Document ID: EPA-HQ-OAR-2019-0424-0281
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2023-05-22T04:00Z

MEMORANDUM

TO:	Docket ID. No EPA-HQ-OAR-2019-0424
FROM:	Jen Bohman, EPA
DATE:	April 2023
SUBJECT: 	Facilities Potentially Impacted by the Proposed GWP Revisions to Table A-1 (Global Warming Potentials) 
 1.0 Background and Introduction for GWP Revisions
The EPA is proposing to update the Global Warming Potentials (GWPs) in Table A-1 to subpart A to match the GWPs published by the Intergovernmental Panel on Climate Change (IPCC) in Table 8.A.1 of the 2013 Fifth Assessment Report (AR5) and, for certain greenhouse gases (GHGs) that do not have chemical-specific GWPs listed in AR5, to adopt GWP values from the IPCC Sixth Assessment Report (AR6). The EPA is also proposing to revise and expand the set of default GWPs in Table A-1, which are applied to GHGs for which peer-reviewed chemical-specific GWPs are not available. Additional detail on these changes can be found in section II.A of the preamble to the Revisions and Confidentiality Determinations for Data Elements Under the Greenhouse Gas Reporting Rule supplemental notice of proposed rulemaking. This memorandum explains how these proposed changes are expected to affect the numbers of facilities and suppliers reporting to the Greenhouse Gas Reporting Program (GHGRP) and the change in burden that is expected to occur. Burden impacts are discussed as changes in the number of facilities reporting to a specific subpart. 
Facilities that report under the GHGRP (40 CFR part 98) use the GWPs in Table A-1 to subpart A to calculate their emissions in terms of carbon dioxide equivalents (CO2e). Section 1.0 describes how the changes to Table A-1 will affect reporters. Two kinds of reporters are described in this memorandum:
 Current reporters are those facilities that are already subject to the GHGRP and are currently reporting their emissions through the EPA's GHGRP emissions reporting system, e-GGRT. 
 New reporters are those facilities that are not currently required to report to the GHGRP but would become subject to the program as a result of the changes to Table A-1.
 1.1 How GWPs Affect Emissions and Applicability of the GHGRP
A change to the GWP for a GHG will change the calculated CO2e emissions or supply quantities of that gas, which could lead to a change in the number of facilities or suppliers that are subject to the GHGRP. The number of facilities or suppliers could change because certain subparts' applicability to a given facility or supplier is based on the amount of GHG that is consumed, generated, emitted, imported, or exported over a calendar year, expressed in CO2e. Carbon dioxide equivalent is a metric used to compare the emissions of various GHGs based on their GWP. Because different GHGs have different heat-trapping capabilities and atmospheric lifetimes, they are not directly comparable without translating emissions into a common unit of measure. The GWP is a measure of the total energy that a gas absorbs over a particular period of time (usually 100 years) compared to carbon dioxide, which has a GWP of 1.0. The CO2e for a specific gas is derived by multiplying the mass of the gas by its associated GWP. For example, methane currently has a GWP of 25. A facility that emits 1,000 tons of CO2 emits 1,000 tons per year of CO2e. A facility that emits 1,000 tons of methane emits 25,000 tons per year of CO2e.
As discussed in the proposed rule, the GWP values currently in Table A - 1 to part 98 are drawn both from the IPCC Fourth Assessment Report (hereinafter referred to as "AR4") and, for multiple GHGs that do not have GWPs listed in AR4, from AR5. We are proposing to revise the GWPs drawn from AR4 to reflect the updated values in AR5. The GWPs in Table A-1 that are currently drawn from AR5 would remain unchanged. 
Based on an updated understanding of the radiative efficiencies and atmospheric lifetimes of CO2 and many other GHGs, the IPCC in the 2013 Fifth Assessment Report updated the GWP values for many compounds, including: 
 methane (CH4), 
 nitrous oxide (N2O), 
 multiple fluorinated compounds, including hydrofluorocarbons, perfluorinated compounds, fluorinated ethers, perfluoropolyethers, and others,
 substances controlled by the Montreal protocol, and 
 certain hydrocarbons and other compounds with direct warming effects. 
The GWP values revised by the IPCC represent an increase in the GWP for CH4, a decrease for N2O, an increase for 41 fluorinated gases, and a decrease for 40 other fluorinated gases. 
The GHGs that are covered by the GHGRP are CO2, CH4, N2O, sulfur hexafluoride (SF6), nitrogen trifluoride (NF3), hydrofluorocarbons, perfluorocarbons, and multiple other fluorinated GHGs (which include, but are not limited to, fluorinated ethers, perfluoropolyethers, and perfluoroalkylamines). The GHGRP does not require reporting of emissions of the Montreal protocol substances or the hydrocarbons with direct effects (dimethylether, methylene chloride, and methyl chloride). Appendix A of this memorandum lists the compounds covered by the GHGRP along with the current GWPs and the proposed GWP revisions. 
In addition to updating the GWP values for GHGs currently in Table A-1, the EPA is also proposing to amend subpart A of part 98 to add new chemical-specific GWPs for several fluorinated GHGs (F-GHGs) to Table A-1 using the GWPs from the IPCC 2021 Sixth Assessment Report.[2] Currently, some source categories under 40 CFR part 98 provide calculation methodologies and reporting requirements for F-GHGs or fluorinated heat transfer fluids (F-HTFs) for which GWPs were not available in the IPCC assessment reports or other scientific assessments at promulgation. In the absence of chemical-specific GWPs, default GWPs based on the fluorinated GHG group are currently applied to these F-GHGs. The proposed update would replace these default GWPs with chemical-specific GWPs where chemical-specific GWPs are available in AR6.
The default GWPs for fluorinated gases in Table A-1 are also proposed to be revised by adding two new fluorinated GHG groups, modifying an existing group, and updating the existing default values to reflect the chemical-specific GWPs that are proposing to be adopted from AR5 and AR6. Appendix B of this memorandum provides the proposed new and revised F-GHG groups and their proposed new and revised GWPs.
The GWPs in Table A-1 to subpart A are primarily used for threshold calculations to determine rule applicability (40 CFR 98.2(b)) and for reporting total GHG emissions or supply quantities in CO2e for each facility or supplier (40 CFR 98.3(c)(4)). Revisions to the GWPs affect the calculation of CO2e, and thus any increase in the GWPs in a threshold analysis could cause a given facility or supplier to exceed the GHGRP reporting threshold. Additionally, decreases in the GWPs for GHGs may allow facilities to stop reporting to the GHGRP (or "off-ramp") if the total facility-level emissions (or quantity of GHG supplied) are less than 25,000 metric tons (mt) CO2e per year for five consecutive years or less than 15,000 mt CO2e per year for three consecutive years (40 CFR 98.2(i)). A change to a facility's reporting status would cause the facility to incur costs for monitoring, recordkeeping, and reporting emissions (if the facility becomes a new reporter) or may reduce the burden on the facility if they are able to off-ramp.
In this memorandum, the impacts of the proposed new or revised GWPs in Table A-1 to subpart A are evaluated based on the estimated number of reporters that would either be required to report or cease reporting under each subpart if the proposed changes are finalized. An initial broad analysis was performed to determine which subparts are expected to have burden changes due to the proposed GWPs. For certain subparts, the application of the proposed GWPs is not expected to result in significant changes to emissions or the number of reporters. The methodology, analysis, and results of this analysis are described in Section 2.0. A summary of burden impacts (i.e., facility counts) due to the GWP revisions is provided in Section 3.0. The methodologies used to determine burden impacts to current and new reporters for "included" subparts are described in Section 4.0. 
 2.0 Identification of Subparts Affected by the GWP Revisions in Subpart A 
This section describes the initial broad analysis that was performed to determine which subparts could potentially be affected by the proposed revisions to the GWPs in Table A-1.
 2.1 Review of Reporting Applicability and Thresholds
To determine which subparts could be affected by the proposed GWP changes (and therefore need further analysis to determine burden impacts), the EPA first reviewed the reporting applicability, threshold level, and GHGs emitted for each subpart. Certain subparts were omitted from further analysis if they were determined to be unaffected (or minimally affected) by changes in the GWPs.
The reporting provisions for the GHGRP are found in 40 CFR 98.2(a). There are four scenarios where a facility may be required to report:
 If a source category is listed in Table A-3 to subpart A, then there is no reporting threshold and a facility must report to the GHGRP if it contains the source category (40 CFR 98.2(a)(1)). The subparts in Table A-3 are known as "all-in" subparts. 
 If a source category is listed in Table A-4 to subpart A, the subpart is considered a "threshold" subpart because a facility that contains the source category must only report if the total emissions are greater than 25,000 mt CO2e from all applicable source categories (40 CFR 98.2(a)(2)). 
 A facility that does not contain a source category listed in Tables A-3 or A-4 and emits greater than 25,000 mt CO2e from all stationary combustion sources with an aggregated maximum rated heat input capacity greater than or equal to 30 million British thermal units per hour (mmBtu/hr) must report to subpart C (stationary fuel combustion) of part 98 only (40 CFR 98.2(a)(3)). 
 If a supplier category is listed in Table A-5 to subpart A, a facility that exceeds any applicable thresholds included in Table A-5 for that category must report all applicable Table A-5 supplier categories (40 CFR 98.2(a)(4)). 
Each GHG source category and their respective reporting applicability type (threshold, all-in, supplier, or combustion) is identified in Table 2.1-1.
Table 2.1-1. GHGRP Subpart and Source Categories
                                    Subpart
                              GHG Source Category
                            Reporting Applicability
                                       C
                  General Stationary Fuel Combustion Sources
                                  Combustion
                                       D
                            Electricity Generation
                                    All-in
                                       E
                            Adipic Acid Production
                                    All-in
                                       F
                              Aluminum Production
                                    All-in
                                       G
                             Ammonia Manufacturing
                                    All-in
                                       H
                               Cement Production
                                    All-in
                                       I
                           Electronics Manufacturing
                                   Threshold
                                       K
                             Ferroalloy Production
                                   Threshold
                                       L
                          Fluorinated Gas Production
                                   Threshold
                                       N
                               Glass Production
                                   Threshold
                                       O
                   HCFC-22 Production and HFC-23 Destruction
                                   All-in[1]
                                       P
                              Hydrogen Production
                                   Threshold
                                       Q
                           Iron and Steel Production
                                   Threshold
                                       R
                                Lead Production
                                   Threshold
                                       S
                         Lime Manufacturing (non-CEMS)
                                    All-in
                                       T
                             Magnesium Production
                                   Threshold
                                       U
                        Miscellaneous Uses of Carbonate
                   N/A  -  only reported with other subparts
                                       V
                            Nitric Acid Production
                                    All-in
                                       W
                       Petroleum and Natural Gas Systems
                                   Threshold
                                       X
                           Petrochemical Production
                                    All-in
                                       Y
                             Petroleum Refineries
                                    All-in
                                       Z
                          Phosphoric Acid Production
                                    All-in
                                      AA
                         Pulp and Paper Manufacturing
                                   Threshold
                                      BB
                          Silicon Carbide Production
                                    All-in
                                      CC
                            Soda Ash Manufacturing
                                    All-in
                                      DD
            Use of Electric Transmission and Distribution Equipment
                                   All-in[2]
                                      EE
                          Titanium Dioxide Production
                                    All-in
                                      FF
                            Underground Coal Mines
                                   All-in[3]
                                      GG
                                Zinc Production
                                   Threshold
                                      HH
                        Municipal Solid Waste Landfills
                                   All-in[4]
                                      II
                        Industrial Wastewater Treatment
                                   Threshold
                                      LL
                     Suppliers of Coal based Liquid Fuels
                                   Supplier
                                      MM
                        Suppliers of Petroleum Products
                                   Supplier
                                      NN
               Suppliers of Natural Gas and Natural Gas Liquids
                                   Supplier
                                      OO
                   Suppliers of Industrial Greenhouse Gases
                                   Supplier
                                      PP
                          Suppliers of Carbon Dioxide
                                   Supplier
                                      QQ
          Importers / Exporters of Equipment Pre-charged with F-GHGs
                                   Supplier
                                      RR
                   Geologic Sequestration of Carbon Dioxide
                                    All-in
                                      SS
         Manufacture Electric Transmission and Distribution Equipment
                                    All-in
                                      TT
                          Industrial Waste Landfills
                                   Threshold
                                      UU
                          Injection of Carbon Dioxide
                                    All-in
 HFC-23 destruction processes that are not collocated with a HCFC-22 production facility and that destroy more than 2.14 mt of HFC-23 per year.
 Electrical transmission and distribution equipment use at facilities where the total nameplate capacity of SF6- and PFC-containing equipment exceeds 17,820 pounds, as determined under 40 CFR 98.301.
 Underground coal mines liberating 36,500,000 actual cubic feet of CH4 or more per year.
 Municipal solid waste landfills that generate CH4 in amounts equivalent to 25,000 mt CO2e or more per year.
      
For all-in subparts, the impacts from the proposed GWP updates to Table A-1 were evaluated for current reporters and reporters who had previously met the off-ramp requirements to exit the GHGRP (and would therefore be considered "new" reporters if they were to begin reporting to the GHGRP again). Current reporters may be impacted by the revised GWPs through their ability to off-ramp from the GHGRP. Those subparts where the reported emissions are expected to have a net decrease (i.e., those with significant N2O or certain F-gas emissions) were further reviewed to determine the number of current reporters with the potential to off-ramp. For subparts E, F, O, and V, the emissions changes due to the revised GWPs were estimated for current reporters and compared to the off-ramp thresholds of 25,000 mt CO2e and 15,000 mt CO2e. It was assumed that any facility with recalculated emissions that would fall below the off-ramp threshold would no longer report to the GHGRP. Additionally, for those subparts where reported emissions are expected to have a net increase due to the AR5 GWP updates, emissions were recalculated to determine if any facilities that are currently in the process of off-ramping will no longer meet the off-ramp thresholds.
For all-in subparts with a net increase in reported emissions due to the proposed GWP changes, emissions from the reporters who had previously exited the program due to off-ramping were recalculated. For those facilities whose recalculated emissions exceeded the 25,000 mt CO2e threshold to resume reporting to the GHGRP per 40 CFR 98.2(i)(1), it was assumed that they would be required to re-enter the program. Subpart DD, FF, HH, and SS reporters who previously off-ramped were evaluated for potential return to the GHGRP.
For threshold subparts, the impacts from the proposed GWP updates to Table A-1 were evaluated for current and new reporters. Similar to all-in subparts, current reporters' emissions were recalculated using the proposed GWPs to determine their ability to off-ramp. For new reporters, both facilities that never exceeded the reporting threshold for their applicable subparts and reporters who had previously met the off-ramp requirements to exit the GHGRP were reviewed for potential entry into the GHGRP. Threshold subparts with an expected change in reported emissions due to the proposed GWP changes included subparts I, K, L, T, W, II, and TT. For supplier subparts, impacts from the proposed GWP updates to Table A-1 were reviewed on a subpart-by-subpart basis, as each supplier subpart has their own threshold. Subparts OO and QQ were identified for further review. 
The EPA completed a review of the reporting applicability and thresholds and determined that further evaluation was not needed for the following subparts:
 Subparts LL, MM, NN, PP, RR, and UU  -  The revised GWPs have no effect on these subparts because CO2 is the sole GHG reported. GWP is a measure of the heat trapped by specific gas(es) as compared to the heat trapped by CO2. Actual CO2 emissions are not converted to CO2e, and thus GWP has no bearing on the applicability in these cases.
 Subparts G, P, U, Z, BB, EE, and GG  -  Although CO2, CH4, and/or N2O combustion emissions are required to be reported, the sole emission type reported under these specific subparts is CO2 process emissions. Combustion emissions are required to be reported under subpart C. Any change to combustion emissions associated with these subparts is incorporated into the impact analysis performed on subpart C (as discussed in Section 2.2).
 Subparts H, N, R, and CC  -  Only CO2 process and CO2 combustion emissions are reported under the subpart. Additional combustion emissions are required to be reported under subpart C. Any change to combustion emissions associated with these subparts is incorporated into the impact analysis performed on subpart C (as discussed in Section 2.2).
 2.2 Fuel Combustion Emissions
The GHGs from stationary fuel combustion are CO2, CH4, and N2O. To determine total CO2e, CH4 and N2O contributions are multiplied by their respective GWPs and added to the CO2 value. The proposed AR5 GWPs would result in the following changes:
 CH4 GWP increases from 25 to 28.
 N2O GWP decreases from 298 to 265. 
The EPA determined that for stationary fuel combustion sources, the increase in the CH4 GWP would be offset by the decrease in the N2O GWP, such that the overall change in CO2e from the adoption of AR5 GWPs would be negligible for stationary fuel combustion. 
For example, for coal combustion, there is only a 0.02% decrease in CO2e as a result of the change to the GWP of CH4 and N2O emissions resulting from combustion, and for natural gas, there was a 0.001% decrease. The last row of Table 2.2-1 provides detail for these calculations.
Table 2.2-1. Example Emission Calculation for 100 Million BTU/hour Combustion Unit
                          Identifier for
Methodology
                        Description and/or
Methodology
                                Anthracite Coal
                                  Natural Gas
                                       A
CO2 EF (kg CO2/mmBTU)
                                    103.50
                                     53.02
                                       B
CH4 EF (kg CH4/mmBTU)
                                   1.10E-02
                                   1.00E-03
                                       C
Current GWP for CH4
                                      25
                                       D
Revised GWP for CH4
                                      28
                                       E
N2O EF (kg N2O /mmBTU)
                                   1.60E-03
                                   1.00E-04
                                       F
Current GWP for N2O
                                      298
                                       G
Revised GWP for N2O
                                      265
                                       H
Current CH4 CO2e
(B*C)
                                     0.275
                                     0.025
                                       I
Revised CH4 CO2e
(B*D)
                                     0.308
                                     0.028
                                       J
Current N2O CO2e
(E*F)
                                     0.477
                                     0.030
                                       K
Revised N2O CO2e
(E*G)
                                     0.424
                                     0.027
                                       L
Current Total CO2e
(A+H+J)
                                    104.25
                                    53.0748
                                       M
Revised Total CO2e
(A+I+K)
                                    104.23
                                    53.0745
                                       
Percent Change
((M-L)/L)
                                    -0.02%
                                    -0.001%

After reviewing all Table C-1 fuels, the EPA determined that stationary fuel combustion emissions could be omitted from further analysis because there are minimal changes in CO2e from the adoption of the AR5 GWPs for CH4 and N2O. In addition to subpart C, subparts where non-CO2 GHG emissions were primarily from combustion sources include subparts D, Q, S, X, Y, and AA.
 
 2.3 Results of Broader Analysis
Table 2.5-1 lists all of the GHGRP subparts and the rationale for including or excluding the subpart in the current and new reporter impact analysis described in Section 4.0.
Table 2.3-1. Rationale for GHG Subpart Selection for Impact Analysis
                                    Subpart
            Excluded / Included in Current Reporter Impact Analysis
              Excluded / Included in New Reporter Impact Analysis
                                   Rationale
C
                                   Excluded
                                   Excluded
Non-CO2 GHG emissions primarily from combustion
D
                                   Excluded
                                   Excluded
Non-CO2 GHG emissions primarily from combustion
E
                                   Included
                                   Excluded
Expected decrease in CO2e
F
                                   Included
                                   Excluded
Expected decrease in CO2e
G
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
H
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
I
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on GHG mix
K
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on GHG mix
L
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on GHG mix
N
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
O
                                   Included
                                   Excluded
Expected decrease in CO2e
P
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
Q
                                   Excluded
                                   Excluded
Non-CO2 GHG emissions primarily from combustion
R
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
S
                                   Excluded
                                   Excluded
Non-CO2 GHG emissions primarily from combustion
T
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on GHG mix
U
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
V
                                   Included
                                   Excluded
Expected decrease in CO2e
W
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on GHG mix
X
                                   Excluded
                                   Excluded
Non-CO2 GHG emissions primarily from combustion
Y
                                   Excluded
                                   Excluded
Non-CO2 GHG emissions primarily from combustion
Z
                                   Excluded
                                   Excluded
CO2 emissions only
AA
                                   Excluded
                                   Excluded
Non-CO2 GHG emissions primarily from combustion
BB
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
CC
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
DD
                                   Included
                                   Included
Expected increase in CO2e
EE
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
FF
                                   Excluded
                                   Included
Expected increase in CO2e
GG
                                   Excluded
                                   Excluded
CO2 process and/or combustion emissions only
HH
                                   Included
                                   Included
Expected increase in CO2e
II
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on GHG mix
LL
                                   Excluded
                                   Excluded
CO2 is the only GHG reported
MM
                                   Excluded
                                   Excluded
CO2 is the only GHG reported
NN
                                   Excluded
                                   Excluded
CO2 is the only GHG reported
OO
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on F-gas mix
PP
                                   Excluded
                                   Excluded
CO2 is the only GHG reported
QQ
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on F-gas mix
RR
                                   Excluded
                                   Excluded
CO2 is the only GHG reported
SS
                                   Included
                                   Included
Expected increase in CO2e
TT
                                   Included
                                   Included
Expected change in CO2e  -  increase/decrease depends on GHG mix
UU
                                   Excluded
                                   Excluded
CO2 is the only GHG reported

 3.0 Summary of Impacts
Table 3-1 provides the estimated changes to the number of affected facilities due to the proposed revised GWPs. Of the 17 subparts identified for further analysis, one subpart (subpart V) is expected to see a decrease in the number of facilities reporting to the GHGRP and six subparts (subparts W, DD, HH, II, OO, and TT) are projected to have an increase in the number of reporters to the GHGRP. The remaining 10 subparts are not expected to see an impact to their respective reporting facilities due to the proposed GWP revisions to Table A-1. Details on how the facility counts in Table 3-1 were determined is provided in Section 4.0.
Table 3-1. Summary of Facility Count Changes Due to the GWP Revisions
                                    Subpart
     Number of Current Reporters Eligible to Off-Ramp Due to GWP Revisions
                 Number of New Reporters Due to GWP Revisions
E
                                       0
                                       0
F
                                       0
                                       0
I
                                       0
                                       0
K
                                       0
                                       0
L
                                       0
                                       0
O
                                       0
                                       0
T
                                       0
                                       0
V
                                       1
                                       0
W
                                       0
                                      188
DD
                                       0
                                       2
FF
                                       0
                                       0
HH
                                       0
                                       6
II
                                       0
                                       2
OO
                                       0
                                       1
QQ
                                       0
                                       0
SS
                                       0
                                       0
TT
                                       0
                                       1
Total
                                       1
                                      200

 4.0 Methodology for Estimating Impacts to Current and New Reporters
For the subparts identified in Section 2.0 of this memorandum, the EPA performed an in-depth evaluation to determine the expected number of facilities entering and leaving the GHGRP due to the proposed GWP updates to Table A.1. 
The methodology used for these analyses compared subpart-specific process emissions before and after the change in GWPs to determine current reporter impacts and/or new reporter impacts as shown in Table 3-1. GHG emissions were obtained for Reporting Year (RY) 2020 and prior years from the EPA's Envirofacts dataset (https://enviro.epa.gov/, based on data frozen as of August 7, 2021). This section of the memorandum describes the analyses performed for each subpart.
 4.1 Subpart E
40 CFR part 98 subpart E (subpart E) applies to all adipic acid production facilities in the United States, beginning in RY2010. Adipic acid production facilities only report N2O emissions to subpart E. No CO2 or CH4 emissions result from the production of adipic acid. There is no initial reporting threshold. Through RY2020, no subpart E facilities have stopped reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2). However, one subpart E facility shut down all adipic acid operations in 2015.
For subpart E, the following GWP change is expected to affect reported emissions: 
Table 4.1-1. Applicable GWP Change for Subpart E
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
N2O
298
265
Decrease
4.1.1 Current Reporters
The methodology used for subpart E was simplified because there have only been three facilities subject to subpart E since RY2010, with one facility ceasing all adipic acid operations after RY2015. 
For subpart E, the EPA reviewed facility-level emissions for both subpart E facilities from RY2016 to RY2020, using the current GWPs and the new AR5 GWPs. These are shown in Table 4.1-2 and Table 4.1-3, respectively.
Table 4.1-2. Total Emissions from RY2016-RY2020 Using Current GWPs
                                  Facility ID
                              Applicable Subparts
                   Yearly Emissions (CO2e using current GWP)
                                       
                                       
                                     2016
                                     2017
                                     2018
                                     2019
                                     2020
1001781
C, E, V
2,054,583 
1,796,990 
 1,819,232 
1,700,530 
1,719,306 
1004962
C, E, P, V, TT
8,209,395 
8,459,420 
11,584,960 
6,590,476 
 9,192,846 

Table 4.1-3. Total Emissions from RY2016-RY2020 Using AR5 GWPs
                                  Facility ID
                              Applicable subparts
                    Yearly emissions (CO2e using AR5 GWPs)
                                       
                                       
                                     2016
                                     2017
                                     2018
                                     2019
                                     2020
1001781
C, E, V
 1,910,924 
 1,674,560 
1,694,766 
 1,595,910 
 1,612,504 
1004962
C, E, P, V, TT
 7,419,714 
 7,644,929 
10,428,564 
 5,984,227 
 8,284,510 

As shown in Table 4.1-3, neither of the two subpart E facilities are expected to off-ramp, regardless of the change in GWPs. As a result, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart E.
 4.2 Subpart F
40 CFR part 98 subpart F (subpart F) is a direct emitter subpart and requires reporting of GHG emissions from primary aluminum production facilities. Primary aluminum production is defined as one that "...manufactures primary aluminum using the Hall-Héroult manufacturing process." Subpart F does not apply to sources in the secondary aluminum production industry, which recover aluminum from scrap. 
Subpart F is not subject to a reporting threshold; all primary aluminum production facilities must report as of RY2010. As of RY2020, there were three companies that operated seven primary aluminum smelters. The primary aluminum production industry currently does not use continuous emission monitoring systems (CEMS) to monitor their CO2 emissions. Thus, all facilities report process emissions under subpart F and combustion emissions under subpart C. One facility also reports under subpart D for electricity generation, and another facility reports under subpart TT for industrial waste landfills. 
The GHG emissions from this source category include CO2, perfluoromethane (CF4), and perfluoroethane (C2F6) process emissions under subpart F, and CO2, CH4 and N2O combustion emissions under subpart C. Under subpart D for electric generation, one facility reports CO2, CH4 and N2O, and under subpart TT industrial waste landfills, one facility reports CH4. 
For subpart F, the following GWP changes are expected to affect reported process emissions: 
Table 4.2-1. Applicable GWP Changes for Subpart F Process Emissions
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
CF4
7,390
6,630
Decrease
C2F6
12,200
11,100
Decrease

4.2.1 Current Reporters
Historically, no subpart F facility has stopped reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2); a few facilities have stopped reporting under subpart F due to ceasing primary aluminum production. 
Subpart F GHG process emissions for each facility were calculated using the revised AR5 GWP values in Table 4.2-1 above and compared to the RY2020 subpart F process emissions to determine if there was a change in burden. 
Because there are only potential decreases in subpart F process emissions attributable to the AR5 GWP values, there are no scenarios under which new subpart F reporters could result. As such, the evaluation to determine any change in burden associated with the AR5 GWP values was limited to an off-ramp analysis.
Changes to CH4 and N2O combustion emissions were assumed to be insignificant due to an increase in the CH4 factor and a decrease in the N2O factor. Thus, combustion emissions for subparts C and D were not included in the evaluation, as changes were determined to be negligible (see Section 2.2).
Facilities where CO2 subpart F process emissions exceeded a conservative value of 50,000 mt CO2e in RY2020 did not require further evaluation, as the AR5 GWP changes (i.e., decreases) are not large enough to affect these facilities' reporting statuses. As such, subpart TT emissions from facility 1003562 are not required for this analysis. Potential increases in TT emissions for this facility (i.e., CH4 factor is going up under AR5) would only further limit its ability to off-ramp.
Table 4.2-2 presents the subpart F process emissions of CO2, CF4, and C2F6 as CO2e for the seven facilities that reported for RY2020. Annual CO2 subpart F process emissions alone reported by each facility were greater than 100,000 mt CO2e per year. 
Table 4.2-2. Burden Impacts for Existing Subpart F Reporters
                                  Facility ID
              RY2020 subpart F Process CO2e  -  As Reported
(mt)
                RY2020 subpart F Process CO2e  -  AR5 GWP
(mt)
1001877
 368,670 
 356,264 
1002112
 234,557 
 228,638 
1006666
 538,254 
 517,114 
1003562
 560,793 
 519,402 
1006853
 904,946 
 846,698 
1005534
 496,756 
 476,855 
1012517
 252,716 
 249,949 

The AR5 GWP decreases are not expected to decrease the reporting burden for subpart F facilities. Subpart F process emissions are well over the off-ramp thresholds and no facilities have been identified for the potential to off-ramp. As a result, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart F.
 4.3 Subpart I
40 CFR part 98 subpart I (subpart I) requires reporting of GHG emissions from the electronics industry. This industry uses multiple long-lived fluorinated GHGs, as well as N2O during manufacturing of electronic devices, including liquid crystal displays (LCDs), microelectro-mechanical systems (MEMS), photovoltaic cells (PV), and semiconductors (including light-emitting diodes [LEDs]). Many fluorinated GHGs have high GWPs which result in high levels of CO2e from potentially small emissions.
Currently, an electronic manufacturing facility is required to begin reporting if it is estimated to emit 25,000 mt CO2e or more in combined emissions from subpart I and all other applicable source categories in a calendar year. Facilities that are subject to reporting under subpart I may stop reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2).
Table 4.3-1 lists AR5 GWP changes expected to affect reported CO2e for subpart I. 
Table 4.3-1. Applicable AR5 GWP Changes for Subpart I
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
N2O
298
265
Decrease
SF6
22,800
23,500
Increase
NF3
17,200
16,100
Decrease
PFC-14 (Perfluoromethane)
7,390
6,630
Decrease
PFC-116 (Perfluoroethane)
12,200
11,100
Decrease
PFC-218 (Perfluoropropane)
8,830
8,900
Increase
PFC-318 (Perfluorocyclobutane)
10,300
9,540
Decrease
PFC-5-1-14 (Perfluorohexane, FC-72)
9,300
7,910
Decrease
PFPMIE (HT-70)
10,300
9,710
Decrease
HFC-23
14,800
12,400
Decrease
HFC-32
675
677
Increase
HFC-125
3,500
3,170
Decrease
HFC-134a
1,430
1,300
Decrease
HFC-41
92
116
Increase
HFC-143a
4,470
4,800
Increase
HFE-449s1 (HFE-7100) Chemical blend
297
421
Increase

It is expected that emissions of any fluorinated GHGs that would be added in Table A-1 to subpart A from AR6 are already reported under subpart I. Any gases that are not in the picklist of commonly used gases included in the subpart I reporting form must be manually entered by reporters as an "other" gas with a standard grouping and GWP selected by the reporter to best calculate CO2e based on the gas's chemical makeup. CO2e from gases added to Table A-1 would be calculated by their specific GWP in the future instead of using the standard GWP of the GHG groups they are assigned to by reporters.
For subpart I, the following AR6 changes are expected to affect reported CO2e based on RY2020 data:
Table 4.3-2. Applicable AR6 GWP Changes for Subpart I
GHG
Current F-GHG Group GWP
AR6 GWP
Change
HFE-7300
270
405
Increase
HFE-7500
270
13
Decrease

4.3.1 Current Reporters
In addition to the GWP changes being evaluated, the EPA has also recently proposed revisions to the subpart I rule (87 FR 36920, June 21, 2022). One of the proposed changes for subpart I is adding a consumption-based calculation option for facilities to determine whether they are subject to begin part 98 reporting. Facilities would be able to choose between the current calculation options based on manufacturing capacity and this new calculation option to determine their applicability. Some of the other proposed changes could impact facility emissions. These proposed changes include:
 Updating the emission factor tables to reflect new data published in the 2019 refinement to the 2006 IPCC guidelines as well as the data collected via the two triennial Technology Assessment Reports received to date;
 Updating the default destruction removal efficiency (DRE) values;
 Accounting for perfluoromethane generated in abatement devices; and
 Updates to the stack test methodology.
In the first step of our analysis, we evaluated RY2020 emissions from current subpart I reporters and recalculated as necessary based on the proposed subpart I rule changes, using the current published GWPs from Table A-1 to subpart A. We used the proposed emission factor updates to recalculate emissions for each evaluated reporter.
It was not possible to predict the effect on emissions of several other proposed subpart I changes. We do not have access to facilities' DRE calculations and we have no way of knowing how many facilities would choose the revised stack test method to calculate emissions under subpart I, or how many facilities would choose the new consumption-based method to calculate subpart I emissions in terms of applicability. However, a previous analysis of the proposed subpart I changes concluded that the calculated fab-wide DRE's are expected to increase on average, which would lead to an expected decrease in emissions for abated facilities (and would have no impact on non-abated facilities).
When recalculating emissions based on the proposed emission factor updates, we looked only at facilities with total combined emissions of 40,000 mt CO2e or less. This is because facilities with emissions greater than 40,000 mt CO2e would not become eligible to exit the program as a result of the anticipated change in GWPs, so no change in burden is expected for those facilities. Of the 48 facilities that reported under subpart I for RY2020, 14 had total combined emissions of 40,000 mt CO2e or less. These 14 facilities are listed in Table 4.3-3 with their reported total CO2e, subpart I CO2e, fab type and abatement status. 
Table 4.3-3. Subpart I Facilities with Current Total Emissions < 40,000 mt CO2e
                                  Facility ID
                           Total Emissions (mt CO2e)
                              Subpart I Emissions
                                   (mt CO2e)
                                   Fab Type
                                    Abated?
1012992

2,545
1,023
Semiconductor
(200 mm, 300 mm)
No
1009928
13,630
8,026
Semiconductor
(200 mm)
Yes
1004746
14,360
12,402
Semiconductor
(150 mm)
Yes
1004412
18,219
697
LCDs/MEMs/PVs
No
1009951
19,520
17,224
Semiconductor
(150 mm)
No
1009581
22,665
16,873
Semiconductor
(200 mm)
No
1009606
24,310
15,940
Semiconductor
(300 mm)
Yes
1009580
27,943
24,803
Semiconductor
(200 mm)
Yes
1008930

29,300
21,326
Semiconductor
(200 mm)
No
1003759
32,090
26,716
Semiconductor
(150 mm, 200 mm);
LCDs/MEMs/PVs
Yes
1009735
32,848
28,646
Semiconductor
(150 mm)
No
1010241
33,957
29,570
Semiconductor
(150 mm, 200 mm);
MEMS
No
1010033
36,093
33,428
Semiconductor
(150 mm)
No
1010005
37,086
32,215
Semiconductor
(200 mm)
Yes
Note: Shaded rows indicate facilities whose emissions did not necessitate further analysis (explained in the paragraphs below).
A previous analysis of the proposed subpart I changes concluded that, on average, emissions from semiconductor fabs will decrease due to the proposed subpart I changes and from the GWP changes based on the ratios of gases emitted from these fabs. Therefore, we conclude that any semiconductor fabs with emissions below 15,000 mt CO2e will remain below the 15,000 mt CO2e threshold to begin off-ramping and will not experience a change in burden as a result of either rule change.
Facility 1004412 is in the process of off-ramping from the program, with their emissions below 25,000 mt CO2e. In RY2020, 17,504 mt CO2e of emissions was attributed to carbon dioxide reported under subpart C. This leaves only 715 mt CO2e of emissions that would potentially be impacted by GWP changes from all reported subparts. The anticipated GWP changes will not have a significant enough impact on this facility's emissions to change the reporting status of this facility, so the CO2e was not recalculated for this facility.
This leaves 10 current subpart I facilities that were included in the analysis. For each selected unabated semiconductor fab, we recalculated RY2020 emissions by applying the predicted average percent change of each reported gas by wafer size as a result of the proposed emission factor changes, which were calculated in a previous analysis. For abated semiconductor fabs, the DRE was factored into the calculated average percent change in emissions of each gas that was reported as abated.
There are no subpart I emission factor changes proposed for LCD, PV, or MEMS fabs, so emissions from these fabs did not need to be recalculated to address subpart I rule changes. The proposed GWP changes would still impact the CO2e reported for LCD, PV, and MEMS fabs.
We then evaluated the current reporting facilities' emissions changes that would result from the AR5 GWP changes. Although there are many gases reported under subpart I, only those listed in Table 4.3-1 will have GWP changes, so only emissions from the gases listed in Table 4.3-1 were recalculated from the estimated subpart I emissions calculated as described above. The 10 subpart I facilities selected for analysis also report emissions from fossil-fuel combustion under subpart C. Since the GWPs for CH4 and N2O were also updated in AR5, the reported subpart C CH4 and N2O emissions were recalculated using the AR5 GWPs. Where the CO2e for a facility decreases, we determined if the decrease is likely to result in that facility becoming eligible to off-ramp (40 CFR 98.2(i)(1) and 98.2(i)(2)) when they would not have been eligible to off-ramp due to the anticipated subpart I rule changes alone.
Where the CO2e for a facility increases, we determined if the increase would be likely to prevent that facility from off-ramping based on the recalculated emissions based on the proposed subpart I rule changes (i.e., facilities that have been reporting facility-wide emissions below 25,000 mt CO2e for one or more years but are not yet eligible for off-ramping) due to the GWP changes.
The proposed subpart I emission factor changes would cause the CO2e to increase for five facilities and decrease for five facilities. The AR5 GWP changes would cause the CO2e to decrease for all but one facility.
Currently, 3 of the 10 evaluated subpart I facilities (1009951, 1009581, and 1009606) emit below 25,000 mt CO2e, and these facilities either already qualify to off-ramp or may be eligible to off-ramp in the next three years. The recalculated emissions based on the proposed subpart I emission factor changes (using the current GWPs) showed that none of the 10 facilities increased above or decreased below this 25,000 mt CO2e threshold line. The facilities also did not increase above or decrease below this threshold line when emissions were recalculated again using AR5 GWPs, as shown in Table 4.3-4.
Table 4.3-4. Subpart I Emissions Impact of AR5 GWP Changes
Facility ID
Proposed Subpart I Rule,
With Current Part 98 GWPs
Proposed Subpart I Rule,
With AR5 GWPs
Difference
(mt CO2e)

Total Emissions 
(mt CO2e)
Subpart I Emissions 
(mt CO2e)
Total Emissions 
(mt CO2e)
Subpart I Emissions 
(mt CO2e)

1009951
19,288
16,992
17,976
15,680
-1,312
1009581
23,164
17,372
21,854
16,062
-1,310
1009606
21,175
12,805
20,100
11,730
-1,074
1009580
27,986
24,846
27,558
24,418
-429
1008930
29,505
21,531
28,308
20,334
-1,197
1003759
32,184
26,810
30,589
25,215
-1,595
1009735
32,411
28,209
30,269
26,067
-2,142
1010241
34,030
29,643
33,896
29,509
-134
1010033
35,999
33,334
36,550
33,885
551
1010005
35,314
30,443
32,882
28,012
-2,431

Subpart I CO2e values were lower when calculated with AR5 GWPs for 9 out of 10 facilities, but this change does not have an impact on the reporting status of any current subpart I facility. We conclude that the proposed adoption of the AR5 GWPs would not have any impact on the burden for existing subpart I facilities.
Once the burden analysis for GWP changes from AR5 was complete, subpart I CO2e estimates were recalculated using the AR6 GWPs for those gases that EPA has proposed be added to Table A-1 for the first time. Since these gases would be reported under subpart I as F-HTFs, which are not calculated using emission factors based on fab type, this analysis was conducted for all current subpart I facilities with total facility emissions of 40,000 mt CO2e or less. Facilities with emissions greater than 40,000 mt CO2e would not become eligible to exit the program as a result of these added GWPs, so no change in burden is expected for those facilities. The change in burden to current facilities as a result of adding GWPs from AR6 in addition to revising GWPs according to AR5 was then revaluated for subpart I.
Of the 10 subpart I facilities selected for evaluation, only 2 are expected to be affected by assigning GWPs for the additional compounds listed in AR6, as shown in Table 4.3-5.
Table 4.3-5. Subpart I Emissions Impact of AR6 GWP Changes
Facility ID
Total Emissions (mt CO2e)
Difference 
(mt CO2e)

Proposed Subpart I Rule,
With AR5 GWPs
Proposed Subpart I Rule,
With AR6 GWPs

                                    1009606
20,100
19,663
-437
                                    1010241
33,896
33,895
-1

The AR6 GWPs have little impact on subpart I CO2e for these two facilities. The proposed AR6 GWPs would not result in the CO2e of any existing subpart I reporters increasing above or decreasing below the 25,000 mt CO2e threshold to begin off-ramping. 
As a result, there is no change to the number of affected facilities due to the proposed revised AR5 and AR6 GWPs for subpart I for current reporters.
4.3.2 New Reporters
Any facility that has previously met the emission requirements to off-ramp is required to begin reporting again if their facility-wide emissions exceed 25,000 mt CO2e for any year thereafter. Table 4.3-6 lists the seven subpart I facilities that have off-ramped from the program to date that were examined for this analysis, along with their reported CO2e and fab type. 
Table 4.3-6. Off-Ramped Subpart I Facilities
                                  Facility ID
                 Total Emissions from Most Recent RY (mt CO2e)
                                   Fab Type
1001199
1,965
MEMS
1009626
8,548
Semiconductor
1010317
13,351
Semiconductor
1010579
18,569
Semiconductor
1011671
7,806
Semiconductor
1011887
11,951
Semiconductor
1011905
223
Semiconductor

If the proposed subpart I changes are finalized, electronics manufacturing facilities will have a choice between using calculations based on their manufacturing capacity or using calculations based on their gas consumption to determine their emissions in terms of applicability to subpart I. Since MEMS fabs have a high ratio of SF6 emissions and the GWP for SF6 is increasing, it is possible that additional MEMS facilities would become subject to subpart I as a result of the AR5 GWP changes.

Although facilities would be more likely to use the applicability calculations based on gas consumption (since this would result in a lower estimate than the calculation method based on capacity), we do not have access to consumption data for any electronics manufacturing facilities that could potentially become subject to subpart I. However, the manufacturing capacity of electronics facilities is estimated in World Fab Forecast (WFF). We reviewed the WFF data to determine whether there are any MEMS facilities that could potentially become subject to the GHGRP. Using the proposed emission factors, the AR5 GWPs, and the 25,000 mt CO2e applicability threshold, we calculated the capacity threshold at which a MEMS facility would become subject to subpart I. Any MEMS facilities with a capacity listed in the WFF that is greater than our calculated capacity threshold could become subject to the GHGRP. Although the 25,000 mt CO2e applicability threshold is for the total emissions from the facility (not just from subpart I), it should also be noted that the CO2e that would have been calculated using the WFF capacity data would likely be higher than the CO2e the facilities would calculate for their subpart I emissions estimate if they choose to use the consumption-based calculation method to determine applicability.

As illustrated by Table 4.3-6, six of the seven off-ramped facilities are semiconductor manufacturing facilities, which, based on a previous analysis, are predicted to experience a decrease in CO2e from both the proposed subpart I rule changes and the proposed GWP changes. None of the semiconductor manufacturing facilities are expected to exceed the 25,000 mt CO2e threshold that requires a facility to recommence reporting to the GHGRP.

One off-ramped facility (1001199) manufactured MEMS rather than semiconductors. A previous analysis concluded that MEMS facilities are expected to experience an increase in emissions as a result of the proposed GWP changes. However, this facility has emissions of just 1,965 mt CO2e, which is far too low to exceed the 25,000 mt CO2e threshold as a result of these changes, and therefore will not experience an increase in burden.

None of the facilities that have off-ramped from subpart I were LCD or PV manufacturers, so no LCD or PV facilities would re-enter the GHGRP.

To determine whether any new facilities would become subject to subpart I, the annual manufacturing capacity at which MEMS facilities would become subject was calculated for the current rule, the proposed subpart I rule with current GWPs, and the proposed subpart I rule with AR5 GWPs. Capacity data from WFF was then analyzed to determine whether any facilities reported an annual capacity above any of these thresholds and would be expected to meet the applicability for subpart I if the proposed changes are finalized. The results of this WFF data analysis are shown in Table 4.3-7.

Table 4.3-7. Subpart I Applicability for Never Reported Facilities
Rule Version
MEMS Annual Manufacturing Capacity Threshold for Subpart I Applicability (m[2])
Number of Additional MEMS Facilities Above the Threshold[a]
Current Subpart I Rule, with Current Part 98 GWPs
1,075
--
Proposed Amendments to Subpart I Rule, with Current Part 98 GWPs
577
4
Proposed Subpart I Rule, with AR5 GWPs
561
4
a Compared to the number of MEMS facilities above the threshold defined by the current subpart I rule and current GWPs

The proposed subpart I changes to the current applicability emissions equation based on capacity are expected to result in up to four new MEMS facilities becoming subject to the rule, based on subpart I emissions alone. The combination of the proposed subpart I changes and AR5 GWPs is expected to produce the same result. Therefore, we conclude that the proposed adoption of AR5 GWPs is not expected to result in any additional MEMS facilities becoming subject to the GHGRP than would occur if only the proposed subpart I amendments were adopted. However, it should be noted that these estimates result from calculations based on capacity rather than actual gas consumption. Facilities may reach a different applicability determination if they choose to use the new calculation method based on gas consumption to estimate subpart I emissions, or if they have additional emissions that would be subject to other subparts (e.g., fossil-fuel combustion).

A previous analysis of the proposed subpart I changes concluded that subpart I emissions in terms of applicability would decrease on average for semiconductor, PV, and LCD fabs due to the subpart I GWP changes, based on the subpart I emission factors for these fabs. Therefore, no semiconductor, PV, or LCD manufacturing facilities are expected to become subject to subpart I for the first time as a result of the AR5 GWP changes.

Although some F-HTFs reported to subpart I would experience a GWP increase if AR6 GWPs were implemented, F-HTFs make up a small percentage of CO2e reported by each facility, so the AR6 GWP changes would not be significant enough to bring any of the previously off-ramped subpart I facilities back into the program. Additionally, since F-HTFs are not represented by any of the emission factors in the calculations to determine applicability under subpart I, we conclude that no new facilities would become subject to subpart I as a result of the AR6 GWP changes. 
As a result, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart I for new reporters.
 4.4 Subpart K
40 CFR part 98 subpart K (subpart K) requires reporting of greenhouse gas (GHG) emissions from ferroalloy production facilities using pyrometallurgical techniques to produce ferrochromium, ferromanganese, ferromolybdenum, ferronickel, ferrosilicon, ferrotitanium, ferrotungsten, ferrovanadium, silicomanganese, or silicon metal. Subpart K requires GHG emissions reporting for all facilities emitting greater than or equal to 25,000 mt CO2e per year in any single year. Additionally, pursuant to 40 CFR 98.2(i), reporting facilities are eligible to off-ramp from the GHGRP responsibilities given that they either report less than 25,000 mt CO2e for five consecutive years or report less than 15,000 mt CO2e for three consecutive years. The GHG emissions emitted during ferroalloy production are CO2 and CH4. 
For subpart K, the GWP changes shown in Table 4.4-1 are expected to affect reported emissions. 
Table 4.4-1. Applicable GWP Changes for Subpart K
                                    GHG[a]
                                  Current GWP
                                    AR5 GWP
                                    Change
CH4
                                      25
                                      28
                                   Increase
[a] N2O emissions are sometimes reported by ferroalloy facilities to subpart C although they are essentially 0% of total reported emissions when adding subpart C and K emissions each year.
The method used to evaluate reporter burden consists of three steps, as follows:
 Identify currently reporting facilities reporting less than 25,000 mt CO2e per year that are on track to off-ramp but who are expected to begin reporting above 25,000 mt CO2e per year again as a result of the changes in GWP.
 Identify previously off-ramped subpart K facilities and determine whether they will potentially re-enter the GHGRP as a result of the GWP changes.
 Identify facilities in the ferroalloy industry that are not currently subject to the GHGRP and assess their potential to begin reporting as a result of the GWP changes.
4.4.1 Current Reporters
To identify currently reporting subpart K facilities for which off-ramp eligibility may be affected, RY2020 GHGRP data were used to estimate the impacts of the GWP changes for each facility. There are currently nine facilities reporting to subpart K, and for each facility, the reported RY2020 GHG emissions (i.e., CO2, CH4, and N2O) were used to calculate a new total CO2e by applying the revised GWPs. The result was an estimation of CO2e emissions under the revised GWP for each subpart K facility, and an assessment of their off-ramp eligibility. Table 4.4-2 summarizes RY2020 data under the current and proposed GWPs.
Table 4.4-2. 2020 Subpart K Facility Total Emissions for Current and Proposed GWPs
                                  Facility ID
                 2020 Reporting: CO2e (mt) using Current GWPs
                 2020 Reporting: CO2e (mt) using Proposed GWPs
1006473
305,326
305,569
1003716
166,346
166,473
1007056
91,752
91,821
1005537
46,666
46,794
1005516
475,669
475,933
1002969
119,251
119,352
1004376
170,561
170,732
1009437
71,788
72,003
1013819
140,207
140,378

As shown, no facilities are on track to be eligible to off-ramp; thus, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart K for current reporters. It should also be noted that the reported CO2e using the proposed GWPs is expected to only increase by 0.11% on average per facility. This is because subpart K emissions are largely dominated by CO2. 
4.4.2 New Reporters
GHGRP data from RY2010 through RY2019 were used to identify previously off-ramped subpart K facilities that may potentially become subject to the GHGRP again. For each facility, the latest year's data for which the respective facility was reporting was used as proxy data to estimate present day CO2e emissions and applying the AR5 GWP values. For each facility, GHG emissions were summed at the facility level using the new GWPs, and if the emissions total more than 25,000 mt CO2e, it was assumed that the facility would re-enter the GHGRP and there would be a burden increase for the respective facility.
No subpart K facilities have previously off-ramped from the GHGRP. Therefore, there are zero facilities that could be pulled back into the program, and no possible burden from this assessment. 
To identify potential new GHGRP reporters within the ferroalloy industry, facility data from the United States Geological Survey (USGS) were used. A list of facilities was compiled to include all facilities listed in the silicon and ferroalloy USGS mineral yearbooks. These facilities were cross-referenced with the GHGRP data (by facility name and location) to determine which facilities are already reporting to the GHGRP. For the USGS facilities that are not already reporting to the GHGRP, it was determined whether they produce ferroalloy products that would make the facility subject to subpart K. 
For any potential new GHGRP reporter identified in the ferroalloy industry, publicly available Clean Air Act Title V permits were examined for production data. Title V permits were searched for each facility, but no production data were found. If production data had been available, emissions could have been estimated using either IPCC ferroalloy emission factors or Verified Carbon Standard ferroalloy emission factors.
Because no production data are available, national-level ferroalloy production data from the USGS Minerals Yearbook, by categories of "bulk ferroalloys" and "noble ferroalloys," were used. These data were used with conservative emission factors for each type to estimate national emissions, which were then divided by the number of facilities in each ferroalloy type. The result was a conservative estimate of the ferroalloy emissions for non-reporting facilities where the emissions estimated for each facility were multiplied by the average percentage change in emissions due to the GWPs for currently reported facilities. For facilities where emissions were estimated to be greater than or equal to 25,000 mt CO2e, it was assumed that the facilities would become subject to the GHGRP where an increase in facilities reporting to subpart K was a result of the GWP changes (i.e., an increased reporter burden). For facilities where emissions were estimated to be less than 25,000 mt CO2e, it was assumed there was no change in facilities reporting to subpart K given the GWP changes for facilities which were not previously reporting.
Between the two USGS industry segments, there were 17 available facilities. Of the 17 facilities, only four facilities were determined to be ferroalloy-producing facilities (as defined by 40 CFR 98.110) and not reporting to GHGRP. The four facilities identified are producers of ferromolybdenum, ferrotitanium, and ferrovanadium (all noble ferroalloys). For each of these four facilities, no production data were found in a search of Title V Operating Permits. 
Despite facility-level production data being unavailable for the four facilities, national-level production data for noble ferroalloys are available for the year 2018. This production value was disaggregated to the noble ferroalloy-producing facilities and multiplied by a conservative emission factor to estimate average emissions for noble ferroalloy-producing facilities. In 2018, 5,450 mt of noble ferroalloys were produced in the United States. Using a conservative emission factor of 11.04 mt CO2e per metric ton of product and assuming six facilities produce noble ferroalloys, it is estimated that noble ferroalloy-producing facilities emit 10,028 mt CO2e per year on average. As seen in Table 4.4-2, facilities are expected to increase 0.11% on average due to the GWP changes. An 0.11% increase of 10,028 mt is equal 10,039 mt; thus, it was concluded that no new facilities are expected to begin reporting to the GHGRP as a result of the proposed GWP changes.
 4.5 Subpart L
40 CFR part 98 subpart L (subpart L) requires reporting of GHG emissions from the production of fluorinated gases, which includes hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), SF6, nitrogen trifluoride (NF3), fluorinated ethers (hydrofluoroethers [HFEs] and hydrochlorofluoroethers [HCFEs]), and many others. Many fluorinated GHGs have high GWPs that result in high levels of CO2e from potentially small quantities of gases.
Reporting for subpart L is required if a facility emits 25,000 mt CO2e or more per year in combined emissions from subpart L and all other applicable source categories. For the purpose of comparing with the 25,000 mt CO2e threshold, subpart L emissions are determined on an uncontrolled basis (i.e., the emissions that would occur in absence of a destruction device). Facilities reporting under subpart L may stop reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2).
For subpart L, the AR5 GWP changes shown in Table 4.5-1 are expected to affect reported emissions.
Table 4.5-1. Applicable AR5 GWP Changes for Subpart L
GHG
Fluorinated GHG Group
Current GWP
AR5 GWP
Change
Sulfur hexafluoride
Fully fluorinated GHGs
22,800
23,500
                                                                       Increase
Trifluoromethyl sulfur pentafluoride
Fully fluorinated GHGs
17,700
17,400
                                                                       Decrease
Nitrogen trifluoride
Fully fluorinated GHGs
17,200
16,100
                                                                       Decrease
PFC-14 (Perfluoromethane)
Fully fluorinated GHGs
7,390
6,630
                                                                       Decrease
PFC-116 (Perfluoroethane)
Fully fluorinated GHGs
12,200
11,100
                                                                       Decrease
PFC-218 (Perfluoropropane)
Fully fluorinated GHGs
8,830
8,900
                                                                       Increase
PFC-3-1-10 (Perfluorobutane)
Fully fluorinated GHGs
8,860
9,200
                                                                       Increase
PFC-318 (Perfluorocyclobutane)
Fully fluorinated GHGs
10,300
9,540
                                                                       Decrease
PFC-4-1-12 (Perfluoropentane)
Fully fluorinated GHGs
9,160
8,550
                                                                       Decrease
PFC 5-1-14 (Perfluorohexane, FC-72)
Fully fluorinated GHGs
9,300
7,910
                                                                       Decrease
HFC-23
Saturated HFCs with two or fewer carbon-hydrogen bonds
14,800
12,400
                                                                       Decrease
HFC-32
Saturated HFCs with two or fewer carbon-hydrogen bonds
675
677
                                                                       Increase
HFC-125
Saturated HFCs with two or fewer carbon-hydrogen bonds
3,500
3,170
                                                                       Decrease
HFC-134a
Saturated HFCs with two or fewer carbon-hydrogen bonds
1,430
1,300
                                                                       Decrease
HFC-227ea
Saturated HFCs with two or fewer carbon-hydrogen bonds
3,220
3,350
                                                                       Increase
HFC-236fa
Saturated HFCs with two or fewer carbon-hydrogen bonds
9,810
8,060
                                                                       Decrease
HFC-43-10mee
Saturated HFCs with two or fewer carbon-hydrogen bonds
1,640
1,650
                                                                       Increase
HFC-143a
Saturated HFCs with three or more carbon-hydrogen bonds
4,470
4,800
                                                                       Increase
HFC-152a
Saturated HFCs with three or more carbon-hydrogen bonds
124
138
                                                                       Increase
HFC-161
Saturated HFCs with three or more carbon-hydrogen bonds
12
4
                                                                       Decrease
HFC-245fa
Saturated HFCs with three or more carbon-hydrogen bonds
1,030
858
                                                                       Decrease
HFC-365mfc
Saturated HFCs with three or more carbon-hydrogen bonds
794
804
                                                                       Increase
HFE-347mcc3 (HFE-7000)
Saturated HFEs and HCFEs with three or more carbon-hydrogen bonds
575
530
                                                                       Decrease
HFE-449s1 (HFE-7100) Chemical blend
Saturated HFEs and HCFEs with three or more carbon-hydrogen bonds
297
421
                                                                       Increase
Bis(trifluoromethyl)-methanol
Fluorinated Alcohols Other Than Fluorotelomer Alcohols
195
182
                                                                       Decrease

It is expected that emissions of any fluorinated GHGs that would be added to Table A-1 from AR6 are already reported under subpart L. Any gases that are not in the picklist of gases in the subpart L IVT form are manually entered by reporters as an "other" gas, and the reporter selects a standard fluorinated GHG group, with its default GWP, to best calculate CO2e based on the gas' chemical makeup. Addition of AR6 GWPs to Table A-1 would mean that the emissions from these gases would be calculated by their specific GWP in the future rather than using the default GWP of the fluorinated GHG groups they are assigned to by reporters.
For subpart L, the AR6 GWP changes shown in Table 4.5-2 are expected to affect reported emissions: 
Table 4.5-2. Applicable AR6 GWP Changes for Subpart L
GHG
Current Assigned Fluorinated GHG Group
AR6 Fluorinated GHG Group
Current
Fluorinated GHG Group GWP
AR6 GWP
Change
Heptacosafluorotributyl-amine
Fully fluorinated GHGs
Fully fluorinated GHGs
10,000
8,490
Decrease
Perfluorotetrahydrofuran
Fully fluorinated GHGs
Fully fluorinated GHGs
10,000
13,900
Increase
Perfluorotripropylamine
Fully fluorinated GHGs
Fully fluorinated GHGs
10,000
9,030
Decrease
HFE-7300
Saturated HFEs and HCFEs with three or more carbon-hydrogen bonds
Halogenated alcohols, ethers, furans, aldehydes and ketones
270
405
Increase
Heptafluoroisobutyronitrile
Other fluorinated GHGs
Other fluorinated GHGs
2,000
2,750
Increase

4.5.1 Current Reporters
The first step (step 1) of this analysis was to recalculate RY2020 facility emissions for all subpart L facilities to evaluate the changes resulting from the anticipated GWP changes. Emissions of named fluorinated GHGs in production and transformation (P/T) processes at the facility level, container venting, and destruction of previously produced gases were re-estimated using the new GWPs. In addition, while emissions from all gases are calculated using individual gas GWPs when available, some emissions are then displayed in reports by fluorinated GHG group rather than by individual gas. For facilities with any P/T emissions at the facility level reported by GHG group, the emissions reported by individual gas were subtracted from each group, and the GWP change of the remaining emissions of each group that is also listed in Table 4.5-1 were calculated in two ways: (1) assuming 100% of the emissions reported by GHG group were from the gas within the group with the largest GWP increase, and (2) assuming 100% of the emissions reported by GHG group were from the gas within the group with the largest GWP decrease. This established a "worst-case" (largest emissions) and a "best-case" (lowest emissions) set of revised emissions for these GHG groups to determine the range of the total subpart L emissions of each facility resulting from the anticipated GWP changes. The average change in reported CO2e emissions for GHGRP facilities was then calculated.
Step 1 determined that subpart L facilities had an average decrease in emissions, and any subpart L facilities with subpart L emissions below 25,000 mt CO2e were then examined to determine whether any facilities would become eligible to off-ramp based on their total facility emissions. This required estimating emissions changes from GWP changes in other subparts that also report to these L facilities. As of RY2020, one subpart L facility had become eligible to off-ramp, and we conclude that this facility would still be eligible to off-ramp if the new GWPs were applied. We conclude that no other facilities would become eligible to begin off-ramping due to the anticipated GWP changes.
The calculated subpart L emissions for each facility are shown in Table 4.5-3.
Table 4.5-3. Recalculated Subpart L Emissions from All Facilities
Facility ID
Subpart L Emissions (mt CO2e)

With Current GWPs
With New GWPs (max)
With New GWPs (min)
1004206
1,954
2,660
1,940
1004725
3,990
4,287
4,024
1000625
7,253
10,845
2,464
1004836
16,664
17,023
16,641
1002618
18,329
19,045
17,833
1006145
18,464
19,594
18,410
1006675
19,673
20,095
16,408
1006314
51,401
47,190
45,736
1003890
106,343
110,403
110,403
1006070
418,939
393,771
393,672
1005062
438,344
437,666
437,540
1002176
503,412
479,826
479,696
1005721
546,247
489,671
489,606
1006665
628,466
587,317
577,263
1005202
848,010
790,723
790,723

Seven facilities that have subpart L emissions below 25,000 mt CO2e considering both sets of GWPs. We then examined the total facility emissions for these seven facilities to determine whether they are potentially eligible to off-ramp. Each of these facilities also reported emissions of carbon dioxide under subpart C. Carbon dioxide has a GWP of 1 which is not impacted by the anticipated GWP changes. Any facility with carbon dioxide emissions greater than 25,000 mt CO2e from subpart C would not become eligible to off-ramp as a result of the GWP changes. Total facility emissions and CO2e emissions for these seven facilities are shown in Table 4.5-4.
Table 4.5-4. Emissions from Potential Off-Ramping Facilities (Using Current GWPs)
Facility ID
Subpart L Emissions 
(mt CO2e)
Total Facility Emissions (mt CO2e) 
Carbon Dioxide Emissions (mt CO2e)
1004206
1,954
44,017
42,017
1004725
3,990
4,004
0
1000625
7,253
32,155
24,879
1004836
16,664
49,540
32,805
1002618
18,329
32,761
1,014
1006145
18,464
55,587
37,073
1006675
19,673
51,627
31,923

Based on these calculated emissions, Facility 1004725 is well below the lower 15,000 mt CO2e threshold to off-ramp and has been for 3 years as of RY2020. Applying the new GWPs to their emissions caused a slight increase, which does not impact the reporting burden of this facility.
Facilities 1000625 and 1002618 had total facility emissions nearing the 25,000 mt CO2e threshold to off-ramp, and also had carbon dioxide emissions below 25,000 mt CO2e. For these facilities, the emissions of other reported subparts were then recalculated using the new GWPs to determine whether they would drop below the 25,000 mt CO2e threshold (Table 4.5-5).
Table 4.5-5. Emissions from Potential Off-Ramping Facilities in mt CO2e (Using New GWPs)
Facility ID
All Subpart L Gases (min)
Carbon Dioxide
Methane
Nitrous Oxide
Total
1000625
2,464
24,879
13
12
27,368
1002618
17,833
1,014
16,292
2
35,141

Even when using the minimum estimate of subpart L emissions, the total facility emissions of these two facilities are still greater than the 25,000 mt CO2e threshold to off-ramp when the new GWPs are applied. 
As a result, there is no change to the number of affected facilities due to the proposed revised AR5 and AR6 GWPs for subpart L for current reporters.
4.5.2 New Reporters
Step 1 of this analysis (described in Section 4.5.1) determined that subpart L facilities had an average decrease in emissions, so we conclude that no new reporters would become subject to this subpart and none of the reporters that have previously off-ramped would be brought back into the GHGRP due to the revised GWPs. As a result, there is no change to the number of affected facilities due to the proposed revised AR5 and AR6 GWPs for subpart L for new reporters.
 4.6 Subpart O
40 CFR part 98 subpart O (subpart O) requires reporting of GHG emissions from HCFC-22 (chlorodifluoromethane) production processes and for HFC-23 (trifluoromethane) destruction processes. The use of HCFC-22 as a refrigerant was phased out in 2020 due to its ozone-depleting effects, but it continues to be produced for feedstock use (i.e., transformation). The only emissions reported under subpart O are HFC-23 emissions.
Reporting for subpart O is required for all facilities with HCFC-22 production processes and for facilities with HFC-23 destruction processes that destroy more than 2.14 mt of HFC-23 per year. Facilities reporting under subpart O may discontinue reporting if the facility-wide CO2e emissions fall below the levels specified in the off-ramp provisions in §98.2(i).
For subpart O, the GWP change shown in Table 4.6-1 is expected to affect reported emissions. 
               Table 4.6-1. Applicable GWP Change for Subpart O
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
HFC-23
14,800
12,400
Decrease

4.6.1 Current Reporters
There were five subpart O facilities in RY2020, two of which reported zero emissions under subpart O. Because subpart O emissions will decrease under the AR5 GWPs and there are only five facilities, we estimated the expected facility-level emissions changes for all five facilities to see if any would drop below 25,000 mt CO2e under the new AR5 GWP. No new subpart O facilities will be required to report to the GHGRP as a result of the AR5 GWP changes because the GWP is decreasing.
As shown in Table 4.6-2, the only subpart O facility that is currently near the 25,000 mt CO2e threshold is facility 1013278, which had total emissions of 32,870 mt CO2e in RY2020. Over 99% of this facility's emissions are from CO2 reported under subpart C. Therefore, no impact to their reporting burden is expected from the AR5 GWP changes.
    Table 4.6-2. Total Facility Emissions for Subpart O Reporters (RY2020)
                                  Facility ID
                               Subparts Reported
                Subpart O Emissions with Current GWP 
(mt CO2e)
                       Subpart O Emissions with AR5 GWP
                                   (mt CO2e)
                   Change in Calculated Subpart O Emissions
                                   (mt CO2e)
                     Total Nonbiogenic Facility Emissions
                                 (mt CO2e) [a]
1004133
C, O, TT
2,096,139
1,756,224
-339,914
2,118,699
1005062
C, L, O
4,924
4,125
-798
483,822
1006070
C, L, O
4,423
3,706
-717
528,959
1002176
C, L, O
<1
<1
 - 
753,562
1013278
C, O
<1
<1
 - 
32,870
[a] As reported, using current GWPs.
Although facilities 1004133, 1005062, 1006070, and 1002176 all have projected subpart O emissions decreases, their total facility emissions are still much higher than the 25,000 mt CO2e threshold. As such, their applicability under the GHGRP will not be impacted by the proposed AR5 GWP changes.
In conclusion, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart O.
 4.7 Subpart T
40 CFR part 98, subpart T (subpart T) is a direct emitter subpart and requires reporting of GHG emissions from magnesium production facilities that emit greater than 25,000 mt CO2e per year in any single year. Subpart T applies to primary and secondary magnesium production plants and facilities with any type of magnesium casting operations. The GHG emissions from this source category include releases of the following gases used as cover or carrier gases in magnesium production or processing: SF6, HFC-134a, CO2, and perfluoro (2-methyl-3-pentanone) (also called FK-5-1-12 or Novec(TM)). Additionally, some reporters under subpart T report general stationary fuel combustion emissions of CO2, N2O, and CH4 under subpart C of the GHGRP. Facilities are allowed to stop reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2).
For subpart T, the GWP changes shown in Table 4.7-1 are expected to affect reported emissions. 
               Table 4.7-1. Applicable GWP Changes for Subpart T
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
SF6
22,800
23,500
Increase
HFC-134a
1,430
1,300
Decrease
FK 5-1-12, perfluoro(2-methyl-3-pentanone)
0.1
<1
No Change

Table 4.7-2 presents the cover and carrier gas use reported in the most recent three reporting years under subpart T. Minimum and maximum values listed are on a per-facility basis.
     Table 4.7-2. Subpart T Cover and Carrier Gas GHGs (RY2018  -  RY2020)
                                      GHG
                      Number of Facilities Reporting Use
                           Minimum Use Reported
[mt]
                           Maximum Use Reported
[mt]
CO2
5
12.27
912.1
SF6
11
0.0268
10.79
HFC-134a
3
0.38
43.544
FK 5-1-12
1
0.072
0.072

4.7.1 Current Reporters
Reporters may use multiple cover and carrier gases; therefore, review was conducted on both CO2e increases (from SF6) and decreases (from HFC-134a) to determine any change in burden associated with the revised GWP values. Annual emissions on a per GHG basis were obtained from Envirofacts on March 23, 2022. The total GHG emissions from RY2020 for each facility were calculated using the revised AR5 GWP values shown in Table 4.7-1. The impact of the proposed changes to N2O and CH4 GWPs on the CO2e calculated and reported under subpart C are negligible. Of the 14 subpart T facilities that have reported to the GHGRP, only 9 reported emissions from fossil-fuel combustion units. Eight of these facilities burn only natural gas and one facility burned natural gas and No.2 fuel oil. The proposed GWP changes decrease the overall CO2e for natural gas combustion and No.2 fuel oil by 3 x 10[-4] kg/MMBtu and 1.08 x 10[-2] kg/MMBtu, respectively. Also, given the low magnitude of the GWP for FK 5-1-12 and that only one reporter in the last three reporting years has indicated usage of the gas (which was less than 0.1 mt) and this reporter also used SF6, it was assumed the change to the GWP for FK 5-1-12 would have negligible impact.
The CO2e calculated using the revised GWP values was then compared to the CO2e emissions reported by the facility in their RY2020 report to determine if the CO2e for any facility decreased below the 25,000 mt CO2e threshold. Additionally, review was conducted to determine if any resultant CO2e change would impact the timeline for a facility to off-ramp from reporting or result in a facility that had off-ramped following RY2021 or RY2022 becoming subject to reporting in RY2023, if the AR5 GWP values became effective beginning in RY2023. 
Table 4.7-3 presents the total reported emissions (from all GHGRP subparts) for reporters that reported under GHGRP subpart T. Of the nine current subpart T reporters, six also reported emissions under subpart C  -  General Stationary Fuel Combustion Sources. Reporters to subpart T have not reported to any other subparts besides subparts C and T. As noted above, changes to CO2e reported to subpart C are negligible for the purposes of this evaluation. For current reporters, the updated GWP values resulted in changes to calculated CO2e emissions ranging from -1.4% to 3.1%, with eight facilities showing increased emissions.
There is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart T if the AR5 GWP values are adopted beginning in RY2023. The single facility that would report lower CO2e using the AR5 GWP values reports CO2e emissions over 10 times the reporting threshold, so the 1.4% decrease in CO2e is immaterial to the facility's status as a subpart T reporter. The other eight reporters that showed increases in CO2e from recalculation using the AR5 GWP values were evaluated to determine if any impact on off-ramping is anticipated, either through delaying when a facility would qualify or by bringing a facility back over the reporting threshold. Three of these facilities reported emissions under the 25,000 mt threshold in RY2020. If future reporting year emissions are equal to those reported in RY2020 or any of the prior four reporting years, these facilities would qualify to off-ramp at the same time regardless of change in GWP values (i.e., the GWP change would not cause any RY2016 through RY2020 reported CO2e to increase to levels above either the 15,000 or 25,000 mt thresholds for these facilities.)
In evaluating the potential burden impact of GWP changes, the year-over-year changes to reported CO2e emissions for subpart T reporters typically show a greater magnitude of change than the changes that would be caused by adoption of the AR5 GWP values. For RY2020, the absolute magnitude of yearly change in reported CO2e emissions on an individual reporter basis ranged from 0.19% to 50% with an average of all subpart reporters of 23%. Prior reporting years show similarly high average changes in reported emissions, ranging from 11% in RY2015 to 52% in RY2019. This suggests that changes to reporting under subpart T following adoption of the AR5 GWP values are likely to be driven more by operational changes than by revision to the GWP values, which have a maximum magnitude of impact of 10%. 
      Table 4.7-3. Emission Changes from Subpart T Reporters Based on AR5 GWP Changes
                                  Facility ID
                       RY2020 CO2e  -  As Reported
[mt]
                         RY2020 CO2e  -  AR5 GWP
[mt]
                                  Change
[mt]
                                Percent Change
1000030
310,631
306,327
-4,304
-1.4%
1002358
20,601
21,090
+489
+2.4%
1009864
110,875
114,107
+3,232
+2.9%
1009927
15,192
15,658
+466
+3.1%
1010145
70,170
70,966
+796
+1.1%
1010185
246,012
253,565
+7,553
+3.1%
1012081
44,186
45,543
+1,357
+3.1%
1013263
27,321
27,759
+438
+1.6%
1013267
9,134
9,414
+280
+3.1%
4.7.2 New Reporters
An increase in the GWP for SF6 has the potential to bring previously off-ramped reporters back above the 25,000 mt CO2e threshold. Review was conducted based upon the frozen dataset to determine whether previously reporting facilities had off-ramped due to decreased emissions or from facility closure. For facilities that had ceased reporting due to emissions decreasing below the off-ramp thresholds, their reported CO2e was recalculated using the revised AR5 GWP values to determine if the facility would be expected to report again. Facilities that off-ramp are required to recommence reporting if the facility-wide CO2e exceeds 25,000 mt in any single calendar year.
Table 4.7-4 presents the total reported emissions (from all GHGRP subparts) for the three facilities that qualified to exit the program pursuant to the off-ramp provisions in 40 CFR 98.2(i) in the last year that they reported to the GHGRP. Utilizing the same GHG quantities as when they last reported to the GHGRP, the CO2e calculated using the AR5 GWP values are higher for all three facilities. However, the AR5 GWP values would not result in the CO2e exceeding the 25,000 mt CO2e threshold that would require any of these facilities to commence reporting in RY2023. 
        Table 4.7-4. Impact on CO2e Emissions for Off-Ramped Reporters
                                 Facility Name
                                   GHGRP ID
                                Most Recent RY
                           CO2e  -  As Reported
[mt]
                             CO2e  -  AR5 GWP
[mt]
Shiloh Clarksville
1012966
2018
9,514
9,807
Spartan Light Metal Products
1010676
2018
7,866
8,048
Neaton Auto Products Manufacturing, Inc.
1009879
2016
11,648
11,976

To determine whether the increase in GWP for SF6 would result in the entry of additional facilities that are not current or previous reporters to the GHGRP, the information supporting the 2010 GHGRP Rule was reviewed as well as the 2013 GHGRP Revision Assessment. These assessments of the magnesium production sector provide data regarding the number of nationwide facilities in the sector as well as their expected magnitude of emissions.
Additional review was conducted to identify current counts of the population of magnesium production facilities in the United States. This included review of the membership of an industry trade group, the International Magnesium Association (IMA), and statistics on magnesium production available from the USGS. These facility counts were then compared to the population of current and past reporters to subpart T to identify any potential new reporters.
The threshold analysis for the magnesium production category for the original 2010 GHGRP rule identified 13 facilities within the source category. The 2013 GHGRP Revision Assessment reviewed information from the EPA's voluntary SF6 Emission Reduction Partnership for the Magnesium Industry as an additional source of information on the number of expected facilities in the magnesium production source category. Based on the 2010 SF6 Partnership data reviewed, an updated total of 16 facilities were identified, of which 11 reported using SF6 as a cover gas. Since reporting for subpart T began in 2011, 14 unique facilities have reported to the GHGRP. This suggests that the counts estimated during the original rulemaking and the 2013 GHGRP Revision Assessment provided a high degree of coverage of the population of potential reporters.
Additional information from the IMA and the USGS were reviewed to identify magnesium production facilities that have not reported to the GHGRP. The IMA is a trade group with membership available to "any corporation producing, manufacturing, fabricating, using or marketing metallic magnesium or products of metallic magnesium in their regular business or, in the opinion of the Board of Directors, directly associated with the industry." Review of IMA membership data identified 12 corporate members based in the United States. Of these, five corporations operate facilities that are currently reporters to subpart T. The web pages for the remaining seven corporate members were evaluated to assess if their operations potentially meet the source category definition of subpart T at 40 CFR 98.200. Two of the non-reporting corporations (operating a total of 20 facilities) engage in die-casting, two corporations (operating a total of eight facilities) in the production of die-casting equipment, one corporation (operating a single facility) in the production of extruded magnesium alloys, and one corporation (operating two facilities) in the magnesium fluxes, melting, and refining industry segment. Information was not available for one of the corporations. The IMA member operations were then mapped to either primary, secondary, die- and sand-casting, or other processes (per the requirements of 40 CFR 98.206(b)) using information available on their corporate website. Reporting to the GHGRP is at the facility level, so as a conservative assumption, each of the locations identified through IMA member's corporate web pages were assumed to utilize magnesium processes within the source category definition at 40 CFR 98.200. This assumption likely overstates the potential population of facilities, as some of the plant locations are likely administrative, sales, and other ancillary operations that do not engage in magnesium production operations. Table 4.7-5 presents the count of facilities operated by IMA corporate members that do not currently report emissions to the GHGRP, by subpart T operation classification category.
    Table 4.7-5. IMA Corporate Members That Have Not Reported to Subpart T
                           Subpart T Classification
               Potential Additional Reporters in IMA Membership
       Description of Operations
(Based on Review of Corporate Website)
Primary Production
0
N/A
Secondary Production
0
N/A
Die- and Sand-Casting
20
Magnesium die-casting
Other
3
Extruded magnesium alloy production
Magnesium fluxes, melting, and refining
Not Part of Source Category
8
Die-casting equipment manufacturers

As shown in Table 4.7-5, the IMA membership data did not identify any potential subpart T reporters with primary or secondary magnesium production operations. To verify this conclusion, USGS data for primary and secondary production of magnesium were reviewed. The USGS's Mineral Commodity Summaries for 2011 through 2022 indicate that primary magnesium production has occurred at a single facility in the United States. This facility reported subpart T data continuously since GHGRP reporting began in RY2011 (GHGRP ID 1000030). The USGS Mineral Commodity Summaries do not provide a count for the number of secondary magnesium production facilities but do indicate that estimated employment in the magnesium metal industry has held constant at 400 employees since 2011. Additionally, USGS data shows that secondary magnesium production in the United States has declined from 112 tons in 2017 to 100 tons in 2020. The flat level of employment and production in the magnesium metal industry estimated by the USGS supports the results of our IMA membership review that there are no primary or secondary magnesium production facilities that are not already reporting to the GHGRP.
Based upon the review of IMA corporate membership, as many as 20 facilities may be engaged in magnesium die-casting that have not previously emitted above the 25,000 mt CO2e threshold and may be impacted by adoption of revised GWP values. Since these facilities have never reported to the GHGRP, only the potential for increased burden related to the GWP for SF6 needs to be considered. For a facility exclusively using SF6 as a cover gas (the most likely scenario to experience increased burden), the revised GWP would result in a 3% increase to calculated CO2e. Table 4.7-6 presents the number of reporters to subpart T in each classification category for RY2018 - 2020. As shown in Table 4.7-6, existing reporters in the die- and sand-casting magnesium industry segment have significantly lower emissions than primary and secondary facilities. 
              Table 4.7-6. Subpart T Reporters by Reporting Year
                                Reporting Year
                              Number of Reporters
                           Total CO2e Emissions
[mt]
                          Average CO2e
[mt/reporter]
                                SF6 Usage 
[mt]
                             HFC-134a Usage 
[mt]
                                       
                                       
                                       
                                       
                                     Range
                                     Avg.
                                     Range
                                     Avg.
Primary Production
2018
1
 397,764 
 397,764 
0
43.5
2019
1
 384,492 
 384,492 
0
38.6
2020
1
 310,631 
 310,631 
0
33.1
Secondary Production
2018
3
 433,904 
 144,635 
0  -  10.4
6.0
0  -  11.6
3.9
2019
2
 316,041 
 158,020 
2.4  -  10.8
6.6
0  -  7.6
3.8
2020
2
 316,182 
 158,091 
2.5  -  10.8
6.6
0  -  7.3
3.6
Die- and Sand-Casting
2018
8
 347,287 
 43,411 
0.3  -  5.7
1.7
0
0
2019
6
 282,561 
 47,094 
0.5  -  4.6
1.8
0  -  0.4
0.1
2020
6
 227,309 
 37,885 
0.4  -  4.6
1.5
0
0

Figure 4.7-1 presents the average SF6 emissions reported per facility in the die- and sand-casting industry segment from 2011 through 2020. The average SF6 emissions per reporter in this segment declined significantly from 3.6 mt in 2011 to 1.7 mt in 2013 and has ranged between 1.4 and 1.8 mt in subsequent years. Over this period, three reporters in the segment reported total facility-level emissions less than 25,000 mt CO2e per year for five consecutive years and qualified to off-ramp from reporting. Since Figure 4.7-1 is based only upon data reported to subpart T, it may overstate the average SF6 use for the industry segment as facilities that utilize less than 1.1 mt of SF6 would only be represented if usage of other cover or carrier gases caused them to meet the reporting threshold. 
      Figure 4.7-1. Die- and Sand-Casting Average SF6 Usage per Reporter

[1] One reporter (GHGRP ID 1012966) reported emissions for RY2017 and RY2018 despite not exceeding the 25,000 mt reporting threshold. The "Adjusted Average" represents SF6 emissions per reporter if these data are excluded.

For adoption of the AR5 GWP values to be the sole cause of increased reporting burden for a magnesium die-casting facility, the facility would have to have operations that emit within 3% of the 25,000 mt CO2e threshold (using current GWP values), but never have emitted over 25,000 mt CO2e in any prior reporting year. If a facility had emitted over 25,000 mt CO2e in any prior year, the facility should be already part of the population assessed in Table 4.7-4 as a previous reporter. Existing reporters in the die-casting industry segment exhibit significant variability in year-to-year reported emissions, as summarized in Table 4.7-7. Given the annual variability observed for other reporters in this segment, it is unlikely that there are magnesium die-casters utilizing SF6 that emitted within 3% of the 25,000 mt CO2e threshold but have never exceeded the reporting threshold in any prior reporting year. Additionally, it is possible that some of the 20 magnesium die-casters we identified as possible new reporters utilize, either exclusively or in substantial proportion compared to SF6, cover gases that have significantly lower GWP values (e.g., HFC-134a, FK-5-1-12), or use SO2. Similarly, facilities may use carrier gases, such as nitrogen and dry air, instead of CO2. Given the observed high variability in annual SF6 emissions within the magnesium die-casting segment, as well as the relatively low potential magnitude of impact of the revised AR5 GWP values, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart T for new reporters.
Table 4.7-7. Year-over-Year Change in Reported Emissions for Individual Die- and Sand-Casting Facilities
                                Reporting Year
                   Average Reported Magnitude of Change [a]
                     Minimum Reported Change in Emissions
                     Maximum Reported Change in Emissions
2012
38%
5%
86%
2013
26%
2%
100%
2014
27%
3%
65%
2015
11%
1%
36%
2016
37%
4%
100%
2017
34%
0%
100%
2018
33%
1%
120%
2019
52%
3%
100%
2020
23%
0.19%
50%
[a] Magnitude of change calculated on an individual reporter basis as | (Prior Year Emissions)  -  (Reporting Year Emissions) | / (Prior Year Emissions); Average calculated as the sum of individual magnitudes of change divided by the number of reporters in the segment for the specified reporting year.
 4.8 Subpart V
40 CFR part 98 subpart V (subpart V) applies to all nitric acid production facilities in the United States that produce nitric acid of any strength, beginning in RY2010. Nitric acid production facilities only report N2O emissions to subpart V. No CO2 or CH4 emissions result from the production of nitric acid. There is no initial reporting threshold for this subpart. Through RY2020, no subpart V facilities have stopped reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2). However, seven facilities since RY2010 have stopped producing nitric acid.
For subpart V, the GWP change shown in Table 4.8-1 is expected to affect reported emissions.
Table 4.8-1. Applicable GWP Change for Subpart V
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
N2O
298
265
Decrease
4.8.1 Current Reporters
The methodology used for this analysis was to evaluate how the change in GWPs would affect a facility subject to subpart V that is near the upper off-ramp threshold of 25,000 mt CO2e. For this analysis, "near the upper threshold" was defined as +-20% of 25,000 mt CO2e (20,000 to 30,000 mt CO2e) to allow for variation in emissions from year to year. Table 4.8-2 shows the five lowest-emitting facilities that were subject to subpart V in RY2020 along with the applicable subparts and the RY2020 total facility emissions.
Table 4.8-2. RY2020 Total Emissions from the Five Smallest Facilities Subject to Subpart V 
                                  Facility ID
                              Applicable Subparts
                     RY2020 Emissions (CO2e) 
Current GWP
1003636
C, U, V
19,138
1005506
C, V
26,212
1002188
C, V
48,477 
1002263
C, V
118,437 
1012789
C, G, V
123,210

As shown in Table 4.8-2, only one facility, 1005506, had facility-level emissions between 20,000 and 30,000 mt CO2e for RY2020. The next step in this analysis was to review facility-level emissions for facility 1005506 from RY2016 to RY2020, using the current GWPs to demonstrate overall emission trends for the past five years. Emissions data from RY2016 to RY2020 for facility 1005506 are shown in Table 4.8-3.
Table 4.8-3. Total Emissions from RY2016-RY2020 For Facility 1005506 Using Current GWPs
                                  Facility ID
                              Applicable Subparts
                   Yearly Emissions (CO2e using current GWP)
                                       
                                       
                                     2016
                                     2017
                                     2018
                                     2019
                                     2020
1005506
C, V
  7,375 
5,251 
 5,436 
17,893 
26,212 

As shown in Table 4.8-3, facility 1005506 could have off-ramped after RY2018 with three consecutive years lower than 15,000 mt CO2e. However, emissions in RY2019 and RY2020 were above 15,000 mt CO2e and 25,000 mt CO2e, respectively, meaning that the facility was no longer eligible to stop reporting to the GHGRP after RY2019 or after RY2020. Note that emissions from facility 1005506 have been increasing since RY2017.
Table 4.8-4 shows facility-level emissions for subpart V facility 1005506 in RY2020 using current GWPs and the new AR5 GWPs. Note that all but a small amount of the N2O total emissions originates from the process emissions reported under subpart V. 
Table 4.8-4. RY2020 Facility-Level Emissions for Facility 1005506
                                  Facility ID
                              Applicable Subparts
                                   CO2 (mt)
                                   CH4 (mt)
                                   N2O (mt)
                            Total Emissions (CO2e)
                                 Current GWPs
                            Total Emissions (CO2e)
                                   AR5 GWPs
1005506
C, V
816
0.02
85
26,212
23,400

As shown in Table 4.8-4, facility 1005506 could potentially off-ramp if RY2021 and RY2022 emissions are consistent with emissions reported between RY2016 and RY2019. However, facility 1005506 is unlikely to off-ramp if RY2021 and RY2022 emissions are consistent with emissions reported for RY2020. Therefore, whether or not facility 1005506 will stop reporting to the GHGRP as a result of the changes in GWPs is highly dependent on the facility's actual emissions after RY2020 and when the AR5 GWP change takes effect. To be conservative, one additional facility is expected to report to subpart V as a result of the proposed revised AR5 GWPs. 
 4.9 Subpart W
40 CFR part 98, subpart W (subpart W) requires reporting of GHG emissions from petroleum and natural gas systems. Subpart W reporters currently report by industry segment and emission source. There are 10 different industry segments: Offshore Petroleum and Natural Gas Production, Onshore Petroleum and Natural Gas Production, Onshore Petroleum and Natural Gas Gathering and Boosting, Onshore Natural Gas Processing, Onshore Natural Gas Transmission Compression, Underground Natural Gas Storage, Liquefied Natural Gas (LNG) Storage, Liquefied Natural Gas Import and Export Equipment, Natural Gas Distribution, and Onshore Natural Gas Transmission Pipeline. There are 20 different emission sources with varying applicability based on the industry segment reported. The GHGs emitted from these emission source types are CO2, CH4 and N2O.
Currently, a petroleum and natural gas system facility is required to begin reporting if it is estimated to emit 25,000 mt CO2e or more in combined emissions from subpart W and all other applicable source categories in a calendar year. Facilities that are subject to reporting under subpart W may stop reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2).
For the impacts of the proposed AR5 GWP changes, the facility-level emissions being compared to the subpart W direct emitter threshold (25,000 mt CO2e) take into account the quantifiable emissions changes due to the proposed AR5 GWP changes. The number of new reporters identified are those that exceed the direct emitter threshold due to the proposed GWP changes only.
Table 4.9-1. Applicable GWP Changes for Subpart W
GHG
Current GWP
AR5 GWP
Change
CH4
25
28
Increase
N2O
298
265
Decrease

4.9.1 Current Reporters
The emissions from current subpart W reporters were recalculated using the proposed GWPs to determine their ability to off-ramp. As shown in Table 4.9-1, the GWP for CH4 is being increased from 25 to 28 while the GWP for N2O is being decreased from 298 to 265. On average, less than 1% of the annual emissions reported to subpart W are from N2O on a CO2e basis. Therefore, it is expected that the decrease in the GWP for N2O will be more than offset by the increase in the GWP for CH4 for all current subpart W reporters. For the purposes of estimating impacts from GWP changes for subpart W, we assumed that there will be no potential for off-ramping expected due to the AR5 GWP changes.
4.9.2 New Reporters
To determine the number of new subpart W reporters, both reporters that had previously met the off-ramp requirements to exit the GHGRP and those that never exceeded the reporting threshold were reviewed for potential re-entry or entry into the GHGRP. 
4.9.2.1.	Analyses of Previously Off-Ramped Facilities
Subpart W contains 10 industry segments defined in 40 CFR 98.230. For the purposes of quantitatively estimating the effect of the proposed AR5 GWP changes at the industry segment level, we corrected the RY2020 GHGRP emissions from the known subpart W facilities using the proposed AR5 GWP changes to estimate the average percent increase in emissions for each industry segment. The GHGRP data used in these analyses are taken from the data published by the EPA in the fall of 2021.
Table 4.9-2 provides a summary of the percent changes by industry segment due to the proposed AR5 GWP changes. The results presented are limited to current reporters and include subpart C combustion emissions, where applicable.
Table 4.9-2. Industry Segment Level Percent Change of the Emissions Estimated Using AR5 GWPs
Industry Segment
% Change
Offshore Petroleum and Natural Gas Production
8
Onshore Petroleum and Natural Gas Production
5
Onshore Natural Gas Processing
1
Onshore Natural Gas Transmission Compression
1
Underground Natural Gas Storage
3
LNG Storage
1
LNG Import / Export
0
Natural Gas Distribution 
12
Onshore Petroleum and Natural Gas Gathering and Boosting
3
Onshore Natural Gas Transmission Pipeline
12
All Segments Combined 
3

As stated earlier, any facility that has previously met the emission requirements to off-ramp is required to begin reporting again if their facility-wide emissions exceed 25,000 mt CO2e for any year thereafter. A total of 79 subpart W facilities have been eligible to off-ramp from the program to date. To determine how many of those facilities could be expected to report to subpart W again after the proposed AR5 GWP changes, we used the percent increase by industry segment and applied to the last known GHGRP reported emissions from each of the off-ramped facilities.
Using the information in Table 4.9-2, we determined that the highest percent change in RY2020 emissions resulting from the proposed AR5 GWP changes was 12%. Therefore, the lowest emissions for which the proposed AR5 GWP changes could result in off-ramped facilities emitting greater than 25,000 mt CO2e was 22,321 mt CO2e. As shown in Table 4.9-3, only 4 of the 79 facilities had emissions greater than 22,000 mt CO2e. The table shows each of the four facilities, the last known GHGRP reported emissions, the industry segment, and the expected emissions after the proposed AR5 GWP changes. 
As shown in Table 4.9-3, two off-ramped facilities in the Offshore Petroleum and Natural Gas Production industry segment are expected to have facility-wide emissions that exceed 25,000 mt CO2e as a result of the AR5 GWP changes. The other two facilities in Table 4.9-3 with emissions greater than 22,000 mt CO2e were in the Onshore Natural Gas Transmission Compression industry segment, which is only expected to have a 1% increase in emissions due to the proposed AR5 GWP changes, so the expected emissions for those two facilities would not exceed the 25,000 mt CO2e reporting threshold. 
Two previously off-ramped facilities are expected to become subject to subpart W as a result of the proposed AR5 GWP changes.
Table 4.9-3. Off-Ramped Subpart W Facilities
Facility ID
Total Emissions from Most Recent RY (mt CO2e)
Industry Segment
Expected Emissions After GWP change
1007560
24,860 [2018]
Offshore Petroleum and Natural Gas Production
26,849
1009017
22,441 [2018]
Onshore Natural Gas Transmission Compression
22,665
1008941
22,128 [2018]
Onshore Natural Gas Transmission Compression
22,349
1009914
23,847 [2018]
Offshore Petroleum and Natural Gas Production
25,755

4.9.2.2 Analyses of Non-Reporters Entering the GHGRP
To determine the number of potential new subpart W reporters in each industry segment as a result of the proposed AR5 GWP amendments, we first estimated facility-level emissions for each industry segment for facilities that do not currently report (hereafter referred to as "non-subpart W reporters"). A non-subpart W reporter is counted as a new reporter for the purposes of assessing impacts if the facility-level emission estimate after considering the proposed AR5 GWP changes exceeds the 25,000 mt CO2e direct emitter threshold for subpart W. As noted previously, we have assumed that any facility currently reporting will continue to do so after the implementation of the proposed AR5 GWP amendments. 
The facility-level emission estimates for each industry segment were developed by extrapolating subpart W data and/or by using data from publicly available external sources (e.g., U.S. Energy Information Administration). The extent to which we used extrapolated subpart W data and/or external data sources as well as the level of detail in the facility-level estimates is highly variable and specific to each industry segment based on the availability and granularity of existing data.
Industry Segment 1: Offshore Petroleum and Natural Gas Production
The number of facilities and mass of emissions for the Offshore Petroleum and Natural Gas Production (Offshore Production) industry segment were estimated by cross-walking the RY2017 GHGRP data with the U.S. Department of Interior Bureau of Ocean Energy Management (BOEM)'s Gulfwide Offshore Activity Data System (GOADS) report for 2017 using mostly a manual process that involves qualitative judgement using facility names and GPS coordinates. The 2017 GOADS dataset contains 995 unique complex IDs, which for the purposes of this analysis represents the nationwide count of offshore production facilities using the subpart W definition of the source category. The BOEM data includes unit-level emissions data. This was used to determine facility-level emission estimates for non-subpart W reporters.
Therefore, it was determined that five facilities are expected to exceed the 25,000 mt CO2e threshold for the first time in the Offshore Petroleum and Natural Gas Production industry segment of subpart W as a result of the proposed AR5 GWP changes. 
Industry Segment 2: Onshore Petroleum and Natural Gas Production
Estimates of the number of facilities were found by combining RY2020 GHGRP data with data taken from Enverus' DI database (DI). DI does not provide any emissions data. As a result, a methodology was created to correlate the amount of CO2e emissions with the main nationwide data that was available: gas and oil production and well count per facility. 
Two correlations were made: one between GHGRP well emissions and well count and one between GHGRP throughput-based emissions and well count. For the well-based emissions, well counts were used to estimate a ratio of emissions to well counts. For each basin, the well-based emissions, in mt CO2e, were divided by the number of wells to derive basin-level emission ratios (mt CO2e emitted per each well). 
Similarly, production in barrels of oil equivalent (BOE) were used to estimate a ratio of BOE production to throughput-based emissions. For each basin, the total amount of GHG emissions, in metric tons of CO2e, was divided by the amount of BOE produced to derive basin-level emission ratios (metric tons of CO2e emitted per each BOE). 
Separate emission ratios were found for the old AR4 GWPs and the new AR5 GWPs. Emission ratios were used to calculate an approximate amount of BOE production that would equal the 25,000 mt CO2e.
Using the list of facilities from DI, it was determined that 40 facilities are expected to exceed the 25,000 mt CO2e threshold for the first time in the Onshore Petroleum and Natural Gas Production industry segment of subpart W as a result of the proposed AR5 GWP changes. 
Industry Segment 3: Onshore Natural Gas Processing
The three largest emission sources in the Onshore Natural Gas Processing industry segment are combustion, acid gas removal units, and flares. Using GHGRP data from RY2020, 98.8% of these emissions are from CO2 and 95.6% of the total emissions from the Onshore Natural Gas Processing industry segment are from CO2. Therefore, the proposed AR5 GWP changes, which only affect CH4 and N2O emissions, are not expected to impact overall CO2e emissions or the number of facilities subject to the Onshore Natural Gas Processing industry segment. 
Therefore, no facilities are expected to exceed the 25,000 mt CO2e threshold for the first time in the Onshore Natural Gas Processing industry segment of subpart W as a result of the proposed AR5 GWP changes.
Industry Segment 4: Onshore Natural Gas Transmission Compression
Transmission compression stations located on interstate pipelines report financial and operational information to the Federal Energy Regulatory Commission (FERC) under Form 2/2a. The FERC data does not include intrastate stations and we were unable to find any external data source which comprehensively includes intrastate station data.
Therefore, we downloaded FERC Form 2/2a data for 2020 which included the number of compressors and the annual gas consumption for 1,344 compressor stations operating on interstate pipelines. To obtain the number of both interstate and intrastate compressor stations, we used natural gas pipeline mileage for intrastate and interstate stations from the U.S. Department of Transportation (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) to calculate the ratio of total mileage to interstate mileage (1.54). Using the DOT PHMSA mileage ratio, we estimated 2,073 transmission compression stations (both intrastate and interstate stations, combined) nationwide. 
Utilizing the detailed information from FERC on interstate stations, we estimated the facility-level emissions in 2020 for each interstate station, following the methodology outlined in Annex 3.6 of the 2019 Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHGI).
Once emissions were estimated for each FERC interstate compressor station, the total facility-level emissions were compared to the direct emitter threshold to determine which interstate transmission compression facilities would be expected to report to the GHGRP after the proposed AR5 GWP changes. To estimate the intrastate stations that would exceed the direct emitter threshold, we first cross-walked the FERC data to the GHGRP data. Any facility reporting to the GHGRP in RY2020 that could not be cross-walked to the FERC data was assumed to be an intrastate station because the FERC data only includes interstate stations. Using the number of intrastate stations reporting to the GHGRP in RY2020 as determined by the crosswalk, we estimated the ratio of interstate stations to intrastate stations exceeding the direct emitter threshold. This ratio was then used to scale the known count of subject interstate stations and associated emissions to estimate the quantity of subject intrastate stations and associated emissions.
It was determined that 130 facilities are expected to exceed the 25,000 mt CO2e threshold for the first time in the Onshore Natural Gas Transmission Compression industry segment of subpart W as a result of the proposed AR5 GWP changes.
Industry Segment 5: Underground Natural Gas Storage
The key data used to assess the national count of facilities was taken from the annual report data submitted using EIA Form-191 "191 Field Level Storage Data (Annual)." Specifically, the count of active storage fields in the 2020 EIA Form-191 dataset was used in combination with a factor of 0.89 stations per field as found in Zimmerle et al to estimate the national count of stations. There are 387 active storage fields in the 2020 EIA Form-191 dataset, which yields an estimated 344 stations when combined with the Zimmerle et al. factor. We consider each station representative of a facility as defined in the GHGRP.
Outside of the GHGRP reporters, there are approximately 292 facilities for which emissions estimates were needed to facilitate the threshold analyses. The only outside data identified were from annual reports reflecting the submissions made by facilities using EIA Form-191 and EIA Form-176. These annual EIA datasets contain data on field capacity (e.g., base capacity, working capacity, maximum daily delivery), injections, and the disposition of gas from underground storage fields. We determined that the injections volume appeared to be most closely associated with GHGRP emissions data.
We developed a linear correlation between injections and CO2e using the RY2020 GHGRP data, updated using the new GWP values. Based upon this line of best fit, facility-level emissions estimates were generated for the 292 non-subpart W reporter Underground Natural Gas Storage  facilities. The facility-level emissions were compared to the direct emitter threshold to determine how many prospective facilities would be subject to the GHGRP after implementing the proposed AR5 GWP changes. The correlation resulted in seven fields greater than 25,000 mt CO2e and three fields just below 25,000 mt CO2e. To be conservative, we assumed that injection volumes would increase in the near future so that all 10 fields would meet the threshold. As described previously the underground storage data in EIA is by field, so to estimate the number of new stations (i.e., facilities), we scaled the fields exceeding the direct emitter threshold (10) by the Zimmerle et al. factor (0.89 stations/field) to arrive at nine new facilities.
Therefore, nine facilities are expected to exceed the 25,000 mt CO2e threshold for the first time in the Underground Natural Gas Storage industry segment of subpart W as a result of the proposed AR5 GWP changes.
Industry Segment 6: LNG Storage
A national count of the number of LNG storage stations was obtained from the annual report of data submitted by facilities using EIA Form-176 "Natural Gas Supply Items." In the EIA Form-176 dataset for 2020, there are 75 LNG storage facilities with information for LNG Facility Year End Capacity or LNG Storage Withdrawals Volume. For RY2020, five facilities reported emissions associated with LNG storage to the GHGRP. One of the companies in the EIA Form-176 dataset reports to the GHGRP under two different GHGRP IDs. Therefore, there are only four matching facilities between both datasets.
The emissions from the four RY2020 GHGRP reporters were updated using the proposed AR5 GWP changes and mapped to the EIA Form-176 dataset to establish a correlation. LNG Storage Withdrawals Volume showed the strongest correlation, assuming that the relationship between LNG storage withdrawals and CO2e was strictly linear, and that the relationship passed through the origin. Based upon this line of best fit, emissions estimates were generated for the 71 facilities within the EIA Form-176 dataset that were not matched to existing GHGRP reporters. Eight facilities had zero LNG Storage Withdrawals Volume reported to the EIA so only 63 have emissions.
Using the established correlation, only one of the 63 non-subpart W reporter facilities was estimated to have emissions greater than the 25,000 mt CO2e threshold. Therefore, one facility is expected to exceed the 25,000 mt CO2e threshold for the first time in the LNG Storage industry segment of subpart W as a result of the proposed AR5 GWP changes.
Industry Segment 7: LNG Import and Export Equipment
FERC maintains lists of existing LNG import facilities and LNG export facilities, resulting in a total of 14 LNG Import and Export Equipment facilities. We consider the FERC lists to contain a comprehensive list of nationwide LNG import and export equipment facilities for RY2020.
In addition to evaluating the nationwide total number of facilities in the LNG Import and Export Equipment industry segment, we also assessed the number of importers separately from exporters. For facilities that reported to the GHGRP, we assessed the quantity of LNG imports and exports reported from RY2015 to RY2020. Some facilities report imports and exports in the same year while some facilities report imports for certain years and exports for other years. In our assessment, these facilities were counted as both import and export facilities. There are four national facilities from the FERC dataset assigned to both categories and two GHGRP facilities assigned to both categories.
The GHGRP contains a total of 11 LNG import and export facilities. This count is based on facilities that reported to GHGRP in RY2020 and includes facilities with zero LNG throughput. As noted previously, if a facility is reporting to the GHGRP currently, we have assumed they will continue to do so regardless of the proposed AR5 GWP changes. Therefore, we expect all 11 LNG import/export facilities to continue to report. 
Based on the facility count assessment, there are three known LNG import facilities that have not reported GHG emissions to the GHGRP. According to the Department of Energy (DOE) Office of Oil and Gas LNG Monthly Reports, published in February 2021 and February 2022, none of the three LNG import facilities received LNG imports in 2020 or 2021. Therefore, their facility-level emissions are assumed to be zero for the near future.
Therefore, no facilities are expected to exceed the 25,000 mt CO2e threshold for the first time in the LNG Import and Export Equipment industry segment of subpart W as a result of the proposed AR5 GWP changes.
Industry Segment 8: Natural Gas Distribution
Natural gas distribution companies are required to report the miles of pipeline mains and the number of pipeline services by pipeline material annually to DOT PHMSA using Form F7100.1-1. There do not appear to be any thresholds for reporting to DOT PHMSA, so the data reported are considered a complete listing of every facility that operates distribution pipeline mains and services as they are defined by the DOT. For the purposes of our analysis, we removed data that were associated with any commodity other than natural gas (e.g., propane, landfill gas) as the GHGRP only requires reporting of equipment leak emissions from Natural Gas Distribution facilities. We also removed any reporting entities that only reported pipeline services with no pipeline mains as these were assumed to be transmission companies that have direct service lines to customers, but no distribution mains. After these adjustments, we consider the remaining 1,360 records -- each representing a facility as its defined in the GHGRP -- in the DOT PHMSA annual reports to be a nationally comprehensive repository of facilities and key activity data, which form the foundation of this coverage and threshold analysis for Natural Gas Distribution facilities. 
We first focused on the distribution mains and services emission sources, which typically account for 90% or more of the emissions reported to the GHGRP. There are pipeline materials that are included in the DOT PHMSA report that are not included in the GHGRP (e.g., recondition cast iron, ductile iron, other). Miles and services reported to DOT PHMSA under these materials were excluded from this analysis, which consisted of 0.1% of the mains and 3.3% of the services reported to PHMSA.
The DOT PHMSA data only contains activity data for distribution mains and services, but the GHGRP includes other emission sources for natural gas distribution, including transfer-distribution stations, metering and regulating stations, and combustion. After removing the emissions from transfer-distribution stations, metering and regulating stations, and combustion, the total remaining emissions from GHGRP facilities were directly compared to the total emissions from PHMSA. Accounting for the proposed AR5 GWPs in both estimates, the resulting pipeline emissions reported to PHMSA are nearly identical to the emissions reported to the GHGRP; meaning that 100% of the expected emissions are already reported to the GHGRP for Natural Gas Distribution facilities.
In RY2020, there were 164 Natural Gas Distribution facilities that reported to the GHGRP. This count is based on facilities that reported to GHGRP in RY2020 and includes facilities with emissions less than the 25,000 mt CO2e threshold. As noted previously, if a facility is reporting to the GHGRP currently, we have assumed they will continue to do so regardless of the proposed AR5 GWP changes.
Based on complete emissions coverage between PHMSA and GHGRP, there are no facilities expected to exceed the 25,000 mt CO2e threshold for the first time in the Natural Gas Distribution industry segment of subpart W as a result of the proposed AR5 GWP changes.
Industry Segment 9: Onshore Petroleum and Natural Gas Gathering and Boosting
Gathering and Boosting facilities and their component-level emissions are not well-characterized in any external (non-GHGRP) public dataset. As part of the 2020 updates to the GHGI, the EPA reviewed available sources for determining gathering and boosting activity and emissions data. The EPA detailed the results of their review in several memorandums, including "Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2018: Updates to Natural Gas Gathering & Boosting Station Emissions" and "Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2017: Updates to Natural Gas Gathering & Boosting Pipeline Emissions." The EPA concluded that, as subpart W reporting reflects data only from facilities that meet the reporting threshold, reported data must be scaled up to represent national total activity. For the purposes of this analysis, the GHGRP data is "scaled up" to estimate the non-GHGRP facility-level emissions.
In reviewing the data, we found that 122 facilities that have reported (or are currently reporting) to the GHGRP reported emissions are under the 25,000 mt CO2e threshold. For the purpose of our analysis, using the 122 facilities' emissions and throughputs with the portion of national production throughput not covered by the Gathering and Boosting industry segment in RY2020, we estimate there are approximately 34 non-GHGRP reporters. Of these, none are expected to exceed the direct emitter threshold after implementation of the proposed AR5 GWP changes. Therefore, there are no facilities expected to exceed the 25,000 mt CO2e threshold for the first time in the Onshore Petroleum and Natural Gas Gathering and Boosting industry segment of subpart W as a result of the proposed AR5 GWP changes.
Industry Segment 10: Onshore Natural Gas Transmission Pipeline
The key data used to assess the national count of facilities and associated emissions were taken from PHMSA Form 7100.2-1. This form contains a list of transmission pipeline owners and operators by operator ID and includes identifying information (e.g., company name, address) as well as transmission pipeline mileage by pipeline material type. Some modification of the PHMSA data was required such that they were consistent with the definition of facility, the definition of transmission pipeline, and the definition of owner or operator for the GHGRP industry segment.
The modifications to the PHMSA Form 7100.2-1 dataset included:
 Removing pipelines transporting any commodity other than natural gas;
 Removing any operator IDs that did not have onshore transmission pipeline mileage;
 Consolidating operator IDs, which involved aggregating the associated transmission pipeline mileage where the reported headquarters' address and company name were the same or similar to align records at the parent company level; and
 Mapping the existing GHGRP reporters to their PHMSA reported data.
The modifications yielded 667 unique parent companies (including the GHGRP facilities). We considered this to be the count of nationwide of transmission pipelines potentially subject to the GHGRP.
National- and facility-level emissions from transmission pipelines are estimated from equipment leaks and blowdowns along the pipeline. To estimate blowdown emissions, we used RY2020 reported GHGRP data for all onshore transmission pipeline facilities that reported to the GHGRP. To estimate blowdown emissions from non-reporting onshore transmission pipeline facilities, we used the RY2016 - RY2020 GHGRP reported blowdown emissions to develop nationwide CH4 and CO2 blowdown emission factors. These emission factors were estimated by dividing the GHGRP total reported emissions from blowdowns at Onshore Natural Gas Transmission Pipeline facilities by the GHGRP total reported miles of transmission pipelines. This method yielded an emission factor value of 0.71 mt CH4 per pipeline mile and 0.02 mt CO2 per pipeline mile. These emission factors were then used with the pipeline mileage activity data reported to PHMSA to estimate nationwide blowdown emissions from non-GHGRP reporting facilities. 
Therefore, only one facility is expected to exceed the 25,000 mt CO2e threshold for the first time in the Onshore Natural Gas Transmission Pipeline industry segment of subpart W as a result of the proposed AR5 GWP changes.
Total New Reporters for Subpart W
Table 4.9-4 shows the number of new reporters by industry segment for subpart W. As a result of the proposed AR5 GWPs, an additional 188 facilities are expected to report to subpart W.
Table 4.9-4. Total Number of New Reporters for Each Subpart W Industry Segment
Industry Segment
Number of New Reporters Resulting from GWP Changes
Offshore Petroleum and Natural Gas Production
7
Onshore Petroleum and Natural Gas Production
40
Onshore Natural Gas Processing
0
Onshore Natural Gas Transmission Compression
130
Underground Natural Gas Storage
9
LNG Storage
1
LNG Import and Export Equipment
0
Natural Gas Distribution
0
Onshore Petroleum and Natural Gas Gathering and Boosting
0
Onshore Natural Gas Transmission Pipeline
1
TOTAL
188

 4.10 Subpart DD
40 CFR part 98 subpart DD (subpart DD) currently requires reporting of GHG emissions from the electricity transmission and distribution sector. This source category currently consists of all electric transmission and distribution equipment and servicing inventory insulated with or containing SF6 or PFCs that are used within an electric power system (40 CFR 98.300(a)). Electric transmission and distribution equipment includes gas-insulated substations, circuit breakers, transformers, closed-pressure switchgear, hermetically sealed-pressure switchgear, gas-insulated lines, and gas storage containers (e.g., pressurized cylinder, gas carts). Facilities are required to report emissions of SF6 and PFCs, as well as other data used to verify the emissions are reported correctly. The SF6 and PFC emissions are multiplied by their respective GWPs to calculate the facility's CO2e emissions. SF6 is the most commonly used greenhouse gas within this sector and to date is the only gas that has been reported to the GHGRP. 
Under the current rule, any facility whose total nameplate capacity of SF6- and PFC-containing equipment (excluding hermetically sealed-pressure equipment) located at the facility or under common ownership or control that is greater than 17,280 pounds is subject to subpart DD (40 CFR 98.301(a)). Unlike other direct emitter subparts, subpart DD applicability is determined separately from all other subparts. Hence, being subject to another subpart (e.g., subpart D) does not make the facility subject to reporting under subpart DD and vice versa. Subpart DD facilities that also meet the applicability criteria for another subpart (e.g., subpart D) are directed to report their subpart DD data under a separate GHGRP ID.
EPA proposed several changes to this subpart to improve the quality of the data collected (87 FR 36920, June 21, 2022). These changes include (1) adding fluorinated greenhouse gases (F-GHGs) other than SF6 and PFCs to the monitoring, calculation, and reporting requirements; (2) revising the applicability criteria; (3) adding several new definitions; and (4) adding new procedures in 40 CFR 98.303(b) for measuring the nameplate capacity values for new and retiring equipment. 
EPA's proposal to establish a procedure allowing reporters to measure and revise the nameplate capacities of their new and retiring electrical equipment, if adopted, would increase the accuracy of the nameplate capacity values used in calculating emissions of SF6 and other insulating GHGs from electrical equipment. It also responds to a long-standing request from the industry for clarification on this matter. The proposed new procedures apply only to facilities that elect to measure the nameplate capacities of new and retiring equipment rather than relying on the rated nameplate capacities provided by equipment manufacturers. 
The proposed changes to applicability and the gases reported address the recent development by equipment manufacturers of new insulating gases that have much lower GWPs than SF6 or PFCs. These gases have begun to be used in some applications in other countries and the EPA is aware that some electric power systems are currently using or considering using these alternative gases in the United States. Although currently used in only small quantities, it is likely their use in the United States will increase. The new gases include fluoroketones and fluoronitriles, which are used as mixtures with carrier gases. These mixtures have much lower GWPs, ranging from less than 1 for fluoroketones to 300 - 500 for fluoronitriles. Table 4.10-1 lists the alternative gases currently available for use in this sector with their typical compositions and GWPs. It is likely that GHG emissions for this sector will decrease in the future due to the lower GWPs of these gases and because they are used only as dilute mixtures. However, we expect the new gases to be adopted slowly over the next decades due to the limited range of products currently marketed and the long lifetime of existing electrical equipment (typically over 40 years). 
Table 4.10-1. Composition of Alternative Gases Currently Available for Use in Electric Transmission and Distribution Equipment
                                Characteristics
                               CF4-Fluoronitrile
                               CF5-Fluoroketone
Chemical Formula
(CF3)2CFCN
(CF3)2CFC(O)CF3
100 Year GWP of Gas
2,100
<1
Typical Composition of Mixture
3  -  5% (CF3)2CFCN
95  -  97% CO2 and O2
10% (CF3)2CFC(O)CF3
90% mixture of O2 and N2, or CO2
100 Year GWP of Mixture
<500
<1

With the potential for alternate gases to become widely used in the future, the EPA has proposed changes to the current applicability threshold. Currently, a facility becomes subject to subpart DD if the total nameplate capacity of SF6- and PFC-containing equipment (excluding hermetically sealed-pressure equipment) located within the facility, when added to the total nameplate capacity of SF6- and PFC-containing equipment (excluding hermetically sealed-pressure equipment) that is not located within the facility but is under common ownership or control, exceeds 17,820 pounds. This threshold was calculated by EPA during the development of subpart DD to establish a nameplate capacity that approximates a typical nameplate capacity that would be expected to emit 25,000 mt CO2e if filled with SF6. To determine applicability, facilities would calculate CO2e emissions using the proposed new Equation DD-1, which accounts for the GWP of gases used and is an estimate of potential emissions from the source that may differ from the actual emissions reported under this subpart. The actual emissions are calculated annually using a mass-balance equation provided in the rule. The actual emissions may be significantly lower than the applicability emissions when a facility has implemented emission reduction practices.
In addition to the proposed amendments described above, EPA proposed updating the GWPs in Table A-1 to subpart A. The GWP change expected to affect subpart DD emissions is shown in Table 4.10-2. 
Table 4.10-2. Applicable GWP Change for Subpart DD
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
SF6
22,800
23,500
Increase

This analysis determined the impact of the revised AR5 GWPs and proposed reporting of other F-GHGs on the number of new reporters. For this analysis, we recalculated the CO2e for existing reporters using the SF6 emissions they reported in RY2020 and the AR5 GWP of 23,500. The method used to evaluate reporter burden consists of three steps, as follows:
 Identify currently reporting facilities reporting less than 25,000 mt CO2e per year that are on track to off-ramp but who are expected to begin reporting above 25,000 mt CO2e per year again as a result of the AR5 GWP change.
 Identify previously off-ramped subpart DD facilities and determine whether they will potentially re-enter the GHGRP as a result of the AR5 GWP change.
 Identify facilities that are not currently subject to the GHGRP and assess their potential to begin reporting as a result of the AR5 GWP change.
4.10.1 Current Reporters
Subpart DD has a number of facilities in the process of off-ramping (i.e., below 25,000 mt CO2e for RY2020 but not yet meeting the required number of years below the threshold). We used the SF6 emissions from the last year they reported to recalculate the CO2e using the AR5 GWP. The recalculated CO2e values for these facilities were then compared to the 25,000 mt CO2e threshold to determine whether any of the existing reporters would likely become ineligible to off-ramp. 
To determine the impact on these facilities, we first examined the CO2e for facilities that reported emissions between 24,300 and 25,000 mt CO2e using the current GWP of 22,800 in RY2020. Two facilities (1000326 and 1008343) reported RY2020 CO2e within this range. In Table 4.10-3, the CO2e for the past five years calculated using the existing GWP are compared with the values calculated using the AR5 GWPs. The CO2e for each facility would increase by approximately 3%.
Table 4.10-3. Recalculated CO2e from Potential Off-Ramping Facilities
                                  Facility ID
                                      GWP
                                    RY2016
                                    RY2017
                                    RY2018
                                    RY2019
                                    RY2020
1000326
22,800
62,372
43,219
57,191
34,925
24,345

23,500
64,287
44,546
58,947
35,997
25,092
1008343
22,800
34,109
12,390
1,053
3,625
24,632

23,500
35,156
12,770
1,085
3,736
25,389

Based on the current GWP, facility 1000326 may have become eligible to stop reporting in future years if emissions remained at the current level. However, this facility would likely be ineligible to cease reporting if the AR5 GWP for SF6 is adopted based on their RY2020. Facility 1008343 could have ceased reporting after RY2019 due to reporting three years of emissions less than 15,000 mt CO2e. However, if the AR5 GWP for SF6 is adopted and emissions for this facility remain at the level reported in RY2020, this facility would no longer qualify for the off-ramp and would be required to continue reporting.
Based on these conservative assumptions, we determined that an additional two facilities are expected to report to subpart DD as a result of the proposed revised AR5 GWPs. 
We also considered the impact of the proposed reporting of the new insulating gases (i.e., fluoronitriles and fluoroketones) on these reporters. Since EPA does not currently collect data on these gases, we do not know how many facilities currently use these alternatives and are not able to quantify the potential change in CO2e emissions for each facility. Instead, we assessed how much emissions of these gases would be needed to have an impact. For current and previous reporters whose CO2e is below 25,000 mt, we calculated the theoretical amount of CF4-fluoronitrile required to bring the facility above the 25,000 mt CO2e threshold. We selected CF4-fluoronitrile for this analysis because it has the highest GWP of the currently available alternative gases. We then qualitatively assessed whether any facility would be likely to emit CF4-fluoronitrile in the quantity calculated using information on the current availability and use of equipment containing CF4-fluoronitrile as the insulating gas.
In this analysis, we considered the facility with emissions closest to 25,000 mt CO2e using the AR5 GWP without being over this threshold. The facility (GHGRP ID 1009894) with the highest recalculated CO2e had 23,856 mt CO2e (equivalent to 1.015 mt SF6). We then calculated the amount of gas that would be required to emit the 1,144 mt CO2e to reach the 25,000 mt CO2e threshold. Assuming the use of CF4-fluoronitrile, the facility would need to emit 0.545 mt of CF4-fluorontirile. Using an annual emission factor of 0.1 (the same as assumed in Equation DD-1) and assuming a 5% CF4-fluoronitrile gas mixture, 0.545 mt is equivalent to emitting 10.9 mt of CF4-fluoronitrile gas mixture; more than 10 times the SF6 emissions reported by this facility in RY2020. As we noted earlier, the new insulating gases became available only in the last few years and are currently used in only small quantities. We consider it unlikely that any facility in the United States currently has CF4-fluoronitrile emissions this high. 
Based on these conservative assumptions and the resulting high amount of CF4-fluoronitrile gas that would be required to exceed the 25,000 mt CO2e threshold, we determined that no existing reporters are potentially impacted by the proposed reporting of the new insulating gases.
4.10.2 New Reporters
4.10.2.1 Analyses of Previously Off-Ramped Facilities
Subpart DD has a number of previous reporters who off-ramped from reporting prior to RY2020. We used the SF6 emissions from the last year they reported to recalculate the CO2e using the AR5 GWP. The recalculated CO2e values for these facilities were then compared to the 25,000 mt CO2e threshold to determine whether any of the facilities that previously off-ramped would be required to recommence reporting again. 
Using the last year of reported emissions for each facility that off-ramped, we recalculated CO2e using the AR5 GWP for SF6. No facility had recalculated emissions greater than 25,000 mt CO2e. 
Next, we considered whether the reporting of the new gases (i.e., fluoronitriles and fluoroketones) would be likely to bring the total CO2e emissions above the 25,000 mt threshold that would require the off-ramped facility to recommence reporting. The highest CO2e emissions reported by any of these facilities in their final year reporting was 15,645 mt CO2e. Similar to the analysis in the previous section, we calculated this facility would need to emit 4.45 mt CF4-fluoronitirile (pure gas, not as-used) (equivalent to 89 mt of a 5% CF4-fluoronitirile gas mixture) in order to exceed the 25,000 mt CO2e threshold. Assuming a 10% emission rate, this amount corresponds to having approximately 44.5 mt CF4-fluoronitirile (pure gas, not as-used) contained in equipment (or 898 mt nameplate capacity of equipment for a 5% CF4-fluoronitirile gas mixture). As we noted earlier, the new insulating gases became available only in the last few years and are currently used in only small quantities. We consider it unlikely that any facility in the United States currently has CF4-fluoronitrile emissions this high. 
Based on these conservative assumptions and the resulting high amount of CF4-fluoronitrile gas-containing equipment that would be required to exceed the threshold, we consider it unlikely that the proposed changes to the SF6 GWP and the proposed reporting of other F-GHGs would result in any facility that previously off-ramped being required to begin reporting again.
4.10.2.2 Analyses of Non-Reporters Entering the GHGRP 
To determine whether any new facilities would be required to report if the proposed changes are adopted, we used the proposed applicability Equation DD-1 to calculate the CO2e for a facility using only SF6 and having 17,280 pounds of nameplate capacity, excluding hermetically sealed-pressure equipment (i.e., the current applicability threshold). We then calculated the additional nameplate capacity of CF4-fluoronitrile equipment required for the facility to exceed the proposed 25,000 mt CO2e threshold. We then qualitatively assessed whether any facility would be likely to have nameplate capacity of CF4-fluoronitrile in the quantity calculated using information on the current availability and use of equipment using CF4-fluoronitrile. 
Assuming the SF6 AR5 GWP of 23,500, for the weight fraction of SF6 in the insulating gas, and the proposed Equation DD-1, the applicability threshold is 23,453 lbs of nameplate capacity, if only SF6 is used. The current nameplate capacity threshold of 17,280 lbs is more conservative (i.e., more facilities are subject to this subpart) than using the proposed Equation DD-1 with a 25,000 mt CO2e threshold. A facility that has a total nameplate capacity (excluding hermetically sealed-pressure equipment) of less than 17,280 pounds and uses only SF6 would not become subject to reporting as a result of the proposed new applicability criteria and newly proposed GWP for SF6.
If a facility is using one of the new alternative gases, then it is theoretically possible for a facility to become subject to subpart DD because of the proposed new applicability criteria. However, the lower GWP and smaller mass fraction of the gas used make it unlikely a facility would become subject to reporting. For example, a facility that uses SF6 in equipment with a total nameplate capacity (excluding hermetically sealed-pressure equipment) of 17,280 lbs would estimate emissions for comparison to the applicability threshold of 18,419 mt CO2e based on the AR5 GWP of 23,500. This facility would need an additional 6,581 mt CO2e in estimated emissions to exceed the proposed 25,000 mt CO2e threshold. Emissions of 6,581 mt CO2e for a facility using a 5% mixture of CF4-fluoronitrile and assuming a 0.1 emission factor is equivalent to operating a total nameplate capacity of 1,381,771 lbs. As noted above, use of the new insulating gases is currently very limited and expected to grow slowly over the next several years. We consider it to be very unlikely that any facility will operate over 1.3 million pounds of total nameplate capacity (excluding hermetically sealed-pressure equipment) containing the new insulating gases (while simultaneously having less than 18,000 lbs of total SF6 nameplate capacity) within the next three years.
For this reason, we conclude that no new reporters are likely to become subject to this subpart due to the proposed new applicability criteria and proposed revised AR5 GWPs. 
We do not expect the newly proposed procedures for measuring the capacity of new and retiring electrical equipment to have a significant impact on the number of facilities required to report. Some facilities may continue to use the nameplate capacity as allowed in the existing rule. For reporters that elect to use the proposed new procedures, the difference between the measured capacity and the manufacturer's nameplate capacity for each unit is expected to be small. The emissions may increase or decrease depending on whether the measured value for each individual unit is greater than or less than the nameplate capacity. The overall impact on reported emissions is expected to be minimal as only a few new units enter service and a few old units are retired during a typical calendar year. 
 4.11 Subpart FF
40 CFR part 98 subpart FF (subpart FF) requires reporting of GHG emissions from active underground coal mines. Active underground mines are defined as those where mine development is underway, coal has been produced within the last 90 days, mine personnel are present in the mine workings, mine ventilation fans are operative, or when the mine is designated as an "intermittent" mine by the Mine Safety and Health Administration (MSHA). Subpart FF does not include emissions from abandoned underground mines or surface mines.
Subpart FF is a direct emitter subpart with a reporting threshold in cubic feet of methane rather than metric tons of CO2. An owner/operator of an underground coal mine must report to the GHGRP if the mine liberates at least 36.5 million cubic feet (mmcf) per year of CH4. This equates to approximately 701 mt of methane per year or 17,525 mt CO2e per year at a GWP of 25 for CH4. Liberated means methane released from coal and surrounding rock strata during the mining process. Note that the quantity of methane liberated may not equal the quantity of methane emissions because some subpart FF facilities recover and use methane, reducing the quantity of methane that is emitted to the atmosphere.
For subpart FF, the GWP changes shown in Table 4.11-1 are expected to affect reported emissions. 
Table 4.11-1. Applicable GWP Changes for Subpart FF
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
CH4
25
28
Increase
N2O
298
265
No Impact 

4.11.1 New Reporters
Although the number of subpart FF facilities declined steadily between 2014 and 2019, five new facilities reported in RY2020 for a net increase of two facilities since RY2019. Conservatively, we assumed two new reporters each year in RY2021, RY2022, and RY2023. However, because the reporting threshold is based on cubic feet of methane versus metric tons of CO2, the change to AR5 GWP does not appear to be the driving factor for these six new reporting facilities.
As of RY2020, subpart FF facilities have only used the 3-year off-ramp provisions (40 CFR 98.2(i)(1) and 98.2(i)(2)). We reviewed all facilities that have claimed the 3-year off-ramp since reporting began in RY2011 to determine if any facility could become new reporters using the AR5 GWPs. Facilities that are no longer eligible for the off-ramp were added to the total number of reporting facilities for RY2023. 
Only five facilities have claimed this off-ramp since 2011. We considered whether emissions reported to subparts C and D, in addition to subpart FF emissions, would impact facility emissions. None of the facilities reported either subpart. Therefore, the changes to AR5 GWPs will not impact any subpart FF facilities' eligibility for off-ramping.
We also reviewed the 39 subpart FF facilities that notified EPA of their intent to cease reporting since RY2011. We confirmed that all facilities remain closed through review of data on MSHA operating status. 
Therefore, the change to AR5 GWPs would not result in new reporters. Thus, there is no change to the number of affected facilities in subpart FF for previously off-ramped facilities.
 4.12 Subpart HH
40 CFR part 98 subpart HH (subpart HH) requires reporting of CH4 emissions from municipal solid waste (MSW) landfills that accepted waste on or after January 1, 1980, and which generate CH4 equal to or greater than 25,000 mt CO2e annually. However, the facility is not required to report if all three of the following criteria are true:
 The MSW landfill did not receive waste on or after January 1, 2013; 
 The MSW landfill had CH4 generation as determined using specified subpart HH calculations of less than 1,190 mt of CH4 in the 2013 reporting year; and
 The owner or operator of the MSW landfill was not required to submit an annual report under any requirement of part 98 in any reporting year prior to 2013. 
Landfill gas consists primarily of CO2 and CH4 and is produced by anaerobic bacteria digesting organic waste in the landfill. As CH4 migrates through the landfill, some of it is converted to CO2 through oxidation. The amount of CH4 oxidized to CO2 may be subtracted from generation when determining applicability to subpart HH. Once a landfill is subject to reporting under subpart HH, the landfill reports annual CH4 emissions. For landfills that do not use a gas collection and control system (GCCS), CH4 emissions from the landfill equal CH4 generation adjusted (i.e., reduced) for oxidation. For landfills that do use a GCCS, CH4 emissions equal CH4 generation adjusted for oxidation, and adjusted for CH4 collected and destroyed on-site and/or sent off-site. Landfill facilities may stop reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2) provided they submit a notification to the EPA that announces the cessation of reporting and explains the reasons for the reduction in emissions. To stay out of the program, landfills must monitor their emissions annually to ensure they remain below 25,000 mt CO2e each year.
Landfills that are uncontrolled report GHGRP emissions using Equation HH-5, which is Equation HH-1 adjusted for oxidation. Equation HH-1 is a first order decay model that incorporates the amount of waste in a landfill, the degradable organic carbon (DOC) content of the waste, and a decay rate constant (k). Default values for DOC and k are listed in Table HH-1 and are selected based on three options for characterizing waste in HH-1 calculations: the bulk waste option, the modified bulk waste option, and the waste-specific option. EPA proposed changing some of the DOC and k values in Table HH-1 in June 2022. Table 4.12-1 shows these proposed changes.
Table 4.12-1. Proposed Changes and Additions to Select DOC and k Values in Table HH-1[a]
                                    Factor
                             Current Default Value
                            Proposed Default Value
                                     Units
DOC (bulk waste)
                                     0.20
                                     0.17
Weight fraction, wet basis.
DOC (bulk MSW, excluding inerts and C&D waste)
                                     0.31
                                     0.27

DOC (Uncharacterized MSW)
                                    ---[b]
                                     0.32

k values for Bulk Waste option and Modified Bulk MSW option
k (precipitation plus recirculated leachate <20 inches/year)
                                     0.02
                                     0.055
yr[−1]
k (precipitation plus recirculated leachate 20-40 inches/year)
                                     0.038
                                     0.111

k (precipitation plus recirculated leachate >40 inches/year)
                                     0.057
                                     0.142

k (uncharacterized MSW)
                                    ---[b]
                                0.055 to 0.142

[a] DOC = degradable organic carbon; k = methane decay rate constant
[b] Does not exist in the current version of Table HH-1

While uncontrolled landfills only report emissions using Equation HH-5, controlled landfills may report emissions with Equation HH-6 or Equation HH-8. For both equations, emissions equal generation minus the amount of CH4 that is recovered and destroyed and/or sent off-site. Equation HH-6 incorporates generation from Equation HH-1 while Equation HH-8 incorporates generation from Equation HH-7, which is based on the amount of CH4 recovered.
All GHGRP reported emissions must be converted to CO2e using the GWP for CH4. Table 4.12-2 shows the proposed AR5 GWP change for CH4. 
Table 4.12-2. Applicable GWP Change for Subpart HH
GHG
Current GWP
AR5 GWP
                                      CH4
                                      25
                                      28
4.12.1 Current Reporters
In reviewing GHGRP data for RY2021 (extracted from Envirofacts on May 13, 2022), we identified 23 landfills that qualify for off-ramping in 2022, either because their 2021 emissions represent the fifth consecutive year of emissions being below 25,000 mt CO2e or they represent the third consecutive year of emissions being below 15,000 mt CO2e. For purposes of this analysis, we are assuming these 23 sites will stop reporting (i.e., off-ramp) in 2022. 
We also identified 7 closed sites and 13 open sites for which 2021 emissions represented the second consecutive year of emissions being less than 15,000 mt CO2e and third-year emissions in 2022 are estimated to be less than 15,000 mt CO2e too. For purposes of this analysis, we are assuming these 20 sites will stop reporting in 2023.
4.12.2 New Reporters
4.12.2.1 Analyses of Previously Off-Ramped Facilities 
Based on a review of reported subpart HH data, as of RY2020, 179 landfills have stopped reporting to the GHGRP based on qualifying emissions and notification to EPA. A few other landfills with qualifying emissions have also stopped reporting but have not notified EPA; therefore, we are not evaluating these landfills in the burden analysis (due to lack of notification). 
In summary, we identified 179 sites that have off-ramped. In 2023, these facilities will have to monitor their emissions using the new values for DOC, k, and GWP, where applicable to ensure their emissions are below 25,000 mt CO2e. While all sites will have to use the new GWP to evaluate emissions, only sites that monitor emissions with Equations HH-1 and HH-6 will have to use the new DOC and k values (sites that monitor emissions with Equations HH-7 and HH-8 do not use these values).
Landfills can off-ramp whether they are open or closed, as long as CH4 emissions meet the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2). For uncontrolled landfills, CH4 generation adjusted for oxidation must be below these levels to off-ramp. Controlled landfills can meet these levels by reducing generation through use of a GCCS. When a landfill is open, its CH4 generation increases each year and reaches maximum generation the last year of waste acceptance. After a landfill is closed, CH4 generation decreases each year. For landfills that were closed their last year of reporting, their CH4 generation in 2023 will be less than what it was their last year of reporting. For landfills that were open their last year of reporting, generation will increase until they close. Due to the differences in CH4 generation between open and closed landfills, we assessed potential reporting burden differently for these two groups of landfills.
To evaluate reporting burden to off-ramped landfills that were closed their last year of reporting, we calculated their 2023 emissions using new and existing values for DOC, k, and GWP, where applicable and compared the changes. For uncontrolled sites we calculated their HH-1/HH-5 emissions and for controlled sites we estimated their last roll-up emissions (HH-6 or HH-8 emissions). Since we did not have information on CH4 recovery in 2023, we had to modify our calculations of HH-6 and HH-8 emissions, as described below. 
For controlled landfills, CH4 emissions equal the amount of CH4 generated minus the amount of CH4 captured and controlled. For HH-8, both terms (CH4 generation and the amount of CH4 captured and controlled) are calculated based on recovered CH4. In lieu of not knowing recovery, we assumed a facility's HH-8 roll-up emissions equaled their existing emissions in 2023. To calculate "new" HH-8 emissions for 2023, we increased the existing emissions by 12%, which is the percent change associated with increasing the GWP for CH4 from 25 to 28.
For controlled landfills reporting with HH-6 emissions, in lieu of not knowing their recovery, we assumed their generation (which is calculated using HH-1) equaled their facility emissions in 2023. We calculated new and existing HH-1 generations in 2023 based on a site's annual waste acceptance rate, and new and existing values for DOC and k associated with the bulk waste option. We chose values associated with the bulk waste option as it is one of the most frequently selected options by GHGRP reporters. Referring to Table 4.12-1, the bulk waste option values we used were 0.20 for existing DOC; 0.17 for new DOC; 0.038 for existing k; and 0.111 for new k. We adjusted existing and new HH-1 generations for 10% oxidation and converted them to CO2e using the new and existing GWPs (28 and 25, respectively). 
For uncontrolled sites, we calculated new and existing HH-5 emissions, which are HH-1 generation emissions adjusted for oxidation. We calculated new and existing HH-1 generations based on a site's annual waste acceptance rate, and new and existing values for DOC and k associated with the bulk waste option. We adjusted both generations for 10% oxidation and converted them to CO2e using the new and existing GWPs.
We also evaluated the reporting burden for off-ramped landfills that are currently open. Most open landfills that off-ramped used a GCCS to reduce emissions below 25,000 mt CO2e. Since generation increases from open landfills, over time their generation may become too great to maintain generation below 25,000 mt CO2e with their GCCS. Therefore, some open sites that off-ramped are expected to report again in the future. To assess burden, we estimated the maximum generation from open sites that have off-ramped using both new and existing values of DOC, k, and GWP. We evaluated whether both maximum generations might lead to reporting again or if only the new maximum generation would trigger reporting.
We identified 179 sites that have off-ramped. To evaluate reporting burden for closed landfills that have off-ramped, we calculated their 2023 emissions using new and existing values for DOC, k, and GWP and compared the changes. For controlled sites, we calculated their HH-6 or HH-8 emissions in 2023 (depending on which equation they last reported with), and for uncontrolled sites we calculated their HH-5 emissions in 2023.
For closed landfills that selected their HH-6 emissions as their final roll-up emissions before off-ramping we modeled existing and new HH-6 emissions in 2023 using a first order decay equation to determine if new values of DOC, k, and GWP would increase generation. Except for one landfill, the combination of these parameters led to negative percent changes in generation, indicating that the combined effect of the proposed new changes to DOC, k, and GWP accelerates the decline of HH-6 emissions from closed landfills. Due to their decreasing generation, we do not believe these closed landfills will report again. We also believe the one landfill that saw a positive change (14%) is an anomaly (likely due to the "screening nature" of our generation calculation) as this landfill last reported in 2018, and emissions were less than 15,000 CO2e.
For closed landfills that selected their HH-8 emissions as their final roll-up emissions before off-ramping, we used these final emissions as their 2023 HH-8 emissions. We then increased these "existing" emissions by 12% (GWP percent change proposed) to estimate "new" emissions in 2023. None of the "new" emissions reached 25,000 mt CO2e, indicating that existing emissions are low enough that increasing them by 12% in 2023 will not trigger reporting. Based on these results, we do not believe these landfills will report again due to their decreasing emissions. 
For the closed, uncontrolled landfills that have off-ramped, we modeled existing and new HH-5 emissions in 2023 using a first order decay equation to determine the impact of the new values of DOC, k, and GWP on generation. Except for one landfill, the combination of these parameters led to negative percent changes in generation, indicating that the combined effect of the proposed new changes to DOC, k, and GWP accelerates the decline of generation emissions (HH-1/HH-5) from closed landfills. Due to their decreasing generation, we do not believe these closed landfills will report again. We also believe the one landfill that saw a positive change (14%) in generation is an anomaly (likely due to the "screening nature" of our generation calculation) as this landfill last reported in 2012, and emissions were less than 15,000 mt CO2e.
For the open landfills where we modeled maximum generations using new and existing values for DOC, k, and GWP, all but five had similar new and existing generations (within +-7% of one another). For landfills with similar new and existing generations, we are not counting the new changes to DOC, k, and GWP as a burden to these landfills as we believe their similar generations will trigger the same reporting requirement in the future. On the other hand, for the five landfills where the new maximum generation is somewhat higher than existing generation (11%, 23%, 30%, 30%, and 31% differences at the five landfills) the new maximum generation may cause reporting that the existing generation might not. Note, while open landfills that have off-ramped have increasing generation each year (since they're open), if they keep emissions below 25,000 mt CO2e by upgrading or expanding their GCCS they can remain out of the program. This might be the case for the five landfills we modeled with slightly higher new maximum generations. However, to be conservative, we determined that an additional five landfills are expected to report to subpart HH as a result of the proposed revised AR5 GWPs.
4.12.2.2 Analyses of Non-Reporters Entering the GHGRP
For landfills that have never reported to the GHGRP, we estimated burden to this group based on how many nonreporters would have to report only because of proposed changes to DOC, k, and GWP. In other words, if existing values of DOC, k, and GWP eventually require a nonreporting facility to report, we did not count this as a burden to the facility. We used RY2024 to evaluate the effect of the new changes on nonreporters as the rule states that for nonreporters, reporting with new values starts the RY following their publication.
As noted earlier, landfills are subject to reporting if their generation equals or exceeds 25,000 mt CO2e. Assuming all nonreporting landfills are complying with the rule, (i.e., assuming none have reached 25,000 mt CO2e), nonreporting landfills are either (1) open landfills that have not reported because their generation has not reached 25,000 mt CO2e or (2) they are closed landfills that did not generate 25,000 CO2e or more while they were open.
To conduct a burden analysis, we identified nonreporting landfills using the EPA's Landfill Methane Outreach Program (LMOP) Landfill and Landfill Gas Energy Database (LMOP database). The LMOP database currently contains information on 2,634 MSW landfills, which represents the majority of MSW landfills in the United States. The database contains various information about the landfills such as physical address, latitude and longitude, owner/operator organization, operational status, year opened, actual or expected closure year, design capacity, amount of waste in place (WIP), gas collection system status, and GHGRP ID (if a landfill has ever reported to the GHGRP).
The LMOP database was last updated March 2022 and includes 1,307 landfills that have never reported to the GHGRP. Based on available closure information, 1,003 of these landfills received waste on or after January 1, 1980, which makes them potentially subject to subpart HH. Based on available information on design capacity and opening and closure years, we were able to model generation in RY2024 for 119 of these landfills. We modeled generation using new and existing values of DOC and k associated with the bulk waste option; adjusting the generations for 10% oxidation; and converting them to CO2e using the new and existing GWPs (28 and 25, respectively). We then assessed the magnitude of these generations and whether we thought they would trigger reporting in the future.
We were able to model generation from 119 landfills that have never reported to the GHGRP, presumably because their generation has never reached 25,000 mt CO2e. Of these modeled landfills, 85 were closed and 34 were open. To evaluate reporting burden for these landfills, we evaluated their maximum generation using new and existing DOC, k, and GWP values.
For the 85 closed nonreporting landfills we modeled, all but three had "new" generation emissions in 2024 that were less than their existing generation emissions in 2024. As noted above, these findings indicate that the combined effect of the June 2022 proposed changes to DOC, k, and GWP accelerates the decline in generation from closed landfills. Since these landfills are closed and have never reported, this means their generation never reached 25,000 mt CO2e while they were open. Now that they're closed, their existing generation in 2024 is even further below 25,000 mt CO2e. The proposed changes indicate that their "new" emissions will be even further below existing levels, therefore we do not believe these 85 closed landfills will report again. In fact, based on these results, we do not believe any landfill that is closed and has not reported to the GHGRP will be required to report in the future.
Regarding the three closed landfills that had positive changes in their generation (2%, 3%, and 16% positive differences), we believe the results are an anomaly, and a product of the "screening" nature of our calculations. We believe these landfills have emissions below 25,000 mt CO2e since these landfills are closed and have never reported, meaning when they were open, their generation never reached 25,000 mt CO2e to trigger reporting. Furthermore, by 2024 all three landfills will have been closed for 19, 24, and 41 years. Therefore, we do not believe these three closed landfills will have to report in the future.
For the 34 open nonreporting landfills we evaluated based on new and existing maximum generations (using new and existing values for DOC, k, and GWP), our results indicate that 24 landfills will eventually exceed 25,000 mt CO2e in generation using either new or existing values for DOC, k, and GWP, thus, we are not counting the new values as a reporting burden to these landfills. For nine landfills, existing and new maximum generations are not expected to reach 25,000 mt CO2e, while for one landfill, its new maximum generation exceeded 25,000 mt CO2e while its existing maximum generation did not. Thus, this one additional landfill is expected to report to subpart HH as a result of the proposed revised AR5 GWPs.
 4.13 Subpart II
40 CFR part 98 subpart II (subpart II) requires reporting of GHG emissions from industrial wastewater and treatment sludge sources at pulp and paper manufacturing, food processing, ethanol production, and petroleum refining facilities. Facilities reporting to subpart II are typically required to report to the GHGRP because emissions from primary industrial activities at the facility are regulated under other subparts (e.g., subpart Y [Petroleum Refineries] and subpart AA [Pulp and Paper Manufacturing]). Facilities must also report to subpart C (Stationary Combustion) if the wastewater treatment system is associated with a biogas destruction device or if there are other stationary combustion sources on site at the facility.
Subpart II facilities are required to report the amount of CH4 generated, emitted, and/or recovered from the following sources: anaerobic lagoons or reactors, anaerobic sludge digesters, and biogas collection and destruction devices. Since industrial wastewater treatment facilities are expected to produce little to no CO2 or N2O if functioning properly, only the CH4 content of the biogas is included in the net GHG emissions under the GHGRP. As shown in Table 4.13-1, the GWP for CH4 being increased from 25 to 28 will increase calculated CO2e emissions and has the potential to increase the number of facilities reporting to the GHGRP. 
Table 4.13-1. Applicable GWP Changes for Subpart II
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
                                      CH4
                                      25
                                      28
                                   Increase

Facilities that are subject to reporting under subpart II may stop reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2). The burden evaluation is presented for off-ramped facilities as of RY2020, projected off-ramp facilities that may be brought back into the program in RY2023 with the new CH4 GWP, and facilities that may be required to start reporting to the GHGRP for the first time after the GWP revisions are adopted. We assumed the GWP revisions will be incorporated for RY2023 for active and off-ramped reporters and for RY2024 for new reporters. 
All petroleum refineries subject to subpart Y are required to report to the GHGRP. Similarly, all pulp and paper manufacturing facilities with anaerobic treatment sources are expected to meet the reporting requirements of emitting 25,000 mt CO2e or more annually. Emissions from petroleum refineries and pulp and paper manufacturing facilities will exceed their reporting thresholds based on their subpart C, subpart Y, and/or subpart AA CO2e emissions alone. Increased subpart II emissions from the new AR5 CH4 GWP will not affect the reporting status of these facilities because subpart II emissions typically have minor contributions to the overall facility emissions at these industrial sites. Furthermore, the AR5 CH4 GWP increase for subpart C (and any subparts using subpart C combustion factors) was determined to be offset by the AR5 N2O GWP decrease, resulting in negligible changes in subpart C emissions (as discussed in Section 2.2). The burden evaluation methodology for subpart II focused on subpart II facilities that do not also report to subpart Y and AA.
4.13.1 Current Reporters
Each subpart II facility with emissions less than 25,000 mt CO2e were further evaluated to determine whether they are projected to off-ramp. 
For this analysis, projected off-ramp facilities are defined as those that are assumed to cease reporting prior to RY2023. To determine this group of facilities, RY2021 and RY2022 emissions were estimated using past reported data for all applicable subpart II facilities. Additionally, the variability of prior year data was reviewed to determine if emissions were consistent or inconsistent. For cases where prior year (RY2016 to RY2020) emissions were consistently below off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2) and the facility is eligible to cease reporting for the first time in either RY2021 or RY2022, it was assumed that these facilities will cease reporting prior to RY2023. This subset of facilities was then evaluated to determine if the subpart II CH4 increase in RY2023 would raise emissions over the 25,000 mt CO2e threshold. If this is true, then the facility was assumed to incur burden because they would be brought back into the program. 
There are four facilities that reported emissions below 25,000 mt CO2e in 2020. We expect that three of those facilities will off-ramp prior to RY2023 because their emissions were consistent over the past five years and below 25,000 mt CO2e. Net emissions from these three facilities will stay below the 25,000 mt CO2e threshold after applying the AR5 CH4 GWP. The fourth facility does not meet the off-ramp requirements prior to RY2023 due to emissions exceeding 25,000 mt CO2e within the past five reporting years. Thus, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs from projected off-ramp subpart II reporting facilities.
4.13.2 New Reporters
4.13.2.1 Analyses of Previously Off-Ramped Facilities 
For subpart II, we evaluated impacts on facilities that have already ceased reporting due to the off-ramp provisions between RY2014 to RY2020. These subpart II facilities were filtered to exclude facilities that also report subpart Y and subpart AA annual emissions, as they are expected to exceed the reporting thresholds for those subparts alone and will still report regardless of the AR5 CH4 GWP revision. The CO2e emission values for the remaining subpart II facilities were ranked from high to low, and then the facilities were evaluated after calculating the new total CO2e annual emission values using the updated AR5 CH4 GWP value. Each subpart II facility with existing CO2e emissions greater than the 25,000 mt CO2e threshold value are expected to continue reporting under subpart II after the AR5 CH4 GWP revision is implemented unless they are expected to have significant emissions reductions from other reported subparts. 
There are 113 facilities reporting RY2020 subpart II emissions (excluding facilities that also report to subpart Y and subpart AA). Of these, 109 reported facility emissions above 25,000 mt CO2e, and the remaining 4 reported facility emissions below 25,000 mt CO2e (and were evaluated in the previous section). Since the AR5 CH4 GWP revision will result in emissions increases under subpart II, the 109 facilities reporting above 25,000 mt CO2e will be unaffected by these changes. 
The subset of subpart II facilities that have already ceased reporting due to the off-ramp provisions between RY2014 to RY2020 were also evaluated. The AR5 CH4 GWP revision was applied to this subpart II dataset (using last reported facility emissions) to determine their assumed change in emissions. A burden increase was assumed if a facility's emissions went above the 25,000 mt CO2e threshold. 
It was determined there will be no burden increase from previously off-ramped subpart II reporters, as their emissions will stay under the 25,000 mt CO2e threshold after the updated AR5 CH4 GWP value is applied. Table 4.13-2 highlights the previously off-ramped facilities' last reported CO2e emissions using the current and revised GWP values. 
Table 4.13-2. Impact on Subpart II Off-Ramp RY CO2e Emissions
                                  Facility ID
                                  Off-Ramp RY
               Subpart II CO2e Emissions Reported in Off-Ramp RY
                Facility CO2e Emissions Reported in Off-Ramp RY
                 Revised Facility CO2e Emissions Under AR5 GWP
1009599
                                     2016
                                    11,791
                                    15,386
                                    16,801
1001671
                                     2020
                                      873
                                    22,828
                                    22,932

4.13.2.2 Analyses of Non-Reporters Entering the GHGRP 
New facilities that may be subject to reporting due to the AR5 CH4 GWP increase were assessed separately for subpart II sources at pulp and paper manufacturing, food processing, ethanol production, and petroleum refining facilities. 
Petroleum refineries were excluded from the new subpart II reporter analysis because they are required to report to subpart Y and will therefore continue reporting to subpart II. Pulp and paper manufacturing facilities were also excluded from the new reporter analysis because all pulp and paper manufacturing facilities with anaerobic treatment sources are expected to exceed the reporting requirements of 25,000 mt CO2e annually under subpart AA and will therefore continue reporting to subpart II. 
Since it is expected that only ethanol production facilities and food processing facilities may be brought into the GHGRP and there is little data that exist to estimate the population of these types of facilities, reporter burden was determined by reviewing the number of new reporters that entered the program in RY2014 following the promulgation of a new CH4 GWP in RY2013 (GWP was revised from 21 to 25). In RY2014, there was a 19% increase in the GWP (GWP revised from 21 to 25) and there were also six new subpart II reporters. These six facilities were further evaluated to determine which ones likely entered the program due to the 2013 GWP revisions. This analysis assumes that a relative increase will occur in RY2024 following a 12% increase (GWP revised from 25 to 28) in the CH4 GWP factor.
The overall new reporter impact for RY2024 was analyzed using the previous CH4 GWP revision from 21 to 25 in RY2014 to determine the impact on reporters under the new CH4 GWP revision from 25 to 28 in RY2024. The number of facilities reporting to subpart II from 2013 to 2014 increased by six following the previous GWP revision (19% increase). These facilities along with their reported subpart II and facility CO2e emissions are presented in Table 4.13-3. 
Table 4.13-3. Subpart II RY2014 New Reporting Facilities with CO2e Emissions
                                   GHGRP ID
              Type of Facility (from Reported Primary NAICS Code)
                   RY2014 Reported Subpart II CO2e Emissions
                    RY2014 Reported Facility CO2e Emissions
1004276
                       Chemical Manufacturing (Ethanol)
                                      97
                                    181,382
1007824
                                Food Processing
                                     7,275
                                    61,578
1011710
                                Food Processing
                                    20,100
                                    37,384
1011551
                                Food Processing
                                     4,798
                                    27,043
1011725
                                Food Processing
                                     4,121
                                    25,362
1011785
                                Food Processing
                                     3,762
                                     3,762

It is likely that facilities 1011710, 1011551, and 1011725 started reporting subpart II emissions to the GHGRP in RY2014 due to the previous GWP increase. It appears that facilities 1004276 and 1007824 started reporting in RY2014 because they added anaerobic processes at the facilities for RY2014. Facility 1011785 was not subject to reporting based on their reported RY2014 emissions and therefore began GHGRP reporting for reasons other than exceeding the 25,000 mt CO2e threshold. 
A 12% increase in CH4 emissions following the AR5 CH4 GWP revision is expected to result in two additional facilities in subpart II in RY2024. This was determined by the ratio of the number of new reporters in RY2014 divided by the 19% increase in the GWP in RY2014 (changing from 21 to 25) to the number of new reporters in RY2024 divided by the 12% increase in the GWP in RY2024 (changing from 25 to 28).
 4.14 Subpart OO
40 CFR part 98 subpart OO (subpart OO) is a supplier subpart that requires reporting of industrial GHG that are produced, imported, exported, or destroyed. These GHGs consist of N2O, F-GHGs, and HTFs. Many of the GHGs reported under this subpart have very high GWPs that result in high levels of CO2e from potentially small quantities of gases produced, imported, exported, or destroyed.
Facilities are subject to this subpart if they produce any amount of industrial GHGs, or import, export, or destroy the equivalent to 25,000 mt CO2e or greater. The thresholds for importing, exporting, and destroying are separate for each activity but cumulative for all gases within an activity. If a facility meets any of the activity thresholds to become subject to subpart OO, they must report all activities under the subpart.
Facilities may off-ramp from the GHGRP under the supplier provisions in 40 CFR 98.2(i)(4). A facility may cease reporting for one activity (e.g., importing) but still be required to report for a different activity (e.g., production).
Many GHGs are subject to reporting under this subpart. In addition, some GHGs may be reported to the GHGRP as "other" with a standard grouping and GWP selected by the reporter to best calculate CO2e based on the gas's chemical makeup. As such, a comprehensive list of all gases and expected GWP changes is not provided.
In addition to the AR5 GWP changes, EPA has proposed several revisions to the subpart OO rule. These include requiring reporters to provide additional documentation supporting import values and listing end users of the F-GHGs, if available. These changes will not impact the number of facilities that are required to report under this subpart.
4.14.1 Current Reporters
The first step of this analysis was to recalculate (using the revised GWPs) RY2020 quantities for GHGRP facilities that are expected to be affected by the AR5 GWP changes. These affected facilities are those with a total CO2e supplied less than (on a per-activity basis) 50,000 mt CO2e. The threshold of 50,000 mt CO2e supplied was chosen because it was believed that none of the revised GWPs will result in greater than 25,000 mt CO2e reduction in reported quantities. During the recalculation of RY2020 quantities, the analysis did confirm that no facility had an activity with reported CO2e greater than 50,000 mt CO2e and a recalculated value below 25,000 mt CO2e. The average percent change in reported CO2e supplied for GHGRP facilities was also calculated.
If step 1 concluded that subpart OO quantities from some or all facilities decreased, we then determined if these decreases will result in any facilities being eligible to off-ramp. Note that facilities may be eligible to cease reporting for one activity while still being required to report for others.
If step 1 concluded that subpart OO quantities from some or all facilities will increase, we then determined if any facilities that are in the process of off-ramping (i.e., have been reporting quantities below 25,000 mt CO2e for several years but are not yet eligible for off-ramping) may be prevented from doing so due to the GWP changes expected in RY2023. Reported quantities for RY2020 were recalculated and compared against the off-ramping thresholds. The number of facilities who would be prevented from off-ramping in the future due to the revised GWPs was determined.
The analysis found that for all activities the majority of facilities had decreased reported quantities when recalculated using the AR5 GWPs. Existing facilities may stop reporting as a result of the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2). This is calculated on a per-activity basis. Reported quantities were recalculated for RY2020 to determine if any facility would be able to count quantities at the current reported level towards the time required under the off-ramping threshold when recalculated using AR5 GWPs. The analysis found that there were no facilities whose recalculated quantities dropped them beneath the off-ramping threshold and therefore there is no change in reporting burden for current subpart OO reporters due to decreased calculated quantities using the AR5 GWPs.
The analysis found that a number of facilities had increased quantities when recalculated using the AR5 GWPs. This portion of facilities accounted for a smaller number of facilities than those whose quantities decreased, but did include facilities from all activities. The analysis recalculated RY2020 values to determine if any facilities currently reporting below 15,000 mt or 25,000 mt CO2e would exceed one of those thresholds when recalculated. Increased quantities based on the AR5 GWPs could not result in existing reporters being prevented from off-ramping.
For one facility the data rose above the off-ramping threshold based on the AR5 GWPs. This facility only reported one activity under subpart OO, and did not report under any other subpart. Therefore, one subpart OO facility will continue to report to the GHGRP as a result of the proposed revised AR5 GWPs instead of exiting the GHGRP. No other facility had recalculated quantities for any activity exceed an off-ramping threshold under the AR5 GWPs.
4.14.2 New Reporters
If step 1 of the analysis (described in Section 4.14.1) concluded that subpart OO quantities from some or all facilities will increase, we then looked at two potential results of these changes. We then determined:
 If any previously off-ramped facilities from the program will be pulled back into the program. If a facility's revised quantities are greater than 25,000 mt CO2e under the new GWPs, they are assumed to be required to begin reporting again. This was evaluated by applying the new GWPs to their most recent reported quantities to see if they will exceed the reporting threshold. This was determined using existing data reported to the program and was calculated on a per-activity basis.
 If the revised GWPs result in increased total quantities for subpart OO reporters, this may require facilities to begin reporting to the GHGRP for the first time. This would not include facilities that produce industrial GHGs as there is no threshold below which reporting is not required. For importing, exporting, and destroying, facilities with quantities less than 25,000 mt CO2e that are not also producers are not required to report. The average increase in reported GHG supplied was used to determine how many facilities would become subject to subpart OO for the first time due to the GWP revisions and thus estimating the reporting burden.
4.14.2.1 Analyses of Previously Off-Ramped Facilities 
Facilities that have previously off-ramped from the program are required to begin reporting again if their quantities exceed 25,000 mt CO2e for any activity. There have been three facilities that have previously off-ramped. This analysis recalculated the last year of reported emissions from each facility, and none of the recalculated quantities exceeded 25,000 mt CO2e for any activity. None of these facilities would be required to begin reporting again under the revised AR5 GWPs.
4.14.2.2 Analyses of Non-Reporters Entering the GHGRP 
As a number of facilities had increased quantities of GHGs reported when recalculated using the AR5 GWPs, there are potentially new reporters that will enter the program. We used reported quantities for imports, exports, and destruction to determine the magnitude and direction of change in CO2e for a representative facility based on the weighted average GWP change for all chemicals. For each chemical, the percent of all reported GHG quantities of that chemical was multiplied by the percent change in GWP to reach the weighted average change. Once this was calculated for all chemicals, the weighted percent changes were summed to calculate an overall percent change for each activity.
This average change for each activity was then used to determine if any new facilities would be required to report. If the representative facility had a decrease in GHG quantity based on the AR5 GWP changes, no new facilities would likely be required to report. If the representative facility has an increase in quantity reported using the AR5 GWPs, then the percent increase will be used to estimate the number of new facilities subject to reporting.
The representative facility had a decrease in calculated CO2e using the AR5 GWPs for each activity, so it is more likely that a facility below the reporting threshold would have recalculated quantities decrease rather than increase. Therefore, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart OO new reporters.
 4.15 Subpart QQ
40 CFR part 98 subpart QQ (subpart QQ) is a supplier subpart that requires reporting of industrial GHG, including SF6 and HFCs, that are contained in imported or exported pre-charged equipment or closed-cell foams. Electrical equipment, such as high-voltage circuit breakers, is commonly charged with SF6 for dielectric insulating and arc-quenching purposes. F-GHGs are often used as foam-blowing agents and in air conditioning systems. Many of the GHGs reported under this subpart have very high GWPs, which result in high levels of CO2e from otherwise small quantities of gases imported or exported.
Facilities are subject to this subpart if they import or export the equivalent to 25,000 mt CO2e contained within equipment or foams. The thresholds for importing and exporting are separate for each activity but cumulative for all gases within an activity. If a facility meets an activity threshold to become subject to subpart QQ, they must report both activities under the subpart.
As previously discussed, facilities may cease reporting to the GHGRP under the supplier provisions in 40 CFR 98.2(i). A facility may off-ramp for one activity (e.g., importing) but still be required to report for a different activity (e.g., exporting). Facilities and suppliers are required to notify EPA if they intend to cease reporting per any of the 40 CFR 98.2(i) provisions. 
4.15.1 Current Reporters
The first step of this analysis was to recalculate (using the revised GWPs) RY2020 quantities for GHGRP facilities that are expected to be affected by the AR5 GWP changes. These affected facilities are those with a total CO2e supplied less than (on a per-activity basis) 50,000 mt CO2e. The threshold of 50,000 mt CO2e supplied was chosen because it is believed that none of the revised GWP will result in greater than 25,000 mt CO2e reduction in reported quantities. During the recalculation of RY20 quantities, the analysis confirmed that no facility had an activity with reported CO2e greater than 50,000 mt CO2e and a recalculated value below 25,000 mt CO2e. The average percent change in reported CO2e supplied for GHGRP facilities was also calculated.
If step 1 concluded that subpart QQ quantities from some or all facilities will decrease, we then determined if these decreases result in any facilities being eligible to off-ramp (i.e., if quantities drop below 25,000 mt CO2e). Note that facilities may be eligible to cease reporting for one activity while still being required to report for the other.
If step 1 of the analysis concluded that subpart QQ quantities from some or all facilities will increase, we then determined if any facilities that are in the process of off-ramping (i.e., have been reporting quantities below 25,000 mt CO2e for several years but are not yet eligible for off-ramping) may be prevented from doing so due to the GWP changes expected in RY2023. Reported quantities for RY2020 were recalculated and compared against the off-ramping thresholds. The number of facilities that would be prevented from off-ramping in the future due to the revised GWPs was determined.
The analysis found that for both activities the majority of facilities had decreased CO2e quantities when recalculated using the AR5 GWPs. Existing facilities are eligible to off-ramp from reporting if their reported quantities are less than 25,000 mt CO2e for five consecutive years or less than 15,000 mt CO2e for three consecutive years. This is calculated on a per-activity basis. Reported quantities were recalculated for RY2020 to determine if any facility would be able to count quantities at the current reported level towards the time required under the off-ramping threshold when recalculated using AR5 GWPs. The analysis found that there were three facilities for which recalculated quantities dropped them beneath the off-ramping threshold for a reported activity.
The analysis found that a number of facilities had increased quantities when recalculated using the AR5 GWP. This portion of facilities accounted for a smaller number of facilities than those that had quantities decreased. The analysis recalculated RY2020 values to determine if any facilities currently reporting below 15,000 mt or 25,000 mt CO2e would exceed one of those thresholds when recalculated. Increased quantities based on the AR5 GWPs could result in existing reporters being prevented from off-ramping. No facilities had an increase in either import or export quantities above either the 15,000 mt or 25,000 CO2e threshold. Therefore, there is no change to the number of affected facilities due to the proposed revised AR5 GWPs for subpart QQ current reporters.
4.15.2 New Reporters
If step 1 of the analysis (described in Section 4.15.1) concluded that subpart QQ quantities from some or all facilities will increase, we then looked at two potential results of these changes. We then determined:
 If any previously off-ramped facilities from the program will be pulled back into the program. If a facility's revised quantities are greater than 25,000 mt CO2e under the new GWPs, they are assumed to be required to begin reporting again. This was evaluated by applying the new GWPs to their most recent GHGRP quantities to see if they will exceed the reporting threshold. This was determined using existing data reported to the program and was calculated on a per-activity basis.
 If the revised GWPs result in increased total quantities for subpart QQ reporters, this may require facilities to begin reporting to the GHGRP for the first time. Facilities with quantities less than 25,000 mt CO2e are not required to report. The average increase in reported GHG supplied was used to determine how many facilities would become subject to subpart QQ for the first time due to the GWP revisions.
Facilities that have previously off-ramped from the program are required to begin reporting again if their quantities exceed 25,000 mt CO2e. There has been one facility that has previously off-ramped. This analysis recalculated the last year of reported emissions and determined that the facility would not be required to restart reporting.
As a number of facilities had increased quantities of GHGs reported when recalculated using the AR5 GWPs, there are potentially new reporters that could be required to enter the program. We used reported quantities for imports and exports to determine the magnitude and direction of change in CO2e for a representative facility based on the weighted average GWP change for all chemicals. For each chemical, the percent of all reported CO 2e for that chemical was multiplied by the percent change in GWP to reach the weighted average change for that chemical. Once this was calculated for all chemicals, the weighted percent changes were summed to calculate an overall percent change for each activity.
This average change for each activity was then used to determine if any new facilities would be required to report. If the representative facility had a decrease in GHG quantity based on the AR5 GWP changes, no new facilities would likely be required to report. If the representative facility had an increase in quantity reported using the AR5 GWPs, then the percent increase would be used to estimate the number of new facilities subject to reporting.
The representative facility had a decrease in calculated CO2e using the AR5 GWPs for both activities, so it is more likely that a facility below the reporting threshold would have recalculated quantities decrease rather than increase. Therefore, this analysis determined that the AR5 GWP revisions will not result in a change to the number of affected facilities for subpart QQ new reporters.
 4.16 Subpart SS
40 CFR part 98, subpart SS (subpart SS) currently requires reporting of GHG emissions from facilities that manufacture, install, and/or refurbish electrical equipment that contain SF6 and PFCs (40 CFR 98.450). Under the current rule, any facility in this source category that has combined annual purchases of SF6 and PFCs greater than 23,000 lbs in a calendar year must begin reporting emissions from equipment testing, installation, manufacturing of new equipment, decommissioning and refurbishing of old equipment, and gas storage. This includes emissions from equipment that is installed at an off-site electric power transmission or distribution location if the emissions occur before the title to the equipment is transferred to the electric power transmission or distribution entity. Five facilities are currently subject to subpart SS. Two other facilities were subject to reporting in prior years but have since exited the GHGRP. All subpart SS facilities reported emissions of SF6 and only one facility has reported emissions of a PFC (perfluoromethane (PFC-14)) to date. The emissions of SF6 make up over 99% of all emissions reported to the GHGRP for this source category.
In addition to reporting SF6 and PFC emissions, some subpart SS facilities have fossil fuel-fired combustion units. The combustion emissions are generally low but must be reported in accordance with the provisions of subpart C. Three of the five subpart SS facilities that reported in RY2020 also reported combustion emissions under subpart C (40 CFR 98.451). 
EPA has proposed updating the GWPs in Table A-1 to subpart A. The GWP changes expected to affect subpart SS emissions are shown in Table 4.16-1.
            Table 4.16-1. Applicable GWP Changes for Subpart SS[a]
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
SF6
22,800
23,500
Increase
PFC-14 (perfluoromethane)
7,390
6,630
Decrease
[a] GWPs for combustion emissions (CH4, N2O) also have been revised in AR5. The facility-level CO2e calculations discussed later in this memorandum include the proposed changes to the GWPs for CH4 and N2O. 
In addition to the GWP changes, EPA proposed several changes to subpart SS to improve the accuracy of emissions reported and enhance the overall quality of the data collected under the GHGRP (87 FR 36920, June 21, 2022). The changes were proposed because of the recent development of replacement insulating gases that have much lower GWPs than SF6 or PFCs. These replacement gases include dry air and F-GHGs. Table 4.16-2 lists the alternative gases currently available to manufacturers, the composition of the mixtures used, and their GWPs. Unlike SF6 which is used without dilution, the new F-GHGs are used in mixtures with CO2, oxygen, and/or nitrogen. The resulting GWP of the gas mixtures are significantly lower than SF6. In the last three years, several manufacturers have designed and begun marketing new products incorporating these alternative low GWP gases, while other manufacturers have developed products that use a vacuum or dry air mixture (see Table 4.16-2) as insulator. The F-GHGs have begun to be used in Europe and we expect their use to increase in the United States in future years. For this reason, the proposed amendments expand reporting to include emissions of any F-GHGs used by manufacturers. By collecting data on the types, composition and emissions of these new gases, EPA will gain a better understanding of emission trends and will be able to account for the total emissions from this sector.
Table 4.16-2. Composition of Alternative Gases Currently Available for Electric Equipment Manufacturers
                                Characteristics
                                    Dry Air
                               CF4-Fluoronitrile
                               CF5-Fluoroketone
Chemical Formula
N2 and O2
(CF3)2CFCN
(CF3)2CFC(O)CF3
100 Year GWP of Gas
0
2,100
<1
Typical Composition of Mixture
70  -  80% N2
20  -  30% O2
3  -  5% (CF3)2CFCN
95  -  97% CO2 and O2
10% (CF3)2CFC(O)CF3
90% mixture of O2 and N2, or CO2
100 Year GWP of Mixture
0
<500
<1

With the potential for alternate gases to become more widely used, EPA is proposing to revise the current applicability threshold to account for these lower GWP gases. As we previously noted, the current rule is applicable to a facility that purchases more than 23,000 pounds of combined SF6 and PFCs in a calendar year. This threshold is an "equivalent threshold" to the 25,000 mt CO2e threshold. This threshold was developed using the GWP of SF6 (set at 23,900 in 2010) and an emission factor of 10%. The 10% emission factor was based on the average of "ideal" and "realistic" manufacturing emission rates (4% and 17%, respectively) identified in a paper prepared by the International Council on Large Electric Systems (CIGRE) in February 2002. The proposal replaces the current applicability threshold with an equation that potential new reporters would use to calculate emissions from all F-GHGs by multiplying the total annual purchases of each insulating gas by the fraction of F-GHG in the insulating gas, the GWP for each F-GHG, and the emission factor of 0.10 (or 10%). The results would be summed for all F-GHGs used to calculate a total applicability CO2e for subpart SS. The proposed changes also include moving this source category to Table A-4 to subpart A, which will require the potential reporter to add the emissions from any fossil fuel-fired combustion units operated at their facility. If the total CO2e calculated exceeds 25,000 mt CO2e, the facility would become subject to the GHGRP beginning in the year they first exceed the reporting threshold. 
The proposed revised applicability threshold is based on a new Equation SS-1, which accounts for the GWP of gases used and estimates potential emissions from the source. Under the proposed changes, combustion emissions would also be included in the facility emissions when determining whether a facility has exceeded the proposed 25,000 mt CO2e applicability threshold. The actual subpart SS emissions are calculated annually using a mass-balance equation provided in the rule and may be significantly lower than the applicability emissions where a facility has implemented emission reduction practices. The mass-balance approach used to calculate emissions is retained in the proposal, although the facility would be required to calculate and report emissions of other F-GHGs as discussed above.
4.16.1 Current Reporters
Subpart SS has two facilities currently in the process of off-ramping (i.e., below 25,000 mt CO2e for RY2020). For these facilities, we used their emissions from their last report to recalculate their CO2e using the AR5 GWPs. The recalculated CO2e was then compared with the 25,000 mt threshold. If the facility's recalculated CO2e exceeded 25,000 mt, then the facility would be required to continue reporting. 
The CO2e for all facilities reporting under subpart SS were recalculated using the reported emissions for RY2020 and the new GWPs for SF6 and PFC-14. As no other gases have been reported under this subpart, these are the only changes in subpart SS CO2e that would result from the proposed adoption of the AR5 GWPs. Three of these facilities also report emissions under subpart C; the CO2e for the combustion emissions were also recalculated using the AR5 GWPs and included in the total facility-wide CO2e for each facility. The overall CO2e for each facility increased by between 461.8 and 2,304 mt, or 1.9 to 3.1%. 
Of the five facilities reporting emissions under subpart SS in RY2020, two reported facility-wide CO2e of less than 25,000 mt CO2e (including combustion sources reported under subpart C). The reported and recalculated CO2e for these facilities (1006009 and 1009615) for the past five years are shown in Table 4.16-3.
     Table 4.16-3. Recalculated CO2e from Potential Off-Ramping Facilities
                                   Facility
                                      GWP
                                    RY2016
                                    RY2017
                                    RY2018
                                    RY2019
                                    RY2020
1006009
22,800
4,550
6,495
4,468
15,042
11,025

23,500
4,690
6,694
4,605
15,504
11,363
1009615
22,800
50,265
58,730
36,093
24,536
20,461

23,500
51,559
60,289
36,929
25,015
20,858

Based on the recalculated CO2e (including subpart C for the three facilities operating fossil fuel-fired combustion units), these facilities would still qualify to cease reporting and would not be required to recommence reporting in future years if their emissions remain consistent with those reported in RY2020. Facility 1009615 has only one year of CO2e less than 25,000 mt and will be required to report for at least three more years (four years if the next three years are between 15,000 and 24,999 mt CO2e). Based on internet research, it does not appear that facility 1009615 manufactures equipment using the new F-GHG insulating gases. 
Facility 1006009 has reported five consecutive years of CO2e less than 25,000 mt and is currently eligible to cease reporting beginning in RY2021. This facility currently markets electric equipment using the new insulating gas CF5-fluoroketone discussed in Section 1.0. We do not know whether this facility emits CF5-fluoroketone. However, if they emit CF5-fluoroketone, we expect the CO2e contributed by the emissions of this F-GHG to be small relative to the CO2e from SF6 emissions because the GWP for CF5-fluoroketone is less than 1. Based on this facility's relatively low emissions (11,024 mt CO2e in RY2020) and the low GWP for CF5-fluoroketone, it is unlikely that the proposed reporting of CF5-fluoroketone emissions would cause this facility to exceed the 25,000 mt CO2e threshold that would require them to recommence reporting in the future if the proposed changes are adopted. 
4.16.2 New Reporters
In this analysis, we determined the impact of the proposed use of AR5 GWPs and the proposed reporting of new F-GHGs for potential new reporters. We recalculated the CO2e for each facility that reported in RY2020 using the emissions they reported and the AR5 GWPs. 
Subpart SS has one previous reporter that qualified to off-ramp from reporting in 2016. Like the facilities that are currently in the process of meeting the off-ramp provisions, we used the facility's emissions from their last report in 2016 to recalculate their CO2e using the AR5 GWPs. The recalculated CO2e was then compared with the 25,000 mt threshold. If the facility's recalculated CO2e exceeded 25,000 mt, then the facility would be required to begin reporting again.
Facility 1010764 last reported subpart SS emissions in RY2016 and reported only emissions of SF6. We recalculated the CO2e using the emissions reported in RY2016 and the AR5 GWP for SF6. The recalculated CO2e for this facility was 571 mt, thus the facility would not be required to begin reporting again if the AR5 GWP for SF6 is adopted. Based on our review of the company's website, it appears that they have developed SF6-free equipment using a mixture of nitrogen and oxygen. Since these gases are not greenhouse gases, we do not expect this facility will be required to recommence reporting due to the proposed changes. 
We also evaluated whether the proposed changes would cause any new facility to begin reporting for the first time. To determine whether any new facilities would be required to report if the proposed changes are adopted, we used the proposed Equation SS-1 and the AR5 GWP for SF6 to calculate the CO2e for a facility using only SF6, purchasing 23,000 lbs of gas in a calendar year (i.e., the volume of gas used for the current applicability), and having no combustion units. We then assessed whether CO2e from combustion emissions and other F-GHGs, when added to the CO2e from SF6 would be likely to result in a facility-wide CO2e exceeding the proposed 25,000 mt applicability threshold. For the combustion emissions, we evaluated the CO2e reported by the three existing reporters that report under subparts C and SS to determine a typical range for the CO2e from combustions as a percentage of subpart SS CO2e. 
Finally, we considered the impact of the new F-GHG insulating gases on applicability. We conducted internet searches to identify the alternative gases currently marketed. These gases are primarily being developed due to the high GWP of SF6. We used the National Electrical Manufacturers Association (NEMA) to identify manufacturers that currently market electrical equipment using one or more of the alternative gases listed in Table 4.16-2. NEMA has an SF6 alternatives coalition comprised of manufacturers, support companies, and utilities. Using this list of manufacturers, we researched their product lines to better understand the types of products companies are currently marketing. We then assessed whether companies using these other F-GHGs would be likely to become subject to subpart SS due to the proposed changes to the applicability criteria.
The potential for new facilities to be required to report under subpart SS due to the proposed revisions was also assessed. Using the proposed Equation SS-1, proposed GWP of 23,500 for SF6, and 23,000 lbs of purchased gas (the current applicability threshold), the estimated emissions calculated for comparison to the applicability threshold using Equation SS-1 are 24,517 mt CO2e. Thus, the current applicability threshold in this case is lower than the proposed applicability threshold. 
A facility that has fossil fuel-fired combustion units would become subject to reporting if the CO2e from combustion emissions combined with the CO2e calculated using proposed Equation SS-1 exceeds 25,000 mt. Therefore, it is possible for a facility that has always purchased less than 23,000 lbs of SF6 and PFCs to become subject to the GHGRP due to the proposed changes. However, for existing subpart SS reporters, the combustion emissions are much smaller than the applicability emissions calculated using proposed Equation SS-1. Table 4.16-4 shows the calculated applicability emissions and combustion emissions for each of the three facilities that have combustion units. The CO2e values shown in Table 4.16-4 were calculated using the AR5 GWPs, purchase records reported under subpart SS, and subpart C emissions data reported in RY2020.
      Table 4.16-4. Applicability Emissions from Eq. SS-1 and Combustion
                                   Facility
                              Eq. SS-1
Emissions
                             Combustion Emissions
                 Combustion Emissions as Percent of Total CO2e
1009613
77,832
541
0.7
1009615
52,251
7,534
12.6
1000039
133,313
168
0.1

Considering the worst-case scenario of a facility with SF6 purchases that are currently just below the 23,000 lbs applicability threshold, the facility would need combustion emissions equivalent to 483 mt CO2e (approximately 2% of total CO2e) to be subject to the reporting rule if the proposed changes are adopted. While the CO2e from combustion sources can be as high as 12.6% of the total CO2e, the CO2e from combustion for two of the five subpart SS reporters accounts for less than 1% of their total CO2e. The two other subpart SS reporters have no combustion units. Compared with the other subpart SS facilities, combustion emissions reported by 1009615 are significantly higher than reported by other facilities in this sector and are likely not representative of this sector. While it is possible a facility could become subject to the GHGRP due the proposed GWP changes and inclusion of their combustion emissions, we consider it unlikely because (1) not all equipment manufactures operate fossil fuel-fired combustion units, and (2) those manufactures that operate fossil fuel-fired combustion units typically report relatively low-levels of combustion emissions. 
Using the membership list for NEMA's SF6 alternatives coalition, we identified companies that manufacture electrical equipment. Based on internet research, a number of the companies we identified are in the process of developing and/or marketing equipment that uses alternative gases, including three who are currently not reporting under subpart SS. We assessed whether any of these companies may potentially become subject to subpart SS for the first time due to the proposed changes to the applicability criteria. We were not able to determine the amount of F-GHGs currently used by each company or confirm the company is using F-GHGs at their manufacturing facilities in the United States. However, all of these companies are also marketing equipment containing SF6. 
Although the use of alternative gases, such as CF4-fluoronitrile and CF5-fluoroketone, is expected to increase over the next few years, we do not expect them to have a significant impact on the number of facilities required to report to the GHGRP over the next three years. First, the adoption of these new gases by utilities is likely to be slow due to the limited range of products currently marketed and the long lifetime of existing electrical equipment (typically over 40 years). Second, the alternative gases are used in dilute mixtures that have GWPs that are significantly lower than SF6. As we noted earlier, we know of two new F-GHGs that have begun to be used in electrical equipment. CF4-fluoronitrile has a GWP of 2,100 and CF5-fluoroketone has a GWP of less than 1. These F-GHGs are mixed with dry air, nitrogen, or CO2 to produce the insulating gas used in electric equipment, which reduces the GWP of the insulating gas as-used to less than 500 for dilute mixtures of CF4-fluoronitrile with CO2 and O2 and less than 1 for dilute mixtures of CF5-fluoroketone with O2 and nitrogen, or CO2. Assuming a 10% emission rate, a facility that uses 1 mt of SF6 would have emissions equivalent to 2,350 mt CO2e (based on a GWP of 23,500). A facility that uses a 5% solution of CF4-fluoronitrile would need to purchase 940 mt of gas to have emissions equivalent to 2,350 mt CO2e, assuming a GWP of 500 and the same 10% emission rate. Third, some of the companies we identified have developed products that rely on a vacuum or dry air as insulator. 
For those manufacturers that are using CF4-fluoronitrile or CF5-fluoroketone in some of their products, we expect the combined effect of the small fraction of F-GHG used in each product, their inherently low GWPs compared with SF6, and the relatively low number of units currently manufactured to result in insignificant levels of CO2e compared with the CO2e for SF6 emissions. We expect the use of alternative F-GHGs will slowly increase over the next few years. Emissions of SF6 for many of the facilities in this sector may slowly decline as equipment using alternative insulating gases gradually gain market share.
 4.17 Subpart TT
40 CFR part 98 subpart TT (subpart TT) requires reporting of GHG emissions produced by industrial waste landfills that accept waste from various industry sectors. CO2 generated from waste decomposition is considered biogenic and N2O emissions generated for waste decomposition are negligible; thus, subpart TT requires facilities to report the generated CH4 emissions from industrial waste landfills.
For subpart TT, the GWP changes shown in Table 4.17-1 are expected to affect reported emissions:
Table 4.17-1. Applicable GWP Change for Subpart TT
                                      GHG
                                  Current GWP
                                    AR5 GWP
                                    Change
                                      CH4
                                      25
                                      28
                                   Increase

Subpart TT applies to industrial waste landfills that accepted waste on or after January 1, 1980, are located at a facility with a total landfill design capacity greater than or equal to 300,000 mt, and with combined emissions from all applicable subparts in the GHGRP of 25,000 mt CO2e or more per year. Most facilities report to subpart TT because their manufacturing emissions (e.g., process CO2 emissions) and/or combustion GHG emissions exceed 25,000 mt CO2e rather than their subpart TT emissions, that is, the magnitude of their subpart TT emissions does not influence whether they report or not. Therefore, the GHG emissions from the entire facility must be evaluated to determine the applicability of subpart TT for industrial waste landfills. 
Because the GWP for CH4 is increasing, emissions at subpart TT facilities will have an overall increase. The approach to evaluating burden to subpart TT under the AR5 CH4 GWP revision is presented for:
 Facilities that met the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2) as of RY2020, 
 Facilities that are projected to cease reporting prior to RY2023 due to the off-ramp provisions, but are brought back into the program in RY2023 with the new AR5 CH4 GWP, and 
 Facilities that are required to start reporting to the GHGRP for the first time after the GWP revision is adopted. 
This analysis assumes that the AR5 CH4 GWP revision will be incorporated for RY2023 for active and off-ramped reporters and for RY2024 for new reporters. A summary of the industrial sector contributors to industrial landfill waste facilities is shown in Table 4.17-2.
Table 4.17-2. RY2020 Subpart TT Industrial Sector Contributors 
              Type of Facility (from Reported Primary NAICS Code)
                           All Subparts Reported To
                Included/Excluded within the Burden Evaluation
                       Number of TT Reporting Facilities
                              Paper Manufacturing
                               C, AA, II, PP, TT
                                   Excluded
                                      88
                         Waste Treatment and Disposal
                                   C, HH, TT
                                   Included
                                      15
                            Chemical Manufacturing
                              C, D, L, X, OO, TT
                                   Excluded
                                       8
                 Sugar and Confectionery Product Manufacturing
                                   C, S, TT
                                   Excluded
                                       8
                                   Foundries
                                   C, N, TT
                                   Excluded
                                       7
               Iron and Steel Mills and Ferroalloy Manufacturing
                                   C, Q, TT
                                   Excluded
                                       6
Resin, Synthetic Rubber, and Artificial and Synthetic Fibers and Filaments Manufacturing
                               C, E, P, V, X, TT
                                   Excluded
                                       5
           Electric Power Generation, Transmission, and Distribution
                                   C, D, TT
                                   Excluded
                                       5
                Alumina and Aluminum Production and Processing
                                   C, F, TT
                                   Excluded
                                       5
                   Petroleum and Coal Products Manufacturing
                                C, P, Y, MM, TT
                                   Excluded
                                       4
                                  Paper Mills
                                   C, AA, TT
                                   Excluded
                                       3
                              Food Manufacturing
                                     C, TT
                                   Included
                                       3
                         Basic Chemical Manufacturing
                              C, O, W, X, DD, TT
                                   Excluded
                                       3
                               Metal Ore Mining
                                     C, TT
                                   Included
                                       1
          Veneer, Plywood, and Engineered Wood Product Manufacturing
                                     C, TT
                                   Included
                                       1
                            Beverage Manufacturing
                                     C, TT
                                   Included
                                       1
                               Sugarcane Farming
                                     C, TT
                                   Included
                                       1
                             Forging and Stamping
                                     C, TT
                                   Included
                                       1
                   Pharmaceutical and Medicine Manufacturing
                                     C, TT
                                   Included
                                       1

We determined that the AR5 CH4 GWP change will not significantly change emissions, or the reporting applicability of the facility types listed as "Excluded" in Table 4.17-2. Industrial waste landfills are generally co-located at facilities that report to the GHGRP due to meeting other subpart-specific reporting criteria and are primarily driven by process level CO2 emissions and/or combustion emissions from other subparts. The AR5 CH4 GWP increase for subpart C (and any other subparts using subpart C combustion factors) was determined to be offset by the AR5 N2O decrease, resulting in negligible changes in subpart C emissions (and combustion in other subparts using the C methodology) as discussed in Section 2.2. 
CH4 emissions increases from subpart TT sources at facilities listed as "Excluded" in Table 4.17-2 were reviewed and determined to be negligible, as these facilities emissions are driven by other industrial activities. This analysis assumes that no new reporters will enter the GHGRP from these industrial categories because of the AR5 CH4 GWP change in subpart TT. For these industrial sectors, the burden analysis was limited to evaluating the impacts to facilities that have already ceased reporting, or that are projected to cease reporting due to the off-ramp provisions. 
For the remaining TT industrial categories (i.e., those listed as "Included" in Table 4.17-2), an analysis was performed to estimate the number of facilities expected to start reporting for the first time, as well as the impacts to off-ramped (including those projected to) facilities.
There are 55 facilities reporting RY2020 subpart TT emissions after omitting facilities that are listed as "Excluded" in Table 4.17-2. Of the 55 facilities, 47 facilities reported facility emissions above 25,000 mt CO2e, and the remaining 8 reported facility emissions below 25,000 mt CO2e. Since the AR5 CH4 GWP revision will result in emissions increases under subpart TT, the 47 facilities reporting above 25,000 mt CO2e will be unaffected by these changes. The remaining 8 were further evaluated, as discussed below.
4.17.1 Current Reporters
For this analysis, projected off-ramp facilities are defined as those that are assumed to cease reporting prior to RY2023. To determine this group of facilities, RY2021 and RY2022 emissions were estimated using past reported data for applicable subpart TT facilities. Additionally, the variability of prior year data was reviewed to determine if emissions were consistent or inconsistent. For cases where prior year (RY2016 - RY2020) emissions were consistently below the off-ramp provisions in 40 CFR 98.2(i)(1) and 98.2(i)(2) and the facility is eligible to cease reporting for the first time in either RY2021 or RY2022, it was assumed that these facilities will cease reporting prior to RY2023. This subset of facilities was then evaluated to determine if the subpart TT CH4 GWP increase in RY2023 would raise emissions over the 25,000 mt CO2e threshold. If this is true, then the facility was assumed to incur burden because they would be brought back into the program.
Of the eight facilities with existing emissions below 25,000 mt CO2e, four facilities were projected to off-ramp prior to RY2023 because their facility emissions were consistent over the past five years, and they will be off-ramp eligible for the first time prior to RY2023 (as defined above). The AR5 CH4 GWP was applied to these four facilities, and it was determined through re-calculations that the four facilities would not be brought back into the program because the recalculated emissions will not exceed the 25,000 mt CO2e threshold. The other four facilities are still projected to report to the GHGRP as they are not eligible to off-ramp prior to RY2023. Thus, there is no change to the number of affected facilities for subpart TT.
4.17.2 New Reporters
4.17.2.1 Analyses of Previously Off-Ramped Facilities 
Subpart TT facilities that have already ceased reporting due to the off-ramp provisions between RY2014 to RY2020 were also evaluated. The AR5 CH4 GWP revision was applied to all previously off-ramped subpart TT facilities (using last reported facility emissions) to determine their assumed change in emissions. A burden increase was assumed if a facility's emissions went above the 25,000 mt CO2e threshold under the updated AR5 CH4 GWP. 
Table 4.17-3 highlights the off-ramped reporting facilities' last reported emissions using the current and revised GWP values. It was determined that there are no previously off-ramped reporters that will need to start reporting again because of the GWP changes.
Table 4.17-3. Impact on Subpart TT Off-Ramp RY CO2e Emissions
                                  Facility ID
                                  Off-Ramp RY
               Subpart TT CO2e Emissions Reported in Off-Ramp RY
                Facility CO2e Emissions Reported in Off-Ramp RY
                 Revised Facility CO2e Emissions Under AR5 GWP
                                    1006522
                                     2014
                                     1,084
                                     1,084
                                     1,214
                                    1010668
                                     2014
                                    10,909
                                    10,909
                                    12,218
                                    1006679
                                     2015
                                     2,362
                                     2,362
                                     2,645
                                    1008069
                                     2015
                                     8,698
                                     8,698
                                     9,742
                                    1009526
                                     2017
                                     3,876
                                     4,776
                                     5,242
                                    1009824
                                     2017
                                    20,389
                                    20,389
                                    22,835

4.17.2.2 Analyses of Non-Reporters Entering the GHGRP 
Since very little data exists to estimate the population of facilities that may be required to start reporting to the GHGRP for the first time after the GWP revision is adopted, reporter burden was determined by reviewing the number of new reporters that entered the program in RY2014 following the promulgation of a new CH4 GWP in RY2013 (GWP was revised from 21 to 25). In RY2014, there was a 19% increase in the GWP (GWP revised from 21 to 25) and there were also three new subpart TT reporters (see Table 4.17-4). This analysis assumes that a relative increase in facilities will also occur in RY2024 following a 12% increase (GWP revised from 25 to 28) in the CH4 GWP factor.
The three new facilities were further evaluated to determine which ones likely entered the program due to the 2013 GWP revisions. It is likely that facility 1009526 started reporting subpart TT emissions to the GHGRP in RY2014 due to the 2013 GWP increase. Facility 1011501 started reporting in RY2014 because of a change in landfill ownership. It was not clear why facility 1011740 started reporting but based on the total facility emissions and the contribution of TT, it is unlikely that this facility started reporting due to the GWP increase. As such, it is assumed that one new facility started reporting due to the 2013 GWP revisions. 
A 12% increase in CH4 emissions following the AR5 CH4 GWP revision is expected to result in one additional facility reporting to subpart TT in RY2024. This was determined by ratioing the number of new reporters in RY2014 (one new reporter was assumed to enter the program from the 19% increase in the GWP in RY2014) to the percent increase in RY2024 of 12% (GWP changing from 25 to 28).
Table 4.17-4. Subpart TT RY2014 New Reporting Facilities with CO2e Emissions
                                   GHGRP ID
              Type of Facility (from Reported Primary NAICS Code)
                   RY2014 Reported Subpart TT CO2e Emissions
                    RY2014 Reported Facility CO2e Emissions
1011501
Waste Treatment and Disposal
353,145
353,153
1011740
Pharmaceutical and Medicine Manufacturing
14,925
50,307
1009526
All Other Electrical Equipment and Component Manufacturing
4,289
28,156
 
 Appendix A: Proposed Revised Chemical-Specific GWPs for Compounds in Table A-1
                                     Name
                                    CAS No.
                               Chemical Formula
                  Current Global
Warming
Potential
(100 Yr.)
                  Proposed Global
Warming
Potential
(100 Yr.)
                            Chemical-Specific GWPs
Carbon dioxide
124-38-9
CO2
1
1
Methane
74-82-8
CH4
25
28
Nitrous oxide
10024-97-2
N2O
298
265
                            Fully Fluorinated GHGs
Sulfur hexafluoride
2551-62-4
SF6
22,800
23,500
Trifluoromethyl sulfur pentafluoride
373-80-8
SF5CF3
17,700
17,400
Nitrogen trifluoride
7783-54-2
NF3
17,200
16,100
PFC-14 (Perfluoromethane)
75-73-0
CF4
7,390
6,630
PFC-116 (Perfluoroethane)
76-16-4
C2F6
12,200
11,100
PFC-218 (Perfluoropropane)
76-19-7
C3F8
8,830
8,900
Perfluorocyclopropane
931-91-9
c-C3F6
17,340
9,200
PFC-3-1-10 (Perfluorobutane)
355-25-9
C4F10
8,860
9,200
PFC-318 (Perfluorocyclobutane)
115-25-3
c-C4F8
10,300
9,540
Perfluorotetrahydrofuran
773-14-8
c-C4F8O
10,000*
13,900
PFC-4-1-12 (Perfluoropentane)
678-26-2
C5F12
9,160
8,550
PFC-5-1-14 (Perfluorohexane, FC-72)
355-42-0
C6F14
9,300
7,910
PFC-6-1-12
335-57-9
C7F16; CF3(CF2)5CF3
7,820
7,820
PFC-7-1-18
307-34-6
C8F18; CF3(CF2)6CF3
7,620
7,620
PFC-9-1-18
306-94-5
C10F18
7,500
7,190
PFPMIE (HT-70)
NA
CF3OCF(CF3)CF2OCF2OCF3
10,300
9,710
Perfluorodecalin (cis)
60433-11-6
Z-C10F18
7,236
7,240
Perfluorodecalin (trans)
60433-12-7
E-C10F18
6,288
6,290
Perfluorotriethylamine
359-70-6
N(C2F5)3
10,000*
10,300
Perfluorotripropylamine
338-83-0
N(CF2CF2CF3)3
10,000*
9,030
Perfluorotributylamine
311-89-7
N(CF2CF2CF2CF3)3
10,000*
8,490
Perfluorotripentylamine
338-84-1
N(CF2CF2CF2CF2CF3)3
10,000*
7,260
  Saturated Hydrofluorocarbons (HFCs) With Two or Fewer Carbon-Hydrogen Bonds
(4s,5s)-1,1,2,2,3,3,4,5-octafluorocyclopentane
158389-18-5
trans-cyc (-CF2CF2CF2CHFCHF-)
3,700*
258
HFC-23
75-46-7
CHF3
14,800
12,400
HFC-32
75-10-5
CH2F2
675
677
HFC-125
354-33-6
C2HF5
3,500
3,170
HFC-134
359-35-3
C2H2F4
1,100
1,120
HFC-134a
811-97-2
CH2FCF3
1,430
1,300
HFC-227ca
2252-84-8
CF3CF2CHF2
2,640
2,640
HFC-227ea
431-89-0
C3HF7
3,220
3,350
HFC-236cb
677-56-5
CH2FCF2CF3
1,340
1,210
HFC-236ea
431-63-0
CHF2CHFCF3
1,370
1,330
HFC-236fa
690-39-1
C3H2F6
9,810
8,060
HFC-329p
375-17-7
CHF2CF2CF2CF3
2,360
2,360
HFC-43-10mee
138495-42-8
CF3CFHCFHCF2CF3
1,640
1,650
 Saturated Hydrofluorocarbons (HFCs) With Three or More Carbon-Hydrogen Bonds
1,1,2,2,3,3-hexafluorocyclopentane
123768-18-3
cyc (-CF2CF2CF2CH2CH2-)
930*
120
1,1,2,2,3,3,4-heptafluorocyclopentane
15290-77-4
cyc (-CF2CF2CF2CHFCH2-)
930*
231
HFC-41
593-53-3
CH3F
92
116
HFC-143
430-66-0
C2H3F3
353
328
HFC-143a
420-46-2
C2H3F3
4,470
4,800
HFC-152
624-72-6
CH2FCH2F
53
16
HFC-152a
75-37-6
CH3CHF2
124
138
HFC-161
353-36-6
CH3CH2F
12
4
HFC-245ca
679-86-7
C3H3F5
693
716
HFC-245cb
1814-88-6
CF3CF2CH3
4,620
4,620
HFC-245ea
24270-66-4
CHF2CHFCHF2
235
235
HFC-245eb
431-31-2
CH2FCHFCF3
290
290
HFC-245fa
460-73-1
CHF2CH2CF3
1,030
858
HFC-263fb
421-07-8
CH3CH2CF3
76
76
HFC-272ca
420-45-1
CH3CF2CH3
144
144
HFC-365mfc
406-58-6
CH3CF2CH2CF3
794
804
Saturated Hydrofluoroethers (HFEs) and Hydrochlorofluoroethers (HCFEs) With One Carbon-Hydrogen Bond
HFE-125
3822-68-2
CHF2OCF3
14,900
12,400
HFE-227ea
2356-62-9
CF3CHFOCF3
1,540
6,450
HFE-329mcc2
134769-21-4
CF3CF2OCF2CHF2
919
3,070
HFE-329me3
428454-68-6
CF3CFHCF2OCF3
4,550
4,550
1,1,1,2,2,3,3-Heptafluoro-3-(1,2,2,2-tetrafluoroethoxy)-propane
3330-15-2
CF3CF2CF2OCHFCF3
6,490
6,490
            Saturated HFEs and HCFEs With Two Carbon-Hydrogen Bonds
HFE-134 (HG-00)
1691-17-4
CHF2OCHF2
6,320
5,560
HFE-236ca
32778-11-3
CHF2OCF2CHF2
4,240
4,240
HFE-236ca12 (HG-10)
78522-47-1
CHF2OCF2OCHF2
2,800
5,350
HFE-236ea2 (Desflurane)
57041-67-5
CHF2OCHFCF3
989
1,790
HFE-236fa
20193-67-3
CF3CH2OCF3
487
979
HFE-338mcf2
156053-88-2
CF3CF2OCH2CF3
552
929
HFE-338mmz1
26103-08-2
CHF2OCH(CF3)2
380
2,620
HFE-338pcc13 (HG-01)
188690-78-0
CHF2OCF2CF2OCHF2
1,500
2,910
HFE-43-10pccc (H-Galden 1040x, HG-11)
E1730133
CHF2OCF2OC2F4OCHF2
1,870
2,820
HCFE-235ca2 (Enflurane)
13838-16-9
CHF2OCF2CHFCl
583
583
HCFE-235da2 (Isoflurane)
26675-46-7
CHF2OCHClCF3
350
491
HG-02
205367-61-9
HF2C-(OCF2CF2)2-OCF2H
3,825
2,730
HG-03
173350-37-3
HF2C-(OCF2CF2)3-OCF2H
3,670
2,850
HG-20
249932-25-0
HF2C-(OCF2)2-OCF2H
5,300
5,300
HG-21
249932-26-1
HF2C-OCF2CF2OCF2OCF2O-CF2H
3,890
3,890
HG-30
188690-77-9
HF2C-(OCF2)3-OCF2H
7,330
7,330
1,1,3,3,4,4,6,6,7,7,9,9,10,10,12,12,13,13,15,15-eicosafluoro-2,5,8,11,14-Pentaoxapentadecane
173350-38-4
HCF2O(CF2CF2O)4CF2H
3,630
3,630
1,1,2-Trifluoro-2-(trifluoromethoxy)-ethane
84011-06-3
CHF2CHFOCF3
1,240
1,240
Trifluoro(fluoromethoxy)methane
2261-01-0
CH2FOCF3
751
751
       Saturated HFEs and HCFEs With Three or More Carbon-Hydrogen Bonds
HFE-143a
421-14-7
CH3OCF3
756
523
HFE-245cb2
22410-44-2
CH3OCF2CF3
708
654
HFE-245fa1
84011-15-4
CHF2CH2OCF3
286
828
HFE-245fa2
1885-48-9
CHF2OCH2CF3
659
812
HFE-254cb2
425-88-7
CH3OCF2CHF2
359
301
HFE-263fb2
460-43-5
CF3CH2OCH3
11
1
HFE-263m1; R-E-143a
690-22-2
CF3OCH2CH3
29
		29
HFE-347mcc3 (HFE-7000)
375-03-1
CH3OCF2CF2CF3
575
530
HFE-347mcf2
171182-95-9
CF3CF2OCH2CHF2
374
854
HFE-347mmy1
22052-84-2
CH3OCF(CF3)2
343
363
HFE-347mmz1 (Sevoflurane)
28523-86-6
(CF3)2CHOCH2F
216
216
HFE-347pcf2
406-78-0
CHF2CF2OCH2CF3
580
889
HFE-356mec3
382-34-3
CH3OCF2CHFCF3
101
387
HFE-356mff2
333-36-8
CF3CH2OCH2CF3
17
17
HFE-356mmz1
13171-18-1
(CF3)2CHOCH3
27
14
HFE-356pcc3
160620-20-2
CH3OCF2CF2CHF2
110
413
HFE-356pcf2
50807-77-7
CHF2CH2OCF2CHF2
265
719
HFE-356pcf3
35042-99-0
CHF2OCH2CF2CHF2
502
446
HFE-365mcf2
22052-81-9
CF3CF2OCH2CH3
58
58
HFE-365mcf3
378-16-5
CF3CF2CH2OCH3
11
0.99
HFE-374pc2
512-51-6
CH3CH2OCF2CHF2
557
627
HFE-449s1 (HFE-7100) Chemical blend
163702-07-6
C4F9OCH3
297
421
 
163702-08-7
(CF3)2CFCF2OCH3

HFE-569sf2 (HFE-7200) Chemical blend
163702-05-4
C4F9OC2H5
59
57
 
163702-06-5
(CF3)2CFCF2OC2H5

HFE-7300
132182-92-4
(CF3)2CFCFOC2H5CF2CF2CF3
270*
405
HFE-7500
297730-93-9
n-C3F7CFOC2H5CF(CF3)2
270*
13
HG'-01
73287-23-7
CH3OCF2CF2OCH3
222
222
HG'-02
485399-46-0
CH3O(CF2CF2O)2CH3
236
236
HG'-03
485399-48-2
CH3O(CF2CF2O)3CH3
221
221
Difluoro(methoxy)methane
359-15-9
CH3OCHF2
144
144
2-Chloro-1,1,2-trifluoro-1-methoxyethane
425-87-6
CH3OCF2CHFCl
122
122
1-Ethoxy-1,1,2,2,3,3,3-heptafluoropropane
22052-86-4
CF3CF2CF2OCH2CH3
61
61
2-Ethoxy-3,3,4,4,5-pentafluorotetrahydro-2,5-bis[1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl]-furan
920979-28-8
C12H5F19O2
56
56
1-Ethoxy-1,1,2,3,3,3-hexafluoropropane
380-34-7
CF3CHFCF2OCH2CH3
23
23
Fluoro(methoxy)methane
460-22-0
CH3OCH2F
13
13
1,1,2,2-Tetrafluoro-3-methoxy-propane; Methyl 2,2,3,3-tetrafluoropropyl ether
60598-17-6
CHF2CF2CH2OCH3
0.5
0.49
1,1,2,2-Tetrafluoro-1-(fluoromethoxy)ethane
37031-31-5
CH2FOCF2CF2H
871
871
Difluoro(fluoromethoxy)methane
461-63-2
CH2FOCHF2
617
617
Fluoro(fluoromethoxy)methane
462-51-1
CH2FOCH2F
130
130
                     Saturated Chlorofluorocarbons (CFCs)
E-R316c
3832-15-3
trans-cyc (-CClFCF2CF2CClF-)
2000*
4,230
Z-R316c
3934-26-7
cis-cyc (-CClFCF2CF2CClF-)
2000*
5,660
                             Fluorinated Formates
Trifluoromethyl formate
85358-65-2
HCOOCF3
588
588
Perfluoroethyl formate
313064-40-3
HCOOCF2CF3
580
580
1,2,2,2-Tetrafluoroethyl formate
481631-19-0
HCOOCHFCF3
470
470
Perfluorobutyl formate
197218-56-7
HCOOCF2CF2CF2CF3
392
392
Perfluoropropyl formate
271257-42-2
HCOOCF2CF2CF3
376
376
1,1,1,3,3,3-Hexafluoropropan-2-yl formate
856766-70-6
HCOOCH(CF3)2
333
333
2,2,2-Trifluoroethyl formate
32042-38-9
HCOOCH2CF3
33
33
3,3,3-Trifluoropropyl formate
1344118-09-7
HCOOCH2CH2CF3
17
17
                             Fluorinated Acetates
Methyl 2,2,2-trifluoroacetate
431-47-0
CF3COOCH3
52
52
1,1-Difluoroethyl 2,2,2-trifluoroacetate
1344118-13-3
CF3COOCF2CH3
31
31
Difluoromethyl 2,2,2-trifluoroacetate
2024-86-4
CF3COOCHF2
27
27
2,2,2-Trifluoroethyl 2,2,2-trifluoroacetate
407-38-5
CF3COOCH2CF3
7
7
Methyl 2,2-difluoroacetate
433-53-4
HCF2COOCH3
3
3
Perfluoroethyl acetate
343269-97-6
CH3COOCF2CF3
2.1
2
Trifluoromethyl acetate
74123-20-9
CH3COOCF3
2.0
2
Perfluoropropyl acetate
1344118-10-0
CH3COOCF2CF2CF3
1.8
2
Perfluorobutyl acetate
209597-28-4
CH3COOCF2CF2CF2CF3
1.6
2
Ethyl 2,2,2-trifluoroacetate
383-63-1
CF3COOCH2CH3
1.3
1
                              Carbonofluoridates
Methyl carbonofluoridate
1538-06-3
FCOOCH3
95
95
1,1-Difluoroethyl carbonofluoridate
1344118-11-1
FCOOCF2CH3
27
27
            Fluorinated Alcohols Other Than Fluorotelomer Alcohols
Bis(trifluoromethyl)-methanol
920-66-1
(CF3)2CHOH
195
182
2,2,3,3,4,4,5,5-Octafluorocyclopentanol
16621-87-7
cyc (-(CF2)4CH(OH)-)
73
13
2,2,3,3,3-Pentafluoropropanol
422-05-9
CF3CF2CH2OH
42
19
2,2,3,3,4,4,4-Heptafluorobutan-1-ol
375-01-9
C3F7CH2OH
25
34
2,2,2-Trifluoroethanol
75-89-8
CF3CH2OH
20
20
2,2,3,4,4,4-Hexafluoro-1-butanol
382-31-0
CF3CHFCF2CH2OH
17
17
2,2,3,3-Tetrafluoro-1-propanol
76-37-9
CHF2CF2CH2OH
13
13
2,2-Difluoroethanol
359-13-7
CHF2CH2OH
3
3
2-Fluoroethanol
371-62-0
CH2FCH2OH
1.1
1.1
4,4,4-Trifluorobutan-1-ol
461-18-7
CF3(CH2)2CH2OH
0.05
0.05
                Non-Cyclic, Unsaturated Perfluorocarbons (PFCs)
PFC-1114; TFE
116-14-3
CF2=CF2; C2F4
0.004
0.004
PFC-1216; Dyneon HFP
116-15-4
C3F6; CF3CF=CF2
0.05
0.05
Perfluorobut-2-ene
360-89-4
CF3CF=CFCF3
1.82
2
Perfluorobut-1-ene
357-26-6
CF3CF2CF=CF2
0.10
0.10
Perfluorobuta-1,3-diene
685-63-2
CF2=CFCF=CF2
0.003
0.003
Non-Cyclic, Unsaturated Hydrofluorocarbons (HFCs) and Hydrochlorofluorocarbons (HCFCs)
HFC-1132a; VF2
75-38-7
C2H2F2, CF2=CH2
0.04
0.04
HFC-1141; VF
75-02-5
C2H3F, CH2=CHF
0.02
0.02
(E)-HFC-1225ye
5595-10-8
CF3CF=CHF(E)
0.06
0.06
(Z)-HFC-1225ye
5528-43-8
CF3CF=CHF(Z)
0.22
0.22
Solstice 1233zd(E)
102687-65-0
C3H2ClF3; CHCl=CHCF3
1.34
1
HCFO-1233zd(Z)
99728-16-2
(Z)-CF3CH=CHCl
1*
0.45
HFC-1234yf; HFO-1234yf
754-12-1
C3H2F4; CF3CF=CH2
0.31
0.31
HFC-1234ze(E)
1645-83-6
C3H2F4; trans-CF3CH=CHF
0.97
0.97
HFC-1234ze(Z)
29118-25-0
C3H2F4; cis-CF3CH=CHF; CF3CH=CHF
0.29
0.29
HFC-1243zf; TFP
677-21-4
C3H3F3, CF3CH=CH2
0.12
0.12
(Z)-HFC-1336
692-49-9
CF3CH=CHCF3(Z)
1.58
2
HFO-1336mzz(E)
66711-86-2
(E)-CF3CH=CHCF3
1*
18
HFC-1345zfc
374-27-6
C2F5CH=CH2
0.09
0.09
HFO-1123
359-11-5
CHF=CF2
1*
0.005
HFO-1438ezy(E)
14149-41-8
(E)-(CF3)2CFCH=CHF
1*
8.2
HFO-1447fz
355-08-8
CF3(CF2)2CH=CH2
1*
0.24
Capstone 42-U
19430-93-4
C6H3F9, CF3(CF2)3CH=CH2
0.16
0.16
Capstone 62-U
25291-17-2
C8H3F13, CF3(CF2)5CH=CH2
0.11
0.11
Capstone 82-U
21652-58-4
C10H3F17, CF3(CF2)7CH=CH2
0.09
0.09
(e)-1-chloro-2-fluoroethene
460-16-2
(E)-CHCl=CHF
1*
0.004
3,3,3-trifluoro-2-(trifluoromethyl)prop-1-ene
382-10-5
(CF3)2C=CH2
1*
0.38
                         Non-Cyclic, Unsaturated CFCs
CFC-1112
598-88-9
CClF=CClF
1*
0.13
CFC-1112a
79-35-6
CCl2=CF2
1*
0.021
                  Non-Cyclic, Unsaturated Halogenated Ethers
PMVE; HFE-216
1187-93-5
CF3OCF=CF2
0.17
0.17
Fluoroxene
406-90-6
CF3CH2OCH=CH2
0.05
0.05
Methyl-perfluoroheptene-ethers
N/A
CH3OC7F13
1*
15
                  Non-Cyclic, Unsaturated Halogenated Esters
Ethenyl 2,2,2-trifluoroacetate
433-28-3
CF3COOCH=CH2
1*
0.008
Prop-2-enyl 2,2,2-trifluoroacetate
383-67-5
CF3COOCH2CH=CH2
1*
0.007
                       Cyclic, Unsaturated HFCs and PFCs
PFC C-1418
559-40-0
c-C5F8
1.97
2
Hexafluorocyclobutene
697-11-0
cyc (-CF=CFCF2CF2-)
1*
126
1,3,3,4,4,5,5-heptafluorocyclopentene
1892-03-1
cyc (-CF2CF2CF2CF=CH-)
1*
45
1,3,3,4,4-pentafluorocyclobutene
374-31-2
cyc (-CH=CFCF2CF2-)
1*
92
3,3,4,4-tetrafluorocyclobutene
2714-38-7
cyc (-CH=CHCF2CF2-)
1*
26
                             Fluorinated Aldehydes
3,3,3-Trifluoro-propanal
460-40-2
CF3CH2CHO
0.01
0.01
                              Fluorinated Ketones
Novec 1230 (perfluoro (2-methyl-3-pentanone))
756-13-8
CF3CF2C(O)CF(CF3)2
0.1
0.11
1,1,1-trifluoropropan-2-one
421-50-1
CF3COCH3
1*
0.09
1,1,1-trifluorobutan-2-one
381-88-4
CF3COCH2CH3
1*
0.095
                            Fluorotelomer Alcohols
3,3,4,4,5,5,6,6,7,7,7-Undecafluoroheptan-1-ol
185689-57-0
CF3(CF2)4CH2CH2OH
0.43
0.43
3,3,3-Trifluoropropan-1-ol
2240-88-2
CF3CH2CH2OH
0.35
0.35
3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-Pentadecafluorononan-1-ol
755-02-2
CF3(CF2)6CH2CH2OH
0.33
0.33
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-Nonadecafluoroundecan-1-ol
87017-97-8
CF3(CF2)8CH2CH2OH
0.19
0.19
                  Fluorinated GHGs With Carbon-Iodine Bond(s)
Trifluoroiodomethane
2314-97-8
CF3I
0.4
0.4
            Remaining Fluorinated GHGs with Chemical-Specific GWPs
Dibromodifluoromethane (Halon 1202)
75-61-6
CBr2F2
231
231
2-Bromo-2-chloro-1,1,1-trifluoroethane (Halon-2311/Halothane)
151-67-7
CHBrClCF3
41
41
Heptafluoroisobutyronitrile
42532-60-5
(CF3)2CFCN
2000*
2,750
Carbonyl fluoride
353-50-4
COF2
2000*
0.14**
*Table A-1 does not include a chemical-specific value for this GHG; the value shown is the current default GWP for the fluorinated GHG group of which the GHG is currently a member.
**Proposed in 2022 Data Quality Improvements Proposal.
 Appendix B: Proposed Fluorinated GHG Groups and Default GWPs
                             Fluorinated GHG Group
                  Current Global Warming Potential (100 Yr.)
                  Proposed Global Warming Potential (100 Yr.)
Fully fluorinated GHGs
10,000
9,200
Saturated hydrofluorocarbons (HFCs) with two or fewer carbon-hydrogen bonds
3,700
3,000
Saturated HFCs with three or more carbon-hydrogen bonds
930
840
Saturated hydrofluoroethers (HFEs) and hydrochlorofluoroethers (HCFEs) with one carbon-hydrogen bond
5,700
6,600
Saturated HFEs and HCFEs with two carbon-hydrogen bonds
2,600
2,900
Saturated HFEs and HCFEs with three or more carbon-hydrogen bonds
270
320
Saturated chlorofluorocarbons (CFCs)
2,000*
4,900
Fluorinated formates
350
350
Cyclic forms of the following: unsaturated perfluorocarbons (PFCs), unsaturated HFCs, unsaturated CFCs, unsaturated hydrochlorofluorocarbons (HCFCs), unsaturated bromofluorocarbons (BFCs), unsaturated bromochlorofluorocarbons (BCFCs), unsaturated hydrobromofluorocarbons (HBFCs), unsaturated hydrobromochlorofluorocarbons (HBCFCs), unsaturated halogenated ethers, and unsaturated halogenated esters
1**
58
Fluorinated acetates, carbonofluoridates, and fluorinated alcohols other than fluorotelomer alcohols
30
25
Fluorinated aldehydes, fluorinated ketones, and non-cyclic forms of the following: unsaturated PFCs, unsaturated HFCs, unsaturated CFCs, unsaturated HCFCs, unsaturated BFCs, unsaturated BCFCs, unsaturated HBFCs, unsaturated HBCFCs, unsaturated halogenated ethers, and unsaturated halogenated esters
1
1
Fluorotelomer alcohols
1
1
Fluorinated GHGs with carbon-iodine bond(s)
1
1
Remaining fluorinated GHGs
2,000
1,800
*Based on current classification as "Other fluorinated GHGs"
**Based on current classification as "Unsaturated perfluorocarbons (PFCs), unsaturated HFCs, unsaturated hydrochlorofluorocarbons (HCFCs), unsaturated halogenated ethers, unsaturated halogenated esters"