California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States.
Environ Sci Technol. 2014 Jan 21;48(2):1084-93. doi: 10.1021/es403447v. Epub 2014 Jan 6.
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.
为了给温室气体减排政策提供信息，加利福尼亚空气资源委员会（CARB）对高全球升温潜能值（GWP）氟化气体的年度排放量进行了核算，这些气体是全球温室气体（GHG）排放量增长最快的部分。采用清单法对选定的氯氟碳化合物（CFC-12）、含氢氯氟碳化合物（HCFC-22）和氢氟碳化合物（HFC-134a）的 2008 年基准年氟气体排放量估算值与采用环境测量法进行的排放量估算值进行了比较。结果发现存在显著差异，清单法导致对旧型制冷设备和旧型车辆中 CFC-12 的排放量的系统低估了 42%，对作为逐步淘汰的 CFC 替代品的 HFC-134a 的排放量则系统高估了 114%。所有氟气体排放量的初步清单法估算假设，设备一旦达到其平均使用寿命，就不再投入使用。使用改进的设备寿命末期模型、库存和特定于加利福尼亚的泄漏率对排放量进行重新估算，使得氟气体排放量估算值与环境测量值更为接近。基于清单的估算值与基于环境的测量值之间的差异从 CFC-12 的-42%减少到-6%，从 HFC-134a 的+114%减少到+9%。
