Appendix E Calculation Methods Appendix

Appendix E
Calculation Methods Appendix $-$ Part II.C.1 and II.C.2

II.C. Energy-Related Emissions

This section provides more detail on how the Commission calculated scope 1 unit process emissions from fuel combustion $(S 1 F C U G H G_{p r o d u c t}$ ) and scope 2 unit process emissions from purchased energy $(S 2 U G H G_{p r o d u c t}$ ). The Commission’s energy-related calculations incorporate facility-wide data and produce partial scope 1 and complete scope 2 emissions subprocess-specific estimates, further mapped to reference products’ unit processes.514F[511] The scope 1 fuel combustion emissions described in this section are combined with the scope 1 process emissions to calculate total scope 1 estimates for each product category.

II.C.1. Data Collected in the Questionnaire

As noted in chapter 3 (“Energy Emissions (Scopes 1 and 2)”), the Commission used a combination of data collected from section 3 (fuel combustion) and section 4 (purchased energy) of its questionnaire and public EPA data to calculate energy-related emissions. The types of data collected, where they were requested in the questionnaire, and whether they were used for scope 1 calculations, scope 2 calculations, or both are summarized in table E.7.

Table E.7 Use of questionnaire data for scope 1 fuel combustion and scope 2 emissions calculations

Data collected	Questionnaire questions	Used for scope 1 fuel combustion emissions	Used for scope 2 emissions
Fuel types and quantities combusted	3.5, 3.6	Yes	No
Quantity and sourcing of purchased electricity	4.1, 4.2a, 4.4b, 4.5a	No	Yes
Quantity and sourcing of heat, steam, and hot water from third-party operated units	3.2c $-$ e, 3.3b, 4.7	No	Yes
On-site generation of electricity, heat, steam, and hot water by the facility operator; use of fuels in these operations	3.2c $-$ e, 3.3c, 3.4c $-$ e; 3.7	Yes	No
Subprocess-specific use of fuels, electricity, steam, heat, and hot water	3.8 $-$ 3.12	Yes	Yes

Source: Compiled by the USITC; USITC, Greenhouse Gas (GHG) Emissions Intensities Questionnaire: Facility-Level, 2024, responses to questions 3.1 $-$ 4.7.

Note: Qualitative responses to additional questionnaire questions (such as 3.13 and 4.4e) were also used to inform data cleaning and the emissions calculations. The questionnaire sources list does not include filter questions. The Commission did not receive any relevant responses to questionnaire questions 4.4f or 4.5b.

For the main results presented in chapters 4 and 5, data from questions 4.4b and 4.5a were only used when the electricity was reported as supplied via a direct-line connection. The calculations used the 4.4b and 4.5a data, as well as data from questions 3.4b, 4.3c, and 4.3d for the market-based method sensitivity analysis presented in appendix F (“Market-Based Method”).

The requests from the USTR letter to use available facility-level data and to measure product-specific emissions across the entire U.S. industry required development of a method to disaggregate the facility-level emissions data to product-specific data. For facilities that only produced one category of products or that already had energy meters on different production lines, these data were typically directly measured and could be pulled from company records.515F[512] However, for many other facilities, any product-specific allocations of energy use needed to be estimated.516F[513] During questionnaire development, industry representatives suggested that the methodology for estimating these allocations was best left to each facility respondent, rather than adopting a single methodology and applying it to a range of facilities making different products and using different manufacturing processes and equipment.517F[514] To make these allocations less burdensome for questionnaire respondents, the Commission designed the questionnaire to collect energy use allocations for a short list of subprocesses rather than each product category. As discussed further in “Computing Product-Level Emissions Inventories,” when facilities used the same production subprocess to make multiple covered products, the Commission divided the subprocess-specific emissions proportionally among the product categories based on the relative tonnage of production.

The Commission’s questionnaire asked respondents to estimate allocations of the amounts of fuel combustion (by each fuel type; question 3.8); electricity (question 3.9); and useful thermal outputs of steam, heat, and hot water (questions 3.10 $-$ 3.12) used in different subprocesses. These subprocesses fell into one of four categories, listed below. Table E.8 then presents the categorization for each subprocess.

· Subprocesses associated with upstream material inputs for covered steel and aluminum production

· Subprocesses associated with different types of covered steel and aluminum production

· Subprocesses associated with building-wide energy use that may support multiple categories of production (including noncovered production)

· Subprocesses associated with noncovered production, activities unrelated to the facility’s production of covered steel or aluminum, or activities that are otherwise outside of the Commission’s system boundaries for covered steel and aluminum production

Categories A and B are both in-scope subprocesses whose emissions are ultimately allocated to this report’s product-specific emissions for covered steel and aluminum. Category C only applies to one subprocess (energy use for ambient heating, cooling, ventilation, and lighting supply), whose emissions are redistributed among other subprocesses as the last step to arrive at unit process emissions for scope 1 fuel combustion and scope 2 energy emissions. Category D subprocesses are treated as out of scope; the energy use and the resulting emissions associated with these subprocesses are not included in the product-specific emissions estimates in this report.

Table E.8 Subprocesses used for energy allocations (as presented in questions 3.8 $-$ 3.12) and their categorization and industry

Category A is for in-scope production of material inputs, Category B is for in-scope production of covered products, Category C is for a facility-wide subprocess that is reallocated among the facility’s production subprocesses (both in scope and out of scope), and Category D is for out-of-scope subprocesses. BOF = blast oxygen furnace; EAF = electric arc furnace.

Subprocess	Category	Industry
Stationary equipment that shreds or sorts scrap	D	Aluminum and Steel
Anode baking for primary unwrought aluminum production	A	Aluminum
Smelting of primary unwrought aluminum	B	Aluminum
Casting of primary unwrought aluminum	B	Aluminum
Secondary unwrought aluminum production	B	Aluminum
Wrought aluminum production	B	Aluminum
Metallurgical coke production	A	Steel
Lime and dolime production	A	Steel
Iron sinter production	A	Steel
Production of oxygen, nitrogen, argon, or hydrogen	A	Steel
Liquid pig iron production in a rotary hearth furnace	A	Steel
Blast furnace operations, including pig iron casting	A	Steel
Steelmaking, including BOF or EAF operations, preheating ferrous scrap, refining/ladle station, decarburization, and casting	B	Steel
Remelting and further working of previously cast semifinished steel into different forms of semifinished steel	B	Steel
Hot-rolling flat steel products	B	Steel
Cold-rolling flat steel products	B	Steel
Coating, cladding, or plating flat steel products	B	Steel
Production of seamless tubular products	B	Steel
Production of non-seamless tubular products	B	Steel
Hot-working long steel products	B	Steel
Cold-forming or cold-finishing long steel products	B	Steel
Processes used to make products other than covered steel, covered aluminum, or their upstream material inputs	D	Aluminum and Steel
Activities of other producers operating on-site	D	Aluminum and Steel
Ambient heating, cooling, ventilation, and lighting supply in facilities where production occurs, if measured separately from the process-specific fuel use reported above	C	Aluminum and Steel
Ancillary (non-production) activities that are not associated with production floor operations	D	Aluminum and Steel

Source: Subprocesses listed in USITC, Greenhouse Gas (GHG) Emissions Intensities Questionnaire: Facility-Level, 2024, section 3.

The energy calculations deliberately start with facility-wide emissions estimates derived from measured data points such as facility-wide natural gas combustion and total purchased electricity (both metered data points that can be obtained from billing records). This limits reliance on the less precise subprocess-specific estimates to calculations for facilities that use multiple types of production subprocesses (e.g., hot-rolling flat steel and cold-rolling flat steel) or have both in-scope and out-of-scope activities (e.g., have in-scope production and on-site wastewater treatment). The Commission conducted extensive checks for outliers, outreach to questionnaire respondents, and data cleaning to improve the accuracy of these allocations.

II.C.2. Energy Calculations for Facilities with Less Complicated Energy Sourcing

The Commission’s calculations were designed to cover all types of energy sourcing situations, including situations that applied only to one facility or a handful of facilities in the survey population. Rather than present this full set of calculations at once, this section starts with an explanation of how the energy calculations worked for most facilities producing covered steel and aluminum products in 2022 (i.e., those without the uncommon sourcing situations). However, this set of calculations does not fully cover the calculations applied to some of the largest U.S. steel and aluminum producers. These more complicated calculations $—$ applied to facilities that reported fuel combustion emissions from a continuous emissions monitoring system (CEMS); generated electricity on-site; or generated or purchased steam, heat, or hot water for their production operations $—$ are covered later in the section.

The energy calculations start by measuring scope 1 fuel combustion emissions. First, the calculations estimate the facility’s total GHG emissions from fuel combustion for each fuel type combusted. For most facilities, this only consists of natural gas emissions. Second, the calculations use questionnaire data on how much fuel was used in each subprocess to estimate subprocess-specific shares of fuel use, for each fuel type combusted. The fuel combustion emissions are then multiplied by the subprocess-specific shares to calculate subprocess-specific fuel combustion emissions. When multiple fuel types are used, the calculations sum all fuel combustion emissions for each subprocess.

Next, the calculations pivot to scope 2 emissions. As with the scope 1 fuel combustion emissions, the scope 2 part of the energy calculations first estimates a facility-wide total. For the simple version of the scope 2 emission calculations, the calculations multiply total purchased electricity reported in the questionnaire by the emissions factor for the facility’s eGRID subregion (as discussed in chapter 3, “Scope 2 Emissions”). The calculations then use questionnaire data on how much electricity was used in each subprocess to estimate subprocess-specific shares of electricity use. After that, the calculations multiply the subprocess-specific shares by the facility-wide emissions from purchased electricity to obtain subprocess-specific scope 2 emissions estimates.

Finally, the calculations reallocate subprocess-specific fuel combustion and electricity estimates from the questionnaire for “ambient heating, cooling, ventilation, and lighting supply in facilities where production occurs, if measured separately from the other fuel use” among in-scope production subprocesses and out-of-scope production, using the physical allocation approach.518F[515] For example, a facility reporting 10 mt of production of aluminum castings and 20 mt of bronze castings would have one-third of its scope 1 fuel combustion emissions for ambient energy use added to its scope 1 fuel combustion emissions for the unit process “wrought aluminum production.”519F[516]

II.C.2.a Calculating Facility-Wide Scope 1 Fuel Combustion Emissions

As a first step, the energy calculations total estimates for facility-wide fuel combustion, separated by fuel type. When facilities reported no on-site fuel combustion (questionnaire question 3.5), the calculations set scope 1 fuel combustion emissions to zero. For facilities that reported on-site fuel combustion, the calculation step follows two different paths, depending on whether the facility reported 2022 data to the EPA’s GHGRP.

When a facility reported 2022 data to the GHGRP, the calculations use the public GHGRP ID to match the facility to its EPA data.520F[517] As noted in chapter 3 (“Scope 1 Fuel Combustion Emissions”), most of the GHGRP data in subpart C is available as fuel-specific and unit-specific values for CO₂, methane, and nitrous oxide (with the latter two gases measured in CO₂e). The calculations aggregate these values to fuel-specific, facility-wide GHG emission totals. For facilities producing covered steel products, GHGRP reporters comprised about 98 percent of total facility-wide fuel combustion emissions. For facilities producing covered aluminum products, GHGRP reporters comprised about 82 percent of total facility-wide fuel combustion emissions.521F[518]

When facility-specific 2022 GHGRP data are not available, the calculations instead apply fuel-specific direct emissions factors used by the GHGRP to the fuel type and quantity data reported in the questionnaire.522F[519] The calculations combine several different GHGRP factors for these estimates: gross heat content to convert fuel quantities from volume or mass to thermal energy; CO₂, methane, and nitrous oxide emissions factors to estimate the direct emissions from fuel combustion; and global warming potentials to convert the methane and nitrous oxide emissions to CO₂e emissions.523F[520]

The first GHGRP factor used is the gross heat content for each fuel type (also referred to as high heating value or higher heating value), measured in million British thermal units (MMBtu) per unit of volume or weight. This is an estimate based on the average U.S. heat content of a given fuel type, so it is not as precise as conversions between units that are measuring the same thing (e.g., converting liters to gallons or short tons to kilograms). Because natural gas is sometimes billed and metered based on its heat content, the questionnaire allowed respondents to directly report natural gas quantities in MMBtu or therms (a different measure of heat content equivalent to approximately 0.1 MMBtu). More than half of the non-GHGRP reporting facilities reporting natural gas use reported natural gas in thermal energy units (MMBtu or therms). The calculations only applied the GHGRP’s average gross heat content for U.S. natural gas to the non-GHGRP-reporting facilities that reported natural gas in standard cubic feet. The calculations also applied fuel-specific average heat content values to the 11 other fuel types that non-GHGRP facilities reported in their questionnaire responses, but these were a small minority of the fuel combustion emissions. Fewer than 50 non-GHGRP-reporting facilities reported combusting liquefied propane, and the 10 other fuel types (diesel, heavy gas oil, kerosene, liquefied petroleum gas, motor gasoline, propane gas, propylene, residual fuel oil, used oil, and other oil) were each rarely reported by non-GHGRP-reporting facilities.524F[521]

Second, the Commission constructed a fuel-specific GHG emissions factor, using the GHGRP’s direct emissions factors (converted from kilograms to metric tons; $C O_{2} E F_{f u e l}$ , $C H_{4} E F_{f u e l}$ , and $N_{2} O E F_{f u e l}$ ) and the global warming potentials for CO₂, methane, and nitrous oxide emissions.525F[522] For each fuel type, $C O_{2} E F_{f u e l}$ determines nearly all of the constructed GHG emissions factors. The methane and nitrous oxide emissions factors were significantly smaller and were not as differentiated. The only distinction provided in the GHGRP’s emissions factors for these GHGs is between the emissions factors for natural gas and the emissions factors to apply to all petroleum products (covering the 11 other fuel types mentioned above). Before adding the methane and nitrous oxide emissions factors to the CO₂ emissions factor, the calculations convert the emissions factors to a CO₂e measure. This last conversion uses the global warming potential factors in GHGRP table A-1, which notes that methaneemissions are 25 times as potent ( $C H_{4} G W P$ ) and nitrous oxide emissions are 298 times as potent ( $N_{2} O G W P$ ) as a metric ton of CO₂ emissions, respectively, based on a 100-year time horizon.526F[523]

Third, equation E.6 multiplied the fuel quantity in MMBtu ( $u s e_{f u e l}$ ) reported in question 3.6 by the fuel-specific CO₂e emissions factor. The resulting estimates are facility-wide GHG emissions from each fuel type combusted ( $f a c i l i t y G H G_{f u e l}$ ), effectively applying a GHGRP Tier 1 approach to the questionnaire data. These non-GHGRP reporter facility-wide fuel combustion emissions then follow the same energy calculation steps as the fuel combustion emissions for GHGRP-reporting facilities.

$\begin{matrix} f a c i l i t y G H G_{f u e l} = u s e_{f u e l} * [C O_{2} E F_{f u e l} + (C H_{4} E F_{f u e l} * C H_{4} G W P) \\ + (N_{2} O E F_{f u e l} * N_{2} O G W P)] (E .6) \end{matrix}$

Box E.2 Effects of Using Alternate Global Warming Potentials

This report uses a consistent set of global warming potential (GWP) factors from the U.S. Environmental Protection Agency’s Greenhouse Gas Reporting Program (GHGRP) to convert emissions from methane (CH₄), nitrous oxide (N₂O), and perfluorocarbons (C₂F₆ and CF₄) into a single carbon dioxide equivalent value. These GHGRP factors match the factors published by The United Nations’ Intergovernmental Panel on Climate Change (IPCC) in its 4th Assessment Report.a Box table 1 presents GHG-specific data aggregated across all facilities that responded to the Commission’s questionnaire and reported to the GHGRP in 2022, before the GWP factors were applied.

Box Table 1: Total emissions from the GHGRP for facilities producing covered steel products and facilities producing covered aluminum products

In metric tons (mt), $—$ (em dash)= not applicable.

Facility type	CO₂	CH₄	N₂O	C₂F₆	CF₄
Steel facilities	49,380,294	288.8	41.5	$—$	$—$
Aluminum facilities	9,311,517	647.3	91.8	7.5	93.8

Source: EPA, OAP, GHGRP, 2022 Data Summary Spreadsheets, accessed October 2, 2024.

Note: Data in this table exclude GHGRP emissions from subpart TT (industrial waste landfills), which were outside of this report’s system boundaries for steel and aluminum production. Otherwise, the data directly reflect a total of the GHGRP’s emissions data across all facilities that reported to the GHGRP in 2022 and responded to the Commission’s questionnaire for this investigation.

Box table 2 below presents a summary of these emissions data from steel and aluminum facilities after the data were converted to metric tons of carbon dioxide equivalent (mt CO₂e) using the GWP factors from the GHGRP, which are the factors used in the analysis in the main text of this report. For steel facilities, over 99.9 percent of the GHG emissions (in mt CO₂e) sourced from the GHGRP data came from CO₂. For aluminum facilities, about 91.8 percent of the GHG emissions sourced from the GHGRP data came from CO₂ and another 7.7 percent came from C₂F₆ and CF₄ at primary aluminum smelters.

Box Table 2: Total emissions from the GHGRP for facilities producing covered steel products and facilities producing covered aluminum products

In metric tons of carbon dioxide equivalent (mt CO₂e), and percentages (%); $—$ (em dash)= not applicable.

GHG	GHGRP GWPs used in the report	Steel facility emissions (mt CO₂e)	GHG share of steel facility emissions (%)	Aluminum facility emissions (mt CO₂e)	GHG share of aluminum facility emissions (%)
CO₂	1	49,380,294	99.96	9,311,517	91.8
CH₄	25	7,221	0.01	16,183	0.2
N₂O	298	12,360	0.03	27,344	0.3
C₂F₆	12,200	$—$	$—$ .	91,250	0.9
CF₄	7,390	$—$	$—$	693,221	6.8
Total	$—$	49,399,875	100.0	10,139,515	100.0

Sources: EPA, OAP, GHGRP, 2022 Data Summary Spreadsheets, accessed October 2, 2024; 40 C.F.R., table A-1 to subpart A of part 98.

Note: Data in this table exclude GHGRP emissions from subpart TT (industrial waste landfills), which were outside of this report’s system boundaries for steel and aluminum production. Otherwise, the data directly reflect the GHGRP’s facility-wide totals across all facilities that reported to the GHGRP in 2022 and responded to the Commission’s questionnaire for this investigation.

However, there is not a single, authoritative set of GWP factors to use. The United Nations’ Intergovernmental Panel on Climate Change (IPCC) releases updated GWP factors in each of its Assessment Reports, adjusted to reflect more recent research on the impacts of these gases.b The IPCC’s Assessment Reports also do not always provide a single GWP for each gas. For example, the 5th Assessment Report provides different GWP factors to use for CH₄ depending on the time horizon (20-year versus 100-year), whether the CH₄ comes from fossil fuel or biogenic sources, and whether certain indirect effects (referred to as climate-carbon feedbacks) are included. For the 20-year time horizon, these GWPs for CH₄ range from 84 to 87; for the 100-year time horizon, they range from 28 to 36.c

Because CO₂ comprises the vast majority of GHGs associated with these facilities in tonnage terms, applying a much higher GWP for CH₄ to the data above does not substantially affect the overall total of these emissions in carbon dioxide equivalent terms. For example, if a 20-year time-horizon GWP of 87 were used, CH₄ emissions across all GHGRP-reporting facilities that produced covered steel products would only increase by 17,907 mt CO₂e (less than 0.1 percent of the total GHG emissions).d For GHGRP-reporting facilities that produced covered aluminum products, CH₄ emissions would increase by 40,134 mt CO₂e (about 0.4 percent of the total GHG emissions).e For facilities that did not report to the GHGRP, natural gas was responsible for almost all the scope 1 fuel combustion emissions; applying the higher CH₄GWP factor would have increased those natural gas combustion emissions by about 0.1 percent.f

a 40 C.F.R., table A-1 to subpart A of part 98 (2024); Solomon et al., Technical Summary of AR4, 2007, 33.

b One example of this is that the measurement of climate-carbon feedback in the CH₄ factors changed between two of the IPCC reports. Myhre et al., “Anthropogenic and Natural Radiative Forcing,” 2013, 713 $-$ 14; Forster et al., “The Earth’s Energy Budget, Climate Feedbacks and Climate Sensitivity,” 2021, 1013 and 1017.

c The IPCC released updated GWPs in 2021 in its 6th Assessment Report, but the 5^th Assessment Report’s 100-year time-horizon GWPs are being used by parties to the Paris Agreement (providing comparability with national inventory data from earlier years). UNFCCC, “National Inventory Reports,” accessed October 15, 2024; UNFCCC, Report of the COP24, May 14, 2019, 25; Myhre et al., “Anthropogenic and Natural Radiative Forcing,” 2013, 713 and 741; Forster et al., “The Earth’s Energy Budget, Climate Feedbacks and Climate Sensitivity,” 2021, 117.

d Total GHG emissions for these comparisons only apply a 20-year GWP to CH₄ and use the 100-year GHGRP GWPs for all other gases. While CH₄ has a lifetime of less than 20 years, N₂O, C₂F₆, and CF₄ all have lifetimes over 100 years. Therefore the 20-year GWPs for these other GHGs are lower than the 100-year GWPs. Solomon et al., Technical Summary of AR4, 2007, 33.

e Over 90 percent of the CH₄ emissions in the GHGRP data from aluminum facilities come from a single aluminum smelter’s coal use. The coal is used in a utility-scale, coal-fired power plant that sells some excess electricity back to the grid, so these emissions overstate how much CH4 is allocated to U.S. aluminum production. EPA, OAP, GHGRP, 2022 Data Summary Spreadsheets, accessed October 2, 2024; EPA, OAP, GHGRP, FLIGHT database, “2022 Greenhouse Gas Emissions from Large Facilities,” accessed October 2, 2024; FERC, “Order Granting in Part and Denying in Part Requests for Waiver, Docket No. ER20-1580-000,” July 16, 2020, 3 $-$ 4.

f Each MMBtu of natural gas combusted at a facility that did not report to the GHGRP was assumed to result in 5.306 x 10-2 mt CO₂, 10-6 mt CH₄, and 10-7 mt N₂O. When taken together, the GHGRP’s Tier 1 default emissions factors and GWP factors that were used for non-GHGRP facilities assume that CO₂ is responsible for 99.9 percent of the GHG emissions from combusting natural gas. USITC estimates based on its calculation methodology; 40 C.F.R., tables C-1 and C-2 to subpart C of part 98.

II.C.2.b Allocating Fuel Combustion Emissions to Subprocesses

For facilities with simple energy sourcing, facility-wide scope 1 fuel combustion emissions are allocated to subprocesses in two steps (equations E.7 and E.8). After estimating the facility-wide emissions from each type of fuel combusted ( $f a c i l i t y G H G_{f u e l}$ ), the calculations use proportional shares of fuel use by subprocess from questionnaire question 3.8 ( $Σ_{s u b p r o c} (u s e_{f u e l, s u b p r o c})$ ) to develop fuel-specific estimates for subprocess-specific fuel combustion emissions $(S 1 F C_{f u e l, s u b p r o c}$ ) (equation E.7). Second, for each subprocess, the emissions are totaled across all fuel types ( $Σ_{f u e l} (S 1 F C_{f u e l, s u b p r o c}))$ , resulting in subprocess-specific emissions ( $S 1 F C_{s u b p r o c}$ ) (equation E.8).

$\begin{matrix} S 1 F C_{f u e l, s u b p r o c} = f a c i l i t y G H G_{f u e l} * \frac{u s e_{f u e l, s u b p r o c}}{Σ_{s u b p r o c} (u s e_{f u e l, s u b p r o c})} (E .7) \end{matrix}$

$\begin{matrix} S 1 F C_{s u b p r o c} = Σ_{f u e l} (S 1 F C_{f u e l, s u b p r o c}) (E .8) \end{matrix}$

II.C.2.c Calculating Facility-Wide Scope 2 Emissions

For facilities with simple energy sourcing, equation E.9 estimates scope 2 emissions by multiplying the total quantity of electricity purchased from question 4.1 ( $p u r c h_{e l e c}$ ) by the confirmed eGRID subregion for the facility from question 4.2a $(e G R I D_{s r l}$ ).527F[524]

$\begin{matrix} f a c i l i t y G H G S 2 = p u r c h_{e l e c} * e G R I D_{s r l} * \frac{1}{2, 204.62} (E .9) \end{matrix}$

II.C.2.d Allocating Scope 2 Emissions to Subprocesses

As with fuel combustion emissions, equation E.10 uses proportional shares of energy use $—$ this time from questionnaire question 3.10 $—$ to develop subprocess-specific estimates for scope 2 ( $S 2_{s u b p r o c}$ ).

$\begin{matrix} S 2_{s u b p r o c} = f a c i l i t y G H G S 2 * \frac{u s e_{e l e c, s u b p r o c}}{Σ_{s u b p r o c} (u s e_{e l e c, s u b p r o c})} (E .10) \end{matrix}$

II.C.2.e Reallocating Emissions from Ambient Heating, Cooling, Ventilation, and Lighting Supply

As noted above, the Commission used a physical allocation to allocate any emissions from a subprocess that corresponds to multiple reference products (e.g., allocating scope 1 fuel combustion emissions from subprocess “wrought aluminum production” to reference products forgings and castings based on facility production tonnage). The approach to allocate scope 1 fuel combustion and scope 2 energy emissions from ambient heating varies slightly to ensure emissions are allocated to any out-of-scope production by dividing by a facility’s total production ( $o u t p u t)$ (equation E.10).

$\begin{matrix} S 1 F C_{a m b i e n t, p r o d u c t} = (S 1 F C_{a m b i e n t} * \frac{o u t p u t_{p r o d u c t}}{o u t p u t}) (E .11) \end{matrix}$

II.C.2.f Unit Process Emissions from Scope 1 Fuel Combustion and Scope 2 Energy

To transform scope 1 fuel combustion and scope 2 energy emissions from all other subprocesses to the unit process level unique to each reference product, equations E.12.a and E.12.b multiply subprocess-specific emissions by the reference product’s share of total output corresponding to the subprocess.

$S 1 F C_{s u b p r o c, p r o d u c t} = S 1 F C_{s u b p r o c} * \frac{o u t p u t_{p r o d u c t}}{o u t p u t_{s u b p r o c}} (E .12. a)$

$S 2_{s u b p r o c, p r o d u c t} = S 2_{s u b p r o c} * \frac{o u t p u t_{p r o d u c t}}{o u t p u t_{s u b p r o c}} (E .12. b)$

Then, equations E.13.a and E.13.b add the emissions associated with energy use for ambient heating, cooling, ventilation, and lighting supply ( $S 1 F C_{a m b i e n t, p r o d u c t}$ , $S 2_{a m b i e n t, p r o d u c t}$ ) to emissions from other subprocesses associated with on-site production activities for each reference product to arrive at scope 1 fuel combustion and scope 2 unit process emissions for the product-level inventories.528F[525]

$\begin{matrix} S 1 F C U G H G_{p r o d u c t} = \sum_{s u b p r o c} S 1 F C_{s u b p r o c, p r o d u c t} (E .13. a) \end{matrix}$

$\begin{matrix} S 2 U G H G_{p r o d u c t} = \sum_{s u b p r o c} S 2_{s u b p r o c, p r o d u c t} (E .13. b) \end{matrix}$

[511] See “I. Overview of Product-Level Emissions Intensity and Inventory Calculations.”

[512] U.S. industry representative, interview by USITC staff, August 1, 2023.

[513] USITC, Greenhouse Gas (GHG) Emissions Intensities Questionnaire: Facility-Level, 2024, responses to question 3.13; USITC, hearing transcript, December 7, 2023, 77 $-$ 78 (testimony of Joe Green, SSINA).

[514] USITC, hearing transcript, December 7, 2023, 146 (testimony of Jeff Hansen, SDI); 147-148 (testimony of John Hill, Cleveland-Cliffs); 149 $-$ 150 (testimony of Kevin Dempsey, AISI); 150-151 (testimony of Roger Schagrin, Schagrin Associates).

[515] USITC, Greenhouse Gas (GHG) Emissions Intensity Questionnaire: Facility-Level, 2024, section 3.

[516] Questionnaire respondents were provided the option of allocating their energy used for the general building temperature control, ventilation, and lighting directly to production subprocesses rather than reporting it separately. This flexibility was provided in recognition that a facility’s data on its energy use for specific subprocesses can vary considerably, may be measured directly for all subprocesses or for just some subprocesses, or may need to be estimated for anything below a facility-wide measure. Allocating ambient energy use based on relative tonnage may not always accurately capture the product category’s relative use of building space and impact on heating, cooling, lighting, and ventilation demand. However, it allows for an approximate allocation across all relevant production categories while relying on questionnaire data that was also used for other purposes (minimizing respondent burden).

[517] EPA, “GHGRP, Envirofacts GHG Query Builder,” accessed September 18, 2024.

[518] USITC estimates based on its calculation methodology. See appendix F (“Greenhouse Gas Reporting Program Reporters Only”) for more analysis on how data for facilities reporting to the GHGRP compared to data for the Commission’s full survey population.

[519] See table G.1 in appendix G for the fuel combustion emissions factors used for non-GHGRP reporters.

[520] Table A-1 to Subpart A and Tables C-1 and C-2 to Subpart C of Part 98, Title 40.

[521] For non-GHGRP facilities producing covered steel products and for non-GHGRP facilities producing covered aluminum products, nearly all of the emissions associated with facility-wide fuel combustion came from natural gas. USITC estimates based on its calculation methodology.

[522] Table A-1 to Subpart A and Tables C-1 and C-2 to Subpart C of Part 98, Title 40.

[523] See chapter 1 (“Introduction to GHG Emissions”) for more information on global warming potentials and time horizons. Table A-1 to Subpart A of Part 98, Title 40.

[524] The calculations match the facility’s subregion to the 2022 default emissions factor for the subregion provided in eGRID, which is converted from pounds of CO₂e per megawatt-hour (MWh) to metric tons of CO₂e per MWh. The calculations use variable SRC2ERTA for the emissions factor, described as “eGRID subregion annual CO₂ equivalent total output emission rate (lb/MWh).” EPA, “SRL22,” January 30, 2024.

[525] Table E.1 in the “I. Overview of Product-Level Emissions Intensity and Inventory Calculations” section in this appendix details the mapping of subprocesses to their corresponding reference products.