### R equest to Use an Alternate GWP for Carbonyl Fluoride (CAS Number: 353

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- 4 )

Summary:

EPA recently promulgated a mandatory reporting regulation for Fluorinated Greenhouse Gases ( F

- GHG). The regulation requires f acilities to monitor and report CO 2 - equiva lent F

- GHG process vent emissions, if those emissions exceed a threshold of 10,000 metric tons CO 2 - equivalent per year. [1] Estimated CO 2 - equivalent emissions are obtai ned by multiplying the F

- GHG mass emissions by the Global Warming Potential for the individual fluorinated gases that comprise the flow. EPA has provided a t able of 100

- year time horizon GWP values for about 70 individual F

- GHG

, and specifies that these

v alues are to be used for the purpose of computing CO 2 - equivalent emissions

. [2] A default GWP value of 2,000 is to be used for any F

- GHG not listed in Table A

- 1. T he regulation allows a facility to request a lower provisional GWP when clear scientific evidence exists t o support such a lower value.

Table A

– 1 does not list a GWP for carbonyl fluoride

. Carbonyl fluoride is a s hort

- lived fluorinated aldehyde . T he default GWP value of 2,000 is inappropriate for such gases and a substantial body of evidence in the peer

- rev iewed scientific literature has established that the GWP s of fluorinated aldehyde are modest

. T he atmospheric lifetime of carbonyl fluoride has been conservatively estimated as 7.1 days; the infrared spectrum of carbonyl fluoride has been accurately estim ated using ab initio quantum chemical methods recommended in the peer

- reviewed scientific literature and the GWP of carbonyl fluoride has been estimated as 2 relative to CO 2 with a 100

- year integration time horizon. DuPont is requesting a provisional GWP of 2 be assigned for carbonyl fluoride

. Evidence Supporting Request :

F

- GHG Identity : Carbonyl fluoride Chemical Formula : C O F 2 CAS Number: 353

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Estimated GWP: 2 relative to CO 2 with a 100

- year integration time horizon

Data and analysis: Kanakidou et al. estimated the global and yearly averaged atmospheric lifetime for carbonyl fluoride to lie in the range of 3.9 to 7.1 days by embedding experimentally determined Henry’s law coefficients and hydrolysis rate
constants into a global tropospheric ch em ical transport model. [3] We have used the most conservative atmospheric lifetime (7.1 days) in our analysis. I nfrared cross

- sections of carbonyl fluoride were obtained using ab initio quantum chemical methods recommended in the peer

- reviewed scienti fic literature. [4

- 5] R adiative forcing calculations were performed using the approximation method developed by Pinnock et al. [6] Using this approach, a GWP for carbonyl fluoride of 2 relative to CO 2 with a 100

- year integration time horizon was established.The methods used in determining this GWP value are essentially identical to those used for the values obtained for the gases listed in Table A

- 1: (1) the kinetic rate constants for reaction with critical atmospheric oxidants were measured and an atmospheric lifetime was determined; (2) the infrared absorption spectrum of the substance was measured ; and (3 ) the atmospheric lifetime and infrared absorption spectrum were incorporated into a radiative transfer model to estimate the contribution of the substance to greenhouse forcing.

Based on this publication in the peer

- reviewed literature , DuPont requests that a provisional GWP of 2 be assigned for carbonyl fluoride

.

1. "Mandatory Reporting of Greenhouse Gases: Additional Sources of Fluorinated GHGs; Final Rule" , Federal Register 75:230 (December 1, 2010) p.74774. 2. "Table A

- 1 to Subpa rt A of Part 98

— Global Warming Potentials" : Table A

- 1 in 40 CFR part 98, subpart A. 3. Kanakidou, M., F.J. Dentener, and P.J. Crutzen, A global three

- dimensional study of the fate of HCFCs and HFC

- 134a in the troposphere. Journal of Geophysical Research, 1 995. 100 (D9). 4. Blowers, P. and K. Hollingshead, Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH2F2 and Other Fluorinated Methyl Species Verified by Comparison to Experiment. The Journal of Physical Chemistry A, 2 009. 113 (20): p. 5942

- 5950. 5. Halls, M.D. and H.B. Schlegel, Comparison of the performance of local, gradient

- corrected, and hybrid density functional models in predicting infrared intensities. The Journal of Chemical Physics, 1998. 109 (24): p. 10587

- 1059 3. 6. Pinnock, S., et al., Radiative forcing of climate by hydrochlorofluorocarbons and hydrofluorocarbons. Journal of Geophysical Research, 1995. 100 (D11): p. 23227

- 23238.