Natural hydrogen emanations in Namibia: Field acquisition and vegetation indexes from multispectral satellite image analysis

Moretti, Isabelle; Geymond, Ugo; Pasquet, Gabriel; Aimar, Léo; Rabaute, Alain

doi:10.1016/j.ijhydene.2022.08.135

Cited by 28 publications

(33 citation statements)

References 63 publications

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“…however, global variations in the value are smaller than the variations detected in soil affected by microseepage of H 2 in the continental domain (Prinzhofer et al, 2019;Moretti et al, , 2022. This is coherent with the differences between micro-and macro-seepages observed for the natural gas, which reflect differences in the mode of transport of hydrogen through soils and fractures (Schumacher, 1996).…”

Section: Representativeness Of the Surface Datasupporting

confidence: 70%

“…As H 2 contents have been shown to vary both within and between days in some geological settings (Prinzhofer et al, 2019;Moretti et al, , 2022, we recorded the time each measurement was obtained and will present the results versus time. Although samples were obtained from various locations along the leaking zone (Figure 3), no SE-NW trends in concentrations were noted; accordingly, we did not attempt to map H 2 concentrations spatially.…”

Section: Gas Samplingmentioning

confidence: 99%

“…"White" dihydrogen is H 2 in its natural state (Rigollet and Prinzhofer, 2022) and is generated mainly through fluid rock interactions reactions (Smith et al, 2005;Gaucher, 2020;Moretti and Webber, 2021). This natural dihydrogen has been observed in various geological contexts (Truche et al, 2020;Zgonnik, 2020), including mid-oceanic ridges (Charlou et al, 1998(Charlou et al, , 2002Kelley et al, 2001;Kelley, 2005); ophiolitic massifs such as the Sultanate of Oman, New Caledonia, or the Philippines (Neal and Stanger, 1983;Abrajano et al, 1988;Sano et al, 1993;Deville and Prinzhofer, 2016;Vacquand et al, 2018); and Archean and Proterozoic cratonic basins such as those in Namibia, Mali, Russia, Australia, and Brazil (Larin et al, 2015;Prinzhofer et al, 2018Prinzhofer et al, , 2019Boreham et al, 2021;Moretti et al, , 2022Malvoisin and Brunet, 2023). Steam at the hightemperature geothermal sites of Italy, Iceland, and Djibouti (Oskarsson, 1984;Ármannsson et al, 1989;Leila et al, 2021;Pasquet et al, 2021Pasquet et al, , 2022Combaudon et al, 2022) has also been shown to contain H 2 , possibly from multiple sources.…”

Section: Introductionmentioning

confidence: 97%

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Natural hydrogen potential and basaltic alteration in the Asal–Ghoubbet rift, Republic of Djibouti

Pasquet¹,

Idriss²,

Ronjon-Magand³

et al. 2023

BSGF - Earth Sci. Bull.

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The Asal–Ghoubbet active rift in the Republic of Djibouti is a site of interest for geothermal energy and natural hydrogen, and previous studies have indicated that dihydrogen (H2) emanates from this rift. However, the well-known serpentinization reaction does not appear to be the main mechanism generating H2 at this site. Rather, the H2 is generated as follows: (1) by alteration of basaltic lava at depth via reaction with seawater flowing from Ghoubbet Bay towards Lake Asal; (2) by simple degassing of the volcanic chamber located a few kilometers below the Fiale Caldera in the rift axis; or (3) as a result of pyritization processes via the oxidation of H2S. Analysis of microorganisms did not indicate any production or consumption of H2, CO2, or CH4; therefore, it is unlikely that microorganisms affected H2 gas contents measured at the surface. However, air contamination at fumaroles is typically considerable and may limit interpretation of such processes. Drill cuttings from the Fiale 1 (F1) and Gale le Goma 1 (Glc1) wells (located on the inner and outer rift margins, respectively) were analyzed to determine where H2 is generated. Total rock analyses indicated distinct zones at depths of 464 m and 280 m for F1 and Glc1, respectively, representing the boundary between the Asal and Stratoïd Basalts. 57Fe Mössbauer analyses show a decrease in the percentage of Fe3+ at depth, indicating that Fe2+-rich material, particularly in the Stratoïd Basalts, may be a source of H2. Based on well data from the rift center and the outer rift margin, it is evident that H2 is present at the surface in the rift axis and that this area offers good remnant potential because of the presence of Fe-rich chlorite. Conversely, few H2 emissions were measured at the surface on the outer rift margins, although well data showed some H2 (~0.25%) at depth. The presence of a cap rock in the rift axis has not yet been proven; however, the high loss on ignition and the mineralogy in well Glc1 may indicate that the rocks are sufficiently altered to offer potential as a seal. If so, the rift margins would offer greater exploration potential than the rift center.

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Section: Representativeness Of the Surface Datasupporting

confidence: 70%

Section: Gas Samplingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Natural hydrogen potential and basaltic alteration in the Asal–Ghoubbet rift, Republic of Djibouti

Pasquet¹,

Idriss²,

Ronjon-Magand³

et al. 2023

BSGF - Earth Sci. Bull.

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“…In fact, their presence in the subsurface was attested below H 2 seepages for instance in Namibia and Brazil. Additional suspected seepages have also been reported in the surroundings of BIF-hosted iron mines in Australia and South Africa (Geymond et al, 2022;Moretti et al, 2022). In addition to the spatial correlation between BIF and H 2 emissions, BIF carry key Fe-minerals that are promising for H 2 generation and need to be tested experimentally and thermodynamically.…”

Section: Banded Iron Formations and H Generationmentioning

confidence: 96%

“…In addition to Fe-silicates, Fe-carbonates potentially sourcing H 2 were also investigated to a lower extent. In fact, H 2 emissions have been detected close to gold mineralization and banded iron formations (BIF) that are partly constituted by siderite (FeCO 3 ) and ankerite [(Fe,Ca)CO 3 ] (Boreham et al, 2021b;Geymond et al, 2022;Moretti et al, 2022;Malvoisin and Brunet, 2023). Associated thermodynamic calculations at T < 200 °C showed that siderite could be the source of such emissions (Malvoisin and Brunet, 2023), which remains to be confirmed by further studies.…”

Section: Introductionmentioning

confidence: 98%

Reassessing the role of magnetite during natural hydrogen generation

et al. 2023

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Interactions between water and ferrous rocks are known to generate natural H2 in oceanic and continental domains via the oxidation of iron. Such generation has been mainly investigated through the alteration of Fe2+-silicate and some Fe2+-carbonates. So far, magnetite (α-Fe3O4) has never been considered as a potential source mineral for natural H2 since it is considered as a by-product of every known chemical reaction leading to the formation of H2, despite it bears 1/3 of Fe2+ in its mineral lattice. This iron oxide is rather seen as a good catalyst for the formation of H2. Recently, hydrogen emissions were observed in the surroundings of banded iron formations (BIF) that are constituted of, among other minerals, magnetite. Thus, this work is an attempt to constrain the true potential of magnetite by means of batch reactor experiments and additional thermodynamic calculations. It explores theoretical and experimental reaction pathways of magnetite during water-rock interactions, focusing on low temperatures (T < 200°C). For the purpose of the experiments, gold capsules filled with magnetite powders were run at 80°C and 200°C. Gas products were analyzed using gas chromatography (GC) while solid products were characterized by X-ray diffraction (XRD), Mössbauer spectroscopy, and scanning electron microscopy (SEM). After experimental alteration, high amounts of H2 were quantified while mineralogical transitions were observed by SEM. It showed self-reorganization of the primary iron oxide resulting in sharp-edge and better crystalized secondary minerals. In parallel, XRD analyses showed tiny changes between the patterns of the initial powder and the solid products of reaction. Finally, Mössbauer spectroscopy revealed that the starting magnetite was partly converted to maghemite (γ-Fe2O3), a metastable Fe-oxide only containing Fe3+. Major implications arise from these results. Concerning H2 exploration, this work provides evidence that natural hydrogen can be generated at near-ambient temperature. It also infers that magnetite-rich lithologies such as BIF should be targeted while looking for H2 source rocks. In addition, these outcomes could be of major interest for mining companies as they provide key elements to understand the formation of BIF-hosted iron ores.

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Micro Structured, Multipurpose Hydrogen Alarm Sensor System on Semiconductor Basis

Werner,

Prosposito,

Böhme

et al. 2024

Engineering Methodologies for Medicine and Sports

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Natural hydrogen emanations in Namibia: Field acquisition and vegetation indexes from multispectral satellite image analysis

Cited by 28 publications

References 63 publications

Natural hydrogen potential and basaltic alteration in the Asal–Ghoubbet rift, Republic of Djibouti

Natural hydrogen potential and basaltic alteration in the Asal–Ghoubbet rift, Republic of Djibouti

Reassessing the role of magnetite during natural hydrogen generation

Micro Structured, Multipurpose Hydrogen Alarm Sensor System on Semiconductor Basis

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