Assessment of natural hydrogen systems in Western Australia

The discovery of a large accumulation of natural hydrogen in Mali has triggered the opportunity to search for hydrogen accumulations in other countries. The generation of hydrogen in Mali is linked to the presence of very old iron-rich basement rocks. Solid-liquid redox reactions between iron-rich minerals and groundwater are a possible source of H₂ in deep basement rocks. The hypothesis is that hydrogen degassing may result in the surface circular shallow depressions. The Archean iron-rich Yilgarn and Pilbara cratons that cover a vast area of Western Australia contain abundant iron-rich mafic-ultramafic rocks. The craton reveals many surficial circular depressions visible through satellite images. The area has abundant fault systems and is blanketed with Eocene sedimentary rocks containing high-quality reservoir rocks. All these characteristics appear to provide most of the required elements, such as a hydrogen source, migration pathway, and reservoir rock for a complete “Hydrogen System” to be developed in the area.     

Natural hydrogen seeps identified in the North Perth Basin,Western Australia

Natural hydrogen seeps called fairy circles have been identified in Mali, Brazil, Russia, and United-States. Natural hydrogen is produced from a field in Mali for 7 years. The natural hydrogen system is still poorly understood and needs to be studied in new geological contexts as to streamline hypotheses on the system dynamics and elements into concepts. In Australia, numerous circular surface features, commonly called salt lakes or swaps, are visible from the sky but no existing work shows nor quantifies any hydrogen content in those features. In this study, we reviewed the existing literature on fairy circles as to determine and directly test with soil-gas measurements if hydrogen surface-emitting features are present in Australia. We determined best candidates to test with a multi-disciplinary approach linking geology, multi-physical imaging, and seismic interpretation. Soil-gas measurements showed persistent hydrogen concentration localized in the external ring of circular depressions aligned along the Darling Fault, a major crustal boundary between the granitic, mafic and ultramafic rocks of the Yilgarn Craton from the sedimentary rocks of the Perth Basin. This work is the proof that fairy circles, in the meaning of H₂ emitting structures, are present in Australia and opens the door to new prospectivity pathways by evaluating original hypotheses on natural hydrogen generation, migration pathways and entrapment. This geological setting promotes deep serpentinization of ultramafic rocks as well as oxidation of iron-rich Archean rocks and mafic dikes as potential hydrogen sources that are both of massive potential economic value. This hydrogen can circulate and be entrapped as aqueous hydrogen in low-salinity aquifers or migrate in gaseous phase in fault zones up to intermediate structural reservoir or to the surface.     

Natural hydrogen continuous emission from sedimentary basins: The example of a Brazilian H2-emitting structure

Hydrogen escaping from sedimentary basins has already been described in various parts of the world. Some of these leakages have been identified by superficial circular depressions, also called “fairy circles”. Gas detection measurements, randomly repeated after a few months have shown that the amount of hydrogen present in soils is not constant neither versus time nor versus position in a given structure. Permanent monitoring gas analyzers were installed in the ground to estimate hydrogen flow outgassing from a topographical circular depression located in Brazil. Data show that a hydrogen flux occurs during the hottest moment of the day, as shown with permanent sensors set at a regular spacing. The process may look like a soil evaporation. In that same structure, other detectors show much higher and irregular gas output which present an unclear correlation as a function of ambient temperature and atmospheric pressure. The relationship with temperature suggests a role of water saturation driving the overall hydrogen fluxes. The reported geochemical data imply that (1) one measurement taken at a given hour on a structure cannot be considered as quantitative, as it varies too much with time and is also probably related to the soil perturbation induced by the shallow drilling, (2) hydrogen released through the soils of the studied structure is recharged daily, (3) hydrogen flux is high enough to reach the surface without being buffered by water or bacterial activity within the soil and (4) soil cannot be solely considered as a hydrogen sink but also, at least in some areas, as a hydrogen emitter. This appears to highlight that the subsurface may be considered in this site as a source of natural hydrogen, clearly differentiated from a biochemical system of atmospheric H₂ consumed by bacteria.     

In the path for creating Research-to-business new opportunities on green hydrogen between Italy and Brazil

On September 22, 2021, 5 experts from Brazil and 5 from Italy discussed the future of research-to-business (R2B) cooperation between Italy and Brazil on green hydrogen (H₂) and related technologies. The workshop discussed some priorities of the Brazilian policies and elucidated the strengths and the weaknesses of the biggest economy among the Latin American countries. Because of its territorial and underground resources its social and economic activities, Brazil offers an excellent basin for supporting an H₂-based economy. A well-established connection between Brazilian Universities and EU research organisations already exists in up-to-date research activities and frameworks for grants programmes. Nevertheless, Brazil has some difficulties creating new economies through the industrialisation of research achievements. On the other hand, Italy has a long tradition of creating and exporting technologies because its enterprises are generally prone to creating new business.In this communication, we reported the argued discussions between Brazilian and Italian players on green hydrogen that discussed how to improve the technological interaction between the two countries. This meeting discussed the entire value chain for green hydrogen, from the production to the end-user, and included distribution and commercialisation of green H₂ and related technologies.     

Modelling of hydrogen production from hydrogen sulfide in geothermal power plants

Geothermal power plants emit high amount of hydrogen sulfide (H₂S). The presence of H₂S in the air, water, soils and vegetation is one of the main environmental concerns for geothermal fields. There is an increasing interest in developing suitable methods and technologies to produce hydrogen from H₂S as promising alternative solution for energy requirements. In the present study, the AMIS technology is the invention of a proprietary technology (AMIS^® - acronym for “Abatement of Mercury and Hydrogen Sulfide” in Italian language) for the abatement of hydrogen sulphide and mercury emission, is primarily employed to produce hydrogen from H₂S. A proton exchange membrane (PEM) electrolyzer operates at 150 °C with gaseous H₂S sulfur dimer in the anode compartment and hydrogen gas in the cathode compartment. Thermodynamic calculations of electrolysis process are made and parametric studies are undertaken by changing several parameters of the process. Also, energy and exergy efficiencies of the process are calculated as % 27.8 and % 57.1 at 150 °C inlet temperature of H₂S, respectively.     

Massive release of natural hydrogen from a geological seep (Chimaera,Turkey): Gas advection as a proxy of subsurface gas migration and pressurised accumulations

Subsurface geological reservoirs of natural hydrogen gas (H₂), a clean fuel and energy vector, are currently a target for energy resource exploration. Such reservoirs can be revealed by the presence of H₂ within soil, analogous to hydrocarbon seepage in petroleum systems. Nevertheless, defining the level of soil H₂ that can indicate a potentially economic resource is currently impossible, and identifying geological H₂ within soil-gas is challenging because H₂ concentrations and the isotopic composition (δ²H) may overlap with the in-situ biological signature. In spite of these limitations, analogies to conventional hydrocarbon systems suggest that the presence of surface advective gas flows can reveal (unlike diffusion) a subsoil source and even pressurised gas accumulations of H₂. Here, a massive release of H₂ is reported from a CH₄–H₂ rich seep in Turkey, known as Chimaera, an emblematic example of H₂ advection. The site represents the first case where a closed-chamber flux method was applied for H₂ seepage. H₂ advection at the site was clearly indicated by numerous gas vents and flames, and by the heterogeneous spatial distribution of pervasive, invisible exhalation (miniseepage), inducing rapid H₂ concentration build-up within the chamber. H₂ emission (～10 ± 3 kg day^?1, with the highest H₂ emission factor reported, thus far, of ～5000 kg km^?2 day^?1) is continuous and long lasting (flames have been documented for millennia) and, using an analogy for hydrocarbon seeps, may stem from pressurised accumulations. The Chimaera case is illustrative of how detecting soil H₂ advection may help unravel surface (biological) vs. subsoil (geological) gas origins in cases where, in the absence of significant gas seepage, soil H₂ concentrations are within the range of biological production (10⁰-10³ ppmv, e.g., as for “fairy circles” observed in several countries). Interpretations must, however, be supported by additional geochemical data and evaluations of potential biological H₂ production within the surface ecosystem.     

Some considerations of the lean flammability limits of mixtures involving hydrogen

Consistent data regarding the flammability limits of homogeneous mixtures of hydrogen gas in air at atmospheric pressure are presented for various temperatures extending down to ?130 °C. The retardation of the combustion of lean homogeneous mixtures of hydrogen and air due to the homogeneous mixing of inerts such as CO₂, N₂ and He is also considered. Moreover, the enhancement of the flammability limits of fuel mixtures involving CO, CH₄, C₃H₈ and C₂H₄ in air due to the presence of some hydrogen is also presented. Guidelines are then suggested for predicting the role of the presence of hydrogen in the fuel-air mixtures over a wide range of concentrations and temperatures.     

H2 permeation and its influence on gases through a SAPO-34 zeolite membrane

This work analysed the permeation of binary and ternary H₂-containing mixtures through a SAPO-34 membrane, aiming at investigating how hydrogen influences and its permeation is influenced by the presence of the other gaseous species, such as CO₂ and CH₄. We considered the behaviour of various gas mixtures in terms of permeability and selectivity at various temperatures (25–300 °C), feed pressures (400–1000 kPa) and compositions by means of an already validated mass transport model, which is based on surface and gas translation diffusion. We found that the presence of CO₂ and CH₄ in the H₂-containing mixtures influences in a similar way the H₂ permeation, reducing its permeability of about 80% compared to the single-gas value because of their stronger adsorption. On the other hand, H₂ promotes the permeation of CO₂ and CH₄, causing an increment of their permeability with respect to those as single gases. These combined effects reflected in interesting selectivity values in binary mixture (e.g., CO₂/H₂ about 11 at 25 °C, H₂/CH₄ about 9 at 180 °C), which showed the potential of SAPO-34 membranes in treating of H₂-containing mixtures.     

Influence of capillary threshold pressure and injection well location on the dynamic CO2 and H2 storage capacity for the deep geological structure

The subject of this study is the analysis of influence of capillary threshold pressure and injection well location on the dynamic CO₂ and H₂ storage capacity for the Lower Jurassic reservoir of the Sierpc structure from central Poland. The results of injection modeling allowed us to compare the amount of CO₂ and H₂ that the considered structure can store safely over a given time interval. The modeling was performed using a single well for 30 different locations, considering that the minimum capillary pressure of the cap rock and the fracturing pressure should not be exceeded for each gas separately.Other values of capillary threshold pressure for CO₂ and H₂ significantly affect the amount of a given gas that can be injected into the reservoir. The structure under consideration can store approximately 1 Mt CO₂ in 31 years, while in the case of H₂ it is slightly above 4000 tons. The determined CO₂ storage capacity is limited; the structure seems to be more prospective for underground H₂ storage. The CO₂ and H₂ dynamic storage capacity maps are an important element of the analysis of the use of gas storage structures. A much higher fingering effect was observed for H₂ than for CO₂, which may affect the withdrawal of hydrogen. It is recommended to determine the optimum storage depth, particularly for hydrogen. The presented results, important for the assessment of the capacity of geological structures, also relate to the safety of use of CO₂ and H₂ underground storage space.     

Complex interaction of hydrogen with the monolayer TiS2 decorated with Li and Li2O clusters: an ab initio random structure searching approach

We have applied ab initio random structure searching to study the structure, stability and hydrogen storage properties of monolayer TiS₂ coated with Li and small Li₂O clusters. For the low Li covered system we found a complex adsorption mechanism: some hydrogen molecules were adsorbed due to polarization with Li, others due to polarization with S near the surface of TiS₂. The peculiarities of the interaction of the H₂ molecules with each other and the preferred adsorption sites allowed us to formulate a series of recommendations that can be useful when selecting the material for the most effective support. Moreover, the findings also show that the storage capacity of this system can reach up to 9.63 wt%, presenting a good potential as hydrogen storage material. As for the Li₂O clusters supported on TiS₂, we found that the polarization of the Li–O bond increases upon the adsorption of the Li₂O nanocluster. Moreover, the polarized Li–S bonds appear in addition to the already existing Li–O bonds. All this is possible due to the extraction of 1.46 electrons from the S atom of the substrate by O atom of the cluster, and should contribute to an increase in both the adsorption energy and the maximum capacity. The adsorption energies of H₂ for the systems studied here are within 0.11–0.16 eV/H₂ which is a recommended range for reversible hydrogen physisorption under standard test conditions. This study may stimulate experimental efforts to check the claims of high-capacity, stable and reversible hydrogen adsorption reported here.     

An ab-initio study of hydrogen storage performance of Si2BN nanotubes decorated with group 8B transition metals

Binding of group 8B transition metals (TMs) on Si₂BN nanotubes and the adsorption of H₂ molecules on TM-decorated Si₂BN nanotubes are investigated in the framework of first principles-based density functional theory (DFT). Our results show the adsorption energy of H₂ molecule on TM-decorated Si₂BN nanotube (−2.57 eV) to be greater than those of the other reported adsorbents. The enhancement of the adsorption property is attributed to the structural deformation and the induced charge transfer between TM–decorated Si₂BN nanotube and the hydrogen molecule. Our findings reveal the TM–decorated Si₂BN nanotubes to be highly sensitive to the presence of H₂ molecules. Additionally, we also investigated the adsorption process of multiple H₂ molecules on TM-decorated Si₂BN nanotubes. Our observations lead us to surmise that the maximum storage number of H₂ molecules adsorbed over the TM-decorated Si₂BN nanotubes is four. These results suggest useful potential for the TM-decorated Si₂BN nanotube to be considered as an appropriate medium for hydrogen storage.     

A correct perspective for hydrogen from engineered diagenesis

Wind and solar photovoltaic electricity production have already reached very low levels of levelized cost of energy (LCOE). Electrolyzers have already reached high efficiencies which are further improving, while costs are dramatically reducing. They are commercial products. Green hydrogen (H₂) is the product of excess wind and solar electricity, specifically electricity that will be otherwise wasted, without the huge energy storage needed presently almost completely missing. By growing the installed capacity of wind and solar power plants, there will be a non-dispatchable production by wind and solar more often in excess, but sometimes also in defect, of the grid demand, in presence of limited energy storage. H₂ is one of the key energy storage technologies needed to ensure grid stability. Production of H₂ above what is needed to stabilize the grid significantly helps in applications such as land, and sea but especially air transport where the storage of energy onboard in a fuel is preferable to the storage of energy as electricity into a battery. The engineered diagenesis for H₂ is unlikely better than green hH₂. Apart from being a nice idea to be proven workable, with a technology readiness level (TRL) presently of zero, and thus impossible to be objectively compared with commercial products, the engineered diagenesis for H₂, even if possible, also does not help with non-dispatchable renewable energy production. The concept may also have negative environmental aspects similar to fracking which have not been considered yet, and also bear huge economic costs in addition to environmental. Here we review the pros and cons of this novel technology, which once proven workable, which is not the case yet, should be considered as a possible way to complement rather than replace green H₂ production.     

Thermodynamic analysis of a novel solar and geothermal based combined energy system for hydrogen production

The present study develops a new solar and geothermal based integrated system, comprising absorption cooling system, organic Rankine cycle (ORC), a solar-driven system and hydrogen production units. The system is designed to generate six outputs namely, power, cooling, heating, drying air, hydrogen and domestic hot water. Geothermal power plants emit high amount of hydrogen sulfide (H₂S). The presence of H₂S in the air, water, soils and vegetation is one of the main environmental concerns for geothermal fields. In this paper, AMIS(AMIS® - acronym for “Abatement of Mercury and Hydrogen Sulphide” in Italian language) technology is used for abatement of mercury and producing of hydrogen from H₂S. The present system is assessed both energetically and exergetically. In addition, the energetic and exergetic efficiencies and exergy destruction rates for the whole system and its parts are defined. The highest overall energy and exergy efficiencies are calculated to be 78.37% and 58.40% in the storing period, respectively. Furthermore, the effects of changing various system parameters on the energy and exergy efficiencies of the overall system and its subsystems are examined accordingly.     

Influence of hydrogen dilution on low-temperature polycrystalline silicon formation using RF excitation SiH4/H2 plasma

The effect of hydrogen dilution was investigated on polycrystalline silicon formation using radio frequency excitation SiH₄/ H₂ plasma. The hydrogen dilution reduces the growth rate of the a-Si : H films. The dark conductivity of the a-Si : H films increases with increasing H₂ dilution. The dark conductivity of the poly-Si films formed by recrystallization annealing of the a-Si : H film decrease with H₂ dilution. The grain size, with X-ray diffraction spectroscopy and scanning electron microscopy images of the poly-Si films, is in reverse ratio to the H₂ dilution.     

A mathematical,economic and energetic appraisal of biomethane and biohydrogen production from Brazilian ethanol plants' waste: Towards a circular and renewable energy development

The high production of sugarcane in Brazil and its application of ethanol and sugar production results in a higher generation of vinasse and bagasse. The treatment of these residues can be carried out using anaerobic co-digestion procedures. Besides promoting waste treatment, it enables energy exploration through biogas and hydrogen generation. Bioenergy use can also generate steam in sugar and alcohol plants by burning, sugarcane milling, fueling vehicles for the transport of products, among others. These energy applications allow total and efficient, energetic exploring of sugarcane. Hence, this study estimated the production of methane, hydrogen, thermal and electrical energy generated from vinasse and bagasse in the autonomous and annexed Brazilian ethanol and sugar plants. Three scenarios present the use of biogas generated: Scenario 1: energy use of all methane from biogas; Scenario 2: hydrogen production from the remaining methane, after considering the energy autonomy of the ethanol plants; Scenario 3: hydrogen production from all the methane generated. All the scenarios which considered the use of methane led to energy self-sufficiency in the sector. However, only annexed plants present economic feasibility for implementing the project. Scenario 2 is highlighted in this study, once beyond the sector's energetic self-sufficiency, the operational conditions enabled the storage of 9.26E+07 Nm³.d^?1 of hydrogen, equal 3.04E+08 ton per year. CH₄ and H₂ production seen in a global scenario of circular economy and energy security have high benefits, contributing to the gradual transformation of an economy dependent on non-renewable resources into a circular and renewable economy.     

A first principles study of hydrogen storage in lithium decorated defective phosphorene

In this study, we studied defect-engineering and lithium decoration of 2D phosphorene for effective hydrogen storage using density functional theory. Contrary to graphene, it is found that the presence of point-defects is not preferable for anchoring of H₂ molecules over defective phosphorene. According to previous research, strategies such as defect engineering, metal decoration, and doping enhance the hydrogen storage capacity of several 2D materials. Our DFT simulations show that point defects in phosphorene do not improve the hydrogen storage capacity compared to pristine phosphorene. However, selective lithium decoration over the defective site significantly improves the hydrogen adsorption capacity yielding a binding energy of as high as ?0.48 eV/H₂ in Li-decorated single vacancy phosphorene. Differential charge densities and projected density of states have been computed to understand the interactions and charge transfer among the constituent atoms. Strong polarization of the H₂ molecule is evidenced by the charge accumulation and depletion. The PDOS shows that the presence of Li leads to enhanced charge transfer. The maximum gravimetric density was investigated by sequentially adding H₂ molecules to the Li-decorated single vacancy defective phosphorene. The Li-decorated single vacancy phosphorene is found to possess a gravimetric density of around 5.3% for hydrogen storage.     

Blue hydrogen can be a source of green energy in the period of decarbonization

The most troublesome problems in making blue hydrogen are fugitive emissions of methane in extraction, transportation, and in converting methane to hydrogen by the SMR-WGS-PSA that needs burning methane to provide endothermic heat. The solution is to generate blue hydrogen on the extraction site and use a part of the hydrogen to make electricity on site by a hydrogen fuel cell that also provides steam and heat and eliminates H₂ burning. CO₂ emissions are sequestered by pushing the gas into geological formations from which fossil gas was extracted. Another alternative is to use a half of the produced H₂ to make ammonia on-site by the Haber- Bosh process along with the electricity by the hydrogen fuel cell that also provides concentrated nitrogen from air used to oxidize hydrogen. Turquoise hydrogen conversion wherein high heat or plasma converts methane to CO_x free hydrogen is promising and produces valuable solid carbon and graphene byproducts.     

Toluene hydrogenation over Pd and Pt catalysts as a model hydrogen storage process using low grade hydrogen containing catalyst inhibitors

The effects of CO and H₂S as catalyst inhibitors on the rate of toluene hydrogenation were studied as a means of hydrogen storage using low-grade hydrogen. Pd/SiO₂ suffered serious negative effects from catalyst inhibitors; however, Pd/TiO₂–SiO₂ exhibited high CO and H₂S tolerance because the acidic support decreased the electron density of the Pd metal particles, which, in turn, decreased the interaction between the Pd surface and CO (or H₂S). The TiO₂–SiO₂-supported Pd catalyst exhibited activity greater than that of the TiO₂–SiO₂-supported Pt catalyst in the presence of CO; however, it exhibited lower activity in presence of H₂S. Catalyst characterization after sulfidation with H₂S revealed that Pd particles were fully sulfided, whereas Pt particles were sulfided only on their surface. We concluded that Pd catalysts supported on acidic oxides exhibit excellent activity toward toluene hydrogenation in the presence of CO and that Pt catalysts exhibit excellent activity in the presence of H₂S.     

The potential and economic viability of hydrogen production from the use of hydroelectric and wind farms surplus energy in Brazil: A national and pioneering analysis

Energy security is an issue at stake in governments all over the world, and also in Brazil. Although the country's energetic matrix is largely based on hydropower sources, the need for diversification is increasingly needed. The possibility of hybrids between hydropower and wind power for hydrogen production emerges as a clean alternative source for energy security. In high-throughput seasons, excess energy could be used to produce hydrogen, which could supply shortages of energy. This study shows the potential for producing hydrogen in Brazil, using excess energy from hydroelectric and wind farms. Taking into account one hour per day of surplus energy production, it would be possible to generate 6.50E+09 Nm³.y⁻¹ of H₂. On the other hand, considering two and three hours, the H₂ generation would be equal to 1.30E+10 Nm³.y⁻¹ and 2.00E+10 Nm³.y⁻¹, respectively. This study calculated the economic viability for hydrogen production, at a cost of 0.303 USD.kWh⁻¹, a higher cost if compared to that of the wind and hydroelectric plants.