### R equest to Use an alternate GWP for Vinyl Fluoride (CAS Number: 75

- 02

- 5 )

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 - equivalent 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 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 t able of 100

- year time horizon GWP values for about 70 individual F

- GHG

, and specifies that these value s 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 to su pport such a lower value.

Table A

– 1 does not list a GWP for vinyl fluoride

. Vinyl fluoride is a s hort

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

- reviewed scient ific literature has established that the GWP s of fluorinated alkenes are modest . Kinetic rate constants for the atmospheric degradation of vinyl fluoride have been measured in an environmental chamber; the atmospheric lifetime of vinyl fluoride has been e stimated as 2 days; the infrared spectrum of vinyl fluoride has been accurately measured and the GWP of vinyl fluoride has been estimated as 0. 7 relative to CO 2 with a 100

- year integration time horizon. DuPont is requesting a provisional GWP of 0. 7 be ass igned for vinyl fluoride

. Evidence Supporting Request :

F

- GHG Identity : Vinyl fluoride Chemical Formula : C 2 H 3 F CAS Number: 75

- 02

- 5

Estimated GWP: 0. 7 relative to CO 2 with a 100

- year integration time horizon

Data and analysis: Baasandorj et al. have m easured kinetic rate constants for the vapor phase reaction of vinyl fluoride with OH. [3] T he global and yearly averaged lifetime of vinyl fluoride was calculated as 2 days. Quantitative infrared cross

- sections of vinyl fluoride were obtained at 298 K in the region 5 00

- 40 00 cm - 1 , and r adiative forcing calculat ions were performed using the approximation method developed by Pinnock et al.

. [4] A GWP of 0. 7 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 meas ured and an atmospheric lifetimewas 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 contrib ution of the substance to greenhouse forcing.

Based on this publication in the peer

- reviewed literature , DuPont requests that a provisional GWP of 0. 7 be assigned for vinyl fluoride

.

1. "Mandatory Reporting of Greenhouse Gases: Addit ional 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. Baasandorj, M., et al., Rate Coefficients for t he Gas

- Phase Reaction of the Hydroxyl Radical with CH2═CHF and CH2═CF2. The Journal of Physical Chemistry A, 2010. 114 (13): p. 4619

- 4633. 4. Pinnock, S., et al., Radiative forcing of climate by hydrochlorofluorocarbons and hydrofluorocarbons. Journal of Ge ophysical Research, 1995. 100 (D11): p. 23227

- 23238.