Journal Description
Hydrogen
Hydrogen
is an international, peer-reviewed, open access journal on all aspects of hydrogen published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus, CAPlus / SciFinder, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.4 days after submission; acceptance to publication is undertaken in 2.6 days (median values for papers published in this journal in the first half of 2024).
- Journal Rank: CiteScore - Q2 (Engineering (miscellaneous))
- Recognition of Reviewers: APC discount vouchers, optional signed peer review, and reviewer names published annually in the journal.
Latest Articles
Local Environment and Migration Paths of the Proton Defect in Yttria-Stabilized Zirconia Studied by Ab Initio Calculations and Muon-Spin Spectroscopy
Hydrogen 2024, 5(3), 374-386; https://doi.org/10.3390/hydrogen5030021 - 24 Jun 2024
Abstract
►
Show Figures
The local binding and migration behavior of the proton defect in cubic yttria-stabilized zirconia (YSZ) is studied by first-principles calculations and muon-spin spectroscopy (μSR) measurements. The calculations are based on density-functional theory (DFT) supplemented with a hybrid-functional approach with the proton
[...] Read more.
The local binding and migration behavior of the proton defect in cubic yttria-stabilized zirconia (YSZ) is studied by first-principles calculations and muon-spin spectroscopy (μSR) measurements. The calculations are based on density-functional theory (DFT) supplemented with a hybrid-functional approach with the proton defect embedded in quasi-random supercells of 10.3 mol% yttria content, where the yttrium–zirconium substitutional defects are charge compensated by oxygen vacancies. Representative migration pathways for the proton comprising both transfer and bond reorientation modes are analysed and linked to the underlying microstructure of the YSZ lattice. The μSR data show the evolution of the diamagnetic fraction corresponding to the muon-isotope analogue with an activation energy of diffusion equal to 0.17 eV. Comparisons between the calculations and the experiment allow an assessment of the character of the short-range migration of the proton particle in cubic YSZ.
Full article
Open AccessArticle
Environmental Impact Assessment of a 1 kW Proton-Exchange Membrane Fuel Cell: A Mid-Point and End-Point Analysis
by
Olubayo Moses Babatunde, Busola Dorcas Akintayo, Michael Uzoamaka Emezirinwune and Oludolapo Akanni Olanrewaju
Hydrogen 2024, 5(2), 352-373; https://doi.org/10.3390/hydrogen5020020 - 14 Jun 2024
Abstract
►▼
Show Figures
Proton-exchange membrane fuel cells (PEMFCs) are highly regarded as a promising technology for renewable energy generation; however, the environmental burden in their life cycle is a subject of concern. This study aimed to assess the environmental impact of producing a 1 kW PEMFC
[...] Read more.
Proton-exchange membrane fuel cells (PEMFCs) are highly regarded as a promising technology for renewable energy generation; however, the environmental burden in their life cycle is a subject of concern. This study aimed to assess the environmental impact of producing a 1 kW PEMFC by a well-detailed cradle-to-gate evaluation, using mid-point and end-point impact assessment methods. The environmental impacts are related to the extraction of raw materials, consumption of energy, and transportation processes. Mid-point analysis shows that raw materials extraction and processing have a significant share in some impacts, including freshwater eutrophication, human carcinogenic toxicity, and terrestrial acidification. On the other hand, the energy consumed in fuel cell production plays a significant role in the impact categories of fossil resource depletion and global warming. The highest impact is attributed to the human health end-point analysis (0.000866 DALY), followed by the damage to ecosystems (1.04 × 10−6 species/yr) and resources (USD2013 6.16844). Normalization results further strengthen the importance of human health impacts and the necessity to solve problems regarding toxicity. The results of this work can provide directions toward enhancing the environmental sustainability of PEMFC technology and present a case for adopting a holistic approach to sustainability by looking across the life cycle of the technology.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00020/article_deploy/html/images/hydrogen-05-00020-g001-550.jpg?1718356468)
Figure 1
Open AccessArticle
Enhancing Hydrogen Recovery from Saline Aquifers: Quantifying Wettability and Hysteresis Influence and Minimizing Losses with a Cushion Gas
by
Rana Al Homoud, Marcos Vitor Barbosa Machado, Hugh Daigle, Kamy Sepehrnoori and Harun Ates
Hydrogen 2024, 5(2), 327-351; https://doi.org/10.3390/hydrogen5020019 - 13 Jun 2024
Abstract
►▼
Show Figures
This study aims to numerically assess the impact of wettability and relative permeability hysteresis on hydrogen losses during underground hydrogen storage (UHS) and explore strategies to minimize them by using an appropriate cushion gas. The research utilizes the Carlson model to calculate the
[...] Read more.
This study aims to numerically assess the impact of wettability and relative permeability hysteresis on hydrogen losses during underground hydrogen storage (UHS) and explore strategies to minimize them by using an appropriate cushion gas. The research utilizes the Carlson model to calculate the saturation of trapped gas and the Killough model to account for water hysteresis. By incorporating the Land coefficient based on laboratory-measured data for a hydrogen/brine system, our findings demonstrate a significant influence of gas hysteresis on the hydrogen recovery factor when H2 is used as a cushion gas. The base model, which neglects the hysteresis effect, indicates a recovery factor of 78% by the fourth cycle, which can be improved. In contrast, the modified model, which considers hysteresis and results in a trapped gas saturation of approximately 17%, shows a hydrogen recovery factor of 45% by the fourth cycle. Additionally, gas hysteresis has a notable impact on water production, with an observed 12.5% increase in volume in the model that incorporates gas hysteresis. Furthermore, optimization of the recovery process was conducted by evaluating different cushion gases such as CO2, N2, and CH4, with the latter proving to be the optimal choice. These findings enhance the accuracy of estimating the H2 recovery factor, which is crucial for assessing the feasibility of storage projects.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00019/article_deploy/html/images/hydrogen-05-00019-g001-550.jpg?1718284974)
Figure 1
Open AccessReview
Artificial Intelligence-Driven Innovations in Hydrogen Safety
by
Ravindra R. Patil, Rajnish Kaur Calay, Mohamad Y. Mustafa and Somil Thakur
Hydrogen 2024, 5(2), 312-326; https://doi.org/10.3390/hydrogen5020018 - 8 Jun 2024
Abstract
►▼
Show Figures
This review explores recent advancements in hydrogen gas (H2) safety through the lens of artificial intelligence (AI) techniques. As hydrogen gains prominence as a clean energy source, ensuring its safe handling becomes paramount. The paper critically evaluates the implementation of AI
[...] Read more.
This review explores recent advancements in hydrogen gas (H2) safety through the lens of artificial intelligence (AI) techniques. As hydrogen gains prominence as a clean energy source, ensuring its safe handling becomes paramount. The paper critically evaluates the implementation of AI methodologies, including artificial neural networks (ANN), machine learning algorithms, computer vision (CV), and data fusion techniques, in enhancing hydrogen safety measures. By examining the integration of wireless sensor networks and AI for real-time monitoring and leveraging CV for interpreting visual indicators related to hydrogen leakage issues, this review highlights the transformative potential of AI in revolutionizing safety frameworks. Moreover, it addresses key challenges such as the scarcity of standardized datasets, the optimization of AI models for diverse environmental conditions, etc., while also identifying opportunities for further research and development. This review foresees faster response times, reduced false alarms, and overall improved safety for hydrogen-related applications. This paper serves as a valuable resource for researchers, engineers, and practitioners seeking to leverage state-of-the-art AI technologies for enhanced hydrogen safety systems.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00018/article_deploy/html/images/hydrogen-05-00018-g001-550.jpg?1717846605)
Figure 1
Open AccessArticle
Hydrogen Gas Compression for Efficient Storage: Balancing Energy and Increasing Density
by
Alessandro Franco and Caterina Giovannini
Hydrogen 2024, 5(2), 293-311; https://doi.org/10.3390/hydrogen5020017 - 25 May 2024
Abstract
This article analyzes the processes of compressing hydrogen in the gaseous state, an aspect considered important due to its contribution to the greater diffusion of hydrogen in both the civil and industrial sectors. This article begins by providing a concise overview and comparison
[...] Read more.
This article analyzes the processes of compressing hydrogen in the gaseous state, an aspect considered important due to its contribution to the greater diffusion of hydrogen in both the civil and industrial sectors. This article begins by providing a concise overview and comparison of diverse hydrogen-storage methodologies, laying the groundwork with an in-depth analysis of hydrogen’s thermophysical properties. It scrutinizes plausible configurations for hydrogen compression, aiming to strike a delicate balance between energy consumption, derived from the fuel itself, and the requisite number of compression stages. Notably, to render hydrogen storage competitive in terms of volume, pressures of at least 350 bar are deemed essential, albeit at an energy cost amounting to approximately 10% of the fuel’s calorific value. Multi-stage compression emerges as a crucial strategy, not solely for energy efficiency, but also to curtail temperature rises, with an upper limit set at 200 °C. This nuanced approach is underlined by the exploration of compression levels commonly cited in the literature, particularly 350 bar and 700 bar. The study advocates for a three-stage compression system as a pragmatic compromise, capable of achieving high-pressure solutions while kee** compression work below 10 MJ/kg, a threshold indicative of sustainable energy utilization.
Full article
(This article belongs to the Special Issue Recent Advances in Hydrogen Technologies: Production, Storage and Utilization)
►▼
Show Figures
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00017/article_deploy/html/images/hydrogen-05-00017-g001-550.jpg?1716701018)
Figure 1
Open AccessArticle
Hydrogen Safety by Design: Exclusion of Flame Blow-Out from a TPRD
by
Mina Kazemi, Sile Brennan and Vladimir Molkov
Hydrogen 2024, 5(2), 280-292; https://doi.org/10.3390/hydrogen5020016 - 15 May 2024
Cited by 1
Abstract
►▼
Show Figures
Onboard hydrogen storage tanks are currently fitted with thermally activated pressure relief devices (TPRDs), enabling hydrogen to blowdown in the event of fire. For release diameters below the critical diameter, the flame from the TPRD may blow-out during a pressure drop. Flame blow-outs
[...] Read more.
Onboard hydrogen storage tanks are currently fitted with thermally activated pressure relief devices (TPRDs), enabling hydrogen to blowdown in the event of fire. For release diameters below the critical diameter, the flame from the TPRD may blow-out during a pressure drop. Flame blow-outs pose a safety concern for an indoor or covered environment, e.g., a garage or carpark, where hydrogen can accumulate and deflagrate. This study describes the application of a validated computational fluid dynamics (CFD) model to simulate the dynamic flame behaviour from a TPRD designed to exclude its blow-out. The dynamic behaviour replicates a real scenario. Flame behaviour during tank blowdown through two TPRDs with different nozzle geometries is presented. Simulations confirm flame blow-out for a single-diameter TPRD of 0.5 mm during tank blowdown, while the double-diameter nozzle successfully excludes flame blow-out. The pressure at which the flame blow-out process is initiated during blowdown through a single-diameter nozzle was predicted.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00016/article_deploy/html/images/hydrogen-05-00016-g001-550.jpg?1715779454)
Figure 1
Open AccessReview
Unstable Metal Hydrides for Possible On-Board Hydrogen Storage
by
Zhijie Cao, Franziska Habermann, Konrad Burkmann, Michael Felderhoff and Florian Mertens
Hydrogen 2024, 5(2), 241-279; https://doi.org/10.3390/hydrogen5020015 - 10 May 2024
Abstract
►▼
Show Figures
Hydrogen storage in general is an indispensable prerequisite for the introduction of a hydrogen energy-based infrastructure. In this respect, high-pressure metal hydride (MH) tank systems appear to be one of the most promising hydrogen storage techniques for automotive applications using proton exchange membrane
[...] Read more.
Hydrogen storage in general is an indispensable prerequisite for the introduction of a hydrogen energy-based infrastructure. In this respect, high-pressure metal hydride (MH) tank systems appear to be one of the most promising hydrogen storage techniques for automotive applications using proton exchange membrane (PEM) fuel cells. These systems bear the potential of achieving a beneficial compromise concerning the comparably large volumetric storage density, wide working temperature range, comparably low liberation of heat, and increased safety. The debatable term “unstable metal hydride” is used in the literature in reference to metal hydrides with high dissociation pressure at a comparably low temperature. Such compounds may help to improve the merits of high-pressure MH tank systems. Consequently, in the last few years, some materials for possible on-board applications in such tank systems have been developed. This review summarizes the state-of-the-art developments of these metal hydrides, mainly including intermetallic compounds and complex hydrides, and offers some guidelines for future developments. Since typical laboratory hydrogen uptake measurements are limited to 200 bar, a possible threshold for defining unstable hydrides could be a value of their equilibrium pressure of peq > 200 bar for T < 100 °C. However, these values would mark a technological future target and most current materials, and those reported in this review, do not fulfill these requirements and need to be seen as current stages of development toward the intended target. For each of the aforementioned categories in this review, special care is taken to not only cover the pioneering and classic research but also to portray the current status and latest advances. For intermetallic compounds, key aspects focus on the influence of partial substitution on the absorption/desorption plateau pressure, hydrogen storage capacity and hysteresis properties. For complex hydrides, the preparation procedures, thermodynamics and theoretical calculation are presented. In addition, challenges, perspectives, and development tendencies in this field are also discussed.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00015/article_deploy/html/images/hydrogen-05-00015-g001-550.jpg?1715680851)
Figure 1
Open AccessArticle
Hydrogen Formation from Water with Various Reducing Metals Catalyzed by In Situ-Generated Nickel Nanoparticles
by
Ron Shirman and Yoel Sasson
Hydrogen 2024, 5(2), 230-240; https://doi.org/10.3390/hydrogen5020014 - 3 May 2024
Abstract
►▼
Show Figures
Water is a potential green source for the generation of clean elemental hydrogen without contaminants. One of the most convenient methods for hydrogen generation is based on the oxidation of different metals by water. The inspection of the catalytic activity toward hydrogen formation
[...] Read more.
Water is a potential green source for the generation of clean elemental hydrogen without contaminants. One of the most convenient methods for hydrogen generation is based on the oxidation of different metals by water. The inspection of the catalytic activity toward hydrogen formation from water performed in this study was carried out using four different metals, namely, zinc, magnesium, iron, and manganese. The process is catalyzed by in situ-generated nickel nanoparticles. The zinc–water system was found to be the most effective and exhibited 94% conversion in 4 h. The solid phase in the latter system was characterized by PXRD and SEM techniques. Several blank tests provided a fundamental understanding of the role of each constituent within the system, and a molecular mechanism for the catalytic cycle was proposed.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00014/article_deploy/html/images/hydrogen-05-00014-ag-550.jpg?1714731614)
Graphical abstract
Open AccessArticle
The Case of Renewable Methane by and with Green Hydrogen as the Storage and Transport Medium for Intermittent Wind and Solar PV Energy
by
John G. Ingersoll
Hydrogen 2024, 5(2), 209-229; https://doi.org/10.3390/hydrogen5020013 - 2 May 2024
Abstract
►▼
Show Figures
Long-duration energy storage is the key challenge facing renewable energy transition in the future of well over 50% and up to 75% of primary energy supply with intermittent solar and wind electricity, while up to 25% would come from biomass, which requires traditional
[...] Read more.
Long-duration energy storage is the key challenge facing renewable energy transition in the future of well over 50% and up to 75% of primary energy supply with intermittent solar and wind electricity, while up to 25% would come from biomass, which requires traditional type storage. To this end, chemical energy storage at grid scale in the form of fuel appears to be the ideal option for wind and solar power. Renewable hydrogen is a much-considered fuel along with ammonia. However, these fuels are not only difficult to transport over long distances, but they would also require totally new and prohibitively expensive infrastructure. On the other hand, the existing natural gas pipeline infrastructure in developed economies can not only transmit a mixture of methane with up to 20% hydrogen without modification, but it also has more than adequate long-duration storage capacity. This is confirmed by analyzing the energy economies of the USA and Germany, both possessing well-developed natural gas transmission and storage systems. It is envisioned that renewable methane will be produced via well-established biological and/or chemical processes reacting green hydrogen with carbon dioxide, the latter to be separated ideally from biogas generated via the biological conversion of biomass to biomethane. At the point of utilization of the methane to generate power and a variety of chemicals, the released carbon dioxide would be also sequestered. An essentially net zero carbon energy system would be then become operational. The current conversion efficiency of power to hydrogen/methane to power on the order of 40% would limit the penetration of wind and solar power. Conversion efficiencies of over 75% can be attained with the on-going commercialization of solid oxide electrolysis and fuel cells for up to 75% penetration of intermittent renewable power. The proposed hydrogen/methane system would then be widely adopted because it is practical, affordable, and sustainable.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00013/article_deploy/html/images/hydrogen-05-00013-g001-550.jpg?1714644074)
Figure 1
Open AccessArticle
HyPLANT100: Industrialization from Assembly to the Construction Site for Gigawatt Electrolysis
by
Lukas Büsch, Malte Jakschik, Daniel Syniawa, Christian Masuhr, Lukas Christ, Jan Schachtsiek, Kay Haalck, Leon Nerlich, Elisabeth Frömsdorf, Nadine Schirmack, Benedikt Ebert, Chaman Kirty, Patrick Adler, Thorsten Schüppstuhl and Bernd Kuhlenkötter
Hydrogen 2024, 5(2), 185-208; https://doi.org/10.3390/hydrogen5020012 - 28 Apr 2024
Abstract
►▼
Show Figures
The global push for sustainable energy has heightened the demand for green hydrogen, which is crucial for decarbonizing heavy industry. However, current electrolysis plant capacities are insufficient. This research addresses the challenge through optimizing large-scale electrolysis construction via standardization, modularization, process optimization, and
[...] Read more.
The global push for sustainable energy has heightened the demand for green hydrogen, which is crucial for decarbonizing heavy industry. However, current electrolysis plant capacities are insufficient. This research addresses the challenge through optimizing large-scale electrolysis construction via standardization, modularization, process optimization, and automation. This paper introduces H2Giga, a project for mass-producing electrolyzers, and HyPLANT100, investigating large-scale electrolysis plant structure and construction processes. Modularizing electrolyzers enhances production efficiency and scalability. The integration of AutomationML facilitates seamless information exchange. A digital twin concept enables simulations, optimizations, and error identification before assembly. While construction site automation provides advantages, tasks like connection technologies and handling cables, tubes, and hoses require pre-assembly. This study identifies key tasks suitable for automation and estimating required components. The Enapter Multicore electrolyzer serves as a case study, showcasing robotic technology for tube fittings. In conclusion, this research underscores the significance of standardization, modularization, and automation in boosting the electrolysis production capacity for green hydrogen, contributing to ongoing efforts in decarbonizing the industrial sector and advancing the global energy transition.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00012/article_deploy/html/images/hydrogen-05-00012-g001-550.jpg?1716167886)
Figure 1
Open AccessReview
A Review of Alternative Processes for Green Hydrogen Production Focused on Generating Hydrogen from Biomass
by
Aikaterina Paraskevi Damiri, Emmanuel Stamatakis, Spyros Bellas, Manos Zoulias, Georgios Mitkidis, Anestis G. Anastasiadis, Sotiris Karellas, George Tzamalis, Athanasios Stubos and Theocharis Tsoutsos
Hydrogen 2024, 5(2), 163-184; https://doi.org/10.3390/hydrogen5020011 - 28 Apr 2024
Abstract
►▼
Show Figures
Hydrogen plays a leading role in achieving a future with net zero greenhouse gas emissions. The present challenge is producing green hydrogen to cover the fuel demands of transportation and industry to gain independence from fossil fuels. This review’s goal is to critically
[...] Read more.
Hydrogen plays a leading role in achieving a future with net zero greenhouse gas emissions. The present challenge is producing green hydrogen to cover the fuel demands of transportation and industry to gain independence from fossil fuels. This review’s goal is to critically demonstrate the existing methods of biomass treatment and assess their ability to scale up. Biomass is an excellent hydrogen carrier and biomass-derived processes are the main target for hydrogen production as they provide an innovative pathway to green hydrogen production. Comparing the existing processes, thermochemical treatment is found to be far more evolved than biological or electrochemical treatment, especially with regard to scaling prospects.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00011/article_deploy/html/images/hydrogen-05-00011-g001-550.jpg?1714294713)
Figure 1
Open AccessArticle
On the Scalability of a Membrane Unit for Ultrapure Hydrogen Separation
by
Vincenzo Narcisi, Luca Farina and Alessia Santucci
Hydrogen 2024, 5(2), 149-162; https://doi.org/10.3390/hydrogen5020010 - 17 Apr 2024
Abstract
►▼
Show Figures
Hydrogen permeation sparked a renewed interest in the second half of the 20th century due to the favorable features of this element as an energy factor. Furthermore, niche applications such as nuclear fusion gained attention for the highest selectivity ensured by self-supported dense
[...] Read more.
Hydrogen permeation sparked a renewed interest in the second half of the 20th century due to the favorable features of this element as an energy factor. Furthermore, niche applications such as nuclear fusion gained attention for the highest selectivity ensured by self-supported dense metallic membranes, especially those consisting of Pd-based alloys. In this framework, the ENEA Frascati laboratories have decades of experience in the manufacturing, integration, and operation of Pd-Ag permeators. Most of the experimental investigations were performed on single-tube membranes, proving their performance under relevant operational conditions. Nowadays, once the applicability of this technology has been demonstrated, the scalability of the single-tube experience over medium- and large-scale units must be verified. To do this, ENEA Frascati laboratories have designed and constructed a multi-tube permeator, namely the Medium-Scaled Membrane Reactor (MeSMeR), focused on scalability assessment. In this work, the results obtained with the MeSMeR facility have been compared with previous experimental campaigns conducted on single-tube units, and the scalability of the permeation results has been proven. Moreover, post-test simulations have been performed based on single-tube finite element modeling, proving the scalability of the numerical outcomes and the possibility of using this tool for scale-up design procedures.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00010/article_deploy/html/images/hydrogen-05-00010-g001-550.jpg?1713322252)
Figure 1
Open AccessArticle
Effect of Metal Carbides on Hydrogen Embrittlement: A Density Functional Theory Study
by
Omar Faye and Jerzy A. Szpunar
Hydrogen 2024, 5(1), 137-148; https://doi.org/10.3390/hydrogen5010009 - 20 Mar 2024
Abstract
This study uses plane wave density functional theory (DFT) to investigate the effect of certain metal carbides (Niobium carbide, Vanadium carbide, Titanium carbide, and Manganese sulfide) on hydrogen embrittlement in pipeline steels. Our results predict that the interaction of hydrogen molecules with these
[...] Read more.
This study uses plane wave density functional theory (DFT) to investigate the effect of certain metal carbides (Niobium carbide, Vanadium carbide, Titanium carbide, and Manganese sulfide) on hydrogen embrittlement in pipeline steels. Our results predict that the interaction of hydrogen molecules with these metal carbides occurs in the long range with binding energy varying in the energy window [0.043 eV to 0.70 eV].In addition, our study shows the desorption of H2 molecules from these metal carbides in the chemisorptions. Since atomic state hydrogen interacts with NbC, VC, TiC, and MnS to cause embrittlement, we classified the strength of the hydrogen trap** as TiC + H > VC + H > NbC + H> MnS + H. In addition, our study reveals that the carbon site is a more favorable hydrogen-trap** site than the metal one.
Full article
(This article belongs to the Special Issue Feature Papers in Hydrogen (Volume 2))
►▼
Show Figures
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00009/article_deploy/html/images/hydrogen-05-00009-g001-550.jpg?1710929828)
Figure 1
Open AccessArticle
Effect of Cr/Mn Addition in TiVNb on Hydrogen Sorption Properties: Thermodynamics and Phase Transition Study
by
Anis Bouzidi, Erik Elkaim, Vivian Nassif and Claudia Zlotea
Hydrogen 2024, 5(1), 123-136; https://doi.org/10.3390/hydrogen5010008 - 18 Feb 2024
Cited by 1
Abstract
►▼
Show Figures
High-entropy alloys (HEAs) are a promising class of materials that can grant remarkable functional performances for a large range of applications due to their highly tunable composition. Among these applications, recently, bcc HEAs capable of forming fcc hydrides have been proposed as high-capacity
[...] Read more.
High-entropy alloys (HEAs) are a promising class of materials that can grant remarkable functional performances for a large range of applications due to their highly tunable composition. Among these applications, recently, bcc HEAs capable of forming fcc hydrides have been proposed as high-capacity hydrogen storage materials with improved thermodynamics compared to classical metal hydrides. In this context, a single-phase bcc (TiVNb)0.90Cr0.05Mn0.05 HEA was prepared by arc melting to evaluate the effect of combined Cr/Mn addition in the ternary TiVNb. A thermodynamic destabilization of the fcc hydride phase was found in the HEA compared to the initial TiVNb. In situ neutron and synchrotron X-ray diffraction experiments put forward a fcc → bcc phase transition of the metallic subnetwork in the temperature range of 260–350 °C, whereas the H/D subnetwork underwent an order → disorder transition at 180 °C. The absorption/desorption cycling demonstrated very fast absorption kinetics at room temperature in less than 1 min with a remarkable total capacity (2.8 wt.%) without phase segregation. Therefore, the design strategy consisting of small additions of non-hydride-forming elements into refractory HEAs allows for materials with promising properties for solid-state hydrogen storage to be obtained.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00008/article_deploy/html/images/hydrogen-05-00008-g001-550.jpg?1708244439)
Figure 1
Open AccessArticle
An Exploration of Safety Measures in Hydrogen Refueling Stations: Delving into Hydrogen Equipment and Technical Performance
by
Matteo Genovese, David Blekhman and Petronilla Fragiacomo
Hydrogen 2024, 5(1), 102-122; https://doi.org/10.3390/hydrogen5010007 - 17 Feb 2024
Cited by 3
Abstract
►▼
Show Figures
The present paper offers a thorough examination of the safety measures enforced at hydrogen filling stations, emphasizing their crucial significance in the wider endeavor to advocate for hydrogen as a sustainable and reliable substitute for conventional fuels. The analysis reveals a wide range
[...] Read more.
The present paper offers a thorough examination of the safety measures enforced at hydrogen filling stations, emphasizing their crucial significance in the wider endeavor to advocate for hydrogen as a sustainable and reliable substitute for conventional fuels. The analysis reveals a wide range of crucial safety aspects in hydrogen refueling stations, including regulated hydrogen dispensing, leak detection, accurate hydrogen flow measurement, emergency shutdown systems, fire-suppression mechanisms, hydrogen distribution and pressure management, and appropriate hydrogen storage and cooling for secure refueling operations. The paper therefore explores several aspects, including the sophisticated architecture of hydrogen dispensers, reliable leak-detection systems, emergency shut-off mechanisms, and the implementation of fire-suppression tactics. Furthermore, it emphasizes that the safety and effectiveness of hydrogen filling stations are closely connected to the accuracy in the creation and upkeep of hydrogen dispensers. It highlights the need for materials and systems that can endure severe circumstances of elevated pressure and temperature while maintaining safety. The use of sophisticated leak-detection technology is crucial for rapidly detecting and reducing possible threats, therefore improving the overall safety of these facilities. Moreover, the research elucidates the complexities of emergency shut-off systems and fire-suppression tactics. These components are crucial not just for promptly managing hazards, but also for maintaining the station’s structural soundness in unanticipated circumstances. In addition, the study provides observations about recent technical progress in the industry. These advances effectively tackle current safety obstacles and provide the foundation for future breakthroughs in hydrogen fueling infrastructure. The integration of cutting-edge technology and materials, together with the development of upgraded safety measures, suggests a positive trajectory towards improved efficiency, dependability, and safety in hydrogen refueling stations.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00007/article_deploy/html/images/hydrogen-05-00007-ag-550.jpg?1708672914)
Graphical abstract
Open AccessReview
Hydrogen from Waste Gasification
by
Reinhard Rauch, Yohannes Kiros, Klas Engvall, Efthymios Kantarelis, Paulo Brito, Catarina Nobre, Santa Margarida Santos and Philipp A. Graefe
Hydrogen 2024, 5(1), 70-101; https://doi.org/10.3390/hydrogen5010006 - 10 Feb 2024
Cited by 3
Abstract
►▼
Show Figures
Hydrogen is a versatile energy vector for a plethora of applications; nevertheless, its production from waste/residues is often overlooked. Gasification and subsequent conversion of the raw synthesis gas to hydrogen are an attractive alternative to produce renewable hydrogen. In this paper, recent developments
[...] Read more.
Hydrogen is a versatile energy vector for a plethora of applications; nevertheless, its production from waste/residues is often overlooked. Gasification and subsequent conversion of the raw synthesis gas to hydrogen are an attractive alternative to produce renewable hydrogen. In this paper, recent developments in R&D on waste gasification (municipal solid waste, tires, plastic waste) are summarised, and an overview about suitable gasification processes is given. A literature survey indicated that a broad span of hydrogen relates to productivity depending on the feedstock, ranging from 15 to 300 g H2/kg of feedstock. Suitable gas treatment (upgrading and separation) is also covered, presenting both direct and indirect (chemical loo**) concepts. Hydrogen production via gasification offers a high productivity potential. However, regulations, like frame conditions or subsidies, are necessary to bring the technology into the market.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00006/article_deploy/html/images/hydrogen-05-00006-g001-550.jpg?1707568962)
Figure 1
Open AccessCommunication
Techno-Economic Analysis of Cement Decarbonization Techniques: Oxygen Enrichment vs. Hydrogen Fuel
by
Bruno C. Domingues, Diogo M. F. Santos, Margarida Mateus and Duarte Cecílio
Hydrogen 2024, 5(1), 59-69; https://doi.org/10.3390/hydrogen5010005 - 10 Feb 2024
Abstract
►▼
Show Figures
The Paris Agreement aims to limit global warming, and one of the most polluting sectors is heavy industry, where cement production is a significant contributor. This work briefly explores some alternatives, recycling, reducing clinker content, waste heat recovery, and carbon capture, discussing their
[...] Read more.
The Paris Agreement aims to limit global warming, and one of the most polluting sectors is heavy industry, where cement production is a significant contributor. This work briefly explores some alternatives, recycling, reducing clinker content, waste heat recovery, and carbon capture, discussing their advantages and drawbacks. Then, it examines the economic viability and benefits of increasing oxygen concentration in the primary burning air from 21 to 27 vol.%, which could improve clinker production by 7%, and the production of hydrogen through PEM electrolysis to make up 5% of the fuel thermal fraction, considering both in a cement plant producing 3000 tons of clinker per day. This analysis used reference values from Secil, an international company for cement and building materials, to determine the required scale of the oxygen and hydrogen production, respectively, and calculate the CAPEX of each approach. It is concluded that oxygen enrichment can provide substantial fuel savings for a relatively low cost despite a possible significant increase in NOx emissions. However, hydrogen production at this scale is not currently economically viable.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00005/article_deploy/html/images/hydrogen-05-00005-g001-550.jpg?1707568692)
Figure 1
Open AccessReview
The Use of Copper-Based Delafossite to Improve Hydrogen Production Performance: A Review
by
Hasnae Chfii, Amal Bouich and Bernabé Mari Soucase
Hydrogen 2024, 5(1), 39-58; https://doi.org/10.3390/hydrogen5010004 - 30 Jan 2024
Cited by 1
Abstract
This review paper reports on the use of Delafossite as a layer between perovskite-based solar cells to improve hydrogen production efficiency and make the process easier. The investigation delves into the possible breakthroughs in sustainable energy generation by investigating the synergistic interplay between
[...] Read more.
This review paper reports on the use of Delafossite as a layer between perovskite-based solar cells to improve hydrogen production efficiency and make the process easier. The investigation delves into the possible breakthroughs in sustainable energy generation by investigating the synergistic interplay between Delafossite and solar technology. This investigation covers copper-based Delafossite material’s properties, influence on cell performance, and function in the electrolysis process for hydrogen production. Some reports investigate the synthesis and characterizations of delafossite materials and try to improve their performance using photo electrochemistry. This work sheds light on the exciting prospects of Delafossite integration using experimental and analytical methodologies.
Full article
(This article belongs to the Special Issue Feature Papers in Hydrogen (Volume 2))
►▼
Show Figures
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00004/article_deploy/html/images/hydrogen-05-00004-g001-550.jpg?1706593736)
Figure 1
Open AccessArticle
Hydrogenation Thermodynamics of Ti16V60Cr24−xFex Alloys (x = 0, 4, 8, 12, 16, 20, 24)
by
Francia Ravalison and Jacques Huot
Hydrogen 2024, 5(1), 29-38; https://doi.org/10.3390/hydrogen5010003 - 26 Jan 2024
Abstract
The effect of the partial substitution of Cr with Fe on the thermodynamic parameters of vanadium-rich Ti16V60Cr24-xFex alloys (x = 0, 4, 8, 12, 16, 20, 24) was investigated. For each composition, a pressure–concentration isotherm (PCI)
[...] Read more.
The effect of the partial substitution of Cr with Fe on the thermodynamic parameters of vanadium-rich Ti16V60Cr24-xFex alloys (x = 0, 4, 8, 12, 16, 20, 24) was investigated. For each composition, a pressure–concentration isotherm (PCI) was registered at 298, 308, and 323 K. The PCI curves revealed a reduction in plateau pressure and a decrease in desorbed hydrogen capacity with an increasing amount of Fe. For all alloys, about 50% or less of the initial hydrogen capacity was desorbed for all chosen temperatures. Entropy (ΔS) and enthalpy (ΔH) values were deducted from corresponding Van’t Hoff plots of the PCI curves: the entropy values ranged from −150 to −57 J/K·mol H2, while the enthalpy values ranged from −44 to −21 kJ/mol H2. They both decreased with an increasing amount of Fe. Plotting ΔS as function of ΔH showed a linear variation that seems to indicate an enthalpy–entropy compensation. Moreover, a quality factor analysis demonstrated that the present relationship between entropy and enthalpy is not of a statistical origin at the 99% confidence level.
Full article
(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)
►▼
Show Figures
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00003/article_deploy/html/images/hydrogen-05-00003-g001-550.jpg?1706261571)
Figure 1
Open AccessArticle
Computational Modeling of High-Speed Flow of Two-Phase Hydrogen through a Tube with Abrupt Expansion
by
Konstantin I. Matveev
Hydrogen 2024, 5(1), 14-28; https://doi.org/10.3390/hydrogen5010002 - 18 Jan 2024
Abstract
►▼
Show Figures
Hydrogen can become a prevalent renewable fuel in the future green economy, but technical and economic hurdles associated with handling hydrogen must be overcome. To store and transport hydrogen in an energy-dense liquid form, very cold temperatures, around 20 K, are required. Evaporation
[...] Read more.
Hydrogen can become a prevalent renewable fuel in the future green economy, but technical and economic hurdles associated with handling hydrogen must be overcome. To store and transport hydrogen in an energy-dense liquid form, very cold temperatures, around 20 K, are required. Evaporation affects the achievable mass flow rate during the high-speed transfer of hydrogen at large pressure differentials, and accurate prediction of this process is important for the practical design of hydrogen transfer systems. Computational fluid dynamics modeling of two-phase hydrogen flow is carried out in the present study using the volume-of-fluid method and the Lee relaxation model for the phase change. Suitable values of the relaxation time parameter are determined by comparing numerical results with test data for high-speed two-phase hydrogen flows in a configuration involving a tube with sudden expansion, which is common in practical systems. Simulations using a variable outlet pressure are conducted to demonstrate the dependence of flow rates on the driving pressure differential, including the attainment of the critical flow regime. Also shown are computational results for flows with various inlet conditions and a fixed outlet state. Field distributions of the pressure, velocity, and vapor fractions are presented for several flow regimes.
Full article
![](https://pub.mdpi-res.com/hydrogen/hydrogen-05-00002/article_deploy/html/images/hydrogen-05-00002-g001-550.jpg?1705656388)
Figure 1
Highly Accessed Articles
Latest Books
E-Mail Alert
News
Topics
Topic in
Energies, Materials, Catalysts, Metals, Hydrogen
Hydrogen—The New Energy Vector for the Transition of Industries "Hard to Abate"
Topic Editors: Pasquale Cavaliere, Geoffrey BrooksDeadline: 31 August 2024
Topic in
Catalysts, Hydrogen, Molecules, Nanomaterials, Physchem
Fabrication of Hybrid Materials for Catalysis
Topic Editors: Jerry J. Wu, Michael Arkas, Dimitrios GiannakoudakisDeadline: 30 September 2024
Topic in
Energies, Sustainability, Batteries, Clean Technol., Hydrogen
Hydrogen Technologies vs. Battery Ones in the Green Energy Transition
Topic Editors: Orazio Barbera, Monica Santamaria, Vincenzo BaglioDeadline: 20 November 2024
Topic in
Energies, Catalysts, Hydrogen, Nanoenergy Advances
Hydrogen Energy Technologies, 2nd Volume
Topic Editors: Bahman Shabani, Mahesh SuryawanshiDeadline: 20 January 2025
![loading...](https://pub.mdpi-res.com/img/loading_circle.gif?9a82694213036313?1719563568)
Conferences
Special Issues
Special Issue in
Hydrogen
Promising Electrocatalysts for Hydrogen Production in Acidic Environment
Guest Editor: Mohammed-Ibrahim JameshDeadline: 30 September 2024
Special Issue in
Hydrogen
Recent Advances in Hydrogen Technologies: Production, Storage and Utilization
Guest Editors: Rajender Boddula, Lakshmana Reddy NagappagariDeadline: 31 October 2024
Special Issue in
Hydrogen
Advancements in Hydrogen Storage Materials and DFT-Based Studies
Guest Editors: Emanuel Philipe Pereira Soares Ramos, Mohamed Louzazni, Tariq KamalDeadline: 30 November 2024