1 / 81

Climate Change – Green House Gasses and Atmospheric Chemistry

Climate Change – Green House Gasses and Atmospheric Chemistry. Ole John Nielsen Department of Chemistry, University of Copenhagen ojn@kiku.dk and www.cogci.dk. Peking University 2009. Ole John Nielsen. 1954 Born 1973 Began at UoC (chemistry and physics)

zinnia
Télécharger la présentation

Climate Change – Green House Gasses and Atmospheric Chemistry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Climate Change – Green House Gasses and Atmospheric Chemistry Ole John Nielsen Department of Chemistry, University of Copenhagen ojn@kiku.dk and www.cogci.dk Peking University 2009

  2. Ole John Nielsen 1954 Born 1973 Began at UoC (chemistry and physics) 1974 Important Atmospheric Year 1978 M.Sc. and on to do a PhD at Risø Nat. Lab. 1978-95 Risø National Laboratory 1995-96 Ford Research Center Aachen, Germany 1996-99 Risø National Laboratory 1999-? Professor at UoC 2007 Nobel Peace Prize together with Al Gore and 2500 scientists IPCC – Intergovernmental Panel of Climate Change Gas phase kinetics and reaction mechanisms - relevant to the atmosphere

  3. Outline • Climate Change is a broad issue – where are we? • How do we do our experiments? • Results • Conclusions • Questions

  4. The green house effect • “I do not believe in the green house effect” • Then I do not believe in gravity”

  5. How can the radiative balance be changed? Lots of Feedbacks: Melting ice - reflection Water Growing plants/the biosphere Warming oceans ……… Fast and slow feedbacks Positive (amplify) Negative (deminish) Changing incoming radiation (sun and orbit) Changing the albedo (particles, clouds, ice) Changing longwave back-radiation to space (GHG and particles)

  6. Greenhouse Gas, Aerosol & Net Climate Forcing Satellite missions will provide aerosol data +1 Watt +2 Watts Greenhouse gas forcing is accurately known (~3 W/m2), but aerosol forcing is very uncertain. Source: IPCC (2007)

  7. Temperature, CO2, CH4 and N2O back in time

  8. Update of Fig. 2A of Hansen and Sato (PNAS 101, 16109, 2004). IPCC Scenarios from Houghton et al. (2001).

  9. Mean airborne fraction, 56%, shows no evidence of increase. 44% of fossil fuel emissions ‘disappears’, despite deforestation

  10. Methane sources and sinks? Nobody knows why? There are only three ways of changing the concentration of a gas in the atmosphere!

  11. Isotope studies www.methanetomarkets.org

  12. N2O sources and sinks?

  13. Update of Fig. 2C of Hansen and Sato (PNAS 101, 16109, 2004). IPCC Scenarios from Houghton et al. (2001).

  14. Update of Fig. 1A of Hansen and Sato (PNAS 101, 16109, 2004), with one additional measured gas (CH3Br).

  15. CFCs and halons had a Unique Combination of Properties... Performance wide liquid range compatibility solvency stability Safety nonflammable low toxicity CFCs and halons are also depleting stratospheric ozone→ Montreal Protocol ... useful for many industrial applications Cleaning Drying Lubricant Deposition Refrigeration Heat Transfer Aerosol Formulations Fire Extinguishing Foam Blowing Dielectrics

  16. 1st generation alternatives • Decrease atmospheric lifetime • Decrease lifetime = insert hydrogen atoms • HCFCs (HydroChloroFluoroCarbons) • Remove the chlorine and bromine • HFCs (HydroFluoroCarbons) • HFC134a = CF3CFH2 (replacement for CF2Cl2) • GWP100(CF3CFH2) = 1/8 GWP100(CF2Cl2)

  17. The Montreal Protocol has slowed and reversed the accumulation of ozone depleting substances (ODSs) in the stratosphere. • (Effective stratospheric chlorine is the weighted sum of chlorine and bromine gases in the stratosphere.) SO WHY? UNEP/WMO Ozone Assessment, 2006

  18. We need 2nd generation alternatives with smaller GWPs 2005 emissions Change 1990-2005 FCs +19% HFCs gone up by a factor 1.5

  19. What must be done before using a new chemical in large quantities? • The complete atmospheric degradation mechanism (quantification) • Atmospheric lifetime • Degradation products

  20. How do we do it?Cl2+hν→2ClCH3ONO+hν CH3O + NO CH3O + O2 HCHO + HO2 HO2 + NO  OH + NO2O3 from an ozonizer

  21. Compound Atm. Lifetime GWP100y • CF3CH2CF3 (HFC-236fa) 240 y 9810 • CF3CH2OCF3 (HFE-236fa) 3.7 y 470 • CF3CF=CF2 18 d 6 • CF3CF=CH2 11 d 4 • 1 y 55 EU law will be: Global Warming Potential< 150How to make GWP lower? References: papers published by CCAR and Dr. Wallingtons group at Ford Motor Company

  22. Effect of Ether Oxygen on Atmospheric Lifetime Relative Reactivity of Ether with OH CH3OCH3 vs CH3CH3 ~ 9X C2H5OC2H5 vs C4H10 ~6X C3H7OC3H7 vs C6H14 ~3X

  23. Effect of Ether Oxygen on Atmospheric Lifetime Atm. GWPCompoundLifetime (yrs) (100 Yr ITH) CH3CF3 (HFC-143a) 52 4,470 alkaneCH3OCF3 (HFE-143a) 4.3 756 ether CF3CFHCF3 (HFC-227ea) 34.2 3,220CF3CFHOCF3 (HFE-227ea) 11 1,500 CF3CH2CF3 (HFC-236fa) 240 9,810CF3CH2OCF3 (HFE-236fa) 3.7 470 CF3CH2CHF2 (HFC-245fa) 7.6 1,030CF3CH2OCHF2 (HFE-245fa2) 4.9 659

  24. Atmospheric Lifetimes of Segregated HFEs • Rf -O - Rh k(OH)  (cm3molecules-1s-1) (years) • n-C4F9-O-CH3 1.20 x 10-14 4.7 • i-C4F9-O-CH3 1.54 x 10-14 3.7 • n-C4F9-O-C2H5 6.4 x 10-14 0.9 • i-C4F9-O-C2H5 7.7 x 10-14 0.7 • C4F9-O-(CH2)3-O-C4F9 1.44 x 10-13 0.4 • 5.93 x 10-14 1.0

  25. New hydrofluoroethers and fluoropropenes will cause less radiation forcing Precision Cleaning and Coating Electronics Cleaning/Defluxing Deposition Solvents Heat Transfer Fluids Refrigeration

  26. End with the bad news and the good news The Montreal Protocol have reduced net GWP-weighted emissions from ODSs in 2010 by 5-6 times the reduction target of the first commitment period (2008-2012) of the Kyoto Protocol. The Montreal Protocol will have reduced net GWP-weighted emissions from ODSs in 2010 by about 11 Gt CO2-eq yr-1. • Greenhouse gases: CO2, CH4, N2O, HFCs, PFCs, SF6 G. Velders et al., PNAS, 2007

  27. The bad news 2004-2007: 30% increase in global CO2-weighted HCFC emissions. 2007: HCFC emissions were 2.6% of fossil-fuel and cement related CO2 emissions (30 Gt/yr) Montzka et al. GRL 2008

  28. Conclusions on 2nd Generation CFC Replacements • FCs lifetimes and GWPs cover very wide range • Possible to create fluorochemicals with much lower GWPs • In many industrial applications, significant radiation forcing reductions can be obtained using lower GWP materials • The Montreal Protocol has reduced net GWP-weighted emissions from ODSs in 2010 by 5-6 times the reduction target of the first commitment period (2008-2012) of the Kyoto Protocol • The Montreal Protocol process could serve as a guide for the COP15 meeting in Copenhagen in December 2009

  29. Conclusions on Climate Change There are different reasons for doing something about it:

  30. Conclusions on Climate Change There are different reasons for doing something about it:

  31. How Can Climate be Stabilized? • Must Restore Planet’s Energy Balance • Modeled Imbalance: +0.75 ± 0.25 W/m2 • Ocean Data Suggest: +0.5 ± 0.25 W/m2 • Requirement Might be Met Via: • Reducing CO2 to ? • and • Reducing non-CO2 forcing ~ 0.25 W/m2 • Geo-Engineering? (Sulphur in the Strat ?)

  32. Thank you for your attention Special Acknowledgements: James Hansen (NASA), Timothy J. Wallington (FORD), John Owens (3M)

  33. Extra Slides

  34. Global Warming Potential (GWP) • Calculated using IPCC method • Basis of 1 kg of compound released • Calculated over a specified integration time horizon (ITH) • Result is equivalent number of kg of CO2 released

  35. 5 Black Body Radiation @ 294K 4 Attenuated Terrestrial Radiation IR Absorption of Fluorochemicals 3 Flux (Wm-2) 2 1 0 0 500 1000 1500 2000 2500 Wavenumber (cm-1) Radiative Forcing in the Atmosphere

  36. IR Absorbance of Fluorochemicals Radiative Forcing of hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) Radiative Forcing values as reported in WMO Global Ozone Research and Monitoring Report No. 44: Scientific Assessment of Ozone Depletion - 1998

  37. Lifetime and GWP of Fluoroalkanes Atm. GWP*CompoundLifetime (yrs) (100 Yr ITH) *IPCC 2007 CF4 (PFC-14) 50000 7,390CHF3 (HFC-23) 270 14,800 nonflammableCH2F2 (HFC-32) 4.9 675 flammableCH3F (HFC-41) 3.7 140 CF3CF3 (PFC-116) 10000 12,200CF3CHF2 (HFC-125) 29 3,500CF3CH2F (HFC-134a) 14 1,430CF3CH3 (HFC-143a) 52 4,470CHF2CH3 (HFC-152a) 1.4 124CH2FCH3 (HFC-161) 0.25 10 CF3CHFCF3 (HFC-227ea) 34.2 3,220CH2FCF2CHF2 (HFC-245ca) 6.6 720 CF3CH2CF2CH3 (HFC-365mfc) 8.6 794 CF3CHFCHFC2F5 (HFC-43-10mee) 15.9 1,640

  38. Effect of Ether Oxygen on Atmospheric Lifetime • Insertion of -O- affects reactivity with OH • Lifetime reduces with increasing number of H atoms • HFEs with lone C-H bond can be longer lived than analogous alkanes • HFEs with more than one H per C exhibit greater effect -CH2F, -CH2-, CH3 • F substitution on same C or  to the C-H bond can reduce effect • Some of the largest effects occur with segregation

  39. Segregated Hydrofluoroethers (HFEs) CnF2n+1-O-CmH2m+1 Rf-O-Rh

  40. Segregated Hydrofluoroethers (HFEs) Rf-O-Rh-O-Rf C4F9-O-(CH2)3-O-C4H9

  41. Atmospheric Lifetimes of Segregated HFEs • Rf -O - Rh k(OH)  (cm3molecules-1s-1) (years) • n-C3F7 - OCH3 1.18 x 10-14 4.8 • C6F13- OCH3 1.51 x 10-14 3.8 • C7F15-OC2H5 2.24 x 10-14 2.2 • Rf1-O - CH3 2.1 x 10-14 2.7 • Rf3-O - C2H5 5.9 x 10-14 1.0 • Rf4-O - CH3 1.13 x 10-14 5.0 • Rf5 -O - CH3 1.34 x 10-14 4.2

  42. Atmospheric Lifetimes of Segregated HFEs Rf groups include: linear branched cyclic primary ethers secondary ethers di-ethers All structures result in lifetimes  5 years

  43. Comparison of Global Warming Potentials PFCs All HFCs Nonflammable HFCs HFC - 23 HFC - 236ea All HFEs HFE - 125 Segregated HFEs Naturally Occurring Compounds 0 5000 10000 15000 20000 Global Warming Potential (100 yr ITH)

  44. O-C2H5 O-CH3 C3F7CFCF(CF3)2 C2F5CFCF(CF3)2 Novec 7500 Novec 7300 Novec 7800 Novec Fluids - Hydrofluoroethers C3F7-O-CH3 C4F9-O-CH3 C4F9-O-C2H5 Novec 7000 Novec 7100 Novec 7200

  45. Potential Reductions in Greenhouse Gas Emissions • Segregated HFEs typically replace high GWP compounds • For many applications substitutions are made on an equal mass basis • Reductions can range from 80% to 99% on C or CO2 basis when to replace a PFC or HFC

More Related