Technical Support Document 

for Greenhouse Gas Emissions Thresholds 

Evaluation

Air Quality Policy Division

Office of Air Quality Policy and Standards

U.S. Environmental Protection Agency

March 29, 2010
i

Table of Contents

Page

1. Purpose...................................................................................................................................... 1

2. Overview ................................................................................................................................... 1

3. Emissions-based Threshold Analysis..................................................................................... 2

3.1 General Description of Overall Approach ........................................................................... 2

3.1.1 Threshold Levels........................................................................................................... 2

3.1.2 Greenhouse Gases......................................................................................................... 3

3.1.3 Source Sectors............................................................................................................... 4

3.1.4 Potential to Emit Methodology..................................................................................... 5

3.1.5 New and Modified Sources........................................................................................... 6

3.2 Threshold Summary Results................................................................................................ 6

3.3 Electricity Generating Sector............................................................................................... 9

3.4 Industrial Sector................................................................................................................. 11

3.4.1 Data Sources............................................................................................................... 14

3.4.2 Potential to Emit ......................................................................................................... 14

3.4.3 Methodology for New Units....................................................................................... 14

3.5 Methodology for Existing Unspecified Industrial Stationary Combustion Source 

Category Emissions............................................................................................................ 15

3.6 Methodology for Existing Specific Industrial Sectors Considering Combustion, 

Process, and Fugitive Emissions........................................................................................ 17

3.6.1 Adipic Acid Production .............................................................................................. 17

3.6.2 Aluminum Production................................................................................................. 19

3.6.3 Ammonia Production.................................................................................................. 21

3.6.4 Cement Production ..................................................................................................... 22

3.6.5 Electronic Production ................................................................................................. 24

3.6.6 Ethanol Production ..................................................................................................... 25

3.6.7 Ferroalloy Production ................................................................................................. 27

3.6.8 Food Processing.......................................................................................................... 29

3.6.9 Glass Manufacturing................................................................................................... 30

3.6.10 HCFC-22 Production ................................................................................................ 31

3.6.11 Hydrogen Production................................................................................................ 33
ii

Table of Contents (cont.)

Page

3.6.12 Iron and Steel Production ......................................................................................... 34

3.6.13 Lead Production........................................................................................................ 37

3.6.14 Lime .......................................................................................................................... 38

3.6.15 Magnesium Production and Processing.................................................................... 39

3.6.16 Nitric Acid Production.............................................................................................. 41

3.6.17 Petrochemical Production......................................................................................... 42

3.6.18 Petroleum Refineries................................................................................................. 44

3.6.19 Phosphoric Acid Production ..................................................................................... 46

3.6.20 Pulp and Paper Manufacturing ................................................................................. 47

3.6.21 Silicon Carbide Manufacturing................................................................................. 48

3.6.22 Soda Ash Production ................................................................................................ 50

3.6.23 Titanium Dioxide Production ................................................................................... 51

3.6.24 Zinc Production......................................................................................................... 52

3.7 Energy Sector..................................................................................................................... 53

3.7.1 Oil and Gas Systems................................................................................................... 53

3.7.2 Underground Coal Mining.......................................................................................... 54

3.8 Waste Sector ...................................................................................................................... 57

3.8.1 Landfills...................................................................................................................... 57

3.8.2 Municipal Solid Waste Combustors........................................................................... 59

3.9 Agriculture (Stationary Fuel Combustion) ........................................................................ 60

3.10 Commercial Stationary Fuel Combustion........................................................................ 62

3.11 Residential Buildings....................................................................................................... 65

3.11.1 Single-Family Homes............................................................................................... 66

3.11.2 Multi-Family Residential Buildings ......................................................................... 67

References.................................................................................................................................... 72

Appendix A.................................................................................................................................. 77

Appendix B.................................................................................................................................. 78
1

Technical Support Document for Permit Thresholds for Greenhouse Gases

1. Purpose

The purpose of this document is to provide the background information that was used to 

support EPA's decision process on evaluating and selecting greenhouse gas (GHG) major source 

applicability thresholds for Prevention of Significant Deterioration (PSD) and Title V permitting

for EPA’s final rule “Prevention of Signficant Deterioration and Title V Greenhouse Gas 

Tailoring Rule”. The document describes the analysis used to estimate the number of existing 

and new facilities (e.g., industrial plant or commercial building) that would exceed different 

GHG emission threshold levels. The document also summarizes the results of this analysis for 

each sector. The results of this analysis served as one of the fundamental bases for evaluating 

administrative burdens at both existing permitting thresholds and for evaluating and selecting 

proposed alternative permitting thresholds to address administrative necessity concerns.

2. Overview

In order to support EPA's assessment of the administrative burden created by adding 

GHGs to existing Prevention of Significant Deterioration (PSD) and Title V permitting 

programs, it was necessary to develop information on the number of affected facilities at both the 

current permitting major source thresholds (generally, 100 tons per year for Title V and 100 or 

250 tons per year for PSD depending on the source category classification) and at alternative 

higher thresholds. An affected facility would be one who's annual emissions of the GHG equal 

or exceed the major source threshold being evaluated.

Eight threshold levels ranging from 100 to 100,000 tons per year of GHG emissions were 

evaluated. Some of the alternative thresholds evaluated are the same as ones (e.g., 25,000 tons 

per year CO2-equivalents) considered in previous studies and in support of EPA's proposed and 

final GHG mandatory reporting rules (GHG MRR, 74 FR 68, pp. 16447 – 16731 and 74 FR 209, 

pp. 56260-56519, respectively). One key difference between the emissions data developed for 

this analysis and the emissions data developed to support the proposed GHG MRR is that this 

analysis is based on a facility's "potential to emit" (PTE) while the proposed GHG reporting rule 

was based on "actual" emissions (i.e., the emissions a facility actually emits in a given year).

PTE is defined as the maximum capacity of a stationary source to emit a pollutant under its 

physical and operational design, including certain legal limitations, for example, on emissions or 

hours of operation. NSR and Title V programs both use PTE for defining major sources. The 

end result is generally that more facilities will exceed a given threshold on a PTE basis than on 

an actual basis. This is an important differentiation in terms of both evaluating the thresholds 

under this rule and when comparing the results to other threshold analysis, such as the supporting 

data for the EPA's GHG MRR.

Although the primary focus of this analysis was on the potential administrative burden 

associated with different GHG permitting emission levels as represented in terms of number of 

facilities potentially subject to permitting, information on GHG emissions from affected facilities 
2

was also collected to assess the relative coverage of national stationary source GHG emissions at 

the different threshold levels. While the environmental impact associated with the different 

GHG permitting levels was not used as the basis for the GHG applicability thresholds identified 

in the final GHG tailoring rule, the information on national emissions coverage provides a useful 

measure to consider the potential scope of the proposed alternative thresholds, their coverage of 

key GHG emission source categories, and whether they promote the environmental purposes of 

the PSD and Title V programs.

3. Emissions-based Threshold Analysis

3.1 General Description of Overall Approach

This section presents a general description of the overall approach EPA used to evaluate a 

range of permitting thresholds in terms of the number of sources affected, and amount of 

emissions covered.

EPA made use of earlier analyses performed to develop emission thresholds for the

proposed and final GHG MRR, or used the same data sources when additional analyses were 

required. EPA did not conduct primary research for this analysis, but instead relied on published 

research and publicly available government data, such as EPA's eGRID database of electric 

generating source emissions, Economic and Housing Census data, and Energy Information 

Agency (EIA) data on energy consumption.

3.1.1 Threshold Levels

EPA evaluated eight different GHG emission thresholds:

GHG Thresholds

(tons per year)

100

250

1,000

5,000

10,000

25,000

50,000

100,000

The first two thresholds are the current Clean Air Act major source criteria pollutant 

thresholds for the federal operating permit program under Title V (generally, 100 tpy for major 

source applicability), and the PSD construction permit program under Title I. Under PSD, a 

"major stationary source" is any source belonging to a specified list of 28 source categories 

which emits or has a PTE of 100 tpy or more, or any other source type which emits or has the 

potential to emit such pollutants in amounts equal to or greater than 250 tpy. 
3

The six additional thresholds cover the range of thresholds evaluated for the proposed 

GHG MRR, and add two additional thresholds at 5,000 and 50,000 tons per year. Like the Clean 

Air Act, the permit thresholds are based on U.S. short tons (tons) instead of metric tons (mtons).

There is a three-orders-of-magnitude range in the thresholds which reflects the much 

higher quantity of GHG emissions compared to criteria pollutant emissions from the primary

source of GHG emissions, fossil fuel combustion. For example, an uncontrolled natural gasfired boiler that emits 100 tons of NOx annually would at the same time emit about 100,000 tons 

of CO2.

The threshold analysis of source counts and emissions was done on a "potential to emit"

basis, because that is the basis that is relevant for the permitting requirements under PSD and 

title V. Potential emissions (in short tons) from each source were evaluated against the threshold 

levels in order to determine whether or not a source would be included in the threshold count. 

When a source was identified as being covered by a given threshold level, the actual emissions 

from that source were included to determine the emissions covered by the threshold. In other 

words, where summary tables present "Tg GHG Emissions Covered per Year" these are the 

actual emissions that would be covered by the threshold level, given the source count arrived at 

considering potential to emit emission levels.

3.1.2 Greenhouse Gases

EPA evaluated emissions of the major GHGs that are directly emitted by human activities

at the eight threshold levels. The GHGs evaluated are shown below in Table 1. For purposes of 

this analysis emissions were evaluated on both an individual GHG mass basis and CO2-

equivalent basis (CO2e). CO2e normalizes the different heat trapping capacities of the different 

GHGs to that of CO2. A quantity of a GHG is converted to a CO2e basis by multiplying the mass

of the compound emitted by its Global Warming Potential (GWP). The GWP is a metric that 

incorporates both the heat-trapping ability and atmospheric lifetime of each GHG relative to 

CO2. 
4

Table 1

Major GHGs Directly Emitted by Human Activities

Greenhouse Gas

Chemical Formula 

or Acronym

Global Warming 

Potential (GWP)*

Carbon dioxide CO2 1

Methane CH4 21

Nitrous oxide N2O 310

Perfluorocarbons PFCs Varies by compound

Hydrofluorocarbons HFCs Varies by compound

Sulfur hexafluoride SF6 23,900

* GWP values as codified in the EPA’s final GHG mandatory

reporting rule: Table A-1 to Subpart A of Part 98 – Global 

Warming Potentials, FR, Vol.74, No. 209, p. 56395. 

Sector descriptions contained in this document include a discussion of GHGs evaluated 

for each sector. If the analysis included more than one GHG, the description includes gasspecific counts as well as a CO2e count. The threshold analyses for stationary fossil fuel 

combustion were simplified by excluding CH4 and N2O emissions, because CO2 comprises over 

99 percent of GHG emissions from fossil fuel combustion.

3.1.3 Source Sectors

In this analysis EPA evaluated the same range of stationary source types with direct GHG 

emissions as identified in the proposed and final GHG MRR. The proposed GHG MRR source

categories were based on a comprehensive review of all U.S. source categories with GHG 

emissions, to include the categories that emit the most significant amount of GHG emissions. 

The stationary sources evaluated in this analysis can be grouped in the sectors shown below:

● Electricity Generation (facilities with fossil fuel-fired electric generating units);

● Industry (range of industries with process and combustion GHG emissions);

● Energy (oil and gas extraction, transport, and processing; underground coal mining);

● Waste Treatment (landfills and municipal solid waste incinerators);

● Agriculture (stationary fuel combustion);

● Commercial (stationary fuel combustion); and

● Residential (stationary fuel combustion).

A number of direct emission source types included in the GHG MRR analysis were not 

included in the potential to emit analysis because the GHG emissions from these sources were 
5

primarily fugitive emissions. Fugitive emissions are emissions which are not released, or could 

not be reasonably released, through a stack or vent. Under the PSD rules, fugitive emissions are 

only included in potential to emit estimates if the source is one of 28 listed PSD source 

categories. Excluded fugitive emissions sources are listed below:

● Electrical equipment SF6 emissions;

● Wastewater treatment plants not associated with one of 28 listed PSD source categories

(combustion is captured in the commercial sector analysis); and

● Agricultural manure management.

3.1.4 Potential to Emit Methodology

As noted earlier, the potential to emit (PTE) is the amount of emissions that can be 

emitted from a source operating at full capacity. The annual PTE is based on operation at full 

equipment capacity, 24 hours per day, 365 days per year (8,760 hours per year). For example, if 

a boiler has a maximum rated heat input capacity of ten million Btu per hour, the annual PTE for 

that boiler is the amount of emissions from burning 87,600 million Btu of fuel:

10 mmBtu/hr x 8,760 hrs/yr = 87,600 mmBtu/yr

Capacity information and annual GHG emissions were available for some of the source 

categories from analyses performed to support the GHG MRR. In some cases the supporting 

analyses had already calculated GHG emissions on a full capacity basis, in which case EPA

directly used those estimates as PTE estimates. Alternatively, some data from the supporting 

analysis estimated actual annual emissions using a baseline year. If capacity and baseline year 

production information was provided in the supporting data, EPA adjusted the source actual 

emissions estimate by the ratio of annual capacity to baseline production to estimate PTE. If 

capacity information was not available, EPA used capacity factors from other data sources to 

adjust actual emission estimates to PTE estimates. These capacity factors add varying 

uncertainty to the PTE estimate. Detailed descriptions of the different PTE calculation 

methodologies are included in the source descriptions in the following section.

Removal by pollution control equipment was considered in the PTE estimates, though 

control equipment removal was relevant in only a few cases (thermal oxidation of HPCs and 

CH4). Also, as noted earlier, fugitive emissions, were only included in the PTE estimates if the 

source was one of the 28 listed PSD source categories. For example, fugitive CH4 emissions 

from oil and gas transmission stations were not included in CH4 or CO2e emissions when 

comparing to the different thresholds, but were included for iron and steel plants.
6

3.1.5 New Construction

The source population data from the analyses supporting the GHG MRR, and other data 

sources provide information on existing sources and their emissions. The PSD and title V 

program requirements and applicability determinations, however, also apply to newly

constructed sources.

The general approach for estimating the annual number of newly constructed sources was 

to apply growth rates in the number of units or facilities in a source category to the number of 

existing facilities at the different thresholds. Growth rates were available from a variety of 

sources including Economic Census data, EIA energy survey data, and various EPA regulatory

impact analyses and information collection requests which require source population estimates. 

In some cases there was sufficient information to distribute new sources to different thresholds 

based on emission information specific to the new sources (electric generating, municipal solid 

waste combustors, and commercial stationary fuel combustion). Otherwise EPA assumed the 

same size and threshold distribution for new units as for existing units. For example, if the 

annual growth rate in a category was one percent, the number of existing facilities above a 

threshold were multiplied by the fractional growth rate to estimate the number of new facilities at 

that threshold per year.

EPA did not develop estimates for modifications to exsiting sources (which can be 

potentially subject to PSD requirements) as part of this threshold study; estimates for 

modifications were prepared under a separate burden analysis prepared for the final GHG 

tailoring rule and located in the final docket for the rulemaking1.

3.2 Threshold Summary Results

The resulting counts of affected stationary source facilities and the amount of actual 

GHG emissions covered at different PTE thresholds for all sectors are shown in the tables below. 

GHG emissions covered at each threshold are in Tg, which is equivalent to million metric tons. 

SI units were used for the covered emissions to be consistent with the EPA’s official U.S. GHG 

Inventory so that comparions could be made to the inventory in terms of emissions coverage at 

different applicability thresholds. The complete data for the sectors and subsectors are provided 

in supporting spreadsheets that accompany this report. These spreadsheets are identified in 

Appendices A and B.

 

1

See “Summary of Methodology and Data Used to Estimate Burden Relief and Evaluate Resource Requirements at 

Alternative Greenhouse Gas (GHG) Permitting Thresholds” contained in the public docket for the final tailoring rule 

at EPA-HQ-OAR-2009-0517.
7

Table 2

CO2e Threshold Summary -- All Stationary Source Sectors

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered

(Tg per year)

100 6,118,252 67,469 3,867

250 1,079,483 19,755 3,786

1,000 302,863 4,430 3,723

5,000 59,140 549 3,622

10,000 30,341 313 3,564

25,000 16,564 140 3,493

50,000 9,980 96 3,387

100,000 5,326 72 3,267

Table 3

CO2 Threshold Summary -- All Stationary Source Sectors

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered

(Tg per year)

100 6,113,861 67,469 3,651

250 1,075,078 19,755 3,570

1,000 298,527 4,430 3,513

5,000 55,313 549 3,413

10,000 26,836 313 3,357

25,000 13,637 139 3,293

50,000 8,109 96 3,212

100,000 4,226 72 3,114
8

Table 4

CH4 Threshold Summary -- All Stationary Source Sectors

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CH4 Emissions 

Covered 

(Tg per year)

100 4,201 0 7.807

250 3,851 0 7.759

1,000 2,887 0 7.321

5,000 1,042 0 4.740

10,000 466 0 3.697

25,000 138 0 2.234

50,000 34 0 1.185

100,000 3 0 0.211

Table 5

N2O Threshold Summary -- All Stationary Source Sectors

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

N2O Emissions 

Covered 

(Tg per year)

100 47 0 0.074

250 46 0 0.074

1,000 31 0 0.068

5,000 5 0 0.022

10,000 0 0 0

25,000 0 0 0

50,000 0 0 0

100,000 0 0 0
9

Table 6

High GWP Gases Threshold Summary -- All Stationary Source Sectors

GHG

GHG 

Threshold*

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

GHG Emissions 

Covered

(Tg per year)

HFC 100 3 0 0.001

HFC 250 3 0 0.001

HFC 1,000 1 0 0.001

HFC 5,000 and above 0 0 0

PFC 100 and above 0 0 0

SF6 100 and above 0 0 0

* Where a threshold is not listed for a particular GHG, threshold counts for that threshold and any higher 

thresholds can be assumed to be zero.

3.3 Electricity Generating Sector

Data Sources

The latest version of EPA's eGRID database (2006) was used to estimate the PTE of 

electricity generating facilities and counts of units above the different emission thresholds. The 

eGRID database includes year 2004 characteristics, operating information, and annual emissions 

(including CO2) for U.S. facilities that have a generation capacity greater than one MW, and sell 

electric power to the grid. 

A facility's PTE was estimated based on the eGRID generator table. The generator table, 

which is based on the 2004 EIA form 860 database, provides prime mover, generator nameplate 

capacity, and primary energy source (fuel type) for each generator down to 0.1 MW. To 

calculate PTE, we combined the nameplate capacity and primary fuel for each of the fossil-fired 

units with average fuel based prime mover heat rates (Btu/kWh) published by EIA (EIA, 2007).
10

Table 7

EGU Prime Mover Heat Rates

(EIA Electric Power Annual, Table A7, 2007)

Prime Mover Fuel Average Heat Rate (Btu/kWh)

Steam turbine

Coal 10,114

Gas 10,466

Oil 10,400

Simple 

combustion turbine

Gas 11,459

Oil 13,216

Combined cycle 

combustion turbine

Gas 7,445

Oil 11,015

Internal 

combustion engine

Gas 9,923

Oil 10,149

The eGRID database includes cogeneration plants and generating units at industrial 

plants that primarily supply electric power and steam to a host facility. We eliminated these 

units from the electric generation facility population based on North American Industry

Classification System (NAICS) code, so that the only facilities included were facilities with a 

NAICS code beginning with 22 (Utilities).

The generator-nameplate-heat-rate approach potentially underestimates PTE for 

cogeneration plants, where a portion of the burner heat input provides useful thermal energy in 

addition to electric output. This potential to underestimate PTE affects 321 of 2,237 or 14 

percent of facilities evaluated.

Methodology for Existing Facilities

Fuel combustion was the only source of GHG emissions considered for the electricity

generation sector. From the eGRID and EIA information EPA calculated a maximum annual 

fuel heat input based on 8,760 hours of operation for the combustors associated with the 

generator. This calculated maximum annual heat input was used with fuel combustion emission 

factors from the GHG MRR for the primary fuel, to calculate the facility PTE. The calculations 

covered 10,487 fossil fuel-fired generators with nameplate capacities down to 0.1 MW or 

100,000 kW.

EPA also did not evaluate fugitive CH4 emissions from facility coal piles. Fossil fuelfired steam electric plants with heat input greater than 250 mmBtu/hr heat input are one of the 28 

listed PSD source categories that include fugitive emissions when calculating PTE. However, 

the CO2 PTE from combustion alone for this size facility is about 225,000 tons per year. This is 
11

well over all of the emission thresholds considered in this analysis without consideration of the 

contribution of fugitive CH4.

New Units

The eGRID generator table includes an online year field. To determine the number of 

new units per year at different thresholds EPA counted generators online each year and totaled 

the emissions associated with those generators at the facility level over the 15-year period from 

1990 through 2004. Counts were made of the number of these facilities over the different PTE 

thresholds, and averaged over the 15 years to arrive at the number of new or modified facilities 

per year. 

Threshold Summary

The table below shows the facilities and emissions covered at the different emission 

thresholds based on the described methodology. There were a total of 2,237 facilities in the 

electric generation population, so all facilities and all emissions are covered up to the 5,000 ton 

PTE threshold. Almost all emissions (99.9 percent), and about 75 percent of facilities are 

covered at the highest 100,000 ton PTE threshold.

Table 8

CO2 Threshold Summary Results -- Electricity Generating Sector

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2Emissions 

Covered 

(Tg per year)

100 2,237 93 2,373

250 2,237 93 2,373

1,000 2,237 93 2,373

5,000 2,237 91 2,373

10,000 2,195 86 2,373

25,000 2,076 73 2,373

50,000 1,911 64 2,373

100,000 1,721 60 2,371

3.4 Industrial Sector

The industrial sector comprises establishments engaged in the mechanical, physical, or 

chemical transformation of materials, substances, or components into new products, and 

specifically includes businesses classified in Sectors 31 – 33 according to the North American 
12

Industry Classification System (NAICS). Industrial source greenhouse gases result from 

manufacturing processes as well as combustion processes. Because there is a great deal of 

variability within the sector, this technical support document includes industry-specific 

discussions after a general sector overview.

For the industrial sector, EPA considered the six individual greenhouse gases separately, 

and also prepared an analysis considering CO2e. In preparation of the GHG MRR, EPA 

identified 23 industrial sectors where the GHG emissions were significant; these sectors are 

listed in Table 9.
13

Table 9

Industrial Sectors and GHG Emissions

NAICS Code Industrial Sector CO2 CH4 N2O SF6 HFC PFC

325199 Adipic Acid Production X X

331312 Aluminum Production X X

325311 Ammonia Production X

327310 Cement Production X

334 Electronics Manufacturing X X X X

325193 Ethanol Production X

331112 Ferroalloy Production X X

3116 Food Processing X

327 Glass Production X

325120 HCFC-22 Production X X

Hydrogen Production X

331111 Iron and Steel Production X X

3314 Lead Production X

327410 Lime Manufacturing X

3314 Magnesium Production X X

325311 Nitric Acid Production X X

3251 Petrochemical Production X X

324110 Petroleum Refineries X X

325312 Phosphoric Acid Production X

3221 Pulp and Paper Manufacturing X

327910 Silicon Carbide Production X X

325181 Soda Ash Manufacturing X

325188 Titanium Dioxide Production X

3314 Zinc Production X

In addition, there are a large number of industrial establishments across all industrial 

sectors that emit less significant amounts of GHGs (primarily CO2) from stationary source fuel 

combustion. Combustion emissions from these establishments were analyzed under the 

Unspecified Industrial Stationary Combustion source category. 
14

3.4.1 Data Sources

There were several primary data sources used in preparation of the permit threshold 

analysis. EPA consulted analyses prepared in support of the GHG MRR for the 23 industrial 

sectors for which combustion, process and fugitive emissions were significant. These documents 

can be found in the docket numbered EPA-HQ-OAR-2008-0508. The TSDs contain industryspecific analyses of process, fugitive, and combustion emissions for industries. Supporting 

analyses used to prepare the TSDs are found in entries 0046.7 and 0046.8 of the GHG MRR

docket. These emissions estimate details were helpful in breaking down TSD emission estimates 

to compare facility-specific emissions against the additional threshold levels considered in the 

permit threshold analysis, including 100, 250, 5,000, and 50,000 tons per year.

Combustion emissions analyses for the Unspecified Industrial Stationary Combustion

sectors used data from the 2002 Manufacturing Energy Combustion Survey (MECS) and the 

U.S. Census Bureau's 2002 Economic Census. MECS is a survey of manufacturing and 

industrial energy uses and costs prepared by the EIA (EIA, 2007). Data is collected by 

manufacturing establishment through mailed questionnaires. The 2002 MECS data reflects 

responses accounting for approximately 98 percent of the manufacturing payroll, and reports

separate energy use estimates for 48 NAICS industrial sector groups. The MECS provided 

information on the amount of fuel burned in 2002 by sector on an employment basis. The 2002 

Economic Census data provided information on the number of establishments sorted by threedigit NAICS code and disaggregated into specific size categories based on employment (U.S. 

Census, 2004).

3.4.2 Potential to Emit

As mentioned earlier in this document, permit threshold analyses considered both actual 

emissions and PTE. When capacity information was not available, the analyses applied 

utilization rates from the Industrial Production and Capacity Utilization, Federal Reserve 

Statistical Release G-17 in order to adjust actual emissions to determine PTE emissions. These 

utilization rates are prepared quarterly with annual revisions, and are published on the web

(http://www.federalreserve.gov/releases/g17). The main data source for the industrial production 

and capacity utilization rates is the U.S. Census Bureau's Census of Manufactures. Data 

introduced from other Census Bureau publications include the Census of Services and the 

Services Annual Survey (for publishing) and selected Current Industrial Reports. Additional 

government source data include new annual data on minerals from the U.S. Geological Survey

(USGS) and updated deflators from the Bureau of Economic Analysis (BEA). In addition, the 

annual revisions include monthly production estimates that reflect updated seasonal factors and 

the inclusion of monthly source data that became available (or were revised) after the closing of 

the regular four-month reporting window. 

3.4.3 Methodology for New Units

To determine the number of new units per year, EPA compared the number of 

establishments by three-digit NAICS code in 1998 to the number of establishments by three-digit 

NAICS code in 2002, and determined an average annual growth rate for each three-digit NAICS 
15

code. The growth rates were applied to each threshold count to determine the number of annual 

new establishments per industry per threshold. If the growth rate was determined to be negative, 

EPA assumed that no new establishments would be added; however, establishments were not 

reduced to reflect negative growth rates. EPA also supplemented these growth rates with agency

estimates of expected new sources from various information collection requests (ICR) and 

regulatory impact analyses (RIA) efforts.

3.5 Methodology for Existing Unspecified Industrial Stationary Combustion Source 

Category Emissions

In order to determine establishment counts and emissions totals for the unspecified 

industrial stationary combustion sources, EPA used 2002 Economic Census data showing

manufacturing employment by NAICS code and Manufacturing Energy Consumption Survey

(MECS) data published by EIA. Calculating greenhouse gas emissions required determining 

energy consumption per employee by industry and applying emission factors specific to the 

consumption profile derived from MECS data.

The Economic Census data (2002) provide a count of establishments by employment 

category, where employment category is defined by number of employees (e.g., 1 – 4, 

5 – 9,...,500 – 999,...,more than 2,500). The MECS energy consumption data provide energy

consumption by industry. Both the employment data and the energy consumption data are

organized according to the NAICS codes. 

As part of this analysis, EPA calculated industry-specific GHG emission factors. The

factors were calculated by considering actual fuel consumption in 2002, as determined by EIA. 

Actual fuel consumed was multiplied by fuel-specific GHG emission factors to determine GHG

emissions by fuel type by industry. To simplify the analysis, EPA only included CO2 emissions 

and ignored CH4 and N2O in the CO2e calculations. CO2 makes up between 99.3 and 99.7 

percent of estimated CO2e emissions. Emissions for each fuel type were combined to determine 

total emissions for a sector. Total emissions per sector were divided by total energy

consumption per sector to determine a factor to calculate GHG emissions per mmBtu of energy

consumption specific to the industrial sector.

The GHG emission factors were then multiplied by the energy consumption per 

employee in order to determine emissions per employee. Multiplying the result by the average 

number employees per establishment, EPA determined total GHG emissions per establishment. 

The total emissions numbers were used to determine number of establishments and volume of 

emissions that would be caught by each of the permit thresholds under consideration. 

As discussed previously, a separate threshold analysis was conducted for 23 industrial 

sectors determined to have significant GHG emissions in the GHG MRR analysis. In order to 

quantify the unspecified industrial stationary combustion source emissions, the combustion 

emissions and establishment counts from 19 of these sectors were subtracted from the total 

industrial MECS analysis. For the remaining four industries, HCFC-22 production, hydrogen 

production, magnesium production, and nitric acid production, EPA could not readily isolate 

combustion emissions. For these industries, their establishment counts were subtracted from the 
16

unspecified industrial source threshold counts based on process emission threshold evaluations, 

assuming that any facility exceeding a threshold for process-based emissions would exceed the 

threshold regardless of their combustion CO2 emissions.

Potential to Emit

In order to determine potential to emit from the MECS and Economic Census numbers, 

EPA assumed a capacity utilization factor of 50%. There is a wide variety of generally smaller 

manufacturing sources included under this general source category. Based on comments we 

received on the proposed GHG tailoring rule, we are using a 50% capacity utilization rate for this 

final analysis to better reflect what can be deemed reasonable operation under normal conditions 

for facilities in these source categories. Sources may operate their combustion equipment at 

levels above and below this capacity utilization rate, but we believe the 50% utilization rate 

reflects a reasonable average rate across the variety of facilities represented in this category. 

New Units

EPA applied industry-specific growth rates to each sector and summed across sectors in 

order to determine number of new units.

Threshold Summary

Table 10

CO2e Threshold Summary -- Unspecified Industrial Stationary Combustion

GHG Threshold

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2eEmissions 

Covered 

(Tg per year)

100 172,142 546 372.307

250 112,659 319 367.636

1,000 64,535 239 357.855

5,000 20,785 83 318.759

10,000 12,215 61 289.198

25,000 5,875 18 245.579

50,000 3,272 12 206.881

100,000 958 2 145.106
17

3.6 Methodology for Existing Specific Industrial Sectors Considering Combustion, 

Process, and Fugitive Emissions

These analyses were based primarily on the GHG MRR TSDs and the supporting 

analyses, including facility specific emission information. The estimates considered each 

greenhouse gas separately. The GHG MRR TSDs included threshold counts and emissions 

calculations for 1,000, 10,000, 25,000, and 100,000 metric tons per year. Two steps were 

required for permit threshold consideration. First, emissions were recalculated in order to 

conduct the analysis in short tons for comparison to the permit thresholds. Second, the emissions 

were considered against the finer threshold stratification considered in the permit threshold 

analysis.

For the permit threshold analysis, EPA determined that if the GHG MRR analysis 

showed all of the establishments exceeded a threshold, after adjustment for short tons, all of the 

establishments exceeded any lower thresholds. However, where fewer than 100 percent of the 

establishments exceeded a threshold, additional analysis was required to compare emissions to 

the permit thresholds of 100, 250, 5,000, and 50,000 tons per year. EPA used the supporting

summaries for the GHG MRR which included facility-specific consumption, process, and 

fugitive emission reports in order to determine counts and emissions for each of the permit 

thresholds.

3.6.1 Adipic Acid Production

There are four Adipic Acid Production plants in the U.S., all of which are estimated to 

exceed the highest 100,000 metric tons per year emission threshold for CO2e on an actual 

emissions basis. Therefore all plants will also exceed all PTE thresholds on a CO2e basis. The 

CO2e emission estimate includes N2O process emissions that total about 5.9 million metric tons 

CO2e, and 3.4 million metric tons of CO2 from stationary fuel combustion sources. 

N2O

Individual plant production and emission estimates were not made available because of 

confidential business information (CBI) claims. However, from the Technical Support 

Document for the Adipic Acid Production Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases (EPA-HQ-OAR-2008-0508-0005), overall U.S. adipic acid production was 

estimated to total approximately one million metric tons in 2006. The smallest U.S. plant only

produced about two percent of the total. This plant, however, is the only plant that is 

uncontrolled. The three larger plants with the bulk of production have control equipment with 

N2O control efficiencies that range from 90 to 99 percent. 

The uncontrolled N2O emission factor is 300 kg N2O/mton adipic acid. Based on the two 

percent production share, this uncontrolled plant emitted about 6,000 metric tons of N2O (no 

GWP adjustment). This leaves about 13,100 metric tons of N2O from the three larger controlled 

plants. Two plants representing about 64 percent of production have control efficiencies in the 
18

range of 90 to 95 percent, and one plant with about 34 percent of production has control close to 

99 percent (EPA, 2001).

Assuming similar production shares today, the share of national production (which is 

assumed for this analysis to be equivalent to capacity) appears to range from 30 to 35 percent for 

the three plants. Therefore, emissions and PTE for the controlled plants range from to 4,000 

metric tons to 4,700 metric tons of N2O per year.

CO2

The CO2 emissions from fuel combustion can similarly be apportioned to the four plants. 

The smallest plant, with only two percent of national production, is estimated at CO2 emissions 

of 67,500 metric tons, and the next smallest, with 30 percent of national production, is estimated 

at 101,300 metric tons.

Potential to Emit

The PTE for each facility was assumed to be equivalent to the emissions based on the 

apportionment described above.

New Units

EPA assumed that no new plants would be constructed for this sector.

Threshold Summary

Table 11

CO2 Threshold Summary -- Adipic Acid Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 4 0 3.376

250 4 0 3.376

1,000 4 0 3.376

5,000 4 0 3.376

10,000 4 0 3.376

25,000 4 0 3.376

50,000 4 0 3.376

100,000 3 0 3.309
19

Table 12

N2O Threshold Summary -- Adipic Acid Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

N2O Emissions 

Covered 

(Tg per year)

100 4 0 0.019

250 4 0 0.019

1,000 4 0 0.019

5,000 1 0 0.006

10,000 0 0 0

25,000 0 0 0

50,000 0 0 0

100,000 0 0 0

Table 13

CO2e Threshold Summary -- Adipic Acid Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2eEmissions 

Covered 

(Tg per year)

100 4 0 9.298

250 4 0 9.298

1,000 4 0 9.298

5,000 4 0 9.298

10,000 4 0 9.298

25,000 4 0 9.298

50,000 4 0 9.298

100,000 4 0 9.298

3.6.2 Aluminum Production

The primary aluminum production process results in emissions of CO2 and PFCs. The 

reduction of the alumina occurs through electrolysis in a molten bath of natural or synthetic 

cryolite (Na3AlF6). The reduction cells contain a carbon lining that serves as the cathode. 

Carbon is also contained in the anode, which can be a carbon mass of paste, coke briquettes, or 
20

prebaked carbon blocks from petroleum coke. During reduction, most of the carbon in the anode 

is oxidized and released to the atmosphere as CO2.

Potential to Emit

CO2

The Technical Support Document for Process Emissions from Primary Production of 

Aluminum: Proposed Rule for Mandatory Reporting of Greenhouse Gases (EPA-HQ-OAR2008-0508-0006) apportioned CO2 emission estimates from the U.S. GHG inventory to the 13 

operating smelters based on each smelters share of total capacity. Operating smelter emissions 

were all above 100,000 tons of CO2, so no PTE estimate was required. Capacity information for 

the two idle smelters shows that these smelters are also capable of emitting over 100,000 tons of 

CO2 per year.

PFCs

The reduction cells also emit two PFCs: perfluoromethane (CF4) and perfluoroethane 

(C2F6). The GWPs of the two PFCs are 6,500 and 9,200 respectively. During the smelting 

process, when the alumina ore content of the electrolytic bath falls below critical levels required 

for electrolysis, rapid voltage increases occur, which are termed "anode effects." Anode effects 

cause carbon from the anode and fluorine from the dissociated molten cryolite bath to combine, 

and produce fugitive emissions of CF4 and C2F6. 

Anode effects released approximately 2.5 million metric tons of CF4 and C2F6 in 2006 as 

documented in the GHG MRR TSD. CF4 made up at least 85 percent of the combined emissions 

in 2006 (Inventory of U.S. GHG Emissions and Sinks: 1990 – 2007). These emissions on a 

CO2e basis are equivalent to about 410 short tons of combined emissions as PFC. The proposed 

GHG MRR TSD estimated CO2e emissions from primary aluminum smelters at full capacity. 

The largest smelter has 11 percent of U.S. operating capacity. Therefore the largest smelter has a 

PTE of not more than 45 tons of PFC, and no facilities have a PTE greater than 100 tons.

New Units

No new primary aluminum facilities are expected to be built. The growth rate in primary

metals from the Economic Census data is only about 0.4 percent.

Threshold Summary

Threshold summaries are displayed below for CO2 and CO2e. All facilities have a PFC 

PTE less than 100 tons per year on a PFC basis.
21

Table 14

CO2 Threshold Summary -- Primary Aluminum 

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

GHG Emissions 

Covered 

(Tg per year)

100 15 0 3.800

250 15 0 3.800

1,000 15 0 3.800

5,000 15 0 3.800

10,000 15 0 3.800

25,000 15 0 3.800

50,000 15 0 3.800

100,000 15 0 3.800

Table 15

CO2e Threshold Summary -- Primary Aluminum

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

GHG Emissions 

Covered 

(Tg per year)

100 15 0 3.951

250 15 0 3.951

1,000 15 0 3.951

5,000 15 0 3.951

10,000 15 0 3.951

25,000 15 0 3.951

50,000 15 0 3.951

100,000 15 0 3.951

3.6.3 Ammonia Production

EPA reviewed the proposed Supporting Data for Threshold Analysis Subpart E – W,

Greenhouse Gas Mandatory Reporting Rulemaking, March 10, 2009 (EPA-HQ-OAR-2008-

0508-0046.7) to determine actual emissions and calculate the potential to emit for 24 ammonia 

plants in operation. The analysis spreadsheet details CO2 actual emission calculations for each 
22

plant based on ammonia production and urea production, and CO2, CH4, and N2O emission 

calculations for stationary fuel combustion based on 2006 data. For purposes of permit threshold 

analysis, the CH4 and N2O emissions from combustion were not significant.

Potential to Emit

Capacity information in the spreadsheet is based on the engineering design capacity

adjusted for 340 days per year of effective production capability, using information provided by

the United States Geological Survey (USGS). The PTE estimates were made by multiplying the 

actual emission estimates by the ratio of annual ammonia capacity to annual ammonia 

production adjusted to 365 days a year of operation instead of 340. EPA assumed that ratio also 

held for stationary combustion units at the plant. 

New Units

EPA assumed that no new plants would be constructed for this sector.

Threshold Summary

Table 16

CO2e Threshold Summary -- Ammonia Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2eEmissions 

Covered

(Tg per year)

100 24 0 14.543

250 24 0 14.543

1,000 24 0 14.543

5,000 24 0 14.543

10,000 24 0 14.543

25,000 24 0 14.543

50,000 24 0 14.543

100,000 22 0 14.540

3.6.4 Cement Production

Process-related CO2 emissions from cement production are the second largest source of 

industrial CO2 emissions in the United States. Cement production is done in two stages. The 

first stage is clinker production. In clinker production, raw materials (primarily limestone) are 

heated to induce calcination and produce lime. Lime reacts with silica-containing materials and 
23

iron ore and aluminum to form clinker. During the process, CO2 is generated as a byproduct and 

released to the atmosphere. Also during clinker production, some of the clinker raw materials 

form partially or fully calcinated cement kiln dust instead of forming clinker, resulting in 

additional process-related CO2 emissions. In the second stage of the production process, the 

clinker is ground and mixed with gypsum and other materials to make cement.

Potential to Emit

The Technical Support Document for Process Emissions from Cement: Proposed Rule 

for Mandatory Reporting of Greenhouse Gases (EPA-HQ-OAR-2008-0508-0008) shows 107 

cement facilities in the U.S., 106 of which exceed all permit thresholds for CO2 (according to the 

TSD, the one facility that does not exceed the 100,000 tons per year threshold accounted for over 

90,000 metric tons of CO2e and approximately one-tenth of one percent of the cement industry

emissions in 2006).

New Units

Growth for the industrial sector was estimated at 0.4 percent, and as such, no additional 

facilities were included in this analysis.

Threshold Summary

Table 17

CO2e Threshold Summary -- Cement Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2eEmissions 

Covered 

(Tg per year)

100 107 0 86.83

250 107 0 86.83

1,000 107 0 86.83

5,000 107 0 86.83

10,000 107 0 86.83

25,000 107 0 86.83

50,000 107 0 86.83

100,000 106 0 86.74
24

3.6.5 Electronic Production

The Technical Support Document for Process Emissions from Electronics Manufacture 

(Semiconductors, MEMs, Liquid Crystal Displays, and Photovoltaics) (EPA-HQ-OAR-2008-

0508-0009) examined emissions of high GWP gases for semiconductor and related industry

plants. Emissions from stationary fuel combustion were not included in the source category

analysis, but were instead captured by the unspecified industrial stationary combustion analysis. 

EPA has followed this approach here as well.

Approximately one million metric tons of SF6 as CO2e were emitted from the 

semiconductor industry in 2006 (Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990

– 2007). This is equivalent to 46 short tons of SF6. The semiconductor industry uses multiple 

long-lived fluorinated gases in plasma etching and plasma enhanced chemical vapor deposition 

(PECVD) processes to produce semiconductor products. These include PFCs, which are also 

used as heat transfer fluids. Approximately 3.5 million metric tons of PFCs as CO2e were 

emitted from the semiconductor industry in 2006 (Inventory of U.S. Greenhouse Gas Emissions 

and Sinks: 1990 – 2007).

Table 18

Electronic Production PFC Emissions

Semiconductor PFC

2006 CO2e Emissions

(million mtons) PFC GWP

2006 PFC Emissions

(tons)

CF4 1.2 6,500 204

C2F6 2.2 9,200 264

C4F8 0.1 8,700 13

Total 3.5 -- 481

Potential to Emit

The Federal Reserve capacity utilization factor for the electronics industry in 2006 was 

79.8 percent. Based on this capacity utilization factor the PTE of all of the semiconductor plants 

combined is estimated at 56 tons of SF6 and 600 tons of PFC. 

EPA identified 216 facilities in the semiconductor-electronics sector. Of these, the 

largest facility emitted six percent of total semiconductor emissions on a CO2e basis (includes 

non-PFCs), which is a maximum of 30 tons of PFC. On a PTE basis, the largest facility would 

emit 36 tons, based on an assumption that the industry capacity is distributed similarly to 

emissions. Therefore no facility exceeds 100 tons per year on an actual or PTE basis for PFC.
25

New Units

Growth for the industrial sector was estimated at -1.8 percent, and as such, no additional 

facilities were included in this analysis. 

Threshold Summary

Electronics industry emissions from plant processes only exceed emission thresholds on a 

CO2e basis. Facility stationary fuel combustion emissions are not included in the threshold

comparisons for the industry.

Table 19

CO2e Threshold Summary -- Electronics Production 

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 199 0 5.948

250 191 0 5.947

1,000 159 0 5.934

5,000 109 0 5.819

10,000 88 0 5.701

25,000 65 0 5.399

50,000 54 0 5.100

100,000 22 0 3.417

3.6.6 Ethanol Production

In the proposed GHG MRR, EPA determined that the sources of GHG emissions at 

ethanol production facilities that must be reported under the proposed rule are stationary fuel 

combustion, onsite landfills, and onsite wastewater treatment. For the GHG MRR supporting 

analysis, data were unavailable to estimate facility emissions from these combined sources. 

Instead, data on stationary fuel combustion requirements for different plant capacities were used 

to estimate the minimum number of facilities that would meet each of the examined reporting 

rule facility-level thresholds. CO2 emissions from combustion constitute the majority of the 

GHG emissions from ethanol production and therefore provide an adequate measure for 

determining threshold counts. 
26

Table 20

Ethanol Fuel Combustion CO2e Emissions by Plant Size

(from the Proposed GHG MRR TSD Spreadsheet)

Ethanol Produced 

(wet milling process) 

(million gallons)

Coal Combustion Emissions

(mtons CO2e/year)

Natural Gas Combustion

Emissions

(mtons CO2e/year)

290 1,519,585 853,536

245 1,283,787 721,091

200 1,047,990 588,646

200 1,047,990 588,646

100 523,995 294,323

85 445,396 250,174

40 209,598 117,729

35 183,398 103,013

20 104,799 58,865

2.6 13,624 7,652

Table 21

Proposed Reporting Rule Threshold Analysis Results

Threshold CO2e

(tons per year)

Number of Existing 

Sources -- Actual Basis

Percent of Existing 

National Sources*

1,000 101 72%

10,000 93 66%

25,000 86 61%

100,000 43 31%

* National ethanol production source population was estimated at 140 plants nationwide.

Potential to Emit

The permit threshold PTE analysis relied on this same approach and data. Therefore CH4 

emissions from onsite landfills and wastewater treatment plant digesters were not included in the 

PTE analysis, and we did not estimate emission coverage at each threshold. Also, the analysis 

for the proposed GHG MRR did not evaluate thresholds of 100, 250, 5,000, and 50,000 tons per 

year. EPA assumed that all existing plants would exceed the 100 and 250 ton per year thresholds
27

based on fuel combustion associated with the wet milling process. For the 5,000 and 50,000

thresholds, EPA included the number of sources exceeding the next highest threshold. For 

example, the count of sources exceeding the 5,000 tons per year level only includes the sources 

exceeding the 10,000 ton threshold in the Technical Support Document for Ethanol Facilities:

Proposed Rule for Mandatory Reporting of Greenhouse Gases (EPA-HQ-OAR-2008-0508-

0010). 

New Units

EPA estimates that ten new ethanol production facilities will be built per year. 

Threshold Summary

Table 22

CO2e Threshold Summary -- Ethanol

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Sources Added

per Year

100 140 10

250 140 10

1,000 101 7

5,000 101 7

10,000 93 7

25,000 86 6

50,000 86 6

100,000 43 3

3.6.7 Ferroalloy Production

In evaluating ferroalloy production in the U.S., EPA considered actual production at six 

facilities, as published in the U.S. Inventory of Greenhouse Gas Emissions and Sinks: 1990 –

2007 for 2006, and the capacity to produce at three facilities for which production information 

was not published due to competitive concerns.

Potential to Emit

EPA's PTE calculations consider the Federal Reserve's 2006 monthly industrial capacity 

utilization estimates for the primary metals industry classification which shows utilization at 85.9 
28

percent for 2006. The PTE calculations do not affect the threshold analysis, because all facilities 

emit over 100,000 metric tons of CO2e per year. 

New Units

Applying the growth factor for the industrial sector, 0.4 percent, results in no additional 

facilities for the analysis.

Threshold Summary

Table 23

CO2 Threshold Summary -- Ferroalloy Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 9 0 1.717

250 9 0 1.717

1,000 9 0 1.717

5,000 9 0 1.717

10,000 9 0 1.717

25,000 9 0 1.717

50,000 9 0 1.717

100,000 9 0 1.717

Table 24

CH4 Threshold Summary -- Ferroalloy Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CH4 Emissions 

Covered 

(Tg per year)

100 3 0 0.0003

250 0 0 0
29

Table 25

CO2e Threshold Summary -- Ferroalloy Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2eEmissions 

Covered 

(Tg per year)

100 9 0 1.726

250 9 0 1.726

1,000 9 0 1.726

5,000 9 0 1.726

10,000 9 0 1.726

25,000 9 0 1.726

50,000 9 0 1.726

100,000 9 0 1.726

3.6.8 Food Processing

Food processing includes meat, poultry and fruit and vegetable processing. Emissions

derive from combustion and fugitive methane related to wastewater treatment. For purposes of 

this permit threshold analysis, EPA did not consider the fugitive methane from wastewater 

treatment because these are the only greenhouse gas emissions from the source category other 

than combustion, and food processing is not a listed PSD source category. Consequently, 

emissions from this subsector considered in this analysis were limited to combustion emissions 

and were calculated using the MECS approach. 

Potential to Emit

EPA used the Federal Reserve's 2004 capacity utilization factor of 79.3 percent for the 

food industry to calculate PTE emissions. 

New Units

In addition, new establishments were calculated assuming a continuation of the growth 

rate of 1.2 percent, as calculated using the methodology described earlier in this document. 
30

Threshold Summary

Table 26

CO2 Threshold Summary -- Food Processing

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 3946 47 16.848

250 2281 27 16.709

1,000 1499 18 16.379

5,000 1030 12 15.723

10,000 749 9 14.354

25,000 482 6 12.257

50,000 10 0 0.596

100,000 0 0 0

3.6.9 Glass Manufacturing

EPA used the Supporting Data for Threshold Analysis Subpart E – W, Greenhouse Gas 

Mandatory Reporting Rulemaking, March 10, 2009 (EPA-HQ-OAR-2008-0508-0046.7), to 

analyze emissions for permit thresholds from glass manufacturing. Annual fuel combustion and 

glass production are estimated for each plant based on 2004 estimated plant sales and 2002 

MECS energy intensity (energy per sales dollars). The spreadsheet shows CO2 emission 

estimates from industrial processes and stationary fuel combustion, as well as CH4 and N2O 

emission estimates from stationary fuel combustion. 

Potential to Emit

Plant capacities are not available in the spreadsheet. To estimate PTE, EPA divided the 

actual annual emissions by a capacity utilization factor of 0.50 or 50 percent.

New Units

EPA used an estimated annual growth rate of 0.4 percent for the nonmetallic mineral 

product manufacturing sector to determine the number of new units for this analysis. 
31

Threshold Summary

Table 27

CO2e Threshold Summary -- Glass Manufacturing

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2eEmissions 

Covered 

(Tg per year)

100 369 1 4.425

250 364 1 4.425

1,000 222 1 4.341

5,000 201 1 4.302

10,000 175 1 4.162

25,000 104 0 3.277

50,000 21 0 1.208

100,000 3 0 0.366

3.6.10 HCFC-22 Production

Chlorodifluoromethane (HCFC-22) is produced for use in refrigeration and air 

conditioning systems and as a chemical feedstock for manufacturing synthetic polymers. 

Because HCFC-22 depletes stratospheric ozone, its production for non-feedstock uses is 

scheduled to be phased out by 2020 under the U.S. Clean Air Act. Feedstock production,

however, is permitted to continue indefinitely.

A high global warming potential (GWP) greenhouse gas, trifluoromethane (HFC-23), is 

generated as a byproduct during the manufacture of HCFC-22. Emissions of HFC-23 in 2006 

were estimated to be 13.8 million metric tons on a CO2e basis from three HCFC-22 production 

plants. Estimates were based on the plants operating at capacity. Annual emissions in terms of 

both metric tons CO2e and tons HFC-23 are summarized in Table 30 below.
32

Table 28

HCFC-22 Production HFC-23 Emissions

HCFC-22 Production

2006 CO2e Emissions

(million metric tons) HFC GWP

2006 HFC 

Emissions

(short tons)

HFC-23 13.8 11,700 1,300

Source: Reporting Rule TSD

Potential to Emit

Confidential business information (CBI) claims on production information limited EPA's 

PTE analysis. The Technical Support Document for Emissions of HFC-23 from Production of 

HCFC-22: Proposed Rule for Mandatory Reporting of Greenhouse Gases (EPA-HQ-OAR2008-0508-0015) estimated that all three plants emit over 100,000 metric tons CO2e on a 

capacity basis by a factor of 85 or more, or a minimum of 800 short tons of HFC-23. These 

estimates did not account for HFC-23 capture and destruction at two of the three plants. 

Therefore, actual emissions at two of the plants will be lower, and can be limited through 

permitting. We assumed that all three plants exceed the 100 and 250 ton actual and PTE 

thresholds, and that one plant (uncontrolled) exceeds the 1,000 ton PTE threshold.

Because the TSD did not include estimates of CO2 emissions from fuel combustion, and 

the CBI claims noted above, the PTE analysis does not quantify fuel combustion emissions 

specifically for the three plants. Stationary fuel combustion emissions from the plants were 

instead captured under the analysis for unspecified industrial stationary combustion. 

New Units

U.S. production between 1990 and 2006 increased by 11 percent while emissions 

declined by 62 percent. The declines in emissions from control equipment and process changes 

offset the production increases. Therefore we did not estimate any new facilities or

modifications that would increase facility emissions more than 100 tons per year.
33

Threshold Summary

Table 29

HFC Threshold Summary -- HCFC-22 Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

HFC Emissions 

Covered 

(Tg per year)

100 3 0 0.001

250 3 0 0.001

1,000 1 0 0.001

5,000 0 0 0

Table 30

CO2e Threshold Summary -- HCFC-22 Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 3 0 13.848

250 3 0 13.848

1,000 3 0 13.848

5,000 3 0 13.848

10,000 3 0 13.848

25,000 3 0 13.848

50,000 3 0 13.848

100,000 3 0 13.848

3.6.11 Hydrogen Production

EPA estimated CO2 emissions from merchant hydrogen production using the process and 

combustion ratio of 8.62 tons of CO2 emissions per ton of hydrogen production. About 95 

percent of all hydrogen (not just merchant hydrogen) produced in the U.S. today is made from 

natural gas via steam methane reforming. In steam methane reforming fueled by natural gas 

combustion, the process and combustion emissions go up the same stack from the 

boiler/reformer unit. Because the emissions are predominately process emissions and because 
34

the natural gas combustion products are emitted from the same stack, EPA has treated all the 

emissions as process emissions.

Potential to Emit

EPA developed estimates assuming hydrogen production at capacity level. Therefore, no 

adjustment to the emissions estimates is needed to account for PTE emissions. 

New Units

Based on the industry growth factor of -0.1 percent for chemical manufacturing, EPA 

assumed that no new plants would be constructed.

Threshold Summary

Table 31

CO2 Threshold Summary -- Hydrogen Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 75 0 15.227

250 75 0 15.227

1,000 74 0 15.226

5,000 62 0 15.202

10,000 51 0 15.130

25,000 42 0 15.007

50,000 38 0 14.890

100,000 32 0 14.441

3.6.12 Iron and Steel Production

EPA used the Supporting Data for Threshold Analysis Subpart E – W, Greenhouse Gas 

Mandatory Reporting Rulemaking, March 10, 2009 (EPA-HQ-OAR-2008-0508-0046.7) for the 

proposed GHG MRR threshold analysis to determine process and combustion CO2 and process 

CH4. The iron and steel production source category includes taconite iron ore processing 

facilities, integrated iron and steel making facilities, electric arc furnace (EAF) steelmaking 

facilities that are not located at integrated iron and steel facilities, and coke oven facilities that 

are not located at integrated iron and steel facilities. Facility processes and facilities covered in 

the spreadsheet are shown in the table below.
35

Table 32

Iron and Steel Processes, Facilities, and Capacity Information

Iron and Steel Process Number of Facilities Capacity Information

Basic oxygen furnace (BOF) 18 Yes

Blast Furnace (BF) 17 Yes

Sintering 5 Yes

Coke ovens 18 Yes

Electric arc furnace (EAF) 92 No

Taconite furnace 8 Yes

Integrated steel plant fuel combustion* 19 No

Coke oven gas combustion* 9 No

EAF steel plant fuel combustion 92 No

* Six plants had emissions from coke oven gas combustion was included in integrated steel plant fuel 

combustion.

Potential to Emit

The analysis covered 130 plants, and in all cases, except for EAF plants, GHG emissions 

were estimated based on operations at plant capacity. For EAF plants, EPA used the 2007 

Federal Reserve industrial capacity utilization percentage of 86.6 percent for primary metal --

iron and steel production, to adjust estimated actual emissions to PTE. 

The spreadsheet contained emission CO2e estimates which included CO2, CH4, and N2O

emissions. Process CH4 emissions were backed out of the CO2e totals using the process CH4

emissions reported in the U.S. GHG Inventory, and apportioning these emissions to the different 

plants based on their capacity in those processes. N2O emissions are primarily related to fuel 

combustion and were not backed out for separate treatment. 

New Units

No new iron and steel facilities are expected to be built. The growth rate in primary

metals from the Economic Census data is only about 0.4 percent.
36

Threshold Summary

Table 33

CO2 Threshold Summary -- Iron and Steel Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per year

CO2 Emissions 

Covered 

(Tg per year)

100 130 0 85.150

250 130 0 85.150

1,000 130 0 85.150

5,000 129 0 85.148

10,000 128 0 85.141

25,000 123 0 85.057

50,000 116 0 84.831

100,000 113 0 84.655

Table 34

CH4 Threshold Summary -- Iron and Steel Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CH4 Emissions

Covered 

(Tg per year)

100 18 0 0.034

250 17 0 0.033

1,000 17 0 0.033

5,000 3 0 0.011

10,000 0 0 0
37

Table 35

CO2e Threshold Summary -- Iron and Steel Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 130 0 85.151

250 130 0 85.151

1,000 130 0 85.151

5,000 130 0 85.151

10,000 128 0 85.141

25,000 123 0 85.058

50,000 116 0 84.832

100,000 114 0 84.656

3.6.13 Lead Production

According to the 2006 U.S. Geological Survey (USGS), lead production in the U.S.

includes both the primary, direct smelting (one facility) and secondary lead production (16 

facilities). Process emissions of CO2 are a byproduct of the coke consumed during the smelting 

or reforming processes. EPA calculated total process emissions based on lead production as 

reported in the USGS. 

In the Supporting Data for Threshold Analysis Subpart E – W, Greenhouse Gas 

Mandatory Reporting Rulemaking (EPA-HQ-OAR-2008-0508-0046.7), combustion emissions 

are combined with process emissions to determine total actual emissions.

Potential to Emit

In order to determine PTE emissions, EPA considered the Federal Reserve's 2006 

monthly industrial capacity utilization estimates for primary metals industry classification which 

shows utilization at 85.9 percent for 2006, and adjusted to achieve 100 percent utilization. 

New Units

EPA assumed no new facilities would be added for the industry, given an expected 

growth rate of 0.4 percent per year for primary metal manufacturing industry.
38

Threshold Summary

Table 36

CO2e Threshold Summary -- Lead Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 17 0 0.861

250 17 0 0.861

1,000 17 0 0.861

5,000 17 0 0.861

10,000 16 0 0.855

25,000 13 0 0.799

50,000 12 0 0.761

100,000 1 0 0.089

3.6.14 Lime

The Supporting Data for Threshold Analysis Subpart E – W, Greenhouse Gas Mandatory 

Reporting Rulemaking, March 10, 2009 (EPA-HQ-OAR-2008-0508-0046.7) was also used to 

estimate GHG PTE for lime plants. 

Potential to Emit

To estimate PTE, EPA divided annual actual CO2 emissions from the calcining process 

and fuel combustion emissions of CO2, CH4, and N2O by regional capacity factors available in 

the spreadsheet for each plant. The capacity factors ranged from 43 to 136 percent.

New Units

EPA assumed no new facilities would be added for the industry.
39

Threshold Summary

Table 37

CO2 Threshold Summary -- Lime Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 89 0 27.262

250 89 0 27.262

1,000 89 0 27.262

5,000 89 0 27.262

10,000 89 0 27.262

25,000 86 0 27.237

50,000 66 0 26.533

100,000 60 0 26.180

3.6.15 Magnesium Production and Processing

The magnesium metal production (primary and secondary) and casting industry typically 

uses SF6 as a cover gas to prevent the rapid oxidation and burning of molten magnesium in the 

presence of air. A dilute gaseous mixture of SF6 with dry air and/or CO2 is blown over molten 

magnesium metal to induce and stabilize the formation of a protective crust. A small portion of 

the SF6 reacts with the magnesium to form a thin molecular film of mostly magnesium oxide and 

magnesium fluoride. The amount of SF6 reacting in magnesium production and processing is

being studied but presently assumed to be negligible, and therefore all SF6 used is assumed to be 

emitted into the atmosphere.

For the proposed GHG MRR Technical Support Document for Process Emissions from 

Magnesium Production and Processing: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, EPA reported that national annual SF6 emissions from magnesium 

production and processing totaled approximately 3.2 million metric tons CO2e in 2006. The 

facility population totaled 13 facilities that emitted 3.0 million metric tons CO2e. The SF6

emissions (no GWP adjustment) were 148 and 138 short tons respectively. Ten magnesium die

casting facilities accounted for 29 percent (44 tons), and primary and secondary production

accounted for 64 percent (96 tons) of the total emissions. Other small casting activities 

accounted for the remaining 7 percent (ten tons). 
40

Potential to Emit

EPA used the analysis in the TSD for the proposed GHG MRR, where EPA had 

evaluated thresholds of 1,000, 10,000, 25,000, and 100,000 metric tons per year. Facility-level 

information is not made publicly available because of confidential business information (CBI) 

claims. From that earlier analysis EPA estimated that the same number of facilities exceeded the 

100, 250, and 1,000 tons CO2e per year PTE threshold as determined in the GHG MRR TSD for 

the 1,000 metric tons per year threshold. In a similar fashion, EPA used the GHG MRR TSD 

facility counts at 10,000 metric tons CO2e per year to estimate facilities at the 5,000 tons per year 

PTE threshold, and 100,000 metric tons per year for the 50,000 tons CO2e per year PTE 

threshold. The permit threshold analysis did not include CO2 emissions from fuel combustion. 

That information was not available in the TSD for the proposed GHG MRR. 

On an SF6 mass basis, the average emissions per facility are only 11 tons of SF6, well 

below 100 tons per year. Therefore we assumed that none of the facilities have a potential to 

emit more than 100 tons per year of SF6.

New Units

EPA assumed no new units would be added for the sector.

Threshold Summary

Table 38

CO2e Threshold Summary -- Magnesium Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 13 0 2.955

250 13 0 2.955

1,000 13 0 2.955

5,000 11 0 2.94

10,000 11 0 2.94

25,000 11 0 2.94

50,000 9 0 2.781

100,000 9 0 2.781
41

3.6.16 Nitric Acid Production

EPA used the 2006 nameplate capacity (metric tons of HNO3 100 percent acid basis) for 

45 nitric acid plants and 2006 acid production from the GHG MRR TSD supporting spreadsheet 

(EPA-HQ-OAR-2008-0508-0046.7) to determine N2O emissions. 

Potential to Emit

The GHG PTE was calculated by multiplying actual N2O emissions as CO2e by the ratio 

of nameplate capacity to 2006 production. The permit threshold analysis, based on the GHG 

MRR TSD, does not include GHG emissions from co-located stationary combustion units. Also 

the permit threshold analysis does not account for overlap between facilities in the Nitric Acid 

and Ammonia categories, which have both ammonia and nitric acid production processes. 

New Units

EPA assumed no new units would be constructed for this sector.

Threshold Summary

Table 39

N2O Threshold Summary -- Nitric Acid Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

N2O Emissions 

Covered 

(Tg per year)

100 43 0 0.055

250 42 0 0.055

1,000 27 0 0.049

5,000 4 0 0.016

10,000 0 0 0

25,000 0 0 0

50,000 0 0 0

100,000 0 0 0
42

Table 40

CO2e Threshold Summary -- Nitric Acid Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 45 0 17.732

250 45 0 17.732

1,000 45 0 17.732

5,000 45 0 17.732

10,000 45 0 17.732

25,000 44 0 17.724

50,000 43 0 17.706

100,000 42 0 17.667

3.6.17 Petrochemical Production

EPA determined that the portion of the petrochemical production sector most relevant for 

permit threshold analysis includes the manufacture and production of acrylonitrile, carbon black, 

ethylene, ethylene dichloride, ethylene oxide, and methanol, because the IPCC considers 

production of greenhouse gases from these processes significant compared to other 

petrochemical processes. 

Emissions from the manufacturing processes vary significantly and process emissions

take many forms. Process emissions include direct oxidation of CO2, off-gassing of CH4 and

CO2, and the direct release of CO2 and CH4 from equipment leaks. Process emissions are the 

primary consideration for acrylonitrile, ethylene, and ethylene oxide processes. In addition, 

some processes require combustion of supplemental fuel. Both process and combustion

emissions are significant for carbon black and methanol processes. 

Potential to Emit

EPA's analysis assumed petrochemical production at the capacity level. Therefore, no 

adjustment to the emissions estimates is needed to account for PTE. 

New Units

Based on an industry growth factor of -0.1 percent for chemical manufacturing, EPA 

assumed that no new plants would be constructed.
43

Threshold Summary

Table 41

CO2 Threshold Summary -- Petrochemical Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 98 0 52.081

250 98 0 52.081

1,000 98 0 52.081

5,000 97 0 52.080

10,000 96 0 52.073

25,000 96 0 52.073

50,000 94 0 52.005

100,000 91 0 51.806

Table 42

CH4 Threshold Summary -- Petrochemical Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CH4 Emissions 

Covered 

(Tg per year)

100 55 0 0.130

250 52 0 0.129

1,000 37 0 0.121

5,000 5 0 0.035

10,000 1 0 0.010

25,000 0 0 0

50,000 0 0 0

100,000 0 0 0
44

Table 43

CO2e Threshold Summary -- Petrochemical Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 98 0 54.826

250 98 0 54.826

1,000 98 0 54.826

5,000 97 0 54.825

10,000 96 0 54.818

25,000 96 0 54.818

50,000 94 0 54.748

100,000 91 0 54.595

3.6.18 Petroleum Refineries

In developing the permit threshold analysis for petroleum refineries, EPA quantified CH4

process emissions from wastewater, fugitive, flares, and storage tanks. Process CO2 emissions 

derived from flares, hydrogen plant emissions, and sulfur plant emissions. In addition, on-site 

combustion emissions were calculated considering fuel consumed by type. 

Potential to Emit

EPA assumed that petroleum refineries were operating at capacity level. Therefore, no 

adjustment to the emissions estimates was needed to account for PTE. 

New Units

According to the ICR prepared for the New Source Performance Standard (NSPS), EPA 

expects that no new refineries will be built over the next few years.
45

Threshold Summary

Table 44

CO2 Threshold Summary -- Petroleum Refineries

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 150 0 202.947

250 150 0 202.947

1,000 150 0 202.947

5,000 150 0 202.947

10,000 149 0 202.938

25,000 146 0 202.887

50,000 137 0 202.575

100,000 129 0 202.065

Table 45

CH4 Threshold Summary -- Petroleum Refineries

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CH4 Emissions 

Covered 

(Tg per year)

100 129 0 0.083

250 109 0 0.080

1,000 31 0 0.042

5,000 0 0 0
46

Table 46

CO2e Threshold Summary -- Petroleum Refineries

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 150 0 204.897

250 150 0 204.897

1,000 150 0 204.897

5,000 150 0 204.897

10,000 149 0 204.888

25,000 146 0 204.835

50,000 137 0 204.513

100,000 129 0 203.988

3.6.19 Phosphoric Acid Production

Phosphoric acid is produced by combining sulfuric acid and phosphate rock. CO2 is 

emitted when the limestone component of phosphate rock reacts with the sulfuric acid. 

Potential to Emit

When these process emissions are combined with combustion emissions, all 14 plants 

have emissions that exceed the highest threshold level; consequently, no PTE analysis was 

required.

New Units

Based on an industry growth factor of -0.1 percent for chemical manufacturing, EPA 

assumed that no new plants would be constructed.
47

Threshold Summary

Table 47

CO2 Threshold Summary -- Phosphoric Acid Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 14 0 3.838

250 14 0 3.838

1,000 14 0 3.838

5,000 14 0 3.838

10,000 14 0 3.838

25,000 14 0 3.838

50,000 14 0 3.838

100,000 14 0 3.838

3.6.20 Pulp and Paper Manufacturing

Permit threshold analysis for this sector is focused on the energy intensive, fugitive 

emitting pulp, paper, and paperboard manufacturing subsectors. Process emissions include CO2

which is emitted in the recovery cycle at kraft and soda facilities associated with the chemical 

pulp process. The CO2 emitted from kraft mill lime kilns originates from two sources: (1) fossil

fuels burned in the kiln; and (2) conversion of calcium carbonate (or "lime mud") generated in 

the recovery process to calcium oxide.

The bulk of the emissions considered derive from combustion. Many boilers use biomass 

fuel, and the burning of spent pulping liquors to produce steam for facility processes is 

considered biomass combustion for the GHG MRR. The emissions numbers considered for the 

permit threshold analysis are non-biogenic (net of any biogenic emissions). Considering only

non-biogenic emissions, 96.5 percent of the facilities and 99.7 percent of the emissions are 

captured by all of the thresholds proposed for consideration of the permit threshold rule. 

Potential to Emit

Because 99.7 percent of emissions were captured at even the highest threshold, no 

additional PTE estimate was calculated in this analysis.
48

New Units

Based on an industry growth factor of -2.5 percent for paper manufacturing, and previous 

EPA analysis for the pulp and paper NSPS ICR, EPA assumed that no new plants would be 

constructed.

Threshold Summary

Table 48

CO2e Threshold Summary -- Pulp and Paper Manufacturing

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 425 0 57.700

250 425 0 57.700

1,000 425 0 57.700

5,000 425 0 57.700

10,000 425 0 57.700

25,000 425 0 57.700

50,000 422 0 57.688

100,000 410 0 57.527

3.6.21 Silicon Carbide Manufacturing

In 2006, one facility produced silicon carbide in the U.S. Silicon carbide is primarily an 

industrial abrasive manufactured from silica sand or quartz and petroleum coke. Approximately

35 percent of the carbon from the petroleum coke is retained with the silicon carbide, and the rest 

is emitted as both CO2 and CH4. In addition, emissions from combustion account for 

approximately ten percent of total emissions. 

Potential to Emit

Emissions from this plant exceed all permit threshold levels; as a result, EPA did not 

consider PTE calculations. 

New Units

EPA assumed there would be no new facilities constructed.
49

Threshold Summary

Table 49

CO2 Threshold Summary -- Silicon Carbide Manufacturing

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 1 0 0.101

250 1 0 0.101

1,000 1 0 0.101

5,000 1 0 0.101

10,000 1 0 0.101

25,000 1 0 0.101

50,000 1 0 0.101

100,000 1 0 0.101

Table 50

CH4 Threshold Summary -- Silicon Carbide Manufacturing

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CH4 Emissions 

Covered 

(Tg per year)

100 1 0 0.0004

250 1 0 0.0004

1,000 0 0 0
50

Table 51

CO2e Threshold Summary -- Silicon Carbide Manufacturing

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 1 0 0.109

250 1 0 0.109

1,000 1 0 0.109

5,000 1 0 0.109

10,000 1 0 0.109

25,000 1 0 0.109

50,000 1 0 0.109

100,000 1 0 0.109

3.6.22 Soda Ash Production

Soda Ash production emissions were nearly evenly split between process and combustion 

emissions. Process emissions result from calcining trona ore to produce soda ash. 

Potential to Emit

PTE emissions were calculated based on the capacities of the production units. 

New Units

In 2006, there was a glut of soda ash in the domestic market; EPA assumed no new units 

would be constructed.
51

Threshold Summary

Table 52

CO2e Threshold Summary -- Soda Ash Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 5 0 3.121

250 5 0 3.121

1,000 5 0 3.121

5,000 5 0 3.121

10,000 5 0 3.121

25,000 5 0 3.121

50,000 5 0 3.121

100,000 5 0 3.121

3.6.23 Titanium Dioxide Production

EPA used USGS as the source for production capacity for the eight facilities that 

produced titanium dioxide in 2006.

Potential to Emit

Emissions were assumed to represent PTE operating levels. 

New Units

EPA assumed that no new plants would be constructed. 
52

Threshold Summary

Table 53

CO2e Threshold Summary -- Titanium Dioxide Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 8 0 3.686

250 8 0 3.686

1,000 8 0 3.686

5,000 8 0 3.686

10,000 8 0 3.686

25,000 8 0 3.686

50,000 8 0 3.686

100,000 7 0 3.628

3.6.24 Zinc Production

The Zinc production emissions and facility count estimates include process and 

combustion emissions associated with primary smelting and secondary recycling facilities. 

Potential to Emit

For PTE estimates, EPA considered the Federal Reserve's 2006 monthly industrial 

capacity utilization estimates for primary metals industry classification which shows utilization 

at 85.9 percent for 2006, and adjusted to achieve 100 percent utilization. 

New Units

EPA assumed that no new units would be constructed. 
53

Threshold Summary

Table 54

CO2e Threshold Summary -- Zinc Production

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 9 0 0.852

250 9 0 0.852

1,000 9 0 0.852

5,000 9 0 0.852

10,000 8 0 0.843

25,000 5 0 0.802

50,000 5 0 0.802

100,000 5 0 0.802

3.7 Energy Sector

3.7.1 Oil and Gas Systems

In consideration of the permit thresholds, EPA considered the Fugitive Emissions 

Reporting from the Petroleum and Natural Gas Industry: Background Technical Support 

Document (EPA-HQ-OAR-2008-0508-0023). This document details combustion emissions and 

fugitive emissions from offshore petroleum and natural gas facilities, onshore natural gas 

processors, onshore natural gas transmission, underground natural gas storage, and liquid natural 

gas storage. EPA determined that oil and gas exploration, development, transmission, and 

distribution are not listed PSD source categories, and therefore fugitive emissions from these 

activities were not considered for PSD applicability as it relates to major source thresholds. 

EPA's analysis focused on combustion emissions from these sources.

Potential to Emit

EPA used a capacity utilization figure of 50 percent to determine PTE emission estimates 

and counts. This rate is meant to reasonably represent an average utilization rate across a variety 

of combustion equipment types used in the oil and gas industry subsectors described above.

New Units

EPA determined new units based on a growth factor of 1.0 percent for the sector. 
54

Threshold Summary

Table 55

CO2e Threshold Summary -- Oil and Gas Systems

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 4762 48 88.264

250 4762 48 88.264

1,000 4762 48 88.264

5,000 3722 37 86.192

10,000 3095 31 83.619

25,000 2496 25 79.386

50,000 1045 10 56.949

100,000 387 4 32.750

3.7.2 Underground Coal Mining

GHG emissions from underground coal mining include CH4 fugitive emissions released 

from the coal seam and surrounding rock during mining and post-mining activities (coal bed 

CH4), and fuel combustion emissions of CO2, CH4, and N2O. Fugitive CH4, emissions are 

captured and vented by ventilation systems and degassing systems. Captured and vented CH4

emissions from active mines were considered in the PTE analysis. Because underground coal 

mining is not one of the 28 PSD source categories for which fugitive emissions were required to 

be included in the emissions determination, fugitive emissions from post mining operations, 

surface mines, and inactive mines were not included in the permit thresholds analysis. 

The Technical Support Document for Underground Coal Mines: Proposed Rule for 

Mandatory Reporting of Greenhouse Gases (EPA-HQ-OAR-2008-0508-0032) identified 612 

active underground coal mining facilities but analysis of CH4 emissions was limited to 128 

"gassy" mines where CH4 monitoring was already in place (due to existing CH4 emissions above 

Mine Safety and Health Administration (MSHA) threshold levels). The U.S. GHG Inventory

(EPA, 2008) reports that 233 underground coal mines (including 133 gassy mines) ventilated 

CH4 in 2007. Fuel combustion emission estimates for the GHG MRR TSD from all underground 

coal mines, based on U.S. Census energy use data, were found to comprise between one and

three percent of total CO2e emissions, with coal bed CH4 accounting for the bulk of GHG 

emissions.
55

In addition to the emissions data on the 128 gassy mines contained in the GHG MRR 

TSD, EPA considered combustion emissions from 289 bituminous underground coal mines, 

using U.S. Census data from 2002.

Potential to Emit

CH4

CH4 emission estimates that were developed for the GHG MRR TSD were used for both 

actual emissions and PTE emissions permit threshold analysis. EPA assumed that venting and 

degassing were continuous throughout the year; therefore, actual emission estimates equal PTE

emission estimates. The estimates considered 128 gassy mines, which were assumed to be the 

largest emitters of vented CH4. The smallest mine of this group had annual CH4 emissions of 26 

tons; therefore EPA assumed that the annual CH4 emissions from the 105 vented mines that were 

not included in the TSD analysis were less than 26 tons. 

CO2

CO2 emissions were estimated in the same manner as for other Unspecified Industrial 

Stationary Combustion categories, based on the ICF analysis (ICF, 2007) using the MECS

approach. Emissions were estimated based on Census information including fuel consumption 

per employee and the distribution of establishments by the number of employees. PTE was 

estimated by using a capacity utilization factor of 86.3 percent as published by the Federal 

Reserve.

New Units

The number of underground bituminous coal mines in the U.S. is on the decline. EIA 

data show that only Colorado had an increase in the number of underground coal mines between 

2006 and 2007 (EIA, 2008). The EIA data show that overall the number of underground coal 

mines decreased from 2006 to 2007 by eight percent; consequently, EPA assumed no new 

underground mines would be built. http://www.eia.doe.gov/cneaf/coal/page/acr/table1.html.
56

Threshold Summaries

Threshold summary tables are shown below for CH4 (vented fugitive emissions), CO2 

(fuel combustion), and CO2e (vented fugitive CH4 and combustion CO2).

Table 56

CO2 Threshold Summary -- Underground Coal Mining

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 238 0 0.783

250 202 0 0.778

1,000 63 0 0.692

5,000 30 0 0.577

10,000 30 0 0.577

25,000 0 0 0

Table 57

CH4 Threshold Summary -- Underground Coal Mining

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 110 0 1.586

250 110 0 1.586

1,000 110 0 1.586

5,000 53 0 1.420

10,000 38 0 1.361

25,000 24 0 1.147

50,000 13 0 0.784

100,000 1 0 0.105
57

Table 58

CO2e Threshold Summary -- Underground Coal Mining

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2e Emissions 

Covered 

(Tg per year)

100 238 0 39.520

250 238 0 39.520

1,000 126 0 33.945

5,000 124 0 33.943

10,000 123 0 33.936

25,000 103 0 33.606

50,000 78 0 32.800

100,000 55 0 31.241

3.8 Waste Sector

3.8.1 Landfills

The landfill PTE analysis includes both municipal solid waste (MSW) landfills and onsite 

industrial landfills associated with pulp and paper and food processing. The analysis used a 

modification of the landfill emission modeling approach described in the Technical Support 

Document for the Landfill Sector: Proposed Rule for Mandatory Reporting of Greenhouse 

Gases (EPA-HQ-OAR-2008-0508-0034), which was used for the proposed GHG MRR threshold 

analysis. Like the GHG MRR analysis, the permit threshold PTE analysis did not include onsite 

industrial landfills for ethanol processing facilities or industrial land application systems. 

GHG Emissions

Decomposition of waste in landfills generates CH4 and CO2. The amount of CH4

generated from a given landfill is a function of several factors: the total amount of waste 

disposed in the landfill; the characteristics of the waste; and the climatic conditions. The amount 

of CH4 emitted is the amount of CH4 generated minus the amount of CH4 oxidized by aerobic 

microorganisms in the landfill cover material. Also subtracted from the total is the amount of 

CH4 that is destroyed by combustion of the vented gas. The CO2 produced by decaying waste is 

not considered an anthropogenic emission, and is not counted in GHG emission totals. Likewise, 

CO2 resulting from the combustion of landfill CH4 is not accounted for as an anthropogenic 

emission under international accounting guidance.

According to the 2008 U.S. Inventory, MSW landfills emitted 111.2 million metric tons 

CH4 (CO2e basis) in 2006. The majority of the CH4 emissions from on-site industrial landfills 
58

occurs at pulp and paper facilities and food processing facilities. In 2006, these landfills emitted 

14.6 million metric tons CO2e

Potential to Emit

The methodology used for the proposed GHG MRR threshold analysis was also used to 

estimate CH4 generation rates and emissions in 2006 for the PTE analysis. A landfill-specific 

model developed by EPA to support its proposed GHG MRR was used to estimate CH4

generation and potential generation from municipal landfills. The generation estimate was 

adjusted with assumptions on oxidation in landfill cover, and destruction by combustion for 

energy recovery or flaring. The industrial landfill generation and emission estimates are based 

on the U.S. GHG Inventory. Industrial landfills were assumed not to have energy recovery or 

flaring, so there was no difference between generation and emissions.

New Units

EPA did not estimate the number of new facilities added each year with CH4 emissions 

above the different thresholds due to the time delay between landfill construction and emission 

generation. 

Threshold Summary

Table 59

CO2e Threshold Summary -- Landfills

GHG Threshold 

(tons per year)

Number of 

Existing Sources

CO2e Emissions 

Covered 

(Tg per year)

100 4,131 125.621

250 4,117 125.619

1,000 4,053 125.592

5,000 3,564 124.552

10,000 3,265 122.788

25,000 2,701 115.937

50,000 1,684 92.340

100,000 967 72.722
59

Table 60

CH4 Threshold Summary -- Landfills

GHG Threshold 

(tons per year)

Number of 

Existing Sources

CH4 Emissions 

Covered 

(Tg per year)

100 3,885 5.973

250 3,562 5.931

1,000 2,692 5.539

5,000 981 3.274

10,000 427 2.326

25,000 114 1.087

50,000 21 0.401

100,000 2 0.106

3.8.2 Municipal Solid Waste Combustors

The threshold analysis for the proposed GHG MRR included municipal solid waste 

combustors (MWC) in the general stationary fuel combustion category. The analysis used the 

eGRID database, which is discussed in the PTE methodology description for electric generating 

units. 

Data and Methodology

EPA used the latest version of the eGRID database (2006) to estimate the PTE of MWC 

facilities and counts of facilities above the different emission thresholds. The eGRID database 

includes year 2004 characteristics, operating information, and annual CO2 emissions for U.S. 

facilities that have a generation capacity greater than one MW and sell electric power to the grid. 

By using eGRID, EPA assumed that all MWC facilities sell power to the grid.

Potential to Emit

EPA identified 75 MWC facilities based on the generator primary fuel in the generator 

table (primary fuel equals MSW) in the eGRID database. The eGRID database contains CO2

annual emissions estimates for the facilities. For CO2 emissions, eGRID uses a standard 

assumption that 70 percent of the heat value of the waste stream comes from renewable materials 

and 30 percent comes from nonrenewable materials. The renewable fraction has a CO2 emission 

rate of zero; therefore, the PTE threshold analysis is based on the nonrenewable or fossil fraction 

assumption. EPA estimated PTE by dividing the annual emissions from eGRID by the eGRID 

plant capacity factor.
60

New Units

To determine the number of new per year at different thresholds, EPA counted the 

number of generators online each year, and totaled the nameplate capacity for each online year. 

This information was compared to the total facility nameplate capacity, and the PTE for the 

increased capacity was calculated by multiplying the facility PTE by the fraction of nameplate 

capacity associated with the new generators. EPA counted the facilities that exceeded the PTE 

thresholds during each period, and computed a 15-year average to determine the number of new 

or modified facilities per year. 

Threshold Summary

Table 61

CO2 Threshold Summary -- Municipal Solid Waste Combustors -

GHG Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 75 2 6.255

250 75 2 6.255

1,000 75 2 6.255

5,000 75 2 6.255

10,000 75 2 6.255

25,000 74 2 6.24

50,000 67 1 6.071

100,000 40 1 4.958

3.9 Agriculture (Stationary Fuel Combustion)

The analysis for the Agriculture sector was limited to stationary fuel combustion CO2

emissions from internal combustion diesel engine generators. Fugitive emissions of CH4 from 

enteric fermentation, and CO2, CH4, and N2O from manure management were not included 

because farms and related operations are not in the 28 PSD source categories that require 

quantification of fugitive emission PTE for determining major source status, and because of the 

large uncertainties and lack of information on determining what component of the noncombustion emissions at agricultural operations would be defined as non-fugitive for PSD 

purposes. Fuel combustion for building space heating and other farm purposes were not 

included in the estimates, but would be a component of farm PTE. 
61

Data and Methodology

EPA used the 2007 ICF analysis to estimate the number of farms covered by the different 

thresholds (ICF, 2007). Emissions from diesel generators on farms were estimated using data on 

the average generator size in Delaware (EEA, 2004), and data on energy use on farms for nontransport/non-machinery motors (Brown and Neal 2005). Using these data, EPA estimated the 

number of diesel generators on farms and apportioned the generators across farm sizes, assuming 

no farm has more than one generator. 

Potential to Emit

EPA assumed that a high proportion of farms would run the generators infrequently, and 

a smaller proportion would have a generator as the only power source, requiring nearly constant 

operation. EPA used this distribution to determine actual and potential emissions, with PTE 

emissions based on the assumption that the generators ran 24 hours per day, 365 days per year.

EPA recognizes that this approach underestimates the PTE for all farm stationary fuel 

combustion sources, because it is limited to diesel engine generators used primarily to run pumps 

and motors, and does not include additional sources such as fuel combustion for drying and 

curing, space heating, and water heating. 

New Units

New generator installations were estimated based on information in the Regulatory

Impact Analysis (RIA) for the spark ignition stationary combustion engine NSPS and area 

NESHAPS (EPA, 2007). The on-farm engine population of diesel generators used for irrigation 

increased four percent between 1998 and 2003, or about 0.8 percent annually. 
62

Threshold Summary

Table 62

CO2 Threshold Summary -- Farm Stationary IC Engines

CO2 Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Engines Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 37,351 299 0.512

250 37,351 299 0.512

1,000 0 0 0

5,000 0 0 0

10,000 0 0 0

25,000 0 0 0

50,000 0 0 0

100,000 0 0 0

3.10 Commercial Stationary Fuel Combustion

Data Source

EPA used EIA's Commercial Building Energy Consumption Survey (CBECS) to estimate 

commercial sector stationary fuel combustion GHG emissions and PTE. CBECS is a national 

sample survey that collects information on the stock of U.S. commercial buildings, their energyrelated building characteristics, and their energy consumption and expenditures. Commercial 

buildings include all buildings in which at least half of the floor space is used for a purpose that 

is not residential, industrial, or agricultural; thus, the source category includes building types that 

might not traditionally be considered "commercial," such as schools, correctional institutions, 

and buildings used for religious worship. The CBECS survey is conducted every four years and 

the most recent survey was completed for 2003.

The CBECS survey sample was designed so that survey responses could be used to 

estimate characteristics of the entire nationwide commercial building stock. The 2003 survey

selected 6,955 potential case buildings for sampling. The sampling procedures resulted in 5,215 

completed building interviews for a response rate of 82 percent. To make national estimates

from the sample data, EIA calculated base sampling weights for each building (the reciprocal of 

the probability of that building being selected into the sample). In other words, the base 

sampling weight is the number of national buildings represented by the sampled building. The 

base weight was further adjusted to account for nonresponsive bias. 
63

EIA publishes summary tables from the survey, and posts "microdata" files on the EIA 

website. The CBECS microdata consist of the 5,215 sampled building records, which each 

correspond to a single sampled building. For each building, these files contain information such 

as the building size, climatic region, census region, year constructed, types of energy used, and 

energy consumption and expenditures. These individual building microdata records are also the 

basis for the summary tables published by EIA. 

Emissions Methodology

EPA used the CBECS microdata to estimate commercial building emissions and 

populations above emission thresholds. Each of the 5,215 microdata records corresponds to a 

single sampled building. EIA has made available 20 different data files of the microdata records 

which contain a wide range of information on characteristics and energy use for each building.

EPA's analysis relied on guidance provided by EIA on how to use the data. As noted 

above, the CBECS sample was designed so that survey responses could be used to estimate 

characteristics of the entire commercial building stock nationwide. The table below provides 

examples from EIA on how to calculate national commercial building characteristics from the 

sample building data.

Table 63

EIA Website Examples

To Find the National 

Estimate for: Do This...

And You

Should Get...

Total number of buildings Sum ADJWT8 (weight factor) 4,858,749.82 

(or 4,859 thousand) 

Total number of office 

buildings

Sum ADJWT8 for cases where PBA8 (building code) = "02" 823,805.47 

(or 824 thousand) 

Total floor space Create a new variable (weighted square footage) by 

multiplying ADJWT8 by SQFT8 (floor space) for each case, 

then sum this new variable

71,657,900,522 

(or 71,658 million ft2) 

Total floor space in 

buildings with air 

conditioning

Sum the new weighted square footage variable (see above) 

for cases where COOL8 (air conditioning) = "1"

63,559,999,624 

(or 63,560 million ft2) 

Total electricity 

consumption in KWh 

Create a new variable (weighted electricity consumption) by 

multiplying ADJWT8 by ELCNS8 (electricity consumption) 

for each case, then sum this new variable

1,043,175,710,751 

(or 1,043 billion kWh)

Source: http://www.eia.doe.gov/emeu/cbecs/cbecs2003/public_use_2003/cbecs_pudata2003.html.

EIA calculated base sampling weights for each surveyed building (these are the 

reciprocal of the probability of that building being selected into the sample). Therefore, a 

building with a base weight of 1,000 represents itself and 999 similar but unsampled buildings in 
64

the total building stock. The base weight is further adjusted to account for non-response bias. 

The variable "ADJWT8" in the data file is the final weight. The ADJWT8 weight factor is used 

as described in Table 63 to extrapolate the survey sample to a national scale for any value. In 

order to obtain a national value each sample building's value must be multiplied by the building's 

weight (ADJWT8). All of the weighted values are then summed. 

2003 CO2 Emissions

EPA calculated the CO2 emissions for each of the 5,215 buildings based on the annual 

natural gas and oil consumption reported for the building. For national emission estimates and 

counts of buildings with annual CO2 emissions over any threshold, EPA multiplied the base 

weights by the sample emission totals to determine the national estimate of buildings with 

emissions over the threshold.

Potential to Emit

EPA estimates that commercial buildings operate at 15 percent of capacity. EPA 

considered several sources in making the PTE factor determination: 

● A report prepared by Energy and Environmental Analysis, Inc. for Oak Ridge National 

Laboratory describing the industrial and commercial boiler population in the United 

States (EEA, 2005). The report estimated an average commercial boiler capacity factor

of 16 percent.

● Reports on cooking equipment energy use by the Food Service Technology Center in 

California suggesting that the cooking equipment in food service establishments operate 

at about ten percent of a theoretical maximum capacity based on 8,760 hours per year 

(Pechan, et.al, 2008).

● A study of Los Angeles dry cleaners performed by the Pollution Prevention Education 

and Research Center (PPERC) in 2004 which demonstrates that dry cleaners operate 

boilers at about 10 to 15 percent of maximum capacity over a normal year (Pechan, et al., 

2008).

New Buildings

The CBECS data identifies the year the sampled buildings were constructed. We used 

the construction year information to identify the number of new buildings built each year in the 

1990 to 2003 period. Counts of the average number of these buildings built per year were then 

made at the different emissions and PTE thresholds.

Threshold Summary

The count of buildings and emissions at the threshold levels for the entire sector are 

shown in the table below. Threshold results by commercial building categories (e.g., offices, 

public assembly, schools) are provided in Appendix B. 
65

Table 64

CO2 Threshold Summary -- Commercial Sector Stationary Fuel Combustion

CO2 Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

100 1,355,921 22,123 119.262

250 731,477 12,041 105.306

1,000 172,654 2,922 69.885

5,000 18,167 196 29.384

10,000 5,660 96 17.765

25,000 1,161 7 8.790

50,000 600 3 6.003

100,000 51 2 1.012

3.11 Residential Buildings

Data Sources

EPA used residential fuel consumption data from EIA's Residential Energy Consumption 

Survey, and multi-family building and unit data from U.S. Census (Census) surveys to estimate 

CO2 emissions and PTE for fuel combustion at single and multi-family residential properties. 

The RECS is a national area-probability sample survey that collects energy-related data for 

occupied primary housing units. The most recent 2005 survey collected data from 4,382 

households in housing units statistically selected to represent the 111.1 million housing units in 

the United States. RECS data are tabulated for the four Census regions, the nine Census 

divisions, and for the four most populous States -- California, Florida, New York, and Texas.

The RECS sample was designed so that survey responses could be used to estimate 

characteristics of the national stock of occupied housing units. In order to arrive at national 

estimates from the RECS sample, EPA calculated base sampling weights for each housing unit

as the reciprocal of the probability of that building being selected into the sample. Therefore, a 

housing unit with a base weight of 10,000 represents itself and 9,999 similar, but not sampled 

housing units in the total stock of occupied residential housing units. The base weight is further 

adjusted to account for non-response bias. Ratio adjustments were also used to ensure that the 

RECS weights add up to Census Current Population Survey estimates of the number of 

households.

The RECS data are provided at the housing unit level, and not at the building level. EPA 

used additional data from the Census on multi-family building population characteristics to 

estimate total property emissions and PTE for multi-unit properties. Census data were from two 
66

sources: the Property Owner and Manager Survey (POMS, 1996) and the American Housing 

Survey (AHS, 2005).

3.11.1 Single-Family Homes

The RECS data was used directly to estimate CO2 emissions from fossil fuel combustion 

at single-family housing units for space heating, water heating, and appliances. EPA assumed 

that each unit in an attached single-family building was a separate source, with combustion 

equipment under different ownership. 

The annual energy consumption by fuel (1,000 Btus) for the surveyed unit was multiplied 

by the fuel CO2 emission factor to estimate annual emissions. Total single-family unit emissions 

for the entire country were calculated by multiplying CO2 emissions for each units by the base 

sampling weight. 

Potential to Emit

The PTE for a single-family unit was calculated by dividing the CO2 emissions from the 

unit by a capacity factor of 0.1. This factor was estimated by comparing the average annual CO2

emissions per heated floor space area per hour by climate zone, to required heat input capacity. 

The required heat input capacity was based on rule of thumb heating system requirements for the 

different climate zones. The table below shows the average Btu/ft

2

-hour from the RECS data 

and Heating Requirement (Btu/ft

2

) by climate zone. A heating system efficiency of 80 percent

was used to estimate the required space heating capacity. 

Table 65

Single-Family Detached and Attached

Households with Fossil Fuel-Fired Space Heating

(from RECS, 2005)

Households

(millions)

Climate

Zone(s)

Heating Degree 

Day Range

Average Annual Fuel 

Consumption

(Btu/ft

2

-hour)

Space Heating 

Requirement* 

(Btu/ft

2

)

6.8 5 > 7,000 4.8 50 – 60

16.7 4 5,500 – 7,000 5.4 45 – 50

17.0 3 4,000 – 5,499 4.6 40 – 45

18.9 1 and 2 < 4,000 3.8 Zone 2: 35 – 40

Zone 1: 30 – 35

* Heating requirement ranges are from www.acdirect.com/systemsize.php.
67

3.11.2 Multi-Family Residential Buildings

Emission Rates

As noted earlier in the Data Source section, the RECS data are on an individual unit 

basis, not building or property basis, so a different approach was required for multi-family units 

where EPA assumed common ownership of the property fuel combustion equipment. In order to 

estimate property emissions and the number of properties above different emission and PTE 

thresholds, EPA combined the RECS data with data from the POMS and AHS.

From the RECS data, EPA first calculated average residential unit CO2 emissions for the 

two most common fuels (natural gas and oil) by multi-family category. These are shown in the 

table below. 

Table 66

Multi-Family Residential Unit -- Average Annual CO2 Emissions

(from RECS, 2005)

Multi-Family Category

(number of units)

Natural Gas Space Heating

(tons CO2/residential unit-year)

Fuel Oil Space Heating

(tons CO2/residential unit-year)

2 to 4 units 4.8 8.3

5 or more units 3.0 8.9

EPA also obtained annual CO2 emission rates from an EPA analysis that was based on 

Lawrence Berkeley National Lab (LBNL) modeling studies. Those rates were estimated for old 

and new building units (see Table 67). The pre-1980 building estimate compares with the 

overall average from the RECS data. The post-1980 building estimates are much lower, 

particularly for units burning fuel oil.

Table 67

Multi-Family Residential Unit -- Average Annual CO2 Emissions

(from 2008 EPA Analysis based on LBNL, 1997)

Multi-Family Category

(building age)

Gas Serviced Units

(tons CO2/residential unit-year)

Fuel Oil Serviced Units

(tons CO2/residential unit-year)

Pre-1980 building 4.75 7.17

Post-1980 building 2.65 3.87
68

Existing Property Characteristics

Information on the distribution of multi-family properties by number of units per property 

was taken from the 1995 – 1996 POMS. The data are aggregated by different housing unit 

ranges. The table below shows the property size distribution from unpublished POMS data 

(NMHC Quick Facts -- Apartment Stocks (http://www.nmhc.org)). The POMS data were for 

privately owned housing only and excluded public housing projects (about 13,500 buildings and 

1,326,000 units). For our estimates, the building numbers were adjusted to current (2005) levels 

based on the RECS unit data (unit ratio of RECS to POMS). EPA assumed the same unit 

distribution in the adjustment. 

Table 68

Multi-Family Residential Property Size Distribution

(from National Multi-Housing Council tabulation of unpublished POMS data 1995 – 1996)

Number of Rental 

Units on Property

Number of Properties 

(1995 – 1996)

Number of Units 

(1995 – 1996)

Average Number 

of Units per 

Property

2 1,558,700 3,093,200 2

3 336,030 1,025,900 3

4 341,350 1,436,800 4

5 – 9 281,500 1,897,700 7

10 – 14 70,390 862,280 12

15 – 19 36,780 602,260 16

20 – 29 38,000 916,750 24

30 – 39 18,166 604,240 33

40 – 49 14,431 702,790 49

50 – 99 26,694 2,009,400 75

100 – 199 19,804 2,952,300 149

200 – 299 7,775 1,948,400 251

300 – 399 2,966 1,058,800 357

400 – 499 1,307 605,130 463

500 – 749 723 431,360 597

Over 750 307 437,670 1,426

Total 2,754,923 20,584,980
69

The adjusted POMS size distribution and average number of units in each category were 

combined with information from RECS on the percentage of units that use gas or oil for space 

heating. The gas and oil emission factors from the previous tables were applied to the average 

number of units in each property size category by fuel to estimate property annual CO2

emissions. 

For our final estimates we used the LBNL based emission factors for post-1980 

buildings, over the RECS based factor. We found that these lower emission factors resulted in 

total emissions more in line with the total based on all RECS units and residential sector 

estimates in the U.S. Greenhouse Gas Inventory. The RECS-based factors combined with the 

POMS property distribution data resulted in a larger overestimate in overall category annual 

emissions. The lack of information on the building population over 50 units, and lack of 

information on the correlation between unit emissions and the building/property size are large 

sources of uncertainty in the estimates at thresholds above 1,000 tons.

Potential to Emit

PTE was estimated using the same ten percent capacity factor as used for the single 

family residential units

New Properties

The AHS data provided information on new construction used to estimate the number of 

new buildings and new units with natural gas space heating that were constructed in the 1999 –

2005 period. To simplify the analysis, EPA ignored the limited use of fuel oil for space heating 

in new units. 

The AHS data provided separately the number of new buildings with gas space heating 

per year, and a size distribution for all new buildings per year. The AHS size distribution 

stopped at 50 and larger, and was slightly different in other categories from the POMS data. 

EPA adjusted the distribution based on the POMS distribution and then used the same emission 

and capacity factor approach as used for existing units.
70

Table 69

American Housing Survey New Building Data

Building Size: 

Number of Units 

per Building

Number of New 

Buildings per Year

(1999 – 2005)

(thousands)

Fraction of All 

New Buildings 

per Year 

(1999 – 2005)

New Gas Buildings

per Year

(1999 – 2005)

(thousands)

Number of New 

Gas Buildings 

per Year

2 6.3 0.22

16.0

3,468

3 – 4 5.4 0.19 2,995

5 – 9 6.1 0.21 3,389

10 – 19 6.0 0.21 3,310

20 – 29 3.1 0.11 1,734

30 – 49 1.0 0.03 552

50 or more 1.0 0.03 552

Total 29.0 1.00 16.0 16,000
71

Threshold Summary

Table 70

CO2 Threshold Summaries -- Residential Sectors

Threshold 

(tons per year)

Number of 

Existing Sources

Number of New 

Facilities Added 

per Year

CO2 Emissions 

Covered 

(Tg per year)

Multi-Family Residential

100 610,500 11,300 54.285

250 137,000 6,400 42.192

1,000 51,200 1,100 32.399

5,000 7,800 120 14.934

10,000 1,400 20 4.933

25,000 160 3 1.392

50,000 20 0 0.006

100,000 0 0 0

Single-Family Residential

100 3,925,000 33,000 51.408

250 45,350 515 1.670

1,000 0 0 0

Total Residential Sector

100 4,535,500 44,300 105.693

250 182,350 6,915 43.862

1,000 51,200 1,100 32.399

5,000 7,800 120 14.934

100,00 1,400 20 4.933

25,000 160 3 1.392

50,000 20 0 0.006

100,000 0 0 0
72

References

Brown, E., and Elliott, R.N., On-Farm Energy Use Characterizations, Report Number IE052, 

©American Council for an Energy-Efficient Economy, Washington, D.C., March 2005. 

http://www.aceee.org/pubs/ie052full.pdf

E.H. Pechan & Associates, Inc., Perrin Quarles Associates, Inc., and Alpine Geophysics, LLC, 

Greenhouse Gas (GHG) Emissions and New Source Review, Work Assignment No. 1-06, EPA 

Contract No. EP-D-07-097, April 10, 2008 (EPA-HQ-OAR-2008-0318-0080).

Environmental Energy and Analysis, Inc. (EEA), Characterization of the U.S. Industrial 

Commercial Boiler Population, submitted to Oak Ridge National Laboratory, May 2005

(EPA-HQ-OAR-2008-0318-0005).

http://www1.eere.energy.gov/industry/distributedenergy/pdfs/characterization_industrial_comme

rical_boiler_population.pdf

Energy and Environmental Analysis, Inc. (EEA), World of Distributed Generation in Delaware,

February 2004. 

http://www.eeainc.com/rrdb/DGRegProject/Documents/DEDGWorld.pdf

Federal Register, 74 FR 16447, Mandatory Greenhouse Gas Reporting Regulations; Proposed

Rule, Washington, D.C., April 10, 2009.

Federal Reserve, Statistical Release G17. Industrial Production and Capacity Utilization. 

http://www.federalreserve.gov/releases/g17/About.htm

ICF, International, Memorandum from Chris Steuer, Marian Van Pelt and Robert Lanza 

regarding Methodology Description for Industrial Sector GHG Threshold Analysis, November 2, 

2007 (EPA-HQ-OAR-2008-0318-0079).

Lawrence Berkeley National Laboratory (LBNL). Energy Data Sourcebook for the U.S. 

Residential Sector. Prepared by Energy Analysis Program, Environmental Energy Technologies 

Division, LBNL, University of California, Berkeley, CA, September 1997. 

http://enduse.lbl.gov/info/Pubs95_99.html

National Multi-Housing Council (NMHC), Quick Facts Apartment Stock: Distribution of 

Apartments by Size of Property, NMHC tabulation of unpublished data from the U.S. Census 

Bureau's 1995 – 1996 Property Owners and Managers Survey. 

http://www.nmhc.org/

U.S. Census Bureau (2006), American Housing Survey for the United States: 2005. 

http://www.census.gov/hhes/www/housing.html.

U.S. Census Bureau (2004), 2002 Economic Census, August 2004. 

http://www.census.gov/econ/census02/
73

U.S. Census Bureau (1998), 1995 Property Owners and Managers Survey, 1998. 

http://www.census.gov/hhes/www/housing/poms/poms.html

U.S. Energy Information Administration (EIA), Electric Power Annual, 2007, January 21, 2009. 

http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html

U.S. Energy Information Administration (EIA), Annual Energy Review 2005, DOE/EIA-0384, 

July 1, 2006.

U.S. Energy Information Administration (EIA), 2005 Residential Energy Consumption Survey, 

February 2009. 

http://www.eia.doe.gov/emeu/recs/recspubuse05/pubuse05.html

U.S. Energy Information Administration (EIA), 2003 Commercial Building Energy Consumption 

Survey, December 2006.

http://www.eia.doe.gov/emeu/cbecs/cbecs2003/public_use_2003/cbecs_pudata2003.html

U.S. Energy Information Administration (EIA), 2002 Manufacturing Energy Consumption 

Survey, January 2007. 

http://www.eia.doe.gov/emeu/mecs/contents.html

U.S. Environmental Protection Agency (EPA), Inventory of U.S. Greenhouse Gas Emissions and 

Sinks: 1990 – 2007, April 2009, US EPA 430-R-09-004. 

http://www.epa.gov/climatechange/emissions/usinventoryreport.html

U.S. Environmental Protection Agency (EPA), Supporting Data for Threshold Analysis Subpart 

E – W, Greenhouse Gas Mandatory Reporting Rulemaking, March 10, 2009 (EPA-HQ-OAR2008-0508-0046.7).

U.S. Environmental Protection Agency (EPA), Supporting Data for Threshold Analysis Subpart 

X – PP, Greenhouse Gas Mandatory Reporting Rulemaking, March 10, 2009 (EPA-HQ-OAR2008-0508-0046.8).

U.S. Environmental Protection Agency (EPA), Emissions & Generation Resource Integrated 

Database (eGRID) 2004, May 2007. 

http://www.epa.gov/cleanenergy/energy-resources/egrid/index.html

U.S. Environmental Protection Agency (EPA), Regulatory Impact Analysis for the Stationary 

Spark-Ignition New Source Performance Standard (SI NSPS) and New Area Source NESHAP,

December 2007, US EPA 452/R-07-015. 

http://www.epa.gov/ttn/atw/nsps/sinsps/sinspspg.html

U.S. Environmental Protection Agency (EPA), Draft U.S. Adipic Acid and Nitric Acid N2O 

Emissions 1990 – 2020: Inventories, Projections and Opportunities for Reductions, November 

2001. 

http://www.epa.gov/nitrousoxide/pdfs/adipic_nitric_n2o.pdf
74

U.S. Environmental Protection Agency (EPA), Climate Change Division, Fugitive Emissions 

Reporting from the Petroleum and Natural Gas Industry: Background Technical Support 

Document, undated, FR publish date: March 26, 2009 (EPA-HQ-OAR-2008-0508-0023).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Adipic Acid Production Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0005).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for Process Emissions from Primary Production of Aluminum: Proposed Rule for 

Mandatory Reporting of Greenhouse Gases, February 4, 2009 (EPA-HQ-OAR-2008-0508-

0006).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Ammonia Production Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0007).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for Process Emissions from Cement: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 28, 2009 (EPA-HQ-OAR-2008-0508-0008).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for Process Emissions From Electronics Manufacture (Semiconductors, MEMs, 

Liquid Crystal Displays, and Photovoltaics), January 29, 2009 (EPA-HQ-OAR-2008-0508-

0009).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for Ethanol Facilities: Proposed Rule for Mandatory Reporting of Greenhouse 

Gases, February 4, 2009 (EPA-HQ-OAR-2008-0508-0010).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Ferroalloy Production Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0011).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Glass Manufacturing Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0014).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for Emissions of HFC-23 from Production of HCFC-22: Proposed Rule for 

Mandatory Reporting of Greenhouse Gases, February 06, 2009 (EPA-HQ-OAR-2008-0508-

0015). 

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Hydrogen Production: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, August 5, 2008 (EPA-HQ-OAR-2008-0508-0016).
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U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse 

Gases, September 9, 2008 (EPA-HQ-OAR-2008-0508-0017).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Landfill Sector: Proposed Rule for Mandatory Reporting of Greenhouse 

Gases, February 4, 2009 (EPA-HQ-OAR-2008-0508-0034).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Lead Production Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0018).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Lime Manufacturing Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0019).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for Process Emissions from Magnesium Production and Processing: Proposed Rule 

for Mandatory Reporting of Greenhouse Gases, February 10, 2009 (EPA-HQ-OAR-2008-0508-

0020).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Petrochemical Production Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, September 9, 2008 (EPA-HQ-OAR-2008-0508-0024).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Petroleum Refining Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, September 9, 2008 (EPA-HQ-OAR-2008-0508-0025).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Phosphoric Acid Production Sector: Proposed Rule for Mandatory Reporting 

of Greenhouse Gases, February 20, 2009 (EPA-HQ-OAR-2008-0508-0026).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Pulp and Paper Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, February 11, 2009 (EPA-HQ-OAR-2008-0508-0027).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Silicon Carbide Production Sector: Proposed Rule for Mandatory Reporting 

of Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0028).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Soda Ash Manufacturing Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0029).
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U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Titanium Dioxide Production Sector: Proposed Rule for Mandatory Reporting 

of Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0031).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for Underground Coal Mines: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, February 4, 2009 (EPA-HQ-OAR-2008-0508-0032).

U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Technical Support 

Document for the Zinc Production Sector: Proposed Rule for Mandatory Reporting of 

Greenhouse Gases, January 22, 2009 (EPA-HQ-OAR-2008-0508-0033).
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Appendix A

Sector Permit Threshold Counts and Emissions by GHG

The listed electronic spreadsheet files contain the permit threshold counts and emissions 

for each sector and subsector by GHG. These listed files are included in separate files in the 

docket (EPA-HQ-OAR-2009-0517). Please refer to the following file names for additional 

information on specific sectors and GHGs:

● GHG Data for Final Tailoring Rule Development - CO2e.xls

● GHG Data for Final Tailoring Rule Development - CO2.xls

● GHG Data for Final Tailoring Rule Development - CH4.xls

● GHG Data for Final Tailoring Rule Development - N2O.xls

● GHG Data for Final Tailoring Rule Development - HFC.xls

● GHG Data for Final Tailoring Rule Development - PFC.xls

● GHG Data for Final Tailoring Rule Development - SF6.xls
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Appendix B

Commercial Building Sector -- Permit Threshold Results by Commercial Category

Please refer to the electronic file "Commercial Building Category CO2 Permit Threshold 

Results.xls." in the docket for EPA-HQ-OAR-2009-0517.
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