Trends in Emissions of Fluorinated GHGs Reported 

under the Greenhouse Gas Reporting Program:

Patterns and Potential Causes

Deborah Ottinger (Corresponding Author) a, Mollie Averyt b, Deborah Harris c, and Sally 

Rand d

a Climate Change Division, Office of Atmospheric Programs (6207J), Environmental Protection Agency, 

1200 Pennsylvania Avenue NW., Washington, D.C. 20460, USA; telephone number: (202) 343-9149; fax 

number: (202) 343-2338; email address: ottinger.deborah@epa.gov

b ICF International, 1725 I Street N.W., Suite 1000, Washington D.C., 20006, USA; telephone number: 

(202) 862-1569; fax number: (202) 862-1144; email address: Mollie.Averyt@icfi.com

c ICF International, 1725 I Street N.W., Suite 1000, Washington D.C., 20006, USA; telephone number: 

(202) 862-1574; fax number: (202) 862-1144; email address: Deborah.Harris@icfi.com

d Climate Change Division, Office of Atmospheric Programs (6207J), Environmental Protection Agency, 

1200 Pennsylvania Avenue NW., Washington, DC 20460; telephone number: (202) 343-9739; fax 

number: (202) 343-2338; email address: rand.sally@epa.gov

 
2

Trends in Emissions of Fluorinated GHGs Reported under the Greenhouse Gas 

Reporting Program: Patterns and Potential Causes

Deborah Ottinger (Corresponding Author) a

, Mollie Averyt b, Deborah Harris b, and Sally 

Rand a

a Climate Change Division, Office of Atmospheric Programs (6207J), Environmental Protection Agency b ICF International

Abstract: Since 2012, industrial users of fluorinated GHGs have been reporting their 

emissions of these GHGs under the U.S. EPA’s Greenhouse Gas Reporting Program 

(GHGRP). This paper discusses the trends observed in these emissions over three 

years of reporting (for emissions that occurred from 2011 through 2013), including

patterns and potential explanations. Some industries, for example, manufacturers and 

users of electrical transmission and distribution equipment, have experienced significant 

reductions in reported emissions since the beginning of the program. Analysis indicates 

that these reductions are concentrated among relatively large emitters. Possible 

explanations for these reductions include increased awareness by facilities of the 

magnitude of their emissions (both in absolute terms and relative to the emissions of 

similar facilities) and/or concerns regarding public perception of those emissions. The 

paper also compares the emission reductions observed over the life of the GHGRP to 

those observed over the lives of various voluntary emission reduction Partnerships to 

which many GHGRP reporters have belonged for more than a decade, examining 

whether the different conditions under which data are reported and publicized under the 

two programs have had an impact on emission reduction patterns. 

Keywords: fluorinated greenhouse gas, emissions, trends, patterns, reductions

1. Introduction

Fluorinated greenhouse gases (F-GHGs) are greenhouse gases (GHGs) that contain 

fluorine. F-GHGs include (1) perfluorocarbons (PFCs); (2) hydrofluorocarbons (HFCs); 

(3) sulfur hexafluoride (SF6); (4) nitrogen trifluoride (NF3); and (5) other F-GHGs that are 

used for applications such as heat transfer.1 F-GHGs, while emitted in lower quantities 

than other more common non-carbon dioxide (CO2) GHGs (e.g., methane), have high 

global warming potentials (GWPs) and long atmospheric lifetimes (IPCC, 2007). The

observed atmospheric concentrations of these GHGs have increased rapidly in recent 

decades (see Figure 1 for examples).

 1 Investigating trends in GHG emissions requires converting emission quantities to a common carbon 

dioxide equivalent basis, which requires chemical-specific global warming potentials (GWPs). Many of the 

“other F-GHGs” do not have known GWPs. GWPs continue to be evaluated and are periodically 

evaluated and published by the International Panel on Climate Change (IPCC) and the U.S. 

Environmental Protection Agency.
3

Figure 1. Atmospheric Concentration Trends of SF6 (used in electric power systems, magnesium 

production, and electronics manufacturing) and NF3 (mainly used in electronics manufacturing). Sources: 

(IPCC, 2007), (Arnold et. al. 2012), Advanced Global Atmospheric Gases Experiment (AGAGE) data 

http://agage.eas.gatech.edu/data.htm, and United States Geologic Survey data 

http://water.usgs.gov/lab/software/air_curve/ 

F-GHGs may be emitted from their use in industrial applications, as byproducts of 

production processes, or from their use as substitutes for ozone-depleting substances. 

This paper focuses on the first two sources of emissions. 

The U.S. Environmental Protection Agency (EPA) addresses emissions of F-GHGs 

through a combination of both voluntary and regulatory activities. A number of industrial 

emitters of F-GHGs have partnered with EPA since the 1990s to voluntarily report and 

reduce F-GHG emissions from their operations. EPA works closely with participating 

industries, tracking industry-wide emission trends, benchmarking facility emission 

factors,2 providing technical information, and helping participants (Partners) overcome 

barriers to making process improvements that reduce emissions. Voluntary approaches 

have significantly reduced F-GHG emissions from several industries, and it is expected 

that emissions of PFCs and SF6, in particular, will continue to decline as a result of 

voluntary action (U.S. State Department 2014). As discussed further below, reports from 

Partners have provided key information on long-term trends in emissions and emission 

factors from participating industries. 

In 2011 and 2012, large industrial users and emitters of F-GHGs began reporting

emissions, among other data, to EPA under the Greenhouse Gas Reporting Program 

(GHGRP) (74 FR 56260).3 This national program was established by regulation to 

 2 Emission factor or emission rate refers to the emissions per unit of activity, such as the kilograms of 

PFCs emitted per tonne of aluminum produced.

3 Aluminum and HCFC-22 production facilities began reporting emissions in 2011, submitting estimates of 

their 2010 emissions in that year. Facilities producing electronics, fluorinated gases, magnesium, and 

electrical equipment, and users of electrical equipment, began reporting emissions in 2012, submitting 

5

5.5

6

6.5

7

7.5

8

2000 2002 2004 2006 2008 2010 2012

Concentratoins [ppt]

SF6 Concentrations [AGAGE]

SF6 Concentrations (USGS)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

2000 2002 2004 2006 2008 2010 2012

Concentratoins [ppt]

NF3 Concentrations

[Arnold et. Al]
4

collect accurate, facility-level GHG data to inform policy decisions and the public. The 

GHGRP requires annual reporting by facilities that meet or exceed thresholds that are 

equivalent to emissions of 25,000 metric tons of CO2e per year. 

The facilities required to report emissions of F-GHGs fall into seven source categories. 

These source categories, as well as the F-GHGs emitted and emitting activity, are 

provided in Table 1.

Table 1. Summary of EPA Categories of F-GHG Emitters Subject to the GHGRP

Sourcea F-GHGs Emitted Emitting Activity

Aluminum Production 

(Subpart F)

PFCs Emitted as a by-product of process 

disturbances (anode effects)

Electronics Manufacturing 

(Subpart I)

HFCs, PFCs, SF6, NF3, 

others

Etchant and chamber and wafer cleaning 

gas

Magnesium Production and 

Processing (Subpart T)

HFCs, SF6 Cover gas in magnesium production and 

casting to prevent metal oxidation

Use of Electric Transmission 

and Distribution (ET&D) 

Equipment (Subpart DD)b

SF6 Insulator/arc quenching medium in the 

transmission and distribution of electricity

Manufacture of Electric 

Transmission and Distribution 

Equipment (Subpart SS) b

SF6 Insulator/arc quenching medium in the 

transmission and distribution of electricity

Production of HCFC-22 and 

Destruction of HFC-23 

(Subpart O)

HFC-23 Emitted as by-product of HCFC-22 

production

Production of Fluorinated 

Gases (Subpart L)

HFCs, PFCs, SF6, NF3, 

others

Emitted as reactants, products, or byproducts of production of fluorinated 

gases other than HCFC-22 a

40 CFR Part 98 designates subparts to categories of GHG emitters and suppliers.

b GHGRP data indicates that a minimal amount of PFCs are used for manufacture of ET&D equipment. 

PFCs may be used in ET&D equipment, but emissions data reported under Subpart DD does not indicate 

that PFCs are being used in the United States. 

For most of the source categories in Table 1(with the exception of the Manufacture of 

Electric Transmission and Distribution Equipment), a significant share of reporters have 

ample experience in estimating, reporting, and reducing F-GHG emissions through

EPA’s High Global Warming Potential (High-GWP) Gases Voluntary Programs,

including the:

• Voluntary Aluminum Industrial Partnership (1995-ongoing);

4

• HFC-23 Emission Reduction Agreement (1995-2010);

• SF6 Emission Reduction Partnership for the Magnesium Industry (1999-2010);

5

• PFC Reduction/Climate Partnership for the Semiconductor Industry (1994-2010); 

and6

 

estimates of their 2011 emissions in that year. A total of 41 source categories emitting CO2, methane, 

nitrous oxide, and fluorinated GHGs report under this regulation. 4 http://www.epa.gov/aluminum-pfc/basic.html 5 http://www.epa.gov/highgwp/magnesium-sf6/basic.html
5

• SF6 Emissions Reduction Partnership for Electric Power Systems (1999-

ongoing).

7

When considered together, both voluntary and mandatory reports regarding F-GHG 

emissions provide insights into emitting activities and mitigation efforts in the United 

States at the national and industry level. This paper presents the trends observed in 

GHGRP reported F-GHG emissions, and investigates and discusses potential reasons 

for the observed patterns, including the trends observed among EPA Partners and large 

emitters. The paper is organized into the following sections:

 Section 2 describes the methodology used to look at trends in F-GHG emissions. 

 Section 3 presents the results of the analysis and provides a discussion on the 

observed trends and patterns. 

 Section 4 summarizes the conclusions drawn from the analysis.

2. Methodology

This section describes the data sources and methodology used to analyze trends in 

U.S. F-GHG emissions. The section is broken into two sub-sections. Section 2.1 

describes the data sources including the scope of the analysis; and Section 2.2 

describes the trends analyzed.

2.1 Data Sources

This paper relies on non-confidential emissions data from the EPA GHGRP in addition 

to data from EPA voluntary emission reduction programs, which is used to compare the 

trends observed under the GHGRP to those under the voluntary programs. 

From the mid-1990s through the establishment of the GHGRP, companies that were 

part of EPA’s High GWP Voluntary Programs and Partnerships reported F-GHG 

emissions data to EPA either directly or through third parties. This data has been and 

continues to be used in many EPA and U.S. analyses, such as the Inventory of U.S. 

Greenhouse Gas Emissions and Sinks (EPA 2014a) and the U.S. Climate Action Report

(U.S. State Department 2014). 

Since 2011, EPA has been collecting F-GHG emissions data mainly through the 

GHGRP as opposed to relying on voluntarily reported data. Emissions data from the 

EPA GHGRP are published by the U.S. EPA and provided for public use in multiple 

forms. These forms include; 1) summary files of GHGRP data, by year, on the GHGRP 

website,

8 2) FLIGHT, a GHGRP data visualization tool,9 and 3) the EPA Envirofacts 

 6 http://www.epa.gov/highgwp/semiconductor-pfc/index.html 7 http://www.epa.gov/highgwp/electricpower-sf6/index.html

8 http://www.epa.gov/climate/ghgreporting/ghgdata/reportingdatasets.html

9 http://ghgdata.epa.gov/ghgp/main.do
6

Database, a publically available database that is accessible online.

10 These data 

sources contain non-confidential environmental data reported to EPA through the 

GHGRP (Envirofacts also includes data from other EPA regulatory programs). GHG 

data from these sources is represented in either metric tons of GHG, or metric tons of 

carbon dioxide equivalents (CO2e).11 EPA applies the Intergovernmental Panel on 

Climate Change (IPCC) Fourth Assessment Report GWP values to convert the reported 

emissions data into a common unit of mtCO2e.12

Scope of the Analysis

The GHGRP is a threshold based reporting program. Therefore, the trends analyzed 

and discussed in this paper do not fully represent the entirety of U.S. F-GHG emissions

from industrial sources. Table 2 below indicates the percentage of the GHG emissions 

from each source category that are accounted for by facilities covered by the GHGRP. 

Table 2. Percentage of GHG Emissions Accounted for by Facilities Covered by GHGRP

By Source Category

Source

Estimated Percentage of 

GHGRP GHG Emissions 

Coveragea

Aluminum Production 100 %

Electronics Manufacturing 75-90%

Magnesium Production and Processing 76-77%

Use of Electric Transmission and Distribution (ET&D) Equipment 67%

Manufacture of Electric Transmission and Distribution (ET&D) 

Equipment

66%

HCFC-22 Production and HFC-23 Destruction 100%

Production of Fluorinated Gases 100%

Source: EPA, 2014b a Coverage estimates include both F-GHGs and other GHGs emitted from these sources.

To avoid introducing trends caused by changes in the set of facilities reporting in any 

given year, this analysis focuses on facilities that have reported their emissions to the

GHGRP for all of the years from 2011 through 2013 and whose emissions have been 

verified. These facilities represented between 85 and 100 percent of GHGRP-reported

emissions for their source categories, depending on the year and the industry.

 10 http://www.epa.gov/envirofw/ 11 GHG data is reported to the U.S. EPA in metric tons of GHG; EPA then converts this to CO2e using 

consistent GWPs. The sole exception is the data received from fluorinated gas producers, as discussed 

below.

12 The analysis relies on global warming potential values from Table A-1 of Subpart A of 40 CFR Part 98.

http://www.ecfr.gov/cgi-bin/textidx?SID=af924f3ef4d2068f574eb6c4c102364a&node=ap40.21.98_19.1&rgn=div9 These are reflective of 

the GWPs published in the IPCC Fourth Assessment Report (IPCC, 2007)
7

2.2 Trends Analyzed

The granularity of emissions data provided by the GHGRP enables U.S. F-GHG 

emissions data to be grouped and analyzed in several ways. This paper investigates the 

groupings/trends as presented in Table 3.

Table 3. Analysis Groupings of GHGRP F-GHG Data

Trend Gas Type Source PFCs HFCs SF6 NF3 All F-GHGs Aluminum Production Electronics Manufacturing Magnesium Production Use of ETD Equipment Equipment

Manufacture of ETD All Five 

F-GHG Emitting 

Source Categories

Aggregate of F-GHGs and All Sources X X

Aggregate of F-GHGs for Each Source X X X X X X

Each F-GHG for All Sources X X X X X

Each F-GHG for Each Industry X X X X X X X X X

In order to further analyze the overall 

trends of the source categories shown in 

Table 3, trends for large emitters and 

trends for GHGRP reporters that 

are/were Voluntary Program Partners 

with EPA are investigated. EPA 

Voluntary Program Partner companies

may or may not be required to report

facility-level emissions under the 

GHGRP, depending on whether the 

facility-level reporting threshold is met.

3. Results and Discussion

EPA High GWP Gases Voluntary Program Partnerships have a long track record of 

success; from the inception of these Partnerships, U.S. F-GHG emissions reported by 

EPA Partners have fallen significantly. While the GHGRP is a reporting program and 

does not require mitigation of GHGs, the results of this analysis reveal that F-GHG 

emissions reported through the GHGRP are also decreasing. This section investigates 

the trends in reported emissions and discusses potential reasons for why this decrease

is occurring.

Partners GHGRP 

Reporters

Figure 2. Overlap of EPA High 

Gases Voluntary Program Partners 

and EPA GHGRP Reporters
8

This section is broken into two sub-sections. Section 3.1 presents overall trends in 

reported F-GHG emissions, and focuses on these trends with respect to the various 

types of F-GHGs and sources. Second, Section 3.2 discusses the contributions of 

various types of reporters to GHGRP-reported F-GHG emission trends. The types of

reporters include EPA Voluntary Program Partners/Non-Partners and the larger/largest 

emitters.

13

Although the emission trends for HCFC-22 Production and Production of Fluorinated 

Gases are discussed briefly in section 3.2 below, these trends are generally not 

included in the discussion because they are driven by external factors. Specifically, the 

emission trend for HCFC-22 production is affected by the phaseout of the production 

HCFC-22 for non-feedstock uses under the Clean Air Act and Montreal Protocol, while 

the emission trend for fluorinated gas production is affected by the use of different 

GWPs in 2013 than in 2011 and 2012.14 

3.1 GHGRP F-GHG Trends (2011-2013)

Figure 3 below shows the trends from all F-GHG-emitting source categories other than 

HCFC-22 and fluorinated gas production for 2011 through 2013.

 13 For purposes of this paper, larger is defined as above 50,000 mtCO2e and largest 100,000 mtCO2e.

14 This inconsistency in GWPs is expected to be removed in the near future. To date, fluorinated gas 

producers have reported their emissions only in terms of CO2e under temporary reporting provisions. 

Under a rule proposed in November, 2013, fluorinated gas producers would report emissions of individual 

chemicals that exceeded 1,000 mtCO2e in tons of that chemical for 2011 and later years, and would 

report other emissions in CO2e using a single set of GWPs.
9

Figure 3. Trends in U.S. GHGRP F-GHG Emissions (Note: This chart only represents HFC 

emissions from magnesium production, and does not include HFC emissions from HCFC-22 

Production/HFC-23 Destruction or F-GHG Production, which are on the magnitude of millions of 

metric tons CO2e per year.)

The trends indicated in Figure 3 for the various types of F-GHGs can be attributed to 

reductions (or increases) seen for specific sectors. Source-specific F-GHG trends are 

displayed in Figure 4.

Figure 4. Trends in F-GHG Emissions, by Source Category

Between 2011 and 2013, U.S. GHGRP F-GHG emissions from these five source 

categories decreased by 19 percent (2.5 MMTCO2e), with a more noticeable drop in 

emissions between 2011 and 2012 than between 2012 and 2013. Reductions in annual 

emissions are observed for all types of F-GHGs, with the exception of HFCs (emitted 

from magnesium and electronics production), which actually increased by 14 percent 

(0.03 MMTCO2e). The largest reduction in annual emissions between 2011 and 2013 is 

seen for SF6 (24 percent, 1.4 MMTCO2e), followed by PFCs (16 percent, 1.1

MMTCO2e), then NF3 (17 percent, 0.1 MMTCO2e).

A closer examination of these trends, including consideration of underlying activity 

levels and emission factors, follows.
10

F-GHG Specific Trends

SF6 Trends: Reductions in annual SF6 emissions are driven mainly by reductions in 

emissions from the use of electrical transmission and distribution (ET&D) equipment 

and magnesium production. These reductions have occurred despite increased activity 

levels in both of these source categories.

Electrical equipment use, the largest source of SF6 emissions in the United States, saw 

SF6 emissions decrease by 25 percent from 2011 to 2013 (0.9 MMTCO2e, more than

half of the SF6 reductions). This reduction was driven by a 33-percent reduction in the 

emission factor for this source category (SF6 emissions per unit of installed nameplate 

capacity), which declined from 3.4 percent in 2011 to 2.6 percent in 2012 and then 2.3

percent in 2013. (See Table 8 below for a more detailed analysis of these reductions.) 

This indicates that the absolute reductions in SF6 emissions are a result of emission 

mitigation measures.

The drop in emissions and in the emissions factor from the use of ET&D equipment is a 

continuation of a trend observed through EPA’s SF6 Emission Reduction Partnership for 

Electric Power Systems. Partners comprise approximately 75 percent of the ET&D 

facilities required to report to the GHGRP, and they comprise 65 percent of the 

nameplate capacity of ET&D reporters.

15 However, while the trend in emission 

reductions is continuing for Partners, much of the reduction seen in GHGRP data is 

coming from utilities that are not participants in the EPA Voluntary Program Partnership. 

Non-Partners account for 45 percent of emission reductions (0.41 MMTCO2e) although 

they represent 35 percent of GHGRP reporter nameplate capacity. As discussed further 

in section 3.2, non-Partners may be making relatively large reductions as they take

advantage of relatively large and/or inexpensive emission reduction opportunities (i.e., 

“low hanging fruit,” such as replacing major leaking circuit breakers) that Partners have 

already taken advantage of under the voluntary programs.

Manufacturing of electrical equipment is a smaller source of SF6 but contributed 

significantly to the observed decrease in SF6 emissions, with emissions falling by 0.15 

MMTCO2e between 2011 and 2013. This corresponds to a decrease in the industrywide emission factor (SF6 emission/quantity of SF6 delivered in new equipment) from 20 

percent in 2011 to eight percent in 2013, again indicating that facilities are taking

actions to reduce and manage emissions.

Sulfur hexafluoride emissions from magnesium production and processing fell by 24

percent (or 0.31 MMTCO2e) from 2011 to 2013. This decline occurred despite the fact 

that magnesium production and processing levels in the U.S. for GHGRP reporters 

 15Based on 2013 beginning-of-the year-nameplate capacity.
11

have increased since 2011 as the industry has recovered from the recession and 

automotive parts have relied increasingly on lighter metals, such as magnesium, as 

opposed to steel.16 GHGRP data indicates that the industry is shifting from using SF6 as 

a cover gas to HFC-134a (as well as other low GWP cover gases such as FK5-1-12) 

because of environmental concerns related to SF6 as an extremely potent GHG as well 

as potential other factors such as price (Ricketts et. al.).

PFC Trends: Figure 3 indicates an overall decrease of annual PFC emissions from 

2011 to 2013. These reductions are mainly being driven by reductions from electronics 

manufacturing (0.56 MMTCO2e, an 18 percent decline), and aluminum production (0.50

MMTCO2e, a 14 percent decline). The decreases appear to result partly, but not 

completely, from reductions in activity.

In regards to electronics manufacturing, the annual production, in terms of produced 

substrate area, reported to the GHGRP decreased from 2011 to 2013. Activity for 

electronics manufacturing may also be tracked using an indicator referred to as total 

manufactured layer area (TMLA). TMLA is the product of the number of layers that 

comprise different kinds of semiconductors devices, including both silicon wafer and 

metal interconnect layers, and silicon consumption (i.e., the area of semiconductors 

produced). As technologies progress and chips need to become faster and smaller, the 

number of layers increases. TMLA may be a better indicator of F-GHG emissions 

because as the number of layers increase, the number of F-GHG using process steps 

also increases. According to data reviewed from the International Semiconductor 

Technology Roadmap (ITRS),17 the number of layers for different technology types and 

nodes has remained consistent between 2011 and 2013. Therefore, one can assume 

that the TMLA trend would align with the trend of decreasing produced area of substrate 

from 2011 to 2013 for GHGRP reporters. These activity reductions align with reductions 

in electronics manufacturing PFC emissions. Therefore, some of the reductions may be 

a result of decreasing activity. Additionally, recent testing and research indicate better 

practices for abatement system maintenance and operation are being employed, 

leading to reductions in F-GHG emissions from electronics manufacturing (Davia et. al. 

2013). However, this appears not to have had as large of an impact as the trend in 

activity.

Table 4 shows the trends in primary aluminum production, emissions, and emission 

factors between 2011 and 2013.

 16 Due to limitations on use of confidential business information collected through the EPA GHGRP, it is 

not possible to publish production data for magnesium production. While the United States Geologic 

Survey publishes a subset of magnesium production data in its Minerals Yearbook (it does not publish 

primary production information), this data may not correspond to the same population of companies that 

are reporting through the GHGRP.

17 http://www.itrs.net/
12

Table 4. Trends in U.S. Aluminum Production, Emissions, and Emission Factors (2011-2013)

2011 2012 2013

Production (ktonnes) 18 1,986 2,070 1,948

GHGRP Emissions (MMTCO2e) 3.5 2.9 3.0

Emission Factor (tCO2e/tonne Al) 1.7 1.4 1.5

As shown in Table 4, PFC emissions from aluminum production declined significantly 

between 2011 and 2012, driven by a significant decrease in the average emission 

factor. However, the emission factor in 2011 was unusually large for recent years, as 

can be seen in Figure 6, below, which includes data reported by EPA Partners in the 

two decades before 2011. (This data reflects reports from all but one U.S. aluminum 

production facility.) The increase in 2011 was due to atypically large emissions for at 

least one aluminum facility during production start-up. Both emissions and the emission 

factor increased slightly between 2012 and 2013. Therefore, it does not appear that the 

reductions between 2011 and 2013 are being driven by long-term changes in GHG 

management practices. However, as shown by Figure 6 and as discussed further 

below, most primary aluminum producers had already instituted GHG management 

practices and achieved significant emission reductions before they began to report 

under the GHGRP. 

NF3 Trends: NF3 is used in electronics manufacturing to clean chemical vapor 

deposition chambers. Emissions resulting from the use of NF3 have decreased from 

2011 to 2013. This is due to the same trends driving PFC emissions from electronics 

manufacturing, described above.

HFC Trends: HFCs are the only type of F-GHGs from the five source categories 

studied here for which annual emissions are increasing. However, because HFCs make 

up only two percent of the emissions from these source categories, the reductions of the 

other types of F-GHGs dominate the trend. HFCs are used in electronics manufacturing 

and magnesium production. HFCs emissions actually decreased between 2011 and 

2013 for electronics manufacturing (20 percent, 0.04 MMTCO2e). However, this was

counterbalanced by an increase in HFC emissions from magnesium production 

(increase of 443 percent, or 0.07 MMTCO2e). This is a result of switching from the use 

of SF6 cover gas to HFC-134a cover gas by one large producer in 2013. While this 

transition increased HFC emissions from magnesium production, it is important to note 

that it decreased overall fluorinated GHG emissions in CO2e, because the GWP of 

HFC-134a is one sixteenth that of SF6. 

It is also important to note that the HFC emissions from electronics and magnesium 

production are a small fraction of the HFC emissions from the three major sources of 

 18 Aluminum production data is provided by the United States Geologic Survey Minerals Yearbook 

(http://minerals.usgs.gov/minerals/pubs/commodity/aluminum/index.html#myb)
13

HFCs, which include HCFC-22 production, other fluorinated gas production, and, most 

important, substitution for ozone-depleting substances. HFCs are replacing ozonedepleting substances as refrigerants, aerosol propellants, solvents, and fire 

retardants.

19 These uses of HFCs are covered by other regulatory programs, and hence 

are not analyzed as part of this paper.20

Emissions from Producers of HCFC-22 and Other Fluorinated Gases

Figure 5 shows the emission trends for producers of HCFC-22 and other fluorinated 

gases.

Figure 5. Trends in F-GHG Emissions from HCFC-22 and Other Fluorinated Gas Production

As discussed above, these trends are affected by factors other than emission factors 

per unit of activity. Specifically, the upward trend observed in emissions from 

fluorinated gas production is likely to be at least partially attributable to the GHGRP’s 

adoption of AR4 GWPs in 2013, which for F-GHGs are 18 percent higher, on average, 

than the SAR GWPs used previously for reporting. The downward trend in emissions 

from HCFC-22 production is at least partially attributable to the phaseout of HCFC-22 

production for non-feedstock uses that is occurring under the Clean Air Act and 

Montreal Protocol.

3.2 Observed Trends for Various Types of GHGRP Reporters

Previous analyses performed on GHGRP data (e.g., to include this data in the Inventory

of U.S. Greenhouse Gas Emissions and Sinks) have indicated that the F-GHG emission

 19 http://www.epa.gov/climatechange/ghgemissions/gases/fgases.html 20 http://www.epa.gov/ozone/title6/index.html
14

patterns of facilities differ based on: (1) participation in EPA’s High-GWP Gases 

Voluntary Program Partnerships, and (2) the magnitude of the total F-GHG emissions

reported by the facility. We therefore examined these two characteristics and their 

impacts on emissions and emission factors in this study. This examination showed 

larger percentage reductions for reporters that did not participate in the EPA 

Partnerships and for reporters with relatively high magnitudes of reported emissions. 

While EPA Partners account for the majority of reported F-GHG emissions (between 67 

percent and 71 percent), these reporters are not necessarily also the same set of 

reporters that are the larger and largest emitters.

Table 5. Trends in F-GHG Emissions Reported by Larger Emitters (2011-2013), 

50,000 mtCO2e threshold

Reporter Type

F-GHG Emissions

(MMTCO2e)

2011–2013 

Reduction

(MMTCO2e)

Percent Reduction

2011 2012 2013

Total GHGRP Reporters

(5 source categories) 13.1 11.3 10.6 2.5 19%

Larger (based on 2011 data) 11.0 8.1 7.5 3.5 32%

Larger (based on 2013 data) 9.9 7.8 7.6 2.3 24%

Table 6. Trends in F-GHG Emissions Reported by Largest Emitters (2011-2013), 

100,000 mtCO2e threshold

Reporter Type

F-GHG Emissions 

(MMTCO2e)

2011–2013 

Reduction

(MMTCO2e)

Percent Reduction

2011 2012 2013

Total GHGRP Reporters

(5 source categories) 13.1 11.3 10.6 2.5 19%

Largest (based on 2011 data) 9.0 7.2 6.7 2.3 25%

Largest (based on 2013 data) 7.8 6.8 6.4 1.4 18%

Tables 5 and 6 show the trends for the “larger” and “largest” emitters, where thresholds 

for defining these categories are 50,000 mtCO2e and 100,000 mtCO2e respectively. 

These thresholds are applied for both the reporting years 2011 and 2013.21 The data 

indicate that the reductions, in percentage terms, of the “larger” and “largest” emitters in 

2011 are higher than the average reductions of all reporters. This pattern persists for 

the “larger” reporters in 2013, although it does not persist for the “largest” reporters in 

2013, whose average reductions are one percentage point lower than the average for

all GHGRP reporters.

 21 By definition, facilities with downwardly trending emissions have larger emissions in earlier years than 

in later years, and facilities with upwardly trending emissions have larger emissions in later years than in 

earlier years. Thus, studying the facilities with the largest emissions in 2011 may over-represent facilities 

with downwardly trending emissions, while studying the facilities with the largest emissions in 2013 may 

over-represent facilities with upwardly trending emissions. For this reason, we studied both sets here.
15

Table 7. Trends in F-GHG Emissions Reported under the GHGRP by

EPA Voluntary Program Partners and Non-Partners

(2011-2013)

Reporter Type

F-GHG Emissions 

(MMTCO2e)

2011–2013 

Reduction

(MMTCO2e)

Percent Reduction

2011 2012 2013

Total GHGRP Reporters

(4 source categories with 

Partnerships)

12.8 11.1 10.4 2.3 18%

Partners 8.7 7.7 7.5 1.2 14%

Non-Partners 4.1 3.4 3.0 1.1 27%

Table 7 presents the trends in F-GHG emissions reported under the GHGRP by EPA 

Voluntary Program Partners and Non-Partners for 2011 through 2013. The results in 

this table indicate that Non-Partners are contributing nearly as much to total reductions 

as Partners, although they account for less than half of the emissions and activity in 

each of the four source categories with Partnerships. The percentage by which the 

Non-Partners reduced emissions between 2011 and 2013 is almost twice as large as 

the percentage by which the Partners reduced emissions. 

For one source category, use of ET&D equipment, activity data are publicly available, 

allowing a closer examination of emission factors among facilities that are Partners, 

non-Partners, “larger,” and “largest.” This examination sheds light on a possible reason 

for the patterns observed above. Table 8 shows the emission factors of the various 

types of ET&D reporters from 2011 through 2013.

Table 8. Trends in Emission Factors for Users of ET&D Equipment

(2011-2013)

Reporter Type SF6 Emission Factor (kg 

Emissions/kg Nameplate 

Capacity) 

2011-2013 

Reduction in 

Emission 

Factor

(kg/kg)

Percent 

Reduction in 

Emission 

Factor

2011 2012 2013

Total GHGRP ET&D Reporters

 

0.034 

 

0.026 

 

0.023 

 

0.011 33%

EPA Partners

 

0.029 

 

0.023 

 

0.020 

 

0.009 32%

Non-Partners

 

0.043 

 

0.031 

 

0.028 

 

0.015 35%

Larger (based on 2011 data)

 

0.047 

 

0.032 

 

0.028 

 

0.019 41%

Largest (based on 2011 data)

 

0.059 

 

0.038 

 

0.032 

 

0.027 46%
16

In general, Table 8 shows that the facilities with the largest average emission factors in 

2011 made the largest reductions in their emission factors between 2011 and 2013. 

This is an expected result. Facilities that have already attained relatively low emission 

factors are likely to have fewer options remaining to them to make further reductions 

than facilities that have relatively high emission factors. For example, EPA Partners 

have been conducting emissions mitigation activities throughout the lifetime of the 

Partnerships. Thus, they are likely to have already taken advantage of the options with 

the largest and least expensive reductions. Nevertheless, as shown in Table 8, Partners 

have continued to reduce their average emission factor. In addition to ongoing efforts to 

replace leaking equipment, Partner companies are working to further their emission 

reductions by advancing their mitigation strategies—for example, examining their 

system for all possible sources—large and small--of emissions; purchasing new laser 

leak detection cameras; working with their vendors to receive SF6 inventory related 

reports; tightening gas cylinder inventories; and operating more recycling carts (EPA 

2014d). 

Comparison of GHGRP Trends to the Trends Reported Under the Partnerships

Figure 6, below, plots data on emission rates from three partnerships,22 normalized to 

the start year of each program. 

Figure 6. Emission Rates of Partner Companies Compared to Base Year

Several conclusions can be drawn from the figure.

 22 The emission factors for electric power systems and semiconductors are based on the Partners’ 

reported nameplate capacity and estimated TMLA, respectively. The emission factor for aluminum is 

based on industry-wide emissions and production, which are similar to the emissions and production 

reported by the Partners. (Only one aluminum facility was not a Partner.) 

0.00

0.20

0.40

0.60

0.80

1.00

1.20

19901991199219931994199519961997199819992000200120022003200420052006200720082009201020112012

Aluminum Electric Power Systems Semiconductors
17

• First, as noted above, the reductions in emission factors made by Partners over 

the last two decades have been deep and lasting, exceeding 75 percent for all 

three industries. 

• Second, three years into the voluntary program for each industry, the point 

comparable to 2013 for the GHGRP (the third year of reporting), the emission 

factors for electric power systems and aluminum had declined by 13 and 22 

percent, respectively. (The estimated emission factor for semiconductors did not 

begin to decline until emission reduction options, such as the replacement of 

C2F6 with NF3 for chamber cleaning, began penetrating the market, but at that 

point the emission factor fell sharply.) The comparable reductions in the 

emission factors for electric power systems and aluminum under the GHGRP 

are 33 percent and 13 percent, respectively. 

• For electric power systems, the percentage reduction in the emission factor 

was higher three years into the GHGRP than three years into the voluntary 

program. However, because the 1999 emission factor was nearly four times 

as large as the 2011 emission factor, the absolute reduction in the emission 

factor was higher three years into the voluntary program than three years into 

the GHGRP. Interestingly, after slowing in 2009 and 2010, the reductions 

achieved by electric power system Partners have accelerated since the 

GHGRP became effective. It is possible that this trend is attributable to the 

fact that the GHGRP, as a mandatory and economy-wide reporting program, 

has more visibility and weight than the reporting done through EPA’s 

Voluntary Programs. However, as discussed below, this trend is not observed 

for aluminum and semiconductor production.

• As noted above, the decrease in the emission factor for aluminum under the 

GHGRP is an artifact of an unusually high emission factor in 2011. In general, 

for aluminum and semiconductor production, the percent reductions as well 

as absolute reductions in emission factors appear to have leveled off in recent 

years. For these two source categories, the reductions achieved under the 

GHGRP by the Partners appear to be smaller than those achieved earlier 

under the Partnerships, perhaps limited by the availability of low-cost 

emission reduction options. 

Possible Explanations for the Trends

More accurate or improved data collection practices. An alternative explanation for 

the trends discussed above is that they are introduced by improvements in data 

collection and emissions estimation that occur over time. In the first year of data 
18

collection under the GHGRP, reporters had the option to rely on alternative monitoring 

methods (known as “Best Available Monitoring Methods” or BAMM) if the newly covered 

facility was unable to acquire, install, and operate the required monitoring equipment. 

This provision was permitted to facilities for a limited amount of time, recognizing that 

adjustments to respond to the new regulation may require additional time in order to 

minimize impacts to normal business operations (EPA, 2014c). For the first year or 

reporting in 2011, 26 percent of reporters used BAMM. This percentage dropped to zero 

in 2012 and 2013.23 As a result, the first year of reported emissions may include 

estimates that do not all meet the accuracy requirements set forth under the GHGRP.

Additionally, reporters have become more familiar with their data and the required 

emissions monitoring and calculation practices since 2011. GHGRP reporters that were 

not EPA Voluntary Program Partners did not have institutional knowledge of emission 

estimation practices at the outset of the GHGRP.

24 As noted above, about half of overall 

F-GHG reductions (1.27 MMTCO2e) from 2011-2013 are attributed to GHGRP reporters 

that were not part of the EPA’s High GWP Gases Voluntary Program Partnerships. 

In general, errors in estimating emissions are expected to have been equally likely to 

result in over- or underestimates in 2011, making it unlikely that such errors are a 

significant driver of the observed emission trends. One possible exception to this is the 

trend for electric transmission and distribution equipment. One of the issues that has 

arisen during the implementation of the GHGRP for this source category is that 

overcharging of new equipment is common, and such overcharging results in an 

overestimate of emissions. (This is because new equipment is being charged with a 

quantity of SF6 that is greater than its nameplate capacity, and the emission estimation 

method for this source category relies on the assumption that the quantity charged 

equals its nameplate capacity). As facilities learn that overcharging results in an 

overestimate of emissions, they may be overcharging less frequently, resulting in an 

apparent (but not a real) reduction in emissions. However, by itself, this is not expected 

to have resulted in reductions of the magnitude observed. 

Increased reporter awareness of facility emissions. Once it is concluded that the 

observed decreases in emissions and emission factors are real, the question becomes 

what is driving them. One possibility is increased reporter awareness of facility 

emissions. In some cases, facilities that have not previously tracked emissions may not 

have been aware of their magnitude until they began tracking and reporting the 

 23 This includes facilities that report emissions from production of electronics, fluorinated gases, 

magnesium, and electrical equipment, as well as from use of electrical equipment. . 24 Subparts F, T, and DD (Aluminum Production, Magnesium Production, and Use of ET&D) of the EPA 

GHGRP relies upon the same emission estimation method Partners used to estimate and report 

emissions as part of the EPA Voluntary Program. Subpart I (Electronics Manufacturing) relies on similar 

methods as used by some EPA Partners.
19

emissions under the GHGRP. Once facilities are alerted to their emissions, they may 

take action to control them due to concerns regarding public reaction (discussed further 

below), cost control (particularly when the emitted chemical is a valuable commodity), or 

a desire to be good stewards of the environment. As discussed above, tracking of 

emissions has been an important part of EPA’s voluntary emission reduction 

partnership programs for these reasons.

Increased public awareness of facility emissions. As noted above, facilities may 

also reduce emissions because they are concerned about possible public reaction to 

them. The GHGRP is a recently established yet well-publicized national program that, 

among other purposes, provides the public with access to GHG emissions information. 

Programs that provide facility-level emissions information to the public (so called “Rightto-Know” laws) may incentivize companies to reduce those emissions (Mastromonaco 

2013; Konar and Cohen 1997). The Emergency Planning and Community Right to 

Know Act (EPCRA) is a classic example of a “Right-to-Know” law in the United States. 

Under this law, EPA created the Toxic Release Inventory (TRI), a program that requires 

firms to annually report information on their emissions of a variety of pollutants, which is 

then made available to the public. Since the inception of the TRI, emissions of the 

pollutants covered by this program have decreased, for example in the last decade by 

approximately 30 percent. Studies have drawn different conclusions regarding whether 

public pressure has influenced these reductions (Mastromonaco 2013; Konar and 

Cohen 1997). Nonetheless, in today’s world of corporate social responsibility, 

shareholders and other stakeholders view environmental issues, such as climate 

change, as being within the scope of a company’s responsibilities; they are demanding 

greater transparency on the social and environmental impact of a company’s activities 

(Noked 2013). Public pressure may be a reason for reduced annual F-GHG emissions 

in the United States. By making a concerted effort to reduce emissions (e.g., through 

process optimization, improved gas management, or end-of-pipe controls), facilities can 

contribute to improvements in their corporate reputation.

4. Conclusions

The SF6, PFC, and NF3 emissions reported to the GHGRP from production of 

aluminum, semiconductors, magnesium, and electrical equipment, as well as from use 

of electrical equipment, have decreased since 2011, whereas the reported (much 

smaller) HFC emissions from these source categories have increased over the same

time period. The overall decrease in emissions appears to be attributable to reductions 

in emission factors in some cases and reductions in activity levels in others. 

Further examination of the root causes of the decrease in F-GHG emissions reveals 

that 1) the largest reductions can be attributed to very large emitters, and 2) NonPartners contribute more to emission reductions than would be expected based on their 
20

activity levels and emissions. For electric power systems, these patterns are clearly 

related to the relatively high emission factors for very large emitters and for NonPartners in 2011; these high emission factors imply that very large emitters and NonPartners had not implemented emission reduction options to the extent that smaller 

emitters and Partners had in that year. In general, the apparent widespread use of 

emission reduction options since 2011 may be attributable to increased reporter and 

public awareness of facility GHG emissions. Furthermore, facilities may be able to 

manage their systems more effectively now that they are required to report on process 

inputs and resulting emissions, a concept often expressed by the adage, “What gets 

measured gets managed.”

This analysis of early-reported GHGRP F-GHG emissions data is telling. However, as 

the GHGRP continues, including additional years of data will help to validate the 

conclusions drawn about the early-reported F-GHG emission trends in this paper. The 

trends observed to date should be revisited after another few years of data are collected 

to see whether these patterns continue or change. Additionally, in light of the rise in 

atmospheric concentrations of F-GHGs (Figure 1), it will be important to reexamine 

reporting trends to see whether reductions in reported U.S. F-GHG emissions continue 

to be observed and to investigate any inconsistencies between the emission trends

reported for the U.S. and other countries versus atmospheric measurements.

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22

Table(s)

Table 1. Summary of EPA Categories of F-GHG Emitters Subject to the GHGRP

Table 2. GHGRP Emissions Coverage for F-GHG Emitting Sources

Table 3. Analysis Groupings of GHGRP F-GHG Data

Table 4. Trends in U.S. Aluminum Production, Emissions, and Emission Factors (2011-

2013) 

Table 5. Trends in Larger Emitter Reported F-GHG Emissions (2011-2013), 50,000 

mtCO2e threshold

Table 6. Trends in Largest Emitter Reported F-GHG Emissions (2011-2013), 100,000 

mtCO2e threshold

Table 7. Trends in EPA Voluntary Program Partner and Non-Partner GHGRP Reported 

F-GHG Emissions (2011-2013)

Table 8. Trends in Emission Factors for Users of ET&D Equipment (2011-2013)
23

Figure Captions

Figure 1. Atmospheric Concentration Trends of SF6 (used in electric power systems, 

magnesium production, and electronics manufacturing) and NF3 (mainly used in 

electronics manufacturing).

Figure 2. Overlap of EPA High Gases Voluntary Program Partners and EPA GHGRP 

Reporters

Figure 3. Trends in U.S. GHGRP F-GHG Emissions

Figure 4. Trends in F-GHG Emissions, by Source Category

Figure 5. Trends in F-GHG Emissions from HCFC-22 and Other Fluorinated Gas 

Production

Figure 6. Emission Rates of Partner Companies Compared to Base Year