Temporal Variability Largely Explains Top-Down/Bottom-Up Difference in Methane Emission Estimates from a Natural Gas Production Region

Garvin Heath, Timothy Vaughn, Clay Bell, Cody Pickering, Stefan Schwietzke, Gabrielle Petron, Daniel Zimmerle, Russell Schnell, Dag Nummedal

Research output: Contribution to journalArticlepeer-review

90 Scopus Citations

Abstract

This study spatially and temporally aligns top-down and bottom-up methane emission estimates for a natural gas production basin, using multiscale emission measurements and detailed activity data reporting. We show that episodic venting from manual liquid unloadings, which occur at a small fraction of natural gas well pads, drives a factor-of-two temporal variation in the basin-scale emission rate of a US dry shale gas play. The midafternoon peak emission rate aligns with the sampling time of all regional aircraft emission studies, which target well-mixed boundary layer conditions present in the afternoon. A mechanistic understanding of emission estimates derived from various methods is critical for unbiased emission verification and effective greenhouse gas emission mitigation. Our results demonstrate that direct comparison of emission estimates from methods covering widely different timescales can be misleading.

Original languageAmerican English
Pages (from-to)11712-11717
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number46
DOIs
StatePublished - 13 Nov 2018

Bibliographical note

Publisher Copyright:
© 2018 National Academy of Sciences. All rights reserved.

NREL Publication Number

  • NREL/JA-6A20-70770

Keywords

  • Bottom-up
  • Methane emissions
  • Natural gas
  • Spatiotemporal inventory model
  • Top-down

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