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.