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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A5: Hydrogen Energy".

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 84890

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Dr. Samuel Simon Araya

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Department of Energy Technology, Aalborg University, Fredrik Bajers Vej 5, 9100 Aalborg, Denmark
Interests: PEM fuel cells; PEM water electrolysis; methanol reforming; energy technology; hydrogen
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Dr. Vincenzo Liso

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Guest Editor

Department of Energy Technology, Aalborg University, Fredrik Bajers Vej 5, 9100 Aalborg, Denmark
Interests: energy systems modeling; fuel cells; hydrogen; methanol
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Special Issue Information

Dear Colleagues,

Hydrogen energy research and development has attracted growing attention as one of the key solutions for a clean future energy system. In order to reduce greenhouse gas emissions, national governments across the world are developing ambitious policies to support hydrogen technology, and an increasing level of funding has been allocated for projects of research, development, and demonstration of this technology. At the same time, the private sector is capitalizing on the opportunity with larger investments in hydrogen technology solutions.

While intense research activities have been dedicated to this field, several issues require further research prior to achieving a full commercialization of hydrogen technology solutions. This Special Issue seeks to contribute to disseminating the most recent advancements in the field with respect to both modeling and experimental analysis. The focus is placed on research covering all aspects of the hydrogen energy route, including fuel production, storage, transportation, and final usage. This also includes the development of hydrogen-based fuels, such as ammonia, alcohols, and methane.

We look forward to considering your submissions.

Assoc. Prof. Samuel Simon Araya
Assoc. Prof. Vincenzo Liso
Guest Editors

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Keywords

Fuel cell materials and systems
Electrolysis materials and systems
Catalysis
Hydrogen storage and transportation
Hydrogen based electro-fuels (e.g., methanol, ammonia, enriched methane)
Control and diagnostics

Related Special Issue

Advances in Hydrogen Energy III in Energies (12 articles)

Published Papers (14 papers)

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Research

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17 pages, 6998 KiB

Open AccessArticle

Pore-Scale Modeling of Air–Water Two Phase Flow and Oxygen Transport in Gas Diffusion Layer of Proton Exchange Membrane Fuel Cell

by Chongbo Zhou, Lingyi Guo, Li Chen, Xin Tian, Tiefeng He and Qinghua Yang

Energies 2021, 14(13), 3812; https://0-doi-org.brum.beds.ac.uk/10.3390/en14133812 - 24 Jun 2021

Cited by 8 | Viewed by 1900

Abstract

Understanding multiphase flow and gas transport occurring in electrodes is crucial for improving the performance of proton exchange membrane fuel cells. In the present study, a pore-scale model using the lattice Boltzmann method (LBM) was proposed to study the coupled processes of air–water two-phase flow and oxygen reactive transport processes in porous structures of the gas diffusion layer (GDL) and in fractures of the microscopic porous layer (MPL). Three-dimensional pore-scale numerical results show that the liquid water generation rate is gradually reduced as the oxygen consumption reaction proceeds, and the liquid water saturation in the GDL increases, thus the constant velocity inlet or pressure inlet condition cannot be maintained while the results showed that at t = 1,200,000 iterations after 2900 h running time, the local saturation at the GDL/MPL was about 0.7, and the maximum value was about 0.83, while the total saturation was 0.35. The current density reduced from 2.39 to 0.46 A cm⁻². Effects of fracture number were also investigated, and the results showed that for the fracture numbers of 8, 12, 16, and 24, the breakthrough point number was 4, 3, 3, and 2, respectively. As the fracture number increased, the number of the water breakthrough points at the GDL/GC interface decreased, the liquid water saturation inside the GDL increased, the GDL/MPL interface was more seriously covered, and the current density decreased. The pore-scale model for the coupled multiphase reactive transport processes is helpful for understanding the mechanisms inside the porous electrodes of PEMFC. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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18 pages, 2162 KiB

Open AccessArticle

Effects of Impurities on Pre-Doped and Post-Doped Membranes for High Temperature PEM Fuel Cell Stacks

by Samuel Simon Araya, Sobi Thomas, Andrej Lotrič, Simon Lennart Sahlin, Vincenzo Liso and Søren Juhl Andreasen

Energies 2021, 14(11), 2994; https://0-doi-org.brum.beds.ac.uk/10.3390/en14112994 - 21 May 2021

Cited by 10 | Viewed by 2142

Abstract

In this paper, we experimentally investigated two high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) stacks for their response to the presence of reformate impurities in an anode gas stream. The investigation was aimed at characterizing the effects of reformate impurities at the stack level, including in humidified conditions and identifying fault features for diagnosis purposes. Two HT-PEMFC stacks of 37 cells each with active areas of 165

{cm}^{2}

were used with one stack containing a pre-doped membrane with a woven gas diffusion layer (GDL) and the other containing a post-doped membrane with non-woven GDL. Polarization curves and galvanostatic electrochemical impedance spectroscopy (EIS) were used for characterization. We found that both N₂ dilution and impurities in the anode feed affected mainly the charge transfer losses, especially on the anode side. We also found that humidification alleviated the poisoning effects of the impurities in the stack with pre-doped membrane electrode assemblies (MEA) and woven GDL but had detrimental effects on the stack with post-doped MEAs and non-woven GDL. We demonstrated that pure and dry hydrogen operation at the end of the tests resulted in significant recovery of the performance losses due to impurities for both stacks even after the humidified reformate operation. This implies that there was only limited acid loss during the test period of around 150 h for each stack. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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17 pages, 14700 KiB

Open AccessArticle

Heat Transfer Optimization of NEXA Ballard Low-Temperature PEMFC

by Artem Chesalkin, Petr Kacor and Petr Moldrik

Energies 2021, 14(8), 2182; https://0-doi-org.brum.beds.ac.uk/10.3390/en14082182 - 14 Apr 2021

Cited by 4 | Viewed by 3056

Abstract

Hydrogen is one of the modern energy carriers, but its storage and practical use of the newest hydrogen technologies in real operation conditions still is a task of future investigations. This work describes the experimental hydrogen hybrid energy system (HHS). HHS is part of a laboratory off-grid system that stores electricity gained from photovoltaic panels (PVs). This system includes hydrogen production and storage units and NEXA Ballard low-temperature proton-exchange membrane fuel cell (PEMFC). Fuel cell (FC) loses a significant part of heat during converting chemical energy into electricity. The main purpose of the study was to explore the heat distribution phenomena across the FC NEXA Ballard stack during load with the next heat transfer optimization. The operation of the FC with insufficient cooling can lead to its overheating or even cell destruction. The cause of this undesirable state is studied with the help of infrared thermography and computational fluid dynamics (CFD) modeling with heat transfer simulation across the stack. The distribution of heat in the stack under various loads was studied, and local points of overheating were determined. Based on the obtained data of the cooling air streamlines and velocity profiles, few ways of the heat distribution optimization along the stack were proposed. This optimization was achieved by changing the original shape of the FC cooling duct. The stable condition of the FC stack at constant load was determined. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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12 pages, 5032 KiB

Open AccessArticle

Hydrolysis-Based Hydrogen Generation Investigation of Aluminum System Adding Low-Melting Metals

by Zeng Gao, Fei Ji, Dongfeng Cheng, Congxin Yin, Jitai Niu and Josip Brnic

Energies 2021, 14(5), 1433; https://0-doi-org.brum.beds.ac.uk/10.3390/en14051433 - 05 Mar 2021

Cited by 8 | Viewed by 2161

Abstract

In this age of human civilization, there is a need for more efficient, cleaner, and renewable energy as opposed to that provided by nonrenewable sources such as coal and oil. In this sense, hydrogen energy has been proven to be a better choice. In this paper, a portable graphite crucible metal smelting furnace was used to prepare ten multi-element aluminum alloy ingots with different components. The microstructure and phase composition of the ingots and reaction products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The reaction was carried out in a constant temperature water bath furnace at 60 °C, and the hydrogen production performance of the multi-element aluminum alloys in different proportions was compared by the drainage gas collection method. The experimental results show that the as-cast microstructure of Al–Ga–In–Sn aluminum alloy is composed of a solid solution of Al and part of Ga, and a second phase of In₃Sn. After the hydrolysis reaction, the products were dried at 150 °C and then analyzed by XRD. The products were mainly composed of AlOOH and In₃Sn. Alloys with different compositions react at the same hydrolysis temperature, and the hydrogen production performance is related to the ratio of low-melting-point metal elements. By comparing two different ratios of Ga–In–Sn (GIS), the hydrogen production capacity and production rate when the ratio is 6:3:1 are generally higher than those when the ratio is 7:2:1. The second phase content affects the hydrogen production performance. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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13 pages, 4721 KiB

Open AccessArticle

Numerical Simulations of Cryogenic Hydrogen Cooling in Vortex Tubes with Smooth Transitions

by Konstantin I. Matveev and Jacob Leachman

Energies 2021, 14(5), 1429; https://0-doi-org.brum.beds.ac.uk/10.3390/en14051429 - 05 Mar 2021

Cited by 4 | Viewed by 2402

Abstract

Improving efficiency of hydrogen cooling in cryogenic conditions is important for the wider applications of hydrogen energy systems. The approach investigated in this study is based on a Ranque-Hilsch vortex tube (RHVT) that generates temperature separation in a working fluid. The simplicity of RHVT is also a valuable characteristic for cryogenic systems. In the present work, novel shapes of RHVT are computationally investigated with the goal to raise efficiency of the cooling process. Specifically, a smooth transition is arranged between a vortex chamber, where compressed gas is injected, and the main tube with two exit ports at the tube ends. Flow simulations have been carried out using STAR-CCM+ software with the real-gas Redlich-Kwong model for hydrogen at temperatures near 70 K. It is determined that a vortex tube with a smooth transition of moderate size manifests about 7% improvement of the cooling efficiency when compared vortex tubes that use traditional vortex chambers with stepped transitions and a no-chamber setup with direct gas injection. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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19 pages, 3096 KiB

Open AccessArticle

Operation of a Solid Oxide Fuel Cell Based Power System with Ammonia as a Fuel: Experimental Test and System Design

by Linda Barelli, Gianni Bidini and Giovanni Cinti

Energies 2020, 13(23), 6173; https://0-doi-org.brum.beds.ac.uk/10.3390/en13236173 - 24 Nov 2020

Cited by 27 | Viewed by 3536

Abstract

Ammonia has strong potentialities as sustainable fuel for energy applications. NH₃ is carbon free and can be synthetized from renewable energy sources (RES). In Solid Oxide Fuel Cells, NH₃ reacts electrochemically thereby avoiding the production of typical combustion pollutants such as NOx. In this study, an ammonia-fueled solid oxide fuel cells (SOFC) system design is proposed and a thermodynamic model is developed to evaluate its performance. A SOFC short stack was operated with NH₃ in a wide range of conditions. Experimental results are implemented in the thermodynamic model. Electrical efficiency of 52.1% based on ammonia Lower Heating Value is calculated at a net power density of 0.36 W cm_FC⁻². The operating conditions of the after burner and of the ammonia decomposition reactor are studied by varying the values of specific parameters. The levelized cost of energy of 0.221 $ kWh⁻¹ was evaluated, as introduced by the International Energy Agency, for a system that operates at nominal conditions and at a reference power output of 100 kW. This supports the feasibility of ammonia-fueled SOFC systems with reference to the carbon free energy market, specifically considering the potential development of green ammonia production. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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18 pages, 10379 KiB

Open AccessArticle

Optimization Design of Rib Width and Performance Analysis of Solid Oxide Electrolysis Cell

by Meiting Guo, Xiao Ru, Zijing Lin, Guoping Xiao and Jianqiang Wang

Energies 2020, 13(20), 5468; https://0-doi-org.brum.beds.ac.uk/10.3390/en13205468 - 19 Oct 2020

Cited by 9 | Viewed by 2593

Abstract

Structure design is of great value for the performance improvement of solid oxide electrolysis cells (SOECs) to diminish the gap between scientific research and industrial application. A comprehensive multi-physics coupled model is constructed to conduct parameter sensitivity analysis to reveal the primary and secondary factors on the SOEC performance and optimal rib width. It is found that the parameters of the O₂ electrode have almost no influence on the optimal rib width at the H₂ electrode side and vice versa. The optimized rib width is not sensitive to the electrode porosity, thickness, electrical conductivity and gas composition. The optimal rib width at the H₂ electrode side is sensitive to the contact resistance at the interface between the electrode and interconnect rib, while the extremely small concentration loss at the O₂ electrode leads to the insensitivity of optimal rib width to the parameters influencing the O₂ diffusion. In addition to the contact resistance, the applied cell voltage and pitch width also has a dramatic influence on the optimal rib width of the fuel electrode. An analytical expression considering the influence of total cell polarization loss, the pitch width and the contact resistance is further developed for the benefit of the engineering society. The maximum error in the cell performance between the numerically obtained and analytically acquired optimal rib width is only 0.14% and the predictive power of the analytical formula is fully verified. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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17 pages, 1949 KiB

Open AccessArticle

System Design and Modeling of a High Temperature PEM Fuel Cell Operated with Ammonia as a Fuel

by Giovanni Cinti, Vincenzo Liso, Simon Lennart Sahlin and Samuel Simon Araya

Energies 2020, 13(18), 4689; https://0-doi-org.brum.beds.ac.uk/10.3390/en13184689 - 09 Sep 2020

Cited by 7 | Viewed by 4105

Abstract

Ammonia is a hydrogen-rich compound that can play an important role in the storage of green hydrogen and the deployment of fuel cell technologies. Nowadays used as a fertilizer, NH₃ has the right peculiarities to be a successful sustainable fuel for the future of the energy sector. This study presents, for the first time in literature, an integration study of ammonia as a hydrogen carrier and a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) as an energy conversion device. A system design is presented, that integrates a reactor for the decomposition of ammonia with an HT-PEMFC, where hydrogen produced from NH₃ is electrochemically converted into electricity and heat. The overall system based on the two technologies is designed integrating all balance of plant components. A zero-dimensional model was implemented to evaluate system efficiency and study the effects of parametric variations. Thermal equilibrium of the decomposition reactor was studied, and two different strategies were implemented in the model to guarantee thermal energy balance inside the system. The results show that the designed system can operate with an efficiency of 40.1% based on ammonia lower heating value (LHV) at the fuel cell operating point of 0.35 A/cm² and 0.60 V. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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14 pages, 4205 KiB

Open AccessArticle

A Computational Analysis of a Methanol Steam Reformer Using Phase Change Heat Transfer

by Hyemin Song, Younghyeon Kim, Dongjin Yu, Byoung Jae Kim, Hyunjin Ji and Sangseok Yu

Energies 2020, 13(17), 4324; https://0-doi-org.brum.beds.ac.uk/10.3390/en13174324 - 21 Aug 2020

Cited by 3 | Viewed by 2716

Abstract

A methanol steam reformer converts methanol and steam into a hydrogen-rich mixture through an endothermic reaction. The methanol reformer is divided into a reaction section and a heat supply section that transfers thermal energy from 200 to 300 °C. This study presents the behavior of the methanol steam reforming reaction using the latent heat of the steam. A numerical analysis was separately conducted for two different regimes assuming constant heat flux conditions. A methanol steam reformer is an annulus structure that has a phase change heat transfer from an outer tube to an inner tube. Different from the steam zone temperature in the tube, the latent heat of steam condensation decreases, and there is a gradual between-wall temperature decrease along the longitudinal direction. Since the latent heat of steam condensation is very sensitive to the requested heat from the reformer, it is necessary to consider a refined design of a methanol reformer to obtain a large enough amount of heat by steam condensation. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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14 pages, 1646 KiB

Open AccessArticle

A Thermodynamic Analysis of an Air-Cooled Proton Exchange Membrane Fuel Cell Operated in Different Climate Regions

by Torsten Berning and Søren Knudsen Kær

Energies 2020, 13(10), 2611; https://0-doi-org.brum.beds.ac.uk/10.3390/en13102611 - 20 May 2020

Cited by 13 | Viewed by 3047

Abstract

A fundamental thermodynamic analysis of an air-cooled fuel cell, where the reactant air stream is also the coolant stream, is presented. The adiabatic cell temperature of such a fuel cell is calculated in a similar way as the adiabatic flame temperature in a combustion process. Diagrams that show the dependency of the cathode outlet temperature, the stoichiometric flow ratio and the operating cell voltage are developed. These diagrams can help fuel cell manufacturers to identify a suitable blower and a suitable operating regime for their fuel cell stacks. It is found that for standard conditions, reasonable cell temperatures are obtained for cathode stoichiometric flow ratios of ξ = 50 and higher, which is in very good agreement with manufacturer’s recommendations. Under very cold ambient conditions, the suggested stoichiometric flow ratio is only in the range of ξ = 20 in order to obtain a useful fuel cell operating temperature. The outside relative humidity only plays a role at ambient temperatures above 40 °C, and the predicted stoichiometric flow ratios should be above ξ = 70 in this region. From a thermodynamic perspective, it is suggested that the adiabatic outlet temperature is a suitable definition of the fuel cell operating temperature. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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18 pages, 5209 KiB

Open AccessArticle

Performance Study on Methanol Steam Reforming Rib Micro-Reactor with Waste Heat Recovery

by Guoqiang Wang, Feng Wang and Bohong Chen

Energies 2020, 13(7), 1564; https://0-doi-org.brum.beds.ac.uk/10.3390/en13071564 - 27 Mar 2020

Cited by 16 | Viewed by 2657

Abstract

Automobile exhaust heat recovery is considered to be an effective means to enhance fuel utilization. The catalytic production of hydrogen by methanol steam reforming is an attractive option for onboard mobile applications, due to its many advantages. However, the reformers of conventional packed bed type suffer from axial temperature gradients and cold spots resulting from severe limitations of mass and heat transfer. These disadvantages limit reformers to a low efficiency of catalyst utilization. A novel rib microreactor was designed for the hydrogen production from methanol steam reforming heated by automobile exhaust, and the effect of inlet exhaust and methanol steam on reactor performance was numerically analyzed in detail, with computational fluid dynamics. The results showed that the best operating parameters were the counter flow, water-to-alcohol (W/A) of 1.3, exhaust inlet velocity of 1.1 m/s, and exhaust inlet temperature of 773 K, when the inlet velocity and inlet temperature of the reactant were 0.1 m/s and 493 K, respectively. At this condition, a methanol conversion of 99.4% and thermal efficiency of 28% were achieved, together with a hydrogen content of 69.6%. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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Review

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27 pages, 3608 KiB

Open AccessReview

Towards Non-Mechanical Hybrid Hydrogen Compression for Decentralized Hydrogen Facilities

by Giuseppe Sdanghi, Gaël Maranzana, Alain Celzard and Vanessa Fierro

Energies 2020, 13(12), 3145; https://0-doi-org.brum.beds.ac.uk/10.3390/en13123145 - 17 Jun 2020

Cited by 53 | Viewed by 9482

Abstract

The cost of the hydrogen value chain needs to be reduced to allow the widespread development of hydrogen applications. Mechanical compressors, widely used for compressing hydrogen to date, account for more than 50% of the CAPEX (capital expenditure) in a hydrogen refueling station. Moreover, mechanical compressors have several disadvantages, such as the presence of many moving parts, hydrogen embrittlement, and high consumption of energy. Non-mechanical hydrogen compressors have proven to be a valid alternative to mechanical compressors. Among these, electrochemical compressors allow isothermal, and therefore highly efficient, compression of hydrogen. On the other hand, adsorption-desorption compressors allow hydrogen to be compressed through cooling/heating cycles using highly microporous materials as hydrogen adsorbents. A non-mechanical hybrid hydrogen compressor, consisting of a first electrochemical stage followed by a second stage driven by adsorption-desorption of hydrogen on activated carbons, allows hydrogen to be produced at 70 MPa, a value currently required for the development of hydrogen automotive applications. This system has several advantages over mechanical compressors, such as the absence of moving parts and high compactness. Its use in decentralized hydrogen facilities, such as hydrogen refueling stations, can be considered. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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25 pages, 1883 KiB

Open AccessReview

Ammonia as Effective Hydrogen Storage: A Review on Production, Storage and Utilization

by Muhammad Aziz, Agung Tri Wijayanta and Asep Bayu Dani Nandiyanto

Energies 2020, 13(12), 3062; https://0-doi-org.brum.beds.ac.uk/10.3390/en13123062 - 12 Jun 2020

Cited by 271 | Viewed by 39128

Abstract

Ammonia is considered to be a potential medium for hydrogen storage, facilitating CO₂-free energy systems in the future. Its high volumetric hydrogen density, low storage pressure and stability for long-term storage are among the beneficial characteristics of ammonia for hydrogen storage. Furthermore, ammonia is also considered safe due to its high auto ignition temperature, low condensation pressure and lower gas density than air. Ammonia can be produced from many different types of primary energy sources, including renewables, fossil fuels and surplus energy (especially surplus electricity from the grid). In the utilization site, the energy from ammonia can be harvested directly as fuel or initially decomposed to hydrogen for many options of hydrogen utilization. This review describes several potential technologies, in current conditions and in the future, for ammonia production, storage and utilization. Ammonia production includes the currently adopted Haber–Bosch, electrochemical and thermochemical cycle processes. Furthermore, in this study, the utilization of ammonia is focused mainly on the possible direct utilization of ammonia due to its higher total energy efficiency, covering the internal combustion engine, combustion for gas turbines and the direct ammonia fuel cell. Ammonia decomposition is also described, in order to give a glance at its progress and problems. Finally, challenges and recommendations are also given toward the further development of the utilization of ammonia for hydrogen storage. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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Other

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10 pages, 834 KiB

Open AccessHypothesis

On the Nature of Electro-Osmotic Drag

by Torsten Berning

Energies 2020, 13(18), 4726; https://0-doi-org.brum.beds.ac.uk/10.3390/en13184726 - 10 Sep 2020

Cited by 3 | Viewed by 4387

Abstract

Electro-osmotic drag (EOD) is usually thought of as a transport mechanism of water inside and through the polymer electrolyte membrane (PEM) in electrochemical devices. However, it has already been shown that the transport of dissolved water in the PEM occurs exclusively via diffusion, provided that the EOD coefficient n_d is constant. Consequently, EOD is not a water transport mechanism inside the electrolyte membrane, and this means that its nature is not yet understood. This work proposes a theory that suggests that the root of the EOD is located in the catalyst layers of the electrochemical device where the electric current is generated, and consequently could be linked to one or more of the elementary reaction steps. It is therefore also conceivable that EOD exists at one electrode in an electrochemical device, but not in the other. Moreover, the EOD coefficient n_d may depend on the current density as well as the oxidization level of the catalyst. The last consequence, if EOD is linked to an elementary reactions step, it could also be part of the rate-determining elementary step, and this could open pathways to increase the reaction kinetics by finding ways of enhancing the water/hydronium ion transport out of or into the polymer phase. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy)

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