR 13956, 13970-73 (March 6, 2023).
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The present value (PV) and equivalent annual value (EAV) of costs,
benefits, and net benefits of this rulemaking over the 2028 to 2037
period in 2019 dollars are shown in table 2. In this table, results are
presented using a 2 percent discount rate. Results under other discount
rates and supporting details for the estimates can be found in the RIA.
[[Page 38512]]
[GRAPHIC] [TIFF OMITTED] TR07MY24.066
BILLING CODE 6560-50-C
The EPA notes that analysis of such impacts is distinct from the
determinations finalized in this action under CAA section 112, which
are based on the statutory factors the EPA discusses in section II.A.
and sections IV. through VII. below.
B. Does this action apply to me?
Regulated entities. The source category that is the subject of this
action is coal- and oil-fired EGUs regulated by NESHAP under 40 CFR
part 63, subpart UUUUU, commonly known as MATS. The North American
Industry Classification System (NAICS) codes for the coal- and oil-
fired EGU source category are 221112, 221122, and 921150. This list of
NAICS codes is not intended to be exhaustive, but rather to provide a
guide for readers regarding entities likely to be affected by the final
action for the source category listed. To determine whether your
facility is affected, you should examine the applicability criteria in
the appropriate NESHAP. If you have any questions regarding the
applicability of any aspect of this NESHAP, please contact the
appropriate person listed in the preceding FOR FURTHER INFORMATION
CONTACT section of this preamble.
C. Where can I get a copy of this document and other related
information?
In addition to being available in the docket, an electronic copy of
this final action will also be available on the internet. Following
signature by the EPA Administrator, the EPA will post a copy of this
final action at: <a href="https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards">https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards</a>. Following publication in the Federal
Register, the EPA will post the Federal Register version and key
technical documents at this same website.
Additional information is available on the RTR website at <a href="https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous">https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous</a>. This information
includes an overview of the RTR program and links to project websites
for the RTR source categories.
D. Judicial Review and Administrative Reconsideration
Under CAA section 307(b)(1), judicial review of this final action
is available only by filing a petition for review in the United States
Court of Appeals for the District of Columbia Circuit (the Court) by
July 8, 2024. Under CAA section 307(b)(2), the requirements established
by this final rule may not be challenged separately in any civil or
criminal proceedings brought by the EPA to enforce the requirements.
Section 307(d)(7)(B) of the CAA further provides that only an
objection to a rule or procedure that was raised with reasonable
specificity during the period for public comment (including any public
hearing) may be raised during judicial review. This section also
provides a mechanism for the EPA to reconsider the rule if the person
raising an objection can demonstrate to the Administrator that it was
impracticable to raise such objection within the period for public
comment or if the grounds for such objection arose after the period for
public comment (but within the time specified for judicial review) and
if such objection is of central relevance to the outcome of the rule.
Any person seeking to make such a demonstration should submit a
Petition for Reconsideration to the Office of the Administrator, U.S.
EPA, Room 3000, WJC South Building, 1200 Pennsylvania Ave., NW,
Washington, DC 20460, with a copy to both the person(s) listed in the
preceding FOR FURTHER INFORMATION CONTACT section, and the Associate
[[Page 38513]]
General Counsel for the Air and Radiation Law Office, Office of General
Counsel (Mail Code 2344A), U.S. EPA, 1200 Pennsylvania Ave. NW,
Washington, DC 20460.
II. Background
A. What is the statutory authority for this action?
1. Statutory Language
The statutory authority for this action is provided by sections 112
and 301 of the CAA, as amended (42 U.S.C. 7401 et seq.). Section 112 of
the CAA establishes a multi-stage regulatory process to develop
standards for emissions of HAP from stationary sources. Generally,
during the first stage, Congress directed the EPA to establish
technology-based standards to ensure that all major sources control HAP
emissions at the level achieved by the best-performing sources,
referred to as the MACT. After the first stage, Congress directed the
EPA to review those standards periodically to determine whether they
should be strengthened. Within 8 years after promulgation of the
standards, the EPA must evaluate the MACT standards to determine
whether the emission standards should be revised to address any
remaining risk associated with HAP emissions. This second stage is
commonly referred to as the ``residual risk review.'' In addition, the
CAA also requires the EPA to review standards set under CAA section 112
on an ongoing basis no less than every 8 years and revise the standards
as necessary taking into account any ``developments in practices,
processes, and control technologies.'' This review is commonly referred
to as the ``technology review,'' and is the primary subject of this
final rule. The discussion that follows identifies the most relevant
statutory sections and briefly explains the contours of the methodology
used to implement these statutory requirements.
In the first stage of the CAA section 112 standard-setting process,
the EPA promulgates technology-based standards under CAA section 112(d)
for categories of sources identified as emitting one or more of the HAP
listed in CAA section 112(b). Sources of HAP emissions are either major
sources or area sources, and CAA section 112 establishes different
requirements for major source standards and area source standards.
``Major sources'' are those that emit or have the potential to emit 10
tons per year (tpy) or more of a single HAP or 25 tpy or more of any
combination of HAP. All other sources are ``area sources.'' For major
sources, CAA section 112(d)(2) provides that the technology-based
NESHAP must reflect ``the maximum degree of reduction in emissions of
the [HAP] subject to this section (including a prohibition on such
emissions, where achievable) that the Administrator, taking into
consideration the cost of achieving such emission reduction, and any
nonair quality health and environmental impacts and energy
requirements, determines is achievable.'' (emphasis added). These
standards are commonly referred to as MACT standards. CAA section
112(d)(3) establishes a minimum control level for MACT standards, known
as the MACT ``floor.'' \6\ In certain instances, as provided in CAA
section 112(h), the EPA may set work practice standards in lieu of
numerical emission standards. The EPA must also consider control
options that are more stringent than the floor. Standards more
stringent than the floor are commonly referred to as ``beyond-the-
floor'' standards. For area sources, CAA section 112(d)(5) allows the
EPA to set standards based on generally available control technologies
or management practices (GACT standards) in lieu of MACT standards.\7\
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\6\ Specifically, for existing sources, the MACT ``floor'' shall
not be less stringent than the average emission reduction achieved
by the best performing 12 percent of existing sources. 42 U.S.C.
7412(d)(3). For new sources MACT shall not be less stringent than
the emission control that is achieved in practice by the best
controlled similar source. Id.
\7\ For categories of area sources subject to GACT standards,
there is no requirement to address residual risk, but, similar to
the major source categories, the technology review is required.
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For categories of major sources and any area source categories
subject to MACT standards, the next stage in standard-setting focuses
on identifying and addressing any remaining (i.e., ``residual'') risk
pursuant to CAA section 112(f)(2). The residual risk review requires
the EPA to update standards if needed to provide an ample margin of
safety to protect public health.
Concurrent with that review, and then at least every 8 years
thereafter, CAA section 112(d)(6) requires the EPA to review standards
promulgated under CAA section 112 and revise them ``as necessary
(taking into account developments in practices, processes, and control
technologies).'' See Portland Cement Ass'n v. EPA, 665 F.3d 177, 189
(D.C. Cir. 2011) (``Though EPA must review and revise standards `no
less often than every eight years,' 42 U.S.C. 7412(d)(6), nothing
prohibits EPA from reassessing its standards more often.''). In
conducting this review, which we call the ``technology review,'' the
EPA is not required to recalculate the MACT floors that were
established in earlier rulemakings. Natural Resources Defense Council
(NRDC) v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008); Association of
Battery Recyclers, Inc. v. EPA, 716 F.3d 667 (D.C. Cir. 2013). The EPA
may consider cost in deciding whether to revise the standards pursuant
to CAA section 112(d)(6). See e.g., Nat'l Ass'n for Surface Finishing,
v. EPA, 795 F.3d 1, 11 (D.C. Cir. 2015). The EPA is required to address
regulatory gaps, such as missing MACT standards for listed air toxics
known to be emitted from the source category. Louisiana Environmental
Action Network (LEAN) v. EPA, 955 F.3d 1088 (D.C. Cir. 2020). The
residual risk review and the technology review are distinct
requirements and are both mandatory.
In this action, the EPA is finalizing amendments to the MACT
standards based on two independent sources of authority: (1) its review
of the 2020 Final Action's risk and technology review pursuant to the
EPA's statutory authority under CAA section 112, and (2) the EPA's
inherent authority to reconsider previous decisions and to revise,
replace, or repeal a decision to the extent permitted by law and
supported by a reasoned explanation. FCC v. Fox Television Stations,
Inc., 556 U.S. 502, 515 (2009); see also Motor Vehicle Mfrs. Ass'n v.
State Farm Mutual Auto. Ins. Co., 463 U.S. 29, 42 (1983).
2. Statutory Structure and Legislative History
In addition to the text of the specific subsections of CAA section
112 discussed above, the statutory structure and legislative history of
CAA section 112 further support the EPA's authority to take this
action. Throughout CAA section 112 and its legislative history,
Congress made clear its intent to quickly secure large reductions in
the volume of HAP emissions from stationary sources based on
technological developments in control technologies because of its
recognition of the hazards to public health and the environment that
result from exposure to such emissions. CAA section 112 and its
legislative history also reveal Congress's understanding that fully
characterizing the risks posed by HAP emissions was exceedingly
difficult. Thus, Congress purposefully replaced a regime that required
the EPA to make an assessment of risk in the first instance, with one
in which Congress determined risk existed and directed the EPA to make
swift and substantial reductions based upon the most stringent
standards technology could achieve.
Specifically, in 1990, Congress radically transformed section 112
of the CAA and its treatment of HAP through the Clean Air Act
Amendments, by
[[Page 38514]]
amending CAA section 112 to be a technology-driven standard setting
provision as opposed to the risk-based one that Congress initially
promulgated in the 1970 CAA. The legislative history of the 1990
Amendments indicates Congress's dissatisfaction with the EPA's slow
pace addressing HAP under the 1970 CAA: ``In theory, [hazardous air
pollutants] were to be stringently controlled under the existing Clean
Air Act section 112. However, . . . only 7 of the hundreds of
potentially hazardous air pollutants have been regulated by EPA since
section 112 was enacted in 1970.'' H.R. Rep. No. 101-490, at 315
(1990); see also id. at 151 (noting that in 20 years, the EPA's
establishment of standards for only seven HAP covered ``a small
fraction of the many substances associated . . . with cancer, birth
defects, neurological damage, or other serious health impacts.'').
In enacting the 1990 Amendments with respect to the control of HAP,
Congress noted that ``[p]ollutants controlled under [section 112] tend
to be less widespread than those regulated [under other sections of the
CAA], but are often associated with more serious health impacts, such
as cancer, neurological disorders, and reproductive dysfunctions.'' Id.
at 315. In its substantial 1990 Amendments, Congress itself listed 189
HAP (CAA section 112(b)) and set forth a statutory structure that would
ensure swift regulation of a significant majority of these HAP
emissions from stationary sources. Specifically, after defining major
and area sources and requiring the EPA to list all major sources and
many area sources of the listed pollutants (CAA section 112(c)), the
new CAA section 112 required the EPA to establish technology-based
emission standards for listed source categories on a prompt schedule
and to revisit those technology-based standards every 8 years on an
ongoing basis (CAA section 112(d) (emission standards); CAA section
112(e) (schedule for standards and review)). The 1990 Amendments also
obligated the EPA to conduct a one-time evaluation of the residual risk
within 8 years of promulgation of technology-based standards. CAA
section 112(f)(2).
In setting the standards, CAA section 112(d) requires the EPA to
establish technology-based standards that achieve the ``maximum degree
of reduction,'' ``including a prohibition on such emissions where
achievable.'' CAA section 112(d)(2). Congress specified that the
maximum degree of reduction must be at least as stringent as the
average level of control achieved in practice by the best performing
sources in the category or subcategory based on emissions data
available to the EPA at the time of promulgation. This technology-based
approach enabled the EPA to swiftly set standards for source categories
without determining the risk or cost in each specific case, as the EPA
had done prior to the 1990 Amendments. In other words, this approach to
regulation quickly required that all major sources and many area
sources of HAP meet an emission standard consistent with the top
performers in each category, which had the effect of obtaining
immediate reductions in the volume of HAP emissions from stationary
sources. The statutory requirement that sources obtain levels of
emission limitation that have actually been achieved by existing
sources, instead of levels that could theoretically be achieved,
inherently reflects a built-in cost consideration.\8\
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\8\ Congress recognized as much: ``The Administrator may take
the cost of achieving the maximum emission reduction and any non-air
quality health and environmental impacts and energy requirements
into account when determining the emissions limitation which is
achievable for the sources in the category or subcategory. Cost
considerations are reflected in the selection of emissions
limitations which have been achieved in practice (rather than those
which are merely theoretical) by sources of a similar type or
character.'' A Legislative History of the Clean Air Act Amendments
of 1990 (CAA Legislative History), Vol 5, pp. 8508-8509 (CAA
Amendments of 1989; p. 168-169; Report of the Committee on
Environment and Public Works S. 1630).
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Further, after determining the minimum stringency level of control,
or MACT floor, CAA section 112(d)(2) directs the EPA to ``require the
maximum degree of reduction in emissions of the hazardous air
pollutants subject to this section (including a prohibition on such
emissions, where achievable)'' that the EPA determines are achievable
after considering the cost of achieving such standards and any non-air-
quality health and environmental impacts and energy requirements of
additional control. In doing so, the statute further specifies in CAA
section 112(d)(2) that the EPA should consider requiring sources to
apply measures that, among other things, ``reduce the volume of, or
eliminate emissions of, such pollutants . . . '' (CAA section
112(d)(2)(A)), ``enclose systems or processes to eliminate emissions''
(CAA section 112(d)(2)(B)), and ``collect, capture, or treat such
pollutants when released . . . '' (CAA section 112(d)(2)(C)). The 1990
Amendments also built in a regular review of new technologies and a
one-time review of risks that remain after imposition of MACT
standards. CAA section 112(d)(6) requires the EPA to evaluate every
NESHAP no less often than every 8 years to determine whether additional
control is necessary after taking into consideration ``developments in
practices, processes, and control technologies,'' separate from its
obligation to review residual risk. CAA section 112(f) requires the EPA
to ensure within 8 years of promulgating a NESHAP that the risks are
acceptable and that the MACT standards provide an ample margin of
safety.
The statutory requirement to establish technology-based standards
under CAA section 112 eliminated the requirement for the EPA to
identify hazards to public health and the environment in order to
justify regulation of HAP emissions from stationary sources, reflecting
Congress's judgment that such emissions are inherently dangerous. See
S. Rep. No. 101-228, at 148 (``The MACT standards are based on the
performance of technology, and not on the health and environmental
effects of the [HAP].''). The technology review required in CAA section
112(d)(6) further mandates that the EPA continually reassess standards
to determine if additional reductions can be obtained, without
evaluating the specific risk associated with the HAP emissions that
would be reduced. Notably, Congress required the EPA to conduct the CAA
section 112(d)(6) review of what additional reductions may be obtained
based on new technology even after the EPA has conducted the one-time
CAA section 112(f)(2) risk review and determined that the existing
standard will protect the public with an ample margin of safety. The
two requirements are distinct, and both are mandatory.
B. What is the Coal- and Oil-Fired EGU source category and how does the
NESHAP regulate HAP emissions from the source category?
1. Summary of Coal- and Oil-Fired EGU Source Category and NESHAP
Regulations
The EPA promulgated the Coal- and Oil-Fired EGU NESHAP (commonly
referred to as MATS) on February 16, 2012 (77 FR 9304) (2012 MATS Final
Rule). The standards are codified at 40 CFR part 63, subpart UUUUU. The
coal- and oil-fired electric utility industry consists of facilities
that burn coal or oil located at both major and area sources of HAP
emissions. An existing affected source is the collection of coal- or
oil-fired EGUs in a subcategory within a single contiguous area and
under common control. A new affected source is each coal- or oil-fired
EGU for which construction or reconstruction began
[[Page 38515]]
after May 3, 2011. An EGU is a fossil fuel-fired combustion unit of
more than 25 megawatts (MW) that serves a generator that produces
electricity for sale. A unit that cogenerates steam and electricity and
supplies more than one-third of its potential electric output capacity
and more than 25 MW electric output to any utility power distribution
system for sale is also considered an EGU. The 2012 MATS Final Rule
defines additional terms for determining rule applicability, including,
but not limited to, definitions for ``coal-fired electric utility steam
generating unit,'' ``oil-fired electric utility steam generating
unit,'' and ``fossil fuel-fired.'' In 2028, the EPA expects the source
category covered by this MACT standard to include 314 coal-fired steam
generating units (140 GW at 157 facilities), 58 oil-fired steam
generating units (23 GW at 35 facilities), and 5 IGCC units (0.8 GW at
2 facilities).
For coal-fired EGUs, the 2012 MATS Final Rule established standards
to limit emissions of Hg, acid gas HAP (e.g., HCl, HF), non-Hg HAP
metals (e.g., nickel, lead, chromium), and organic HAP (e.g.,
formaldehyde, dioxin/furan). Emission standards for HCl serve as a
surrogate for the acid gas HAP, with an alternate standard for
SO<INF>2</INF> that may be used as a surrogate for acid gas HAP for
those coal-fired EGUs with flue gas desulfurization (FGD) systems and
SO<INF>2</INF> CEMS installed and operational. Standards for fPM serve
as a surrogate for the non-Hg HAP metals. Work practice standards limit
formation and emissions of organic HAP.
For oil-fired EGUs, the 2012 MATS Final Rule established standards
to limit emissions of HCl and HF, total HAP metals (e.g., Hg, nickel,
lead), and organic HAP (e.g., formaldehyde, dioxin/furan). Standards
for fPM also serve as a surrogate for total HAP metals, with standards
for total and individual HAP metals provided as alternative equivalent
standards. Work practice standards limit formation and emissions of
organic HAP.
MATS includes standards for existing and new EGUs for eight
subcategories: three for coal-fired EGUs, one for IGCC EGUs, one for
solid oil-derived fuel-fired EGUs (i.e., petroleum coke-fired), and
three for liquid oil-fired EGUs. EGUs in seven of the subcategories are
subject to numeric emission limits for all the pollutants described
above except for organic HAP (limited-use liquid oil-fired EGUs are not
subject to numeric emission limits). Emissions of organic HAP are
regulated by a work practice standard that requires periodic combustion
process tune-ups. EGUs in the subcategory of limited-use liquid oil-
fired EGUs with an annual capacity factor of less than 8 percent of its
maximum or nameplate heat input are also subject to a work practice
standard consisting of periodic combustion process tune-ups but are not
subject to any numeric emission limits. Emission limits for existing
EGUs and additional information of the history and other requirements
of the 2012 MATS Final Rule are available in the 2023 Proposal preamble
(88 FR 24854).
2. Public Health and Environmental Hazards Associated With Emissions
From Coal- and Oil-Fired EGUs
Coal- and oil-fired EGUs are a significant source of numerous HAP
that are associated with adverse effects to human health and the
environment, including Hg, HF, HCl, selenium, arsenic, chromium,
cobalt, nickel, hydrogen cyanide, beryllium, and cadmium emissions. Hg
is a persistent and bioaccumulative toxic metal that, once released
from power plants into the ambient air, can be readily transported and
deposited to soil and aquatic environments where it is transformed by
microbial action into methylmercury.\9\ Methylmercury bioaccumulates in
the aquatic food web eventually resulting in highly concentrated levels
of methylmercury within the larger and longer-living fish (e.g., carp,
catfish, trout, and perch), which can then be consumed by humans.
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\9\ U.S. EPA. 1997, Mercury Study Report to Congress, EPA-452/R-
97-003 (December 1997); see also 76 FR 24976 (May 3, 2011); 80 FR
75029 (December 1, 2015).
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Of particular concern is chronic prenatal exposure via maternal
consumption of foods containing methylmercury. Elevated exposure has
been associated with developmental neurotoxicity and manifests as poor
performance on neurobehavioral tests, particularly on tests of
attention, fine motor function, language, verbal memory, and visual-
spatial ability. Evidence also suggests potential for adverse effects
on the cardiovascular system, adult nervous system, and immune system,
as well as potential for causing cancer. Because the impacts of the
neurodevelopmental effects of methylmercury are greatest during periods
of rapid brain development, developing fetuses, infants, and young
children are particularly vulnerable. Children born to populations with
high fish consumption (e.g., people consuming fish as a dietary staple)
or impaired nutritional status may be especially susceptible to adverse
neurodevelopmental outcomes. These dietary and nutritional risk factors
are often particularly pronounced in vulnerable communities with people
of color and low-income populations that have historically faced
economic and environmental injustice and are overburdened by cumulative
levels of pollution. In addition to adverse neurodevelopmental effects,
there is evidence that exposure to methylmercury in humans and animals
can have adverse effects on both the developing and adult
cardiovascular system.
Along with the human health hazards associated with methylmercury,
it is well-established that birds and mammals are also exposed to
methylmercury through fish consumption (Mercury Study). At higher
levels of exposure, the harmful effects of methylmercury include slower
growth and development, reduced reproduction, and premature mortality.
The effects of methylmercury on wildlife are variable across species
but have been observed in the environment for numerous avian species
and mammals including polar bears, river otters, and panthers.
EGUs are also the largest source of HCl, HF, and selenium
emissions, and are a major source of metallic HAP emissions including
arsenic, chromium, nickel, cobalt, and others. Exposure to these HAP,
depending on exposure duration and levels of exposures, is associated
with a variety of adverse health effects. These adverse health effects
may include chronic health disorders (e.g., pneumonitis, decreased
pulmonary function, pneumonia, or lung damage; detrimental effects on
the central nervous system; damage to the kidneys) and alimentary
effects (such as nausea and vomiting). As of 2021, three of the key
metal HAP emitted by EGUs (arsenic, chromium, and nickel) have been
classified as human carcinogens, while three others (cadmium, selenium,
and lead) are classified as probable human carcinogens. Overall (metal
and nonmetal), the EPA has classified four of the HAP emitted by EGUs
as human carcinogens and five as probable human carcinogens.
While exposure to HAP is associated with a variety of adverse
effects, quantifying the economic value of these impacts remains
challenging. Epidemiologic studies, which report a central estimate of
population-level risk, are generally used in an air pollution benefits
assessment to estimate the number of attributable cases of events.
Exposure to HAP is typically more uneven and more highly concentrated
among a smaller number of individuals than exposure to criteria
pollutants.
[[Page 38516]]
Hence, conducting an epidemiologic study for HAP is inherently more
challenging; for starters, the small population size means such studies
often lack sufficient statistical power to detect effects (particularly
outcomes like cancer, for which there can exist a multi-year time lag
between exposure and the onset of the disease). By contrast, sufficient
power generally exists to detect effects for criteria pollutants
because exposures are ubiquitous and a variety of methods exist to
characterize this exposure over space and time.
For the reasons noted above, epidemiologic studies do not generally
exist for HAP. Instead, the EPA tends to rely on experimental animal
studies to identify the range of effects which may be associated with a
particular HAP exposure. Human controlled clinical studies are often
limited due to ethical barriers (e.g., knowingly exposing someone to a
carcinogen). Generally, robust data are needed to quantify the
magnitude of expected adverse impacts from varying exposures to a HAP.
These data are necessary to provide a foundation for quantitative
benefits analyses but are often lacking for HAP, made even more
challenging by the wide array of HAP and possible noncancer HAP
effects.
Finally, estimating the economic value of HAP is made challenging
by the human health endpoints affected. For example, though EPA can
quantify the number and economic value of HAP-attributable deaths
resulting from cancer, it is difficult to monetize the value of
reducing an individual's potential cancer risk attributable to a
lifetime of HAP exposure. An alternative approach of conducting
willingness to pay studies specifically on risk reduction may be
possible, but such studies have not yet been pursued.
C. Summary of the 2020 Residual Risk Review
As required by CAA section 112(f)(2), the EPA conducted the
residual risk review (2020 Residual Risk Review) in 2020, 8 years after
promulgating the 2012 MATS Final Rule, and presented the results of the
review, along with our decisions regarding risk acceptability, ample
margin of safety, and adverse environmental effects, in the 2020 Final
Action. The results of the risk assessment are presented briefly in
table 3 of this document, and in more detail in the document titled
Residual Risk Assessment for the Coal- and Oil-Fired EGU Source
Category in Support of the 2020 Risk and Technology Review Final Rule
(risk document for the final rule), available in the docket (Document
ID No. EPA-HQ-OAR-2018-0794-4553). The EPA summarized the results and
findings of the 2020 Residual Risk Review in the preamble of the 2023
Proposal (88 FR 24854), and additional information concerning the
residual risk review can be found in our National-Scale Mercury Risk
Estimates for Cardiovascular and Neurodevelopmental Outcomes for the
National Emission Standards for Hazardous Air Pollutants: Coal- and
Oil-Fired Electric Utility Steam Generating Units--Revocation of the
2020 Reconsideration, and Affirmation of the Appropriate and Necessary
Finding; Notice of Proposed Rulemaking memorandum (Document ID No. EPA-
HQ-OAR-2018-0794-4605).
BILLING CODE 6560-50-P
[[Page 38517]]
[GRAPHIC] [TIFF OMITTED] TR07MY24.067
BILLING CODE 6560-50-C
D. Summary of the 2020 Technology Review
Pursuant to CAA section 112(d)(6), the EPA conducted a technology
review (2020 Technology Review) in the 2020 Final Action, which focused
on identifying and evaluating developments in practices, processes, and
control technologies for the emission sources in the source category
that occurred since the 2012 MATS Final Rule was promulgated. Control
technologies typically used to minimize emissions of pollutants that
have numeric emission limits under the 2012 MATS Final Rule include
electrostatic precipitators (ESPs) and fabric filters (FFs) for control
of fPM as a surrogate for non-Hg HAP metals; wet scrubbers, dry
scrubbers, and dry sorbent injection for control of acid gases
(SO<INF>2</INF>, HCl, and HF); and activated carbon injection (ACI) and
other Hg-specific technologies for control of Hg. The EPA determined
that the existing air pollution control technologies that were in use
were well-established and provided the capture efficiencies necessary
for compliance with the MATS emission limits. Based on the
effectiveness and proven reliability of these control technologies, and
the relatively short period of time since the promulgation of the 2012
MATS Final Rule, the EPA did not identify any developments in
practices, processes, or control technologies, nor any new technologies
or practices, for the control of non-Hg HAP metals, acid gas HAP, or
Hg. However, in the 2020 Technology Review, the EPA did not consider
developments in the cost and effectiveness of these proven
technologies, nor did the EPA evaluate the current performance of
emission reduction control equipment and strategies at existing MATS-
affected EGUs, to determine whether revising the standards was
warranted. Organic HAP, including emissions of dioxins and furans, are
regulated by a work practice standard that requires periodic burner
tune-ups to ensure good combustion. The EPA found that this work
practice continued to be a practical approach to ensuring that
combustion equipment was maintained and optimized to run to reduce
emissions of organic HAP and continued to be more effective than
establishing a numeric standard that cannot reliably be measured or
monitored. Based on the effectiveness and proven reliability of the
work practice standard, and the relatively short amount of time since
the promulgation of the 2012 MATS Final Rule, the EPA did not identify
any developments in work practices nor any new work practices or
operational procedures for this source category regarding the
additional control of organic HAP.
After conducting the 2020 Technology Review, the EPA did not
identify developments in practices, processes, or
[[Page 38518]]
control technologies and, thus, did not propose changes to any emission
standards or other requirements. More information concerning that
technology review is in the memorandum titled Technology Review for the
Coal- and Oil-Fired EGU Source Category, available in the docket
(Document ID No. EPA-HQ-OAR-2018-0794-0015), and in the February 7,
2019, proposed rule. 84 FR 2700. On May 20, 2020, the EPA finalized the
first technology review required by CAA section 112(d)(6) for the coal-
and oil-fired EGU source category regulated under MATS. Based on the
results of that technology review, the EPA found that no revisions to
MATS were warranted. See 85 FR 31314 (May 22, 2020).
E. Summary of the EPA's Review of the 2020 RTR and the 2023 Proposed
Revisions to the NESHAP
Pursuant to CAA section 112(d)(6), the EPA conducted a review of
the 2020 Technology Review and presented the results of this review,
along with our proposed decisions, in the 2023 Proposal. The results of
the technology review are presented briefly below in this preamble.
More detail on the proposed technology review is in the memorandum 2023
Technology Review for the Coal- and Oil-Fired EGU Source Category
(``2023 Technical Memo'') (Document ID No. EPA-HQ-OAR-2018-0794-5789).
Based on the results of the technology review, the EPA proposed to
lower the fPM standard, the surrogate for non-Hg HAP metals, for coal-
fired EGUs from 0.030 lb/MMBtu to 0.010 lb/MMBtu. The Agency solicited
comment on the control technology effectiveness and cost assumptions
used in the proposed rule, as well as on a more stringent fPM limit of
0.006 lb/MMBtu or lower. Additionally, the Agency proposed to require
the use of PM CEMS for all coal-fired, oil-fired, and IGCC EGUs for
demonstrating compliance with the fPM standard. As the Agency proposed
to require PM CEMS for compliance demonstration, we also proposed to
remove the LEE option, a program based on infrequent stack testing, for
fPM and non-Hg HAP metals. As EGUs would be required to demonstrate
compliance with PM CEMS, the Agency also proposed to remove the
alternate emission standards for non-Hg HAP metals and total HAP
metals, because almost all regulated sources have chosen to demonstrate
compliance with the non-Hg HAP metal standards by demonstrating
compliance with the surrogate fPM standard, and solicited comment on
prorated metal limits (adjusted proportionally according to the level
of the final fPM standard), should the Agency not finalize the removal
of the non-Hg HAP metals limits.
The Agency also proposed to lower the Hg emission standard for
lignite-fired EGUs from 4.0 lb/TBtu to 1.2 lb/TBtu and solicited
comment on the performance of Hg controls and on cost and effectiveness
of control strategies to meet more stringent Hg standards. Lastly, the
EPA did not identify new developments in control technologies or
improved methods of operation that would warrant revisions to the Hg
emission standards for non-lignite EGUs, for the organic HAP work
practice standards, for the acid gas standards, or for standards for
oil-fired EGUs. Therefore, the Agency did not propose changes to these
standards in the 2023 Proposal but did solicit comment on the EPA's
proposed findings that no revisions were warranted and on the
appropriateness of the existing standards.
Additionally, the EPA proposed to remove one of the two options for
defining the startup period for MATS-affected EGUs.
In the 2023 Proposal, the EPA determined not to reopen the 2020
Residual Risk Review, and accordingly did not propose any revisions to
that review. As the EPA explained in the proposal, the EPA found in the
2020 RTR that risks from the Coal- and Oil-Fired EGU source category
due to emissions of air toxics are acceptable and that the existing
NESHAP provides an ample margin of safety to protect public health. As
noted in the proposal, the EPA also acknowledges that it received a
petition for reconsideration from environmental organizations that, in
relevant part, sought the EPA's reconsideration of certain aspects of
the 2020 Residual Risk Review. The EPA granted in part the
environmental organizations' petition which sought the EPA's review of
startup and shutdown provisions in the 2023 Proposal, 88 FR 24885, and
the EPA continues to review and will respond to other aspects of the
petition in a separate action.\10\
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\10\ See Document ID No. EPA-HQ-OAR-2018-0794-4565 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
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III. What is included in this final rule?
This action finalizes the EPA's determinations pursuant to the RTR
provisions of CAA section 112 for the Coal- and Oil-Fired EGU source
category and amends the Coal- and Oil-Fired EGU NESHAP based on those
determinations. This action also finalizes changes to the definition of
startup for this rule. This final rule includes changes to the 2023
Proposal after consideration of comments received during the public
comment period described in sections IV., V., VI., and VII. of this
preamble.
A. What are the final rule amendments based on the technology review
for the Coal- and Oil-Fired EGU source category?
We determined that there are developments in practices, processes,
and control technologies that warrant revisions to the MACT standards
for this source category. Therefore, to satisfy the requirements of CAA
section 112(d)(6), we are revising the MACT standards by revising the
fPM limit for existing coal-fired EGUs from 0.030 lb/MMBtu to 0.010 lb/
MMBtu and requiring the use of PM CEMS for coal and oil-fired EGUs to
demonstrate compliance with the revised fPM standard, as proposed. We
are also finalizing, as proposed, a Hg limit for lignite-fired EGUs of
1.2 lb/TBtu, which aligns with the existing Hg limit that has been in
effect for other coal-fired EGUs since 2012. This revised Hg limit for
lignite-fired EGUs is more stringent than the limit of 4.0 lb/TBtu that
was finalized for such units in the 2012 MATS Final Rule. The rationale
for these changes is discussed in more detail in sections IV. and V.
below.
Based on comments received during the public comment period, the
EPA is not finalizing the proposed removal of the non-Hg HAP metals
limits for existing coal-fired EGUs (see section V.). Additionally,
this final rule is requiring the use of PM CEMS for compliance
demonstration for coal- and oil-fired EGUs (excluding EGUs in the
limited-use liquid oil-fired subcategory), but not for IGCC EGUs (see
section VI.).
Because this final rule includes revisions to the emissions
standards for fPM as a surrogate for non-Hg HAP metals for existing
coal-fired EGUs, the fPM emission standard compliance demonstration
requirements, the Hg emission standard for lignite-fired EGUs, and the
definition of ``startup,'' the EPA intends each portion of this rule to
be severable from each other as it is multifaceted and addresses
several distinct aspects of MATS for independent reasons. This includes
the revised emission standard for fPM as a surrogate for non-Hg HAP
metals and the fPM compliance demonstration requirement to utilize PM
CEMS. While the EPA considered the technical feasibility of PM CEMS in
establishing the revised fPM standard, the EPA finds there are
independent reasons for adopting each revision to the standards, and
that each would continue to be workable without the other in the place.
[[Page 38519]]
The EPA intends that the various pieces of this package be
considered independent of each other. For example, the EPA notes that
our judgments regarding developments in fPM control technology for the
revised fPM standard as a surrogate for non-Hg HAP metals largely
reflect that the fleet was reporting fPM emission rates well below the
current standard and with lower costs than estimated during
promulgation of the 2012 MATS Final Rule; while our judgments regarding
the ability for lignite-fired EGUs to meet the same standard for Hg
emissions as other coal- and oil-fired EGUs rest on a separate analysis
specific to lignite-fired units. Thus, the revised fPM surrogate
emissions standard is feasible and appropriate even absent the revised
Hg standard for lignite-fired units, and vice versa. Similarly, the EPA
is finalizing changes to the fPM compliance demonstration requirement
based on the technology's ability to provide increased transparency for
owners and operators, regulators, and the public; and the EPA is
finalizing changes to the startup definition based on considerations
raised by environmental groups in petitions for reconsideration. Both
of these actions are independent from the EPA's revisions to the fPM
surrogate standard, and the Hg standard for lignite-fired units.
Accordingly, the EPA finds that each set of standards is severable from
each other set of standards.
Finally, the EPA finds that implementation of each set of
standards, compliance demonstration requirements, and revisions to the
startup definition are independent. That is, a source can abide by any
one of these individual requirements without abiding by any others.
Thus, the EPA's overall approach to this source category continues to
be fully implementable even in the absence of any one or more of the
elements included in this final rule.
Thus, the EPA has independently considered and adopted each portion
of this final rule (including the revised fPM emission standard as a
surrogate for non-Hg HAP metals, the fPM compliance demonstration
requirement, the revised Hg emission standard for lignite-fired units,
and the revised startup definition) and each is severable should there
be judicial review. If a court were to invalidate any one of these
elements of the final rule, the EPA intends the remainder of this
action to remain effective. Importantly, the EPA designed the different
elements of this final rule to function sensibly and independently.
Further, the supporting bases for each element of the final rule
reflect the Agency's judgment that the element is independently
justified and appropriate, and that each element can function
independently even if one or more other parts of the rule has been set
aside.
B. What other changes have been made to the NESHAP?
The EPA is finalizing, as proposed, the removal of the work
practice standards of paragraph (2) of the definition of ``startup'' in
40 CFR 63.10042. Under the first option, startup ends when any of the
steam from the boiler is used to generate electricity for sale over the
grid or for any other purpose (including on-site use). Under the second
option, startup ends 4 hours after the EGU generates electricity that
is sold or used for any other purpose (including on-site use), or 4
hours after the EGU makes useful thermal energy (such as heat or steam)
for industrial, commercial, heating, or cooling purposes, whichever is
earlier. The final rule requires that all EGUs use the work practice
standards in paragraph (1) of the definition of ``startup,'' which is
already being used by the majority of EGUs.
C. What are the effective and compliance dates of the standards?
The revisions to the MACT standards being promulgated in this
action are effective on July 8, 2024. The compliance date for affected
coal-fired sources to comply with the revised fPM limit of 0.010 lb/
MMBtu and for lignite-fired sources to meet the lower Hg limit of 1.2
lb/TBtu is 3 years after the effective date of the final rule. The
Agency believes this timeline is as expeditious as practicable
considering the potential need for some sources to upgrade or replace
pollution controls. As discussed elsewhere in this preamble, we are
adding a requirement that compliance with the fPM limit be demonstrated
using PM CEMS. Based on comments received during the comment period and
our understanding of suppliers of PM CEMS, the EPA is finalizing the
requirement that affected sources use PM CEMS for compliance
demonstration by 3 years after the effective date of the final rule.
The compliance date for existing affected sources to comply with
amendments pertaining to the startup definition is 180 days after the
effective date of the final rule, as few EGUs are affected, and changes
needed to comply with paragraph (1) of startup are achievable by all
EGUs at little to no additional expenditures. All affected facilities
remain subject to the current requirements of 40 CFR part 63, subpart
UUUUU, until the applicable compliance date of the amended rule.
The EPA has considered the concerns raised by commenters that these
compliance deadlines could affect electric reliability and concluded
that given the flexibilities detailed further in this section, the
requirements of the final rule for existing sources can be met without
adversely impacting electric reliability. In particular, the EPA notes
the flexibility of permitting authorities to allow, if warranted, a
fourth year for compliance under CAA section 112(i)(3)(B). This
flexibility, if needed, would address many of the concerns that
commenters raised. Furthermore, in the event that an isolated,
localized concern were to emerge that could not be addressed solely
through the 1-year extension under CAA section 112(i)(3), the CAA
provides additional flexibilities to bring sources into compliance
while maintaining reliability.
The EPA notes that similar concerns regarding reliability were
raised about the 2012 MATS Final Rule--a rule that projected the need
for significantly greater installation of controls and other capital
investments than this current revision. In the 2012 MATS Final Rule,
the EPA emphasized that most units should be able to comply with the
requirements of the final rule within 3 years. However, the EPA also
made it clear that permitting authorities have the authority to grant a
1-year compliance extension where necessary, in a range of situations
described in the 2012 MATS Final Rule preamble.\11\ The EPA's Office of
Enforcement and Compliance Assurance (OECA) also issued the MATS
Enforcement Response policy (Dec. 16, 2011) \12\ which described the
approach regarding the issue of CAA section 113(a) administrative
orders with respect to the sources that must operate in noncompliance
with the MATS rule for up to 1 year to address specific documented
reliability concerns. While several affected EGUs requested and were
granted a 1-year CAA section 112(i)(3)(B) compliance extension by their
permitting authority, OECA only issued five administrative orders in
connection with the Enforcement Response policy. The 2012 MATS Final
Rule was ultimately implemented over the 2015--2016 timeframe without
challenges to grid reliability.
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\11\ 77 FR 9406.
\12\ <a href="https://www.epa.gov/enforcement/enforcement-response-policy-mercury-and-air-toxics-standard-mats">https://www.epa.gov/enforcement/enforcement-response-policy-mercury-and-air-toxics-standard-mats</a>.
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[[Page 38520]]
IV. What is the rationale for our final decisions and amendments to the
filterable PM (as a surrogate for non-Hg HAP metals) standard and
compliance options from the 2020 Technology Review?
In this section, the EPA provides descriptions of what we proposed,
what we are finalizing, our rationale for the final decisions and
amendments, and a summary of key comments and responses related to the
emission standard for fPM, non-Hg HAP metals, and the compliance
demonstration options. For all comments not discussed in this preamble,
comment summaries and the EPA's responses can be found in the comment
summary and response document National Emission Standards for Hazardous
Air Pollutants: Coal- and Oil-Fired Electric Utility Steam Generating
Units Review of the Residual Risk and Technology Review Proposed Rule
Response to Comments, available in the docket.
Based on its review, the EPA is finalizing a revised non-Hg HAP
metal surrogate fPM emission standard for all existing coal-fired EGUs
of 0.010 lb/MMBtu and is requiring that all coal- and oil-fired EGUs
demonstrate compliance with the revised fPM emission standard by using
PM CEMS. The revised fPM standard will ensure that the entire fleet of
coal-fired EGUs achieves performance levels that are consistent with
those of the vast majority of regulated units operating today--i.e.,
that the small minority of units that currently emit significantly
higher levels of HAP than their peers use proven technologies to reduce
their HAP to the levels achieved by the rest of the fleet. Further, the
EPA finds that a 0.010 lb/MMBtu fPM emission standard is the lowest
level currently compatible with PM CEMS for demonstrating compliance,
which the EPA finds provides significant benefits including increased
transparency regarding emissions performance for sources, regulators,
and the surrounding communities; and real-time identification of when
control technologies are not performing as expected, allowing for
quicker repairs. In addition, the rule's current requirement to shift
electronic reporting of PM CEMS data to the Emissions Collection and
Monitoring Plan System (ECMPS) will enable regulatory authorities,
nearby citizens, and others, including members of the public and media,
to quickly and easily locate, review, and download fPM emissions using
simple, user-directed inquiries. An enhanced, web-based version of
ECMPS (ECMPS 2.0) is currently being prepared that will ease data
editing, importing, and exporting and is expected to be available prior
to the date by which EGUs are required to use PM CEMS.
A. What did we propose pursuant to CAA section 112(d)(6) for the Coal-
and Oil-Fired EGU source category?
1. Proposed Changes to the Filterable PM Standard
The EPA proposed to lower the fPM limit, a surrogate for total non-
Hg HAP metals, for coal-fired EGUs from 0.030 lb/MMBtu to 0.010 lb/
MMBtu. The EPA further solicited comment on an emission standard of
0.006 lb/MMBtu or lower. The EPA did not propose any changes to the fPM
emission standard for oil-fired EGUs or for IGCC units. The EPA also
proposed to remove the total and individual non-Hg HAP metals emission
limits. The EPA also solicited comment on adjusting the total and
individual non-Hg HAP metals emission limits proportionally to the
revised fPM limit rather than eliminating the limits altogether.
2. Proposed Changes to the Requirements for Compliance Demonstration
The EPA proposed to require that all coal- and oil-fired EGUs (IGCC
units are discussed in section VI.) use PM CEMS to demonstrate
compliance with the fPM emission limit. The EPA also proposed to remove
the option of demonstrating compliance using infrequent stack testing
and the LEE program (where stack testing occurs quarterly for 3 years,
then every third year thereafter) for both PM and non-Hg HAP metals.
B. How did the technology review change for the Coal- and Oil-Fired EGU
source category?
1. Filterable PM Emission Standard
Commenters provided both supportive and opposing arguments for
issues regarding the fPM limit that were presented in the proposed
review of the 2020 Technology Review. Comments received on the proposed
fPM limit for coal-fired EGUs, along with additional analyses, did not
change the Agency's conclusions that were presented in the 2023
Proposal, and, therefore, the Agency is finalizing the 0.010 lb/MMBtu
fPM emission limit for existing coal-fired EGUs, as proposed.
Additionally, commenters urged the Agency to retain the option of
complying with individual non-Hg HAP metal (e.g., lead, arsenic,
chromium, nickel, and cadmium) emission rates or with a total non-Hg
HAP metal emission rate. After consideration of public comments, the
Agency is finalizing updated limits for non-Hg HAP metals and total
non-Hg HAP metals that have been reduced proportional to the reduction
of the fPM emission limit from 0.030 lb/MMBtu to the new final fPM
emission limit of 0.010 lb/MMBtu. EGU owners or operators who would
choose to comply with the non-Hg HAP metals emission limits instead of
the fPM limit must request and receive approval of a non-Hg HAP metal
CMS as an alternative test method (e.g., multi-metal CMS) under the
provisions of 40 CFR 63.7(f).
2. Compliance Demonstration Options
Comments received on the compliance demonstration options for coal-
and oil-fired EGUs also did not change the results of the technology
review, therefore the Agency is finalizing the use of PM CEMS for
compliance demonstration purposes and removing the fPM and non-Hg HAP
metals LEE options for all coal-fired EGUs and for oil-fired EGUs
(except those in the limited use liquid oil-fired EGU subcategory). The
Agency received comments that some PM CEMS that are currently
correlated for the 0.030 lb/MMBtu fPM emission limit may experience
some difficulties should re-correlation be necessary at a lower fPM
standard. Based on these comments and on additional review of PM CEMS
test reports, as mentioned in sections IV.C.2. and IV.D.2., the Agency
has made minor technical revisions to shift the basis of correlation
testing from sampling a minimum volume per run to collecting a minimum
mass or minimum sample volume per run and has adjusted the quality
assurance (QA) criterion otherwise associated with the new emission
limit. These changes will enable PM CEMS to be properly certified for
use in demonstrating compliance with the lower fPM standard with a high
degree of accuracy and reliability.
C. What key comments did we receive on the filterable PM and compliance
options, and what are our responses?
1. Comments on the Filterable PM Emission Standard
Comment: Some commenters supported the proposed fPM limit of 0.010
lb/MMBtu as reasonable and achievable, noting that this limit is
slightly greater than the fPM emission limit required for new and
reconstructed units. Additionally, commenters stated CAA section 112
was intended to improve the performance of lagging industrial sources
and that a
[[Page 38521]]
standard that falls far behind what the vast majority of sources have
already achieved, as the current standard does, is inadequate. Other
commenters opposed the proposed fPM limit of 0.010 lb/MMBtu as too
stringent. For instance, some commenters stated that the EPA did not
provide adequate support for the proposed limit. Other commenters
stated that the fact that the vast majority of units are achieving
emission rates below the current limit does not constitute
``developments in practices, processes, and control technologies.''
Response: The EPA disagrees that the Agency has not adequately
supported the proposed fPM limit. As described in the proposal
preamble, the Agency conducted a review of the 2020 Technology Review
pursuant to CAA section 112(d)(6), which focused on identifying and
evaluating developments in practices, processes, and control
technologies for the emission sources in the source category that
occurred since promulgation of the 2012 MATS Final Rule. Based on that
review, the EPA found that a majority of sources were not only
reporting fPM emissions significantly below the current emission limit,
but also that the fleet achieved lower fPM rates at lower costs than
the EPA estimated when it promulgated the 2012 MATS Final Rule. The EPA
explains these findings in more detail in section IV.D.1. of this
preamble and elsewhere in the record. Further, the EPA finds that there
are technological developments and improvements in PM control
technology, which also controls non-Hg HAP metals, since the 2012 MATS
Final Rule that informed the 2023 Proposal and this action, as
discussed further in section IV.D.1. below. For example, industry has
implemented ``best practices'' for monitoring ESP operation more
carefully, and more durable materials have been adopted for FFs since
the 2012 MATS Final Rule. The EPA also finds that these are cognizable
developments for purposes of CAA section 112(d)(6). As other commenters
noted, in National Association for Surface Finishing v. EPA, 795 F.3d
1, 11 (D.C. Cir. 2015), the D.C. Circuit found that the EPA
``permissibly identified and took into account cognizable
developments'' based on the EPA's interpretation of the term as ``not
only wholly new methods, but also technological improvements.''
Similarly, here the EPA identified a clear trend in control efficiency,
costs, and technological improvements, which the EPA is accounting for
in this action. Further, as discussed elsewhere in this section and in
section IV.D.1. of this preamble, the EPA finds case law and
substantial administrative precedent support the EPA's decision to
update the fPM limit based upon these developments.
Comment: Many commenters recommended that the EPA add a compliance
margin in its achievability assumptions. These commenters conveyed that
most EGUs typically operate well below the limit to allow for a
compliance margin in the event of an equipment malfunction or failure,
which they encouraged the EPA to consider when setting new limits.
These commenters claimed that with a proposed fPM limit of 0.010 lb/
MMBtu, an appropriate design margin of 20 percent necessitates that
control technologies must be able to achieve a limit of 0.008 lb/MMBtu
or lower in practice. They also expressed concerns that the EPA did not
take design margin into consideration in the cost analysis. They stated
that by not including the need for a design margin, which the EPA has
acknowledged the need for in at least two of the Agency's publications
(NESHAP Analysis of Control Technology Needs for Revised Proposed
Emission Standards for New Source Coal-fired EGUs, Document ID No. EPA-
HQ-OAR-2009-0234-20223 and PM CEMS Capabilities Summary for Performance
Specification 11, NSPS, and MACT Rules, Document ID No. EPA-HQ-OAR-
2018-0794-5828), the EPA underpredicted the number of units that would
require retrofits. These commenters stated that the combination of a
very low fPM limit and having to account for the measurement
uncertainty and correlation methodology of PM CEMS would likely
necessitate an ``operational target limit'' of 50 percent of the
applicable limit. Some commenters referenced the National Rural
Electric Cooperative Association (NRECA) technical evaluation for the
2023 Proposal titled Technical Comments on National Emissions Standard
for Hazardous Air Pollutants: Coal- and Oil-fired Electric Utility
Steam Generating Units Review of Residual Risk and Technology.\13\ They
said that, even using the EPA's unrealistic ``baseline fPM rates'' and
the lowest possible compliance margin of 20 percent, the NRECA
technical evaluation estimated that 37 units--almost twice as many as
the EPA's estimate--would be required to take substantial action to
comply with the proposed limit.
---------------------------------------------------------------------------
\13\ Technical Comments on National Emission Standards for
Hazardous Air Pollutants: Coal- and Oil-fired Electric Utility Steam
Generating Units Review of Residual Risk and Technology.
Cichanowicz, et al. June 19, 2023. Attachment A to Document ID No.
EPA-HQ-OAR-2018-0794-5994.
---------------------------------------------------------------------------
Response: The EPA agrees that most facility operators normally
target an emission level below the emission limit by incorporating a
compliance margin or margin of error in case of equipment malfunctions
or failures. As the commenters noted, the Agency has previously
recognized that some operators target an emission level 20 to 50
percent below the limit. However, no commenters provided data to
suggest that ESPs or FF are unable to achieve a lower fPM limit.
Furthermore, the Agency does not prescribe specifically how an EGU
controls its emissions or how the unit operates. The choice to target a
lower-level emission rate for a compliance margin is the sole decision
of owners and operators. For facilities with more than one EGU in the
same subcategory, owners or operators may find emissions averaging (40
CFR 63.10009), coupled with or without a compliance margin, could help
the facility attain and maintain emission limits as an effective, low-
cost approach. Additionally, no commenters provided data to indicate
that every owner or operator aims to comply with the fPM limit with the
same compliance margin. Because some operators might aim for a larger
compliance margin than others, it would be difficult to select a
particular assumption about compliance margin for the cost analysis.
Every operator plans for compliance differently and the EPA cannot know
every operator's plans for a compliance margin. Even if the EPA were to
assume a 20 percent compliance margin in its evaluation of PM controls,
the results of the analysis would not change the EPA's decision to
adopt a lower fPM limit. Specifically, a 20 percent compliance margin
assumption to a fPM limit of 0.010 lb/MMBtu would increase the number
of affected EGUs from 33 to 53 (14.1 to 23.9 GW affected capacity) and
the annual compliance costs from $87.2M to $147.7M. The number of EGUs
that demonstrated an ability to meet the lower fPM limit, but do not do
so on average and therefore would require O&M, would increase from 17
to 27 (including the compliance margin). Similarly, the number of ESP
upgrades (previously 11) and bag upgrades (previously 3) would also
increase (to 20 and 4, respectively). There would be no change in the
number of new FF installs. Therefore, cost-effectiveness values for fPM
and individual and total non-Hg HAP metals would only increase
slightly. Moreover, the 30-boiler operating day averaging period using
PM CEMS for compliance
[[Page 38522]]
demonstration provides flexibility for owners and operators to account
for equipment malfunctions, operational variability, and other issues.
Lastly, as described in the 2023 Proposal, and updated here, the vast
majority of coal-fired EGUs are reporting fPM emissions well below the
revised fPM limit. For instance, the median fPM rate of the 296 coal-
fired EGUs assessed in the 2024 Technical Memo is 0.004 lb/MMBtu,\14\
or 60 percent below the revised fPM limit of 0.010 lb/MMBtu. The median
fPM rate of a quarter of the best performing sources (N=74) is 0.002
lb/MMBtu, about 80 percent below the revised fPM limit of 0.010 lb/
MMBtu. Therefore, for these reasons, the EPA disagrees with commenters
that a compliance margin needs to be considered in the cost analysis.
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\14\ For the revised fPM analysis, the EPA uses two methods to
assess the performance of the fleet: average and the 99th percentile
of the lowest quarter of data. Values reported here use the average
fPM rate for each EGU.
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The updated PM analysis, detailed in the memorandum 2024 Update to
the 2023 Proposed Technology Review for the Coal- and Oil-Fired EGU
Source Category (``2024 Technical Memo'') available in the docket,
estimates that the number of EGUs that will need to improve their fPM
emission rate to achieve a 0.010 lb/MMBtu limit has increased from the
20 EGUs assumed in the 2023 Proposal to 33 EGUs, which is more
consistent with the NRECA technical evaluation estimate of 37 EGUs.
This increase is a result of updated methodology that utilizes both the
lowest achieved fPM rate (i.e., the lowest quarter's 99th percentile)
and the average fPM rate across all quarterly data when assessing PM
upgrade and costs assumptions for the evaluated limits. The Agency
disagrees with the commenters, however, that the 37 EGUs in the NRECA
technical evaluation would require ``substantial action to comply with
the proposed standard.'' In the Agency's revised analysis, only 13 EGUs
would require capital investments to meet a fPM limit of 0.010 lb/
MMBtu. Of these, only two EGUs at one facility (Colstrip) currently
without the most effective PM controls are projected to require
installation of a FF, the costliest PM control upgrade option, to meet
0.010 lb/MMBtu. The remaining nine EGUs projected by the EPA to require
capital investments are estimated to require various levels of ESP
upgrades. The EPA estimates that more than half (20 EGUs) would be able
to comply without any capital investments and would instead require
improvements to their existing FF or ESP as they have already
demonstrated the ability to meet the limit, but do not do so on
average.
Comment: Some commenters stated that cost effectiveness is an
important consideration in technology reviews under CAA section
112(d)(6) and acknowledged that the EPA undertook cost-effectiveness
analyses for the three fPM standards on which the Agency sought
comment. However, the commenters stated, the NRECA technical evaluation
found meaningful errors in the EPA's cost analysis, including
unreasonably low capital cost estimates for ESP rebuilds and a failure
to consider the variability of fPM due to changes in operation or
facility design, by not utilizing a compliance margin. They asserted
that these errors resulted in sizeable cost-effectiveness
underestimates that eroded the EPA's overall determination that the
proposed fPM limit is cost-effective. These commenters also asserted
that the EPA's rationale was arbitrary on its face because it reversed,
without explanation, the EPA's prior acknowledgements that a cost-
effectiveness analysis should account for the cost effectiveness of
controls at each affected facility and not simply on an aggregate
nationwide basis. They stated that facility-specific costs should
factor into the EPA's assessment of what is ``necessary'' pursuant to
the provisions of CAA section 112(d)(6) and CAA section 112(f)(2).
Some commenters asserted that, even using the EPA's cost-
effectiveness figures, the proposed 0.010 lb/MMBtu limit is not cost-
effective. These commenters stated that the EPA's proposal to revise
the fPM standard to 0.010 lb/MMBtu based on a cost-effectiveness
estimate of up to $14.7 million per ton of total non-Hg HAP metals
removed (equivalent to $44,900 per ton of fPM removed) is inconsistent
with the EPA's prior actions because the cost-effectiveness estimate is
substantially higher than estimates the Agency has previously found to
be not cost-effective. They further said that, in the past, the EPA has
decided against revising fPM standards based on cost-effectiveness
estimates substantially lower than the cost-effectiveness estimates
here. They said that the EPA should follow these precedents and
acknowledge that $12.2 to $14.7 million per ton of non-Hg HAP metals
reduced is not cost-effective. They argued that the Agency should not
finalize the proposed standard of 0.010 lb/MMBtu for that reason.
Further, these commenters argued that the alternative, more stringent
limit of 0.006 lb/MMBtu is even less cost-effective at $25.6 million
per ton of non-Hg HAP metals reduced, so it should not be considered
either.
The commenters provided the following examples of previous
rulemakings where EPA found controls to not be cost-effective:
<bullet> In the Petroleum Refinery Sector technology review,\15\
the EPA declined to revise the fPM emission limit for existing fluid
catalytic cracking units after finding that it would cost $10 million
per ton of total non-Hg HAP metals reduced (in that case, equivalent to
$23,000 per ton of fPM reduced), which was not cost-effective.
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\15\ Petroleum Refinery Sector Risk and Technology Review and
New Source Performance Standards, 80 FR 75178, 75201 (December 1,
2015).
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<bullet> In the Iron Ore Processing technology review,\16\ the EPA
declined to revise the non-Hg HAP metals limit after finding that
installing wet scrubbers would cost $16 million per ton of non-Hg HAP
metals reduced, which was not cost-effective.
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\16\ National Emission Standards for Hazardous Air Pollutants:
Taconite Iron Ore Processing Residual Risk and Technology Review, 85
FR 45476, 45483 (July 28, 2020).
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<bullet> In the Integrated Iron and Steel Manufacturing Facilities
technology review,\17\ the EPA declined to revise the non-Hg HAP metals
limit after finding that upgrading all fume/flame suppressants at blast
furnaces to baghouses would cost $7 million per ton of non-Hg HAP
metals reduced, which was not cost-effective. The Agency made a similar
finding for a proposed limit that would have cost $14,000 per ton of
volatile HAP reduced.
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\17\ National Emission Standards for Hazardous Air Pollutants:
Integrated Iron and Steel Manufacturing Facilities Residual Risk and
Technology Review, 85 FR 42074, 42088 (July 13, 2020).
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<bullet> In the Portland Cement Manufacturing beyond-the-floor
analysis,\18\ the EPA declined to impose a more stringent non-Hg HAP
metals limit because it resulted in ``significantly higher cost
effectiveness for PM than EPA has accepted in other NESHAP.'' The EPA
noted in that rulemaking that it had previously ``reject[ed] $48,501
per ton of PM as not cost-effective for PM,'' and noted prior EPA
statements in a subsequent rulemaking providing that $268,000 per ton
of HAP removed was a higher cost-effectiveness estimate than the EPA
had accepted in other NESHAP rulemakings.
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\18\ National Emission Standards for Hazardous Air Pollutants
for the Portland Cement Manufacturing Industry and Standards of
Performance for Portland Cement Plants, 78 FR 10006, 10021 (February
12, 2013).
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In contrast, other commenters focused on the EPA's estimated cost-
effective estimates for fPM (which is a surrogate for non-Hg HAP
metals) and argued that
[[Page 38523]]
those estimates were substantially lower than estimates that the EPA
has considered to be cost-effective in other technology reviews.
Therefore, these commenters concluded that the EPA should strengthen
the limit to at least 0.010 lb/MMBtu. These commenters also pointed to
a 2023 report by Andover Technology Partners \19\ that found that the
cost to comply with an emission limit of 0.006 lb/MMBtu on a fleetwide
basis was significantly less than the costs estimated by the EPA.
Andover Technology Partners attributed this difference ``to the
assumptions EPA made regarding the potential emission reductions from
ESP upgrades, which result in a much higher estimate of baghouse
retrofits in EPA's analysis for an emission rate of 0.006 lb/MMBtu.''
These commenters stated that meeting the lower emission limit of 0.006
lb/MMBtu is technologically feasible using currently available
controls, and they urged the EPA to adopt this limit. They stated that
although cost effectiveness is less relevant in the CAA section 112
context than for other CAA provisions, the $103,000 per ton of fPM and
$209,000 per ton of filterable fine PM<INF>2.5</INF> estimates that the
EPA calculated for the 0.006 lb/MMBtu limit were reasonable and
comparable to past practice in technology reviews under CAA section
112(d)(6). They noted that the EPA has previously found a control
measure that resulted in an inflation-adjusted cost of $185,000 per ton
of PM<INF>2.5</INF> reduced to be cost-effective for the ferroalloys
production source category \20\ and proposed a limit for secondary lead
smelting sources that cost an inflation-adjusted $114,000 per ton of
fPM reduced.\21\ They argued that, using the Andover Technology
Partners cost estimates, the 0.006 lb/MMBtu limit has even better cost-
effectiveness estimates at about $72,000 per ton of fPM reduced and
$146,000 per ton of filterable PM<INF>2.5</INF> reduced. These
commenters noted that the EPA also calculated cost effectiveness based
on allowable emissions (i.e., assuming emission reductions achieved if
all evaluated EGUs emit at the maximum allowable amount of fPM, or
0.030 lb/MMBtu) at $1,610,000 per ton, showing that a limit of 0.006
lb/MMBtu allows far less pollution at low cost to the power sector.
They concluded that all these metrics and approaches to considering
costs show that a fPM limit of 0.006 lb/MMBtu would require cost-
effective reductions and can be achieved at a reasonable cost that
would not jeopardize the power sector's function.
---------------------------------------------------------------------------
\19\ Assessment of Potential Revisions to the Mercury and Air
Toxics Standards. Andover Technology Partners. June 15, 2023. Docket
ID No. EPA-HQ-OAR-2018-0794. Also available at <a href="https://www.andovertechnology.com/wp-content/uploads/2023/06/C_23_CAELP_Final.pdf">https://www.andovertechnology.com/wp-content/uploads/2023/06/C_23_CAELP_Final.pdf</a>.
\20\ National Emission Standards for Hazardous Air Pollutants:
Ferroalloys Production, 80 FR 37381 (June 30, 2015).
\21\ National Emission Standards for Hazardous Air Pollutants:
Secondary Lead Smelting, 76 FR 29032 (May 19, 2011).
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Additionally, some commenters cited Sierra Club v. Costle, 657 F.2d
298, 330 (D.C. Cir. 1981), and said the case supports the EPA's
discretion to weigh cost, energy, and environmental impacts,
recognizing the Agency's authority to take these factors into account
``in the broadest sense at the national and regional levels and over
time as opposed to simply at the plant level in the immediate
present.'' These commenters said that the EPA has the authority to
require costs that are reasonable for the industry even if they are not
reasonable for every facility. These commenters acknowledged that the
EPA has discretion to consider cost effectiveness under CAA section
112(d)(2), citing NRDC v. EPA, 749 F.3d 1055, 1060-61 (D.C. Cir. 2014),
but argued that the dollar-per-ton cost-effectiveness metric is less
relevant under CAA section 112 than under other CAA provisions because
the Agency is not charged with equitably distributing the costs of
emission reductions through a uniform compliance strategy, as the EPA
has done in its transport rules. The commenters concluded that the
Agency should require maximum reductions of HAP emissions from each
regulated source category and has no authority to balance cost
effectiveness across industries.
Response: In this action, the EPA is acting under its authority in
CAA section 112(d)(6) to ``review, and revise as necessary (taking into
account developments in practices, processes, and control
technologies), emission standards'' promulgated under CAA section 112.
As the EPA explained in the 2023 Proposal, this technology review is
separate and distinct from other standard-setting provisions under CAA
section 112, such as establishing MACT floors, conducting the beyond-
the-floor analysis, and reviewing residual risk.
Regarding the comments that the EPA underestimated costs to an
extent that undermines the EPA's overall cost-effectiveness
assumptions, the EPA disagrees that the Agency underestimated the
typical costs of ESP rebuilds. The commenters provided cost examples
from only two facilities to support their assertions regarding the
costs of ESP rebuilds. The costs provided for one of those facilities,
Labadie, were not the costs associated with an ESP rebuild, but instead
were the costs associated with the full replacement of an ESP. The
commenter stated that, ``Ameren retrofitted the entire ESP trains on
two units in 2014/2015. On each of these units two of the three
original existing ESPs had to be abandoned and one of the existing ESPs
was retrofitted with new power supplies and flue gas flow
modifications. A new state-of-the-art ESP was added to each unit to
supplement the retrofitted ESPs.'' An ESP replacement is different from
an ESP rebuild, and therefore the costs of an ESP replacement do not
inform the costs of an ESP rebuild. The ESP rebuild cost provided for
the other facility, Petersburg, was less than the EPA's final
assumption regarding the typical cost of an ESP rebuild on a capacity-
weighted average basis. Neither of these examples provided by the
commenter demonstrate that the EPA underestimated costs. For these
reasons, the EPA disagrees with these commenters. Additionally, the EPA
disagrees with these commenters that the Agency must add a compliance
margin in its cost assumptions. As described above, the Agency does not
prescribe specifically how an EGU must be controlled or how it must be
operated, and the choice of overcompliance is at the sole discretion of
the owners and operators.
Generally, the EPA agrees with commenters that cost effectiveness,
i.e., the costs per unit of emissions reduction, is a metric that the
EPA consistently considers, often alongside other cost metrics, in CAA
section 112 rulemakings where it can consider costs, e.g., beyond-the-
floor analyses and technology reviews, and agrees with commenters who
recognize that the Agency has discretion in how it considers statutory
factors under CAA section 112(d)(6), including costs. See e.g.,
Association of Battery Recyclers, Inc. v. EPA, 716 F.3d 667, 673-74
(D.C. Cir. 2013) (allowing that the EPA may consider costs in
conducting technology reviews under CAA section 112(d)(6)); see also
Nat'l Ass'n for Surface Finishing v. EPA, 795 F.3d 1, 11 (D.C. Cir.
2015). The EPA acknowledges that the cost-effectiveness values for
these standards are higher than cost-effectiveness values that the EPA
concluded were not cost-effective and weighed against implementing more
stringent standards for some prior rules. The EPA disagrees, however,
that there is any particular threshold that renders
[[Page 38524]]
a rule cost-effective or not.\22\ The EPA's prior findings about cost
effectiveness in other rules were specific to those rulemakings and the
industries at issue in those rules. As commenters have pointed out, in
considering cost effectiveness, the EPA will often consider what
estimates it has deemed cost-effective in prior rulemakings. However,
the EPA routinely views cost effectiveness in light of other factors,
such as other relevant costs metrics (e.g., total costs, annual costs,
and costs compared to revenues), impacts to the regulated industry, and
industry-specific dynamics to determine whether there are
``developments in practices, processes, and control technologies'' that
warrant updates to emissions standards pursuant to CAA section
112(d)(6). Some commenters, pointing to prior CAA section 112
rulemakings where the EPA chose not to adopt more stringent controls,
mischaracterized cost effectiveness as the sole criterion in those
decisions. These commenters omitted any discussion of other relevant
factors from those rulemakings that, in addition to cost effectiveness,
counseled the EPA against adopting more stringent standards. For
example, in the 2014 Ferroalloys rulemaking that commenters cited to,
the EPA rejected a potential control option due to questions about
technical feasibility and significant economic impacts the option would
create for the industry, including potential facility closures that
would impact significant portions of industry production.\23\ In
contrast here, the controls at issue are technically feasible (they are
used at facilities throughout the country) and will not have
significant effects on the industry. Indeed, the EPA does not project
that the final revisions to MATS will result in incremental changes in
operational coal-fired capacity.
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\22\ See e.g., National Emissions Standards for Hazardous Air
Pollutants: Ferroalloys Production, 80 FR 37366, 37381 (June 30,
2015) (``[I]t is important to note that there is no bright line for
determining acceptable cost effectiveness for HAP metals. Each
rulemaking is different and various factors must be considered.'').
\23\ National Emission Standards for Hazardous Air Pollutants:
Ferroalloys Production, 79 FR 60238, 60273 (October 6, 2014).
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Similarly, in the other rulemakings these commenters pointed to,
where the EPA found similar cost-effectiveness values to those that the
EPA identified for the revised fPM standard here, there are distinct
aspects of those rulemakings and industries that distinguish those
prior actions from this rulemaking. In the 2015 Petroleum Refineries
rulemaking, the EPA considered the cost effectiveness of developments
at only two facilities to decide whether to deploy a standard across
the much wider industry.\24\ Here in contrast, the EPA is basing
updates to fPM standards for coal-fired EGUs on developments across the
majority of the industry and the performance of the fleet as a whole,
which has demonstrated the achievability of a more stringent standard.
Additionally, there are inherent differences between the power sector
and other industries that similarly distinguish prior actions from this
rulemaking. For example, because of the size of the power sector (314
coal-fired EGUs at 157 facilities), and because this source category is
one of the largest stationary source emitters of Hg, arsenic, and HCl
and is one of the largest regulated stationary source emitters of total
HAP,\25\ even considering that this rule affects only a fraction of the
sector, the estimated HAP reductions in this final rule (8.3 tpy) are
higher than those in the prior rulemakings cited by the commenters (as
are the estimated PM reductions (2,537 tpy) used as a surrogate for
non-Hg HAP metals). In contrast, in the 2020 Integrated Iron and Steel
Manufacturing rulemaking, the source category covered included only 11
facilities, and the estimated reductions the EPA considered would have
removed 3 tpy of HAP and 120 tpy of PM.\26\ Likewise, in the 2013
Portland Cement rulemaking, the EPA determined not to pursue more
stringent controls for the sector after finding the standard would only
result in 138 tpy of nationwide PM reductions and that there was a high
cost for such modest reductions.\27\ Here, the EPA estimates
significantly greater HAP emission reductions, and fPM emission
reductions that are orders of magnitude greater than both prior
rulemakings.\28\
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\24\ Petroleum Refinery Sector Risk and Technology Review and
New Source Performance Standards, 80 FR 75178, 75201 (December 1,
2015).
\25\ 2020 National Emissions Inventory (NEI) Data; <a href="https://www.epa.gov/air-emissions-inventories/2020-national-emissions-inventory-nei-data">https://www.epa.gov/air-emissions-inventories/2020-national-emissions-inventory-nei-data</a>.
\26\ National Emission Standards for Hazardous Air Pollutants:
Integrated Iron and Steel Manufacturing Facilities Residual Risk and
Technology Review, 85 FR 42074, 42088 (July 13, 2020).
\27\ National Emission Standards for Hazardous Air Pollutants
for the Portland Cement Manufacturing Industry and Standards of
Performance for Portland Cement Plants, 78 FR 10006, 10020-10021
(February 12, 2013).
\28\ In addition, while commenters are correct that the EPA
determined not to adopt more stringent controls under the iron ore
processing technology review, the aspects of the rulemaking that the
commenters cite to concerned whether additional controls were
necessary to provide an ample margin of safety under a residual risk
review. In that instance, the EPA determined not to implement more
stringent standards under the risk review based on the installation
of wet ESPs in addition to wet scrubbers, based on the EPA's
determination that such improvements were not necessary to provide
an ample margin of safety to protect public health. See National
Emission Standards for Hazardous Air Pollutants: Taconite Iron Ore
Processing Residual Risk and Technology Review, 84 FR 45476, 45483
(July 28, 2020).
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There are also unique attributes of the power sector that the EPA
finds support the finalization of revised standards for fPM and non-Hg
HAP metals despite the relatively high cost-effectiveness values of
this rulemaking as compared to other CAA section 112 rulemakings. As
the EPA has demonstrated throughout this record, there are hundreds of
EGUs regulated under MATS with well-performing control equipment that
are already reporting emission rates below the revised standards,
whereas only a handful of facilities with largely outdated or
underperforming controls are emitting significantly more than their
peers. That means that the communities located near these handful of
facilities may experience exposure to higher levels of toxic metal
emissions than communities located near similarly sized well-controlled
plants. This is what the revised standards seek to remedy, and as
discussed throughout this record, this goal is consistent with the
EPA's authority under CAA section 112(d)(6) and the purpose of CAA
section 112 more generally.
U.S. EGUs are a major source of HAP metals emissions including
arsenic, beryllium, cadmium, chromium, cobalt, lead, nickel, manganese,
and selenium. Some HAP metals emitted by U.S. EGUs are known to be
persistent and bioaccumulative and others have the potential to cause
cancer. Exposure to these HAP metals, depending on exposure duration
and levels of exposures, is associated with a variety of adverse health
effects. These adverse health effects may include chronic health
disorders (e.g., irritation of the lung, skin, and mucus membranes;
decreased pulmonary function, pneumonia, or lung damage; detrimental
effects on the central nervous system; damage to the kidneys; and
alimentary effects such as nausea and vomiting). The emissions
reductions projected under this final rule from the use of PM controls
are expected to reduce exposure of individuals residing near these
facilities to non-Hg HAP metals, including carcinogenic HAP.
EGUs projected to be impacted by the revised fPM standards
represent a small fraction of the total number of the coal-fired EGUs
(11 percent for the 0.010 lb/MMBtu fPM limit). In addition, many
regulated facilities are electing to retire
[[Page 38525]]
due to factors independent of the EPA's regulations, and the EPA
typically has more information on plant retirements for this sector
than other sectors regulated under CAA section 112. Both of these
factors contribute to relatively higher cost-effectiveness estimates in
this rulemaking as compared to other sectors where the EPA is not able
to account for facility retirements and factor in shorter amortization
periods for the price of controls.
While some commenters stated that meeting an even lower emission
limit of 0.006 lb/MMBtu is technologically feasible using currently
available controls, the Agency declines to finalize this limit
primarily due to the technological limitations of PM CEMS at this lower
emission limit (as discussed in more detail in sections IV.C.2. and
IV.D.2. below). Additionally, the EPA considered the higher costs
associated with a more stringent standard as compared to the final
standard presented in section IV.D.1.
Finally, as mentioned in the Response to Comments document, the EPA
finds that use of PM CEMS, which provide continuous feedback with
respect to fPM variability, in lieu of quarterly fPM emissions testing,
will render moot the commenter's suggestion that margin of compliance
has not been taken into account.
Comment: Some commenters argued that the low residual risks the EPA
found in its review of the 2020 Residual Risk Review obviate the need
for the EPA to revise the standards under the separate technology
review, and that residual risk should be a relevant aspect of the EPA's
technology review of coal- and oil-fired EGUs. These commenters argued
that it is arbitrary and capricious for the EPA to impose high costs on
facilities, which they claimed will only result in marginal emission
reductions, when the EPA determined there is not an unreasonable risk
to the environment or public health.
Other commenters agreed with the EPA's ``two-pronged''
interpretation that CAA section 112(d)(6) provides authorities to the
EPA that are distinct from the EPA's risk-based authorities under CAA
section 112(f)(2). These commenters said that if the criteria under CAA
section 112(d)(6) are met, the EPA must update the standards to reflect
new developments independent of the risk assessment process under CAA
section 112(f)(2). They said the technology-based review conducted
under CAA section 112(d)(6) need not account for any information
learned during the residual risk review under CAA section 112(f)(2)
unless that information pertains to statutory factors under CAA section
112(d)(6), such as costs. They concluded that CAA section 112(d)(6)
requires the EPA to promulgate the maximum HAP reductions possible
where achievable at reasonable cost and is separate from the EPA's
residual risk analysis.
Response: The EPA has an independent statutory authority and
obligation to conduct the technology review separate from the EPA's
authority to conduct a residual risk review, and the Agency agrees with
commenters that recognized that the EPA is not required to account for
information obtained during a residual risk review in conducting a
technology review. The EPA's finding that there is an ample margin of
safety under the residual risk review in no way interferes with the
EPA's obligation to require more stringent standards under the
technology review where developments warrant such standards. The D.C.
Circuit has recognized the CAA section 112(d)(6) technology review and
112(f)(2) residual review are ``distinct, parallel analyses'' that the
EPA undertakes ``[s]eparately.'' Nat'l Ass'n for Surface Finishing v.
EPA, 795 F.3d 1, 5 (D.C. Cir. 2015). In other recent residual risk and
technology reviews, the EPA determined additional controls were
warranted under technology reviews pursuant to CAA section 112(d)(6)
although the Agency determined additional standards were not necessary
to maintain an ample margin of safety under CAA section 112(f)(2).\29\
The EPA has also made clear that the Agency ``disagree[s] with the view
that a determination under CAA section 112(f) of an ample margin of
safety and no adverse environmental effects alone will, in all cases,
cause us to determine that a revision is not necessary under CAA
section 112(d)(6).'' \30\ While the EPA has considered risks as a
factor in some previous technology reviews,\31\ that does not compel
the Agency to do so in this rulemaking. Indeed, in other instances, the
EPA has adopted the same standards under both CAA sections 112(f)(2)
and 112(d)(6) based on independent rationales where necessary to
provide an ample margin of safety and because it is technically
appropriate and necessary to do so, emphasizing the independent
authority of the two statutory provisions.\32\
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\29\ See, e.g., National Emission Standards for Hazardous Air
Pollutants: Refractory Products Manufacturing Residual Risk and
Technology Review, 86 FR 66045 (November 19, 2021); National
Emission Standards for Hazardous Air Pollutants: Site Remediation
Residual Risk and Technology Review, 85 FR 41680 (July 10, 2020);
National Emission Standards for Hazardous Air Pollutants: Organic
Liquids Distribution (Non-Gasoline) Residual Risk and Technology
Review, 85 FR 40740, 40745 (July 7, 2020); National Emission
Standards for Hazardous Air Pollutants: Generic Maximum Achievable
Control Technology Standards Residual Risk and Technology Review for
Ethylene Production, 85 FR 40386, 40389 (July 6, 2020); National
Emission Standards for Hazardous Air Pollutants for Chemical
Recovery Combustion Sources at Kraft, Soda, Sulfite, and Stand-Alone
Semichemical Pulp Mills, 82 FR 47328 (October 11, 2017); National
Emission Standards for Hazardous Air Pollutants: Generic Maximum
Achievable Control Technology Standards; and Manufacture of Amino/
Phenolic Resins, 79 FR 60898, 60901 (October 8, 2014).
\30\ National Emission Standards for Hazardous Air Pollutant
Emissions: Group I Polymers and Resins; Marine Tank Vessel Loading
Operations; Pharmaceuticals Production; and the Printing and
Publishing Industry, 76 FR 22566, 22577 (April 21, 2011).
\31\ See, e.g., National Emission Standards for Organic
Hazardous Air Pollutants From the Synthetic Organic Chemical
Manufacturing Industry, 71 FR 76603, 76606 (December 21, 2006); see
also Proposed Rules: National Emission Standards for Halogenated
Solvent Cleaning, 73 FR 62384, 62404 (October 20, 2008).
\32\ National Emissions Standards for Hazardous Air Pollutants:
Secondary Lead Smelting, 77 FR 556, 564 (January 5, 2012).
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The language and structure of CAA section 112, along with its
legislative history, further underscores the independent nature of
these two provisions.\33\ While the EPA is only required to undertake
the risk review once (8 years after promulgation of the original MACT
standards), it is required to undertake the technology review multiple
times (at least every 8 years after promulgation of the original MACT
standard). That Congress charged the EPA to ensure an ample margin of
safety through the risk review, yet still required the technology
review to be conducted on a periodic basis, demonstrates that Congress
anticipated that the EPA would strengthen standards based on
technological developments even after it had concluded there was an
ample margin of safety. CAA section 112's overarching charge to the EPA
to ``require the maximum degree of reduction in emissions of the
hazardous air pollutants subject to this section (including a
prohibition on such emissions)'' further demonstrates that Congress
sought to minimize the emission of hazardous air pollution wherever
feasible independent of a finding of risk. Moreover, as discussed
supra, in enacting the 1990 CAA Amendments, Congress purposefully
replaced the previous risk-based approach to establishing standards for
HAP with a technology-driven approach. This technology-driven
[[Page 38526]]
approach recognizes the ability for the EPA to achieve substantial
reductions in HAP based on technological improvements without the
inherent difficulty in quantifying risk associated with HAP emission
exposure given the complexities of the pathways through which HAP cause
harm and insufficient availability of data to quantify their effects
discussed in section II.B.2. Independent of risks, it would be
inconsistent with the text, structure, and legislative history for the
EPA to conclude that Congress intended the statute's technology-based
approach to be sidelined after the EPA had concluded the risk review.
---------------------------------------------------------------------------
\33\ See section II.A.2. above for further discussion of the
statutory structure and legislative history of CAA section 112.
---------------------------------------------------------------------------
Comment: Some commenters expressed concern that some portion of
affected units could simply retire instead of coming into compliance
with new requirements, potentially occurring before new generation
could be built to replace the lost generation. During this period, a
lack of dispatchable generation could significantly increase the
likelihood of outages, particularly during periods of severe weather.
In addition, some commenters argued that revising the fPM limit was
unnecessary as there is a continuing downward trend in HAP emissions
from early retirements of coal-fired EGUs, whereas accelerating this
trend could have potential adverse effects on reliability. Some
commenters also stated that as more capacity and generation is shifted
away from coal-fired EGUs due to the Inflation Reduction Act (IRA) and
other regulatory and economic factors, the total annual fPM and HAP
emissions from industry will decline, regardless of whether the fPM
limit is made more stringent.
Response: The EPA disagrees that this rule would threaten resource
adequacy or otherwise degrade electric system reliability. Commenters
provided no credible information supporting the argument that this
final rule would result in a significant number of retirements or a
larger amount of capacity needing controls. The Agency estimates that
this rule will require additional fPM control at less than 12 GW of
operable capacity in 2028, which is about 11 percent of the total coal-
fired EGU capacity projected to operate in that year. The units
requiring additional fPM controls are projected to generate less than
1.5 percent of total generation in 2028. Moreover, the EPA does not
project that any EGUs will retire in response to the standards
promulgated in this final rule. Because the EPA projects no incremental
changes in existing operational capacity to occur in response to the
final rule, the EPA does not anticipate this rule will have any
implications for resource adequacy.
Nevertheless, it is possible that some EGU owners may conclude that
retiring a particular EGU and replacing it with new capacity is a more
economic option from the perspective of the unit's customers and/or
owners than making investments in new emissions controls at the unit.
The EPA understands that before implementing such a retirement
decision, the unit's owner will follow the processes put in place by
the relevant regional transmission organization (RTO), balancing
authority, or state regulator to protect electric system reliability.
These processes typically include analysis of the potential impacts of
the proposed EGU retirement on electrical system reliability,
identification of options for mitigating any identified adverse
impacts, and, in some cases, temporary provision of additional revenues
to support the EGU's continued operation until longer-term mitigation
measures can be put in place. No commenter stated that this rule would
somehow authorize any EGU owner to unilaterally retire a unit without
following these processes, yet some commenters nevertheless assume
without any rationale that is how multiple EGU owners would proceed, in
violation of their obligations to RTOs, balancing authorities, or state
regulators relating to the provision of reliable electric service.
In addition, the Agency has granted the maximum time allowed for
compliance under CAA section 112(i)(3) of 3 years, and individual
facilities may seek, if warranted, an additional 1-year extension of
the compliance date from their permitting authority pursuant to CAA
section 112(i)(3)(B). The construction of any additional pollution
control technology that EGUs might install for compliance with this
rule can be completed within this time and will not require significant
outages beyond what is regularly scheduled for typical maintenance.
Facilities may also obtain, if warranted, an emergency order from the
Department of Energy pursuant to section 202(c) of the Federal Power
Act (16 U.S.C. 824a(c)) that would allow the facility to temporarily
operate notwithstanding environmental limits when the Secretary of
Energy determines doing so is necessary to address a shortage of
electric energy or other electric reliability emergency.
Further, despite the comments asserting concerns over electric
system reliability, no commenter cited a single instance where
implementation of an EPA program caused an adverse reliability impact.
Indeed, similar claims made in the context of the EPA's prior CAA
rulemakings have not been borne out in reality. For example, in the
stay litigation over the Cross-State Air Pollution Rule (CSAPR), claims
were made that allowing the rule to go into effect would compromise
reliability. Yet in the 2012 ozone season starting just over 4 months
after the rule was stayed, EGUs covered by CSAPR collectively emitted
below the overall program budgets that the rule would have imposed in
that year if the rule had been allowed to take effect, with most
individual states emitting below their respective state budgets.
Similarly, in the litigation over the 2015 Clean Power Plan, assertions
that the rule would threaten electric system reliability were made by
some utilities or their representatives, yet even though the Supreme
Court stayed the rule in 2016, the industry achieved the rule's
emission reduction targets years ahead of schedule without the rule
ever going into effect. See West Virginia v. EPA, 142 S. Ct. 2587, 2638
(2022) (Kagan, J., dissenting) (``[T]he industry didn't fall short of
the [Clean Power] Plan's goal; rather, the industry exceeded that
target, all on its own . . . . At the time of the repeal . . . `there
[was] likely to be no difference between a world where the [Clean Power
Plan was] implemented and one where it [was] not.' '') (quoting 84 FR
32561). In other words, the claims that these rules would have had
adverse reliability impacts proved to be groundless.
The EPA notes that similar concerns regarding reliability were
raised about the 2012 MATS Final Rule--a rule that projected the need
for significantly greater installation of controls and other capital
investments than this current revision.\34\ As with the current rule,
the flexibility of permitting authorities to allow a fourth year for
compliance was available in a broad range of situations, and in the
event that an isolated, localized concern were to emerge that could not
be addressed solely through the 1-year extension under CAA section
112(i)(3), the CAA provides flexibilities to bring sources into
compliance while maintaining reliability. We have seen no evidence in
the last decade to suggest
[[Page 38527]]
that the implementation of MATS caused power sector adequacy and
reliability problems, and only a handful of sources obtained
administrative orders under the enforcement policy issued with MATS to
provide relief to reliability critical units that could not comply with
the rule by 2016.
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\34\ The EPA projected that the 2012 MATS Final Rule would drive
the installation of an additional 20 GW of dry FGD (dry scrubbers),
44 GW of DSI, 99 GW of additional ACI, 102 GW of additional FFs, 63
GW of scrubber upgrades, and 34 GW of ESP upgrades. While a
subsequent analysis found that the industry ultimately installed
fewer controls than was projected, the control installations that
occurred following the promulgation of the 2012 MATS Final Rule were
still significantly greater than the installations that are
estimated to occur as a result of this final rule (where, for
example, the EPA estimates that less than 2 GW of capacity would
install FF technology for compliance).
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Comment: Commenters suggested that the EPA use its authority to
create subcategories of affected facilities that elect to permanently
retire by the compliance date as the Agency has taken in similar
proposed rulemakings affecting coal- and oil-fired EGUs. Commenters
stated the EPA should subcategorize those sources that have adopted
enforceable retirement dates and not subject those sources to any final
rule requirements. They indicated that the EPA is fully authorized to
subcategorize these units under CAA section 112(d)(1). Commenters asked
that the EPA consider other simultaneous rulemakings, such as the
proposed Greenhouse Gas Standards and Guidelines for Fossil Fuel Power
Plants,\35\ where the EPA proposed that EGUs that elect to shut down by
January 1, 2032, must maintain their recent historical carbon dioxide
(CO<INF>2</INF>) emission rate via routine maintenance and operating
procedures (i.e., no degradation of performance). Commenters also
referenced the retirement date of December 31, 2032, in the EPA Office
of Water's proposed Effluent Limitation Guidelines.\36\
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\35\ 88 FR 33245 (May 23, 2023).
\36\ 88 FR 18824, 18837 (March 29, 2023).
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Commenters claimed that creating a subcategory for units facing
near-term retirements that harmonizes the retirement dates with other
rulemakings would greatly assist companies with moving forward on
retirement plans without running the risk of being forced to retire
early, which could create reliability concerns or, in the alternative,
forced to deliberate whether to install controls and delaying
retirement to recoup investments in the controls. Commenters also
suggested that EGUs with limited continued operation be allowed to
continue to perform quarterly stack testing to demonstrate compliance
with the fPM limitations (rather than having to install PM CEMS).
Commenters suggested that imposing different standards on these
subcategories should continue the status quo for these units until
retirement. Commenters claimed that it would make no sense for the EPA
to require an EGU slated to retire in the near term to expend
substantial resources on controls in the interim since these sources
are very unlikely to find it viable to construct significant control
upgrades for a revised standard that would become effective in mid-
2027, only 5 years before the unit's permanent retirement. Commenters
further noted if the EPA does not establish such a subcategory or take
other action to ensure these units are not negatively impacted by the
rulemaking, the retirement of some units could be accelerated due to
the costs of installing a PM CEMS and the need to rebuild or upgrade an
existing ESP or install a FF to supplement an existing ESP. Commenters
stated that the EPA cannot ignore the need for a coordinated retirement
of thermal generating capacity while new generation sources come online
to avoid detrimental impacts to grid reliability.
Commenters suggested that if the EPA decides to proceed with
finalizing the revised standards in the 2023 Proposal, the Agency
should create a subcategory for coal-fired EGUs that elect by the
compliance date of the revised standards (i.e., mid-2027) to retire the
units by December 31, 2032, or January 1, 2032, if the EPA prefers to
tie the 2023 Proposal to the proposed Emission Guidelines instead of
the Effluent Limitation Guidelines, and maintain the current MATS
standards for this subcategory of units. Commenters requested that the
EPA coordinate the required retirement date for the 2023 Proposal with
other rules so that all retirement dates align. Commenters reiterated
that the EPA has multiple authorities with overlapping statutory
timelines that affect commenters' plans regarding the orderly
retirement of coal-fired EGUs and their ability to continue the
industry's clean energy transformation while providing the reliability
and affordability that their customers demand. Commenters suggested
that EGUs that plan to retire by 2032 should have the opportunity to
seek a waiver from PM CEMS installation altogether and continue
quarterly stack testing during the remaining life of the unit. They
also suggested that if a unit does not retire by the specified date, it
should be required to immediately cease operation or meet the standards
of the rule. Commenters stated that under this recommendation an EGU's
failure to comply would then be a violation of the 2023 Proposal's
final rule subject to enforcement.
Response: In response to commenters' concerns, the EPA evaluated
the feasibility of creating a subcategory for facilities with near-term
retirements but disagrees with commenters that such a subcategory is
appropriate for this rulemaking. In particular, the EPA found that,
based on its own assessment and that of commenters, only a few
facilities would likely be eligible for a near-term retirement
subcategory and that it would not significantly reduce the costs of the
revised standards. According to the EPA's assessment, 67 of the 296
EGUs assessed \37\ have announced retirements between 2029 and 2032--
less than one-quarter of the fleet--and all but three of those EGUs (at
two facilities) have already demonstrated the ability to comply with
the 0.010 lb/MMBtu fPM standard on average. Additionally, these three
EGUs already use PM CEMS to demonstrate compliance, therefore the
comment requesting a waiver of PM CEMS installations for EGUs with
near-term retirements is not relevant. Because the EPA's analysis led
the Agency to conclude that there would be little utility to a near-
term retirement subcategory and it would not change the costs of the
rule in a meaningful way, the EPA determined not to create a retirement
subcategory for the fPM standard. In addition, the EPA notes that
allowing units to operate without the best performing controls for an
additional number of years would lead to higher levels of non-Hg HAP
metals emissions and continued exposure to those emissions in the
communities around these units during that timeframe. Regarding a fPM
compliance requirement subcategory for EGUs with near-term retirements,
the Agency estimates 26 of 67 EGUs are already using PM CEMS for
compliance demonstration and finds that the costs to install PM CEMS
for facilities with near-term retirements are reasonable. The Agency
finds that the transparency provided by PM CEMS and the increased
ability to quickly detect and correct potential control or operational
problems using PM CEMS furthers Congress's goal to ensure that emission
reductions are consistently maintained and makes PM CEMS the best
choice for this rule's compliance monitoring for all EGUs.
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\37\ In this final rule, the EPA reviewed fPM compliance data
for 296 coal-fired EGUs expected to be operational on January 1,
2029. This review is explained in detail in the 2024 Technical Memo.
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2. Comments on the Proposed Changes to the Compliance Demonstration
Options
Comment: The Agency received both supportive and opposing comments
requiring the use of PM CEMS for compliance demonstration. Supportive
commenters stated the EPA must require the use of PM CEMS to monitor
their emissions of non-Hg HAP metals
[[Page 38528]]
as PM CEMS are now more widely deployed than when MATS was first
promulgated, and experience with PM CEMS has enabled operators to more
promptly detect and correct problems with pollution controls as
compared to other monitoring and testing options allowed under MATS
(i.e., periodic stack testing and parametric monitoring for PM),
thereby lowering HAP emissions. They said that the fact that PM CEMS
have been used to demonstrate compliance in a majority of units in the
eight best performing deciles \38\ provides strong evidence that PM
CEMS can be used effectively to measure low levels of PM emissions.
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\38\ Analysis of PM and Hg Emissions and Controls from Coal-
Fired Power Plants. Andover Technology Partners. August 19, 2021.
Document ID No. EPA-HQ-OAR-2018-0794-4583.
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Opposing commenters urged the EPA to retain all current options for
demonstrating compliance with non-Hg HAP metal standards, including
quarterly PM and metals testing, LEE, and PM CPMS. These commenters
said removing these compliance flexibility options goes beyond the
scope of the RTR and does not address why the reasons these options
were originally included in MATS are no longer valid. Commenters said
they have previously raised concerns about PM CEMS that the EPA has
avoided by stating that CEMS are not the only compliance method for PM.
They stated that previously, the EPA has determined these compliance
methods were both adequate and frequent enough to demonstrate
compliance.
Response: The Agency disagrees with commenters who suggests that
the rule should retain all previous options for demonstrating
compliance with either the individual metals, total metals, or fPM
limits. Congress intended for CAA section 112 to achieve significant
reductions of HAP, and the EPA agrees with other commenters that the
use of CEMS in general and PM CEMS in particular enables owners or
operators to detect and quickly correct control device or process
issues in many cases before the issues become compliance problems.
Consistent with the discussion contained in the 2023 Proposal (88 FR
24872), the Agency finds the transparency and ability to quickly detect
and correct potential control or operational problems furthers
Congress's goal to ensure that emission reductions are consistently
maintained and makes PM CEMS the best choice for this rule's compliance
monitoring.
Comment: Some commenters objected to the EPA's proposal to require
the use of PM CEMS for purposes of demonstrating compliance with the
revised fPM standard, stating that the requirements of Performance
Specification 11 of 40 CFR part 60, appendix B (PS-11) will become
extremely hard to satisfy at the low emission limits proposed. For PS-
11, relative correlation audit (RCA), and relative response audit
(RRA), the tolerance interval and confidence interval requirements are
expressed in terms of the emission standard that applies to the source.
The commenters reviewed test data from operating units and found
significantly higher PS-11 failure (>80 percent), RCA failure (>80
percent), and RRA failure (60 percent) rates at the more stringent
proposed emission limits. They stated that the cost, complexity, and
failure rate of equipment calibration remains one of the biggest
challenges with the use of PM CEMS and therefore other compliance
demonstration methods should be retained. Commenters also noted that
repeated tests due to failure could result in higher total emissions
from the units.
Response: The Agency is aware of concerns by some commenters that
PM CEMS currently correlated for the 0.030 lb/MMBtu fPM emission limit
may experience difficulties should re-correlation be necessary; and
those concerns are also ascribed to yet-to-be installed PM CEMS. In
response to those concerns, the Agency has shifted the basis of
correlation testing from requiring only the collection of a minimum
volume per run to also allowing the collection of a minimum mass per
run and has adjusted the QA criterion otherwise associated with the new
emission limit. These changes will ease the transition for coal- and
oil-fired EGUs using only PM CEMS for compliance demonstration
purposes. The first change, allowing the facility to choose either the
collection of a minimum mass per run or a minimum volume per run,
should reduce high-level correlation testing duration, addressing other
concerns about extended runtimes with degraded emissions control or
increased emissions, and should reduce correlation testing costs. The
second change, adjusting the QA criteria, is consistent with other
approaches the Agency has used when lower ranges of instrumentation or
methods are employed. For example, in section 13.2 of Performance
Specification 2 (40 CFR part 60, appendix B) the QA criteria for the
relative accuracy test audit for SO<INF>2</INF> and Nitrogen Oxide CEMS
are relaxed as the emission limit decreases. This is accomplished at
lower emissions by allowing a larger criterion or by modifying the
calculation and allowing a less stringent number in the denominator.
With these changes to the QA criteria and correlation procedures, the
EPA believes EGUs will be able to use PM CEMS to demonstrate compliance
at the revised level of the fPM standard.
Comment: Some commenters asserted that if the EPA finalizes the
requirement to demonstrate compliance using PM CEMS, EGUs will not be
able to comply with a lower fPM limit on a continuous basis and that
accompanying a lower limit with more restrictive monitoring
requirements adds to the regulatory burden of affected sources and
permitting authorities.
Response: The EPA disagrees with commenters' claim that that EGUs
will not be able to demonstrate compliance continuously with a fPM
limit of 0.010 lb/MMBtu. The EPA believes that CEMS in general and PM
CEMS in particular enable owners and operators to detect and quickly
correct control device or process issues in many cases before the
issues become compliance problems. Contrary to the commenter's
assertion that EGUs will not be able to comply with a lower fPM limit
on a continuous basis, as mentioned in the June 2023 Andover Technology
Partners analysis,\39\ over 80 percent of EGUs using PM CEMS for
compliance purposes have already been able to achieve and are reporting
and certifying consistent achievement of fPM rates below 0.010 lb/
MMBtu.\40\ The EPA is unaware of any additional burden experienced by
those EGU owners or operators or their regulatory authorities with
regard to PM CEMS use at these lower emission levels, and does not
expect additional burden to be placed on EGU owners or operators with
regard to PM CEMS from application of the revised emission limit.
However, this final rule incorporates approaches, such as switching
from a minimum sample volume per run to collection of a
[[Page 38529]]
minimum mass sample or mass volume per run and adjusting the PM CEMS QA
acceptability criteria, to reduce the challenges with using PM CEMS.
Moreover, the 30-boiler-operating-day averaging period of the limit
provides flexibility for owners and operators to account for equipment
malfunctions and other issues. Consistent with the discussion in the
2023 Proposal,\41\ the Agency finds that PM CEMS are the best choice
for this rule's compliance monitoring as they provide increased
emissions transparency, ability for EGU owner/operators to quickly
detect and correct potential control or operational problems, and
greater assurance of continuous compliance. While PM CEMS can produce
values at lower levels provided correlations are developed
appropriately, the Agency established the final fPM limit of 0.010 lb/
MMBtu after considering factors such as run times necessary to develop
correlations, potential random error effects, and costs.
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\39\ Assessment of Potential Revisions to the Mercury and Air
Toxics Standards. Andover Technology Partners. June 15, 2023. Docket
ID No. EPA-HQ-OAR-2018-0794. June 2023. Also available at <a href="https://www.andovertechnology.com/wp-content/uploads/2023/06/C_23_CAELP_Final.pdf">https://www.andovertechnology.com/wp-content/uploads/2023/06/C_23_CAELP_Final.pdf</a>.
\40\ See for example the PM CEMS Thirty Boiler Operating Day
Rolling Average Reports for Duke's Roxboro Steam Electric Plant in
North Carolina and at Minnesota Power's Boswell Energy Center in
Minnesota. These reports and those from other EGUs reporting
emission levels at or lower than 0.010 lb/MMBtu are available
electronically by searching in the EPA's Web Factor Information
Retrieval System (WebFIRE) Report Search and Retrieval portion of
the Agency's WebFIRE internet website at <a href="https://cfpub.epa.gov/webfire/reports/esearch.cfm">https://cfpub.epa.gov/webfire/reports/esearch.cfm</a>.
\41\ See 88 FR 24872.
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Comment: Commenters stated that the EPA's cost estimates contradict
the Agency's suggestion that the use of PM CEMS is a more cost-
effective monitoring approach than quarterly testing, especially for
units that qualify as LEE. They said that the EPA used estimates from
the Institute of Clean Air Companies (ICAC) or Envea/Altech which do
not include numerous costs associated with PM CEMS that make them not
cost-effective, such as the cost of intermittent stack testing
associated with the PS-11 correlations and the ongoing costs of RCAs
and RRA, which are a large part of the costs associated with PM CEMS
and would rise substantially in conjunction with the proposed new PM
limits. The commenters said that the ICAC estimated range of PM CEMS
installation costs are particularly understated and outdated and should
be ignored by the Agency. They said that the EPA estimates may also
understate PM CEMS cost by assuming the most commonly used light
scattering based PM CEMS will be used for all applications. The
commenters said that while more expensive, a significant number of beta
gauge PM CEMS are used for MATS compliance, especially where PM spiking
is used for PS-11 correlation and RCA testing and that this higher
degree of accuracy from beta gauge PM CEMS may be needed for sources
without a margin of compliance under the new, more stringent emission
limit.
Response: The EPA disagrees with the commenters' suggestion that
the Agency is required to select the most cost-effective approach for
compliance monitoring. Rather, the Agency selects the approach that
best provides assurance that emission limits are met. PM CEMS annual
costs represent a very small fraction of a typical coal-fired EGU's
operating costs and revenues. As described in the Ratio of Revised
Estimated Non-Beta Gauge PM CEMS EUAC to 2022 Average Coal-Fired EGU
Gross Profit memorandum, available in the docket, if all coal-fired
EGUs were to purchase and install new PM CEMS, the Equivalent Uniform
Annual Cost (EUAC) would represent less than four hundredths of a
percent of the average annual operating expenses from coal-fired EGUs.
Further, as described in the Revised Estimated Non-Beta Gauge PM
CEMS and Filterable PM Testing Costs technical memorandum, available in
the rulemaking docket, the EPA calculated average costs for PM CEMS and
quarterly testing from values submitted by commenters in response to
the proposal's solicitation, which are discussed in section IV.D. of
the preamble. Based on the commenters' suggestions, these revised costs
include the costs of intermittent stack testing associated with the PS-
11 correlations and ongoing costs of RCAs and RRAs. While the average
EUAC for PM CEMS exceeds the average annual cost of quarterly stack
emission testing, the cost for PM CEMS does not include important
additional benefits associated with providing continuous emissions data
to EGU owners or operators, regulators, nearby community members, or
the general public. As a reminder, the EPA is not obligated to choose
the most inexpensive approach for compliance demonstrations,
particularly when all benefits are not monetized, even though costs can
be an important consideration. Consistent with the discussion contained
in the 2023 Proposal at 88 FR 24872, the Agency finds the increased
transparency of EGU fPM emissions and the ability to quickly detect and
correct potential control or operational problems, along with greater
assurance of continuous compliance makes PM CEMS the best choice for
this rule's compliance monitoring.
The Agency acknowledges the commenters' suggestions that EGU owners
or operators may find that using beta gauge PM CEMS is most appropriate
for the lower fPM emission limit in the rule; such suggestions are
consistent with the Agency's view, as expressed in 88 FR 24872.
However, the Agency believes other approaches, including spiking, can
also ease correlation testing for PM CEMS. Moreover, the Agency
anticipates that the new fPM limit will increase demand for, and
perhaps spur increased production of, beta gauge PM CEMS.
D. What is the rationale for our final approach and decisions for the
filterable PM (as a surrogate for non-Hg HAP metals) standard and
compliance demonstration options?
The EPA is finalizing a lower fPM emission standard of 0.010 lb/
MMBtu for coal-fired EGUs, as a surrogate for non-Hg HAP metals, and
the use of PM CEMS for compliance demonstration purposes for coal- and
oil-fired EGUs (with the exception of limited-use liquid oil-fired
EGUs) based on developments in the performance of sources within the
category since the EPA finalized MATS and the advantages conferred by
using CEMS for compliance. As described in the 2023 Proposal, non-Hg
HAP metals are predominately a component of fPM, and control of fPM
results in concomitant reduction of non-Hg HAP metals (with the
exception of Se, which may be present in the filterable fraction or in
the condensable fraction as the acid gas, SeO<INF>2</INF>). The EPA
observes that since MATS was finalized, the vast majority of covered
units have significantly outperformed the standard, with a small number
of units lagging behind and emitting significantly higher levels of
these HAP in communities surrounding those units. The EPA deems it
appropriate to require these lagging units to bring their pollutant
control performance up to that of their peers. Moreover, the EPA
concludes that requiring use of PM CEMS for compliance yields manifold
benefits, including increased emissions transparency and data
availability for owners and operators and for nearby communities.
The EPA's conclusions with regard to the fPM standard and
requirement to use PM CEMS for compliance demonstration are closely
related, both in terms of CAA section 112(d)(6)'s direction for the EPA
to reduce HAP emissions based on developments in practices, processes,
and control technologies, and in terms of technical compatibility.\42\
The EPA finds that the manifold benefits of PM CEMS render it
appropriate to promulgate an updated fPM emission standard as a
surrogate for non-Hg HAP metals for which PM CEMS can be used to
monitor
[[Page 38530]]
compliance. However, as the fPM limit is lowered, operators may
encounter difficulties establishing and maintaining existing
correlations for the PM CEMS and may therefore be unable to provide
accurate values necessary for compliance. The EPA has determined, based
on comments and on the additional analysis described below, that the
lowest possible fPM limit considering these challenges at this time is
0.010 lb/MMBtu with adjusted QA criteria. Therefore, the EPA determined
that this two-pronged approach--requiring PM CEMS in addition to a
lower fPM limit--is the most stringent option that balances the
benefits of using PM CEMS with the emission reductions associated with
the tightened fPM emission standard. Further, the EPA finds that the
more stringent limit of 0.006 lb/MMBtu fPM cannot be adequately
monitored with PM CEMS at this time, because the random error component
of measurement uncertainty from correlation stack testing is too large
and the QA criteria passing rate for PM CEMS is too small to provide
accurate (and therefore enforceable) compliance values. Below, we
further describe our rationale for each change.
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\42\ As noted in section III.A. above, there are nonetheless
independent reasons for adopting both the revision to the fPM
standard and the PM CEMS compliance demonstration requirement and
each of these changes would continue to be workable without the
other in effect, such that the EPA finds the two revisions are
severable from each other.
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1. Rationale for the Final Filterable PM Emission Standard
In the 2023 Proposal, the Agency proposed a lower fPM emission
standard for coal-fired EGUs as a surrogate for non-Hg HAP metals based
on developments in practices, processes, and control technologies
pursuant to CAA section 112(d)(6), including the EPA's assessment of
the differing performance of sources within the category and updated
information about the cost of controls. As described in the 2023
Proposal, non-Hg HAP metals are predominately a component of fPM, and
control of fPM results in reduction of non-Hg HAP metals (with the
exception of Se, which may be present in the filterable fraction or in
the condensable fraction as the acid gas, SeO<INF>2</INF>).
In conducting this technology review, the EPA found important
developments that informed its proposal. First, from reviewing
historical information contained in WebFIRE,\43\ the EPA observed that
most EGUs were reporting fPM emission rates well below the 0.030 lb/
MMBtu standard. The fleet was achieving these performance levels at
lower costs than estimated during promulgation of the 2012 MATS Final
Rule. Second, there are technical developments and improvements in PM
control technology since the 2012 MATS Final Rule that informed the
2023 Proposal.\44\ For example, while ESP technology has not undergone
fundamental changes since 2011, industry has learned and adopted ``best
practices'' associated with monitoring ESP operation more carefully
since the 2012 MATS Final Rule. For FFs, more durable materials have
been developed since the 2012 MATS Final Rule, which are less likely to
fail due to chemical, thermal, or abrasion failure and create risks of
high PM emissions. For instance, fiberglass (once the most widely used
material) has largely been replaced by more reliable and easier to
clean materials, which are more costly. Coated fabrics, such as Teflon
or P84 felt, also clean easier than other fabrics, which can result in
less frequent cleaning, reducing the wear that could damage filter bags
and reduce the effectiveness of PM capture.
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\43\ WebFIRE includes data submitted to the EPA from the
Electronic Reporting Tool (ERT) and is searchable at <a href="https://cfpub.epa.gov/webfire/reports/esearch.cfm">https://cfpub.epa.gov/webfire/reports/esearch.cfm</a>.
\44\ Analysis of PM and Hg Emissions and Controls from Coal-
Fired Power Plants. Andover Technology Partners. August 19, 2021.
Document ID No. EPA-HQ-OAR-2018-0794-4583.
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To examine potential revisions, the EPA evaluated fPM compliance
data for the coal-fired fleet and evaluated the control efficiency and
costs of PM controls to achieve a lower fPM standard. Based on comments
received on the 2023 Proposal, the EPA reviewed additional fPM
compliance data for 62 EGUs at 33 facilities (see 2024 Technical Memo
and attachments for detailed information). The review of additional fPM
compliance data showed that more EGUs had previously demonstrated an
ability to meet a lower fPM rate, as shown in figure 4 of the 2024
Technical Memo. Compared to the 2023 Proposal where 91 percent of
existing capacity demonstrated an ability to meet 0.010 lb/MMBtu, the
updated analysis showed that 93 percent are demonstrating the ability
to meet 0.010 lb/MMBtu with existing controls. The EPA received
comments on the cost assumptions for upgrading PM controls and found
that the costs estimated at proposal were not only too high, but that
the cost effectiveness of PM upgrades was also underestimated (i.e.,
the standard is more cost-effective than the EPA believed at proposal).
The EPA is finalizing the fPM emission limit of 0.010 lb/MMBtu with
adjusted QA criteria, based on developments since 2012, for the reasons
described in this final rule and in the 2023 Proposal as the lowest
achievable fPM limit that allows for the use of PM CEMS for compliance
demonstration purposes. First, this level of control ensures that the
highest emitters bring their performance to a level where the vast
majority of the fleet is already performing. For example, as described
above, the majority of the existing coal-fired fleet subject to this
final rule has previously demonstrated an ability to comply with the
lower 0.010 lb/MMBtu fPM limit at least 99 percent of the time during
one quarter, in addition to meeting the lower fPM limit on average
across all quarters assessed. The Agency estimates that only 33 EGUs
are currently operating above this revised limit. Compared to some of
the best performing EGUs, the 33 EGUs requiring additional PM control
upgrades or maintenance are more likely to have an ESP instead of a FF
and to demonstrate compliance using intermittent stack testing. In
addition, most of these EGUs have operated at a higher level of
utilization than the coal-fired fleet on average.
Second, as discussed in section II.A.2. above, Congress updated CAA
section 112 in the 1990 Clean Air Act Amendments to achieve significant
reductions in HAP emissions, which it recognized are particularly
harmful pollutants, and implemented a regime under which Congress
directed the EPA to make swift and substantial reductions to HAP based
upon the most stringent standards technology could achieve. This is
evidenced by Congress's charge to the EPA to ``require the maximum
degree of reduction in emissions of hazardous air pollutants (including
a prohibition on such emissions),'' that is achievable accounting for
``the cost of achieving such emission reduction, and any non-air
quality health and environmental impacts and energy requirements. . .
.'' CAA section 112(d)(2). Further, by creating separate and distinct
requirements for the EPA to consider updates to CAA section 112
pursuant to both technology review under CAA section 112(d)(6) and
residual risk review under CAA section 112(f)(2), Congress anticipated
that the EPA would strengthen standards pursuant to technology reviews
``as necessary (taking into account developments in practices,
processes, and control technologies),'' CAA section 112(d)(6), even
after the EPA concluded there was an ample margin of safety based on
the risks that the EPA can quantify.\45\ As the EPA explained in the
[[Page 38531]]
proposal, the EPA does consider costs, technical feasibility, and other
factors when evaluating whether it is necessary to revise existing
emission standards under CAA section 112(d)(6) to ensure the standards
``require the maximum degree of emissions reductions . . .
achievable.'' CAA section 112(d)(2). The text, structure, and history
of this provision demonstrate Congress's direction to the EPA to
require reduction in HAP where technology is available to do so and the
EPA accounts for the other statutory factors.
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\45\ EPA's CAA section 112(f)(2) quantitative risk assessments
evaluate cancer risk associated with a lifetime of exposure to HAP
emissions from each source in the source category, the potential for
HAP exposure to cause adverse chronic (or long-term) noncancer
health effects, and the potential for HAP exposure to cause adverse
acute (or short-term) noncancer health effects.
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Accordingly, the EPA finds that bringing this small number of units
to the performance levels of the rest of the fleet serves Congress's
mandate to the EPA in CAA section 112(d)(6) to continually consider
developments ``that create opportunities to do even better.'' See LEAN,
955 F.3d at 1093. As such, the EPA has a number of times in the past
updated its MACT standards to reflect developments where the majority
of sources were already outperforming the original MACT standards.\46\
Indeed, this final rule is consistent with the EPA's authority pursuant
to CAA section 112(d)(6) to take developments in practices, processes,
and control technologies into account to determine if more stringent
standards are achievable than those initially set by the EPA in
establishing MACT floors, based on developments that occurred in the
interim. See LEAN v. EPA, 955 F.3d 1088, 1097-98 (D.C. Cir. 2020). The
technological standard approach of CAA section 112 is based on the
premise that, to the extent there are controls available to reduce HAP
emissions, and those controls are of reasonable cost, sources should be
required to use them.
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\46\ See, e.g., National Emission Standards for Hazardous Air
Pollutants: Site Remediation Residual Risk and Technology Review, 85
FR 41680, 41698 (July 10, 2020) (proposed 84 FR 46138, 46161;
September 3, 2019)) (requiring compliance with more stringent
equipment leak definitions under a technology review, which were
widely adopted by industry); National Emissions Standards for
Mineral Wool Production and Fiberglass Manufacturing, 80 FR 45280,
45307 (July 29, 2015) (adopting more stringent limits for glass-
melting furnaces under a technology review where the EPA found that
``all glass-melting furnaces were achieving emission reductions that
were well below the existing MACT standards regardless of the
control technology in use''); National Emissions Standards for
Hazardous Air Pollutants From Secondary Lead Smelting, 77 FR 556,
564 (January 5, 2012) (adopting more stringent stack lead emission
limit under a technology review ``based on emissions data collected
from industry, which indicated that well-performing baghouses
currently used by much of the industry are capable of achieving
outlet lead concentrations significantly lower than the [current]
limit.'').
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The fleet has been able to ``over comply'' with the existing fPM
standard due to the very high PM control effectiveness of well-
performing ESPs and FFs, often exceeding 99.9 percent. But the
performance of a minority of units lags well behind the vast majority
of the fleet. As indicated by the two highest fPM rates,\47\ EGUs
without the most effective PM controls have not been able to
demonstrate fPM rates comparable to the rest of the fleet.
Specifically, the Colstrip facility, a 1,500 MW subbituminous-fired
power plant located in Colstrip, Montana, operates the only two coal-
fired EGUs in the country without the most modern PM controls (i.e.,
ESP or FF). Instead, this facility utilizes venturi wet scrubbers as
its primary PM control technology and has struggled to meet the
original 0.030 lb/MMBtu fPM limit, even while employing emissions
averaging across the operating EGUs at the facility. Colstrip is also
the only facility where the EPA estimates the current controls would be
unable to meet a lower fPM limit. Specifically, the 2018 second quarter
compliance stack tests showed average fPM emission rates above the
0.030 lb/MMBtu fPM limit, in violation of its Air Permit. Talen Energy,
one of the owners of the facility, agreed to pay $450,000 to settle
these air quality violations.\48\ As a result, the plant was offline
for approximately 2.5 months while the plant's operator worked to
correct the problem. Comments from Colstrip's majority owners discuss
the efforts this facility has undergone to improve their wet PM
scrubbers, which they state remove 99.7 percent of the fly ash
particulate but agree with the EPA that additional controls would be
needed to meet a 0.010 lb/MMBtu limit. However, as stated in
NorthWestern Energy's Annual PCCAM Filing and Application of Tariff
Changes,\49\ ``Colstrip has a history of operating very close to the
upper end limit: for 43 percent of the 651 days of compliance preceding
the forced outage its [Weighted Average Emission Rate or] WAER was
within 0.03 lb/dekatherm \50\ of the limit [. . . to comply with the
Air Permit and MATS, Colstrip's WAER must be equal to or less than 0.03
lb/dekatherm].''
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\47\ See figure 4 of the 2024 Technical Memo.
\48\ See Document CLT-1T Testimony, CLT-11, and CL-12 in Docket
190882 at <a href="https://www.utc.wa.gov/documents-and-proceedings/dockets">https://www.utc.wa.gov/documents-and-proceedings/dockets</a>.
\49\ See NorthWestern Energy's Annual PCCAM Filing and
Application for Approval of Tariff Changes, Docket No. 2019.09.058,
Final Order 7708f paragraph 21 (November 18, 2020) (noting that
``Colstrip has a history of operating very close to the upper end
limit''), available at <a href="https://reddi.mt.gov/prweb">https://reddi.mt.gov/prweb</a>.
\50\ For reference, a dekatherm is equivalent to one million
Btus (MMBtu).
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The Northern Cheyenne Reservation is 20 miles from the Colstrip
facility and the Tribe exercised its authority in 1977 to require
additional air pollution controls on the new Colstrip units (Colstrip 3
and 4, the same EGUs still operating today), recognizing the area as a
Class I airshed under the CAA. According to comments submitted by the
Northern Cheyenne Tribe, their tribal members--both those living on the
Reservation and those living in the nearby community of Colstrip--have
been disproportionally impacted by exposure to HAP emissions from the
Colstrip facility.\51\
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\51\ See Document ID No. EPA-HQ-OAR-2018-5984 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
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The EPA believes a fPM emission limit of 0.010 lb/MMBtu
appropriately takes into consideration the costs of controls. The EPA
evaluated the costs to improve current PM control systems and the cost
to install better performing PM controls (i.e., a new FF) to achieve a
more stringent emission limit. Costs of PM upgrades are much lower than
the EPA estimated in 2012, and the Agency revised its costs assumptions
as described in the 2024 Technical Memo, available in the docket. Table
4 of this document summarizes the updated cost effectiveness of the
three fPM emission limits considered in the 2023 Proposal for the
existing coal-fired fleet. For the purpose of estimating cost
effectiveness, the analysis presented in this table, described in
detail in the 2023 and 2024 Technical Memos, is based on the observed
emission rates of all existing coal-fired EGUs except for those that
have announced plans to retire by the end of 2028. The analysis
presented in table 4 estimated the costs associated for each unit to
upgrade their existing PM controls to meet a lower fPM standard. In the
cases where existing PM controls would not achieve the necessary
reductions, unit-specific FF install costs were estimated. Unlike the
cost and benefit projections presented in the RIA, the estimates in
this table do not account for any future changes in the composition of
the operational coal-fired EGU fleet that are likely to occur by 2028
as a result of other factors affecting the power sector, such as the
IRA, future regulatory actions, or changes in economic conditions. For
example, of the more than 14 GW of coal-fired capacity that the EPA
estimates would require control improvements to achieve the final fPM
rate, less than 12 GW is projected to be
[[Page 38532]]
operational in 2028 (see section 3 of the RIA for this final rule).
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The EPA has updated its costs analyses for this final rule based on
comments received and additional data review, which is described in
more detail in the 2024 Technical Memo available in the docket. In
response to commenters stating that the use of the lowest quarter's
99th percentile, or the lowest achievable fPM rate, is not indicative
of overall EGU operation and emission performance, the EPA added a
review of average fPM rates. In these updated analyses, both the lowest
quarter's 99th percentile and the average fPM rate must be below the
potential fPM limit for the EPA to assume no additional upgrades are
needed to meet a revised limit. If an EGU has previously demonstrated
an ability to meet a potential lower fPM limit, but the average fPM
rate is greater than the potential limit, the analysis for the final
rule has been updated to assume increased bag replacement frequency
(for units with FFs) or operation and maintenance costing $100,000/year
(2022$). This additional cost represents increased vigilance in
maintaining ESP performance and includes technician labor to monitor
performance of the ESP and to periodically make typical repairs (e.g.,
replacement of failed insulators, damaged electrodes or other internals
that may fail, repairing leaks in the ESP casing, ductwork, or
expansion joints, and periodic testing of ESP flow balance and any
needed adjustments).
Additionally, the Agency received comments that the PM upgrade
costs estimated at proposal were too high on a dollar per ton basis and
these costs have been updated and are provided in the 2024 Technical
Memo. Specifically, commenters demonstrated that the observed percent
reductions in fPM attributable to ESP upgrades were significantly
greater than the percent reductions that the EPA had assumed for the
proposed rule. Additionally, commenters demonstrated that ESP
performance guarantees for coal-fired utility boilers were much lower
than the EPA was aware of at proposal. These updates, as well as
improving our methodology which increases the number of EGUs estimated
to need PM upgrades, slightly lower the dollar per ton estimates from
what was presented in the 2023 Proposal.
The EPA considers costs in various ways, depending on the rule and
affected sector. For example, the EPA has considered, in previous CAA
section 112 rulemakings, cost effectiveness, the total capital costs of
proposed measures, annual costs, and costs compared to total revenues
(e.g., cost to revenue ratios).\52\ As much of the
[[Page 38533]]
fleet is already reporting fPM emission rates below 0.010 lb/MMBtu,
both the total costs and non-Hg HAP metal reductions of the revised
limit are modest in context of total PM upgrade control costs and
emissions of the coal fleet. The cost-effectiveness estimate for EGUs
reporting average fPM rates above the final fPM emission limit of 0.010
lb/MMBtu is $10,500,000/ton of non-Hg HAP metals, slightly lower than
the range presented in the 2023 Proposal.
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\52\ See, e.g., National Emission Standards for Hazardous Air
Pollutants: Mercury Cell Chlor-Alkali Plants Residual Risk and
Technology Review, 87 FR 27002, 27008 (May 6, 2022) (considered
annual costs and average capital costs per facility in technology
review and beyond-the-floor analysis); National Emission Standards
for Hazardous Air Pollutants: Primary Copper Smelting Residual Risk
and Technology Review and Primary Copper Smelting Area Source
Technology Review, 87 FR 1616, 1635 (proposed January 11, 2022)
(considered total annual costs and capital costs, annual costs, and
costs compared to total revenues in proposed beyond-the-floor
analysis); Phosphoric Acid Manufacturing and Phosphate Fertilizer
Production RTR and Standards of Performance for Phosphate
Processing, 80 FR 50386, 50398 (August 19, 2015) (considered total
annual costs and capital costs compliance costs and annualized costs
for technology review and beyond the floor analysis); National
Emissions Standards for Hazardous Air Pollutants: Ferroalloys
Production, 80 FR 37366, 37381 (June 30, 2015) (considered total
annual costs and capital costs, annual costs, and costs compared to
total revenues in technology review); National Emission Standards
for Hazardous Air Pollutants: Off-Site Waste and Recovery
Operations, 80 FR 14248, 14254 (March 18, 2015) (considered total
annual costs and capital costs, and average annual costs and capital
costs and annualized costs per facility in technology review);
National Emission Standards for Hazardous Air Pollutant Emissions:
Hard and Decorative Chromium Electroplating and Chromium Anodizing
Tanks; and Steel Pickling-HCl Process Facilities and Hydrochloric
Acid Regeneration Plants, 77 FR 58220, 58226 (September 19, 2012)
(considered total annual costs and capital costs in technology
review); Oil and Natural Gas Sector: New Source Performance
Standards and National Emission Standards for Hazardous Air
Pollutants Reviews, 77 FR 49490, 49523 (August 16, 2012) (considered
total capital costs and annualized costs and capital costs in
technology review). C.f. NRDC v. EPA, 749 F.3d 1055, 1060 (D.C. Cir.
2014).
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Further, the EPA finds that costs for facilities to meet the
revised fPM emission limit represent a small fraction of typical
capital and total expenditures for the power sector. In the 2022
Proposal (reaffirming the appropriate and necessary finding), the EPA
evaluated the compliance costs that were projected in the 2012 MATS
Final Rule relative to the typical annual revenues, capital
expenditures, and total (capital and production) expenditures.\53\ 87
FR 7648-7659 (February 9, 2022); 80 FR 37381 (June 30, 2015). Using
electricity sales data from the U.S. Energy Information Administration
(EIA), the EPA updated the analysis presented in the 2022 Proposal. We
find revenues from retail electricity sales increased from $333.5
billion in 2000 to a peak of $429.6 billion in 2008 (an increase of
about 29 percent during this period) and slowly declined since to a
post-2011 low of $388.6 billion in 2020 (a decrease of about 10 percent
from its peak during this period) in 2019 dollars.\54\ Revenues
increased in 2022 to nearly the same amount as the 2008 peak ($427.8
billion). The annual control cost estimate for the final fPM standard
based on the cost-effectiveness analysis in table 4 (see section 1c of
the 2024 Technical Memo) of this document is a very small share of
total power sector sales (about 0.03 percent of the lowest year over
the 2000 to 2019 period). Making similar comparisons of the estimated
capital and total compliance costs to historical trends in sector-level
capital and production costs, respectively, would yield similarly small
estimates. Therefore, as in previous CAA section 112 rulemakings, the
EPA considered costs in many ways, including cost effectiveness, the
total capital costs of proposed measures, annual costs, and costs
compared to total revenues to determine the appropriateness of the
revised fPM standard under the CAA section 112(d)(6) technology review,
and determined the costs are reasonable.
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\53\ See Cost TSD for 2022 Proposal at Document ID No. EPA-HQ-
OAR-2018-0794-4620 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
\54\ 2019 dollars were used for consistency with the 2023
Proposal.
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In this final rule, the EPA finds that costs of the final fPM
standard are reasonable, and that the revised fPM standard
appropriately balances the EPA's obligation under CAA section 112 to
achieve the maximum degree of emission reductions considering statutory
factors, including costs. Further, the EPA finds that its consideration
of costs is consistent with D.C. Circuit precedent, which has found
that CAA section 112(d)(2) expressly authorizes cost consideration in
other aspects of the standard-setting process, such as CAA section
112(d)(6), see Association of Battery Recyclers, Inc. v. EPA, 716 F.3d
667, 673-74 (D.C. Cir. 2013), and that CAA section 112 does not mandate
a specific method of cost analysis in an analogous situation when
considering the beyond-the-floor review. See NACWA v. EPA, 734 F.3d
1115, 1157 (D.C. Cir. 2013) (finding the statute did not ``mandate a
specific method of cost analysis''); see also NRDC v. EPA, 749 F.3d
1055, 1060-61 (D.C. Cir. 2014).
As discussed in section IV.C.1. in response to comments regarding
the relatively higher dollar per ton cost effectiveness of the final
fPM standard, the EPA finds that in the context of this industry and
this rulemaking, the updated standards are an appropriate exercise of
the EPA's standard setting authority pursuant to the CAA section
112(d)(6) technology review. As commenters rightly note, the EPA
routinely considers the cost effectiveness of potential standards where
it can consider costs under CAA section 112, e.g., in conducting
beyond-the-floor analyses and technology reviews, to determine the
achievability of a potential control option. And the D.C. Circuit
recognized that the EPA's interpretation of costs as ``allowing
consideration of cost effectiveness was reasonable.'' NRDC v. EPA, 749
F.3d 1055, 1060-61 (D.C. Cir. 2014) (discussing the EPA's consideration
of cost effectiveness pursuant to a CAA section 112(d)(2) beyond-the-
floor analysis). However, cost effectiveness is not the sole factor
that the EPA considers when determining the achievability of a
potential standard in conducting a technology review, nor is cost
effectiveness the only value that the EPA considers with respect to
costs.\55\ Some commenters pointed to other rulemakings (which are
discussed in section IV.C.1. above) where the EPA determined not to
pursue potential control options with relatively higher cost-
effectiveness estimates as compared to prior CAA section 112
rulemakings. However, there were other factors that the EPA considered,
in addition to cost effectiveness, that counseled against pursuing such
updates. In this rulemaking, the EPA finds that several factors
discussed throughout this record make promulgation of the new fPM
standard appropriate under CAA section 112(d)(6). First, a wide
majority of units have invested in the most-effective PM controls and
are already demonstrating compliance with the new fPM standard and at
lower costs than assumed during promulgation of the original MATS fPM
emission limit. Of the 33 EGUs that the EPA estimated would require
control improvements to meet a 0.010 lb/MMBtu fPM standard, only two
are not using the most effective PM control technologies available. The
EPA assumed that these two units would need to install FFs to achieve
the 0.010 lb/MMBtu emission standard, and the cost of those FF
retrofits accounts for 42 percent of the total annualized costs
presented in table 4. Further, 11 EGUs that the EPA assumed would
require different levels of ESP upgrades to meet the 0.010 lb/MMBtu
emission standard (all of which have announced retirement dates between
2031 and 2042 resulting in shorter assumed amortization periods)
account for about 57 percent of the total annualized costs. The
remaining 1 percent of the total annualized costs are associated with
10 EGUs with existing FFs that the EPA
[[Page 38534]]
assumes will require bag upgrades or increased bag changeouts and 10
EGUs that are assumed to need additional operation and maintenance of
existing ESPs, which is further explained in the 2024 Technical Memo.
Since only a small handful of units emit significantly more than peer
facilities, the Agency finds these upgrades appropriate. Additionally,
the size and unique nature of the coal-fired power sector, and the
emission reductions that will be achieved by the new standard, in
addition to the costs, make promulgation of the new standard
appropriate under CAA section 112(d)(6).
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\55\ See note 50, above, for examples of other costs metrics the
EPA has considered in prior CAA section 112 rulemakings.
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The power sector also operates differently than other industries
regulated under CAA section 112.\56\ For example, the power sector is
publicly regulated, with long-term decision-making and reliability
considerations made available to the public; it is a data-rich sector,
which generally allows the EPA access to better information to inform
its regulation; and the sector is in the midst of an energy generation
transition leading to plant retirements that are independent of EPA
regulation. Because of the relative size of the power sector, while
cost effectiveness of the final standard is relatively high as compared
to prior CAA section 112 rulemakings involving other industries, costs
represent a much smaller fraction of industry revenue. In the likely
case that the power sector's transition to lower-emitting generation is
accelerated by the IRA, for example, the total costs and emission
reductions achieved by each final fPM standard in table 4 of this
document would also be an overestimate.
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\56\ This is a fact which Congress recognized in requiring the
EPA to first determine whether regulation of coal-fired EGUs was
``appropriate and necessary'' under CAA section 112(n)(1)(A) before
proceeding to regulate such facilities under CAA section 112's
regulatory scheme.
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As demonstrated in the proposal, the power sector, as a whole, is
achieving fPM emission rates that are well below the 0.030 lb/MMBtu
standard from the 2012 Final MATS Rule, with the exception of a few
outlier facilities. The EPA estimates that only one facility (out of
the 151 evaluated coal-fired facilities), which does not have the most
modern PM pollution controls and has been unable to demonstrate an
ability to meet a lower fPM limit, will be required to install the
most-costly upgrade to meet the revised standards, which significantly
drives up the cost of this final rule. However, the higher costs for
one facility to install demonstrated improvements to its control
technology should not prevent the EPA from establishing achievable
standards for the sector under the EPA's CAA section 112(d)(6)
authority. Instead, the EPA finds that it is consistent with its CAA
section 112(d)(6) authority to consider the performance of the industry
at large. The average fPM emissions of the industry demonstrate the
technical feasibility of higher emitting facilities to meet the new
standard and shows there are proven technologies that if installed at
these units will allow them to significantly lower fPM and non-Hg HAP
metals emissions.
In this rulemaking, the EPA also determined not to finalize a more
stringent standard for fPM emissions, such as a limit of 0.006 lb/MMBtu
or lower, which the EPA took comment on in the 2023 Proposal. The EPA
declines to finalize an emission standard of 0.006 lb/MMBtu or lower
primarily due to technical limitations in using PM CEMS for compliance
demonstration purposes described in the next section. The EPA has
determined that a fPM emission standard of 0.010 lb/MMBtu is the lowest
that would also allow the use of PM CEMS for compliance demonstration.
Additionally, the EPA also considered the overall higher costs
associated with a more stringent standard as compared to the final
standard, which the EPA considered under the technology review.
Additionally, compliance with a fPM emission limit of 0.006 lb/
MMBtu could only be demonstrated using periodic stack testing that
would require test run durations longer than 4 hours \57\ and would not
provide the source, the public, and regulatory authorities with
continuous, transparent data for all periods of operation. Establishing
a fPM limit of 0.006 lb/MMBtu while maintaining the current compliance
demonstration flexibilities of quarterly ``snapshot'' stack testing
would, theoretically, result in greater emission reductions; however,
the measured emission rates are only representative of rates achieved
at optimized conditions at full load. While coal-fired EGUs have
historically provided baseload generation, they are being dispatched
much more as load following generating sources due to the shift to more
available and cheaper natural gas and renewable generation. As such,
traditional generation assets--such as coal-fired EGUs--will likely
continue to have more startup and shutdown periods, more periods of
transient operation as load following units, and increased operation at
minimum levels, all of which can produce higher PM emission rates.
Maintaining the status quo with quarterly stack testing will likely
mischaracterize emissions during these changing operating conditions.
Thus, while a fPM emission limit of 0.006 lb/MMBtu paired with use of
quarterly stack testing may appear to be more stringent than the 0.010
lb/MMBtu standard paired with use of PM CEMS that the EPA is finalizing
in this rule, there is no way to confirm emission reductions during
periods in between quarterly tests when emission rates may be higher.
Therefore, the Agency is finalizing a fPM limit of 0.010 lb/MMBtu with
the use of PM CEMS as the only means of compliance demonstration. The
EPA has determined that this combination of fPM limit and compliance
demonstration represents the most stringent available option taking
into account the statutory considerations.
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\57\ Run durations greater than 4 hours would ensure adequate
sample collection and lower random error contributions to
measurement uncertainty for a limit of 0.006 lb/MMBtu. The EPA aims
to keep run durations as short as possible, generally at least one
but no more than 4 hours in length, in order to minimize impacts to
the facility (e.g., overall testing campaign testing costs, employee
focused attention and safety).
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The EPA also determined not to finalize a fPM standard of 0.015 lb/
MMBtu, which the EPA took comment on in the 2023 Proposal, because the
EPA determined that a standard of 0.010 lb/MMBtu is appropriate for the
reasons discussed above.
In this rule, the EPA is also reaching a different conclusion from
the 2020 Technology Review with respect to the fPM emission standard
and requirements to utilize PM CEMS. As discussed in section II.D.
above, the 2020 Technology Review did not consider developments in the
cost and effectiveness of proven technologies to control fPM as a
surrogate for non-Hg HAP metals emissions, nor did the EPA evaluate the
current performance of emission reduction control equipment and
strategies at existing MATS-affected EGUs. In this rulemaking, in which
the EPA reviewed the findings of the 2020 Technology Review, the Agency
determined there are important developments regarding the emissions
performance of the coal-fired EGU fleet, and the costs of achieving
that performance that are appropriate for the EPA to consider under its
CAA section 112(d)(6) authority, and which are the basis for the
revised emissions standards the EPA is promulgating through this final
rule.
The 2012 MATS Final Rule contains emission limits for both
individual and total non-Hg HAP metals (e.g., lead, arsenic, chromium,
nickel, and cadmium), as well as emission limits for fPM. Those non-Hg
HAP metals
[[Page 38535]]
emission limits serve as alternative emission limits because fPM was
found to be a surrogate for either individual or total non-Hg HAP
metals emissions. While EGU owners or operators may choose to
demonstrate compliance with either the individual or total non-Hg HAP
metals emission limits, the EPA is aware of just one owner or operator
who has provided non-Hg HAP metals data--both individual and total--
along with fPM data, for compliance demonstration purposes. This is for
a coal refuse-fired EGU with a generating capacity of 46.1 MW. Given
that owners or operators of all the other EGUs that are subject to the
requirements in MATS have chosen to demonstrate compliance with only
the fPM emission limit, the EPA proposed to remove the total and
individual non-Hg HAP metals emission limits from all existing MATS-
affected EGUs and solicited comment on our proposal. In the
alternative, the EPA took comment on whether to retain total and/or
individual non-Hg HAP metals emission limits that have been lowered
proportionally to the revised fPM limit (i.e., revised lower by two-
thirds to be consistent with the revision of the fPM standard from
0.030 lb/MMBtu to 0.010 lb/MMBtu).
Commenters urged the EPA to retain the non-Hg HAP metals limits,
arguing it is incongruous for the EPA to eliminate the measure for the
pollutants that are the subject of regulation under CAA section
112(d)(6), notwithstanding the fact that the fPM limit serves as a more
easily measurable surrogate for these HAP metals. Additionally, some
commenters stated that the inability to monitor HAP metals directly
will significantly impair the EPA's ability to revise emission
standards in the future.
After considering comments, the EPA determined to promulgate
revised total and individual non-Hg HAP metals emission limits for
coal-fired EGUs that are lowered proportionally to the revised fPM
standard. Just as this rule requires owners or operators to demonstrate
continuous compliance with fPM limits, owners or operators who choose
to demonstrate compliance with these alternative limits will need to
utilize approaches that can measure non-Hg HAP metals on a continuous
basis--meaning that intermittent emissions testing using Reference
Method 29 will not be a suitable approach. Owners or operators may
petition the Administrator to utilize an alternative test method that
relies on continuous monitoring (e.g., multi-metal CMS) under the
provisions of 40 CFR 63.7(f). The EPA disagrees with the suggestion
that failure to monitor HAP metals directly could impair the ability to
revise those standards in the future.
2. Rationale for the Final Compliance Demonstration Options
In the 2023 Proposal, the EPA proposed to require that coal- and
oil-fired EGUs utilize PM CEMS to demonstrate compliance with the fPM
standard used as a surrogate for non-Hg HAP metals. The EPA proposed
the requirement for PM CEMS based on its assessment of costs of PM CEMS
versus stack testing, and the many other benefits of using PM CEMS
including increased transparency and accelerated identification of
anomalous emissions. In particular, the EPA noted the ability for PM
CEMS to provide continuous feedback on control device and plant
operations and to provide EGU owners and operators, regulatory
authorities, and members of nearby communities with continuous
assurance of compliance with emissions limits as an important benefit.
Further, the EPA explained in the 2023 Proposal that PM CEMS are
currently in use by approximately one-third of the coal-fired fleet,
and that PM CEMS can provide low-level measurements of fPM from
existing EGUs.
After considering comments and conducting further analysis,\58\ the
EPA is finalizing the use of PM CEMS for compliance demonstration
purposes for coal- and oil-fired EGUs pursuant to its CAA section
112(d)(6) authority. As discussed in section IV.D.1. above, Congress
intended for CAA section 112 to achieve significant reductions in HAP,
which it recognized as particularly harmful pollutants. The EPA finds
that the benefits of PM CEMS to provide real-time information to owners
and operators (who can promptly address any problems with emissions
control equipment), to regulators, to adjacent communities, and to the
general public, further Congress's goal to ensure that emission
reductions are consistently maintained. The EPA determined not to
require PM CEMS for existing IGCC EGUs, described in section VI.D., due
to technical issues calibrating CEMS on these types of EGUs due to the
difficulty in preparing a correlation range because these EGUs are
unable to de-tune their fPM controls and their existing emissions are
less than one-tenth of the final emission limit. Further, the EPA finds
additional authority to require the use of PM CEMS under CAA section
114(a)(1)(C), which allows that the EPA may require a facility that
``may have information necessary for the purposes set forth in this
subsection, or who is subject to any requirement of this chapter'' to
``install, use, and maintain such monitoring equipment'' on a ``on a
one-time, periodic or continuous basis.'' 114(a)(1)(C).
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\58\ The EPA explains additional analyses of PM CEMS in the
memos titled Suitability of PM CEMS Use for Compliance Determination
for Various Emissions Levels and Summary of Review of 36 PM CEMS
Performance Test Reports versus PS11 and Procedure 2 of 40 CFR part
60, appendices B and F, respectively, which are available in the
docket.
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From the EPA's review of PM CEMS, the Agency determined that a fPM
standard of 0.010 lb/MMBtu with adjusted QA criteria--used to verify
consistent correlation of CEMS data initially and over time--is the
lowest fPM emission limit possible at this time with use of PM
CEMS.\59\ PM CEMS correlated using these values will ensure accurate
measurements--either above, at, or below this emission limit. As
discussed in section IV.D.1. above, one of the reasons the EPA
determined not to finalize a more stringent standard for fPM is because
it would prove challenging to verify accurate measurement of fPM using
PM CEMS. Specifically, as mentioned in the Suitability of PM CEMS Use
for Compliance Determination for Various Emission Levels, memorandum,
available in the docket, no fPM standard more stringent than 0.010 lb/
MMBtu with adjusted QA criteria is expected to have acceptable passing
rates for the QA checks or acceptable random error for reference method
testing.
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\59\ The EPA notes that the fPM standard [0.010 lb/MMBtu] is
based on hourly averages obt
[…truncated; see source link]Indexed from Federal Register on May 7, 2024.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.