Methane emissions decline from reduced oil, natural gas, and refinery production during COVID-19

In the summer of 2020, the AVIRIS-NG airborne imaging spectrometer surveyed California’s Southern San Joaquin Valley and the South Bay (Los Angeles County) to identify anthropogenic methane (CH4) point source plumes, estimate emission rates, and attribute sources to both facilities and emission sectors. These flights were designed to revisit regions previously surveyed by the 2016-2017 California Methane Survey and to assess the socioeconomic responses of COVID-19 on emissions across multiple sectors. For regions flown by both the California Methane Survey and the California COVID campaigns, total CH4 point source emissions from the energy and oil & natural gas sectors were 34.8% lower during the summer 2020 flights, however, emission trends varied across sector. For the energy sector, there was a 28.2% decrease driven by reductions in refinery emissions consistent with a drop in production, which was offset in part with increases from powerplants. For the oil & natural gas sector, CH4 emissions declined 34.2% and significant variability was observed at the oilfield scale. Emissions declined for all but the Buena Vista and Cymric fields with an observed positive relationship between production and emissions. In addition to characterizing the short-term impact of COVID-19 on CH4 emissions, this study demonstrates the broader potential of remote sensing with sufficient sensitivity, spatial resolution, and spatio-temporal completeness to quantify changes in CH4 emissions at the scale of key sectors and facilities.

2020年夏季，航空可见光/红外成像光谱仪（AVIRIS-NG）对加利福尼亚州圣华金河谷南部以及南湾（洛杉矶县）开展航空成像光谱测绘，以识别人为甲烷（CH₄）点源羽流、估算排放速率，并将排放源归因为各类设施与排放门类。本次飞行旨在回访2016-2017年加利福尼亚甲烷普查（California Methane Survey）曾测绘过的区域，并评估新冠疫情（COVID-19）对多门类排放产生的社会经济影响。对于同时被加利福尼亚甲烷普查与本次加利福尼亚新冠疫情航测项目覆盖的区域，2020年夏季航测期间，能源以及石油与天然气（oil & natural gas）行业的甲烷点源总排放量较此前降低了34.8%，但各门类排放的变化趋势存在差异。能源行业排放量下降28.2%，这一降幅由炼油厂排放减少驱动，与产量下滑相契合，但发电厂排放的增加部分抵消了这一降幅。石油与天然气行业的甲烷排放量下降34.2%，且在油田尺度上观测到显著的排放差异。除布埃纳维斯塔（Buena Vista）与锡姆里克（Cymric）油田外，其余油田的排放量均有所下降，且观测到产量与排放量之间存在正相关关系。本研究除刻画新冠疫情对甲烷排放的短期影响外，还证实了具备足够灵敏度、空间分辨率与时空完备性的遥感技术，在关键门类与设施尺度上量化甲烷排放变化的更广泛应用潜力。