Estimating natural gas emissions from underground pipelines using surface concentration measurements

Younki Cho, Bridget A. Ulrich, Daniel J. Zimmerle, Kathleen M. Smits

Research output: Contribution to journalArticlepeer-review


Rapid response to underground natural gas leaks could mitigate methane emissions and reduce risks to the environment, human health and safety. Identification of large, potentially hazardous leaks could have environmental and safety benefits, including improved prioritization of response efforts and enhanced understanding of relative climate impacts of emission point sources. However, quantitative estimation of underground leakage rates remains challenging, considering the complex nature of methane transport processes. We demonstrate a novel method for estimating underground leak rates based on controlled underground natural gas release experiments at the field scale. The proposed method is based on incorporation of easily measurable field parameters into a dimensionless concentration number, ε, which considers soil and fluid characteristics. A series of field experiments was conducted to evaluate the relationship between the underground leakage rate and surface methane concentration data over varying soil and pipeline conditions. Peak surface methane concentrations increased with leakage rate, while surface concentrations consistently decreased exponentially with distance from the source. Deviations between the estimated and actual leakage rates ranged from 9% to 33%. A numerical modeling study was carried out by the TOUGH3 simulator to further evaluate how leak rate and subsurface methane transport processes affect the resulting methane surface profile. These findings show that the proposed leak rate estimation method may be useful for prioritizing leak repair, and warrant broader field-scale method validation studies. A method was developed to estimate fugitive emission rates from underground natural gas pipeline leaks. The method could be applied across a range of soil and surface covering conditions.

Original languageEnglish (US)
Article number115514
JournalEnvironmental Pollution
StatePublished - Dec 2020
Externally publishedYes

Bibliographical note

Funding Information:
This material is based upon work supported by the Department of Energy (DOE) Advanced Research Projects Agency-Energy (ARPA-E) Methane Observation Networks with Innovative Technology to Obtain Reductions (MONITOR) program under Grant No. DE-FOA-0001546 , the US Department of Transportation (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) under Grant No. 693JK31810013 and the National Science Foundation Project Award Number 1447533. Any opinion, findings, and conclusions or recommendations expressed herein are those of the authors and do not necessarily reflect the views of those providing technical input or financial support. The trade names mentioned herein are merely for identification purposes and do not constitute endorsement by any entity involved in this study.


  • Distribution pipeline
  • Fugitive emission
  • Greenhouse gas
  • Methane
  • Pipeline safety
  • Underground natural gas leakage

PubMed: MeSH publication types

  • Journal Article

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