environmental impacts of the refrigerant r-1234yf...2013/12/04 · s. henne, et al.: environmental...

Dr. Stephan Henne

Empa, Abteilung Luftfremdstoffe/Umwelttechnik Dübendorf, Switzerland

Environmental Impacts of the Refrigerant R-1234yf

S. Henne, et al.: Environmental Impacts of R-1234yf PRO KLIMA, 2013-12-04 [email protected]

Environmental Impacts of Releases to the Atmosphere

Emitted Compounds

Atmosphere

Source: wikipedia


Air Quality


Stratospheric Ozone Depletion

Climate Change

Emitted Compounds

Atmosphere

Source: wikipedia


Air Quality



Climate Change

Emitted Compounds

Degradation Products

Photo- chemistry

Atmosphere

Source: wikipedia


Air Quality



Climate Change

Biosphere

Hydrosphere

Surface Deposition

Anthrosphere

Emitted Compounds

Degradation Products

Photo- chemistry

Atmosphere

Source: wikipedia


Source: Velders et al., Science (2012)

Source: IPCC 5th AR-WG1 (2013)

Radiative Forcing of Halogenated Hydrocarbons

~10% of all GHG

Halocarbons


HFC-134a versus HFO-1234yf

Worldwide most emitted HFC, mainly used in MACs: HFC-134a OH lifetime: 14.6 years 100-yr GWP: 1370

Current replacement HFO-1234yf

OH lifetime: 11 days 100-yr GWP: 4.4

Mobile Air Conditioning

(MAC)

HFC-134a (1,1,1,2-tetrafluoroethane)

HFO-1234yf (2,3,3,3-tetrafluoropropene)

Atmospheric abundance

Emissions


Global Warming Potential (GWP)

Determined by Atmospheric lifetime IR absorption cross sections

Atmospheric lifetimes of most HFOs limited due to double bond and reaction with OH radicals

Formula Name τOH (days) GWP100 CH2=CHF 2.2 0.7 CH2=CF2 4.1 0.9 CF2=CF2 HFO-1114 1.9 CH2=CHCF3 HFO-1243zf 7.6 CH2=CFCF3 HFO-1234yf 11 4 Z-CHF=CHCF3 HFO-1234ze(Z) 10 3 E-CHF=CHCF3 HFO-1234ze(E) 14 6 Z-CHF=CFCF3 HFO-1225ye(Z) 18 6 E-CHF=CFCF3 HFO-1225ye(E) 10 3 CF3CH=CF2 HFO-1225zc CHF2CF=CF2 HFO-1225yc CF2=CFCF3 HFO-1216 6 0.25 CH2=CHCF2CF3 8 (Z)-CF3CH=CHCF3 HFO-1336mzz 22 9 CF2=CFCF=CF2 1.9

Climate Change

R-1234yf


Global Warming Potential (GWP)

Determined by Atmospheric lifetime IR absorption cross sections

Atmospheric lifetimes of most HFOs limited due to double bond and reaction with OH radicals

Formula Name τOH (days) GWP100 CH2=CHF 2.2 0.7 CH2=CF2 4.1 0.9 CF2=CF2 HFO-1114 1.9 CH2=CHCF3 HFO-1243zf 7.6 CH2=CFCF3 HFO-1234yf 11 4 Z-CHF=CHCF3 HFO-1234ze(Z) 10 3 E-CHF=CHCF3 HFO-1234ze(E) 14 6 Z-CHF=CFCF3 HFO-1225ye(Z) 18 6 E-CHF=CFCF3 HFO-1225ye(E) 10 3 CF3CH=CF2 HFO-1225zc CHF2CF=CF2 HFO-1225yc CF2=CFCF3 HFO-1216 6 0.25 CH2=CHCF2CF3 8 (Z)-CF3CH=CHCF3 HFO-1336mzz 22 9 CF2=CFCF=CF2 1.9

Influence of HFOs on radiative forcing can be expected to be minor.

Climate Change

R-1234yf


As non-halogenated hydrocarbons HFOs can contribute to tropospheric ozone formation (summer smog)

Tropospheric Ozone Production from HFOs

Source: University of York, UK

Air Quality



POCP (Derwent et al., 1996) describes the potential of a molecule to contribute to O3 formation relative to ethene

Values comparable or smaller than those of the corresponding alkanes (Wallington et al., 2010, Atmos. Environ.)



Formula Name τOH (days) GWP100 POCP CH2=CHF 2.2 0.7 CH2=CF2 4.1 0.9 18 CF2=CF2 HFO-1114 1.9 12.5 CH2=CHCF3 HFO-1243zf 7.6 10.7 CH2=CFCF3 HFO-1234yf 11 4 7.0 Z-CHF=CHCF3 HFO-1234ze(Z) 10 3 E-CHF=CHCF3 HFO-1234ze(E) 14 6 6.4 Z-CHF=CFCF3 HFO-1225ye(Z) 18 6 5.6 E-CHF=CFCF3 HFO-1225ye(E) 10 3 7.3 CF3CH=CF2 HFO-1225zc CHF2CF=CF2 HFO-1225yc CF2=CFCF3 HFO-1216 6 0.25 5.4 CH2=CHCF2CF3 8 6.6 (Z)-CF3CH=CHCF3 HFO-1336mzz 22 9 3.4 CF2=CFCF=CF2 1.9

Air Quality

R-1234yf



POCP (Derwent et al., 1996) describes the potential of a molecule to contribute to O3 formation relative to ethene

Values comparable or smaller than those of the corresponding alkanes (Wallington et al., 2010, Atmos. Environ.)



Formula Name τOH (days) GWP100 POCP CH2=CHF 2.2 0.7 CH2=CF2 4.1 0.9 18 CF2=CF2 HFO-1114 1.9 12.5 CH2=CHCF3 HFO-1243zf 7.6 10.7 CH2=CFCF3 HFO-1234yf 11 4 7.0 Z-CHF=CHCF3 HFO-1234ze(Z) 10 3 E-CHF=CHCF3 HFO-1234ze(E) 14 6 6.4 Z-CHF=CFCF3 HFO-1225ye(Z) 18 6 5.6 E-CHF=CFCF3 HFO-1225ye(E) 10 3 7.3 CF3CH=CF2 HFO-1225zc CHF2CF=CF2 HFO-1225yc CF2=CFCF3 HFO-1216 6 0.25 5.4 CH2=CHCF2CF3 8 6.6 (Z)-CF3CH=CHCF3 HFO-1336mzz 22 9 3.4 CF2=CFCF=CF2 1.9

At expected HFO levels their contribution to tropospheric ozone production will be minor.

Air Quality

R-1234yf


Products of Atmospheric HFO Degradation

HFO-1234yf HFO-1234ze(E)



HFO-1234yf

Source: Hurley et al., 2008

HFO-1234ze(E)



HFO-1234yf


HFO-1234ze(E)

trifluoroacetyl fluoride (TFF)



HFO-1234yf


HFO-1234ze(E)

trifluoroacetyl fluoride (TFF)

trifluoroacetic acid (TFA)

100 % TFA yield

hydrolysis



HFO-1234yf

Source: Javadi et al., 2008

HFO-1234ze(E)



HFO-1234yf


HFO-1234ze(E)

trifluoroacetaldehyde



HFO-1234yf


HFO-1234ze(E)

trifluoroacetaldehyde photolysis

< 10 % TFA yield



HFO-1234yf


HFO-1234ze(E)

trifluoroacetaldehyde photolysis

< 10 % TFA yield

HFC-134a


Trifluoroacetic Acid (TFA)

Highly soluble; remains in aqueous phase No formation of insoluble salts

Phytotoxic (negative effect on plant growth) No observed effect concentration (NOEC) for most

sensitive freshwater algae: 120 µg/L Persistent under environmental conditions

Biodegradation not proven

Anthropogenic sources Atmospheric degradation of some HCFC and HFCs (e.g., HCFC-123,

-124; HFC-134a, -227ea) Thermolysis of fluoropolymers (e.g. Teflon) Atmospheric degradation of narcotics Minor: trifluoromethyl containing pesticides, aluminum production

Natural sources Underwater hydrothermal vents (?)


TFA in the Hydrosphere

Atmosphere (ppt) Europe: 0.005 – 0.02 South Africa: 0.008




Rainwater (µg/L) Europe: 0 – 1.5 Other: 0.02 – 0.8





Recent fresh water (lakes, springs rivers) Switzerland: ~100 (ng/L) US: 20 - 140 (ng/L) Vernal pools (US): 2-10 µg/L





Oceans (ng/L) down to 5 km: 150 – 200 South Pacific: 10-30 Possible source: hydrothermal vents







Ancient fresh water • Ground water • Ancient spring water • Ice cores No TFA detectable!







Ancient fresh water • Ground water • Ancient spring water • Ice cores No TFA detectable!


WMO Assessment of Ozone Depletion (2007) concluded: “TFA from the degradation of HCFCs and HFCs will not result in environmental concentrations capable of significant ecosystem damage.”


HFO-1234yf Atmospheric Simulations

Difference to present HFCs Larger yields Faster degradation Larger local TFA concentrations in rainwater expected Atmospheric chemistry and transport simulations of future HFO-1234yf Emission distribution Chemical mechanism Atmospheric transport

Aim: Assess complete year of TFA deposition

and rainwater concentrations in Europe

Henne et al., 2012, Environ. Sci. Technol.


HFO-1234yf Emission Inventory

Per MAC emission factors based on current HFC-134a results for Regular leaks (diffusive loss) Irregular leaks (accidental total

loss) Refilling Decommission

Annual loss: 36 - 63 g yr-1 MAC-1

Assuming completed adaption

until 2020 Predicted passenger car numbers

by country for 2020 (TREMOVE2.7b http://www.tremove.org/)

Spatial disaggregation following population and traffic distributions

High and low emission scenario 11.0 and 19.2 Gg yr-1 for EU27+

HFC-134a in 2006: ~25 Gg yr-1

(Stohl et al., 2009) 35 - 48.4 g yr-1 MAC-1 for USA

(Pappasavva et al., 2009)

http://www.tremove.org/


Annual Total TFA Deposition Rates

Limited inter-continental export of TFA

Grid box maxima: Europe: 2.5 kg/km2/yr Alps: 3.4 kg/km2/yr Prev. obs.: 0.05 – 0.2 kg/km2/yr


Annual Mean Rainwater Concentrations

EU mean: 0.58 µg/L

Local max: 1.7 – 2.2 µg/L Summer max: 6 µg/L Max. event: 13 µg/L

Prev. obs.: 0 – 1.5 µg/L TFA NOEC: 120 µg/L

Annual mean = Total wet deposition / total precipitation

Annual Mean

Summer Mean


Similar Results for a Study in the US

Luecken et al. (2010, Environ. Sci. Technol.)

Comprehensive, regional scale chemistry transport model with additional HFO-1234yf chemistry

Total Deposition (summer)

Rainwater Concentrations (summer)

Deposition Rates US mean: 0.48 kg/km2/yr US max: 2.34 kg/km2/yr

Rainwater concentrations US mean: 0.5 µg/L US max: 1.26 µg/L


Accumulation in Arid Regions and Landlocked Basins

Source: wikipedia


Accumulation in Landlocked Basins and Lakes

TFA accumulation in terminal water bodies in the US (Russell et al., 2012, Environ. Toxicol. Chem.)

Depostion rates from Lucken et al., 2010 NOEC only exceeded under most conservative scenario and

most extreme conditions (Sonoran Desert)

Source: Russell et al., 2012, Environ. Toxicol. Chem.


Accumulation in Landlocked Basins and Lakes

TFA accumulation in terminal water bodies in the US (Russell et al., 2012, Environ. Toxicol. Chem.)

Depostion rates from Lucken et al., 2010 NOEC only exceeded under most conservative scenario and

most extreme conditions (Sonoran Desert)

Source: Russell et al., 2012, Environ. Toxicol. Chem.

«[…] concentrations are not expected to have any observable adverse ecotoxicological impact […]» Periodic observations in terminal water bodies as early warning of TFA accumulation.


Tang et al., 2008: 100 Gg/yr of TFA for the next 100 years Oceanic increase of 7.4 ng/L

Final Accumulation in Oceans

Emissions 2008 (Gg/yr)

HFC-134a 150 HFC-23 12 HFC-152 50 HFC-143a 17 HFC-32 8.9 HFC-125 22 HFC-365mfc 3 HFC-227ea 1.8 Total 265

Source: WMO, 2010



More realistic: ocean mixing limited to upper 500 m within 100 years

Source: Gebbie and Huybers, 2012, J. Phys. Ocean.

Water Age by Depth Atlantic

Indian Ocean

Pacific




Source: WMO, 2010



More realistic: ocean mixing limited to upper 500 m within 100 years 150 – 300 Gg/yr of TFA



Indian Ocean

Pacific




Source: WMO, 2010



More realistic: ocean mixing limited to upper 500 m within 100 years 150 – 300 Gg/yr of TFA Ocean surface water

increase of 90 – 180 ng/L



Indian Ocean

Pacific




Source: WMO, 2010



More realistic: ocean mixing limited to upper 500 m within 100 years 150 – 300 Gg/yr of TFA Ocean surface water

increase of 90 – 180 ng/L



Indian Ocean

Pacific




Even in a worst case scenario TFA in ocean surface waters would only increase by a factor of 2 compared with current values (200 ng L-1). Far below NOEC (120 µg/L)!

Source: WMO, 2010


Conclusions

Atmospheric chemistry and fate of several HFOs including R-1234yf has been assessed

HFOs have zero ozone depletion potential HFOs have small (<10) global warming potentials HFOs will not significantly contribute to tropospheric O3

Only degradation product of concern: Trifluoroacetic acid Expected TFA concentrations in rainwater will increase in the HFO source

regions; but well below NOEC TFA accumulation (50 yr) in terminal water bodies may reach NOEC only in

extremely dry locations Large scale introduction of HFOs with large TFA yields will increase TFA in

ocean surface waters; well below NOEC

TFA levels in the environment should be monitored if HFOs are introduced on a large scale


Acknowledgements

The European model study was financially support by the European Fluorocarbon Technical Committee (EFCTC).

The Swiss Federal Office for the Environment (FOEN) supported additional high-resolution simulations and TFA measurements.

The Swiss National Science Foundation (SNF) is acknowledged for partly financing the IPAZIA computational cluster (project 206021_128754).

environmental impacts of the refrigerant r-1234yf...2013/12/04 · s. henne, et al.: environmental...

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