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.
<IP_ADDRESS>.	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

<IP_ADDRESS> 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.