Methane emissions at pressure-regulating stations in China: A comparative analysis of various quantitative methods

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Energy Systems Engineering

Background:

• Metering and regulating (M&R) stations are critical infrastructure in natural gas distribution systems.
• Methane (CH4) emissions from these stations contribute to climate change and necessitate effective mitigation strategies.
• China is actively working to improve the monitoring and inventory of emissions from its distribution systems.

Purpose of the Study:

• To assess methane emissions from M&R stations in North and Central China.
• To compare the effectiveness of different methane emission estimation methods.
• To identify primary sources of methane leakage at these facilities.

Main Methods:

• Methane emission detection and analysis at 11 M&R stations.
• Estimation of methane emissions using the dynamic flux chamber method, inverse Gaussian plume modeling (OTM33A), and stochastic Lagrangian (LS) inverse modeling.
• Calculation of emission factors and cumulative fluxes for identified sources.

Main Results:

• Flanges, instrumentation/meters, and connectors were identified as primary methane emission sources.
• The dynamic flux chamber method yielded emission factors of 0.0034, 0.0022, and 7.1e-04 kg/h for flanges, instrumentation/meters, and connectors, respectively.
• The stochastic Lagrangian (LS) method demonstrated higher reliability for estimating methane fluxes in M&R stations with limited measurement distances and continuous emissions.

Conclusions:

• The stochastic Lagrangian (LS) method is recommended for accurate methane flux analysis at M&R stations.
• Implementing fixed monitoring at M&R stations is crucial for building emission inventories and ensuring operational safety.
• The overall emission factor for the studied pressure-regulating stations was estimated at 0.013 kg/h.