Hydrogen Reservoir Research Articles

Pressure transient analysis for asymmetrically fractured wells in dual-permeability organic compound reservoir of hydrogen and carbon

In this paper, a comprehensive semi-analytical model was presented to investigate pressure transient behavior for asymmetrically fractured wells in organic compound reservoir of hydrogen and carbon with dual-permeability behavior. Stehfest inversion algorithm can be used to transform it back into time domain to obtain pressure solution. The presented solution was validated well with numerical solutions. Flow characteristics for asymmetrically fractured wells in dual-permeability organic compound reservoir of hydrogen and carbon were divided into five regime. The effects of some important parameters on dimensionless pressure and its derivative curves were analyzed in details, including inter-porosity flow coefficient from matrix to natural fractures λ, storage coefficient ω, fracture asymmetry factor θ and permeability ratio κ. The presented model can be used to predict production performance and do well test analysis in the development of dual-permeability organic compound reservoir of hydrogen and carbon.

An innovative technology of directional propagation of hydraulic fracture guided by radial holes in fossil hydrogen energy development

Conventional hydraulic fracturing fails to develop low permeability reservoirs of fossil hydrogen energy that are not located in the direction of maximum principal in-situ stress. A new technology of fracture propagation guided by radial holes is proposed, which can realize directional propagation of hydraulic fracture along radial holes in fossil hydrogen energy development. In order to verify this new technology, a model of radial holes combined with hydraulic fracturing is established by the ABAQUS extended finite element method. Simulation results show that radial holes play a guiding role in fractures propagation. The influence extent of seven factors on the directional propagation of hydraulic fracture is listed as follows (from strong to weak): azimuth of radial holes > horizontal in-situ stress difference of fossil hydrogen reservoir > injection rate of fracturing fluid > Young's modulus of rock > permeability of fossil hydrogen reservoir > Poisson ratio of rock > viscosity of fracturing fluid. True tri-axial experiment is carried out to verify the accuracy of numerical simulation, and the result is consistent with numerical model, which indicates that numerical simulation is reliable.

PV with multiple storage as function of geolocation

A real PV array combined with two storage solutions (B, battery, and H, hydrogen reservoir with electrolyzer-fuel cells) is modeled in two geolocations: Oxford, UK, and San Diego, California. All systems meet the same 1-year, real domestic demand. Systems are first configured as standalone (SA) and then as Grid-connected (GC), receiving 50% of the yearly-integrated demand. H and PV are dynamically sized as function of geolocation, battery size BM and H’s round-trip efficiency ηH.For a reference system with battery capacity BM=10 kW h and ηH=0.4, the required H capacity in the SA case is ∼1230 kW h in Oxford and ∼750 kW h in San Diego (respectively, ∼830 kW h and ∼600 kW h in the GC case). Related array sizes are 93% and 51% of the reference 8 kWp system (51% and 28% for GC systems). A trade-off between PV size and battery capacity exists: the former grows significantly as the latter shrinks below 10 kW h, while is insensitive for BM rising above it. Such a capacity achieves timescales’ separation: B, costly and efficient, is mainly used for frequent transactions (daily periodicity or less); cheap, inefficient H for seasonal storage instead.With current PV and B costs, the SA reference system in San Diego can stay within 2·104 $ CapEx if H’s cost does not exceed ∼7 $/kW h; this figure increases to 15 $/kWh with Grid constantly/randomly supplying a half of yearly energy (6.5 $/kWh in Oxford, where no SA system is found below 2·104 $ CapEx).Rescaling San Diego’s array (further from its optimal configuration than Oxford’s) to the ratio between local, global horizontal irradiance (GHI) and Oxford GHI, yields in all cases a 11% reduction of size and corresponding cost, with the other model outputs unaffected. The location dependent results vary to different extents when extending the modeled timeframe to 18 years. In any case, the variability stays within ±10% of the reference year.

On the Role of Dissolved Gases in the Atmosphere Retention of Low-mass Low-density Planets

Abstract Low-mass low-density planets discovered by Kepler in the super-Earth mass regime typically have large radii for their inferred masses, implying the presence of H2–He atmospheres. These planets are vulnerable to atmospheric mass loss due to heating by the parent star’s XUV flux. Models coupling atmospheric mass loss with thermal evolution predicted a bimodal distribution of planetary radii, which has gained observational support. However, a key component that has been ignored in previous studies is the dissolution of these gases into the molten core of rock and iron that constitute most of their mass. Such planets have high temperatures (>2000 K) and pressures (∼kbars) at the core-envelope boundary, ensuring a molten surface and a subsurface reservoir of hydrogen that can be 5–10 times larger than the atmosphere. This study bridges this gap by coupling the thermal evolution of the planet and the mass loss of the atmosphere with the thermodynamic equilibrium between the dissolved H2 and the atmospheric H2 (Henry’s law). Dissolution in the interior allows a planet to build a larger hydrogen repository during the planet formation stage. We show that the dissolved hydrogen outgasses to buffer atmospheric mass loss. The slow cooling of the planet also leads to outgassing because solubility decreases with decreasing temperature. Dissolution of hydrogen in the interior therefore increases the atmosphere retention ability of super-Earths. The study highlights the importance of including the temperature- and pressure-dependent solubility of gases in magma oceans and coupling outgassing to planetary evolution models.

Hydrogen escape from Mars enhanced by deep convection in dust storms

Present-day water loss from Mars provides insight into Mars’s past habitability1–3. Its main mechanism is thought to be Jeans escape of a steady hydrogen reservoir sourced from odd-oxygen reactions with near-surface water vapour2, 4,5. The observed escape rate, however, is strongly variable and correlates poorly with solar extreme-ultraviolet radiation flux6–8, which was predicted to modulate escape 9 . This variability has recently been attributed to hydrogen sourced from photolysed middle atmospheric water vapour 10 , whose vertical and seasonal distribution is only partly characterized and understood11–13. Here, we report multi-annual observational estimates of water content and dust and water transport to the middle atmosphere from Mars Climate Sounder data. We provide strong evidence that the transport of water vapour and ice to the middle atmosphere by deep convection in Martian dust storms can enhance hydrogen escape. Planet-encircling dust storms can raise the effective hygropause (where water content rapidly decreases to effectively zero) from 50 to 80 km above the areoid (the reference equipotential surface). Smaller dust storms contribute to an annual mode in water content at 40−50 km that may explain seasonal variability in escape. Our results imply that Martian atmospheric chemistry and evolution can be strongly affected by the meteorology of the lower and middle atmosphere of Mars. Mars Climate Sounder’s multi-annual observations of the vertical distribution of water and dust in the Martian atmosphere show that deep convection from dust storms transports water from the lower to the middle atmosphere, enhancing water loss to space.

Selective photocatalytic CO2 reduction to CH4 over Pt/In2O3: Significant role of hydrogen adatom

The selectivity of photocatalytic CO2 reduction to CH4 can be enhanced over Pt-decorated semiconductors, which is commonly attributed to the fact that a Schottky junction is formed, thus enhancing photoinduced electron lifetime. However, it is difficult to understand why the yield of CO—the other product of photocatalytic CO2 reduction—is decreased only in terms of photoinduced electron lifetime. In this work, the mechanism of Pt-promoted CH4 formation was probed again in a gas-solid system of photocatalytic CO2 reduction over highly-dispersed-Pt decorated In2O3 nanorods (Pt/In2O3). It was found that the presence of Pt modulates the surface property of In2O3 due to electronic and steric effect, resulting in a loss of HCO3−, b-CO32− and m-CO32− species for the coadsorption of CO2 with H2O. However, this is not directly related with the high CH4 selectivity and low CO yield on the Pt/In2O3 photocatalysts. Photocatalytic reductions of CO, HCOOH, CH2O, and CH3OH as well as photocatalytic CO2 reduction over photocatalysts with different H2 uptakes confirm that H adatoms derived from H2 or H2O dissociation on Pt play a key role in the formation of CH4. Low H2 dissociation barrier on Pt and weak HPt bond facilitate the bonding of C in CO2 with H, thus restraining CO production. In other words, the metallic Pt acts as atomic hydrogen reservoir that supplies sufficient and readily available protons for CH4 formation over Pt-decorated semiconductors. The present work offers a new window to explore non-noble metals or their alloys with stability in air and high dissociation ability to H2 or H2O as a replacement of Pt for CO2 photoreduction to CH4.

A new approach to optimize the performance of a hydrogen reservoir using activated carbon as the storing material

We have developed a new approach in order to compute the optimal way of filling as efficiently as possible an hydrogen reservoir using activated carbon as the storing material. Our approach combines finite element computation with multi objective optimization techniques based on the Fast Pareto Genetic Algorithm (FPGA) to find an ensemble of optimal solutions known as the Pareto front. We have illustrated our method by studying a small cylindrical reservoir. We were able to find a 7-point filling function (i.e. the input flow as a function of time) giving the shortest filling time to reach a stored hydrogen mass for a given heat transfer coefficient while keeping the reservoir internal temperature and pressure under their maximal safe values.

Coupling of Crumpled-Type Novel MoS2 with CeO2 Nanoparticles: A Noble-Metal-Free p-n Heterojunction Composite for Visible Light Photocatalytic H2 Production.

In terms of solar hydrogen production, semiconductor-based photocatalysts via p–n heterojunctions play a key role in enhancing future hydrogen reservoir. The present work focuses on the successful synthesis and characterization of a novel p-MoS2/n-CeO2 heterojunction photocatalyst for excellent performance toward solar hydrogen production. The synthesis involves a simple in situ hydrothermal process by varying the wt % of MoS2. The various characterization techniques support the uniform distribution of CeO2 on the surface of crumpled MoS2 nanosheets, and the formation of p–n heterojunction is further confirmed by transmission electron microscopy and Mott–Schottky analysis. Throughout the experiment, it is demonstrated that 2 wt % MoS2 in the MoS2/CeO2 heterojunction photocatalyst exhibits the highest rate of hydrogen evolution with a photocurrent density of 721 μA cm–2. The enhanced photocatalytic activity is ascribed to the formation of the p–n heterojunction that provides an internal electric field to facilitate the photogenerated charge separation and transfer.

Martian low-temperature alteration materials in shock-melt pockets in Tissint: Constraints on their preservation in shergottite meteorites

We apply an array of in situ analytical techniques, including electron and Raman microscopy, electron and ion probe microanalysis, and laser ablation mass spectrometry to the Tissint martian meteorite in order to find and elucidate a geochemical signature characteristic of low-temperature alteration at or near the martian surface. Tissint contains abundant shock-produced quench-crystallized melt pockets containing water in concentrations ranging from 73 to 1730ppm; water content is positively correlated with Cl content. The isotopic composition of hydrogen in the shock-produced glass ranges from δD=2559 to 4422‰. Water is derived from two distinct hydrogen reservoirs: the martian near-surface (>500‰) and the martian mantle (−100‰). In one shock melt pocket comprising texturally homogeneous vesiculated glass, the concentration of H in the shock melt decreases while simultaneously becoming enriched in D, attributable to the preferential loss of H over D to the vesicle while the pocket was still molten. While igneous sulfides are pyrrhotite in composition (Fe0.88-0.90S), the iron to sulfur ratios of spherules in shock melt pockets are elevated, up to Fe1.70S, which we attribute to shock-oxidation of igneous pyrrhotite and the formation of hematite at high temperature. The D- and Cl-enrichment, and higher oxidation of the pockets (as indicated by hematite) support a scenario in which alteration products formed within fractures or void spaces within the rock; the signature of these alteration products is preserved within shock melt (now glass) which formed upon collapse of these fractures and voids during impact shock. Thermal modeling of Tissint shock melt pockets using the HEAT program demonstrates that the shock melt pockets with the greatest potential to preserve a signature of aqueous alteration are small, isolated from other regions of shock melt, vesicle-free, and glassy.

Global hydrogen reservoirs in basement and basins

BackgroundHydrogen is known to occur in the groundwaters of some ancient cratons. Where associated gases have been dated, their age extends up to a billion years, and the hydrogen is assumed also to be very old. These observations are interpreted to represent the radiolysis of water and hydration reactions and migration of hydrogen into fracture systems. A hitherto untested implication is that the overwhelming bulk of the ancient low-permeability basement, which is not adjacent to cross-cutting fractures, constitutes a reservoir for hydrogen.ResultsNew data obtained from cold crushing to liberate volatiles from fluid inclusions confirm that granites and gneiss of Archean and Palaeoproterozoic (>1600 Ma) age typically contain an order of magnitude greater hydrogen in their entrained fluid than very young (<200 Ma) granites. Sedimentary rocks containing clasts of old basement also include a greater proportion of hydrogen than the young granites.ConclusionsThe data support the case for a global reservoir of hydrogen in both the ancient basement and in the extensive derived sediments. These reservoirs are susceptible to the release of hydrogen through a variety of mechanisms, including deformation, attrition to reduce grain size and diagenetic alteration, thereby contributing to the hydrogen required by chemolithoautotrophs in the deep biosphere.

Mitigation strategies for hydrogen starvation under dynamic loading in proton exchange membrane fuel cells

Hydrogen starvation in a proton exchange membrane (PEM) fuel cell during dynamic loading can have detrimental effects to cell performance, causing significant degradations to cell components and reduce stack durability. In this study, mitigation strategies for hydrogen starvation are proposed and effectiveness of the approaches is studied by measuring variations of local current densities and temperatures in situ under various load change scenarios. A two-step startup strategy is studied and the experimental results show that current undershoots in the downstream and the region with zero current at the outlet can be completely eliminated. Experimental studies have also been conducted to examine the effectiveness of a hydrogen reservoir at the anode outlet and the results show that it can significantly reduce the fluctuations in both local current densities and temperatures under both potentiostatic and galvanostatic modes.

Water-mediated NOE: a promising tool for interrogating interfacial clay\u2013xenobiotic interactions

BackgroundThe sorption of anthropogenic compounds on clay minerals is a complex molecular process with important implications for the fate of agrochemicals and organic pollutants in the environment.ResultsThe present study illustrates the use of a water-mediated NOE approach to study clay binding interactions. This method exploits the interfacial water layer on clay surfaces as a hydrogen reservoir for magnetization transfer. The interactions of four different xenobiotics with clay suspension were investigated through this method to demonstrate its capability to screen for the clay–xenobiotic molecular affinity. Further, based on the NOE build-up rates, epitope map of clay–xenobiotic interactions can be generated, explaining the orientation and mechanism of the interactions.ConclusionsThe water-mediated NOE approach has the potential to reveal key insights into the role that interfacial water plays in the binding process, providing a better understanding of the partitioning of anthropogenic compounds from bulk water into aqueous clay suspensions.Graphical abstract.

Characterization of spin-coated gallium oxide films and application as surface passivation layer on silicon

Gallium oxide films have shown a great potential as passivation layers on silicon solar cells. In this work, we employed the spin-coating method to form gallium oxide films on p-type silicon substrate as a surface passivation layer. The dependences of the structure and the surface passivation effect of the gallium oxide films on the annealing temperatures were investigated. Both Ga 3d and 2p 3/2 regions were also measured by X-ray photoelectron spectroscopy analysis to obtain the complementary information on the composition of the Ga2O3 films (versus depth). In addition, the Qeff polarity change and a C-V clockwise hysteresis of Ga2O3 passivated samples were also discussed in this study. The gallium oxide films underwent an amorphous-to-crystalline phase transformations as the annealing temperature was increased above 550 °C. With an annealing temperature increased from 450 to 850 °C, the thickness of an interfacial silicon oxide layer increased from 2 to 7.4 nm; the interface state density, Dit, decreased from 4.21 × 1011 to 1.53 × 1011 eV−1 cm−2 and the effective oxide charge density, Qeff, changed from −3.7 × 1010 to 1.1 × 1011 cm−2 respectively. The Dit dominated the films passivation effect of the gallium oxide films with increasing annealing temperatures. The residual gallium hydroxide can act as a hydrogen reservoir for hydrogen diffusion and the interface hydrogenation play an important role in the Dit decrease.

MASS MEASUREMENTS IN PROTOPLANETARY DISKS FROM HYDROGEN DEUTERIDE

ABSTRACT The total gas mass of a protoplanetary disk is a fundamental, but poorly determined, quantity. A new technique has been demonstrated to assess directly the bulk molecular gas reservoir of molecular hydrogen using the HD J = 1–0 line at 112 μm. In this work we present a Herschel Space Observatory 10 survey of six additional T Tauri disks in the HD line. Line emission is detected at &gt;3σ significance in two cases: DM Tau and GM Aur. For the other four disks, we establish upper limits to the line flux. Using detailed disk structure and ray-tracing models, we calculate the temperature structure and dust mass from modeling the observed spectral energy distributions, and we include the effect of UV gas heating to determine the amount of gas required to fit the HD line. The ranges of gas masses are 1.0–4.7 × 10−2 for DM Tau and 2.5–20.4 × 10−2 for GM Aur. These values are larger than those found using CO for GM Aur, while the CO-derived gas mass for DM Tau is consistent with the lower end of our mass range. This suggests a CO chemical depletion from the gas phase of up to a factor of five for DM Tau and up to two orders of magnitude for GM Aur. We discuss how future analysis can narrow the mass ranges further.

Spontaneous Hydrogen and Electricity Production in a Nested Carbon Fuel Cell

Introduction Hydrogen is a desirable fuel because it is an effective energy carrier and because it has minimal impact on the environment. However, there are no natural reservoirs of hydrogen, and the majority of hydrogen currently used needs to be produced either from steam reforming of hydrocarbons or electrolysis of water. Both of these methods are energy intensive and have significant drawbacks. Hydrogen from steam reforming of hydrocarbons contains trace amounts of CO that acts as a poison for the Pt catalyst in PEM fuel cells, and hence limits the usability of the hydrogen produced. Similarly, electrolysis of water is an electrochemically uphill process, which requires significant energy input. The steam-carbon-air fuel cell (SCAFC) concept is a viable alternative that is capable of producing carbon-free hydrogen and electricity spontaneously and at high primary efficiency. The SCAFC couples an air-carbon fuel cell [1] with a steam-carbon fuel cell [2] through a shared carbon bed at the anode, as shown in Figure 1. Both cells employ an ionically conducting and electrically insulating ceramic electrolyte membrane for selective transport of oxide ions from the cathode to the anode. While both the air-carbon and the steam-carbon cells are spontaneous (i.e., downhill in electrochemical potential), the steam-carbon cell is endothermic, while the air-carbon is highly exothermic. By coupling the air-carbon with the steam-carbon cell, the SCAFC achieves a novel device that produces both hydrogen and electricity spontaneously without the need for external heat or power input. This presentation builds upon modeling and experimental studies of both types of carbon fuel cells conducted in our laboratory [1-3] and describes how this novel idea can achieve efficient and clean production of hydrogen from solid carbonaceous fuels. Modeling of the Steam-Carbon-Air Fuel Cell A model of a SCAFC has been developed that takes into account reaction chemistry in the carbon bed, electrochemistry at the electrodes, mass transport of gases, and heat transfer. In the anode chamber, the carbonaceous fuel undergoes dry gasification via the reverse Boudouard reaction, forming CO that gets oxidized at the anode surfaces. The CO2 formed on the anode surfaces can then once again gasify the adjacent carbon, thus forming a self-sustained “CO shuttle” mechanism [4]. Practical carbonaceous fuels not only contain carbon, but also small amounts of hydrogen, which when released, will lead to an analogous “H2 shuttle” mechanism. Hydrogen gets oxidized at the anode surface forming steam that will then diffuse back to the carbon bed and react to form more CO and H2. How hydrogen in the fuel stock affects the fuel cell operation and performance will be discussed. A detailed mechanism for dry and wet gasification of the carbon bed has previously been developed in the lab and is used in the model [5]. The kinetic parameters needed to describe the half-cell reactions are derived experimentally. Electrochemical impedance spectroscopy (EIS) measurements are taken as a function of temperature, gas composition and cell voltage. The EIS data is used to extract polarization resistances for each half-cell reaction and then fitted to a detailed electrochemical reaction mechanism. Mass transport is important in determining the local gas composition, which affect carbon bed and electrode kinetics, as well as to determine fuel utilization. Any CO or H2 in the exhaust is fuel that is not fully oxidized, and is still capable of undergoing the oxidation reaction to produce electricity in the cell. Thus, fuel utilization improves with an increase in the ratio of (CO2 + H2O)/(CO+H2) in the exit gas, and this influences the overall efficiency of the cell. Since both the Boudouard gasification and the half-cell reactions are temperature dependent, it is important to understand the coupled relationship between reaction rates, heat release, and local temperature. Thus, consideration of heat transfer effects is necessary to develop a better understanding of the cell operation. The model is used to map out the operating space for hydrogen production, power output and cell efficiency. Furthermore, geometrical parameters are tuned to minimize the mole fraction of CO and H2in the exhaust and maximize the overall efficiency. Optimal operating conditions are identified for maintaining high efficiencies while also achieving realistic hydrogen production rates.

Mechanisms of Formation of Natural Hydrogen Reservoirs in Thermal Aquifers - Impact of Bacteria and Gas Bubble Dynamics

Underground hydrogen reservoirs, whose existence has been confirmed recently by geologists all over the world, represent a new source of renewable energy. Hydrogen is formed as the product of reaction of serpentinization between ferromagnesian minerals of the Mantle and water in the offshore zones of subduction or in continental zones at considerable depth beneath hydrothermal aquifers. Initially dissolved in water, hydrogen can create free gas bubbles when the local concentration of H2 dissolved in water exceeds the equilibrium value. The bubbles raise up and create the gas cap of free hydrogen. This process is significantly influenced by methanogen bacteria inhibiting in aquifers and consuming hydrogen for their metabolism. The reactions initiated by bacteria leads to the appearance of other volatile components as methane. The dimension, the form of the gas cap and the concentration of hydrogen and methane determine the efficiency of gas production and the energy potential of the reservoir. In the present paper we develop the conceptual mathematical model of gas cap formation in hydrogen reservoir. The bacterial activity is described by the equation of population dynamics with specific kinetic functions obtained by the authors by treating experimental data. The formation of free gas is modelled in terms of the formation of oversaturated nuclei, their growth and simultaneous motion of isolated bubbles. As far as the bubbles grow, they stick together and create continuous free gas. Thus, the hydrogen motion consists of two stages: (i) the motion of isolated bubbles, controlled by the equations of ganglion dynamics; and (ii) the motion of continuous gas through water, governed by Darcy’s law. The bubble growth is ensured by the mass exchange with hydrogen dissolved in water, which involves a non-equilibrium in the average hydrogen concentrations. Such a problem of hydrogen raising is solved analytically in simplified situation without bacteria. The problem can be reduced to a system of nonlinear hyperbolic equations, which has either continuous or discontinuous solutions (shock waves) depending on the degree of the non-equilibrium. Multiples deformations of the shocks under gas raising are described. The impact of bacteria is studied numerically by using the open source Basilisk (developed by D’Alembert Institute). We have revealed non trivial scenarios of the appearance of piece-wise constant traveling waves, or auto-oscillations caused by the nonlinear population dynamics. The result obtained enables us to give estimation to the characteristic time of gas cap formation and the evolution of its composition in time.

Theoretical study of the mechanism of ruthenium catalyzed dehydrogenation of methanol-water mixture to H2 and CO2

The mechanism for the dehydrogenation of methanol-water mixture catalyzed by [K (dme)2][RuH(trop2dad)] was studied by using the density functional theory method. We found that the imidazole ring acts as a “hydrogen reservoir” by taking the hydrogen atoms from methanol and water and releasing CO2 and three hydrogen molecules. A direct hydride transfer route for the dehydrogenation of formic acid was revealed. Furthermore, we also investigated the solvent effect in the reaction and found that the solvent have significant influence on the structures and relative energies.

Advanced functionalized Mg2AlNiXHZOY nano-oxyhydrides ex-hydrotalcites for hydrogen production from oxidative steam reforming of ethanol

For a sustainable society, it is highly desirable to produce H2 from renewable sources and with low energy consumption. Functional, cheap and easy-prepared Mg2AlNiXHZOY nano-oxyhydrides materials were successfully developed from Mg2AlNiXOY nano-composites ex-hydrotalcites. After an in situ treatment in H2 at low temperature (450 °C), the Mg2AlNiXOY nano-composites (x > 1) become hydrogen reservoirs, called oxyhydrides, with the presence of hydrogen species of hydride nature that can be stored in the anionic vacancies of the solid. Advanced techniques in presence of H2 including TPR, in situ XRD and INS were used to study the nano-composites with different Ni contents. The Mg2AlNiXHZOY nano-oxyhydrides (x > 1) are shown to be able to simultaneously provide hydride species and to totally convert ethanol and produce H2 from a water-ethanol mixture in presence of O2, with very low energy input. In complement to the exothermic partial oxidation reaction, the chemical energy delivered from the strong exothermic reaction between hydride species and O2 is used. The reaction is sustainable because hydride species are replaced and provided by ethanol.

First principle predictions of new crystal structures for hydrogen reservoirs

The demand for clean energies grows rapidly, therefore, research into new materials to be used as hydrogen reservoirs are necessary. With this work we try to provide some understanding on complex hydrides. The compounds studied are of the type Li–X–H, where X are lighter elements in the periodic table. With the participation of these elements we can obtain a high gravimetric hydrogen density. We performed a systematic study on these materials. In this work we used different ab-initio codes. The predictive power of first principle calculations have shown their importance in determining properties of new materials not yet synthesized. The ab-initio calculations help to shorten development times of new materials such as those proposed in this paper. Additionally, new data on materials studied in the past and others designed in this work are shown here.

The deuterium/hydrogen distribution in chondritic organic matter attests to early ionizing irradiation.

Primitive carbonaceous chondrites contain a large array of organic compounds dominated by insoluble organic matter (IOM). A striking feature of this IOM is the systematic enrichment in deuterium compared with the solar hydrogen reservoir. This enrichment has been taken as a sign of low-temperature ion-molecule or gas-grain reactions. However, the extent to which Solar System processes, especially ionizing radiation, can affect D/H ratios is largely unknown. Here, we report the effects of electron irradiation on the hydrogen isotopic composition of organic precursors containing different functional groups. From an initial terrestrial composition, overall D-enrichments and differential intramolecular fractionations comparable with those measured in the Orgueil meteorite were induced. Therefore, ionizing radiation can quantitatively explain the deuteration of organics in some carbonaceous chondrites. For these meteorites, the precursors of the IOM may have had the same isotopic composition as the main water reservoirs of the inner Solar System.