Technical Support Document for the Adipic Acid
Production Sector: Proposed Rule for Mandatory
Reporting of Greenhouse Gases
Office of Air and Radiation
U.S. Environmental Protection Agency
January 22, 2009
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
CONTENTS
1. Industry Description 1
2. Total Emissions 2
2.1 Process Emissions 2
2.2 Stationary Combustion 2
3. Review of Existing Programs and Methodologies 4
3.1 2006 IPCC Guidelines 4
3.2 WRI/WBCSD Protocol 4
3.3 2008 U.S. Inventory of Greenhouse Gas Emissions and Sinks 5
3.4 The Climate Registry 5
3.5 Technical Guidelines Voluntary Reporting of Greenhouse Gases (1605(b))
Program 5
3.6 Environment Canada's Technical Guidance on Reporting Greenhouse Gas
Emissions 5
4. Options Considered for Reporting Threshold 6
4.1 Emissions Thresholds 6
4.2 Capacity Thresholds 6
4.3 No Emissions Threshold 6
5. Options for Monitoring Methods 7
5.1 Option 1: Simplified Emissions Calculation 7
5.2 Option 2: Stack Testing 8
5.3 Option 3: Direct Measurement 10
6. Options for Estimating Missing Data 11
6.1 Procedures for Option 1: Simplified Emissions Calculation 11
6.2 Procedures for Option 2: Stack Testing 11
6.3 Procedures for Option 3: Direct Measurement 11
6.3.1 Continuous Emission Monitoring Data CEMS 11
6.3.2 Stack Testing Data 13
7. QA/QC Requirements 14
7.1 Stationary Emissions 14
7.2 Process Emissions 14
7.2.1 Continuous Emission Monitoring System (CEMS) 14
7.2.2 Stack Test Data 14
7.3 Data Management 15
8. Types of Emission Information to be Reported 16
8.1 Types of Emissions to be Reported 16
8.2 Other Information to be Reported 16
8.3 Additional Data to be Retained Onsite 16
9. References 17
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
1. Industry Description
Adipic acid is a white crystalline solid used in the manufacture of synthetic fibers, plastics,
coatings, urethane foams, elastomers, and synthetic lubricants. Commercially, it is the most
important of the aliphatic dicarboxylic acids, which are used to manufacture polyesters.
Eighty-four percent of all adipic acid produced in the United States is used in the production of
6,6-nylon, nine percent is used in the production of polyester polyols, four percent is used in
the production of plasticizers, and the remaining four percent is accounted for by other uses,
including unsaturated polyester resins and food applications (ICIS 2007). Food grade adipic
acid is used to provide some foods with a "tangy" flavor (Thiemens and Trogler 1991; EPA
2008).
Worldwide, few adipic acid plants exist. The United States and Europe are the major
producers. The United States has three companies in four locations accounting for 34 percent
of world production, and eight European producers account for a combined 38 percent of
world production (CW 2007).
Adipic acid is produced through a two-stage process during which N2O is generated in the
second stage. The first stage of manufacturing usually involves the oxidation of cyclohexane
to form a cyclohexanone/cyclohexanol mixture. The second stage involves oxidizing this
mixture with nitric acid to produce adipic acid. The N2O is generated as a by-product of the
nitric acid oxidation stage and is emitted in the waste gas stream (Thiemens and Trogler 1991).
A representation of the process is shown below.
(CH2)5CO (Cyclohexanone) + (CH2)5CHOH (Cyclohexanol) + WHNO3 —~
HOOC(CH2)4COOH (Adipic Acid) + xN20 + yH20
Process emissions from the production of adipic acid vary with the types of technologies and
level of emission controls employed by a facility. In 1990, two of the three major adipic acid-
producing plants had N20 abatement technologies in place and, as of 1998, the three major
adipic acid production facilities had control systems in place. Only one small plant,
representing approximately two percent of production, does not control N20 emissions (IPCC
2006; EPA 2008).
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
2. Total Emissions
Process-related N2O emissions and stationary combustion emissions from adipic acid
production were estimated to be 9,297,866 metric tons C02e in 2006. Process N2O emissions
alone were estimated at 5,921,434 metric tons C02e. Stationary combustion emissions were
estimated at 3,376,432 mtCC^e. National adipic acid production has increased by
approximately 36 percent over the period of 1990 through 2006, to approximately one million
metric tons. At the same time, emissions have been reduced by 61 percent due to the
widespread installation of pollution control measures in the late 1990s (EPA 2008).
2.1 Process Emissions
Process related estimates of N2O from adipic acid production were derived for the U.S.
Inventory, and are estimated at 5,921,434 metric tons C02e in 2006. Facility-specific data is
Confidential Business Information (CBI) for two plants. Consequently, the detailed facility-
level data are not presented here.
2.2 Stationary Combustion
Adipic acid production facilities consume fossil fuels for stationary combustion which
contribute to their GHG emission total. GHG (CO2, CH4, and N2O) emissions from on-site
fossil fuel combustion were estimated using data collected through title V permitting for two of
the four production facilities, as well as CO2 emission factors, which were derived using heat
content and carbon content data contained in the Inventory of U.S. Greenhouse Gas Emissions
and Sinks 1990-2006. Emission factors for CO2 were derived from Table 2.3 of the 2006 IPCC
Guidelines for National Greenhouse Gas Inventories (IPCC 2006). These carbon content
factors are for Manufacturing Industries and Construction and apply to stationary source
combustion CO2 emissions, not process N2O emissions. They are presented in Table 1. For
more information on combustion related N20 and CH4 emissions refer to the stationary
combustion Technical Support Document in EPA-HQ-OAR-2008-0508-004.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
Table 1 - Heat and Carbon Contents Provided by the Inventory of U.S. Greenhouse Gas
Emissions and Sinks 1990-2006
Fuel Category
Fuel Type
Heat Content
Carbon Content
Value
Unit
(Tg Carbon/QBTU)
Solid Fuels
Anthracite Coal
22.57
MMBtu/Short T on
28.26
Bituminous Coal
23.89
MMBtu/Short T on
25.49
Sub-bituminous Coal
17.14
MMBtu/Short T on
26.48
Lignite
12.87
MMBtu/Short T on
26.30
Coke
24.80
MMBtu/Short T on
31.00
Unspecified
25.97
MMBtu/Short T on
25.34
Gas Fuels
Natural Gas
1,029
Btu/ft3
14.47
Liquid Fuels
Crude Oil
5.80
MMBtu/Barrel
20.33
Nat Gas Liquids and LRGs
3.71
MMBtu/Barrel
16.99
Other Liquids
5.83
MMBtu/Barrel
20.33
Motor Gasoline
5.22
MMBtu/Barrel
19.33
Aviation Gasoline
5.05
MMBtu/Barrel
18.87
Kerosene
5.67
MMBtu/Barrel
19.72
Jet Fuel
5.67
MMBtu/Barrel
19.33
Distillate Fuel
5.83
MMBtu/Barrel
19.95
Residual Oil
6.29
MMBtu/Barrel
21.49
Naphtha for Petrofeed
5.25
MMBtu/Barrel
18.14
Petroleum Coke
6.02
MMBtu/Barrel
27.85
Other Oil for Petrofeed
5.83
MMBtu/Barrel
19.95
Special Naphthas
5.25
MMBtu/Barrel
19.86
Lubricants
6.07
MMBtu/Barrel
20.24
Waxes
5.54
MMBtu/Barrel
19.81
Asphalt/Road Oil
6.64
MMBtu/Barrel
20.62
Still Gas
6.00
MMBtu/Barrel
17.51
Misc. Products
5.80
MMBtu/Barrel
20.33
Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2006
Combustion-related emissions were estimated by averaging the sum of calculated emissions by
unit type (e.g. boiler, generator, etc.) from two of the adipic acid plants.. The average
combustion emissions were assumed to apply to all four plants. It was also assumed that 100
percent of the emissions from the stationary combustion sources are attributed to adipic acid
production, even though there are other processes at the adipic acid plants that may be using
steam or electricity from the stationary combustion equipment. The total calculated
combustion emissions are shown in Table 2, along with process-related emissions from all four
adipic acid plants. Detailed facility information is not provided given the small number of
facilities and confidential information.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
3. Review of Existing Programs and Methodologies
In evaluating monitoring options for adipic acid production, multiple GHG emissions reporting
guidance documents were consulted. These include documents developed by the U.S.
Environmental Protection Agency (USGHG, 2008), the Intergovernmental Panel for Climate
Change (IPCC, 2006), the Climate Registry (CR, 2007), the World Business Council for
Sustainable Development (WBCSD, 2001), and the U.S. Department of Energy (USDOE,
2007). The main monitoring methods from each of these reporting programs are reviewed
below.
3.1 2006 IPCC Guidelines
The Tier 1 methodology estimates emissions using the total production of adipic acid and the
appropriate default emission factor (300 kg N20/metric ton adipic acid). The Tier 1 method
should be applied assuming no abatement of N2O emissions and the use of the highest default
emission factor based on technology type. The Tier 2 methodology estimates emissions using
facility-specific information, including the production rate of adipic acid, the default emission
factor, the destruction factor for abatement technology, and the utilization factor of the
abatement system (if applicable). The equation is shown below. The Tier 3 methodology
estimates emissions using plant level production data and plant level emission factors that are
obtained from direct measurement of emissions. These may be derived from periodic sampling
of N2O or periodic emissions monitoring of N2O over a period that reflects the usual pattern of
operation of the plant.
ENfi = Y^EF>*AAP1 * (' - DFJ * ASUF,))
where:
En2o = emissions of N2O, kg
EF; = N2O emission factor for technology type i, kg N20/metric ton adipic
acid produced
AAP; = adipic acid production from technology type i, metric tons
DFj = destruction factor for abatement technology type j, fraction
ASUFj = abatement system utilization factor for abatement technology type j,
fraction.
3.2 WRI/WBCSD Protocol
Approach 1 involves precise direct monitoring of N2O emissions, with measurements at both
the exit stream and the uncontrolled stream. Data quality is satisfactory when measurement
data are only available for the exit stream. Approach 2 involves site-specific N2O emission
factors. This approach is based on IPCC Tier 2 methodology. Approach 3 involves the use of
default emission factors for N2O emissions. This approach is based on IPCC Tier 1
methodology.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
3.3 2008 U.S. Inventory of Greenhouse Gas Emissions and Sinks
The Tier 2 and 3 methodologies were used for adipic acid production. For two production
plants, 1990 to 2002 emission estimates were obtained directly from the plant engineer and
account for reductions due to control systems in place at these plants during the time series
(Childs 2002, 2003). These estimates were based on continuous emissions monitoring
equipment installed at the two facilities. Reported emission estimates for 2003 to 2006 were
unavailable and, thus, were calculated by applying 4.4, 4.2, 0.0, and 0.0 percent national
production growth rates, respectively.
For the other two plants, N2O emissions were calculated by multiplying adipic acid production
by an IPCC 2006 emission factor (i.e., N2O emitted per unit of adipic acid produced) and
adjusting for the percentage of N2O released as a result of plant-specific emission controls.
Emissions are estimated using the following equation:
N2O emissions = (production of adipic acid [metric tons of adipic acid]) x (0.3 metric tons N2O
/ metric ton adipic acid) x (1 - [N2O destruction factor x abatement system utility factor])
3.4 The Climate Registry
The Tier A2 methodology is a mass balance approach based on plant-specific factors for
destruction and utilization factors for an abatement technology and N2O emission factor based
on direct measurements. The Tier B methodology is a mass balance approach based on default
N2O emission factors by technology type. This methodology is consistent with Tier 2
methodology from IPCC.
3.5 Technical Guidelines Voluntary Reporting of Greenhouse Gases (1605(b))
Program
The "A" rated approach involves continuous emission monitoring from confined and
uncontrolled streams. If pollutant information is not available for uncontrolled streams,
monitoring of confined streams only is acceptable. If continuous monitoring is not possible,
emissions can be estimated using an emission factor based on direct, periodic measurements of
plant emissions. Emission factors must account for emission rates and abatement system
efficacy and frequency of use of abatement technologies. The "B" rated approach involves the
use of default IPCC emission factors and production if plant-level emission information is not
available. The "C" rated approach involves the use of estimates based on "other published
default values."
3.6 Environment Canada's Technical Guidance on Reporting Greenhouse Gas
Emissions
The guidance for mandatory reporting in Canada primarily references the IPCC guidelines.
There is no specific guidance on adipic acid production.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
4. Options Considered for Reporting Threshold
4.1 Emissions Thresholds
Four reporting threshold levels were considered for the adipic acid manufacturing sector. The
emission thresholds, 100,000, 25,000, 10,000, and 1,000 mtCC^e per year, were analyzed
based on production data.
Table 2 provides the emission threshold analysis which estimated total emissions of 9,297,866
mtC02e. This total was the sum of process emissions (5,921,434 mtCC^e) and combustion
emissions (3,376,432 mtCC^e). All plants would be covered at all production-based
thresholds. These results are summarized in Table 2.
Table 2. Threshold Analysis for Adipic Acid Production
Threshold
Level
(Metric
Tons)
Process
Emissions
(Tons
C02e/yr)
co2
Emissions
(Tons/yr)
Total
National
Emissions
(Tons
C02e)
Number
of
Entities
Emissions Covered
Entities Covered
Tons
C02e/yr
Percent
Number
Percent
100,000
5,921,434
3,376,432
9,297,866
4
9,297,866
100%
4
100%
25,000
5,921,434
3,376,432
9,297,866
4
9,297,866
100%
4
100%
10,000
5,921,434
3,376,432
9,297,866
4
9,297,866
100%
4
100%
1,000
5,921,434
3,376,432
9,297,866
4
9,297,866
100%
4
100%
4.2 Capacity Thresholds
Capacity-based thresholds are not presented here because each of the four plants exceeds
highest emissions-based thresholds.
4.3 No Emissions Threshold
The no emissions threshold includes all adipic acid production facilities regardless of their
emissions or capacity.
The option of requiring all adipic acid production facilities regardless of their emissions profile
is similar to the emissions threshold option because at each emission threshold level all adipic
acid facilities would be reporting.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
5. Options for Monitoring Methods
5.1 Option 1: Simplified Emissions Calculation
A simplified emissions calculation option would use the default emission factors established by
the Intergovernmental Panel on Climate Change (IPCC, 2006).
Two different approaches could be used.
Approach 1. Use the default emission factors and apply to the total facility production of
adipic acid. When applying this approach, no abatement of N2O emissions is considered.
N2O Emissions from Adipic Acid Production - IPCC (2006) TIER 1 Approach:
En20 = EF x AAP
Where
En2o = N2O emissions, kg
EF = N2O emission factor (default), kg N20/metric ton adipic acid produced
AAP = adipic acid production, metric tons
Approach 2. Use the default emission factors on a site-specific basis using the Tier 2 approach
established by the IPCC. These emission factors are dependent on the type of abatement
technology used. The amount of N2O emissions are determined by multiplying the emission
factor by the production level of adipic acid.
This is consistent with the Tier 2 methodology from IPCC, the Tier B methodology from The
Climate Registry, and the "B" rated approach from USDOE.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
5.2 Option 2: Stack Testing
Follow the Tier 3 approach established by IPCC using non-continuous monitoring. Use non-
continuous direct monitoring of N2O emissions and determine the relationship between adipic
acid production and the amount of N2O emissions; i.e., develop a site-specific emissions factor.
The site-specific emissions factor and production rate (activity level) is used to calculate the
emissions. Annual testing of N2O emissions would also be required to verify the emission
factor over time. Testing should be conducted without using any NOx or N2O abatement
technologies. Testing would also be required whenever significant process changes are made.
This approach is consistent with the Tier 3 methodology from IPCC, the Tier A1 methodology
from the Climate Registry, and Approach 1 from WBCSD.
Emissions would be calculated according to the following equations.
The average site-specific emission factor for the process would be calculated according to the
following equation:
V"1 CN2o *1.14x10 *Q
4- p
EFnIO
Where:
EFN20 = Average site-specific N2O emissions factor (lb N20/ton adipic
acid produced, 100 percent acid basis)
Cn2o = N2O concentration during performance test (ppm N2O)
1.14x 10"7 = Conversion factor (lb/dscf-ppm N2O)
Q = Volumetric flow rate of effluent gas (dscf/hr)
P = Production rate during performance test (tons adipic acid
produced per hour (100 percent acid basis))
n = Number of test runs
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
The N2O emissions for the process are then calculated by multiplying the emission factor by
the total production, according to following equation:
EFN20* Pa*{\-DFN)*AFN
2° 2205
Where:
En2o = N2O mass emissions per year (metric tons of N2O)
EFN20 = Site-specific N2O emission factor (lb N20/ton acid produced, 100
percent acid basis)
Pa = Total production for the year (ton acid produced, 100 percent acid basis)
DFn = Destruction factor of N2O abatement technology (percent of N2O
removed from air stream)
AFn = Abatement factor of N2O abatement technology (percent of year that
abatement technology was used)
2205 = Conversion factor (lb/metric ton).
For direct measurement using stack testing, sampling equipment would be periodically brought
to the site and installed temporarily in the stack to withdraw a sample of the stack gas and
measure the flow rate of the stack gas. Similar to CEMS, for stack testing the emissions are
calculated from the concentration of GHGs in the stack gas and the flow rate of the stack gas.
The difference between stack testing and continuous monitoring is that the CEMS data provide
a continuous measurement of the emissions, while a stack test provides a periodic
measurement of the emissions.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
5.3 Option 3: Direct Measurement
For industrial source categories for which the process emissions and/or combustion GHG
emissions are contained within a stack or vent, direct measurement constitutes either
measurements of the GHG concentration in the stack gas and the flow rate of the stack gas
using a CEMS, or periodic measurement of the GHG concentration in the stack gas and the
flow rate of the stack gas using periodic stack testing. Under either a CEMS approach or a
stack testing approach, the emissions measurement data would be reported annually.
Elements of a CEMS include a platform and sample probe within the stack to withdraw a
sample of the stack gas, an analyzer to measure the concentration of the GHG (e.g., CO2) in the
stack gas, and a flow meter within the stack to measure the flow rate of the stack gas. The
emissions are calculated from the concentration of GHGs in the stack gas and the flow rate of
the stack gas. A CEMS continuously withdraws and analyzes a sample of the stack gas and
continuously measures the GHG concentration and flow rate of the stack gas.
Follow the Tier 3 approach established by IPCC using continuous monitoring. Use CEMS to
directly measure N2O concentration and flow rate to directly determine N2O emissions. This
option is available but is not currently being used in the adipic acid production sector. This is
consistent with the Tier 3 approach established by IPCC, the Tier A1 methodology from the
Climate Registry, Approach 1 from WBCSD, and the "A" rated approach from USDOE.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
6. Options for Estimating Missing Data
Options and considerations for missing data vary will vary depending on the proposed
monitoring method. Each option would require a complete record of all measured parameters
as well as parameters determined from company records that are used in the GHG emissions
calculations (e.g., carbon contents, monthly fuel consumption, etc.).
6.1 Procedures for Option 1: Simplified Emissions Calculation
If facility-specific production data is missing for one year, an average value using the
production data from the year prior and the year after the missing year may be calculated.
Default emission factors are readily available through IPCC guidelines (IPCC 2006).
In general, adipic acid default emission factors are fairly certain because they are derived from
the stoichiometry of an intended chemical reaction (nitric acid oxidation) and N20-specific
abatement systems. The uncertainty in the emission factor for adipic acid represents variability
in N2O generation due to differences in the composition of the cyclohexanone and
cyclohexanol feedstock (i.e. ketone and alcohol) that are used by different manufacturers.
Higher ketone content results in increased N2O generation, whereas higher alcohol content
results in less N2O generation (Reimer 1999). An individual plant should be able to determine
the production of N2O (based on HNO3 consumption) within 1%. The uncertainty associated
with adipic acid production may be more significant when converted into N2O emissions. A
properly maintained and calibrated monitoring system can determine emissions to within ±5%
at the 95% confidence level (IPCC 2006).
6.2 Procedures for Option 2: Stack Testing
For process sources that use the stack testing approach, the following data are needed on a
monthly basis: adipic acid production rate, adipic acid production capacity, number of
operating hours, emission rate factor, and the type of abatement technology used and its
utilization factor. In general, the substitute data value would be the arithmetic average of the
quality-assured values of that same parameter immediately preceding and immediately
following the missing data incident. If no quality-assured data are available prior to the
missing data incident, the substitute data value would be the first quality-assured value
obtained after the missing data period. For missing oil or gas flow rates, the rule would require
using the standard missing data procedures in section 2.4.2 of appendix D to part 75.
6.3 Procedures for Option 3: Direct Measurement
6.3.1 Continuous Emission Monitoring Data CEMS
CEMS for monitoring N2O emissions are not currently in use in the industry and there is no
existing EPA method for certifying N2O CEMS. In general, the missing data procedures for
CO2 CEMS, listed below would be adequate.
For options involving direct measurement of CO2 flow rates or direct measurement of CO2
emissions using CEMS, Part 75 establishes procedures for management of missing data.
Procedures for management of missing data are described in Part 75.35(a), (b), and (d). These
procedures for managing missing data for CO2 CEMS would also apply to missing data for
N2O CEMS. In general, missing data from operation of the CEMS may be replaced with
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
substitute data to determine the N2O flow rates or N2O emissions during the period in which
CEMS data are missing.
Under Part 75.35(a), the owner or operator of a unit with a CO2 continuous emission
monitoring system for determining CO2 mass emissions in accordance with Part 75.10 (or an
O2 monitor that is used to determine CO2 concentration in accordance with appendix F to this
part) shall substitute for missing CO2 pollutant concentration data using the procedures of
paragraphs (b) and (d) of this section. Subpart (b) covers operation of the system during the
first 720 quality-assured operation hours for the CEMS. Subpart (d) covers operation of the
system after the first 720 quality-assured operating hours are completed. These procedures
would generally apply to N2O CEMS as well as CO2 CEMS.
Under Part 75.35(b), during the first 720 quality assured monitor operating hours following
initial certification at a particular unit or stack location (i.e., the date and time at which quality
assured data begins to be recorded by a CEMS at that location), or (when implementing these
procedures for a previously certified CO2 monitoring system) during the 720 quality assured
monitor operating hours preceding implementation of the standard missing data procedures in
paragraph (d) of this section, the owner or operator shall provide substitute CO2 pollutant
concentration data or substitute CO2 data for heat input determination, as applicable, according
to the procedures in Part 75.31(b). [Note that for CEMS that are measuring process N2O
emissions the term "heat input determination" may be replaced by the term "raw material
input determination."]
Under Part 75.35(d), upon completion of 720 quality assured monitor operating hours using the
initial missing data procedures of Part 75.31(b), the owner or operator shall provide substitute
data for CO2 concentration or substitute CO2 data for heat input determination, as applicable, in
accordance with the procedures in Part 75.33(b) except that the term " CO2 concentration" shall
apply rather than "SO2 concentration," the term " CO2 pollutant concentration monitor" or "
CO2 diluent monitor" shall apply rather than "SO2 pollutant concentration monitor," and the
term "maximum potential CO2 concentration, as defined in section 2.1.3.1 of appendix A to
this part" shall apply, rather than "maximum potential SO2 concentration." [Note that for
CEMS that are measuring process N2O emissions the term "heat input determination" may be
replaced by the term "raw material input determination."]
CEMS can also be used to measure the stationary combustion emissions of CO2 from boilers at
the adipic acid plants. Note that the CEMS procedures used for the N2O CEMS system for
process emissions described above would be the same as the CEMS procedures used for the
CO2 CEMS for stationary combustion emissions.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
6.3.2 Stack Testing Data
For options involving direct measurement of flow rates or emissions using stack testing,
"missing data" is not generally anticipated. Stack testing conducted for the purposes of
compliance determination is subject to quality assurance guidelines and data quality objectives
established by the U.S. EPA, including the Clean Air Act National Stack Testing Guidance
published in 2005 (USEPA 2005). The 2005 EPA Guidance Document indicates that stack
tests should be conducted in accordance with a pre-approved site-specific test plan to ensure
that a complete and representative test is conducted. Results of stack tests that do not meet
pre-established quality assurance guidelines and data quality objectives would generally not be
acceptable for use in emissions reporting, and any such stack test would need to be re-
conducted to obtain acceptable data.
The U.S. EPA regulations for performance testing under 40 CFR § 63.7(c)(2)(i) state that
before conducting a required performance test, the owner/operator is required to develop a site-
specific test plan and, if required, submit the test plan for approval. The test plan is required to
include "a test program summary, the test schedule, data quality objectives, and both an
internal and external quality assurance (QA) program" to be applied to the stack test. Data
quality objectives are defined under 40 CFR § 63.7(c)(2)(i) as "the pre-test expectations of
precision, accuracy, and completeness of data." Under 40 CFR § 63.7(c)(2)(ii), the internal
QA program is required to include, "at a minimum, the activities planned by routine operators
and analysts to provide an assessment of test data precision; an example of internal QA is the
sampling and analysis of replicate samples." Under 40 CFR § 63.7(c)(2)(iii) the external QA
program is required to include, "at a minimum, application of plans for a test method
performance audit (PA) during the performance test." In addition, according to the 2005
Guidance Document, a site-specific test plan should generally include chain of custody
documentation from sample collection through laboratory analysis including transport, and
should recognize special sample transport, handling, and analysis instructions necessary for
each set of field samples (USEPA 2005).
The U.S. EPA anticipates that test plans for stack tests that are expected to be used to obtain
data for the purposes of emissions reporting would be made available to EPA prior to the stack
test and that the results of the stack test would be reviewed against the test plan prior to the
data being deemed acceptable for the purposes of emissions reporting.
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7. QA/QC Requirements
Facilities should conduct quality assurance and quality control of the production and
consumption data, and emission estimates reported. Facilities are encouraged to prepare an in-
depth quality assurance and quality control plan which would include checks on production
data, the carbon content information received from the lab analysis, and calculations performed
to estimate GHG emissions.
7.1 Stationary Emissions
Facilities should follow the guidelines given for stationary combustion in EPA-HQ-OAR-
2008-0508-004.
7.2 Process Emissions
Options and considerations for QA/QC will vary depending on the proposed monitoring
method. Each option would require unique QA/QC measures appropriate to the particular
methodology employed to ensure proper emission monitoring and reporting.
7.2.1 Continuous Emission Monitoring System (CEMS)
For units using CEMS to measure N2O flow rates or N2O emissions, the equipment should be
tested for accuracy and calibrated as necessary by a certified third party vendor. These
procedures should be consistent in stringency and data reporting and documentation adequacy
with the QA/QC procedures for CEMS described in Part 75 of the Acid Rain Program.
7.2.2 Stack Test Data
U.S. EPA regulations for performance testing under 40 CFR § 63.7(c)(2)(i) state that before
conducting a required performance test, the owner/operator is required to develop a site-
specific test plan and, if required, submit the test plan for approval. The test plan is required to
include "a test program summary, the test schedule, data quality objectives, and both an
internal and external quality assurance (QA) program" to be applied to the stack test. Data
quality objectives are defined under 40 CFR § 63.7(c)(2)(i) as "the pre-test expectations of
precision, accuracy, and completeness of data." Under 40 CFR § 63.7(c)(2)(ii), the internal
QA program is required to include, "at a minimum, the activities planned by routine operators
and analysts to provide an assessment of test data precision; an example of internal QA is the
sampling and analysis of replicate samples." Under 40 CFR § 63.7(c)(2)(iii) the external QA
program is required to include, "at a minimum, application of plans for a test method
performance audit (PA) during the performance test." In addition, according to the 2005
Guidance Document, a site-specific test plan should generally include chain of custody
documentation from sample collection through laboratory analysis including transport, and
should recognize special sample transport, handling, and analysis instructions necessary for
each set of field samples (US EPA 2005).
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
7.3 Data Management
Data management procedures should be included in the QA/QC Plan. Elements of the data
management procedures plan are as follows:
• Check for temporal consistency in production data and emission estimates. If outliers
exist, they should be explained by changes in the facility's operations or other factors.
A monitoring error is probable if differences cannot be explained by changes in activity
levels, changes concerning fuels or input material, or changes concerning the emitting
process (e.g. energy efficiency improvements) (European Commission 2007).
• Determine the "reasonableness" of the emission estimate by comparing it to previous
year's estimates and relative to national emission estimate for the industry:
o Comparison of data on fuel or input material consumed by specific sources with
fuel or input material purchasing data and data on stock changes,
o Comparison of fuel or input material consumption data with fuel or input material
purchasing data and data on stock changes,
o Comparison of emission factors that have been calculated or obtained from the
fuel or input material supplier, to national or international reference emission
factors of comparable fuels or input materials
o Comparison of emission factors based on fuel analyses to national or international
reference emission factors of comparable fuels, or input materials,
o Comparison of measured and calculated emissions (European Commission 2007).
• Maintain data documentation, including comprehensive documentation of data received
through personal communication.
• Check that changes in data or methodology are documented.
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Technical Support Document for Adipic Acid: Proposed Rule for Mandatory Reporting of Greenhouse Gases
8. Types of Emission Information to be Reported
8.1 Types of Emissions to be Reported
Adipic acid facilities should report both process (N2O) and combustion related (CO2, CH4, and
N2O) greenhouse gas emissions. The data to be reported may very depending on monitoring
options selected. However, an adipic acid facility should report the number of adipic acid
production lines, annual adipic acid production, annual adipic acid production capacity,
electricity usage (kilowatt-hours), emission factor(s) used, abatement technology used (if
applicable), abatement utilization factor (percent of time that abatement system is operating),
abatement technology efficiency, and annual operating hours. For reporting options for
stationary combustion refer to EPA-HQ-OAR-2008-0508-004.
8.2 Other Information to be Reported
Other information to be reported will vary depending on selected option. For verification and
checks of reasonableness facilities should also report their annual adipic acid production,
abatement system uptime and percent of total operational hours/year (i.e. the fraction of
operational hours where the abatement system is in use at the plant); abatement system
downtime and percent of total operational hours per year (i.e. the fraction of operational hours
where the abatement system is NOT in use and the abatement system is bypassed); and, the
destruction factor for each relevant abatement system.
8.3 Additional Data to be Retained Onsite
Facilities should be required to retain data concerning monitoring of GHG emissions onsite for
a period of at least five years from the reporting year. For CEMS these data would include
CEMS monitoring system data including continuous-monitored GHG concentrations and stack
gas flow rates, calibration and quality assurance records. For stack testing these data would
include stack test reports and associated sampling and chemical analytical data for the stack
test. Process data including process raw material and product feed rates and carbon contents
should also be retained on site for a period of at least five years from the reporting year. EPA
could use such data to conduct trend analyses and potentially to develop process or activity-
specific emission factors for the process.
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9. References
CEMS Cost Model. CEMS.XLS. Accessed on April 30, 2008. Available at:
http://www.epa.gov/ttn/emc/cem.html.
Childs, D. (2002) Personal communication. Dave Childs, DuPont, USA and Laxmi Palreddy,
ICF International. August 8, 2002.
Childs, D. (2003) Personal communication. Dave Childs, DuPont, USA and Duncan
Rotherham, ICF International. August 7, 2003.
CW (2007) "Product Focus: Adipic Acid." Chemical Week. August 1-8, 2007.
EPA (2008). "Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006". April
2008. EPA Document Number 430-R-08-005. Accessed on May 7, 2008. Available at:
http://www.epa.gov/climatechange/emissions/usinventorvreport.html.
ICIS (2007) "Adipic Acid." ICIS Chemical Business Americas. July 9, 2007.
IPCC (2006). Intergovernmental Panel on Climate Change. 2006 IPCC Guidelines for
National Greenhouse Gas Inventories. (See Chapter 3.4 - Adipic Acid).
Thiemens, M.H., and W.C. Trogler (1991) "Nylon production; an unknown source of
atmospheric nitrous oxide." Science 251:932-934.
USDOE (2007). Technical Guidelines Voluntary Reporting of Greenhouse Gases (1605(b))
Program. Office of Policy and International Affairs United States Department of Energy
(USDOE). January 2007. Accessed on April 30, 2008. Available at:
www.eia.doe. gov/oiaf/1605/Januarv2007_1605bTechnicalGuidelines.pdf.
U.S. EPA (2003) Part 75, Appendix Bl, Available at
http ://www. epa. gov/ airmarkt/spm/rule/001000000B. htm.
WBCSD (2001). World Business Council for Sustainable Development. The Greenhouse Gas
Protocol - A corporate reporting and accounting standard. September 1, 2001. Accessed on
April 30, 2008. Available at: http://www.wbcsd.org/web/publications/ghg-protocol.pdf.
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