TECHNICAL SUPPORT DOCUMENT FOR
INDUSTRIAL GAS SUPPLY: PRODUCTION,
TRANSFORMATION, AND DESTRUCTION OF
FLUORINATED GHGS AND N2O
PROPOSED RULE FOR MANDATORY
REPORTING OF GREENHOUSE GASES
Office of Air and Radiation
U.S. Environmental Protection Agency
February 6, 2009
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Contents
1. Source Description 3
a. Total U.S. Production 3
2. Options for the Scope of Activities Reported 5
3. Options for Reporting Threshold 6
4. Monitoring Methods and Current Plant Practices 8
a. Production 8
b. Destruction 9
c. Equations 12
d. Relationship of proposed requirements to current plant practices 13
5. Procedures for Estimating Missing Data 14
6. QA/QC Requirements 15
7. Reporting Procedures 15
8. Recordkeeping Procedures 16
9. References 17
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1. Source Description
Fluorinated greenhouse gases (fluorinated GHGs) are man-made gases used in several sectors.
They include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6),
nitrogen trifluoride (NF3), and a number of fluorinated ethers. (Fluorinated GHGs also include
chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), but these ozone-depleting
substances (ODSs) are currently being phased out and otherwise regulated under the Montreal
Protocol and Title VI of the Clean Air Act, and EPA is not proposing requirements for them
under the GHG Reporting rule.) Hydrofluorocarbons (HFCs) are the most commonly used
fluorinated GHGs, used primarily to replace ozone-depleting substances in a number of
applications, including air-conditioning and refrigeration, foams, solvents, and aerosols. PFCs
are used in fire fighting and to manufacture semiconductors and other electronics. Sulfur
hexafluoride (SFe) is used in a diverse array of applications, including electrical transmission and
distribution equipment (as an electrical insulator and arc quencher) and in magnesium casting
operations (as a cover gas to prevent oxidation of molten metal). Nitrogen trifluoride (NF3) is
used in the semiconductor industry, increasingly to reduce overall semiconductor greenhouse gas
emissions through processes such as NF3 remote cleaning and NF3 substitution during in-situ
cleaning. Fluorinated ethers (HFEs and HCFEs) are used as anesthetics (e.g., isofluorane,
desflurane, and sevoflurane) and as heat transfer fluids (e.g., the H-Galdens). The ability of
fluorinated GHGs to trap heat in the atmosphere is often thousands to tens of thousands as great
as that of CO2, on a pound-for-pound basis. Some fluorinated GHGs are also very long lived;
SF6 and the PFCs have lifetimes ranging from 3,200 to 50,000 years (IPCC, 2006).
Once produced, fluorinated GHGs can have hundreds of millions of downstream emission
points. For example, the gases are used in almost all car air-conditioners and household
refrigerators and in other ubiquitous products and applications. Thus, tracking emissions of
these gases from downstream uses would be extremely difficult.
In addition, fluorinated GHGs may also be used as feedstocks to produce other chemicals.
Conversations with chemical manufacturers indicate that there is at least one case in which an
HFC is used as a feedstock, and that use of HFCs as feedstocks is likely to grow. There are
numerous examples of CFCs being used as feedstocks, including the use of CFC-113a to
manufacture HFC-134a and HFC-245fa and the use of CFC-114 to manufacture a series of
vinylidene compounds used in various products and applications. Although CFCs are excluded
from the definition of fluorinated GHG, they are in some ways chemically similar to HFCs.
Nitrous oxide (N2O), a clear, colorless, oxidizing gas with a slightly sweet odor is produced
primarily for use in carrier gases with oxygen to administer more potent inhalation anesthetics
for general anesthesia and as an anesthetic in various dental and veterinary applications. N2O is
a strong greenhouse gas with a global warming potential of 310 (SAR).
The reporting of fluorinated GHG emissions from the production process is addressed in a
separate technical support document (EPA-HQ-OAR-2008-0508-012).
a. Total U.S. Production
In 2006, 23 U.S. facilities produced over 350 million mtCO2e of HFCs, PFCs, SF6, fluorinated
ethers, N2O, and NF3. More specifically, 2006 production of HFCs is estimated to have
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exceeded 250 million mtCC^e while production of PFCs, SFe, fluorinated ethers, N2O, and
is estimated to have been near 150 million mtCC^e. The quantities of HFCs, PFCs, SF6,
fluorinated ethers, N2O, and NF3 transformed and destroyed are currently unknown.
For some of the GHGs listed above, including fluorinated ethers and NF3, the IPCC Second
Assessment Report (SAR) does not provide GWPs. Table 1 presents recent GWPs for several
fluorinated ethers, including H-Galdens and anesthetics such as desflurane (F£FE-236ea2) and
isoflurane (HCFE-235da2).
Table 1. GWPs for Selected GHGs from AR-4, the 2006 Scientific Assessment of Ozone Depletion, and TAR
Name
HFE-125
HFE-134
HFE-143a
HFE-227ea
Isoflurane
HG-10
Desflurane
HFE-236fa
HFE-245cb2
HFE-245fal
HFE-245fa2
HFE-254cb2
HFE-263fb2
HFE-329mcc2
HFE-338mcf2
HG-01
HFE-347mcc3
HFE-347mcf2
HFE-347pcf2
HFE-356mec3
HFE-356pcc3
HFE-356pcf2
HFE-356pcO
HFE-365mcO
HFE-374pc2
N/A
#
125
134
143a
227ea
235da2
236cal2
236ea2
236fa
245cb2
245fal
245fa2
254cb2
263fb2
329mcc2
338mcf2
338pccl3
347mcc3
347mcf2
347pcf2
356mec3
356pcc3
356pcf2
356pcO
365mcO
374pc2
N/A
CAS#
3822-68-2
1691-17-4
421-14-7
2356-62-9
26675-46-7
Not available
57041-67-5
20193-67-3
22410-44-2
Not available
1885-48-9
425-88-7
460-43-5
67490-36-2
156-05-3
Not available
28523-86-6
Not available
406-78-0
382-34-3
Not available
Not available
35042-99-0
512-51-6
13171-18-1
Chemical Formula
CHF2OCF3
CHF2OCHF2
CH3OCF3
CF3CHFOCF3
CHF2OCHC1CF3
CHF2OCF2OCHF2
CHF2OCHFCF3
CF3CH2OCF3
CH3OCF2CF3
CHF2CH2OCF3
CHF2OCH2CF3
CH3OCF2CHF2
CF3CH2OCH3
CF3CF2OCF2CHF2
CF3CF2OCH2CF3
CHF2OCF2CF2OCHF2
CH3OCF2CF2CF3
CF3CF2OCH2CHF2
CHF2CF2OCH2CF3
CH3OCF2CHFCF3
CH3OCF2CF2CHF2
CHF2CH2OCF2CHF2
CHF2OCH2CF2CHF2
CF3CF2CH2OCH3
CH3CH2OCF2CHF2
(CF3)2CHOCH3
Global Warming Potential (100 yr.)
IPCC
Fourth
Assessment
Report
14,900
6,320
756
l,540a
350
2,800
989a
487a
708a
286a
659
359
lla
919a
552a
1,500
575
374a
580
101a
110
265a
502a
lla
557a
27
WMO
Scientific
Assessment
of Ozone
Depletion
14,910
6,320
756
1,540
349
2,820
989
487
708
286
659
359
Not listed
919
552
1,500
575
374
Not listed
101
110
265
502
Not listed
557
Not listed
IPCC Third
Assessment
Report
14,900
6,100
750
1500
340
2,700
960
470
Not listed
280
570
30
11
890
540
1,500
480
360
Not listed
98
110
260
430
11
540
26
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N/A
N/A
N/A
N/A
N/A
H-Galden 1040x
NovecHFE-7100
Novec HFE-7200
PFPMffi
Nitrogen
Trifluoride
Trifluoromethyl
sulfur
pentafluoride
N/A
N/A
N/A
N/A
N/A
43-10pcccl24
449sl
569sf2
Not
available
Not
available
Not available
Not available
Not available
26103-08-2
Not available
Not available
163702-07-6
163702-08-7b
163702-05-4
163702-06-5b
Not available
7783-54-2
CH3OCF(CF3)2
(CF3)2CHOH
CF3CF2CH2OH
CHF2OCH(CF3)2
-(CF2)4CH(OH>
CHF2OCF2OC2F4OCHF2
C4F9OCH3
(CF3)2CFCF2OCH3b
C4F9OC2H5
(CF3)2CFCF2OC2H5b
CF3OCF(CF3)CF2OCF2OCF3
NF3
SF5CF3
343a
195
42
380a
73a
1,870
297
59
10,300
17,200
17,700
343
217
Not listed
379
72
1,870
404
57
Not listed
18,000
17,960
330
190
40
370
70
1,800
390
55
Not listed
10,800
>17,500
aListed in errata sheet updated 31 July 2008.
blnseparable isomer.
N/A = not applicable. These chemicals fall outside of the typical HFE naming convention.
GWPs listed in italics under the Third Assessment Report were determined indirectly rather than through laboratory
measurements.
The GWP for sevoflurane, a common anesthetic, has not been published in any IPCC or WMO
Assessment. However, one study estimated that the absolute GWP for sevoflurane at an infinite
time horizon was two percent of the absolute direct GWP of CFC-12 at an infinite time horizon
(Langbein, 1999). Adjusting this value to a 100-year time horizon and multiplying it by the 100-
year direct GWP given for CFC-12 in AR-4 provides a 100-year GWP for sevoflurane of 345.
2. Options for the Scope of Activities Reported
Because fluorinated GHGs and N2O have an extremely large number of relatively small
downstream sources, reporting of downstream emissions of these gases would be incomplete,
impractical, or both. On the other hand, the number of upstream producers, importers, and
exporters is comparatively small, and the quantities that would be reported by individual gas
suppliers are often quite large. Thus, upstream reporting is likely to be far more complete and
cost-effective than downstream reporting.
Downstream emissions are most closely related to the upstream quantity known as
"consumption," which is defined as the sum of the quantities of chemical produced in or
imported into the United States minus the sum of the quantities of chemical transformed (used as
a feedstock in the production of other chemicals), destroyed, or exported from the United States.
(Chemical that is exported, transformed, or destroyed will never be emitted in the United States.)
EPA reviewed a number of protocols that track chemical consumption, its components
(production, import, export, etc.), or similar quantities. These protocols included EPA's
Stratospheric Ozone Protection regulations at 40 CFR Part 82, the Australian Commonwealth
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Government Ozone Protection and Synthetic Greenhouse Gas Reporting Program, the EU
Regulation on Certain Fluorinated Greenhouse Gases (No. 842/2006), EPA's Chemical
Substances Inventory Update Rule at 40 CFR 710.43, EPA's Acid Rain regulations at 40 CFR
Part 75, the Toxic Release Inventory (TRI) Program, and the 2006 IPCC Guidelines.
EPA reviewed these protocols both for their overall scope and for their specific requirements for
monitoring and reporting. The monitoring requirements for production, transformation, and
destruction are discussed in section 4 below. (The monitoring requirements for imports and
exports are discussed in separate technical support documents.)
Four of these protocols are designed specifically to monitor the supply of a set of chemicals
within a country. These include EPA's Stratospheric Protection Program, the EU Regulation on
Certain Fluorinated Greenhouse Gases, the Australian Synthetic Greenhouse Gas Reporting
Program, and EPA's Chemical Substances Inventory Update Rule. All four of these programs
require reporting of production and imports, and the first three also require reporting of exports.
In addition, the EU regulation and EPA's Stratospheric Ozone Protection Program require
reporting of the quantities of chemicals transformed or destroyed. By accounting for all
chemical flows into and out of their respective jurisdictions, including destruction and
transformation, these two programs result in estimates of consumption that are more closely
related to actual country/regional emissions than are estimates of consumption that do not
account for all of these flows.
3. Options for Reporting Threshold
EPA evaluated a range of threshold options for facilities producing fluorinated GHGs and N2O.
These included production-based thresholds of 1,000, 10,000, 25,000 and 100,000 mtCO2e and
capacity-based thresholds equivalent to these. EPA also evaluated a requirement that all
production facilities be required to report.
The capacity thresholds were developed based on full capacity utilization. This is a somewhat
conservative assumption since capacity utilization is often below 100 percent, but production can
fluctuate, and this assumption ensures that facilities that have a reasonable chance of producing
more than the threshold quantity.
Table 2 below shows the emissions and facilities that would be covered under the various
thresholds for production and bulk imports of N2O and HFCs, PFCs, SFe, and
Table 2: Threshold Analysis for Industrial Gas Supply
Source
Category
HFC, PFC,
SF6, and NF3
Producers
Emission
Threshold
Level2
1,000
10,000
25,000
100,000
Total
National
Production
or Import
(mtCO2e)
350,000,000
350,000,000
350,000,000
350,000,000
Number of
Facilities
12
12
12
12
Production or Imports
Covered
mtCO2e/yr
350,000,000
350,000,000
350,000,000
350,000,000
Percent
100%
100%
100%
100%
Facilities Covered
Number
12
12
12
12
Percent
100%
100%
100%
100%
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Source
Category
N2O
Producers
N2O and
Fluorinated
GHG
Importers
(bulk)
Emission
Threshold
Level2
1,000
10,000
25,000
100,000
1,000
10,000
25,000
100,000
Total
National
Production
or Import
(mtCO2e)
4,500,000
4,500,000
4,500,000
4,500,000
110,024,979
110,024,979
110,024,979
110,024,979
Number of
Facilities
5
5
5
5
116
116
116
116
Production or Imports
Covered
mtCO2e/yr
4,500,000
4,500,000
4,500,000
4,500,000
110,024,987
109,921,970
109,580,067
108,703,112
Percent
100%
100%
100%
100%
100%
99.9%
99.6%
98.8%
Facilities Covered
Number
5
5
5
5
111
81
61
44
Percent
100%
100%
100%
100%
96%
70%
53%
38%
As can be seen from Table 2, all identified N2O and HFC, PFC, SFe, and NFs production
facilities would be covered at all capacity and production-based thresholds considered in this
analysis.
EPA does not have facility-specific production capacity information for the six facilities
producing fluorinated anesthetics; however, if total estimated U.S. production were evenly
divided among these six facilities, they too would be covered at all capacity and production-
based thresholds.
Either a capacity-based threshold or a requirement that all facilities report would permit facilities
to quickly determine whether or not they must report under this rule. The one potential
drawback of requiring reporting for all production facilities is that small-scale production
facilities (e.g., for research and development) could be inadvertently required to report their
production, even though the quantities produced would be small in both absolute and CCV
weighted terms.
EPA also considered a range of publications from which to draw the 100-year GWPs that
producers would use to determine whether their CO2-equivalent production exceeded the
applicable threshold. These included the IPCC Second Assessment Report (SAR) and later
IPCC and other reports (e.g., the 2006 Scientific Assessment of Ozone Depletion published by
the World Meteorological Organization.) The advantage of using the GWPs published in the
SAR is that these are the GWPs that are used for current U.S. and international reporting of CO2-
equivalent GHG emissions. The disadvantage is that the SAR does not list GWPs for some of
the fluorinated GHGs that are coming into increasing use (notably NF3 and many of the
fluorinated ethers). However, if SAR GWPs were not available, importers could use the most
recent GWP from either an IPCC Assessment Report or a WMO Scientific Assessment of Ozone
Depletion.
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4. Monitoring Methods and Current Plant Practices
a. Production
In developing the proposed rule, EPA reviewed a number of protocols for estimating production
and other flows. These include the 2006IPCC Guidelines, Title VI of the Clean Air Act (CAA),
Part 75 Appendix D (measurement requirements for oil and natural gas), the Toxic Release
Inventory (TRI), the Technical Guidelines for the Voluntary Reporting of Greenhouse Gases
(1605(b)) Program, the Toxic Substances Control Act (TSCA) Chemical Substance Inventory,
EPA's Climate Leaders Program, The Climate Registry, the EU Regulation on Certain
Fluorinated Greenhouse Gases (No. 842/2006), and the EU's Article 6 reporting. As discussed
below, EPA also reviewed the methods currently used by production facilities to measure their
production.
The accuracy and precision of measurements of production are determined by (1) the accuracy
and precision of the instruments used to measure production, and (2) the completeness with
which the various flows of product into and out of the production process are characterized. The
methods described in the protocols and guidance differ in their level of specificity regarding their
precision and accuracy requirements. Some programs, such as Title VI, TSCA, and EC's Article
6 do not specify any accuracy requirement, while other programs specifically define acceptable
errors and reference industry standards for calibrating and verifying monitoring equipment. One
of the latter is Part 75, Appendix D, which establishes requirements for measuring oil and gas
flows as a means of estimating SC>2 emissions from their combustion.
The high GWPs and large volumes of fluorinated GHGs produced make precise measurements
important for this source category. For example, a one-percent error at a typical facility
producing fluorinated GHGs would equate to 300,000 mtCC^e. Even a 0.2 percent error equates
to 60,000 mtCO2e, but 0.2 percent is near the precision limit of modern flowmeters, making
greater precision difficult. Moreover, as is discussed in the Technical Support Document for
Emissions from Production of Fluorinated GHGs (EPA-HQ-OAR-2008-0508-012), the precision
of the production measurement (as well as of the reactant and byproduct measurements) strongly
affects the precision of the estimate of emissions from the production process when the mass-
balance approach is used. EPA believes that requirements for precise and accurate
measurements (e.g., precisions and accuracies of 0.2 percent) should not represent a significant
burden to chemical producers, who already use and regularly calibrate measurement devices with
similar accuracies and precisions.
Measuring devices could be positioned wherever production of the facility is traditionally
measured, e.g., at the inlet to the day tank or at the shipping dock.
In some cases, production facilities accept used GHG product for reclamation and add this
product back into the production process. To avoid counting this used GHG product as new
production, owners or operators of facilities that produce N2O or fluorinated GHGs could be
required to measure any quantities of these GHGs that they add to the production process
upstream of the production measurement. These quantities would be subtracted from the total
mass of product measured at the end of the process.
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b. Destruction
In its evaluation of options for monitoring and reporting destruction of fluorinated GHGs, EPA
took into consideration the existing reporting requirements for ODS destruction under EPA's
Stratospheric Ozone Protection program and the proposed reporting requirements for HFC-23
destruction from the production of HCFC-22 (see Technical Support Document EPA-HQ-OAR-
2008-0508-015). A brief description of each follows. EPA also considered issues that arise in
the destruction of SFe and PFCs, which are relatively difficult to destroy.
Reporting of ODS Destruction and Transformation
Under the Stratospheric Ozone Protection Program, ODS to be destroyed or transformed can, in
some cases, be imported or produced without expending production or consumption allowances.
In these cases, producers and importers of ODS are required to report and document the amount
and type of ODS that they destroy or transform or that they sell or transfer to another company
for destruction or transformation. In addition, persons destroying or transforming ODS are
required to provide verification of destruction or transformation to producers and importers and
to EPA.
Where controlled ODS were originally produced without expending allowances, persons who
purchase or otherwise receive ODS from a producer or importer of ODS and subsequently
destroy the ODS are required to provide a destruction verification document to the producer or
importer. This verification document must include:
• the identity and address of the person intending to destroy controlled substances;
• an indication of whether those controlled substances will be "completely destroyed"
or less than completely destroyed, in which case the person must provide the DE;1
• the period of time over which the person intends to destroy the controlled substances;
and
• the signature of the verifying person.
A revised copy of the verification must be submitted to the producer or importer if any aspects of
the verification change.
Similarly, persons who purchase ODS from a producer or importer and who subsequently
transform the ODS are required to provide the producer or importer with the IRS certification
that the controlled substances will be transformed.
The producer or importer must submit a copy of the destruction verification or transformation
certification to EPA along with the names and quantities of all ODS destroyed during a control
period and a copy of the invoice or receipt documenting the sale of the controlled substance.
This receipt must include the name, address, contact person and telephone number of the
transformer or destroyer.
Additionally, those persons who destroy or transform ODS and who submitted a destruction
verification or an IRS certificate of intent to transform to a producer and/or importer are required
to report to EPA the names and quantities of ODS destroyed or transformed during the control
period (i.e. one calendar year).
1 "Completely destroy," as defined in 40 CFR Part 82.3, Subpart A, means "to cause the expiration of a controlled substance
at a destruction efficiency of 98 percent or greater, using one of the destruction technologies approved by the Parties."
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In addition to these periodic reports, persons who destroy ODS must submit to EPA a one-time
report detailing:
• the destruction unit's destruction efficiency,
• the methods used to record the volume destroyed,
• the methods used to record destruction efficiency, and
• the names of other relevant Federal or State regulations that may apply to the
destruction process.
If there are changes in a facility's destruction efficiency (DE) and/or methods used to record the
volume destroyed or used to determine DE, the facility must submit a revised report to EPA
within 60 days of the change.
Practice and Efficiency of ODS Destruction
Under the Stratospheric Ozone Protection Program, "destruction" is defined as the expiration of
a controlled substance (ODS) to the destruction efficiency actually achieved, using one of six
processes approved by the Parties to the Montreal Protocol.
Most facilities that destroy ODS in the United States are permitted hazardous waste combustors
(HWCs). U.S.-based HWCs are highly regulated entities, subject to regulation under both the
Clean Air Act (CAA) and RCRA, as well as associated state statutes and regulations. Further,
HWCs have been subjected to site-specific risk assessments (SSRAs) on a facility-specific basis
to ensure that air emissions from those facilities do not pose unacceptable risks to human health
and the environment, and any such risks identified are subject to and mitigated by risk-based
RCRA permit limits established by the permitting agency (EPA, 2007).
Facilities destroying ODS that are considered RCRA hazardous waste (specifically, some CFCs,
methyl chloroform, carbon tetrachloride, and methyl bromide) are required to meet the
applicable Maximum Achievable Control Technology (MACT) standards for HWCs, which
include the minimum destruction and removal efficiency (DRE) of 99.99 percent for RCRA
hazardous wastes. Performance testing is most often not conducted using ODS, but rather, using
a few representative compounds that are more difficult to destroy than ODS. Conducting
performance testing using ODS is possible, but would impose additional costs on facilities that
would vary depending on whether the test was conducted in conjunction with an already
scheduled performance test (EPA, 2007).
It is likely that this minimum required DRE is also being met for other ODS not listed as RCRA
hazardous wastes that are destroyed by RCRA-permitted HWCs, based on their test protocols,
permitting requirements and actual performance data. HWCs typically operate at temperatures
above 1800°F, which are believed to be sufficient to destroy CFCs, HCFCs, and halons (EPA,
2007).
Proposed Reporting ofHFC-23 Destruction
EPA is also considering requiring reporting of HFC-23 destruction as explained in the document,
"Technical Support Document for Emissions of HFC-23 from the Production of HCFC-22"
(EPA-HQ-OAR-2008-0508-015). Verifying the performance of the destruction device is
important because if the destruction device malfunctioned, were not operated properly, or were
unused for some other reason, emissions of HFC-23 from each of the U.S. HCFC-22 production
10
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plants could easily exceed all thresholds for this source category. HFC-23 destruction facilities
could be required to perform annual HFC-23 concentration measurements by gas
chromatography to confirm that emissions from the destruction device are as low as expected
based on the rated DE of the device. Although the initial testing and parametric monitoring that
facilities currently perform on their destruction device provides general assurance that the device
is performing correctly, an annual measurement would provide additional assurance at relatively
low cost (e.g., approximately two hours of technician time per year to sample and analyze the
vent gases). Even a one- or two-percent decline in the average destruction efficiency of
destruction devices could lead to emissions of more than 100,000 mtCC^e, making this a
particularly important factor to monitor accurately.
Currently, two of the three operating HCFC-22 production facilities either destroy the FIFC-23
that they generate or recapture it for destruction elsewhere. The facility that destroys the HFC-
23 on site uses a thermal oxidizer that operates at temperatures above 2,300 degrees F. In 1994,
the inlet and outlet of this thermal oxidizer were both sampled to determine the DE for HFC-23,
which was measured as greater than 99.996 percent. The facility that recaptures the HFC-23 for
destruction elsewhere (another facility owned by the same company) reports that the thermal
converter used to destroy the HFC-23 has a measured DE for HFC-23 of greater than 99.998
percent, with a non-detect concentration of HFC-23 at the outlet of the device.
Implications for Destruction of Fluorinated GHGs other than HFC-23
In view of the practices described above, EPA believes that producers of fluorinated GHGs that
also destroy fluorinated GHGs are already likely to verify the DEs of their destruction devices.
Many facilities destroying fluorinated GHGs are likely to destroy ODS as well, meaning they
must submit one-time reports providing the DE of the destruction device. Due to the HWC
MACT standards, facilities that destroy ODSs that are hazardous waste test the DEs of their
destruction devices, generally once every five years.
However, some fluorinated GHGs, particularly CF4 and SF6 are more difficult to destroy than the
reference gases (e.g., monochlorobenzene) used in existing test methods for HWCs. For
destruction of these compounds to occur, temperatures must be quite high,2 fuel must be
provided, flow rates of fuels and air (or oxygen) must be kept above certain limits, flow rates of
fluorinated GHG must be kept below others, and for some particularly difficult-to-destroy
chemicals such as CF4, pure oxygen must sometimes be fed into the process. If one or more of
these process requirements is not met, destruction efficiencies can drop sharply (in some cases,
by an order of magnitude or more), and fluorinated GHGs will simply be exhausted from the
device.
In order to verify destruction of these fluorinated GHGs, the DE would have to be verified for
these compounds. Alternatively, the DE could be verified using the most-difficult-to-destroy
compound actually processed by the destruction device. For example, if a destruction device
were used to destroy both CF4 and SFe, the verification could be performed using CF4. As noted
above, verification testing performed with reference compounds such as monochlorobenzene
will not verify destruction of either CF4 or SFe.
For example, a temperature of 2190 degrees F is required to achieve a destruction efficiency greater than 99
percent for SF6 (CIGRE, 2003), and the autoignition temperature for CF4 is similarly high.
11
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c. Equations
The total mass of fluorinated GHGs or nitrous oxide produced annually would be estimated by
using equation 1 below:
PP (Equation 1)
P=\
P = mass of fluorinated GHG or nitrous oxide produced annually
Pp = mass of fluorinated GHG or nitrous oxide produced over the period p
The total mass of fluorinated GHGs or nitrous oxide produced over the period p would be
estimated by using equation 2 below:
Pp=0p-Up (Equation 2)
where:
Pp = mass of fluorinated GHG or nitrous oxide produced over the period p (metric
tons)
Op = mass of fluorinated GHG or nitrous oxide that is measured coming out of the
production process over the period p (metric tons)
Up = mass of used fluorinated GHG or nitrous oxide that is added to the production
process upstream of the output measurement over the period p (metric tons)
Because losses may occur between the point where the total production of the fluorinated GHG
is measured and the point where the fluorinated GHG is reacted as a feedstock (transformed), it
may be appropriate to require that that facilities separately measure and report the production
that is fed into the process for which the fluorinated GHG is used as a feedstock, using scales or
flowmeters on the equipment used for that process. .
In this case, the total mass of fluorinated GHGs or nitrous oxide transformed would be estimated
by using equation 3 below:
T = FT-R (Equations)
where:
T = mass of fluorinated GHG or nitrous oxide transformed annually (metric tons)
FT = mass of fluorinated GHG fed into the transformation process annually (metric
tons)
R = mass of residual, unreacted fluorinated GHG or nitrous oxide that is
permanently removed from the transformation process
Facilities producing fluorinated GHGs could calculate the quantities of GHG that they destroy,
using equation 4 below:
D = FD*DE (Equation 4)
where:
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D = mass of fluorinated GHG destroyed annually (metric
tons)
FD = mass of fluorinated GHG fed into the destruction
device annually (metric tons)
DE = Destruction Efficiency of the destruction
device (fraction)
EPA is proposing that weigh scales and flowmeters be calibrated every year or sooner if an error
is suspected based on mass-balance calculations or other information. Facilities could perform
the verification and calibration of their scales and flowmeters during routine product line
maintenance. EPA understands that some types of flowmeters that are commonly employed in
chemical production, such as the Coriolis type, may require less frequent calibration.
d. Relationship of proposed requirements to current plant practices
The current best practices of the fluorinated gas industry include accurate monitoring techniques,
reducing the burden of a rule.
Industry representatives from leading manufacturers were contacted on several occasions,
throughout the scope of this assessment project, to ascertain current plant practices as they
related to:
• general process flow streams; and
• quantitative techniques for measuring production of finished product produced, various
by-product streams, waste streams, common practices, and the ability to measure process
emissions.
The production process occurs in several stages. First, raw materials are transferred into a
reactor. After reaction, the product goes through a distillation and purification process step, and
is then held in a short term storage tank, known as a "day tank" where finished product is
verified to meet a finished product specification. Once the product has met specification, it is
transferred to a larger storage tank (approximately 1 MM Ibs. capacity) where it is contained
until, packing-off, loading and distribution.
Production yield is measured by reconciling the following streams in the process:
• measure of reactants into the reactor
• measure of waste or by-product
• measure of "finished product" collected
• amount of process losses, including fugitive emissions, lost during manufacturing,
loading and transfer of finished product to customer storage tanks
Manufacturing plants use either weigh scales/load cells (a load cell is the actual "weight sensor"
mechanism within a weigh scale) or flowmeters to measure the quantities of materials passing
through various points in the production line. Weigh scales provide a reliable, repeatable, and
accurate weight of fluorinated GHGs. Weigh scale accuracies typically are in the range of+/-
0.02 - 0.05%. This range is quoted on scale specifications by leading manufacturers and
supported by bulk weighing specifications quoted as +/- 0.03-0.04%.
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The most accurate type of flowmeters are Coriolis flowmeters. An advantage of Coriolis
flowmeters is that it measures the mass flow rate directly, which eliminates the need to
compensate for changing temperature, viscosity, and pressure conditions. Coriolis flowmeters
can be purchased with accuracies quoted through specifications at +/- 0.15%, however, the more
common flowmeter accuracy for industry-wide use approaches +7-0.5%.
Pro and cons to Coriolis flowmeters are as follows:
Pros:
• Higher accuracy than most flowmeters;
• Can be used in a wide range of liquid flow conditions;
• Capable of measuring hot and cold fluid flow;
• Low pressure drop; and
• Suitable for bi-directional flow
Cons:
• High initial set up cost;
• Clogging may occur and difficult to clean;
• Larger in over-all size compared to other flowmeters; and
• Limited line size availability.
Flowmeters are commonly used by some manufacturers for process control as reactants enter the
reactor, and as product enters each tank. Exact flowmeter locations can be:
• in lines measuring reactants loading the reactor
• in the lines of waste 7 by-products
• in the line leading to the "day tank", measuring daily finished product manufactured
Even when these flow meters are not primarily used to estimate production, they can be used for
secondary production checks. Flow of pure HFC into the day tank can be collected on a daily
basis. Flow meters are not placed as product is released from the reactor, as it has yet to go
through the purification process. As such, the first true point in the process where measurements
of a purified product without impurities can be taken is just prior to entering the "day tank".
Whatever type of measurement device they use, fluorinated GHG producers track production at
each stage of the production process. Daily and monthly mass balancing is usually completed
for each product produced. Percent yield is a very important for the fluorinated GHG producers;
it represents the amount of starting materials used, minus impurities sent to a destruction device,
minus losses which are unaccounted for, yielding an amount of prime final product which is
available for sale. This calculation is commonly done on a daily basis and then reconciled
monthly with the sales of the product.
5. Procedures for Estimating Missing Data
If a facility regularly used upstream (i.e., at the entrance to the day tank) weigh scales to estimate
production, a downstream estimate of production (i.e., quantity shipped) could be used in the
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event that the upstream scale failed to meet an accuracy test, malfunctions, or was rendered
inoperable. In this case, it might be appropriate for a facility to add some percentage (e.g., 1.5
percent) to the quantity measured using the downstream estimation procedure to compensate for
losses from distribution and packaging.
In the event that neither an upstream nor a downstream methodology were feasible, a facility
could calculate production based upon the consumption of reactants and assuming a complete
stoichiometric conversion.
It is believed that production levels will be readily available, since business targets are reliant on
accurate monitoring and reporting of production.
In cases where there is a missing value of the mass fed into the transformation processes or sent
to another facility for transformation, a facility could use the arithmetic average of the quality-
assured values of that parameter immediately preceding and immediately following the missing
data incident.
A missing value allowance for the annual destruction device outlet concentration measurement,
which is only required once a year, should not be necessary. A re-test could be performed if the
data from the annual destruction device outlet concentration measurement are determined to be
unacceptable or not representative of typical operations.
6. QA/QC Requirements
Typical QA/QC requirements for measuring devices include initial and periodic verification and
calibration. (For example, see the requirements of EPA's Acid Rain regulations at 40 CFR Part
75.) In this case, it would be appropriate to require an initial verification of flowmeters and
weigh scales and periodic calibration in accordance with the applicable industry standards.
Calibration of flowmeters and scales could be performed prior to the reporting year; after the
initial calibration, recalibration could be performed at least annually or more frequent if specified
by the manufacturer. Under this approach, producers could perform the verification and
calibration of their weigh scales during routine product line maintenance.
For the gas chromatography analytical method described under the monitoring section of this
document, monthly calibration, using known certified standards should be used. The calibration
involves validating accurate measurement of these fluorocarbon standards across a range of
possible concentrations, depending on which process streams are being measured.
7. Reporting Procedures
The following data would be useful for confirming production calculations and/or calculating
emission rates that could be compared across facilities and over time for quality control
purposes:
• Total mass of fluorinated GHG or N2O produced;
• Total mass of fluorinated GHG or N2O transformed;
• Total mass of fluorinated GHG destroyed;
• Data on total mass of reactants fed into the production process;
• Total mass of non-GHG reactants and byproducts permanently removed from the
process;
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• Mass of used product added back into the production process;
• Total mass of any fluorinated GHG or nitrous oxide sent to another facility for
transformation;
• Total mass of any fluorinated GHG sent to another facility for destruction; and
• The names and addresses of other facilities to which N2O or fluorinated GHGs were sent
for transformation or destruction.
For facilities destroying fluorinated GHGs, useful data would include the results of the annual
fluorinated GHGs concentration measurements at the outlet of the destruction device, including:
(1) the flow rate of the fluorinated GHGs being fed into the destruction device (in kg/hour); (2)
the concentration (mass fraction) of fluorinated GHGs at the outlet of the destruction device; (3)
the flow rate at the outlet of the destruction device (in kg/hr); and (4) the calculated emission rate
based on the data provided in numbers (2) and (3). Additionally, these facilities could be
required to submit a one-time report including the following: the destruction unit's DE, the
methods used to record volume destroyed and to measure and record DE, and the names of other
relevant federal or state regulations that may apply to destruction process. This one-time report
could be very similar to that required under EPA's Stratospheric Ozone Protection regulations.
The submittal of a revised report would be required if any process changes occur that affect the
unit destruction efficiency or the methods used to record destruction.
8. Recordkeeping Procedures
The following records would be very useful for verifying production, transformation, and
destruction estimates and related quantities and calibrations.
Owners or operators of facilities producing N2O or fluorinated GHGs could be required to keep
records of the data used to estimate production, as well as records documenting the initial and
periodic calibration of the flowmeters or scales used to measure production.
Owners or operators of production facilities using N2O or fluorinated GHGs as feedstocks could
be required to keep records documenting: the initial and annual calibration of the flowmeters or
scales used to measure the mass of GHG fed into the destruction device and the periodic
calibration of gas chromatographs used to analyze the concentration of fluorinated GHG in the
product for which the GHG is used as a feedstock.
Owners or operators of GHG production facilities that destroy fluorinated GHGs could be
required to keep records documenting: the information that they send in the one-time and annual
reports, the initial and annual calibration of the flowmeters or scales used to measure the mass of
GHG fed into the destruction device, the method for tracking startups, shutdowns, and
malfunctions and any GHG emissions during these events, and the periodic calibration of GCs
used to annually analyze the concentration of fluorinated GHG in the destruction device exhaust
stream, as well as the representativeness of the conditions under which the measurement took
place.
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9. References
EPA (2007) CDS Destruction in the United States. Revised Draft. Prepared by ICF
International for U.S. EPA's Stratospheric Protection Division. April 2007.
Folland, C.K., T.R. Karl, J.R. Christy, R.A. Clarke, G.V. Gruza, J. Jouzel, M.E. Mann, J.
Oerlemans, MJ. Salinger and S.-W. Wang (2001) Observed Climate Variability and
Change. In: Climate Change 2001: The Scientific Basis. Contribution of Working Group
I to the Third Assessment Report of the Intergovernmental Panel on Climate Change,
Houghton, J.T.,Y. Ding, D. J. Griggs, M. Noguer, P. J. van der Linden, X. Dai, K.
Maskell, and C. A. Johnson (eds.). Cambridge University Press, Cambridge, United
Kingdom and New York, NY, USA.
IPCC (2007) Climate Change 2007: The Physical Science Basis. Contribution of
Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change, Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt,
M. Tignor and H.L. Miller (eds.). Cambridge University Press, Cambridge, United
Kingdom and New York, NY, USA.
IPCC (2006) 2006 IPCC Guidelines for National Greenhouse Gas Inventories. The
National Greenhouse Gas Inventories Programme, The Intergovernmental Panel on
Climate Change, H.S. Eggleston, L. Buendia, K. Miwa, T. Ngara, and K. Tanabe (eds.).
Hayama, Kanagawa, Japan.
Langbein, T., H. Sonntag, D. Trapp, A. Hoffmann, W. Malms, E.-P. Roth, V. Mors and
R. Zellner (1999) "Volatile anaesthetics and the atmosphere: atmospheric lifetimes and
atmospheric effects of halothane, enflurane, isoflurane, desflurane and sevoflurane."
British Journal of Anaesthetics 82 (1): 66-73.
Process Engineering Managers at Honeywell, MDA, and Dupont: Multiple interviews
throughout 2008.
WMO (World Meteorological Organization) (2007) Scientific Assessment of Ozone
Depletion: 2006, Global Ozone Research and Monitoring Project - Report No. 50.
Geneva, Switzerland.
Product Websites:
Coriolis flow meters:
Micro Motion: www.emersonprocess.com/MicroMotion/
Siemens: https://pia.khe.siemens.com/index7625.htm
Weigh Scales / Weigh Cells
Mettler Toledo: www.mt.com or
http://us.mt.com/mt/filters/products-applications_industrial-weighing/
American Weigh Scales: www.americanweigh.com
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