Comparing Top-down and Bottom-up Methane Emission Estimates in a Natural Gas Production Region
Abstract
Methane is the primary component of natural gas and a potent greenhouse gas. Past efforts to quantify methane emissions from natural gas infrastructure have not agreed. Typically, estimates derived from top-down measurements have exceeded those of inventories and other bottom-up, aggregate estimates. Here we demonstrate agreement of basin-scale estimates derived from top-down aircraft mass balance flights, and a novel, spatiotemporally resolved, bottom-up Monte Carlo model. Estimates agreed on two consecutive days during flight windows at regional and sub-regional scales and produced similar longitudinal emission rate profiles. Detailed, spatiotemporally-resolved activity data and emission factors derived largely from contemporaneous measurements improved bottom-up estimates, while refinements to the aircraft mass balance method and prevailing meteorological conditions improved top-down estimates. Agreement of estimates during flight windows, but not at other times, highlights the influence of temporal variation on bottom-up estimates and provides confidence in both methods. Temporal variation was a key factor in top-down/bottom-up agreement in the Fayetteville Shale, and should be considered when comparing emission estimates in other basins where operation-driven temporal variability may exist.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A33K3332V
- Keywords:
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- 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0478 Pollution: urban;
- regional and global;
- BIOGEOSCIENCES