We estimate methane emissions from U.S. local distribution natural gas (NG) pipes using data collected from an advanced mobile leak detection (AMLD) platform. We estimate that there are 630,000 leaks in U.S. distribution mains, resulting in methane emissions of 0.69 Tg/year (95% cr int: 0.25, 1.23). Total emissions are calculated as the product of activity factors and emissions factors. Our analysis leveraged data on >4000 leak indications found using AMLD, combined with utility pipeline GIS information, to allow us to estimate activity factors. We derive emissions factors from AMLD emission rate estimates and correct these emissions factors based on data from in-field studies assessing AMLD emissions estimates. Finally, we quantify uncertainty in both emissions factors and activity factors and propagate the uncertainty to our total emissions estimate. In modeling leak frequency, we find a clear interaction between pipeline material and age with the leakiness of all material types increasing with age. Our national methane emissions estimate is approximately 5× greater (95% cr int: 1.7×, 8.7×) than the U.S. Environmental Protection Agency’s current greenhouse gas inventory estimate for pipeline mains in local distribution systems due to both a larger estimated number of leaks and better characterization of the upper tail of the skewed distribution of emission rates.

中文翻译：

---

全国估计天然气本地分配系统中管道主管泄漏的甲烷。

我们使用从高级移动泄漏检测（AMLD）平台收集的数据来估算美国本地分配天然气（NG）管道的甲烷排放量。我们估计美国配电干线有63万次泄漏，导致甲烷排放量为0.69 Tg /年（95％cr int：0.25、1.23）。总排放量是活动因子和排放因子的乘积。我们的分析利用了使用AMLD找到的> 4000个泄漏指示的数据，并结合了公用事业管道GIS信息，使我们能够估算活动因素。我们从AMLD排放率估算得出排放因子，并根据评估AMLD排放估算的现场研究数据对这些排放因子进行校正。最后，我们量化排放因子和活动因子中的不确定性，并将不确定性传播到我们的总排放量估算中。在对泄漏频率进行建模时，我们发现管道材料和使用年限之间存在明显的相互作用，所有材料类型的泄漏率都随着使用年限的增加而增加。我们的国家甲烷排放量估算值大约比美国环境保护署当前对本地配电系统中管道主管的温室气体清单估算值高5倍（95％cr int：1.7倍，8.7倍），这是因为泄漏量和更好地表征排放率的偏斜分布。