Industrial Search for Greenhouse Gas Replacements Zhuangjie Li Department of Chemistry and Biochemistry California State University Fullerton Fullerton, CA 92834

Outline Introduction Global Warming Potentials (GWPs) GHG alternatives search strategy Potential GHG replacement compounds Conclusion

Global warming (GW) - threats to our welfare - draughts and floods, decrease food production - draughts and floods, decrease food production - Sea level rise, high tides, hurricanes, beach erosion - Sea level rise, high tides, hurricanes, beach erosion Anthropogenic GW contributor – Greenhouse gases (GHG) - CO 2 – from fossil fuel usage - non-CO 2 trace gases – industrial and consumer usage Industrial – Solvents, cleaning, etching agents etc. Consumer – Refrigerators, air conditioners, spray products etc. Ex. CFCl 3, CF 2 Cl 2, SF 6, C 2 F 6, NF 3 etc.

To mitigate Global warming - Reduce CO 2 loading in the atmosphere - improve fuel efficiency; develop wind, solar, renewable energy etc. For non-CO 2 GHG – Develop new chemicals that are environmentally benign (Solvents, cleaning agents, foam blowing materials, refrigerants, etc.) Question: How do we know how much a newly developed chemical would contribute to GW?

Global Warming Potentials (GWPs) – A tool to quantitatively measure the contribution of a compound to global warming. Sources: Brakkee et al. Int J LCA (2008)

Sources: NIST

Summary of Atmospheric Lifetime and GWPs for HCFCs for 20, 100, and 500 Year Time Horizons _______________________________________________________________________________________ Global Warming Potentials GasAtmospheric_________ years___________ Lifetime, years ________________________________________________________________________________________ CFC ,900 8,500 4,200 HCFC ,662 1, HCFC HCFC , HCFC-141b 9.1 1, H CFC- 142b 18 4,396 2, HCFC-225 ca HCFC-225cb 6.31, ______________________________________________________________________________________ Sources: WMO and IPCC reports ( )

Summary of Atmospheric Lifetime and GWPs for HFCs for 20, 100, and 500 Year Time Horizons _______________________________________________________________________________________ Global Warming Potentials GasAtmospheric _________ years___________ Lifetime, years ________________________________________________________________________________________ HFC , HFC ,738 3,800 1,083 HFC ,288 1, HFC- 134a 14 4,845 1, HFC , HFC- 143a 47 5,695 5,400 1,537 HFC-152a HFC HFC- 227ea ,395 3,800 1,172 HFC-236fa 2226,125 9,400 5,930 HFC-245fa 7.673, HFC-365mfc 10.72, ______________________________________________________________________________________ Sources: WMO and IPCC reports ( )

Summary of Atmospheric Lifetime and GWPs for HFEs for 20, 100, and 500 Year Time Horizons _______________________________________________________________________________________ Global Warming Potentials GasAtmospheric _________ years___________ Lifetime, years ________________________________________________________________________________________ HFE HFE ,000 1, HFE-245fa 0.401, HFE-245fb HFE ,400 4,300 1,300 HFE ,100 14,400 9,400 HFE HFE HFE-236fa HFE-236fb HFE HFE-245fc HFE HFE HFE __________________________________________________________________________________ Sources: WMO and IPCC reports ( ); Li et al. JGR 2000, 2001

Additional requirements for a GHG replacement compound: -Proper physical properties -non-flammable -low toxicity -low cost All these requirements make the search for desirable GHG replacements challenging

Conclusions Key factors in searching GHG replacement: short atmospheric lifetime Three groups of compounds are current focus: HCFCs, HFCs, and HFEs. HCFCs, HFCs, and HFEs. Search for GHG replacements is on the way Challenge: Meeting all requirements: physical properties, safe to use, low cost, and benign to the environments.

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