the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 02 Sep 2025
Controlled release testing of commercially available methane emission measurement technologies at the TADI facility
Abstract. This study presents the first public, academic, blinded controlled release evaluation of methane detection and quantification technologies in Europe. Conducted at the TotalEnergies Anomalies Detection Initiatives (TADI) site in France, the campaign tested eight commercial systems – including satellite, drone, and continuous monitoring platforms – under controlled single-blind conditions. Participants submitted methane emission rate estimates without prior knowledge of true release values. Performance was assessed through detection limit curves, parity plots, and statistical metrics including slope and R². False positive detection rates ranged from 0 to 11 %. Quantification slopes ranged from 0.09 to 1.13, with a trend toward underestimation, and R2 values ranged from 0.08 to 0.97. Wind conditions – particularly low speeds and high variability – were a key factor affecting quantification accuracy, emphasizing the need for high-quality wind data integration. This study underscores the importance of rigorous, standardized testing to benchmark technology performance and inform regulatory efforts. Results highlight platform-specific strengths and challenges, providing actionable insights for participants, policymakers, and regulators. These findings support the development of robust, validated methane measurement tools critical to achieving effective emissions monitoring and reduction strategies under evolving regulatory frameworks, such as those in the European Union.
Competing interests: CJ and VB contributed to the development of the AUSEA sensor technology. There are no other conflicts of interest.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.-
Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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Supplement
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(2906 KB) - Metadata XML
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Supplement
(14763 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-3793', Andrew Feitz, 03 Oct 2025
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AC1: 'Reply on RC1 and RC2', Audrey McManemin, 19 Dec 2025
We thank the reviewers for their thoughtful and constructive review of our manuscript. We appreciate their recognition of the experimental design, thoughtful discussion, and the importance of our findings regarding the current state of methane quantification technologies. In the attached document we address each specific comment, and have accepted all of the suggestions.
We believe these revisions will strengthen the manuscript and improve its clarity. We look forward to submitting the revised version.
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AC1: 'Reply on RC1 and RC2', Audrey McManemin, 19 Dec 2025
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RC2: 'Comment on egusphere-2025-3793', Anonymous Referee #2, 27 Nov 2025
General comments
Firstly, I would like to apologize for only finding the time to write this comment now. I hope it hasn't caused any unnecessary inconvenience or problems.
The publication “Controlled release testing of commercially available methane emission measurement technologies at the TADI facility” by McManemin et al. addresses the important aspect of evaluating methane detection and quantification technologies in Europe. For this reason, controlled release experiments were conducted at the TADI facility in France in 2024. This publication compares and evaluates the results of eight commercially available technologies. Participants had to submit their estimates without knowing the true emissions. They also had to use their own device to collect the wind data that was essential for making the estimates. Subsequently, true emissions and wind data at the source were released. A key finding was that the prevailing and measured winds were a critical parameter for estimating the emission rate. The findings reinforce the statement that wind speed and direction are just as important as concentration measurements. The manuscript is well within the scope of AMT, and I recommend publication following the implementation of the minor modifications suggested in the comments below.
Specific comments
P5, L95: It might be worthwhile listing the academic teams and their technologies as well, to get a better overview – potentially in the supplement.
Fig. 2: What does the dark blue bar represent in the diagrams? Why is there a split at 50 kg/h? Although, as the other reviewer mentioned, this figure is not easy to grasp at first, it nicely shows the different types of detection (TP, FP, FN) in terms of release rates.
P12, L247: Please define CoV.
P13, L251: What do the authors mean by 'aggregate'? Are they referring to binned winds?
P16, L340f: I could not find any analysis of observations among the eight commercial systems that classify as 'aircraft' or 'vehicle' in this work. Please remove them from the list throughout the text.
P17, L370f: I do not understand why “the study design focused on mobile ground-based solution” although the analyzed technologies were either airborne (or even space-born) or continuous monitoring, at least, in this work. Did the academic teams (not evaluated here) primarily deployed mobile ground-based solutions?
Technical corrections
P5, L94: I could not find SI Section 1.2.2 in the Supplement.
h vs. hr: Please use common units for hour.
Table 4: Shift text below Table to caption or use footnotes.
Citation: https://doi.org/10.5194/egusphere-2025-3793-RC2 -
AC1: 'Reply on RC1 and RC2', Audrey McManemin, 19 Dec 2025
We thank the reviewers for their thoughtful and constructive review of our manuscript. We appreciate their recognition of the experimental design, thoughtful discussion, and the importance of our findings regarding the current state of methane quantification technologies. In the attached document we address each specific comment, and have accepted all of the suggestions.
We believe these revisions will strengthen the manuscript and improve its clarity. We look forward to submitting the revised version.
-
AC1: 'Reply on RC1 and RC2', Audrey McManemin, 19 Dec 2025
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-3793', Andrew Feitz, 03 Oct 2025
The manuscript describes the results of a large blind controlled methane release experiment. It presents the results of eight commercial quantification techniques that were assessed over an intensive 4 week release campaign, where emission rates were varied over several orders of magnitude in 45 min blocks (including zero release periods). The experiment is well described with considerable additional technical details provided in the supplementary information. The discussion and conclusions are thoughtfully considered and well presented.
The study found good methane detection amongst the various techniques but poor quantification across all techniques employed, with a surprising high number of false positives in some cases. Even with a wide 50-150% confidence internal around the true release value, most techniques achieved this less than 40% of the time. The generally poor quantification performance is concerning but consistent with similar release studies. As noted by the authors, the experimental design exacerbated the poor performance by forcing participants to report quantification results under non-optimal wind and other environmental conditions. Nevertheless, the study highlights the need to develop better methodologies for quantification, particularly for measuring and describing wind speed and variability. Short release periods disadvantage fixed sensors as the wind direction and speed may not be optimal for measurements, highlighting the advantage of mobile and scanning systems. The study provides further evidence of the mismatch between the aspirations of regulators to accurately quantify methane emissions and what is possible using current technologies and quantification methodologies.
Specific comments
Ln 11, Remove all reference to academic in this paper. The study tested commercial techniques and the quantification codes are not provided in the manuscript or supplementary information. I understand the results from academic teams will be presented in an accompanying paper. I’m not sure “public” adds much – it what way?
Ln 12, This not the first blind methane detection and quantification study in Europe. Please refer to Liu et al (2024) AMT 17, 1633–1649, 2024.
Ln 27, …have contributed
Ln 28, …pre-industrial time, and given …
Ln 34, U.S. Inflation Reduction Act – I’m not sure this is a relevant example anymore given recent developments.
Ln 63, remove academic.
Ln 140, Table 2 can be moved to the supplementary information. Not contributing much for the reader here.
Ln 158, Table 3 delete columns 2-5 and replace with a single column with the number of estimate submissions. Data is repeated in a different form in columns 6-9.
Ln 180, This figure and its caption are confusing – please remove. Table 3 is a more useful summary of false positives etc.
Ln 219-223 and Table 4. It would be interesting to include a column that shows the “Participant estimates within +/- 10% of the true value” and provide a short discussion. This is the kind of number that regulators have in mind and it would be good to show just how problematic this is. If not 10%, check relevant policy documents to see what recent expectations are.
Ln 340, remove “first public, academic”
Supplementary Information.
P35, “Names of individual personnel not required”.
P36-43, Remove references.
Citation: https://doi.org/10.5194/egusphere-2025-3793-RC1 -
AC1: 'Reply on RC1 and RC2', Audrey McManemin, 19 Dec 2025
We thank the reviewers for their thoughtful and constructive review of our manuscript. We appreciate their recognition of the experimental design, thoughtful discussion, and the importance of our findings regarding the current state of methane quantification technologies. In the attached document we address each specific comment, and have accepted all of the suggestions.
We believe these revisions will strengthen the manuscript and improve its clarity. We look forward to submitting the revised version.
-
AC1: 'Reply on RC1 and RC2', Audrey McManemin, 19 Dec 2025
-
RC2: 'Comment on egusphere-2025-3793', Anonymous Referee #2, 27 Nov 2025
General comments
Firstly, I would like to apologize for only finding the time to write this comment now. I hope it hasn't caused any unnecessary inconvenience or problems.
The publication “Controlled release testing of commercially available methane emission measurement technologies at the TADI facility” by McManemin et al. addresses the important aspect of evaluating methane detection and quantification technologies in Europe. For this reason, controlled release experiments were conducted at the TADI facility in France in 2024. This publication compares and evaluates the results of eight commercially available technologies. Participants had to submit their estimates without knowing the true emissions. They also had to use their own device to collect the wind data that was essential for making the estimates. Subsequently, true emissions and wind data at the source were released. A key finding was that the prevailing and measured winds were a critical parameter for estimating the emission rate. The findings reinforce the statement that wind speed and direction are just as important as concentration measurements. The manuscript is well within the scope of AMT, and I recommend publication following the implementation of the minor modifications suggested in the comments below.
Specific comments
P5, L95: It might be worthwhile listing the academic teams and their technologies as well, to get a better overview – potentially in the supplement.
Fig. 2: What does the dark blue bar represent in the diagrams? Why is there a split at 50 kg/h? Although, as the other reviewer mentioned, this figure is not easy to grasp at first, it nicely shows the different types of detection (TP, FP, FN) in terms of release rates.
P12, L247: Please define CoV.
P13, L251: What do the authors mean by 'aggregate'? Are they referring to binned winds?
P16, L340f: I could not find any analysis of observations among the eight commercial systems that classify as 'aircraft' or 'vehicle' in this work. Please remove them from the list throughout the text.
P17, L370f: I do not understand why “the study design focused on mobile ground-based solution” although the analyzed technologies were either airborne (or even space-born) or continuous monitoring, at least, in this work. Did the academic teams (not evaluated here) primarily deployed mobile ground-based solutions?
Technical corrections
P5, L94: I could not find SI Section 1.2.2 in the Supplement.
h vs. hr: Please use common units for hour.
Table 4: Shift text below Table to caption or use footnotes.
Citation: https://doi.org/10.5194/egusphere-2025-3793-RC2 -
AC1: 'Reply on RC1 and RC2', Audrey McManemin, 19 Dec 2025
We thank the reviewers for their thoughtful and constructive review of our manuscript. We appreciate their recognition of the experimental design, thoughtful discussion, and the importance of our findings regarding the current state of methane quantification technologies. In the attached document we address each specific comment, and have accepted all of the suggestions.
We believe these revisions will strengthen the manuscript and improve its clarity. We look forward to submitting the revised version.
-
AC1: 'Reply on RC1 and RC2', Audrey McManemin, 19 Dec 2025
Peer review completion
Journal article(s) based on this preprint
Data sets
Controlled release testing of methane emission measurement technologies at the TADI facility in summer 2024 Audrey McManemin et al. https://github.com/amcmanemin2/TADI_controlled_release_2024
Model code and software
Controlled release testing of methane emission measurement technologies at the TADI facility in summer 2024 Audrey McManemin et al. https://github.com/amcmanemin2/TADI_controlled_release_2024
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Catherine Juéry
Vincent Blandin
James L. France
Philippine Burdeau
Adam R. Brandt
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(2906 KB) - Metadata XML
-
Supplement
(14763 KB) - BibTeX
- EndNote
- Final revised paper
The manuscript describes the results of a large blind controlled methane release experiment. It presents the results of eight commercial quantification techniques that were assessed over an intensive 4 week release campaign, where emission rates were varied over several orders of magnitude in 45 min blocks (including zero release periods). The experiment is well described with considerable additional technical details provided in the supplementary information. The discussion and conclusions are thoughtfully considered and well presented.
The study found good methane detection amongst the various techniques but poor quantification across all techniques employed, with a surprising high number of false positives in some cases. Even with a wide 50-150% confidence internal around the true release value, most techniques achieved this less than 40% of the time. The generally poor quantification performance is concerning but consistent with similar release studies. As noted by the authors, the experimental design exacerbated the poor performance by forcing participants to report quantification results under non-optimal wind and other environmental conditions. Nevertheless, the study highlights the need to develop better methodologies for quantification, particularly for measuring and describing wind speed and variability. Short release periods disadvantage fixed sensors as the wind direction and speed may not be optimal for measurements, highlighting the advantage of mobile and scanning systems. The study provides further evidence of the mismatch between the aspirations of regulators to accurately quantify methane emissions and what is possible using current technologies and quantification methodologies.
Specific comments
Ln 11, Remove all reference to academic in this paper. The study tested commercial techniques and the quantification codes are not provided in the manuscript or supplementary information. I understand the results from academic teams will be presented in an accompanying paper. I’m not sure “public” adds much – it what way?
Ln 12, This not the first blind methane detection and quantification study in Europe. Please refer to Liu et al (2024) AMT 17, 1633–1649, 2024.
Ln 27, …have contributed
Ln 28, …pre-industrial time, and given …
Ln 34, U.S. Inflation Reduction Act – I’m not sure this is a relevant example anymore given recent developments.
Ln 63, remove academic.
Ln 140, Table 2 can be moved to the supplementary information. Not contributing much for the reader here.
Ln 158, Table 3 delete columns 2-5 and replace with a single column with the number of estimate submissions. Data is repeated in a different form in columns 6-9.
Ln 180, This figure and its caption are confusing – please remove. Table 3 is a more useful summary of false positives etc.
Ln 219-223 and Table 4. It would be interesting to include a column that shows the “Participant estimates within +/- 10% of the true value” and provide a short discussion. This is the kind of number that regulators have in mind and it would be good to show just how problematic this is. If not 10%, check relevant policy documents to see what recent expectations are.
Ln 340, remove “first public, academic”
Supplementary Information.
P35, “Names of individual personnel not required”.
P36-43, Remove references.