Document ID: EPA-HQ-OAR-2019-0424-0278
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2023-05-22T04:00Z

TECHNICAL SUPPORT DOCUMENT ON USE OF FLUORINATED HEAT TRANSFER FLUIDS OUTSIDE OF THE ELECTRONICS INDUSTRY: SUPPLEMENTAL PROPOSED RULE FOR THE GREENHOUSE GAS REPORTING PROGRAM
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                                    Office of Air and Radiation
                                           U.S. Environmental Protection Agency
                                                                               
                                                                               
                                                                    May 2, 2023
                                   CONTENTS
                                       
1. Introduction	1
2.  Comparison Between Reported Supplies and Emissions of F-HTFs	1
2.1  F-HTFs and quantities aggregated	1
2.2  Findings and analysis	3
3.  References	4

1. Introduction  

During electronics manufacturing, fluorinated heat transfer fluids (F-HTFs) are used for temperature control, device testing, cleaning substrate surfaces and other parts, and soldering.  Outside of electronics manufacturing, F- HTFs are used for additional applications such as solvent applications, cooling of electronics for military purposes, aerospace applications, immersion cooling (e.g., to cool computers in data centers), cooling during manufacturing of pharmaceuticals, and other medical applications (3M, 2022 and Solvay, 2022). Fluorinated compounds used as F-HTFs include, but are not limited to, perfluoropolyethers (including perfluoropolymethylisopropyl ethers or PFPMIEs), perfluoroalkylamines, perfluoroalkylmorpholines, perfluoroalkanes,  certain hydrofluorocarbons, and hydrofluoroethers. Many of these compounds have global warming potentials (GWPs) near 10,000 and atmospheric lifetimes near 1,000 years. While F-HTFs are liquid at room temperature, they enter the atmosphere through evaporation, especially since they are used at elevated temperatures. Due to these chemical and physical properties, F-HTFs have represented 11 to 16 percent of GWP-weighted U.S. emissions from electronics manufacturing over the past 11 years, with total annual emissions ranging between 600,000 and 900,000 mtCO2e.

2.  Comparison Between Reported Supplies and Emissions of F-HTFs

Currently, electronics manufacturers reporting under the Greenhouse Gas Reporting Program (GHGRP) are required to report their emissions of F-HTFs. Suppliers of F-HTFs that exceed applicable thresholds are required to report the quantities of F-HTFs that they supply. Electronics manufacturers calculate their F-HTF emissions using a method that accounts for purchases, disbursements (including disbursements for destruction), changes in the nameplate capacity of manufacturing tool chillers, and changes in the quantities of F-HTFs in storage. However, they are not required to report these quantities to the EPA. Similarly, F-HTF suppliers are not required to report the uses for which F-HTFs are sold or the quantities sold for those uses.

To better understand the share of F-HTF supplies that are sold to replace F-HTFs that are emitted from electronics, the EPA compared aggregated F-HTF supplies to emissions of the same F-HTFs for 2010, 2020, and 2021. Because supplies of individual F-HTFs from individual suppliers have been determined to be confidential business information (CBI), supplies were aggregated across multiple F-HTFs and suppliers. Only the aggregated quantities that passed the GHGRP's CBI aggregation criteria (as described in 79 FR 32948, June 9, 2014) are shown below. 

2.1  F-HTFs and quantities aggregated

In general, estimates of supplies should account for both additions to and subtractions from the supply and for the compounds that make up most of the supply. The totals shown below in Table 1 are the aggregated net supply, in tons of CO2-equivalent, of compounds used as fluorinated heat transfer fluids and reported under subpart OO, Suppliers of Industrial Greenhouse Gases, except for hydrofluoroethers (HFEs), sulfur hexafluoride (SF6), and perfluorocarbons (PFCs) and hydrofluorocarbons (HFCs) that are gaseous at standard temperature and pressure (i.e., at 20 °C and an absolute pressure of 1 atm or 101.325 kPa). This is the GWP-weighted sum across compounds of the U.S. net supplies of perfluorotripropylamine, perfluorotributylamine, perfluorotripentylamine, perfluoromethylmorpholine, perfluoroisopropylmorpholine, 2,2,3,3,5,5,6,6-Octafluoro-4-(heptafluoropropyl)morpholine, perfluoropolymethylisopropyl ethers (PFPMIEs), perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, and HFC-43-10mee.  The net supply is defined as the quantity produced + quantity imported  -  quantity exported  -  quantity transformed  -  quantity destroyed. Both emissions and supplies were weighted by the current chemical-specific and default GWPs in Table A-1 to subpart A to part 98.

HFEs were excluded from the total because the calculated net supplies of HFEs were persistently negative year after year, which implies either that there was a reporting error by one or more facilities or that the data collected by the GHGRP for HFEs are somehow biased (for example, because the U.S. supply is significantly affected by importers, but not exporters, that fall below the GHGRP reporting threshold). In recent years, HFEs have accounted for approximately 1% of total GWP-weighted F-HTF emissions from electronics manufacturing, which implies that the actual supplies may be similarly small, but it is possible that there are significant uses of HFE F-HTFs outside of electronics manufacturing.  

F-HTF production facilities are required to report the quantities of F-HTFs that they produce, import, export, transform, destroy, and send offsite for destruction by another facility. One way to calculate the net supply is to add the quantities sent offsite for destruction to the total net supply. This assumes that these quantities will be reported as destroyed by the receiving facility and subsequently subtracted from the calculated net supply. F-HTF production facilities have always been required to report the quantities of fluorinated HTFs that they receive and destroy by chemical, and since 2018, free-standing destruction facilities have also been required to report the quantities of F-HTFs that they destroy by chemical.  However, over the time series, the quantities of F-HTFs reported by producers as being sent offsite for destruction have been significantly larger than the quantities reported by production and destruction facilities as being destroyed.  This implies that the destruction of these compounds is underreported, and the EPA is investigating this inconsistency. In the meantime, to minimize the bias that may be introduced by the inconsistency, we are excluding the quantities sent offsite for destruction from this analysis.  To the extent that the quantities reported as destroyed include amounts reported as being sent offsite for destruction, this approach will underestimate the net supply. Due to this and other uncertainties, the total net supplies are reported to one significant digit only.

U.S. emissions of perfluoroalkylmorpholines, perfluoroalkylamines, PFPMIEs, PFCs, and HFC-43-10-mee from F-HTF applications in electronics manufacturing were estimated by summing the emissions of these compounds reported under the GHGRP and scaling up the total to account for emissions from electronics manufacturing facilities that do not report to the GHGRP. The scale-up factor is based on the estimated annual production of non-reporting electronics facilities. Reported and estimated emissions are shown below in Table 1.
Table 1. Emissions of Certain F-HTFs from Electronics Manufacturing Reported to the GHGRP and Estimated for the U.S. (mtCO2e)

                                                                           2011
                                                                           2012
                                                                           2013
                                                                           2014
                                                                           2015
                                                                           2016
                                                                           2017
                                                                           2018
                                                                           2019
                                                                           2020
                                                                           2021
Perfluoroalkyl-morpholines
                                                                        138,512
                                                                        101,381
                                                                        102,730
                                                                        104,231
                                                                         79,701
                                                                         74,078
                                                                         51,146
                                                                         57,326
                                                                         55,208
                                                                         59,423
                                                                         52,276
Perfluorotrialkylamines
                                                                        389,866
                                                                        430,682
                                                                        284,022
                                                                        471,787
                                                                        429,017
                                                                        378,244
                                                                        375,550
                                                                        401,954
                                                                        355,561
                                                                        370,838
                                                                        351,477
PFPMIEs
                                                                        189,569
                                                                        206,626
                                                                        174,946
                                                                        175,289
                                                                        203,457
                                                                        169,880
                                                                        145,220
                                                                        179,088
                                                                        167,882
                                                                        146,384
                                                                        144,882
PFCs
                                                                          7,251
                                                                          9,882
                                                                          3,712
                                                                          1,584
                                                                          2,776
                                                                          2,591
                                                                          8,946
                                                                          9,797
                                                                          8,205
                                                                          7,569
                                                                          5,319
HFC-43-10mee
                                                                              -
                                                                              -
                                                                              -
                                                                              -
                                                                              0
                                                                              0
                                                                              0
                                                                              1
                                                                              2
                                                                              -
                                                                              1
Total reported
                                                                        725,197
                                                                        748,572
                                                                        565,409
                                                                        752,892
                                                                        714,952
                                                                        624,793
                                                                        580,862
                                                                        648,166
                                                                        586,859
                                                                        584,215
                                                                        553,956
Scale up to account for non-reporting facilities 
                                                                           1.05
                                                                           1.06
                                                                           1.04
                                                                           1.04
                                                                           1.02
                                                                           1.02
                                                                           1.02
                                                                           1.02
                                                                           1.02
                                                                           1.03
                                                                           1.02
Total including scale-up
                                                                        763,576
                                                                        793,255
                                                                        587,727
                                                                        782,610
                                                                        731,409
                                                                        638,698
                                                                        594,090
                                                                        662,244
                                                                        600,193
                                                                        599,275
                                                                        567,002
 

2.2  Findings and analysis

Table 2 shows the results of the comparison between the reported supplies and emissions of the F-HTFs listed above.  

Table 2. Comparison Between Reported Supplies of Certain F-HTFs and Emissions of Same F-HTFs Reported by Electronics Manufacturers (mtCO2e)
                                       
                                                                           2010
                                                                           2020
                                                                           2021
U.S. Net Supply of F-HTFs
                                                                      4,000,000
                                                                      5,000,000
                                                                      5,000,000
U.S. Emissions of F-HTFs from Electronics Manufacturing
                                                                       *763,576
                                                                        599,275
                                                                        567,002
Supplies/Emissions
                                                                              5
                                                                              8
                                                                              9
      *Emissions from 2011 are shown because emissions from electronics manufacturing were not reported in 2010.

In each year, the U.S. net supplies of the F-HTFs were between 5 and 9 times greater than the emissions of the same HTFs reported by the electronics industry. (The ratios were similar for years for which aggregated supplies did not pass the GHGRP's CBI aggregation criteria.) There are multiple potential explanations for this persistent difference. First, consumption within the electronics industry could be responsible for some of the difference if electronics manufacturers were adding new chiller nameplate capacity, stockpiling F-HTFs, and/or sending significant quantities of F-HTFs offsite for destruction or other purposes. As noted above, the electronics industry does not report nameplate capacities or F-HTF flows (other than emissions) under the GHGRP. However, the quantities of nameplate capacity added or F-HTFs stockpiled or disbursed would have to be several times larger than the quantities of F-HTFs emitted within the electronics industry in order to account for the full difference. This appears to be unlikely. Moreover, stockpiling is not likely to continue year after year, which would be required for it to account for the long-term differences observed. 

The second set of potential explanations for the difference includes reporting errors and potential biases introduced by GHGRP reporting thresholds. Importers, exporters, and free-standing destruction facilities are only required to report their imports, exports, or destruction if the total quantities of F-GHGs, F-HTFs, nitrous oxide, and CO2 that they import or export, or the total quantities of F-GHGs and F-HTFs that they destroy, exceed 25,000 mtCO2e per year. Due to the high GWPs of F-GHGs and F-HTFs, most of the quantities imported, exported, and destroyed are likely to be subject to GHGRP reporting requirements, but there may be exceptions. While it appears unlikely that thresholds would have a different impact on importers than on exporters, this possibility cannot be ruled out entirely. In addition, as discussed above, destruction of F-HTFs appears to be underreported, which is expected to lead to an overestimate of supplies. However, it is improbable the reporting biases and errors listed above account for the large, long-term difference between F-HTF emissions from electronics manufacturing and F-HTF supplies.  

The third set of potential explanations for the difference relates to uses of F-HTFs outside of the electronics industry. Based on conversations with F-HTF suppliers, uses of F- HTFs outside of the electronics industry include various solvent applications (deposition and cleaning), cooling of electronics for military purposes, aerospace applications, immersion cooling (e.g., to cool computers in data centers), cooling during manufacturing of pharmaceuticals, and other medical applications (3M, 2022 and Solvay, 2022). For certain F-HTFs, some of these applications, rather than electronics manufacturing, account for most U.S. consumption. These other applications therefore appear to drive much, and perhaps most, of the difference between the quantities of F-HTFs emitted by electronics manufacturers and the quantities of F-HTFs supplied by suppliers. Moreover, the fractions of the F-HTF supply that are used for the various applications are changing as F-HTF usage in certain applications, such as cooling for data centers, grows. Given the dynamic nature of this market, regular updates on the uses of F-HTFs and the quantities sold to each are important for understanding where and how these potent F-GHGs are used and emitted.

3.  References 

3M. Conference calls between Deborah Ottinger, US EPA, and John Owens and Il Ji Kim of 3M on March 21, 2022 and June 24, 2022.

Solvay. Conference call between Deborah Ottinger, US EPA, and Michael Blume and Antonella Di Meo, Solvay on March 25, 2022.