UAV-based measurements of methane emissions from two electrically-driven natural gas compressor stations in China.

Compressor stations are significant sources of methane (CH4) emissions in the transmission and storage operations of the natural gas system. However, these emissions in China have not been quantitatively assessed using top-down measurement approaches. The present study determined CH4 emissions from two natural gas compressor stations in China using a methodology of UAV-based measurements combined with a mass balance computation algorithm. Four controlled-release experiments were conducted to validate the methodology, yielding individual deviations ranging from -10% to +4% between the estimated and actual release rates. For the compressor stations, CH4 emissions showed substantial variabilities both across different days and within individual days. The geometric mean CH4 emission rates were 6.47 kg/h (95% CI: 5.25-7.82 kg/h) and 8.61 kg/h (95% CI: 7.52-9.86 kg/h) for the two stations, respectively. Emission rates were positively correlated with natural gas throughput and compressor rotational speed, indicating that these parameters could be effective indicators of CH4 emission levels at compressor stations. Measurements over more compressor stations will be necessary to increase the representativeness of CH4 emissions from compressor stations in China. Overall, this study offers valuable empirical data and derived emission factors for electrically-driven centrifugal compressor stations in China.