Request to Use an Alternate GWP for

Carbonyl Fluoride (CAS Number: 353-50-4)

Summary:

EPA recently promulgated a mandatory reporting regulation for Fluorinated Greenhouse 

Gases (F-GHG). The regulation requires facilities to monitor and report CO2-equivalent 

F-GHG process vent emissions, if those emissions exceed a threshold of 10,000 metric 

tons CO2-equivalent per year. [1] Estimated CO2-equivalent emissions are obtained 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 table of 100-

year time horizon GWP values for about 70 individual F-GHG, and specifies that these 

values are to be used for the purpose of computing CO2-equivalent emissions. [2] A 

default GWP value of 2,000 is to be used for any F-GHG not listed in Table A-1. The 

regulation allows a facility to request a lower provisional GWP when clear scientific 

evidence exists to support such a lower value.

Table A–1 does not list a GWP for carbonyl fluoride. Carbonyl fluoride is a short-lived 

fluorinated aldehyde. The default GWP value of 2,000 is inappropriate for such gases 

and a substantial body of evidence in the peer-reviewed scientific literature has 

established that the GWPs of fluorinated aldehyde are modest. The atmospheric lifetime 

of carbonyl fluoride has been conservatively estimated as 7.1 days; the infrared spectrum 

of carbonyl fluoride has been accurately estimated 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 CO2 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: COF2

CAS Number: 353-50-4

Estimated GWP: 2 relative to CO2 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 chemical transport model. [3] We have used the 

most conservative atmospheric lifetime (7.1 days) in our analysis. Infrared cross-sections 

of carbonyl fluoride were obtained using ab initio quantum chemical methods 

recommended in the peer-reviewed scientific literature. [4-5] Radiative 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 CO2 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 Subpart 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, 1995. 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, 2009. 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. 10587-10593.

6. Pinnock, S., et al., Radiative forcing of climate by hydrochlorofluorocarbons and 

hydrofluorocarbons. Journal of Geophysical Research, 1995. 100(D11): p. 23227-

23238.