Document ID: EPA-HQ-OAR-2011-0028-0084
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2012-08-31T04:00Z

TECHNICAL SUPPORT FOR OTHER TECHNICAL ISSUES ADDRESSED IN REVISIONS TO SUBPART I       Office of Air and Radiation, U.S. Environmental Protection Agency
                                       
                                  August 2012
                                       

1. Introduction
This document presents technical support for the following proposed changes in subpart I, Electronics Manufacturing, of the Greenhouse Gas Reporting Program (GHGRP):
   * addressing situations where research and development (R&D) activities are integrated with regular facility production;
   * revising the definition of maximum substrate starts;
   * clarifying and revising the heel factor provisions; 
   * revising the nitrous oxide(N2O) default emission factor and clarifying N2O regulatory language; and 
   * revising the measurement equipment accuracy and precision requirements.
This document is based on information from Technical Support Document for Process Emissions from Electronics Manufacture (e.g., Micro-electro-mechanical systems, liquid crystal displays, photovoltaics, and semiconductors): Proposed Rule for Mandatory Reporting of Greenhouse Gases, Revised  -  November 2010 (hereafter, the November 2010 TSD, available in docket EPA-HQ-OAR-2009-0927).  It is also based on non-confidential materials submitted to the EPA by the Semiconductor Industry Association (SIA).
2. Integrated Production and Research and Development Processes
Per 40 CFR 98.2(a)(5), emissions resulting from research and development (R&D) activities are not considered to be part of any source category under the GHGRP. However, in its petition for reconsideration of subpart I, SIA raised the issue that for some electronics manufacturing facilities (particularly semiconductor facilities) R&D operations are integrated with regular manufacturing operations to better evaluate process manufacturability (SIA, 2011). Accordingly, SIA suggested that it would be burdensome on facilities that have integrated R&D activities to segregate R&D emissions from process emissions that are required to be reported. While the provisions in subpart A make it clear that reporting R&D emissions is not required, this does not preclude facilities that have integrated R&D activities to report those R&D emissions as part of regular facility manufacturing emissions. Since this is a important issue for subpart I, the EPA is proposing that subpart I facilities that include R&D emissions in their report (1) specify this in their report and (2) provide an estimated percent, on a carbon dioxide equivalent (CO2e) basis, of annual emissions that are attributable to R&D activities. To provide flexibility and ease burden on reporters, the EPA is not specifying the methods facilities must use to estimate the percent of R&D emissions; however, the EPA is proposing that facilities maintain records of the calculation of the percent of total emissions of F-GHG and N2O attributable to R&D activities. These provisions would reduce burden on reporters with integrated R&D activities while still collecting information that will allow the EPA to compare non-R&D emissions across industries within the GHGRP.
3. Calculating Annual Manufacturing Capacity and Applicability Determinations
In the December 2010 version of subpart I (75 FR 74774) EPA finalized a definition of maximum designed substrate starts that read as follows: 
      Maximum designed substrate starts means the maximum quantity of substrates, expressed as surface area, that could be started each month during a reporting year if the facility were fully equipped as defined in the facility design specifications and if the equipment were fully utilized. It denotes 100 percent of annual manufacturing capacity of a facility.
Maximum designed substrate starts is used as the basis for determining a facility's annual manufacturing capacity in Equation I-5, and annual manufacturing capacity is subsequently used in subpart I threshold applicability determinations.
In its Petition for Reconsideration of subpart I, SIA noted however that, "The maximum capacity calculation, as set forth in the Final Subpart I, rests on two assumptions: (1) a facility has a full complement of equipment that corresponds to its design; and (2) this full complement of equipment is utilized to a maximum degree. Due to many factors, including ramping of production (both up and down) to meet market demand and retooling for new products, these assumptions do not reflect reality at most facilities most of the time." (SIA, 2011) In some cases, this may result in a facility triggering the reporting threshold in subpart I even though the actual capacity of the facility would not reach the estimated annual manufacturing capacity of the facility based on maximum designed substrate starts and calculated per the provisions in subpart I.
To better reflect a facility's actual potential to emit (on which threshold applicability calculations are based, see the November 2010 TSD), the EPA is proposing to amend the definition of "maximum designed substrate starts" so that it reflects the equipped capacity of the facility based on the equipment actually available for production and not on the designed capacity. The EPA is also proposing to revise the defined term to read "maximum substrate starts" to reflect the concept that annual capacity of a facility would no longer be based on the facility design, but actual installed capacity. The EPA is proposing to define "maximum substrate starts" as: 
   The maximum quantity of substrates, expressed as surface area, that could be started each month during a reporting year based on the equipment installed in that facility and assuming that the installed equipment were fully utilized. Manufacturing equipment is considered installed when it is on the manufacturing floor and connected to required utilities.
4. Facility-Wide Gas-Specific Heel Factor Provisions
The December 2010 subpart I required facilities to re-calculate a facility-wide gas-specific heel factor if they use a trigger point for change out for a gas and container type that differs by more than five percent from the previously used trigger point for change out for that gas and container type. In its Petition for Reconsideration, SIA raised the following issue with regard to this requirement: "While this requirement seems reasonable on its face, adhering to the technical specifications of this requirement in practice raises compliance difficulties. For example, under this requirement, if the trigger point used by a facility for a 20-pound container is two pounds, then any change in that trigger point of more than 0.1 pounds would require a facility to `recalculate a facility-wide gas-specific heel factor,'..." (SIA, 2011) SIA further noted that such a small change may represent process adjustments made to ensure that high yields of products are maintained, or may represent minor trigger point variations that are inherent when dealing with small quantities of gas. 
After considering this issue, the EPA has concluded that the intent of the provisions for recalculation of heel factors in subpart I in the December 2010 rule should be clarified. Therefore, the EPA is proposing an amendment to clarify the requirements in subpart I to state that a facility needs to recalculate a facility-wide gas-specific heel factor only if the facility executes a process change to modify the trigger point for a gas and container type that differs by more than five percent from the previously used trigger point for change out for that gas and container type. This amendment would clarify that variation in the actual heel left in gas containers would not result in a facility being required to recalculate heel factors. Recalculation of heel factors is needed only when there is an intentional change in the trigger point to reflect a process change at the facility.
SIA raised a similar measurement issue to the one described above for "small" gas containers with respect to the exceptional circumstance provisions in subpart I. The EPA included provisions in the December 2010 version of subpart I to account for situations or "exceptional circumstances" where gas containers are changed out at a point that deviates substantially from the a trigger point set for a given container. These exceptional circumstance provisions are intended to ensure that gas consumption is properly accounted for in these cases when estimating emissions. If an exceptional circumstance were to occur, subpart I requires that the amount of gas used for that container be manually measured (e.g., with a scale, pressure gauge, etc...) instead of relying on the heel factor for that gas and container type. EPA set the exceptional circumstance threshold at 20 percent or more than the set trigger point for change out for a container.
In its petition, SIA noted that the 20 percent limit presents difficulties when tracking exceptional circumstances for small containers because of the small quantities of gas that would be represented by an exceptional circumstance and that would have to be tracked. This comment prompted EPA to re-evaluate the exceptional circumstances threshold. 
In looking at Table 1, which presents gas container data provided by SIA, it can be seen that the range in sizes of gas containers used in the semiconductor manufacturing industry is quite broad. In deciding how to define a small container the EPA took into account an example from SIA examining containers of 20 pounds (approximately 9.08 kg) (SIA, 2011). The EPA also concluded there was a logical break in the gas container size data at 20 pounds (approximately 9.08 kg) (see gray highlighted row in Table 1). The EPA then evaluated how the 20 pounds or less small gas containers criteria would impact the minimum quantity of gas that would be required to be tracked manually in the case of exceptional circumstances. 
The EPA evaluated three alternative exceptional circumstance thresholds (25 percent, 50 percent, and 75 percent) to determine how an alternative threshold would translate into minimum gas quantities (kg) that would have to be manually tracked. It can be seen in moving from the current 20 percent threshold to a 25 percent threshold does not change the quantity of gas for small containers that would have to be tracked manually significantly, or at all in some cases. In moving to a 50 percent from a 20 percent there are substantial changes in the quantity of gas associated with the exceptional circumstance threshold; in many cases double the quantity of gas. The quantities seen under the 50 percent column for small gas containers (above the gray line) are also similar to many quantities seen for large gas containers under the 20 percent column (under the gray line). Moving to a 75 percent exceptional circumstance threshold for small containers results in a much larger rise in the gas quantity associated with the exceptional circumstance threshold, mostly resulting in quantities that are bigger than those seen for some large gas containers at the 20 percent threshold (below the gray line). In light of this analysis the EPA is proposing to define an exceptional circumstance for small gas containers, defined as 9.08 kg (20 pounds) or less, as a 50 percent deviation from the trigger point for container change out. This proposed threshold would provide a balance between the feasibility and burden associated with tracking exceptional circumstances, taking into account normal variation in day-to-day container management that would be more likely to trigger an exceptional circumstance, while providing EPA with accurate gas usage information. For larger containers, the EPA is proposing to maintain the 20 percent exceptional circumstance threshold currently in subpart I.
          Table 1. Analysis of Exceptional Circumstances (SIA, 2012a)
                                      Gas
                            Full Weight of Gas (kg)
                                 Heel Fraction
                               Heel Weight (kg)
                             Used Gas Weight (kg)
  Mass of Gas (kg) Reflected at Different Exceptional Circumstance Thresholds
                                       
                                       
                                       
                                       
                                       
                 20 Percent Exceptional Circumstance Threshold
                 25 Percent Exceptional Circumstance Threshold
                 50 Percent Exceptional Circumstance Threshold
                 75 Percent Exceptional Circumstance Threshold
                                      CF4
                                     0.82
                                     5.00%
                                     0.04
                                     0.78
                                     0.01
                                     0.01
                                     0.02
                                     0.03
                                     CH3F
                                     1.36
                                    21.00%
                                     0.29
                                     1.08
                                     0.06
                                     0.07
                                     0.14
                                     0.21
                                     C4F6
                                     2.72
                                     7.00%
                                     0.19
                                     2.53
                                     0.04
                                     0.05
                                     0.10
                                     0.14
                                     CH2F2
                                     3.18
                                    20.00%
                                     0.64
                                     2.54
                                     0.13
                                     0.16
                                     0.32
                                     0.48
                                     CH2F2
                                     4.54
                                    20.00%
                                     0.91
                                     3.63
                                     0.18
                                     0.23
                                     0.45
                                     0.68
                                     CH3F
                                     4.54
                                    21.00%
                                     0.95
                                     3.58
                                     0.19
                                     0.24
                                     0.48
                                     0.71
                                     CH3F
                                     6.80
                                    13.00%
                                     0.88
                                     5.92
                                     0.18
                                     0.22
                                     0.44
                                     0.66
                                     CHF3
                                     6.80
                                     5.00%
                                     0.34
                                     6.46
                                     0.07
                                     0.09
                                     0.17
                                     0.26
                                     C4F8
                                     6.94
                                    10.00%
                                     0.69
                                     6.25
                                     0.14
                                     0.17
                                     0.35
                                     0.52
                                     CH3F
                                     8.62
                                    10.00%
                                     0.86
                                     7.76
                                     0.17
                                     0.22
                                     0.43
                                     0.65
                                     C5F8
                                     8.98
                                    10.00%
                                     0.90
                                     8.08
                                     0.18
                                     0.22
                                     0.45
                                     0.67
                                      CF4
                                     18.14
                                     5.00%
                                     0.91
                                     17.24
                                     0.18 
                                     0.23
                                     0.45
                                     0.68
                                      SF6
                                     18.14
                                     6.00%
                                     1.09
                                     17.06
                                     0.22 
                                     0.27
                                     0.54
                                     0.82
                                     C4F8
                                     19.96
                                    10.00%
                                     2.00
                                     17.96
                                     0.40 
                                     0.50
                                     1.00
                                     1.50
                                     CHF3
                                     21.32
                                    11.10%
                                     2.37
                                     18.95
                                     0.47 
                                     0.59
                                     1.18
                                     1.77
                                     CHF3
                                     21.32
                                    11.10%
                                     2.37
                                     18.95
                                     0.47 
                                     0.59
                                     1.18
                                     1.77
                                      NF3
                                     21.77
                                     5.00%
                                     1.09
                                     20.68
                                     0.22 
                                     0.27
                                     0.54
                                     0.82
                                      NF3
                                     21.77
                                     5.00%
                                     1.09
                                     20.68
                                     0.22 
                                     0.27
                                     0.54
                                     0.82
                                     C4F8
                                     22.68
                                    10.00%
                                     2.27
                                     20.41
                                     0.45 
                                     0.57
                                     1.13
                                     1.70
                                      NF3
                                     22.68
                                     5.00%
                                     1.13
                                     21.55
                                     0.23 
                                     0.28
                                     0.57
                                     0.85
                                      NF3
                                     22.68
                                     4.00%
                                     0.91
                                     21.77
                                     0.18 
                                     0.23
                                     0.45
                                     0.68
                                     C4F8
                                     23.13
                                    10.00%
                                     2.31
                                     20.82
                                     0.46 
                                     0.58
                                     1.16
                                     1.73
                                     C4F8
                                     31.75
                                     7.00%
                                     2.22
                                     29.53
                                     0.44 
                                     0.56
                                     1.11
                                     1.67
                                     C4F8
                                     31.75
                                     5.00%
                                     1.59
                                     30.16
                                     0.32 
                                     0.40
                                     0.79
                                     1.19
                                      CF4
                                     31.75
                                     5.00%
                                     1.59
                                     30.16
                                     0.32 
                                     0.40
                                     0.79
                                     1.19
                                      CF4
                                     31.75
                                     5.00%
                                     1.59
                                     30.16
                                     0.32 
                                     0.40
                                     0.79
                                     1.19
                                     CH2F2
                                     31.75
                                     2.90%
                                     0.92
                                     30.83
                                     0.18 
                                     0.23
                                     0.46
                                     0.69
                                     CHF3
                                     34.02
                                    14.00%
                                     4.76
                                     29.26
                                     0.95 
                                     1.19
                                     2.38
                                     3.57
                                     C2F6
                                     43.09
                                     6.00%
                                     2.59
                                     40.51
                                     0.52 
                                     0.65
                                     1.29
                                     1.94
                                      SF6
                                     43.09
                                     6.00%
                                     2.59
                                     40.51
                                     0.52 
                                     0.65
                                     1.29
                                     1.94
                                     C2F6
                                     45.36
                                     5.00%
                                     2.27
                                     43.09
                                     0.45 
                                     0.57
                                     1.13
                                     1.70
                                      SF6
                                     45.36
                                     5.00%
                                     2.27
                                     43.09
                                     0.45 
                                     0.57
                                     1.13
                                     1.70
                                      SF6
                                     45.36
                                    10.00%
                                     4.54
                                     40.82
                                     0.91 
                                     1.13
                                     2.27
                                     3.40
                                      SF6
                                     45.36
                                     6.00%
                                     2.72
                                     42.64
                                     0.54 
                                     0.68
                                     1.36
                                     2.04
                                      SF6
                                     45.36
                                     5.00%
                                     2.27
                                     43.09
                                     0.45 
                                     0.57
                                     1.13
                                     1.70
                                     C3F8
                                     47.63
                                     9.50%
                                     4.52
                                     43.10
                                     0.90 
                                     1.13
                                     2.26
                                     3.39
                                     C4F8
                                     49.58
                                     2.00%
                                     0.99
                                     48.59
                                     0.20 
                                     0.25
                                     0.50
                                     0.74
                                      NF3
                                    219.99
                                     4.00%
                                     8.80
                                    211.19
                                     1.76 
                                     2.20
                                     4.40
                                     6.60
                                      CF4
                                    260.82
                                     5.00%
                                     13.04
                                    247.77
                                     2.61 
                                     3.26
                                     6.52
                                     9.78
                                      CF4
                                    326.59
                                     5.00%
                                     16.33
                                    310.26
                                     3.27 
                                     4.08
                                     8.16
                                     12.25
                                     CHF3
                                    362.87
                                     5.00%
                                     18.14
                                    344.73
                                     3.63 
                                     4.54
                                     9.07
                                     13.61
                                      NF3
                                    362.87
                                     1.90%
                                     6.89
                                    355.98
                                     1.38 
                                     1.72
                                     3.45
                                     5.17
                                     C2F6
                                    430.91
                                     6.00%
                                     25.85
                                    405.06
                                     5.17 
                                     6.46
                                     12.93
                                     19.39
                                      NF3
                                    498.95
                                    10.00%
                                     49.90
                                    449.06
                                     9.98 
                                     12.47
                                     24.95
                                     37.42
                                     C4F8
                                    544.31
                                     2.00%
                                     10.89
                                    533.42
                                     2.18 
                                     2.72
                                     5.44
                                     8.16

5. Estimating N2O Emissions
The EPA is proposing two amendments to the provisions for estimating N2O emissions from electronics manufacturing. The first is to clarify the intent of the provisions, and the second is to revise the default emission factor (EF) for N2O emissions from all processes other than chemical vapor deposition (CVD).
The EPA is proposing to revise the language in subpart I to clarify that the intent of the December 2010 final rule is to require facilities to estimate only two distinct types of N2O emissions (i.e., two N2O emissions numbers). These are (1) the aggregate of N2O emissions resulting from chemical vapor deposition (CVD) processes and (2) the aggregate of N2O emissions resulting from all other N2O-using processes at an electronics manufacturing facility. This clarification is being proposed in response to questions raised in SIA's petition about EPA's intent in the December 2010 final rule because of minor differences in wording in the rule sections for calculating and reporting emissions. These differences made the requirement ambiguous about whether reporting is for each kind of process or all processes combined.
Second, the EPA is proposing to revise the default emission factor provided in Table I-8 to subpart I representing non-CVD N2O-using processes in light of new emission data and information submitted as a result of investigating and developing the proposed stack testing option. N2O stack test data indicated that the N2O emission factors for a fab may be above 1.0 (for all processes). Table 2 below presents the emission factor data collected through stack testing from two companies.
                  Table 2. N2O Emission Factors (SIA, 2012b)
Company/Fab
Available N2O EFs
Average Fab N2O EFs
Company F Fab1
                                     0.87
                                     1.15

                                      1.7
                                       

                                     1.89
                                       

                                     0.77
                                       

                                     1.15
                                       

                                     0.54
                                       
Company F Fab 2
                                     1.76
                                     1.76
Company D
                                     0.34
                                     0.50

                                     0.66

Average Across All Three Fabs
                                     1.14
            Note: N2O data from Company F, Fab 1 for the years 2003 to 2005 were not used because 
            it was reported to EPA that these EFs were based on incorrectly recorded N2O usage data. 
            These data are not reflected in table above. (SIA, 2012c)
The EPA and SIA could not identify the cause of the N2O emission factors reported in Table 2 that are greater than 1.0 (SIA, 2012c). N2O is not generally known to be a by-product from processes used in electronics manufacturing; however, the data presented in Table 2 indicate that there may be a physical or chemical process that results  in N2O being formed. Therefore, the EPA is proposing to revise the default N2O emission factor for the aggregate of other N2O-using processes to be 1.14, based on the average of the data in Table 2. The EPA is not proposing to revise the default N2O EF for CVD processes because EPA has historical data supporting this EF (see the November 2010 TSD for a discussion of this data and setting the N2O CVD default EF) and no new data are available indicating this EF should be revised. 

6. Accuracy and Precision of Measurement Equipment
The EPA is proposing to revise the accuracy and precision requirements for measurement equipment at 40 CFR 98.94(i). The December 2010 version of subpart I has a requirement that all measurement equipment (e.g., flow meters, weigh scales, pressure gauges, and thermometers) have an accuracy and precision of one percent of full scale or better. In light of new information submitted by SIA in its petition (SIA, 2011) and in response to questions from the EPA, the EPA is proposing to revise the accuracy and precision requirements of subpart I to 1) remove the subpart-specific requirements and 2) reference the general calibration and accuracy requirements in subpart A (see 40 CFR 98.3(i)). The EPA is proposing this modification because although the majority of new facilities and new equipment will be able to meet the one percent of full scale accuracy requirement, many older facilities have accuracies of two to four percent (SIA, 2011). Modifying the requirements would reduce the burden for facilities that would otherwise have to make capital investments to upgrade measurement equipment to meet the one percent of full scale provision. This provision modification is not expected to impact the accuracy of facility GHG emission estimates at facilities that are using measurement equipment that met the one percent of full scale standard. It may impact the accuracy of F-GHG emission estimates, particularly at older facilities that have less accurate measurement equipment.  The accuracy requirements in subpart A that EPA is proposing to apply to subpart I are a minimum requirement. Facilities that are currently meeting the higher accuracy standard in subpart I would be expected to continue to use the same monitoring equipment and achieve the same level of accuracy, and would not be expected to "fall back" to the minimum accuracy requirement in subpart A by, for example, replacing current equipment with less accurate monitoring equipment. Additionally, as older facilities and equipment are replaced and newer facilities come online, the industry is expected to trend towards using more accurate and precise measurement equipment.
7. References
SIA (2011). Semiconductor Industry Associated Petition for Reconsideration and Request for Stay Pending Reconsideration of Subpart I of the Final Rule for Mandatory Reporting of Greenhouse Gases. January 31, 2011. Available in docket EPA - HQ - OAR - 2011-0028.
SIA (2012a). Appendix 4 - Gas Cylinder Heel Triggers Industry. February 6, 2012.  Available in docket EPA - HQ - OAR - 2011-0028.
SIA (2012b). Response to EPA's Stack Test Question 1. March 7, 2012. Available in docket EPA - HQ - OAR - 2011-0028.
SIA (2012c). Outstanding Questions / Topics from SIA / EPA Discussions as of April 24, 2012 Response as of April 26, 2012. April 26, 2012. Available in docket EPA - HQ - OAR - 2011-0028.