Stored Gas Research Articles

Efficiency Enhancement in the Liquefied Natural Gas Storage Scheme: Exploring Thermal Performance for Enhanced Energy Storage Solutions

ABSTRACTThe ongoing transition in the energy sector demands more efficient and reliable energy storage solutions. Our study addresses this need by optimizing the industrial process of liquefied natural gas (LNG) storage, focusing on enhancing thermal performance and energy efficiency. Leveraging a standard LNG storage design, we meticulously evaluated critical supporting variables, modeled key components, and conducted integrated cycle simulations. The primary goal was to minimize the volume of stored gas (achieving a reduction to approximately 1/600th of its gaseous state) while maintaining optimal storage conditions. Our methodology prioritizes insulation over pressure‐bearing factors in large‐scale tanks, aligning with the unique thermal challenges of LNG storage. Simulations were based on methane, which constitutes over 86% of the natural gas in the Middle East, ensuring relevance to the region's resources. The results are promising, with a compression stage reaching a maximum pressure of 2.377, an energy efficiency ratio of 60.71%, and a performance coefficient of 3.188. These findings offer a significant step forward in developing more effective and efficient LNG storage systems, contributing to the broader goal of sustainable energy management.

Design optimization of cubic-shaped pressurant tank for CubeSat propulsion system

From a technical and economic point of view, cold gas propulsion for nanosatellites is one of the more rational systems. There is a problem, however: the optimal spherical shape for a high-pressure vessel only takes up half the cubic volume of the CubeSat unit. To increase the volume, it is proposed to switch to a cubic-shaped tank. The aim of this work is to synthesize the more rational structural design of a pressurant tank that fits within a cubic constraint, which provides the perfect balance between the mass of the structure and the delta-V budget available for the propulsion system. The proposed variants are as follows: a set of four cylinders with spherical bottoms; 14 equal spheres arranged in a face-centered cubic packing; a thin-walled cube supported by ribs, the location and parameters of which provide the smallest mass of the structure; a cube, the reinforcement scheme of which is calculated using topology optimization method; an original polyspheric and bypass design schemes where the filling of the volume of the cube is created by a set of spherical and cylindrical shells of different radii. All the considered vessel variants can be obtained using additive technologies, such as selective laser sintering. For each variant, the internal volume and mass of the vessels were obtained, as well as the delta-V budget, taking into account the mass of the tank and the mass of the stored gas. The analysis of the results reveals that there are two structures that are more rational. The new bypass scheme provides the largest delta-V budget, but it has a 1.6 times larger mass than the initial spherical vessel design. It should be noted that the difference in vessel mass is not crucial for CubeSat form factor satellites. Choosing a rational design may require a larger delta-V budget. The possibility of increasing the reserve delta-V of the CubeSat cold gas propulsion system by 25–35 % due to the transition from a spherical to a cube-shaped tank has been demonstrated. At the same time, the mass of the tank structure increases by 1.6–6.3 times, which can be considered an acceptable price for increasing the efficiency of the propulsion system. The new bypass scheme offers the optimal balance of mass and delta-V reserve.

Polymer Network Comprised of Steroidal Rotors as a Promising Storage Material.

The front cover artwork is provided by Dr habil. Izabella Jastrzebska's group from the University of Białystok, Poland. The image shows a polymeric network with molecular rotors (MR) as crosslinks. The MR rotation is slowed or inhibited when a molecule of stored gas is placed inside the polymer material. Read the full text of the Research Article at 10.1002/cphc.202300793.

Redispatch Model for Real-Time Operation with High Solar-Wind Penetration and Its Adaptation to the Ancillary Services Market

Modern electrical power systems integrate renewable generation, with solar generation being one of the pioneers worldwide. In Latin America, the greatest potential and development of solar generation is found in Chile through the National Electric System. However, its energy matrix faces a crisis of drought and reduction of emissions that limits hydroelectric generation and involves the definitive withdrawal of coal generation. The dispatch of these plants is carried out by the system operator, who uses a simplified mechanism, called “economic merit list” and which does not reflect the real costs of the plants to the damage of the operating and marginal cost of the system. This inefficient dispatch scheme fails to optimize the availability of stored gas and its use over time. Therefore, a real-time redispatch model is proposed that minimizes the operation cost function of the power plants, integrating the variable generation cost as a polynomial function of the net specific fuel consumption, adding gas volume stock restrictions and water reservoirs. In addition, the redispatch model uses an innovative “maximum dispatch power” restriction, which depends on the demand associated with the automatic load disconnection scheme due to low frequency. Finally, by testing real simulation cases, the redispatch model manages to optimize the operation and dispatch costs of power plants, allowing the technical barriers of the market to be broken down with the aim of integrating ancillary services in the short term, using the power reserves in primary (PFC), secondary (SCF), and tertiary (TCF) frequency control.

Assessment of the in situ biomethanation potential of a deep aquifer used for natural gas storage

In response to the challenges of sustainable development and the H2 sector, it is foreseeable that H2 will be stored into geological storage, such as deep aquifers. However, CO2 evolves in deep aquifers because it may be naturally present there; it may also be a constituent of the stored gas mix, or could even be voluntarily stored in the context of the fight against global warming. Autochthonous microorganisms can consume them as sources of energy and carbon (methanogens, (homo)-acetogens and sulfate-reducers). This was already demonstrated in a previous experiment (Haddad 2022) and under operating conditions (Lobodice, Czech Republic ; Smigan 1990). Understanding these mechanisms and quantifying them appear necessary to assess the modifications generated by this type of microorganisms on the properties of the gas. The methanogenesis reaction (CO2 gas + 4H2 gas → CH4 gas + 2H2O liquid) induces a lowering of pressure, since 5 gas molecules are transformed into a single gas molecule: CH4 (water being condensed at subsurface conditions). In situ biomethanation technique could represent a potential on several scales larger than conventional catalytic or biological methanation reactors, due to the very large reservoir volumes involved. Biomethanation in geological reservoirs would enable us to reduce our consumption of fossil fuels, so as not to emit more CO2, while meeting the growing energy needs of a region and ensuring its independence from hydrocarbon-producing countries. A deep aquifer already used as UGS was selected for this study. Formation waters from 17 control wells in this aquifer (Fig. 1) were sampled to assess the potential activity of indigenous methanogenic populations, as well as sulfate-reducers. Despite relatively low sulfate concentrations for a deep aquifer (0.025-1.35 mM), sulfate reducers were found at all sites targeting and quantifying the dsrB gene, which is characteristic of this metabolic group (between 1.8∙101 ±2.0x100 and 1.3∙104 ±2.0∙103 dsrB gene copy numbers.mL-1). In contrast, methanogenic archaea based on the mcrA gene quantification were detected at only 10 of the 17 sites (up to 4.3∙102 ±8.3∙101 mcrA gene copy numbers.mL-1). The choice was made to focus the rest of the study on 7 of these 10 sites. The potential for methanogenesis was assessed on cultural tests with formation water alone or supplemented with calcite (CaCO3), a mineral present in the formation. Results indicate that initial times and controls are controlled by the sulfate variable, since the latter was not consumed by sulfate-reducers. Biotic trials in the presence of calcite and H2/CO2 (abiotic controls and final times) are logically characterized by higher concentrations of calcite, bicarbonate and calcium, but this is not the case for trials in the presence of H2 alone. We therefore deduce that methanogenesis took place mainly via gaseous CO2, but that without the latter, calcite was a source of carbon for lithoautotrophs. Cultures incubated with H2 as the sole gas phase have the highest methane concentrations, logically associated with the lowest sulfate concentrations (consumed by sulfate-reducers), the lowest Eh (probably due to the presence of sulfides) and more alkaline pH values up to 10 (which may have led to precipitation of carbonate and calcium ions). All the sites studied showed sulfate consumption and methane production. Analysis of taxonomic diversity (MiSeq; 16S rRNA gene V4-V5) showed the dominance of three genera of sulfate-reducers with Thermodesulfovibrio-Desulfovibrio-Desulfotomaculum and methanogenic populations belonging to the Methanobacterium genus. These initial results show a strong potential of in situ biomethanation for the deep aquifer studied. All these experiments were carried out at near-atmospheric pressure, and the results still need to be confirmed and refined in the laboratory under conditions that simulate real-life conditions as closely as possible (rock, pressure, nature of gases).

Assessment of landfill gas storage and application regarding energy management: A case study in the province of Quebec, Canada

Landfills are extensively applied to dispose of municipal solid wastes in developed and developing countries. Landfill gas generation from biodegradable organic wastes can be collected and converted to energy. When the gas collection system is shutdown, some of this gas can accumulate and be stored inside the landfill. Using the gas storage capacity of the landfill gets a better management of the landfill site because the collected stored gas could transform the landfill into a cheap gas storage system to provide short-term energy and use the energy when needed. This novel study analyzes the stored methane using the gas collection data of a landfill in Quebec province, Canada, for modulating energy production from landfill gas. Twenty episodes of the gas collection system’s shutdown and restart as well as different gas flow durations were studied. The results showed that the collected stored methane is accumulated in an average of 2.5 h. Additionally, the collected stored methane represents 10.5% of landfill gas flow. Although the results are site-specific, the methodology of this paper can be used on other landfill sites with similar size and collection conditions. Designing new landfills could take into consideration some elements to enhance gas storage capacity. For instance, designing landfill daily covers with more granular materials and higher porosities can be the next step to enhance the landfill as a gas storage system during shutdowns.

Fast Mg-based hydrogen storage with flow-through hydrogen as a cooling medium: A numerical study

The formation of magnesium hydrides through the chemical reaction between magnesium and hydrogen gas is considered one of the most effective hydrogen storage methods. During this reaction process, thermal management is crucial to maintain the reaction active because of the large amount of heat generated, but has been challenging due to the poor heat transfer in the powder bed. In this study, a novel reactor of tooth-shaped configuration is designed for Mg-based hydrogen gas storage, where the hydrogen is not only the stored gas but also serves as the cooling medium in direct contact with the Mg powders. The hydrogen gas in the reactor can flow uniformly through the interior of the Mg plate of compacted powders at a relatively high rate. The proposed direct contact cooling reactor with tooth-shaped configuration is studied numerically in comparison with another direct contact cooling reactor with parallel sheet configuration as well as the traditional reactor with a second cooling medium. The required reaction time for storage for the tooth-shaped configuration is 40% and 78% lower compared with that of the parallel sheet configuration and the traditional reactor, respectively. The reaction rate increases with higher flow rate of hydrogen gas, although at the cost of higher pumping power. When the hydrogen storage rate and the storage density of the total system are the main considerations, the tooth-shaped configuration with flow-through hydrogen demonstrates clear advantages over the other two reactors.

Methane anomaly in soil gas above an abandoned oil & gas exploration borehole in NE Czechia

In the 1950s–1960s, 71 coal and gas exploration wells were drilled in the area of interest in the Western Carpathian Flysch Belt (WCFB) in the NE Czech Republic. Some wells were abandoned while others were used for gas production and storage in the Třanovice underground gas storage (UGS). A monitoring campaign was carried out in place of an earlier abandoned exploration well Žu-108 aiming at proving or ruling out a geochemical relationship of the soil gas and the stored gas in the UGS. The measurements were carried out each month from June 2018 to October 2019 and included amount of methane (CH4), total petroleum gases (CH4 to C4H10), carbon dioxide (CO2) and oxygen (O2) in soil gas in a grid of up to 41 probes. The results show a methane gas peak occurrence with 10 m diameter around the well-top with maximum methane content of 57%vol, while the natural background value of methane content outside the plume is < 500 ppm. The position of the methane peak is associated with significant O2 drop down to 0.25%vol and is surrounded by up to 8.34%vol CO2 halo produced most probably by methanotrophic archea-bacteria. The natural background CO2 values are ca. 0.80%vol. CH4 flux to the atmosphere from the topsoil directly above the well-top of Žu-108 well was measured using the accumulation chamber and range from 2126 to 26 197 g d−1 m−2. The flux increased during drops in atmospheric pressure and ground water level in situ. In contrast, low methane flux was registered after strong rainfalls and when the soil was covered by ice and snow which acted as seal. Based on chemical composition and isotopic signature of methane, the gas is of oil-associated type and methane is thermogenic, similar to that of the original (i.e. pre-UGS) Žukov gas field as well as other small accumulations in the WCFB on the territory of the Czech Republic. It statistically differs from imported mixture of Siberian and Norwegian gas stored in the Třanovice UGS. Based on it, the possible natural gas leakage from the UGS to the Žu-108 is in this case ruled out.

Experimental investigation of shale/hydrogen geochemical interactions

Underground Hydrogen Storage (UHS) is an effective technique that provides safe storage and recovery of the stored hydrogen for long-term energy storage. Shale caprocks are regarded as effective seals of the stored gas, however, one of the key challenges is the in-situ geochemical shale/hydrogen reactions that can impact the seal integrity during injection/production of hydrogen. To address this issue, this work investigates the geochemical reactions between hydrogen and shales, and evaluates the possible alterations in shales’ petro-physical properties. Calcite-rich shale samples are collected from EagleFord (EFS) and Wolfcamp (WCS) shale formations and exposed to pure hydrogen for 108 days under 9.65 MPa at 348 K. Analytical methods including X-ray diffraction, X-ray fluorescence and Scanning Electron Microscope analysis are performed. The results indicate calcite precipitation after hydrogen treatment in both samples due to the presence of organic contents. Sulfate and pyrite reduction reactions with hydrogen are not observed as hydrogen did not all react with sulfate minerals. Consequently, minor changes in the surface pore structure and pore spaces are observed after the treatment, confirming the low reactivity of calcite-rich shale rocks with hydrogen. Gas chromatography analysis shows neither considerable hydrogen loss nor the generation of other gases such as CH4 or CO2 occurred during the experiments. The obtained results suggest that the integrity of shale-caprocks are expected to remain strong during the injection and production of hydrogen, which is favorable for UHS. This work can be a suitable experimental framework to assist in evaluating the hydrogen reactivity to different types of shales with various mineralogy, and assessing the suitability of shale rock for UHS.

“Extreme utilization” theory and practice in gas storages with complex geological conditions

Based on more than 20-year operation of gas storages with complex geological conditions and a series of research findings, the pressure-bearing dynamics mechanism of geological body is revealed. With the discovery of gas-water flowing law of multi-cycle relative permeability hysteresis and differential utilization in zones, the extreme utilization theory targeting at the maximum amount of stored gas, maximum injection-production capacity and maximum efficiency in space utilization is proposed to support the three-in-one evaluation method of the maximum pressure-bearing capacity of geological body, maximum well production capacity and maximum peak shaving capacity of storage space. This study realizes the full potential of gas storage (storage capacity) at maximum pressure, maximum formation-wellbore coordinate production, optimum well spacing density match with finite-time unsteady flow, and peaking shaving capacity at minimum pressure, achieving perfect balance between security and capacity. Operation in gas storages, such as Hutubi in Xinjiang, Xiangguosi in Xinan, and Shuang6 in Liaohe, proves that extreme utilization theory has promoted high quality development of gas storages in China.

Statistical Optimization of Carbon Dioxide Capture Performance by Tri-Solvent System of MEA-DEA-PZ from the Stored Gas Reservoir

Aims/Objective: The current study evaluates the effectiveness of a blended tri-solvent system composed of monoethanolamine (MEA), diethanolamine (DEA), and piperazine (PZ) for removing the carbon dioxide (CO2) from the stored gas reservoir. The developed system is intended to be both environmentally benign and productive. Methods: The CO2 absorption was carried out for the total solvent (5, 10, and 15% v/v), during the course of three temperature ranges (20, 25, and 30°C) while maintaining the reservoir pressure of 1.5, 2, and 2.5 bar. The fraction of DEA: MEA has been restricted to 0.2, 0.5, and 0.8, with simultaneous loading of anhydrous PZ ranging from 0 to 2 gm. and agitation speed for step intervals of 300, 600, and 900 rpm. For the purpose of investigating the synergetic effects of the process parameters on the rapid absorption of CO2 (ξ) and the initial CO2 absorption rate (ε0), Box-Behnken Design (BBD) of response surface methodology (RSM) has been exploited. The design of experiments (DoE) assisted artificial neural network (ANN) and metaheuristic approach of hybridising ANN-whale optimization algorithm (WOA) was also developed and utilised to train and test the developed model. Three optimization models based on RSM, DoE-WOA and ANN-WOA were compared. Under the optimized operating conditions pertaining to DoE, DoE-WOA and DoE-ANN-WOA, (ε0 = 3.340, 3.460 3.513 gm./min-250 mL) and (ξ = 17.114, 18.069, 18.145 gm./250 mL) were obtained. Results: The hybridised DoE-ANN-WOA shows promising results in correlation with the experimental outcomes having error % for ε0 &amp; ξ of 0.790 &amp; 1.31. Conclusion: The DoE-ANN-WOA tends to be selected to predict the optimal absorption conditions as compared to other optimization techniques used in current article.

Physicochemical and microbiological effects of geological biomethane storage in deep aquifers: introduction of O2 as a cocontaminant

The massive arrival of biomethane in geological energy storage will lead to a co-injection of O2 used during the gas desulfurization process. O2 induces changes in the microbial community and interactions with the stored gas and formation water.

Geochemical modelling of hydrogen wettability on Quartz: Implications for underground hydrogen storage in sandstone reservoirs

Renewable energy particular hydrogen can be optimum solution to replace fossil fuels to achieve net-zero carbon emission targets and metigate global warming. One challenge of the hydrogen industry is to safely and economically store hydrogen. To meet this requirement, underground geological storage is a potentially suitable solution to store hydrogen in large-scale and long-term manner. Wettabillity is an important formation parameter that can affect flow behaviors of stored gas, cycling efficiency, structural and residual trap capacity. However, current research is still scarce in geochemical reactions associated hydrogen wettability alteraction in subsurface sandstone reservoirs under in-situ conditions. To fill this knowledge gap, in this study, we performed surface complexation modelling to understand the wettability of hydrogen-brine-organic acid-quartz system. The surface potential of pure quartz at various temperatures and pressure was calculated to characterize disjoining pressure isotherm. Besides, surface species concentrations of quartz and organic stearic acid were predicted to quantify the electrostatic attraction between quartz and organic acid molecues thus the hydrogen wettability on quartz surface.The modelling results show that for pure quartz, increasing temperature and pressure has a negligible effect on disjoining pressure and hydrogen wettability on the pure quartz surface, which is different from the results reported by Iglauer et al., but is in line with the results reported by Hashemi et al. When organic stearic acid is added into system, increasing organic molecules concentration and pressure strengthens the electrostatic attraction of quartz-organic acid and leads to less hydrophilicity and more hydrogen-wetting. This result is consistent with previous contact angle measurements that increasing organic acid concentration increases the brine contact angle, thus the hydrogen wettability. Our work provides a framework to characterize hydrogen wettability on mineral surface using geochemical tools to better assess the feasibility of UHS in depleted sandstone reservoirs.

Cushion and working gases mixing during underground gas storage: Role of fractures

Underground gas storage can help realize sustainable energy supply. This process is based on two main elements, namely cushion gas (CG), which serves to retain the reservoir pressure, and the working gas (WG). In a depleted hydrocarbon reservoir, the required base gas constitutes a large portion of total stored gas. Given the high cost of the base gas for a gas storage project, attempts have been made to reduce this cost by replacing some of the base gas by some less expensive alternative. The main challenge arising from such a replacement is that the CG and WG may mix together, with the mixture exhibiting a lower heat value (HV). In this process, reservoir heterogeneity and fractures, in particular, affect the mixing of the two gases significantly. In this research, the effect of fractures and relevant mechanisms in the replacement of the CG and its mixing with the WG in natural gas storage were numerically simulated. The presence of fracture in the reservoir was found to result in three different behaviors in three different time windows. During early days of production, the fractured reservoir produces a gas of a higher HV than that retrieved from the conventional reservoir. Continuing the production process, however, sets the scene for ending up with a higher HV for the gas retrieved from the conventional reservoir rather than the fractured reservoir. The presence of fractures contributes to the sweeping phenomenon in early production stages but rather boosts the gas mixing effect (GME) in the late production stages, while the sequence is reversed when a conventional reservoir is concerned. A comparison between the CO2 and N2 as alternative CGs showed that the N2 tended to disperse in more layers of the reservoir in presence of fractures, resulting in higher degrees of GME across the reservoir.

Synthesis of attapulgite-MnO2 nanocomposite from manganese complex by ultrasound for hydrogen storage

The research included the synthesis of a new complex of manganese with 3,4,5-tri-methoxybenzoic acid in the presence of triethylamine as a base to which gives the complex with formula [Mn (TMB)2].2H2O. This complex was characterized by FTIR, CHN, magnetic susceptibility and thermal analysis. Furthermore, this complex was used as a novel precursor of manganese in preparing the attapulgite-MnO2 nanocomposite by one-pot addition method using ultrasound. The resulting nanocomposite was characterized by X-ray diffraction and TEM and the results prove that this composite was found as nanochannel of the diameter 45 nm decorated with 26–41 nm of MnO2 nanoparticles. The attapulgite-MnO2 nanocomposite was used in the application of hydrogen storage, and the results proved that attapulgite-MnO2 nanocomposite has the ability to store 3.55 wt% of hydrogen under a pressure of 90 bar and a temperature of 77 K. Furthermore, the measurement demonstrated that increasing the pressure increased the stored hydrogen, implying that the stored gas will be liberated by altering the pressure, implying that the storage will be of the physical kind.

Flow Characterization at Heated Air Supersonic Facility SBR-50

The supersonic wind tunnel facility SBR-50 at the University of Notre Dame was built in 2015 for experimental research related to shock wave (SW) interactions with obstacles and boundary layers (BL) as well as supersonic combustion and a plasma-based flow control. Currently, the facility provides the following range of flow parameters with a test section area at the nozzle exit of 76.2 × 76.2 mm: Mach number M=2 and 4, total pressure p0= 1–4 bar, stagnation temperature T0= 300–775 K, and typical duration of the steady-state flow t= 0.5–2 s. One distinct feature of the facility is the Ohmic gas heater installed in a long plenum section. Objective of this study is to characterize flow in the SBR-50 facility, specifically the dynamics of the gas temperature. Two measuring methods were applied for collection of a detailed dataset: thermocouple measurements and schlieren-based thermal mark (laser spark) velocimetry. The experimental data are compared with 3D Navier–Stokes modelling of the gas parameters over the entire flowpath. Particularly, this study proves that the original facility schematics (the concept of a virtual piston in the plenum) allow for a longer operation with a constant stagnation temperature compared to a constant plenum volume with adiabatic cooling of the stored gas.

Computational Identification and Experimental Demonstration of High‐Performance Methane Sorbents

AbstractRemarkable methane uptake is demonstrated experimentally in three metal‐organic frameworks (MOFs) identified by computational screening: UTSA‐76, UMCM‐152 and DUT‐23‐Cu. These MOFs outperform the benchmark sorbent, HKUST‐1, both volumetrically and gravimetrically, under a pressure swing of 80 to 5 bar at 298 K. Although high uptake at elevated pressure is critical for achieving this performance, a low density of high‐affinity sites (coordinatively unsaturated metal centers) also contributes to a more complete release of stored gas at low pressure. The identification of these MOFs facilitates the efficient storage of natural gas via adsorption and provides further evidence of the utility of computational screening in identifying overlooked sorbents.

Computational Identification and Experimental Demonstration of High-Performance Methane Sorbents.

Remarkable methane uptake is demonstrated experimentally in three metal‐organic frameworks (MOFs) identified by computational screening: UTSA‐76, UMCM‐152 and DUT‐23‐Cu. These MOFs outperform the benchmark sorbent, HKUST‐1, both volumetrically and gravimetrically, under a pressure swing of 80 to 5 bar at 298 K. Although high uptake at elevated pressure is critical for achieving this performance, a low density of high‐affinity sites (coordinatively unsaturated metal centers) also contributes to a more complete release of stored gas at low pressure. The identification of these MOFs facilitates the efficient storage of natural gas via adsorption and provides further evidence of the utility of computational screening in identifying overlooked sorbents.

Solidified Hydrogen Storage (Solid-HyStore) via Clathrate Hydrates

• A comprehensive review on hydrate based hydrogen (H 2 ) storage is presented. • State of the art for various H 2 -containing hydrate systems are evaluated. • Multiple cage occupancy by H 2 and the tuning effect are discussed systematically. • Challenges, limitations, and future directions for the technology are outlined. • Solid-HyStore technology is recommended for stationary storage of hydrogen. With non-renewable fossil fuels depleting rapidly, hydrogen as a clean energy source producing no pollutants or greenhouse gas emissions upon combustion is bound to play a leading role in the future energy landscape. Among the pertinent challenges in establishing a hydrogen-based economy is developing an energy dense hydrogen storage technology with easy recovery of the stored gas. Clathrate hydrates enabling the innovative solidified storage of hydrogen molecules at moderate temperature and pressure conditions carve a niche for safe, long-term, stationary hydrogen storage. This review focuses on the current state of the art for solidified hydrogen storage (Solid-HyStore) via clathrate hydrates. The properties and performances of various H 2 -containing hydrate systems are evaluated and summarized comprehensively. Multiple cage occupancy by H 2 molecules and the tuning effect as the controversial issues in hydrogen hydrate research are elucidated. Finally, the challenges, limitations, and future opportunities for hydrate-based hydrogen storage are identified.

Оценка разрушения газовых баллонов от действия пламени горизонтального факела при расчете пожарного риска

The paper considers potential hazard of block placement of the cylinders with hydrogen and acetylene at the open technological site. The piping of the cylinders of the unit and shut-off and reducing valves are not considered. Analysis of the possibility of cylinders destruction in the block from the action of a horizontal torch during a jet outflow of gas from an emergency cylinder is presented. At the design stage, the prerequisites are considered for excluding from the fire risk calculation the scenario associated with the cascaded destruction of neighboring gas cylinders from the action of a horizontal torch. In the calculation of fire risk, the action of a horizontal torch on the adjacent cylinders leads to their destruction along the entire length of the burning torch. The main parameters of the jet outflow of hydrogen and acetylene from the holes of various diameters in the cylinder body are calculated. Graphical dependences of the maximum value of the thermal radiation of horizontal and vertical torches during the combustion of hydrogen and acetylene at different distances from the source were obtained by a numerical method. Based on the video material of the fire in the warehouse of acetylene cylinders, a qualitative assessment of the duration of the onset of cascaded destruction of cylinders in blocks is presented. Various methods of testing and fire effects on gas cylinders are analyzed to identify the minimum duration before the hull depressurization. The factors that can cause damage to the acetylene cylinder body without destruction are presented. The parameters of the acetylene-oxygen flame used for cutting metals of various thicknesses are evaluated and compared with the flare outflow from the cylinder. The minimum duration of flame exposure to the cylinder body, for through-burning, is substantiated, depending on the design and the stored gas. Additional ways of protecting gas cylinders in the block from possible exposure to the flame of a horizontally flowing gas jet are proposed.