Origin of continuous hydrogen flux in gas manifestations at the Larderello geothermal field, Central Italy

Leila, Mahmoud; Lévy, Dan; Battani, A.; Piccardi, Luigi; Šegvić, Branimir; Badurina, Luka; Pasquet, Gabriel; Combaudon, Valentine; Moretti, Isabelle

doi:10.1016/j.chemgeo.2021.120564

Cited by 23 publications

(20 citation statements)

References 86 publications

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“…This late serpentinization, characterized by massive serpentine crosscutting type II ophicalcite, shows that deep or partially fresh peridotites could still be present and that ongoing serpentinization could be possible. This could result in ongoing H2 generation, similar to that observed in the Chimaera seeps (Etiope et al, 2011) or in Tuscany (Leila et al, 2021).…”

Section: Discussionsupporting

confidence: 60%

Successive phases of serpentinization and carbonation recorded in the Sivas ophiolite (Turkey), from oceanic crust accretion to post-obduction alteration

Lévy¹,

Callot²,

Moretti³

et al. 2022

BSGF - Earth Sci. Bull.

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The ophiolite of Sivas (Turkey) was studied in order to define the chronology of different alteration events related to a series of serpentinization and carbonation episodes. Six samples were investigated, representative of different types of ophicalcite (partially carbonated serpentinite). X-ray diffraction (XRD) and Mössbauer spectroscopy were used to determine the bulk mineralogy and the bulk Fe3+/Fetot ratio, respectively. Electron microprobe and secondary ion mass spectrometer (SIMS) analyses were also conducted to identify the chemical composition of different mineral phases in addition to the carbon and oxygen isotopic compositions of calcite. An initial, i.e. pre-obduction, phase of olivine and pyroxene serpentinization was followed by a brecciation event associated with precipitation of massive serpentine. This first alteration event occurred during exhumation of the peridotites to the ocean seafloor, followed by a carbonation event at temperatures in the range 35‒100°C. A low-temperature (~35°C) carbonation event occurred between 90 and 65 Ma. Finally, a reheating of the system likely occurred after the obduction at 55‒40 Ma, resulting in a carbonation episode followed by late serpentinization. Our study presents the first direct evidence of serpentinization after obduction. In that geological context, the hydrogen produced during the interpreted multiphase serpentinization may have been trapped by the salt deposits overlying the ophiolite but subsurface data will be necessary to define potential traps and reservoirs; further studies are also needed to determine whether the serpentinization process is still ongoing.

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Section: Discussionsupporting

confidence: 60%

Successive phases of serpentinization and carbonation recorded in the Sivas ophiolite (Turkey), from oceanic crust accretion to post-obduction alteration

Lévy¹,

Callot²,

Moretti³

et al. 2022

BSGF - Earth Sci. Bull.

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“…Coupling geothermal exploitation with H 2 exploration could thus present an opportunity for development and joint production. Indeed, H 2 has been described in onshore hightemperature geothermal fields, such as in Iceland and Larderello [45,102,118], and H 2 can be produced in conjunction with geothermal energy, using membrane systems for gas separation, where the flow rate and gas content are sufficiently high.…”

Section: Discussionmentioning

confidence: 99%

An Attempt to Study Natural H2 Resources across an Oceanic Ridge Penetrating a Continent: The Asal–Ghoubbet Rift (Republic of Djibouti)

et al. 2021

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Dihydrogen (H2) is generated by fluid–rock interactions along mid-ocean ridges (MORs) and was not, until recently, considered as a resource. However, in the context of worldwide efforts to decarbonize the energy mix, clean hydrogen is now highly sought after, and the production of natural H2 is considered to be a powerful alternative to electrolysis. The Afar Rift System has many geological features in common with MORs and offers potential in terms of natural H2 resources. Here, we present data acquired during initial exploration in this region. H2 contents in soil and within fumaroles were measured along a 200 km section across the Asal–Ghoubbet rift and the various intervening grabens, extending from Obock to Lake Abhe. These newly acquired data have been synthesized with existing data, including those from the geothermal prospect area of the Asal–Ghoubbet rift zone. Our results demonstrate that basalt alteration with oxidation of iron-rich facies and simultaneous reduction in water is the likely the source of the hydrogen, although H2S reduction cannot be ruled out. However, H2 volumes at the surface within fumaroles were found to be low, reaching only a few percent. These values are considerably lower than those found in MORs. This discrepancy may be attributed to bias introduced by surface sampling; for example, microorganisms may be preferentially consuming H2 near the surface in this environment. However, the low H2 generation rates found in the study area could also be due to a lack of reactants, such as fayalite (i.e., owing to the presence of low-olivine basalts with predominantly magnesian olivines), or to the limited volume and slow circulation of water. In future, access to additional subsurface data acquired through the ongoing geothermal drilling campaign will bring new insight to help answer these questions.

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“…Fischer-Tropsch-type synthesis, as low as 50°C, Sherwood Lollar et al 2002Lollar et al , 2006Lollar et al , 2008. Recent studies at a geothermal field in Italy conclude that hydrogen produced at deeper levels of the crust is abiotically consumed at high temperatures to form CH 4 (Leila et al 2021). Hydrogen can be biotically transformed to methane via methanogenesis.…”

Section: Characteristics Of Hydrogen Seepage Sitesmentioning

confidence: 99%

Natural hydrogen seeps as analogues to inform monitoring of engineered geological hydrogen storage

McMahon

Roberts

Johnson

et al. 2023

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Engineered geological porous media hydrogen storage must be designed to ensure secure storage, and use appropriate monitoring, measurement and verification tools. Here, we identify and characterize 60 natural hydrogen seeps as analogues for potential leakage from engineered storage reservoirs to consider implications for monitoring. We report and compare the geological and environmental setting; seepage mode (dry gas/associated with water); co-released gases; seep rates and areal fluxes; temporal variation; seep structure; gas source; and composition. Seep characteristics are determined by local geological and hydrological conditions, specifically whether hydrogen gas is seeping through soils and unconsolidated sediments, fractured bedrock or into water. Hydrogen is typically co-emitted with other gases (CO 2 , CH 4 , N 2 ) with CH 4 , the most common co-emitted gas. The structural controls on seep location and characteristics are similar between hydrogen and CO 2 seeps. However, compared to CO 2 , hydrogen is more readily dispersed when mixing with air and hydrogen is more prone to being consumed or transformed via biotic or abiotic reactions, and so the quantity of leaked hydrogen can be greatly attenuated before seeping. Monitoring approaches should therefore be tailored to the local geology and hydrological conditions, and monitoring approaches to detect hydrogen and associated gases would be appropriate.

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Origin of continuous hydrogen flux in gas manifestations at the Larderello geothermal field, Central Italy

Cited by 23 publications

References 86 publications

Successive phases of serpentinization and carbonation recorded in the Sivas ophiolite (Turkey), from oceanic crust accretion to post-obduction alteration

Successive phases of serpentinization and carbonation recorded in the Sivas ophiolite (Turkey), from oceanic crust accretion to post-obduction alteration

An Attempt to Study Natural H2 Resources across an Oceanic Ridge Penetrating a Continent: The Asal–Ghoubbet Rift (Republic of Djibouti)

Natural hydrogen seeps as analogues to inform monitoring of engineered geological hydrogen storage

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