Evaluation of coal mine methane inventory methods using aircraft-based approaches in the Bowen Basin, Australia

Abstract. Australia uses a blend of IPCC Tier 2 and 3 bottom-up approaches to estimate and report fugitive coal mine methane (CH4) emissions. To date, Tier 3 reporting for underground coal mines, which predominantly relies on direct measurements of ventilated air, has not been systematically assessed against top-down atmospheric measurements. Tier 2 coal core-based emission factors and Tier 3 model guidelines for estimating surface (open-cut) mine emissions similarly lack verification. Here, an in-situ and a remote sensing aircraft-based approach were used to quantify CH4 emission rates from 17 coal mines in the Bowen Basin, Australia. When compared to bottom-up mean annual reported estimates, airborne estimates from underground mines showed a non-significant mean positive bias of 0.28 t h−1 (p=0.28,n=8 estimates) and good agreement (normalised root mean squared error (NRMSE) = 0.20). When aggregated, top-down measured emissions from all underground mines were within 8 % of bottom-up reported totals. In contrast, aircraft-based estimates from surface mines showed a significant mean positive bias of 3.7 t h−1 CH4 (p=0.001,n=10 estimates) and poor agreement (NRMSE = 0.86). In aggregate, top-down emissions from all surface mines were 3.6 times the bottom-up totals. Alignment between airborne top-down and measured vented underground coal mine emissions increases confidence in Australia's Tier 3 direct monitoring methods, while the difference between top-down and bottom-up surface mine emission estimates suggests core-based methods require review. Given that surface mines in the Basin alone account for ∼38 % of national production, the contribution of coal mining to Australia's CH4 emissions may exceed the reported ∼19 %.

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Publication Details

Journal
Atmospheric chemistry and physics
Published
2026-07-16
DOI
https://doi.org/10.5194/acp-26-10043-2026
Primary Topic
Atmospheric and Environmental Gas Dynamics
Type
article
Field-Weighted Citation Impact
0.00

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article

Evaluation of coal mine methane inventory methods using aircraft-based approaches in the Bowen Basin, Australia

Mei Bai, Sven Krautwurst, Jakob Borchardt, Mark F. Lunt et al.
Atmospheric chemistry and physics
Atmospheric and Environmental Gas Dynamics
article

Evaluation of coal mine methane inventory methods using aircraft-based approaches in the Bowen Basin, Australia

Mei Bai, Sven Krautwurst, Jakob Borchardt, Mark F. Lunt, Wolfgang Lieff, H. Bovensmann, Mathias Lanoisellé, James L. France, Bryce F. J. Kelly, Rebecca Fisher, Stephen J. Harris, Konstantin Gerilowski, Hartmut Boesch, Thomas Röckmann, W. Junkermann, Oke Huhs, Josua Schindewolf, Shakti Chakravarty, Andrew McGrath, R. A. Field, Carina van der Veen, John P. Burrows, Tarra Brain, Jakob Thoböll, Adrian Murphy, Zoe Salmon, Jorg Hacker, Martin Kumm
article en

Abstract

Abstract. Australia uses a blend of IPCC Tier 2 and 3 bottom-up approaches to estimate and report fugitive coal mine methane (CH4) emissions. To date, Tier 3 reporting for underground coal mines, which predominantly relies on direct measurements of ventilated air, has not been systematically assessed against top-down atmospheric measurements. Tier 2 coal core-based emission factors and Tier 3 model guidelines for estimating surface (open-cut) mine emissions similarly lack verification. Here, an in-situ and a remote sensing aircraft-based approach were used to quantify CH4 emission rates from 17 coal mines in the Bowen Basin, Australia. When compared to bottom-up mean annual reported estimates, airborne estimates from underground mines showed a non-significant mean positive bias of 0.28 t h−1 (p=0.28,n=8 estimates) and good agreement (normalised root mean squared error (NRMSE) = 0.20). When aggregated, top-down measured emissions from all underground mines were within 8 % of bottom-up reported totals. In contrast, aircraft-based estimates from surface mines showed a significant mean positive bias of 3.7 t h−1 CH4 (p=0.001,n=10 estimates) and poor agreement (NRMSE = 0.86). In aggregate, top-down emissions from all surface mines were 3.6 times the bottom-up totals. Alignment between airborne top-down and measured vented underground coal mine emissions increases confidence in Australia's Tier 3 direct monitoring methods, while the difference between top-down and bottom-up surface mine emission estimates suggests core-based methods require review. Given that surface mines in the Basin alone account for ∼38 % of national production, the contribution of coal mining to Australia's CH4 emissions may exceed the reported ∼19 %.

Atmospheric chemistry and physicsVol. 26(13)
Jade University of Applied Sciences (DE), Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (DE), Environmental Defense Fund (US), The University of Melbourne (AU), Flinders University (AU), University of Applied Sciences Utrecht (NL), University of Bremen (DE), Royal Holloway University of London (GB), Utrecht University (NL), UNSW Sydney (AU), International Office for Water (FR), Airborne International (Netherlands) (NL), Environmental Earth Sciences (AU), Garmisch-Partenkirchen Medical Center (DE)
European Space Agency, Deutsche Forschungsgemeinschaft, Bundesministerium für Bildung und Forschung
Openalex Percentile: Top 10%
Atmospheric and Environmental Gas Dynamics
DOIOpen Access PDFOpenAlex
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