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Open Access Publications from the University of California

High-global warming potential F-gas emissions in California: comparison of ambient-based versus inventory-based emission estimates, and implications of refined estimates.

  • Author(s): Gallagher, Glenn
  • Zhan, Tao
  • Hsu, Ying-Kuang
  • Gupta, Pamela
  • Pederson, James
  • Croes, Bart
  • Blake, Donald R
  • Barletta, Barbara
  • Meinardi, Simone
  • Ashford, Paul
  • Vetter, Arnie
  • Saba, Sabine
  • Slim, Rayan
  • Palandre, Lionel
  • Clodic, Denis
  • Mathis, Pamela
  • Wagner, Mark
  • Forgie, Julia
  • Dwyer, Harry
  • Wolf, Katy
  • et al.

Published Web Location Commons 'BY' version 4.0 license

To provide information for greenhouse gas reduction policies, the California Air Resources Board (CARB) inventories annual emissions of high-global-warming potential (GWP) fluorinated gases, the fastest growing sector of greenhouse gas (GHG) emissions globally. Baseline 2008 F-gas emissions estimates for selected chlorofluorocarbons (CFC-12), hydrochlorofluorocarbons (HCFC-22), and hydrofluorocarbons (HFC-134a) made with an inventory-based methodology were compared to emissions estimates made by ambient-based measurements. Significant discrepancies were found, with the inventory-based emissions methodology resulting in a systematic 42% under-estimation of CFC-12 emissions from older refrigeration equipment and older vehicles, and a systematic 114% overestimation of emissions for HFC-134a, a refrigerant substitute for phased-out CFCs. Initial, inventory-based estimates for all F-gas emissions had assumed that equipment is no longer in service once it reaches its average lifetime of use. Revised emission estimates using improved models for equipment age at end-of-life, inventories, and leak rates specific to California resulted in F-gas emissions estimates in closer agreement to ambient-based measurements. The discrepancies between inventory-based estimates and ambient-based measurements were reduced from -42% to -6% for CFC-12, and from +114% to +9% for HFC-134a.

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