Observations of Methane Emissions from Natural Gas-Fired Power Plants
Observations of Methane Emissions from Natural Gas-Fired Power Plants
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DOI：
10.1021/acs.est.9b01875
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发表时间：
2019-08-06
影响因子：
11.4
通讯作者：
Shepson, Paul B.
中科院分区：
文献类型：
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作者：
Hajny, Kristian D.;Salmon, Olivia E.;Shepson, Paul B.
目前关于天然气（NG）对大气影响的研究工作主要集中在生产，储存/传输和加工部门，对分销和最终使用部门的关注较少。这项工作讨论了23个航班在14个天然气发电厂（NGPPs）使用飞机为基础的质量平衡技术和甲烷/二氧化碳增强比（Δ CH 4/Δ CO2）从烟囱羽流测量，以量化未燃烧的燃料。通过比较在烟囱羽流中测量的Delta CH 4/Delta CO2比与在顺风处测量的Delta CH 4/Delta CO2比，我们确定，在测量的不确定性范围内，所有观察到的CH 4排放都是基于烟囱的，即来自烟囱的未燃烧NG而不是易散源。测得的甲烷排放率（ER）范围为8（+/- 5）至135（+/- 27）kg CH 4/h（+/- 1 sigma），部分甲烷通量损失（损失率）范围为-0.039%（+/- 0.076%）至0.204%（+/- 0.054%）。我们将负值归因于发电厂环境CH 4的部分燃烧。计算的平均排放系数为5.4（+10/-5.4）克甲烷/百万英热单位，在环境保护署排放系数的不确定范围内。然而，在启动期间测量的一个设施的烟囱排放量大得多，EF为440（+660/-440）g CH 4/MMBTU，损失率为2.5%（+3.8/-2.5%）。
Current research efforts on the atmospheric impacts of natural gas (NG) have focused heavily on the production, storage/transmission, and processing sectors, with less attention paid to the distribution and end use sectors. This work discusses 23 flights at 14 natural gas-fired power plants (NGPPs) using an aircraft-based mass balance technique and methane/carbon dioxide enhancement ratios (Delta CH4/Delta CO2) measured from stack plumes to quantify the unburned fuel. By comparing the Delta CH4/Delta CO2 ratio measured in stack plumes to that measured downwind, we determined that, within uncertainty of the measurement, all observed CH4 emissions were stack-based, that is, uncombusted NG from the stack rather than fugitive sources. Measured CH4 emission rates (ER) ranged from 8 (+/- 5) to 135 (+/- 27) kg CH4/h (+/- 1 sigma), with the fractional CH4 throughput lost (loss rate) ranging from -0.039% (+/- 0.076%) to 0.204% (+/- 0.054%). We attribute negative values to partial combustion of ambient CH4 in the power plant. The average calculated emission factor (EF) of 5.4 (+10/-5.4) g CH4/million British thermal units (MMBTU) is within uncertainty of the Environmental Protection Agency (EPA) EFs. However, one facility measured during startup exhibited substantially larger stack emissions with an EF of 440 (+660/-440) g CH4/MMBTU and a loss rate of 2.5% (+3.8/-2.5%).