This session aims at advancing our understanding of the hydrogen budget and the implications of increased hydrogen use. Topics of interest include:
- Quantifying hydrogen emissions from direct sources, including leakages, venting, and incomplete combustion, as well as oxidation by volatile organic compounds.
- Investigating the removal of hydrogen by soil bacteria and by reaction with OH in the atmosphere.
- Assessing the indirect climate effects of hydrogen emissions on methane, ozone, and stratospheric water vapor.
- Utilizing observations and modeling to refine estimates of hydrogen sources and sinks across various spatial and temporal scales.
- Exploring scenarios of future hydrogen economies, including their potential to reduce fossil fuel emissions and the associated environmental and climatic co-benefits.
We welcome studies that employ experimental, observational, and theoretical approaches to hydrogen biogeochemistry and atmospheric processes, contributing to a more comprehensive understanding of H₂ in the context of the global energy transition.
Orals: Fri, 8 May, 08:30–10:10 | Room M1
Uptake of hydrogen from the atmosphere by microbial activity in soils is the main global H2 sink mechanism. The processes and environmental drivers which modulate the H2 soil sink are highly uncertain, but research has demonstrated that moisture, soil porosity and temperature affect the magnitude of H2 uptake by soil microbes. Peatlands are carbon-rich, dynamic environments with a fluctuating water table and temporal seasonal variation. These environments harbour a relatively large capacity for microbial activity but also contain a variety of mixed environments and microtopography (hummocks and hollows). There are no dedicated studies reported in literature exploring H2 flux dynamics in peatlands to date.
To investigate the drivers of H2 flux in peatland environments, in-situ field measurements of H2 flux have been carried out using the flux chamber method at two Scottish peatlands. Auchencorth Moss (AC) and Whim Bog (WH) are located within the Pentland region south of Edinburgh. AC was previously drained, with peat depth at the study site between 0.5 - 1 m, whereas WH has been left in its natural state with peat depth ranging between 3 - 6 m. At each site, chambers were placed to capture variation in H2 flux due to microtopography. Water table depth and temperature measurements were taken at each chamber at each measurement occasion. Initial results show that mean H2 flux in autumn and winter were -21.5 nmol m-2 s-1 at AC and -18.5 nmol m-2 s-1 at WB.
As well as in-situ field studies, lab-based incubations using soil samples from AC and WH have been conducted to investigate H2 flux under controlled moisture conditions to identify optimum conditions for uptake. Analysis is being carried out using DNA sequencing to identify the microbial species responsible for H2 consumption in samples. Molecular sequencing will also explore the abundance of the gene which activates the expression of the hydrogenase enzyme under varying moisture levels to infer the favourable environmental conditions for H2 uptake on a microbial scale. We hope to report preliminary results at EGU. The main aim of this work is to assess the strength H2 soil sink in high carbon landscapes such as peatlands and explore the key environmental and microbial drivers that constrain H2 uptake.
How to cite: Devlin, R., Drewer, J., Cowan, N., Dumbrell, A., and Stevenson, D.: Investigating environmental and microbial drivers of hydrogen uptake in UK peatlands, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11201, https://doi.org/10.5194/egusphere-egu26-11201, 2026.
We present results from the EU HYDRA Project (Hydrogen Economy Benefits and Risks: Tools Development and Policies Implementation to Mitigate Possible Climate Impacts), focusing on the soil sink of hydrogen, and its associated historical and future variations. We calculate the dry deposition velocity of hydrogen to soil with and without consideration of soil carbon content and simulate atmospheric hydrogen concentrations in 2010 using the FRSGC/UCI global chemical transport model (CTM). Surface concentrations and their seasonal variation compare better with observations when soil carbon content is accounted for. The contribution of each soil parameter to the overall uncertainty in hydrogen dry deposition was quantified using Gaussian process (GP) emulation and Sobol sensitivity analysis. We find that soil moisture is the key factor influencing soil uptake, and we identify regions with differing responses to soil moisture using the Expectation-Maximization (EM) method. We then explore the influence of dry deposition on the interannual variation in surface hydrogen concentration from 2010 to 2022 using the CTM and find that the interannual variation is driven principally by variations in dry deposition, especially in years with a large soil moisture anomaly relative to the decadal mean. The impact of climate change on future hydrogen dry deposition was then estimated using soil information output from 11 CMIP6 models, and we find a change in soil uptake between 2015 and 2100 of -1.5% to +7.8% following the SSP1-2.6 and +4.6% to +22.2% following the SSP5-8.5 pathway.
How to cite: Wang, Y. and Wild, O.: Uncertainty analysis and future changes in the soil uptake of hydrogen, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7858, https://doi.org/10.5194/egusphere-egu26-7858, 2026.
To mitigate climate change, alternative energy carriers are required to replace fossil fuels. Hydrogen is widely regarded as a promising candidate, and the hydrogen economy is currently expanding. However, hydrogen is an indirect greenhouse gas, with estimates of its 100-year global warming potential reaching up to 12.8. A robust assessment of its climate impact therefore requires a detailed understanding of atmospheric hydrogen sources and sinks. Despite this need, observational studies of atmospheric hydrogen remain relatively limited and most are over short measurement periods. Long-term measurements are essential for identifying trends and characterizing decadal variability. Therefore, this study presents an analysis of ten years (2006–2017) of tropospheric hydrogen measurements conducted at a suburban site in Gif-sur-Yvette, France. The in-situ observations show an average baseline hydrogen concentration of (518 ± 18) ppb, characterized by a seasonal cycle, with maxima between April and June and minima between September and November. Both the baseline levels and the seasonal pattern remain stable over the full decade of measurements. The most uncertain component of the atmospheric hydrogen budget is uptake by soils. Using the radon tracer method applied to nighttime data, soil hydrogen uptake was quantified consistently over the ten-year period. An average deposition velocity of (2.8 ± 0.5) · 10−2 cm s−1 was obtained, with stronger uptake during the summer. Despite some interannual variability, no significant long-term trend in soil uptake is observed, providing rare observational evidence for the decadal stability of this major hydrogen sink. Diurnal cycles of hydrogen and carbon monoxide exhibit distinct morning peaks associated with traffic emissions. These were used to derive the H2/CO ratio, a key parameter for estimating hydrogen emissions from traffic based on carbon monoxide inventories. An average ratio of 0.56 ± 0.05 was determined, which likewise shows no systematic trend over the decade. Overall, this study provides decade-long observations of hydrogen, demonstrating the long-term stability of baseline concentrations, soil uptake and traffic-related emission ratios.
How to cite: Schell, D., Yver-Kwok, C., Schmidt, M., and Paris, J.-D.: Decade-long Observations of Hydrogen Soil Uptake and Traffic Emissions in a Suburban Environment (Gif-sur-Yvette, France), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11613, https://doi.org/10.5194/egusphere-egu26-11613, 2026.
The transition to a hydrogen economy is considered to represent an important contribution to climate change mitigation, yet models of the climate impact of a future hydrogen economy rely on appropriate hydrogen emissions scenarios. Reliable empirical data on hydrogen emissions is therefore critical for refining climate models. The HEQ (Hydrogen Emissions Quantification) project, a collaboration between Equinor and adMS, previously reported its first site-level emissions quantification from a grey hydrogen production facility using a novel analytical framework based on mass spectrometry and tracer-ratio methods. This initial study highlighted the need for airborne data acquisition capabilities and enhanced understanding of flaring and venting systems.
In 2025, the HEQ project carried out a comprehensive data collection campaign at an Equinor-operated refinery, representing the world’s first online airborne effort to quantify hydrogen emissions from an industrial facility. This groundbreaking effort employed a multi-faceted approach combining helicopter-based, drone-assisted, and land-based techniques. The campaign had three primary objectives: validating and qualifying airborne measurement methods for hydrogen, quantifying fugitive emissions from reformers and hydrogen-rich circuits and directly measuring the combustion efficiency of the flaring system.
This presentation will share valuable insights and results from the campaign, highlighting the effectiveness of diverse data acquisition methods and their implications for emissions measurements and monitoring in real-world industrial environments. By improving our understanding of hydrogen emissions, we aim to provide the empirical data necessary to support future regulatory requirements and enhance climate models for a sustainable hydrogen economy.
How to cite: Roudot, M., Krohl, V., Piel, F., Wisthaler, A., Mikoviny, T., Borisov Karabelyov, A., van Heuven, S. M. A. C., Scheeren, H. A., and Westra, I. M.: Developing and Validating Airborne Methods for Industrial Hydrogen Emissions Quantification, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6750, https://doi.org/10.5194/egusphere-egu26-6750, 2026.
The atmospheric composition plays a crucial role in the climate through radiative forcing and chemical processes. Although hydrogen (H2) is not a greenhouse gas itself, it indirectly influences the climate by affecting methane (CH4) lifetime and atmospheric chemistry. To date, H2 emissions have not been studied extensively, limiting our ability to detect trends in a changing economy. Recently, efforts have been made towards developing the first European anthropogenic hydrogen budget by combining bottom-up estimates with spatially resolved activity data. Focusing on the correlation between H2 and carbon monoxide (CO), e.g., fingerprinting, helps further identify H2 emissions from combustion sources. Even though this technique works well for combustion sources, it does not allow for the inference of fluxes from non-combustion sources.
In this study, we aim to extend the fingerprinting method by examining the correlation between CH4 and H2 emissions from dairy farms, following previous studies that showed that H2 and CH4 emissions from dairy cows are dynamically linked. To this end, flask samples were collected at different locations on a dairy farm to determine the correlation between the two trace gases for sub-farm-scale sources. Additionally, this study quantified full-farm H2 and CH4 emissions by using the active AirCore technique on a UAV platform. The CH4-H2 correlations observed at point sources within the farm and those within the full-farm emission plume are found to be consistent with each other. Upscaling based on the well-constrained Dutch national inventory of dairy farming CH4 emissions, we present an initial estimate of national total H2 emissions from dairy farming.
How to cite: van Ettinger, N., van Heuven, S., Westra, I., Scheeren, B., and Chen, H.: Assessing the co-emission of methane and hydrogen from dairy farms in the Netherlands, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13790, https://doi.org/10.5194/egusphere-egu26-13790, 2026.
Renewably produced hydrogen will contribute to climate change mitigation for hard to abate emission generating sectors, if leakage rates are minimised. Despite this benefit, leakage of hydrogen into the atmosphere is well documented to cause indirect climate effects such as depletion of hydroxyl radical and changes in different greenhouse gases, such as increases in methane lifetime, tropospheric ozone and stratospheric water vapor. Therefore accurate earth system modeling of hydrogen budget changes, especially in the upper troposphere and lower stratosphere (UTLS), is an important tool to quantify climate change impacts, induced by changes due to different hydrogen budgets. It has been shown, that Lagrangian transport improves the simulation of water vapour in the UTLS, by reducing climate model moist biases by a factor between 2 and 3 in the lowermost stratosphere (Charlesworth et. al., 2023).
Following this approach, we investigate the atmospheric distribution of hydrogen using a similar model setup, which faciliates an improved estimation of the hydrogen-induced water vapor climate effect. We show simulations of two model versions, the Eulerian EMAC model and the Lagrangian coupled model EMAC-CLaMS. Emissions of hydrogen and methane as well as the soil sink are prescribed from previous work by Surawski et al. (2025) The model has a resolution corresponding to a horizontal grid of 1.87° * 1.87° (≈ 180-190 km) up to a model top height of 80 km. Another major model improvement is the change from a default to an improved radiation scheme. To ensure that the new Lagrangian transport scheme only affects the stratosphere, the entire troposphere in the Lagrangian EMAC-CLaMS simulation is set to the EMAC simulation data.
For model evaluation and comparison between the Eulerian and Lagrangian frameworks, the simulation results are compared with NOAA ground-based hydrogen measurements as well as balloon-borne stratospheric measurements by the University of Frankfurt cryosampler BONBON between 1998 and 2005.
How to cite: Reisch, R., Grooß, J.-U., Kerkweg, A., Steil, B., Surawski, N., Engel, A., and Ploeger, F.: Improved simulation of atmospheric hydrogen using Eulerian and Lagrangian models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12059, https://doi.org/10.5194/egusphere-egu26-12059, 2026.
Hydrogen (H2) is expected to be a crucial substitute for fossil fuels in the ongoing energy transition. However, atmospheric H2 is recognized as an indirect greenhouse gas, as it can contribute to global warming through its coupling to the atmospheric oxidative capacity, including interactions with methane, ozone and stratospheric water vapour. Yet, large uncertainties still remain in the atmospheric H2 budget.
Within the framework of the HYway Horizon Europe project, we quantify and diagnose key chemical drivers of uncertainty in simulated H2 by focusing on two components: chemical production linked to formaldehyde (HCHO) and chemical destruction controlled by the hydroxyl radical (OH). HCHO photolysis is a major source of atmospheric H2, accounting for more than half of the global total. We firstly assess the HCHO chemical production, loss, and global burden across multiple HYway models. The global HCHO burden range from 0.69 to 1.03Tg, indicating a wide inter-model difference of 50%. Therefore, we evaluate the simulated HCHO by ground- and satellite-based observations. The contribution of biogenic hydrocarbons emissions to the HCHO budget is discussed. Oxidation by OH is the second-largest sink of atmospheric H2 after soil uptake. However, the modeled OH is typically overestimated by global chemical models. Here, we examine uncertainty in H2 chemical loss by characterizing the range of OH simulated across HYway models, and by comparing simulated OH with observation-constraint OH fields. Finally, we present a free-running H2 simulation (driven by emissions rather than prescribed surface H2 concentrations) and show that the resulting H2 fields are consistent with observations. Overall, this work provides an integrated evaluation of the chemical controls on H2 in global models and a basis for improving H2 projections under future emission scenarios.
How to cite: Xu, J., Hauglustaine, D., Li, H., Skeie, R. B., Zhao, Y., Zheng, B., Peng, S., and Ciais, P.: Multi-model diagnostics and uncertainties of atmospheric H2 chemical production and loss terms within the HYway project, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20197, https://doi.org/10.5194/egusphere-egu26-20197, 2026.
As the hydrogen (H2) economy expands, there is growing interest in understanding the atmospheric lifetime of H2, which affects its impact on atmospheric chemistry and climate. While some global H2 is destroyed via reaction with the hydroxyl radical (OH), most is lost to microbial activity in soils. However, the sources and sinks of H2 are still uncertain on global and local scales. This study focuses on how monthly resolved observations of HFC-152a can help to constrain the seasonal OH cycle and the H2 budget, particularly the seasonal range and phase of H2 oxidation and soil loss. Seasonal observations of HFC-152a are used to constrain OH through a Bayesian inversion in a three-box model comprising the Northern, Tropics, and Southern regions over 2010–2022. In the North, a seasonal range of the soil sink of 18–21 ± 8 Tg year-1 is found, peaking in July–August, while the OH loss seasonal range is 8 ± 1 Tg year-1, peaking in July. The South has much less land and so displays a smaller soil sink seasonal range of 2–3 ± 2.5 Tg year-1, peaking in January–March. The OH loss in the South has a seasonal range of 7 ± 1 Tg year-1, peaking in January. The OH and soil sink loss in the Tropics is more consistent across all months, but with larger uncertainty. The results presented here will be a useful comparison for H2 cycles in fully integrated chemistry climate models.
How to cite: Chen, C., Stone, K., Solomon, S., Western, L., Krummel, P., Pétron, G., Mühle, J., and O'Doherty, S.: Constraining the atmospheric hydrogen oxidation and soil sinks using HFC-152a, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14500, https://doi.org/10.5194/egusphere-egu26-14500, 2026.
In this work, hydrogen demand, infrastructure development and emission pathways are quantified for the road transport sector at the European scale. Three scenarios are defined, a business-as-usual, a reference, and a hydrogen-favouring scenario, extending to 2070 and differentiated by assumptions on CO₂ prices, hydrogen prices and infrastructure availability. The resulting hydrogen emission inventories are intended as input to climate chemistry models in a subsequent step to assess the climate implications of road transport hydrogen emissions.
The analysis focuses on the fuel distribution and use stages, where hydrogen refuelling stations (HRS) emerge as the dominant emission source compared to vehicle-level losses (Clark et al. 2025). Emissions at HRS arise from storage venting and boil-off, tanker depressurisation during delivery, compressor leakages, hose venting and purging events, which scale non-linearly with station size and utilisation and depend strongly on station type (compressed or liquid hydrogen). This creates a trade-off between infrastructure scale, utilisation, economic performance and emissions which is an identified gap in literature.
Hydrogen demand needed to be supplied by HRSs in the scenarios is derived for passenger cars, light- and heavy-duty vehicles based on the temporal evolution of transport activity and drivetrain market shares competing with battery electric and conventional technologies. Passenger car activity is modelled using GDP and population dependent motorisation rates as Gompertz functions. Freight activity is estimated based on scenario calculations of the International Transport Forum (ITF). Total passenger and freight transport activity are modelled for reference scenario and is kept constant across the scenarios. Passenger car technology shares and stock evolution in Europe are simulated using the agent-based vehicle choice model VECTOR21 (www.vector21.de). Commercial vehicle stocks are computed using the LAREDO model, informed by expert surveys on hydrogen drivetrain penetration.
Component-level hydrogen emission rates for HRS are compiled from literature (Clark et al. (2025) and others) and distinguished between continuous and event-based releases. Due to the limited number of highly utilised operational stations, reported emission rates span wide ranges. HRSs are simulated by defining component structures, station size and utilisation frequency. To meet spatially resolved hydrogen demand, stations are located using freight and travel demand trip data and clustered to optimise utilisation and scale-dependent costs for compressed and liquid hydrogen supply. Given that liquid hydrogen supply contain high emission processes at lower utilization but are also more cost effective for larger scales, the works thus aims to presents an assessment of trade-offs between costs, utilisation and emissions for HRSs especially across the three scenarios.
Emission inventories are thus created at a 0.1° resolution with global-level analysis, as was done previously (Righi et al. 2025) by authors, and also for other species to provide a consistent input for subsequent climate impact assessments within the project CLEANLIEST.
How to cite: Dasgupta, I., Ehrenberger, S., Lischke, A., Knitschky, G., Moritz, A., and Thomsen, N.: Scenario Based Assessment of Hydrogen Emissions from Road Transport Infrastructure, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22029, https://doi.org/10.5194/egusphere-egu26-22029, 2026.
Global energy systems are undergoing significant structural changes in response to the overarching aim of mitigating and adopting to the geophysical impacts of climate change. One of the key strategies for enabling this structural change is the incremental transition away from fossil fuels and gradual uptake of renewable and low carbon energy sources. While remarkable progress has been achieved in electricity decarbonisation - which contributed around 35% global GHG emissions in 2025, a significant part of the energy system pie is still exploring suitable solutions especially for “hard-to-abate" sectors—such as steel manufacturing, chemical production, and long-haul shipping—where direct electrification is technically or economically challenging. With increased decarbonisation of electricity sectors using variable renewable generation technologies like solar and wind, there is also a growing need to balance and store the wasted energy from intraday supply and demand mismatch. Additionally, increasing severity of climate change impacts globally is accelerating these structural changes where some nation states have also attempted to raise the climate change mitigation ambition by suggesting complete phaseout of fossil fuels at UNFCCC’s COP28 and COP30. Consequently, there is renewed interest in global hydrogen economy and its direct benefits in circumventing majority of the issues highlighted above.
Pursuant to this, under the Horizon Europe’s HyWay project, researchers are generating future scenarios for hydrogen economy and analysing the warming impacts of subsequent fugitive hydrogen emissions. In this research, hydrogen economy scenarios are being generating using MESSAGEix-GLOBIOM-GAINS modelling framework of IIASA. The modelling framework generates bottom-up energy system futures for 12 Global regions, while also capturing intra-regional and inter-regional energy commodity trade. The framework generates a least cost solution under various technology transition and climate mitigation constraints using linear programming-based optimisation. Using this framework, we generate a set of scenarios using national implemented policies, nationally determined goals, regional net zero targets, hydrogen generation infrastructure and trade policy data, and different global temperature targets for various Shared Socioeconomic Pathway narratives. In addition, some specialised scenarios also looked at more wide-spread use of hydrogen in the energy system vs. more confined use in industrial clusters. These broad policy and techno-climatic levers along with discussions with key industry stakeholders enabled us to analyse in detail a) the future hydrogen generation configuration at various time steps, b) displacement of fossil-fuels from global energy systems, and 3) sectoral utilisation of hydrogen especially in the industrial sector. Across the scenario solution space, we observe that from a current production volume of 100Mt H2 at a global level mainly for industrial use, hydrogen economy can surpass 400Mt H2 production by 2050 and upwards of 1000 Mt H2 by 2100. This would require significant investment in hydrogen economy infrastructure and possibly underwriting and repurposing of fossil fuel-based energy generation units. We also observe that from current domination of “grey hydrogen”, the energy system will transition completely to “green hydrogen” generation by 2050, with “blue hydrogen” acting as a transition enabler. The results also provide significant insights into regional and global dynamics of hydrogen economy including its climate impacts.
How to cite: Joshi, S., Cassamassima, L., Fakhreddine, J., Fricko, O., and Krey, V.: Hydrogen economy and its critical role in future low carbon energy systems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20265, https://doi.org/10.5194/egusphere-egu26-20265, 2026.
Accurate emission measurements are critical for assessing the climate impacts of gases released by human activities. While robust and widely applied methods exist for quantifying carbon dioxide and methane emissions, comparable approaches for atmospheric hydrogen remain less mature. Recent advances in analytical instrumentation, however, are beginning to close this gap. Advanced Monitoring Solutions (adMS) has developed a fast-response (1 Hz) mass spectrometer (H₂MS) capable of measuring atmospheric hydrogen with sub-ppb precision. These direct, rapid, and precise measurements enable established emission quantification techniques to be extended to hydrogen [1].
In 2025, as part of the Hydrogen Emissions Quantification (HEQ) project – a collaboration between adMS and Equinor – we applied and evaluated multiple approaches to quantify hydrogen emissions at an operational industrial site. In this study, we present two emission quantification methods based on airborne online mass spectrometry.
First, the H₂MS analyzer was deployed aboard a helicopter to perform 1 Hz measurements of atmospheric hydrogen. Helium was released at a known rate at the site and used as a tracer, enabling application of the tracer ratio method. To support this approach, a second mass spectrometer (HeMS) was developed to provide highly precise, online measurements of atmospheric helium. These observations represent the first demonstration of real-time airborne monitoring of both hydrogen and helium and show that fast, direct hydrogen measurements can be integrated into established emission quantification frameworks. While the tracer ratio method is demonstrated here, the rapid response of the H₂MS analyzer also enables the application of other emission quantification approaches previously used for methane, including airborne mass balance and inverse modeling techniques.
In addition, we investigated an alternative measurement strategy using a drone-lifted 200 m sampling line to quantify hydrogen emissions from a 100 m-high flare. This approach highlights the potential of unmanned aerial systems to access complex emission geometries that are difficult to sample using conventional ground-based techniques.
[1] Roudot, Malgven and Piel, Felix and Sobolev, Nikita and Mikoviny, Tomas and Wisthaler, Armin and Krohl, Victoria, A New Analytical Framework for Industrial Hydrogen Emissions Quantification: Validation and First Results (September 29, 2025). Available at SSRN: https://ssrn.com/abstract=6041754 or http://dx.doi.org/10.2139/ssrn.6041754
How to cite: Wisthaler, A., Piel, F., Mikoviny, T., Borisov Karabelyov, A., Roudot, M., and Krohl, V.: Advancing Atmospheric Hydrogen Emission Quantification Through Airborne Online Mass Spectrometry, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5067, https://doi.org/10.5194/egusphere-egu26-5067, 2026.
Performance of the adMS hydrogen mass spectrometer (H2MS) for continuous on-line detection of low-level atmospheric hydrogen
Hubertus A. Scheeren1, Iris M. Westra1, Steven M.A.C. van Heuven1, Bert A.M. Kers1, Felix Piel2, Armin Wisthaler2, Harro A.J. Meijer1
1University of Groningen, Department of Science and Engineering, Centre for Isotope research, The Netherlands
2Advanced Monitoring Solutions AS, Oslo, Norway
Abstract. Only recently, new techniques to detect low-level hydrogen emissions along the value chain have become available (1,2,3). We tested the performance of the novel hydrogen mass spectrometer (H2MS) from Advanced Monitoring Solutions (adMS), Norway, against our high-precision Agilent gas-chromatrography system equipped with a Pulsed Discharge Helium Ionization Detector (PDHID) (1) for measuring ambient hydrogen. The H2MS analyzer utilizes electron ionization and magnetic sector separation (following the same fundamental principles as conventional leak-detection mass spectrometers) to isolate and detect H2⁺ ions ((m/z 2) (2). It features a dedicated, patent-pending inlet system that allows for the stable and precise detection of background levels of atmospheric H2 (~530 ppb). We present results from both laboratory and field performance tests of the H2MS system as compared to our GC-PDHID system. As such, we evaluate its measurement performance when using our UAV-borne ‘active AirCore’ samplers for hydrogen emission quantification studies (1,4,6). Furthermore we evaluate the results of a continous monitoring intercomparison experiment against our GC-PDHID system at our field station Lutjewad (4) measuring ambient air from a 60 m high mast. Our results demonstrate that the H2MS is a valuable addition to our low-level hydrogen detection and emission quantification methodologies so far (1,6) with sufficient precision and resolution compared to our GC-systems but unparralled advantages when working under field conditions.
1) I.M. Westra, H.A. Scheeren, F.T. Stroo, S.M.A.C. van Heuven, B.A.M. Kers, W. Peters, H.A.J. Meijer, First detection of industrial hydrogen emissions using high precision mobile measurements in ambient air, Sci. Rep. 14 (2024) 24147, https://doi.org/10.1038/s41598-024-76373-2.
2) Malgven Roudot, Felix Piel, Nikita Sobolev, Thomas Mikoviny, Armin Wisthaler, Victoria Krohl, A New Analytical Framework for Industrial Hydrogen Emissions Quantification: Validation and First Results (September 29, 2025). Available at SSRN: http://dx.doi.org/10.2139/ssrn.6041754.
3) A. Momeni, J.D. Albertson, S. Herndon, C. Daube, D. Nelson, J.R. Roscioli et al. Quantification of Hydrogen Emission Rates Using Downwind Plume Characterization Techniques. Environ. Sci. Technol., 2025, 59, 6016-6024. DOI:10.1021/acs.est.4c13616.
4) T. Andersen, B. Scheeren, W. Peters, and H. Chen: A UAV-based active AirCore system for measurements of greenhouse gases, Atmos. Meas. Tech., 11, 2683–2699, https://doi.org/10.5194/amt-11-2683-2018, 2018.
5) Lutjewad (ICOS class 2) monitoring station: https://meta.icos-cp.eu/resources/stations/AS_LUT.
6) Iris M. Westra, Hubertus A. Scheeren, Mareen J. Penninga, Steven M.A.C. van Heuven, Harro A.J. Meijer, Controlled-release experiment to optimize emission quantification of H2 point source, under review at ES&T-Air, 2026.
How to cite: Scheeren, H. A., Westra, I. M., van Heuven, S. M. A. C., Kers, B. A. M., Piel, F., Wisthaler, A., and Meijer, H. A. J.: Performance of the adMS hydrogen mass spectrometer (H2MS) for continuous on-line detection of low-level atmospheric hydrogen , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7586, https://doi.org/10.5194/egusphere-egu26-7586, 2026.
Molecular hydrogen (H₂) plays an important role in atmospheric chemistry and is considered an indirect greenhouse gas through its influence on methane's lifetime and tropospheric ozone formation. With the anticipated expansion of a hydrogen-based economy, establishing background concentrations and identifying present-day emission sources are essential for detecting and attributing future changes. In this study, we present a one-year record of continuous atmospheric H₂ measurements conducted at the ICOS atmospheric station Lutjewad, located in the north of the Netherlands. Atmospheric H₂ mole fractions were measured using a gas chromatograph with a pulsed discharge helium ionization detector (GC-PDHID) sampling dried ambient air from a 60 m tall tower, alongside measurements of CH₄, CO₂, N2O, and CO used for source fingerprinting of the observed H₂ enhancements. Field campaigns at regional source locations were conducted to investigate the potential emission sources, including traffic emissions (tunnel measurements), methanogenic sources (landfills), and cattle farms. Furthermore, we investigated the potential of the Radon Tracer Method (RTM) to infer regional hydrogen emissions. We observe that continental air masses lead to pronounced atmospheric H₂ enhancements (up to 700 ppb), whereas northerly (marine) winds consistently represent clean background conditions (490–540 ppb), comparable to the observations at the European continental background station Mace Head on the east coast of Ireland. We present results of our on-going Jena sausage flask intercomparison programme which includes hydrogen measurements (once every 4 months), allowing for an independent quality control of the accuracy of our hydrogen measurements in the atmospheric range of 410 – 630 ppb H2.
Overall, this work establishes a pre–hydrogen economy baseline for atmospheric H₂ in northwestern Europe. Our continuous observations proof to be fundamental for a better understanding of H₂ sources within the footprint of our station and a starting point for monitoring emission changes associated with the emerging hydrogen economy.
How to cite: Westra, I. M., Scheeren, H. A., and Meijer, H. A. J.: First year of atmospheric hydrogen measurements and source fingerprinting at the ICOS Lutjewad Station, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9040, https://doi.org/10.5194/egusphere-egu26-9040, 2026.
The hydrogen value chain, including the production, distribution, storage and end use of H2, is growing around the world. Although hydrogen is viewed as a sustainable energy carrier, it has an indirect radiative effect. H2 is a leak prone gas, and emissions from leaks/purging/venting across the H2 value chain could lead to increased H2 mole fraction in the atmosphere. Through the reaction of H2 with OH, this would increase mole fractions of CH4, tropospheric ozone and stratospheric water vapour, all of which result in warming. Hence, the GWP20 and GWP100 of H2 are estimated to be around 37 and 12, respectively.
Therefore, measurements of emissions of H2 from existing and new hydrogen infrastructure are needed. However, low levels of H2 are difficult to measure and suitable measurement technologies are becoming available only recently. One such technology is the Aerodyne Research TILDAS H2 monitor. This monitor has a high precision (down to 5 parts per billion which is 100 times below ambient), has fast time resolution (5 seconds), and can perform continuous 1 Hz air measurements. The instrument has been found to successfully observe a wide range of mole fraction enhancements of H2 on a mobile platform, and these plumes can be converted to emission rates with dispersion models and/or release of tracers at controlled rate. Emission rates from new and existing infrastructure such as refuelling and refilling stations, pipelines, electrolysers and buses will be presented here.
How to cite: Woolley Maisch, C., Velzeboer, I., van den Bulk, P., van Mansom, H., Hensen, A., and Röckmann, T.: Quantifying H2 emissions of new and existing infrastructure, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9384, https://doi.org/10.5194/egusphere-egu26-9384, 2026.
Hydrogen (H₂) is widely regarded as a promising energy carrier for the energy transition, as it can be produced from renewable energy with low direct greenhouse gas (GHG) emissions and offers strong potential to decarbonize sectors that are difficult to electrify. Consequently, H₂ production is expected to increase in the coming decades. However, H₂ burden in the atmosphere indirectly contributes to climate change by extending the atmospheric lifetime of methane and leading to the formation of stratospheric water vapor and tropospheric ozone. The 100-year global warming potential of H₂ is estimated at 11.6±2.8. As the smallest naturally occurring molecule, H₂ is highly prone to leakage, and intentional releases may occur for operational or safety reasons. Despite this, anthropogenic H2 emissions from non-combustion sources are poorly known, limited by the lack of availability of precise measurement solutions.
This study reports on a controlled release experiment to assess the performance and limitations of H₂ component-level quantification methods. Seven different methods are compared: a bagging method (leak enclosure with a controlled carrier gas flow), two high-flow sampling (HFS) methods (concentration measurement in high-flow rate suction of the leaking gas), and four acoustic imaging methods (converting sound levels in a microphone array into volumetric flow). The controlled H₂ releases are performed on a test bench at the Enagas Metrology & Innovation Center in Zaragoza, Spain. 15 blind controlled releases up to 313 g·h⁻¹ are generated on typical H₂ industry components, including a flange, a valve, and open-ended lines. Leak-rate restrictions are imposed on the instruments for safety reasons. The maximum measurable leak rate is 216 g·h⁻¹ for bagging, 35 g·h⁻¹ for HFS while acoustic cameras have no limitations.
Early results of the intercomparison suggest that the most accurate methods are one HFS method and bagging, with mean relative errors of 13 and 25%, respectively. The second HFS method exhibits a higher mean relative error of 38%. In contrast, the acoustic camera methods show higher errors of 63%, 98%, 443%, and 1240%.
In conclusion, bagging, although time-consuming, provides reliable measurements across a wide range of leak rates. HFS delivers fast measurements with high accuracy for moderate leak rates but may be limited at very high rates. Acoustic cameras allow rapid detection without upper leak-rate restrictions. However, their quantification accuracy varies widely among methods making some more suitable for leak detection than precise measurement.
How to cite: Louvet, J., Paris, J.-D., Yver-Kwok, C., and Bescos Roy, V.: Comparative Evaluation of Hydrogen Emission Quantification Methods at the Component Level Using Controlled Releases, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11675, https://doi.org/10.5194/egusphere-egu26-11675, 2026.
The soil sink of atmospheric hydrogen is the biggest uncertainty related to the climatic impacts of H2 emissions and the projection of hydrogen-based energy scenarios. In this context, a crucial role is played by H2-oxidising bacteria spread basically in every soil and accounting for about 80% of the atmospheric hydrogen removal. Many studies on soils and bacterial activity have been performed and multiple factors, both biotic and abiotic, have been found to influence the hydrogen uptake. Above all, soil moisture and, in particular, its temporal fluctuations have been shown to be the dominant control, conditioning both bacterial activity and hydrogen diffusion in the soil.
In the present work, we extend the dimension of these previous models, taking into account the horizontal spatial diffusion of both soil moisture and hydrogen. This addition opens the way to investigate the key effects of soil spatial heterogeneities and the related occurrence of spatial patterns in soil hydrogen uptake dynamics. Early results show a clear dependence of the H2 atmospheric flux on the presence of the horizontal diffusion terms, with a different behaviour according to the hydroclimatic conditions chosen. Furthermore, spatio-temporal averages computed neglecting the complete coupled dynamics of soil moisture and hydrogen are found to lead to significant errors due to the non-linearities encoded in the model. This latter result is enhanced in climates with poor rainfall events (semi-arid ecosystems), while it is quite negligible in wet cases, where the non-linearities are smoothed down.
The findings of this study improve the understandings of soil hydrogen dynamics and underscore possible biases associated with coarse-resolution global modelling.
How to cite: Nesta, G., Ridolfi, L., and Bertagni, M.: Role of soil heterogeneity and hydrological variability in atmospheric hydrogen uptake, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11773, https://doi.org/10.5194/egusphere-egu26-11773, 2026.
Atmospheric hydrogen is an important atmospheric constituent, affecting the oxidative capacity of the atmosphere and indirectly causing a climate warming effect through its chemical interactions. To quantify these effects, and that of future hydrogen emissions from anthropogenic activity, requires understanding hydrogen’s atmospheric budget. We aim to constrain this budget using spatial and temporal patterns of hydrogen, its sources, and sinks, derived from observations and a multi-model comparison.
As part of the Climate Impacts of a HYdrogen economy: the pathWAY to knowledge (HYway) project, emissions-driven simulations of present-day hydrogen have been conducted in several climate and chemistry transport models. Variation in the meridional, vertical and seasonal patterns of hydrogen concentration across these models arise due to differences in the corresponding patterns of each budget term. By comparing the hydrogen concentration patterns in observational data to that of the models and their budget terms, we attempt to constrain the magnitude of each budget term. These constraints are determined from basic statistical analysis and simple box modelling approaches.
We thus present an analysis of the spatial and temporal patterns of atmospheric hydrogen and its sources and sinks, derived from observational and model data, and estimation of the magnitude of budget terms.
How to cite: Coleman, M. and Collins, W.: Constraining the atmospheric hydrogen budget through spatiotemporal patterns in models and observations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12029, https://doi.org/10.5194/egusphere-egu26-12029, 2026.
Volatile organic compounds (VOCs) play a key role in atmospheric chemistry, influencing the cycling of peroxy and hydroxyl radicals, the formation of tropospheric ozone, hydrogen, secondary organic aerosols, and the lifetime of methane and other greenhouse gases. The largest source of atmospheric hydrogen is the photochemical destruction of formaldehyde (HCHO), which is primarily produced through the oxidation of other VOCs.
The Volatile Organic Compound Model Intercomparison Project (VOCMIP) aims to identify model consistencies and discrepancies, improve the representation of chemical mechanisms, and advance our understanding of VOC-related processes in the atmosphere. Here, we present initial VOCMIP results, focusing on differences in budget terms for emissions, chemical production and loss, dry and wet deposition, and lifetimes. Particular attention is given to formaldehyde and the key precursor compounds contributing to its formation.
How to cite: Myhre, G. and the VOCMIP team: Initial results from VOCMIP, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16570, https://doi.org/10.5194/egusphere-egu26-16570, 2026.
Green ammonia (NH3) is produced based on green hydrogen (H2) and has recently gained wide interest due to its potential to decarbonize ammonia production, and as a carbon-free solution for energy storage and transportation. However, the production and use of ammonia come with other climate and environmental challenges due to its alteration of the Earth’s nitrogen cycle. Before introducing new ammonia technologies on a large scale, it is important to thoroughly understand current atmospheric impacts of anthropogenic reactive nitrogen (Nr), mainly the impacts of ammonia, nitrogen oxides (NOX) and nitrous oxide (N2O) emissions. The present work addresses pre-industrial (1850) to present-day (2019) climate effects of Nr, and has been published in Hodnebrog et al. (2025, Nature, https://doi.org/10.1038/s41586-025-09337-9).
We use five independent latest-generation atmospheric chemistry models (OsloCTM3, CESM2, GISS ModelE, GFDL-AM4.1 and LMDZ-INCA), and find that the change over the industrial era of nitrate and sulfate aerosol abundances owing to Nr emissions varies greatly across the models. Consequently, the direct aerosol radiative forcing (RF) differs widely by model, even in sign. The positive ozone and negative methane RF due to Nr emissions also vary widely between models. While all five models show a net negative RF (i.e., cooling) due to historical anthropogenic Nr emissions, the net climate effect is the sum of several terms that vary in sign and are associated with substantial uncertainties. Future research is clearly needed, both to better define and narrow the uncertainties on the climate effects given here and to quantify climate effects for processes for which estimates do not yet exist (for example, aerosol-cloud interactions due to Nr emissions).
How to cite: Hodnebrog, Ø., Jouan, C., Hauglustaine, D. A., Paulot, F., Bauer, S. E., Beaudor, M., Prather, M. J., Sandstad, M., Skeie, R. B., and Myhre, G.: Uncertain climate effects of anthropogenic reactive nitrogen, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17744, https://doi.org/10.5194/egusphere-egu26-17744, 2026.
Hydrogen (H2) is expected to play an important role in the transition to low-carbon energy systems. Tropospheric H2 is either emitted directly or produced in situ in the atmosphere through chemical reactions, while the two sinks are soil uptake and reaction with the hydroxyl radical (OH). Large uncertainties persist in the global H2 budget, particularly due to limited direct observations of atmospheric H2 production, soil uptake, and the global OH abundance.
In this study, we investigate the global H2 budget using a suite of three-dimensional atmospheric chemistry models to evaluate the key species involved in atmospheric hydrogen production (such as formaldehyde) and loss through OH-related chemistry (such as nitrogen dioxide and carbon monoxide). We then use a box model incorporating isotopic compositions with sources and sink estimates to test different plausible H2 budget scenarios. Combining model evaluations and box model constraints, we suggest atmospheric H2 production of 37-60 Tg yr-1, and atmospheric losses of 15-30 Tg yr-1. Finally, we evaluate the uncertainty in these estimates using the box model framework.
How to cite: Krishnan, S.: Multi-model and box modeling evaluation of the tropospheric hydrogen budget, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17789, https://doi.org/10.5194/egusphere-egu26-17789, 2026.
How to cite: Martin, A., Klingmüller, K., Steil, B., Gromov, S., Lee, Y.-R., Chang, D. Y., Surawski, N., Lelieveld, J., Jeong, S., and Pozzer, A.: Interactive Simulation of Methane and Hydrogen Soil Deposition Using the Newly Implemented BIODEP Submodel of the ECHAM5/MESSy Atmospheric Chemistry Model (EMAC) v2.55, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18139, https://doi.org/10.5194/egusphere-egu26-18139, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 5
EGU26-11855 | ECS | Posters virtual | VPS3
Global Implications of a Low Soil Moisture Threshold for Microbial Hydrogen UptakeTue, 05 May, 14:45–14:48 (CEST) vPoster spot 5
The impact of increasing anthropogenic hydrogen (H2) emissions on Earth’s radiative balance depends on the soil microbial H2 sink—the largest and most uncertain term in the global H2 budget. Soil moisture is a primary but poorly quantified control regulating the soil sink. Here, we assess the sensitivity of microbial H2 oxidation to soil moisture in laboratory experiments with temperate and arid soils spanning distinct textures. H2 oxidizer activity is observed down to –70 to –100 MPa water potentials across soils, which are among the driest conditions reported for microbial activity and are much drier than assumed in global simulations of H2. Using genome-resolved meta-omics, we link H2 oxidation dynamics in temperate soils to specific desiccation-adapted microbial taxa that contribute differentially to H2 uptake along the moisture gradient. Through global simulations, we show that our observationally constrained drier moisture threshold increases the contribution of arid and semi-arid regions for soil H2 uptake by 4-7 percentage points (pp), while decreasing the contribution of temperate and continental regions (−7 pp). Our results highlight the importance of H2 uptake under extreme hydrological conditions, particularly the roles of desertification, dryland expansion, and H2-oxidizer ecophysiology in modulating long-term changes in H2 uptake.
How to cite: Reji, L., Bertagni, M., Paulot, F., Qin, Q., and Zhang, X.: Global Implications of a Low Soil Moisture Threshold for Microbial Hydrogen Uptake , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11855, https://doi.org/10.5194/egusphere-egu26-11855, 2026.
