[Federal Register Volume 89, Number 84 (Tuesday, April 30, 2024)]
[Rules and Regulations]
[Pages 34137-34144]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-08713]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R01-OAR-2023-0188; FRL-11025-03-R1]


Air Plan Approval; New Hampshire; Reasonable Available Control 
Technology for the 2008 and 2015 Ozone Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is approving State 
Implementation Plan (SIP) revisions submitted by the State of New 
Hampshire. The revisions establish NOX reasonably available 
control technology (RACT) requirements for coal-fired cyclone boilers 
located in the state, portions of New Hampshire's NOX RACT 
certifications for the 2008 and 2015 ozone standards that pertain to 
requirements for coal-fired cyclone boilers, and withdrawal from the 
SIP of two previously issued RACT orders. This action is being taken in 
accordance with the Clean Air Act (CAA).

DATES: This rule is effective on May 30, 2024.

ADDRESSES: EPA has established a docket for this action under Docket 
Identification No. EPA-R01-OAR-2023-0188. All documents in the docket 
are listed on the https://www.regulations.gov website. Although listed 
in the index, some information is not publicly available, i.e., CBI 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 at https://www.regulations.gov or at the U.S. Environmental Protection Agency, EPA 
Region 1 Regional Office, Air and Radiation Division, 5 Post Office 
Square--Suite 100, Boston, MA. EPA requests that if at all possible, 
you contact the contact listed in the FOR FURTHER INFORMATION CONTACT 
section to schedule your inspection. The Regional Office's official 
hours of business are Monday through Friday, 8:30 a.m. to 4:30 p.m., 
excluding legal holidays and facility closures due to COVID-19.

FOR FURTHER INFORMATION CONTACT: Bob McConnell, Environmental Engineer, 
Air and Radiation Division (Mail Code 5-MD), U.S. Environmental 
Protection Agency, Region 1, 5 Post Office Square, Suite 100, Boston, 
Massachusetts, 02109-3912; (617) 918-1046; [email protected].

SUPPLEMENTARY INFORMATION: 
    Throughout this document whenever ``we,'' ``us,'' or ``our'' is 
used, we mean EPA.

Table of Contents

I. Background and Purpose
II. Response to Comments
III. Final Action
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews

I. Background and Purpose

    On July 10, 2023 (88 FR 43483), EPA published a Notice of Proposed 
Rulemaking (NPRM) for the State of New Hampshire. The NPRM proposed to 
determine that the State has adopted regulations meeting the 
requirements for reasonably available control technology (RACT) for the 
2008 and 2015 ozone national ambient air quality standards (NAAQS), to 
approve amendments to a related regulation that New Hampshire revised 
as part of its RACT certifications for these two NAAQS, to approve a 
revision to the State's definition of emergency generator, and removal 
from the SIP of two previously issued RACT orders affecting coal-fired 
cyclone boilers operated by Merrimack Station located in Bow, New 
Hampshire. EPA received a comment letter from the Sierra Club dated 
August 9, 2023, that opposed New Hampshire's NOX RACT limits 
applicable to coal-fired cyclone boilers. We approved the portions of 
the proposal unaffected by this comment letter in a final rule 
published on September 6, 2023 (88 FR 60893). In this final rule, we 
are approving the remaining portions of these SIP revisions, which 
include requirements within New Hampshire's Env-A 1300 establishing 
RACT requirements for coal-fired electrical cyclone boilers, the 
portions of New Hampshire's NOX RACT certifications for the 
2008 and 2015 ozone standards that pertain to requirements for coal-
fired cyclone boilers, and we are taking final action to withdraw from 
the New Hampshire SIP two RACT orders that contain less stringent 
requirements for cyclone boilers. Please see our July 10, 2023 proposed 
rule for additional background

[[Page 34138]]

and a more detailed explanation of our proposed action.

II. Response to Comments

    As mentioned, we received one comment letter on our July 10, 2023 
proposed approval, which was from the Sierra Club and expressed 
opposition to the proposed approval of New Hampshire's (NH's) 
NOX RACT requirements applicable to the coal-fired cyclone 
boilers operated by Granite Shore Power at its Merrimack Station 
electrical generating facility located in Bow. Our responses to the 
comments raised by Sierra Club appear below.
    Comment: Sierra Club commented that the emission rate of 0.22 lbs/
MMBtu for two coal-fired cyclone boilers at Merrimack Station, herein 
referred to as units MK1 and MK2, is inadequate as RACT. Sierra Club 
commented that, since 2018, MK1 and MK2 consistently demonstrated the 
ability to meet a 24-hour average emission rate at or below 0.20 lbs/
MMBtu, which is 10% lower than NH's emissions limit of 0.22 lbs/MMBtu, 
and thereby asserted that the state's limit is too lenient.
    Response: New Hampshire developed its NOX RACT emissions 
limits for MK1 and MK2 in consideration of a number of factors. One 
such factor was the observation that the selected emissions limit of 
0.22 lbs NOX/MMBtu represented emission reductions of 83% 
and 91% from uncontrolled levels for MK1 and MK2, respectively,\1\ 
which is a high level of control. Given MK2's larger size and 
emissions, the emissions weighted average reduction from uncontrolled 
levels for both units combined is 88% based on emissions data for 2022. 
This level of control is near the upper end of the emission reduction 
capability of selective catalytic reduction (SCR) control systems as 
noted within EPA control technology explanatory materials, such as the 
agency's fact sheet on SCR NOX control technology, which 
indicates a control range of between 70-90% is achievable from such 
systems.\2\ Additionally, correspondence dated May 25, 2018 from the 
facility owner, Granite Shore Power, to the New Hampshire DES indicated 
that a more restrictive normal operating mode emission rate of 0.20 
lbs/MMBtu on a 24-hr basis that was originally considered by NH DES was 
beyond the original emission reduction control capability of the units 
when they were newly installed. Granite Shore Power reiterated this 
point in a January 17, 2020 correspondence to the New Hampshire DES 
concerning regional haze requirements in which they note that the 
revised NOX RACT limits ``represent the most effective use 
of the SCR, given that the system must be operated year round at or 
above its design capacity to demonstrate compliance.''
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    \1\ NH based its emission reduction calculations on the 
uncontrolled levels observed during stack tests for MK1 and MK2.
    \2\ Air Pollution Control Technology Fact Sheet: Selective 
Catalytic Reduction (SCR); EPA-452/F-03-032.
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    In 2018 as New Hampshire was developing its NOX RACT 
emissions limit for MK1 and MK2, the state reviewed the emissions data 
from the continuous emissions monitoring systems (CEMS) on the units 
collected in 2000, when the equipment was newly installed, through 
2007. Merrimack Station installed a second SCR control unit in 1999 due 
to the Ozone Transport Region (OTC) NOX budget program. 
Previously only one of the Merrimack Station units had SCR, installed 
circa 1995. This period of time coincides with the period of time that 
Electric Generating Units (EGUs) in New Hampshire had new emission 
control obligations under the OTC's NOX Budget program.\3\ 
This program began in 1999 and continued through 2002, at which point 
most of the EGUs transitioned to the EPA's first ozone season 
NOX control program, that being the NOX SIP 
Call.\4\ Although EGUs in New Hampshire were not required to 
participate in the EPA's NOX SIP Call program, New Hampshire 
maintained, as an anti-backsliding measure, the OTC NOX 
Budget program's ozone season cap for sources located in the state, 
including MK1 and MK2, beyond 2002. EPA facilitated oversight of New 
Hampshire's post-2002 NOX Budget program by creating a 
separate account referred to as the ``NH NOX Program'' on 
its Clean Air Markets Program Data (CAMPD) website.\5\
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    \3\ EPA approved the program New Hampshire developed to comply 
with the OTC's NOX Budget program into the NH SIP on 
November 14, 2000 (see 65 FR 68078).
    \4\ See EPA's October 27, 1998, (63 FR 57356) final rulemaking 
action known as the NOX SIP Call.
    \5\ The NOX emissions data for the New Hampshire's 
EGU's, including MK1 and MK2, are still maintained on the CAMPD 
website by retrieving data under the program name ``NH 
NOX Program''.
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    New Hampshire's selection of 0.22 lbs NOX/MMBtu, to be 
met on a 24-hour averaging time basis, is reasonable from a statistical 
perspective. The emissions limit New Hampshire chose corresponds to the 
emissions rate representative of the 95th percentile emissions rate for 
days of operation without a startup or shutdown event. In other words, 
MK1 and MK2 operated at or below an emission rate of 0.22 lbs 
NOX/MMBtu 95 percent of the time between 2000 and 2007, 
which as mentioned above coincided with the time period when the SCR 
controls were newly installed and MK1 and MK2 were subject to the 
requirements of the OTC's NOX budget program that began in 
1999.
    The data Sierra Club show in Table 2 of their comment letter are 
based on monthly averages, whereas the limits being approved herein for 
Merrimack Station are short term, 24-hour averages. Shorter term limits 
are harder to meet and require that the control system be consistently 
and effectively run. Conversely, a 30-day average can be met despite 
days on which the controls are not run effectively, or perhaps not run 
at all, as long as there are enough days of operation below the 
emission limit to average this out. If the short-term emissions limit 
NH requires for MK1 and MK2 were set at a lower rate, such as 0.20 or 
below as Sierra Club suggests, there would be many days with violations 
due to minor fluctuations in the rate of the chemical reaction that 
occurs between the catalyst system, ammonia, and oxygen, which 
accomplishes the reduction in NOX emissions in the effluent 
from the equipment. NH reviewed historic data and identified periods of 
time when the facility's controls produced low daily emissions rates. 
Importantly, during those past time periods, the facility was not 
required to meet a 24-hour emissions rate. By imposing a new, 24-hour 
emissions limit, NH had to choose an emissions rate that was feasible, 
given the normal fluctuations in the boiler and control system 
operations, that the facility could reasonably be expected to meet 
every day. Although historic data showed the facility could meet a 0.22 
rate 95% of the time, that also means that it did not meet that rate 5% 
of the time. It now will be required to meet that rate 100% of the 
time. A description of how SCR control systems operate and the various 
aspects of the induced chemical reaction that occurs to change the 
nitrogen oxides released from the combustion process to elemental 
nitrogen and water vapor is contained within the SCR Air Pollution 
Control Fact Sheet included in the docket for this final rule.
    New Hampshire also considered limits adopted by other states for 
similar equipment in making its NOX RACT determination, but 
could not find reasonable comparisons based on coal type, boiler design 
type, boiler age, and control technology. This point is discussed in 
further detail below. Lastly, we note that the SCR control systems 
operated by Merrimack Station

[[Page 34139]]

were amongst the first such units installed on coal-fired electric 
utility boilers in the U.S., with MK2's SCR being installed in 1995, 
and MK1's in 1999. Despite the age of the control equipment, the 
overall NOX control efficiency as noted above remains at a 
high level. Additionally, as explained further in the TSD accompanying 
this final action, by observing the hourly emissions rate data 
available from EPA's Clean Air Markets Program Database (CAMPD) website 
it can be clearly seen that achievement of this rate on a 24-hour 
averaging time basis requires the continuous operation of the SCR 
controls, as even one or two hours of operation without the controls 
engaged while heat input is high would jeopardize achievement of the 
short term, 0.22 lbs/MMBtu emission limit.
    Comment: Sierra Club commented that other coal-fired cyclone 
boilers are required to meet lower emissions limits and included data 
for other cyclone boilers to support its claim. Sierra Club also 
provided data on NOX emission rates at Merrimack Station and 
asserted that lower NOX emission rates are achievable and 
should be required by RACT.
    Response: EPA agrees that there are other coal-fired cyclone 
boilers that are required to meet lower emissions limits. However, 
EPA's review of the characteristics of the coal-fired cyclone boilers 
identified as such within its Clean Air Markets and National Electric 
Energy Data System (NEEDS) databases and operating since 2009 indicates 
that only two units, the now closed Dallman units 31 and 32 in 
Illinois, have technical specifications similar to the Merrimack units 
in that they were bituminous coal fired cyclone boilers whose 
NOX emissions were controlled solely by SCR. However, those 
units are not directly comparable to MK1 and MK2 for a number of 
reasons, including their smaller size, newer age of the SCR control 
equipment, and for comparison to MK2, that unit's inordinately high 
uncontrolled emission rate of 2.4 lbs. NOX/MMBtu, which is 
considerably higher than the average emission rate for bituminous coal-
fired cyclone boilers of 1.3 lbs/MMBtu as documented within Table 1.1-3 
of section 1.1 of EPA's emissions factors reference document, AP-42. 
Although we did identify several other bituminous coal-fired cyclone 
boilers within EPA databases, those boilers operated additional 
NOX control equipment not used by MK1 and MK2, most often 
overfire air (OFA) systems. The boilers located at the New Madrid and 
Thomas Hill facilities in Missouri noted by Sierra Club also operate 
OFA systems in addition to the SCR control system. Granite Shore Power 
(GSP), Merrimack Station's owner, recently evaluated the feasibility of 
retrofitting its cyclone boilers with additional NOX 
emission control equipment including an overfire air system as part of 
a technical analysis it performed at the request of the New Hampshire 
Air Resources Division (NH-ARD). The state made this request as it 
developed its SIP revision for the Regional Haze program. As New 
Hampshire notes within its May 5, 2022, Regional Haze Plan, GSP 
concludes that retrofitting MK1 and MK2 was not feasible for the 
following reason:
    ``OFA would result in reduced boiler performance, potential boiler 
modifications to boiler surface areas, increased fouling, boiler tube 
erosion, and cyclone wear. Any installation is complicated by, if not 
impossible, due to the engineering and design challenges of the windbox 
configuration and screen tubes at Merrimack. In addition, the 
installation of an OFA system after the installation of an SCR is 
likely to produce little to no improvement in NOX 
reductions. Any of these changes would also have the potential to 
negatively impact the removal capability of the FGD (flue gas 
desulfurization) \6\ and the collection capability of the ESPs 
(electrostatic precipitators \7\).'' As documented within section 4.2.9 
of its May 5, 2022, Regional Haze Plan Periodic Comprehensive Revision, 
New Hampshire reviewed and agreed with Granite Shore Power's assessment 
that NOX emissions from the coal-fired boilers at Merrimack 
Station are well controlled and subject to appropriate NOX 
emissions limits. Large boilers like these vary considerably in their 
design and operational characteristics, and so retrofits possible for 
some equipment may not be possible elsewhere.
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    \6\ FGD systems are used to reduce emissions of sulfur dioxide 
and mercury.
    \7\ ESP systems are used to reduce emissions of particulate 
matter.
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    EPA has reviewed New Hampshire's assessment of the information 
provided by GSP and agrees with the state's conclusion that requiring 
installation of new equipment at the Merrimack units, such as OFA, is 
not economically feasible for purposes of RACT. The facility is 
scheduled to permanently cease coal-fired boiler operations no later 
than June 1, 2028 as indicated by a recent agreement between Granite 
Shore Power, the EPA, the Sierra Club, and the Conservation Law 
Foundation.\8\ Leading up to this cessation in operations, there is a 
declining need for output from the facility by the region's electrical 
grid operator, ISO-New England; there has been limited or non-
acceptance of offers to produce electricity from this facility in the 
forward capacity auctions conducted by ISO-New England.\9\ Given this 
limited remaining use of these units, combined with the fact that the 
facility's current SCR NOX control systems already achieve a 
high level of control, the cost of new controls per ton of emission 
reduction achieved is not economically feasible for purposes of RACT.
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    \8\ A copy of the press releases from Conservation Law 
Foundation, Sierra Club, and Granite Shore Power announcing the 
closure agreement is included in the docket for the rule.
    \9\ The results of ISO New England's 17th Forward Capacity 
Auction, which is for the time period June 1, 2026 through May 31, 
2027, indicates that bids to offer power to the New England grid 
from MK1 and MK2 were not accepted for this time period. See: 
https://www.iso-ne.com/static-assets/documents/2023/03/fca_17_results_filing.pdf.
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    Comment: Sierra Club commented that other states require lower 
emissions limits for coal-fired power plants. In its comments, Sierra 
Club asserted that several other states, including Pennsylvania, New 
Jersey, Maryland, and Delaware, impose lower emission limits at coal-
fired power plants.
    Response: EPA agrees that other states require lower emissions 
limits for coal-fired cyclone boilers. However, as noted above, New 
Hampshire and EPA have not identified coal-fired boilers that offer an 
appropriate or equivalent comparison to the units at Merrimack Station. 
Sierra Club points to lower short-term emission limits adopted by other 
states for coal-fired boilers, such as Delaware's 0.125 lbs/MMBtu limit 
based on a 24-hour averaging time, and Maryland's 0.10 lbs/MMBtu limit 
which is also based on a 24-hour averaging time and includes all modes 
of operation. However, none of the coal-fired boilers in these states 
match the type of boiler and fuel type of Merrimack Station's boilers, 
which as mentioned are bituminous fueled cyclone boilers operating only 
SCR controls that were installed many years ago. The only coal-fired 
electric utility boiler in Delaware is located at the Indian River 
Generating Station in Dagsboro and is a dry-bottom, turbo-fired boiler. 
Regarding Maryland, the coal-fired boiler located at the AES Warrior 
Run Cogeneration facility in Cumberland is an atmospheric circulating 
fluidized bed boiler, the two coal boilers at Brandon Shores are both 
dry bottom boilers with circular wall burners, and the coal boiler at 
Wagner Station is a supercritical steam boiler. Therefore, EPA 
concludes from a technical perspective that limits deemed RACT for 
these specific units in New

[[Page 34140]]

Hampshire \10\ should be higher than limits in Delaware and Maryland.
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    \10\ RACT is defined, in part, as ``the lowest emissions 
limitation a particular source is capable of meeting by the 
application of control technology that is reasonably available 
considering technological and economic feasibility'' (44 FR 53762; 
September 17, 1979).
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    Sierra Club also points to RACT limits for coal-fired boilers 
located in Pennsylvania that EPA recently finalized with a Federal 
Implementation Plan published in the Federal Register on August 31, 
2022,\11\ as an example of more restrictive emissions limits in other 
states relative to what New Hampshire has required for the coal units 
at Merrimack Station. A number of factors differentiate the units at 
Merrimack Station compared with those located in Pennsylvania. For 
example, none of the Pennsylvania units are of the high-emitting, 
cyclone boiler configuration as both units at Merrimack Station. 
Additionally, the Merrimack Station boilers are much smaller than the 
Pennsylvania units. Most of the units addressed in the Pennsylvania 
RACT FIP are between 600 and 900 MW, whereas the Merrimack units are 
around 100 MW and 300 MW. As a result of their smaller size, the 
Merrimack units have considerably lower annual emissions. Over the past 
five years (2019 through 2023), the total annual NOX 
emissions from both Merrimack units ranges from 175 to 500 tons/year. 
As a point of comparison, the Keystone and Conemaugh facilities in 
Pennsylvania each had average annual NOX emissions over 4500 
tpy since 2019. The low annual emissions at Merrimack combined with 
their very low utilization and required stop of use in 2028 leads to 
any additional controls at Merrimack being not economically feasible 
for purposes of RACT.
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    \11\ See 87 FR 53381.
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    Comment: Sierra Club commented that recent air pollution transport 
rules such as the Revised Cross-State Air Pollution Rule Update (RCU) 
for the 2008 ozone NAAQS and the Good Neighbor Plan (GNP) for the 2015 
ozone standard contain more restrictive emission rates than what New 
Hampshire requires for NOX limits for MK1 and MK2.
    Response: The requirements within EPA's transport rules do not 
offer legitimate comparisons to the emission limits New Hampshire has 
set as RACT limits for Merrimack Station's coal-fired cyclone boilers 
for a number of reasons. First, regarding the RCU, EPA did not 
establish short term emission limits for coal-fired EGU boilers within 
that rule, but rather only imposed ozone season,\12\ mass-based 
emissions budgets. These budgets were based in part on a statistical 
analysis showing that coal-fired EGUs equipped with existing SCR are 
capable of achieving an emissions rate of 0.08 lbs/MMBtu on a fleetwide 
average and over an entire ozone season. Additionally, the RCU allows a 
facility to remain in compliance if the facility holds sufficient 
emissions allowances to cover the amount of emissions produced. See 86 
FR 23056, 23090 (April 30, 2021). New Hampshire's RACT emissions limits 
are structured much differently, requiring that the facility meet a 
NOX emissions rate of 0.22 lbs/MMBtu on a short-term, 24-
hour averaging time basis. Additionally, the historical data New 
Hampshire analyzed for these particular units indicate that this is 
near the limit of what SCR at these units is capable of achieving. As 
explained elsewhere in this notice, emissions limits with short 
averaging times are more difficult to meet because there is less time 
to offset emissions that occur while operating above the emissions 
limit with emissions produced during times of operation below the 
limit.
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    \12\ The ozone season encompasses the 153-day period from May 1 
to September 30.
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    Regarding comparisons to the NOX reductions required of 
electric utility boilers subject to the GNP, a statistical analysis 
similar to the RCU of fleetwide emissions performance over an entire 
ozone season informed the identification of emissions rates used to set 
state-level EGU budgets. Thus, similar to the RCU as mentioned above, 
these rates do not offer a good comparison to the short-term limits New 
Hampshire requires for MK1 and MK2. Although the GNP, unlike the RCU, 
adds an additional, short term, 24-hour average backstop daily rate of 
0.14 lbs NOX/MMBtu for coal-fired boilers with SCR,\13\ 
there are substantial differences in how EPA established and will 
implement that backstop rate within the trading program versus how New 
Hampshire established and implements its NOX RACT limits for 
Merrimack Station's coal-fired boilers. First, we note that the GNP's 
24-hour backstop rate will only apply to emissions during the ozone 
season that exceed by more than 50 tons a daily average NOX 
emissions rate of 0.14 lb/MMBtu. New Hampshire's limits apply year-
round and do not excuse the first 50 tons, or any amount of emissions, 
that exceed its emissions limits.\14\ Furthermore, the GNP's 24-hour 
backstop rate, if exceeded beyond the 50 ton exemption mentioned above, 
can be complied with via the surrender of emissions allowances at a 3 
for 1 surrender ratio; New Hampshire's limits do not offer this type of 
compliance option. Additionally, we note that EPA determined its 24-
hour backstop daily rate based on a review of the average emitting 
characteristics of most coal fired boilers in operation during 2021. 
New Hampshire determined the NOX RACT emission rates for the 
Merrimack Station boilers based on the emitting and operational 
characteristics of these specific units. In the GNP, the EPA observed 
that even units considered to be running their controls optimally had 
some days (most often less than 5% of days) where the rates were 
higher. However, the emission increases on these days were minimal. EPA 
used a similar methodology in employing the 95th percentile of observed 
daily operating emissions rates in selecting the backstop daily 
emissions rate for SCR-controlled coal boilers in the GNP.\15\ As an 
example, for a unit with a seasonal rate of 0.08 lbs NOX/
MMBtu, EPA determined that it would be expected that, on average, about 
4.7% of the daily rate values would be higher than 0.14 lb/MMBtu.
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    \13\ See footnote 3.
    \14\ As will be discussed later in this document, New Hampshire 
imposed separate, mass-based emissions limits for days with a 
startup or shutdown event.
    \15\ See 88 FR 36654, 36792 (June 5, 2023). We note that in 
contrast to the derivation of the GNP's daily limits, wherein EPA 
concluded that SCR optimized units (i.e., units that were running 
their SCR controls effectively) were those able to achieve a 0.08 
lbs/MMBtu ozone season emission rate, NH's NOX RACT 
evaluation points to the high percent reduction from uncontrolled 
levels as an indicator of effective operation of SCR controls. Using 
a 0.08 ozone season emission rate as a basis for setting emissions 
limits for MK1 and MK2 would have been inappropriate because of 
their much higher uncontrolled emission levels relative to the units 
governed by the GNP.
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    Comment: Sierra Club commented that NH's emissions limits for a 
different coal-fired electrical generating facility in the state, 
Schiller Station, are only slightly higher than those for Merrimack 
Station, despite the fact that the Schiller Station units controlled by 
SNCR, a less effective control strategy, inferring that Merrimack 
Station's more capable SCR controls are not being as effectively run as 
they should be.
    Response: EPA agrees that New Hampshire has imposed NOX 
emissions limits on the coal-fired boilers at Schiller Station of 0.25 
lbs/MMBtu that are only slightly higher than the limits imposed on the 
Merrimack Station units, despite the latter operating SCR controls, and 
the former operating less effective SNCR controls. However, this is not 
indicative of unduly lax

[[Page 34141]]

requirements for units MK1 and MK2 relative to the Schiller units, but 
rather, points to the higher uncontrolled NOX emission rates 
for the Merrimack Station units relative to the Schiller units. 
According to Table 1.1-3 of AP-42, the uncontrolled NOX 
emissions rate for Merrimack Station's bituminous fueled cyclone 
boilers is 33 lbs of NOX per ton of coal burned, which is 
the highest emission rate for any type of coal fired boiler listed 
within the table.\16\ Schiller Station operates two dry-bottom, wall-
fired coal boilers, which AP-42 indicates have an uncontrolled 
emissions rate of 22 lbs of NOX per ton of coal burned, and 
a fluidized bed boiler, which AP-42 indicates has an uncontrolled 
emissions rate of between 5.0 to 15.2 lbs of NOX per ton of 
coal burned. Given the differences in uncontrolled emission rates and 
NOX control technology of the coal-fired boilers at these 
facilities, comparisons of the NOX emissions rates do not 
offer an effective means of gauging the stringencies of the applicable 
emissions rates. The Merrimack Station units operate the more costly, 
more effective NOX control equipment compared to what the 
Schiller Station units run; technical resources that describe the 
control effectiveness of various NOX emission reduction 
control techniques rank SCR control systems higher than SNCR control 
systems.\17\
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    \16\ See Table 1.1-3, Emission Factors for SOX, 
NOX, and CO From Bituminous and Subbituminous Coal 
Combustion, within section 1.1 of AP-42: https://www.epa.gov/sites/default/files/2020-09/documents/1.1_bituminous_and_subbituminous_coal_combustion.pdf.
    \17\ See, for example, Table 1.1-2, NOX Control 
Options for Coal-fired Boilers within Section 1.1, Bituminous and 
Subbituminous Coal Combustion, of AP-42, and EPA's Air Pollution 
Control Technology Fact Sheets for SNCR and SCR control systems, 
included within the docket for this action.
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    Comment: Sierra Club commented that in light of recent information 
showing that SCR control systems can be operated at low-temperature 
levels that occur during periods of startup and shutdown with no 
detriment to control efficacy or longevity, New Hampshire does not need 
to allow the units to emit more on days when these operating modes 
occur by providing daily emission limits of 4.0 and 11.5 tons per day 
for MK1 and MK2, respectively.
    Response: In the aforementioned response to comments received on 
its proposed Regional Haze SIP, New Hampshire notes that approximately 
one fourth of the operating hours in the year prior to the 
establishment of the NOX RACT emission rates in question 
were hours spent in startup or shutdown modes when operating 
conditions, in particular temperature, did not permit the operation of 
the SCR control systems. The state therefore concluded that setting one 
overall emissions limit that combined the hours spent in startup and 
shutdown mode, during which the SCR controls would not operate, with 
the hours spent in steady state operation, during which the SCR 
controls would operate, would have necessitated issuance of an all-
encompassing emissions limit higher than the limit New Hampshire 
ultimately decided upon for times of steady state operation. By 
choosing to adopt separate limits for these operating modes, New 
Hampshire's emissions rate structure requires that MK1 and MK2 meet a 
lower emissions rate for the majority of the time it is operating, that 
being operation under steady state conditions with the SCR control 
equipment functioning. A separate alternate emission limit (AEL) 
applicable during startup and shutdown modes ensures that the emissions 
that occur during those times are also subject to an emissions cap as 
well as recordkeeping requirements to document the dates and time spent 
in startup or shutdown mode. As noted within the update to section 2 of 
the technical support document included within the docket for this 
action, the AEL in conjunction with requirements contained within Env-A 
1300 and the facility's Title V operating permit mean that the SCRs 
must be turned on expeditiously once high levels of coal loading begin 
in order to avoid exceeding the tons/calendar day limit of the AEL.
    Sierra Club refers to a sorbent injection technology that can 
reduce the operating temperature range of the SCR and potentially 
reduce NOX emissions at low loads. NHDES reviewed the 
provided references, which describe the technology as allowing the 
coal-fired boilers operated by Duke Power's Gibson facility to operate 
its SCRs at a lower temperature than would otherwise be possible, and 
also enable the coal boilers to run at low loads while still minimizing 
emissions. NHDES notes, however, that MK1 and MK2 SCRs are not designed 
to operate at lower temperatures, nor are the boilers intended to 
operate at low electrical output loads, and so even if modifications 
were made such that the SCR control equipment could function at lower 
temperature there would be little benefit, from an emissions reduction 
perspective, to installing additional controls to enable this. The 
small benefit in emissions reductions for operating the SCR at lower 
temperatures is partially due to the level and averaging period of the 
AEL, which significantly limits the time that these boilers can operate 
with high fuel input without the SCRs, and therefore limits the amount 
of total emissions because the units would exceed the 4 tons per day 
emission limit if they operated with high fuel input without the SCRs 
in operation.\18\ Therefore, NHDES concluded that a lowering of the 
temperature at which the SCR controls could operate during startup and 
shutdown would not justify the significant capital costs it would take 
to install the new control technology Sierra Club mentions. New 
Hampshire notes that in 2021, MK1 and MK2 operated for approximately 
2,155 hours and were started up approximately 26 times. Assuming that 
the sorbent injection technology mentioned in Sierra Club's comments 
could lower the temperature at which MK1 and MK2 could operate their 
SCR controls such that they could be used for an additional hour during 
startup, this would have resulted in a relatively minor, incremental 
emission reductions \19\ by allowing 26 additional hours of SCR 
operating time out of 2,155 overall boiler operating hours.
---------------------------------------------------------------------------

    \18\ For a further explanation and example of this behavior, see 
the TSD that accompanies this final action.
    \19\ EPA reviewed the difference in emissions between the last 
hour of non-SCR operation and the first hour of SCR operation and 
found that if MK1 could have begun SCR controls 1 hour earlier 
during each startup in 2021, 3.4 tons of NOX would have 
been prevented, and for MK2, 8.6 tons would have been prevented.
---------------------------------------------------------------------------

    We have reviewed Sierra Club's comment that additional emissions 
control technology be required for startup and shutdown operations, and 
New Hampshire's rationale for not requiring it, and agree with the 
state's conclusion that the additional cost of evaluating, installing, 
and operating control technology to limit emissions during startup and 
shutdown is unlikely to be economically feasible given the minimal 
amount of emissions it would curtail. Furthermore, the recordkeeping 
and reporting requirements of New Hampshire's NOX RACT 
regulation enable the state to effectively oversee operations at the 
facility, including operations during startup and shutdown. For 
example, the state's oversight requirements recently led to the 
issuance of an August 23, 2023 letter requesting more information 
regarding four exceedances of the startup emissions limit that occurred 
between December 8, 2021, and July 7, 2023.\20\ A

[[Page 34142]]

total of 16.4 tons of excess emissions occurred on these days, and the 
state is currently evaluating the appropriate enforcement response to 
these violations.
---------------------------------------------------------------------------

    \20\ A copy of New Hampshire's August 23, 2023 letter to Granite 
Shore Power is included in the docket for this action.
---------------------------------------------------------------------------

    Comment: Sierra Club also commented that New Hampshire's 
requirements are not sufficient for regional haze purposes.
    Response: This comment is not germane to the subject matter of this 
action which pertains to New Hampshire's NOX RACT 
requirements for coal-fired cyclone boilers and does not address 
regional haze requirements. Therefore, EPA is not addressing this 
comment here.

III. Final Action

    EPA is approving RACT requirements limiting NOX 
emissions from coal-fired cyclone boilers powering electrical 
generating units that are codified within New Hampshire Air Pollution 
Control Regulation Env-A 1300: Nitrogen Oxides (NOX) RACT, 
portions of New Hampshire's NOX RACT certifications for the 
2008 and 2015 ozone standards that pertain to requirements for coal-
fired cyclone boilers, and withdrawal from the SIP of two previously 
issued RACT orders containing emission limits for this equipment that 
are less stringent than what is contained within the provisions of Env-
A 1300 that we are approving within this action.

IV. Incorporation by Reference

    In this rule, the EPA is finalizing regulatory text that includes 
incorporation by reference. In accordance with requirements of 1 CFR 
51.5, the EPA is finalizing the incorporation by reference of portions 
of New Hampshire Air Pollution Control Regulation Env-A 1300, Nitrogen 
Oxides (NOX) RACT; specifically, incorporating by reference 
Env-A 1303.06(b) and (c) pertaining to the coal-fired cyclone boilers 
at Merrimack Station, as described in the amendments to 40 CFR part 52 
set forth below. The EPA has made, and will continue to make, these 
documents generally available through https://www.regulations.gov and 
at the EPA Region 1 Office (please contact the person identified in the 
FOR FURTHER INFORMATION CONTACT section of this preamble for more 
information). Therefore, these materials have been approved by EPA for 
inclusion in the State implementation plan, have been incorporated by 
reference by EPA into that plan, are fully federally enforceable under 
sections 110 and 113 of the CAA as of the effective date of the final 
rulemaking of EPA's approval, and will be incorporated by reference in 
the next update to the SIP compilation.\21\
---------------------------------------------------------------------------

    \21\ 62 FR 27968 (May 22, 1997).
---------------------------------------------------------------------------

    EPA is also finalizing the removal of provisions within Table (d) 
of 52.1520 pertaining to these coal-fired cyclone boilers by removing 
Permits ``Order ARD-97-001: Source specific NOX RACT Order 
for Public Service of New Hampshire, Bow, NH; state effective date 4/
14/1997'' and ``Order ARD-98-001: Source-specific NOX RACT 
order and discrete emission reduction protocols for Public Service of 
New Hampshire; state effective date 7/17/1998'' as described in the 
amendments to 40 CFR part 52 set forth below.

V. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, EPA's role is to approve state 
choices, provided that they meet the criteria of the Clean Air Act. 
Accordingly, this action merely approves state law as meeting Federal 
requirements and does not impose additional requirements beyond those 
imposed by state law. For that reason, this action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001); and
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act.
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, the rule does not have tribal implications and will not impose 
substantial direct costs on tribal governments or preempt tribal law as 
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).
    Executive Order 12898 (Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
Feb. 16, 1994) directs Federal agencies to identify and address 
``disproportionately high and adverse human health or environmental 
effects'' of their actions on minority populations and low-income 
populations to the greatest extent practicable and permitted by law. 
EPA defines environmental justice (EJ) as ``the fair treatment and 
meaningful involvement of all people regardless of race, color, 
national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies.'' EPA further defines the term fair treatment to mean that 
``no group of people should bear a disproportionate burden of 
environmental harms and risks, including those resulting from the 
negative environmental consequences of industrial, governmental, and 
commercial operations or programs and policies.''
    The New Hampshire Department of Environmental Services did not 
evaluate environmental justice considerations as part of its SIP 
submittal; the CAA and applicable implementing regulations neither 
prohibit nor require such an evaluation. EPA did not perform an EJ 
analysis and did not consider EJ in this action. Due to the nature of 
the action being taken here, this action is expected to have a neutral 
to positive impact on the air quality of the affected area. 
Consideration of EJ is not required as part of this action, and there 
is no information in the record inconsistent with the stated goal of 
E.O. 12898 of achieving environmental justice for people of color, low-
income populations, and Indigenous peoples.
    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a

[[Page 34143]]

copy of the rule, to each House of the Congress and to the Comptroller 
General of the United States. EPA will submit a report containing this 
action and other required information to the U.S. Senate, the U.S. 
House of Representatives, and the Comptroller General of the United 
States prior to publication of the rule in the Federal Register. A 
major rule cannot take effect until 60 days after it is published in 
the Federal Register. This action is not a ``major rule'' as defined by 
5 U.S.C. 804(2).
    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by July 1, 2024. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this action for the purposes of 
judicial review nor does it extend the time within which a petition for 
judicial review may be filed, and shall not postpone the effectiveness 
of such rule or action. This action may not be challenged later in 
proceedings to enforce its requirements. (See section 307(b)(2).)

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Nitrogen dioxide, Ozone.

    Dated: April 18, 2024.
David Cash,
Regional Administrator, EPA Region 1.

    Part 52 of chapter I, title 40 of the Code of Federal Regulations 
is amended as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

    Authority:  42 U.S.C. 7401 et seq.

Subpart EE--New Hampshire

0
2. In Sec.  52.1520:
0
a. Amend the table in paragraph (c) by revising the entry for ``Env-A 
1300'';
0
b. Amend the table in paragraph (d) by removing the entries for 
``Source specific NOX RACT order for Public Service of New 
Hampshire, Bow, NH'' and ``Source-specific NOX RACT order 
and discrete emission reduction protocols for Public Service of New 
Hampshire''; and
0
c. Amend the table in paragraph (e) by revising the entry for 
``Certifications for RACT for the 2008 and 2015 ozone standards''.
    The revisions read as follows:


Sec.  52.1520  Identification of plan.

* * * * *
    (c) * * *

                                     EPA-Approved New Hampshire Regulations
----------------------------------------------------------------------------------------------------------------
                                                     State effective   EPA approval date
         State citation            Title/subject           date               \1\              Explanations
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Env-A 1300.....................  NOX RACT.........      8/15/2018 and  9/6/2023, 88 FR    Regulation, effective
                                                            3/20/2023   60893.             8/15/2018, containing
                                                                                           emissions limits and
                                                                                           other requirements
                                                                                           for stationary
                                                                                           sources of nitrogen
                                                                                           oxides approved
                                                                                           except for sections
                                                                                           pertaining to coal-
                                                                                           fired cyclone boilers
                                                                                           at Env-A 1303.06(b)
                                                                                           and (c). Revisions
                                                                                           made to Env-A 1303.02
                                                                                           and 1303.04.
                                                                                           effective 3/20/2023.
                                                            8/15/2018  4/30/2024 [Insert  Requirements
                                                                        Federal Register   pertaining to coal-
                                                                        citation].         fired cyclone boilers
                                                                                           at Env-A 1303.06(b)
                                                                                           and (c).
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
\1\ In order to determine the EPA effective date for a specific provision listed in this table, consult the
  Federal Register notice cited in this column for the particular provision.

    (e) * * *

                                           New Hampshire NonRegulatory
----------------------------------------------------------------------------------------------------------------
                                     Applicable
   Name of nonregulatory SIP       geographic or     State submittal
           provision               nonattainment      date/effective   EPA approved date       Explanations
                                        area               date
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Certifications for RACT for the  Statewide........           9/6/2018  9/6/2023, 88 FR    RACT certifications
 2008 and 2015 ozone standards.                                         60893.             for stationary
                                                                                           sources of VOC and
                                                                                           NOX approved for
                                                                                           purposes of the 2008
                                                                                           and 2015 ozone
                                                                                           standards except for
                                                                                           NOX RACT requirements
                                                                                           pertaining to coal-
                                                                                           fired cyclone
                                                                                           boilers.
                                                             9/6/2018  4/30/2024 [Insert  NOX RACT
                                                                        Federal Register   certifications for
                                                                        citation].         the 2008 and 2015
                                                                                           ozone standards
                                                                                           pertaining to coal-
                                                                                           fired cyclone
                                                                                           boilers.
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------



[[Page 34144]]

[FR Doc. 2024-08713 Filed 4-29-24; 8:45 am]
BILLING CODE 6560-50-P