Hydrogen Energy Technologies

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.0	6.2	2008	17.5 Days	CHF 2600
Sci sci	-	4.5	2019	27.4 Days	CHF 1200
Hydrogen hydrogen	-	3.6	2020	15.4 Days	CHF 1000

8 pages, 3671 KiB

Open AccessArticle

Physical Properties of Ti₄₅Zr₃₈Fe₁₇ Alloy and Its Amorphous Hydride

by Antoni Żywczak, Łukasz Gondek, Joanna Czub, Piotr Janusz, Nivas Babu Selvaraj and Akito Takasaki

Energies 2022, 15(12), 4236; https://doi.org/10.3390/en15124236 - 9 Jun 2022

Cited by 1 | Viewed by 1936

Abstract

The alloys based on Ti-Zr are considered an excellent candidate for hydrogen storage applications. In this communication, we report the results of Fe substitution for Ni in the well-known Ti₄₅Zr₃₈Ni₁₇ compound. The parent and related compounds can be [...] Read more.

The alloys based on Ti-Zr are considered an excellent candidate for hydrogen storage applications. In this communication, we report the results of Fe substitution for Ni in the well-known Ti₄₅Zr₃₈Ni₁₇ compound. The parent and related compounds can be obtained as amorphous powders, transforming into the quasicrystalline phase (i-phase) after annealing. The amorphous Ti₄₅Zr₃₈Fe₁₇ phase is transformed into the icosahedral quasicrystalline state, and it is a quasi-continuous process. The i-phase is well-developed close to 500 °C. At higher temperatures, the quasicrystal structure transforms into the other phase: the w-phase (an approximant to the crystalline phase) and another crystal phase with a small addition of the FeZr₃ and the Fe₂(ZrTi)₃. The amorphous Ti₄₅Zr₃₈Fe₁₇ phases can be hydrogenated while maintaining the amorphous nature, which constitutes another very fascinating research field for our group. The investigated alloy shows a good capacity for gaseous H₂ at level 2.54 wt.% at elevated temperatures. The ferromagnetic signal of the amorphous TiZrFe comes from magnetic nanocrystallites in the amorphous matrix. After heating, the magnetic signal significantly decreases due to the lack of long-range magnetic ordering in the i-phase of the Ti₄₅Zr₃₈Fe₁₇ alloy. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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24 pages, 6512 KiB

Open AccessArticle

A Holistic Consideration of Megawatt Electrolysis as a Key Component of Sector Coupling

by Bernd Emonts, Martin Müller, Michael Hehemann, Holger Janßen, Roger Keller, Markus Stähler, Andrea Stähler, Veit Hagenmeyer, Roland Dittmeyer, Peter Pfeifer, Simon Waczowicz, Michael Rubin, Nina Munzke and Stefan Kasselmann

Energies 2022, 15(10), 3656; https://doi.org/10.3390/en15103656 - 16 May 2022

Cited by 2 | Viewed by 5904

Abstract

In the future, hydrogen (H₂) will play a significant role in the sustainable supply of energy and raw materials to various sectors. Therefore, the electrolysis of water required for industrial-scale H₂ production represents a key component in the generation of [...] Read more.

In the future, hydrogen (H₂) will play a significant role in the sustainable supply of energy and raw materials to various sectors. Therefore, the electrolysis of water required for industrial-scale H₂ production represents a key component in the generation of renewable electricity. Within the scope of fundamental research work on cell components for polymer electrolyte membrane (PEM) electrolyzers and application-oriented living labs, an MW electrolysis system was used to further improve industrial-scale electrolysis technology in terms of its basic structure and systems-related integration. The planning of this work, as well as the analytical and technical approaches taken, along with the essential results of research and development are presented herein. The focus of this study is the test facility for a megawatt PEM electrolysis stack with the presentation of the design, processing, and assembly of the main components of the facility and stack. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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21 pages, 7234 KiB

Open AccessArticle

Thermoelectric Generator as the Waste Heat Recovery Unit of Proton Exchange Membrane Fuel Cell: A Numerical Study

by Hossein Pourrahmani, Hamed Shakeri and Jan Van herle

Energies 2022, 15(9), 3018; https://doi.org/10.3390/en15093018 - 20 Apr 2022

Cited by 21 | Viewed by 3370

Abstract

The proton exchange membrane fuel cell (PEMFC) is a prominent environmentally friendly alternative candidate to internal combustion engines in automotive applications. The recovery of the waste heat of light-duty diesel engines has been investigated recently, which is similarly relevant for PEMFCs. Thermoelectric generators [...] Read more.

The proton exchange membrane fuel cell (PEMFC) is a prominent environmentally friendly alternative candidate to internal combustion engines in automotive applications. The recovery of the waste heat of light-duty diesel engines has been investigated recently, which is similarly relevant for PEMFCs. Thermoelectric generators (TEG) applied on the stack’s walls have been already proposed and tested as a cooling method for small scale applications of the PEMFC. For the medium scale usages of the PEMFC stack, TEG technology may be further used to recover heat lost through the cooling water required for stack thermal management, which was the focus of the present study. Using an agglomerate model for the PEMFC and a computational fluid dynamic (CFD) thermal model for the TEG heat exchanger unit, the operation and performance of the PEMFC stack and heat recovery unit were simulated, respectively. After validation, results indicated that the transferred heat from the PEMFC to the cooling channel increased the temperature of the coolant from room temperature to 330.5 K at the current density of 0.8 A/cm². CFD analysis revealed that 37.7 W of the heated wasted by the PEMFC stack could be recovered by the currently available TEG material and geometry. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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13 pages, 2475 KiB

Open AccessArticle

Influence of Low Inlet Pressure and Temperature on the Compressor Map Limits of Electrical Turbo Chargers for Airborne Fuel Cell Applications

by Jonas Schröter, Daniel Frank, Valentin Radke, Christiane Bauer, Josef Kallo and Caroline Willich

Energies 2022, 15(8), 2896; https://doi.org/10.3390/en15082896 - 15 Apr 2022

Cited by 6 | Viewed by 3122

Abstract

For the optimal high-efficiency operation of a PEM fuel cell system, the temperature, pressure, humidity and mass flow of the supplied air must be tuned to the fuel cell stack requirements. Especially for aircraft applications, this requires a thorough understanding of the fuel [...] Read more.

For the optimal high-efficiency operation of a PEM fuel cell system, the temperature, pressure, humidity and mass flow of the supplied air must be tuned to the fuel cell stack requirements. Especially for aircraft applications, this requires a thorough understanding of the fuel cell air supply system behavior and how it changes when the ambient pressure is below 1 bar(a) during flight. This work investigates the influence of low inlet pressures and varying inlet temperatures on the compression map of an electrical turbo charger. This is especially relevant in airborne fuel cell application and not much literature can be found on that topic. Compressor limits are evaluated experimentally and theoretically. The theory of mass flow and speed correction is compared to experimental findings and found to be applicable for the surge and speed limit of the investigated turbo chargers as long as the compressor map is not limited by the power of the electric motor and inverter. Based on this, a prediction of the compressor map for altitudes up to 10,000 m is made with the help of a developed software tool. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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14 pages, 295 KiB

Open AccessReview

Law and Policy Review on Green Hydrogen Potential in ECOWAS Countries

by Abdoulaye Ballo, Koffi Kouakou Valentin, Bruno Korgo, Kehinde Olufunso Ogunjobi, Solomon Nwabueze Agbo, Daouda Kone and Moumini Savadogo

Energies 2022, 15(7), 2304; https://doi.org/10.3390/en15072304 - 22 Mar 2022

Cited by 22 | Viewed by 5194

Abstract

This paper aims to review existing energy-sector and hydrogen-energy-related legal, policy, and strategy documents in the ECOWAS region. To achieve this aim, current renewable-energy-related laws, acts of parliament, executive orders, presidential decrees, administrative orders, and memoranda were analyzed. The study shows that ECOWAS [...] Read more.

This paper aims to review existing energy-sector and hydrogen-energy-related legal, policy, and strategy documents in the ECOWAS region. To achieve this aim, current renewable-energy-related laws, acts of parliament, executive orders, presidential decrees, administrative orders, and memoranda were analyzed. The study shows that ECOWAS countries have strived to design consistent legal instruments regarding renewable energy in developing comprehensive legislation and bylaws to consolidate it and to encourage investments in renewable energy. Despite all these countries having a legislative basis for regulating renewable energy, there are still weaknesses that revolve around the law and policy regarding its possible application in green hydrogen production and use. The central conclusion of this review paper is that ECOWAS member states presently have no official hydrogen policies nor bylaws in place. The hydrogen rise presents a challenge and opportunity for members to play an important role in the fast-growing global hydrogen market. Therefore, these countries need to reform their regulatory frameworks and align their policies by introducing green hydrogen production in order to accomplish their green economy transition for the future and to boost the continent’s sustainable development. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

12 pages, 4125 KiB

Open AccessFeature PaperArticle

Hydrogen Production by Water Electrolysis with Low Power and High Efficiency Based on Pre-Magnetic Polarization

by Ke Li, Heng Zhang, Xiaoyu Zheng, Chang Liu and Qianding Chen

Energies 2022, 15(5), 1878; https://doi.org/10.3390/en15051878 - 3 Mar 2022

Cited by 12 | Viewed by 3661

Abstract

In this paper, a method of efficient hydrogen production using low-power electrolysis based on pre-magnetic polarization was proposed in order to improve the rate of hydrogen production by water electrolysis, with reduced energy consumption, molecular polarity, and stress–strain characteristics of distilled water under [...] Read more.

In this paper, a method of efficient hydrogen production using low-power electrolysis based on pre-magnetic polarization was proposed in order to improve the rate of hydrogen production by water electrolysis, with reduced energy consumption, molecular polarity, and stress–strain characteristics of distilled water under the condition of a pre-magnetic field. By constructing a microphysical model of hydrogen proton energy-level transition and a macroscopic mathematical model corresponding to magnetization vector-polarization hydrogen proton concentration in the pre-magnetic field, the ionic conductivity, electrolyte current density, interelectrode voltage, and hydrogen production efficiency under a varying magnetic field were qualitatively and quantitatively analyzed. In addition, an adjustable pre-magnetic polarization hydrolyzing hydrogen production test platform was set up to verify the effectiveness of the proposed method. The repeated test results, within a magnetic field strength range of 0–10,000 GS, showed that the conductivity of distilled water after pre-magnetic polarization treatment increased by 2–3 times, the electrolytic current density of the PEM (Proton Exchange Membrane) increased with increasing magnetic field strength, the voltage between the poles continuously decreased, and the hydrogen production rate was significantly improved. When the magnetic field strength reached 10,000 GS, the rate of hydrogen production by the electrolysis of distilled water increased by 15–20% within a certain period of time. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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23 pages, 2882 KiB

Open AccessArticle

An Intelligent Site Selection Model for Hydrogen Refueling Stations Based on Fuzzy Comprehensive Evaluation and Artificial Neural Network—A Case Study of Shanghai

by Yan Zhou, Xunpeng Qin, Chenglong Li and Jun Zhou

Energies 2022, 15(3), 1098; https://doi.org/10.3390/en15031098 - 1 Feb 2022

Cited by 11 | Viewed by 3332

Abstract

With the gradual popularization of hydrogen fuel cell vehicles (HFCVs), the construction and planning of hydrogen refueling stations (HRSs) are increasingly important. Taking operational HRSs in China’s coastal and major cities as examples, we consider the main factors affecting the site selection of [...] Read more.

With the gradual popularization of hydrogen fuel cell vehicles (HFCVs), the construction and planning of hydrogen refueling stations (HRSs) are increasingly important. Taking operational HRSs in China’s coastal and major cities as examples, we consider the main factors affecting the site selection of HRSs in China from the three aspects of economy, technology and society to establish a site selection evaluation system for hydrogen refueling stations and determine the weight of each index through the analytic hierarchy process (AHP). Then, combined with fuzzy comprehensive evaluation (FCE) method and artificial neural network model (ANN), FCE method is used to evaluate HRS in operation in China’s coastal areas and major cities, and we used the resulting data obtained from the comprehensive evaluation as the training data to train the neural network. So, an intelligent site selection model for HRSs based on fuzzy comprehensive evaluation and artificial neural network model (FCE-ANN) is proposed. The planned HRSs in Shanghai are evaluated, and an optimal site selection of the HRS is obtained. The results show that the optimal HRSs site selected by the FCE-ANN model is consistent with the site selection obtained by the FCE method, and the accuracy of the FCE-ANN model is verified. The findings of this study may provide some guidelines for policy makers in planning the hydrogen refueling stations. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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15 pages, 3204 KiB

Open AccessArticle

Economic Dispatch Model of Nuclear High-Temperature Reactor with Hydrogen Cogeneration in Electricity Market

by James Richards, Cristian Rabiti, Hiroyuki Sato, Xing L. Yan and Nolan Anderson

Energies 2021, 14(24), 8289; https://doi.org/10.3390/en14248289 - 9 Dec 2021

Cited by 2 | Viewed by 2088

Abstract

Hydrogen produced without carbon emissions could be a useful fuel as nations look to decarbonize their electricity, transport, and industry sectors. Using the iodine–sulfur (IS) cycle coupled with a nuclear heat source is one method for producing hydrogen without the use of fossil [...] Read more.

Hydrogen produced without carbon emissions could be a useful fuel as nations look to decarbonize their electricity, transport, and industry sectors. Using the iodine–sulfur (IS) cycle coupled with a nuclear heat source is one method for producing hydrogen without the use of fossil fuels. An economic dispatch model was developed for a nuclear-driven IS system to determine hydrogen sale prices that would make such a system profitable. The system studied is the HTTR-GT/H₂, a design for power and hydrogen cogeneration at the Japan Atomic Energy Agency’s High Temperature Engineering Test Reactor. This study focuses on the development of the economic model and the role that input data plays in the final calculated values. Using a historical price duration curve shows that the levelized cost of hydrogen (LCOH) or breakeven sale price of hydrogen would need to be 98.1 JPY/m³ or greater. Synthetic time histories were also used and found the LCOH to be 67.5 JPY/m³. The price duration input was found to have a significant effect on the LCOH. As such, great care should be used in these economic dispatch analyses to select reasonable input assumptions. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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17 pages, 4368 KiB

Open AccessArticle

CFD Simulation of Hydrogen Generation and Methane Combustion Inside a Water Splitting Membrane Reactor

by Te Zhao, Chusheng Chen and Hong Ye

Energies 2021, 14(21), 7175; https://doi.org/10.3390/en14217175 - 1 Nov 2021

Cited by 7 | Viewed by 1853

Abstract

Hydrogen production from water splitting remains difficult due to the low equilibrium constant (e.g., Kp ≈ 2 × 10⁻⁸ at 900 °C). The coupling of methane combustion with water splitting in an oxygen transport membrane reactor can shift the water splitting equilibrium [...] Read more.

Hydrogen production from water splitting remains difficult due to the low equilibrium constant (e.g., Kp ≈ 2 × 10⁻⁸ at 900 °C). The coupling of methane combustion with water splitting in an oxygen transport membrane reactor can shift the water splitting equilibrium toward dissociation by instantaneously removing O₂ from the product, enabling the continuous process of water splitting and continuous generation of hydrogen, and the heat required for water splitting can be largely compensated for by methane combustion. In this work, a CFD simulation model for the coupled membrane reactor was developed and validated. The effects of the sweep gas flow rate, methane content and inlet temperature on the reactor performance were investigated. It was found that coupling of methane combustion with water splitting could significantly improve the hydrogen generation capacity of the membrane reactor. Under certain conditions, the average hydrogen yield with methane combustion could increase threefold compared to methods that used no coupling of combustion. The methane conversion decreases while the hydrogen yield increases with the increase in sweep gas flow rate or methane content. Excessive methane is required to ensure the hydrogen yield of the reactor. Increasing the inlet temperature can increase the membrane temperature, methane conversion, oxygen permeation rate and hydrogen yield. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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17 pages, 54529 KiB

Open AccessReview

Recent Achievements in Microalgal Photobiological Hydrogen Production

by Eleftherios Touloupakis, Cecilia Faraloni, Ana Margarita Silva Benavides and Giuseppe Torzillo

Energies 2021, 14(21), 7170; https://doi.org/10.3390/en14217170 - 1 Nov 2021

Cited by 42 | Viewed by 4480

Abstract

It is well known that over the last 60 years the trend of long-lived greenhouse gas emissions have shown a strong acceleration. There is an increasing concern and a mounting opposition by public opinion to continue with the use of fossil energy. Western [...] Read more.

It is well known that over the last 60 years the trend of long-lived greenhouse gas emissions have shown a strong acceleration. There is an increasing concern and a mounting opposition by public opinion to continue with the use of fossil energy. Western countries are presently involved in a so-called energy transition with the objective of abandoning fossil energy for renewable sources. In this connection, hydrogen can play a central role. One of the sustainable ways to produce hydrogen is the use of microalgae which possess two important natural catalysts: photosystem II and hydrogenase, used to split water and to combine protons and electrons to generate gaseous hydrogen, respectively. For about 20 years of study on photobiological hydrogen production, our scientific hopes were based on the application of the sulfur protocol, which indisputably represented a very important advancement in the field of hydrogen production biotechnology. However, as reported in this review, there is increasing evidence that this strategy is not economically viable. Therefore, a change of paradigm for the photobiological production of hydrogen based on microalgae seems mandatory. This review points out that an increasing number of microalgal strains other than Chlamydomonas reinhardtii are being tested and are able to produce sustainable amount of hydrogen without nutrient starvation and to fulfill this goal including the application of co-cultures. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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25 pages, 4591 KiB

Open AccessReview

Modern Trends in Design of Catalysts for Transformation of Biofuels into Syngas and Hydrogen: From Fundamental Bases to Performance in Real Feeds

by Vladislav Sadykov, Mikhail Simonov, Nikita Eremeev and Natalia Mezentseva

Energies 2021, 14(19), 6334; https://doi.org/10.3390/en14196334 - 4 Oct 2021

Cited by 3 | Viewed by 2036

Abstract

This review considers problems related to design of efficient structured catalysts for natural gas and biofuels transformation into syngas. Their active components are comprised of fluorite, perovskite and spinel oxides or their nanocomposites (both bulk and supported on high surface area Mg-doped alumina [...] Read more.

This review considers problems related to design of efficient structured catalysts for natural gas and biofuels transformation into syngas. Their active components are comprised of fluorite, perovskite and spinel oxides or their nanocomposites (both bulk and supported on high surface area Mg-doped alumina or MgAl₂O₄) promoted by platinum group metals, nickel and their alloys. A complex of modern structural, spectroscopic and kinetic methods was applied to elucidate atomic-scale factors controlling their performance and stability to coking, such as dispersion of metals/alloys, strong metal-support interaction and oxygen mobility/reactivity as dependent upon their composition and synthesis procedures. Monolithic catalysts comprised of optimized active components loaded on structured substrates with a high thermal conductivity demonstrated high activity and stability to coking in processes of natural gas and biofuels reforming into syngas. A pilot-scale axial reactor equipped with the internal heat exchanger and such catalysts allowed to efficiently convert into syngas the mixture of natural gas, air and liquid biofuels in the autothermal reforming mode at low (~50–100 °C) inlet temperatures and GHSV up to 40,000 h⁻¹. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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19 pages, 5605 KiB

Open AccessArticle

Parametric Study for Thermal and Catalytic Methane Pyrolysis for Hydrogen Production: Techno-Economic and Scenario Analysis

by Seunghyun Cheon, Manhee Byun, Dongjun Lim, Hyunjun Lee and Hankwon Lim

Energies 2021, 14(19), 6102; https://doi.org/10.3390/en14196102 - 24 Sep 2021

Cited by 13 | Viewed by 4014

Abstract

As many countries have tried to construct a hydrogen (H₂) society to escape the conventional energy paradigm by using fossil fuels, methane pyrolysis (MP) has received a lot of attention owing to its ability to produce H₂ with no CO [...] Read more.

As many countries have tried to construct a hydrogen (H₂) society to escape the conventional energy paradigm by using fossil fuels, methane pyrolysis (MP) has received a lot of attention owing to its ability to produce H₂ with no CO₂ emission. In this study, a techno-economic analysis including a process simulation, itemized cost estimation, and sensitivity and scenario analysis was conducted for the system of thermal-based and catalyst-based MP (TMP-S1 and CMP-S2), and the system with the additional H₂ production processes of carbon (C) gasification and water–gas shift (WGS) reaction (TMPG-S3 and CMPG-S4). Based on the technical performance expressed by H₂ and C production rate, the ratio of H₂ combusted to supply the heat required and the ratio of reactants for the gasifier (C, Air, and water (H₂O)), unit H₂ production costs of USD 2.14, 3.66, 3.53, and 3.82 kgH₂⁻¹ from TMP-S1, CMP-S2, TMPG-S3, and CMPG-S4, respectively, were obtained at 40% H₂ combusted and a reactants ratio for C-Air-H₂O of 1:1:2. Moreover, trends of unit H₂ production cost were obtained and key economic parameters of the MP reactor, reactant, and C selling price were represented by sensitivity analysis. In particular, economic competitiveness compared with commercialized H₂ production methods was reported in the scenario analysis for the H₂ production scale and C selling price. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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18 pages, 7241 KiB

Open AccessArticle

Optimization of a Mixed Refrigerant Based H₂ Liquefaction Pre-Cooling Process and Estimate of Liquefaction Performance with Varying Ambient Temperature

by Steven Jackson and Eivind Brodal

Energies 2021, 14(19), 6090; https://doi.org/10.3390/en14196090 - 24 Sep 2021

Cited by 7 | Viewed by 2477

Abstract

Hydrogen used as an energy carrier can provide an important route to the decarbonization of energy supplies, but realizing this opportunity will require both significantly increased production and transportation capacity. One route to increased transportation capacity is the shipping of liquid hydrogen, but [...] Read more.

Hydrogen used as an energy carrier can provide an important route to the decarbonization of energy supplies, but realizing this opportunity will require both significantly increased production and transportation capacity. One route to increased transportation capacity is the shipping of liquid hydrogen, but this requires an energy-intensive liquefaction step. Recent study work has shown that the energy required in this process can be reduced through the implementation of new and improved process designs, but since all low-temperature processes are affected by the available heat-sink temperature, local ambient conditions will also have an impact. The objective of this work is to identify how the energy consumption associated with hydrogen liquefaction varies with heat-sink temperature through the optimization of design parameters for a next-generation mixed refrigerant based hydrogen liquefaction process. The results show that energy consumption increases by around 20% across the cooling temperature range 5 to 50 °C. Considering just the range 20 to 30 °C, there is a 5% increase, illustrating the significant impact ambient temperature can have on energy consumption. The implications of this work are that the modelling of different liquified hydrogen based energy supply chains should take the impact of ambient temperature into account. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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16 pages, 2992 KiB

Open AccessReview

A Review of Enhancement of Biohydrogen Productions by Chemical Addition Using a Supervised Machine Learning Method

by Yiyang Liu, Jinze Liu, Hongzhen He, Shanru Yang, Yixiao Wang, Jin Hu, Huan Jin, Tianxiang Cui, Gang Yang and Yong Sun

Energies 2021, 14(18), 5916; https://doi.org/10.3390/en14185916 - 17 Sep 2021

Cited by 19 | Viewed by 2898

Abstract

In this work, the impact of chemical additions, especially nano-particles (NPs), was quantitatively analyzed using our constructed artificial neural networks (ANNs)-response surface methodology (RSM) algorithm. Fe-based and Ni-based NPs and ions, including Mg²⁺, Cu²⁺, Na⁺, NH₄ [...] Read more.

In this work, the impact of chemical additions, especially nano-particles (NPs), was quantitatively analyzed using our constructed artificial neural networks (ANNs)-response surface methodology (RSM) algorithm. Fe-based and Ni-based NPs and ions, including Mg²⁺, Cu²⁺, Na⁺, NH₄⁺, and K⁺, behave differently towards the response of hydrogen yield (HY) and hydrogen evolution rate (HER). Manipulating the size and concentration of NPs was found to be effective in enhancing the HY for Fe-based NPs and ions, but not for Ni-based NPs and ions. An optimal range of particle size (86–120 nm) and Ni-ion/NP concentration (81–120 mg L⁻¹) existed for HER. Meanwhile, the manipulation of the size and concentration of NPs was found to be ineffective for both iron and nickel for the improvement of HER. In fact, the variation in size of NPs for the enhancement of HY and HER demonstrated an appreciable difference. The smaller (less than 42 nm) NPs were found to definitely improve the HY, whereas for the HER, the relatively bigger size of NPs (40–50 nm) seemed to significantly increase the H₂ evolution rate. It was also found that the variations in the concentration of the investigated ions only statistically influenced the HER, not the HY. The level of response (the enhanced HER) towards inputs was underpinned and the order of significance towards HER was identified as the following: Na⁺ > Mg²⁺ > Cu²⁺ > NH₄⁺ > K⁺. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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22 pages, 370 KiB

Open AccessReview

Intermetallic Compounds Synthesized by Mechanical Alloying for Solid-State Hydrogen Storage: A Review

by Yuchen Liu, Djafar Chabane and Omar Elkedim

Energies 2021, 14(18), 5758; https://doi.org/10.3390/en14185758 - 13 Sep 2021

Cited by 30 | Viewed by 4573

Abstract

Hydrogen energy is a very attractive option in dealing with the existing energy crisis. For the development of a hydrogen energy economy, hydrogen storage technology must be improved to over the storage limitations. Compared with traditional hydrogen storage technology, the prospect of hydrogen [...] Read more.

Hydrogen energy is a very attractive option in dealing with the existing energy crisis. For the development of a hydrogen energy economy, hydrogen storage technology must be improved to over the storage limitations. Compared with traditional hydrogen storage technology, the prospect of hydrogen storage materials is broader. Among all types of hydrogen storage materials, solid hydrogen storage materials are most promising and have the most safety security. Solid hydrogen storage materials include high surface area physical adsorption materials and interstitial and non-interstitial hydrides. Among them, interstitial hydrides, also called intermetallic hydrides, are hydrides formed by transition metals or their alloys. The main alloy types are A

_{2}

B, AB, AB

_{2}

, AB

_{3}

, A

_{2}

B

_{7}

, AB

_{5}

, and BCC. A is a hydride that easily forms metal (such as Ti, V, Zr, and Y), while B is a non-hydride forming metal (such as Cr, Mn, and Fe). The development of intermetallic compounds as hydrogen storage materials is very attractive because their volumetric capacity is much higher (80–160 kgH

_{2}

m

^{- 3}

) than the gaseous storage method and the liquid storage method in a cryogenic tank (40 and 71 kgH

_{2}

m

^{- 3}

). Additionally, for hydrogen absorption and desorption reactions, the environmental requirements are lower than that of physical adsorption materials (ultra-low temperature) and the simplicity of the procedure is higher than that of non-interstitial hydrogen storage materials (multiple steps and a complex catalyst). In addition, there are abundant raw materials and diverse ingredients. For the synthesis and optimization of intermetallic compounds, in addition to traditional melting methods, mechanical alloying is a very important synthesis method, which has a unique synthesis mechanism and advantages. This review focuses on the application of mechanical alloying methods in the field of solid hydrogen storage materials. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

11 pages, 3096 KiB

Open AccessArticle

A Highly Selective Novel Green Cation Exchange Membrane Doped with Ceramic Nanotubes Material for Direct Methanol Fuel Cells

by Marwa H. Gouda, Tamer M. Tamer and Mohamed S. Mohy Eldin

Energies 2021, 14(18), 5664; https://doi.org/10.3390/en14185664 - 9 Sep 2021

Cited by 4 | Viewed by 1890

Abstract

Herein, a pair of inexpensive and eco-friendly polymers were blended and formulated based on poly (ethylene oxide) (PEO) and poly (vinyl alcohol) (PVA). FTIR, XRD, EDX and TEM techniques were used to describe a Phosphated titanium oxide (PO₄TiO₂) nanotube [...] Read more.

Herein, a pair of inexpensive and eco-friendly polymers were blended and formulated based on poly (ethylene oxide) (PEO) and poly (vinyl alcohol) (PVA). FTIR, XRD, EDX and TEM techniques were used to describe a Phosphated titanium oxide (PO₄TiO₂) nanotube synthesised using a straightforward impregnation-calcination procedure. For the first time, the produced nanoparticles were inserted as a doping agent into this polymeric matrix at a concentration of (1–3) wt.%. FTIR, TGA, DSC and XRD were used to identify the formed composite membranes. Furthermore, because there are more hydrogen bonds generated between the polymer’s functional groups and oxygen functional groups PO₄TiO₂, oxidative stability and tensile strength are improved with increasing doping addition and obtain better results than Nafion117. The permeability of methanol reduced as the weight % of PO₄TiO₂ increased. In addition, the ionic conductivity of the membrane with 3 wt.% PO₄-TiO₂ is raised to (28 mS cm⁻¹). The optimised membrane (PVA/PEO/PO₄TiO₂-3) had a higher selectivity (6.66 × 10⁵ S cm⁻³ s) than Nafion117 (0.24 × 10⁵ S cm⁻³ s) and can be used as a proton exchange membrane in the development of green and low-cost DMFCs. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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21 pages, 3514 KiB

Open AccessArticle

An Experimental Study of the Possibility of In Situ Hydrogen Generation within Gas Reservoirs

by Pavel Afanasev, Evgeny Popov, Alexey Cheremisin, Roman Berenblyum, Evgeny Mikitin, Eduard Sorokin, Alexey Borisenko, Viktor Darishchev, Konstantin Shchekoldin and Olga Slavkina

Energies 2021, 14(16), 5121; https://doi.org/10.3390/en14165121 - 19 Aug 2021

Cited by 21 | Viewed by 4142

Abstract

Hydrogen can be generated in situ within reservoirs containing hydrocarbons through chemical reactions. This technology could be a possible solution for low-emission hydrogen production due to of simultaneous CO₂ storage. In gas fields, it is possible to carry out the catalytic methane [...] Read more.

Hydrogen can be generated in situ within reservoirs containing hydrocarbons through chemical reactions. This technology could be a possible solution for low-emission hydrogen production due to of simultaneous CO₂ storage. In gas fields, it is possible to carry out the catalytic methane conversion (CMC) if sufficient amounts of steam, catalyst, and heat are ensured in the reservoir. There is no confirmation of the CMC’s feasibility at relatively low temperatures in the presence of core (reservoir rock) material. This study introduces the experimental results of the first part of the research on in situ hydrogen generation in the Promyslovskoye gas field. A set of static experiments in the autoclave reactor were performed to study the possibility of hydrogen generation under reservoir conditions. It was shown that CMC can be realized in the presence of core and ex situ prepared Ni-based catalyst, under high pressure up to 207 atm, but at temperatures not lower than 450 °C. It can be concluded that the crushed core model improves the catalytic effect but releases carbon dioxide and light hydrocarbons, which interfere with the hydrogen generation. The maximum methane conversion rate to hydrogen achieved at 450 °C is 5.8%. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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22 pages, 1296 KiB

Open AccessFeature PaperArticle

The Impact of Economic, Energy, and Environmental Factors on the Development of the Hydrogen Economy

by Justyna Cader, Renata Koneczna and Piotr Olczak

Energies 2021, 14(16), 4811; https://doi.org/10.3390/en14164811 - 7 Aug 2021

Cited by 39 | Viewed by 5739

Abstract

This article attempts to model interdependencies between socio-economic, energy, and environmental factors with selected data characterizing the development of the hydrogen economy. The study applies Spearman’s correlation and a linear regression model to estimate the influence of gross domestic product, population, final energy [...] Read more.

This article attempts to model interdependencies between socio-economic, energy, and environmental factors with selected data characterizing the development of the hydrogen economy. The study applies Spearman’s correlation and a linear regression model to estimate the influence of gross domestic product, population, final energy consumption, renewable energy, and CO₂ emission on chosen hydrogen indicators—production, patents, energy technology research, development, and demonstration budgets. The study was conducted in nine countries selected for their actions towards a hydrogen economy based on analyses of national strategies, policies, research and development programs, and roadmaps. The results confirm the statistically significant impact of the chosen indicators, which are the drivers for the development of the hydrogen economy from 2008 to 2018. Moreover, the empirical results show that different characteristics in each country contribute to the development of the hydrogen economy vision. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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23 pages, 7339 KiB

Open AccessArticle

Thermal Efficiency and Economics of a Boil-Off Hydrogen Re-Liquefaction System Considering the Energy Efficiency Design Index for Liquid Hydrogen Carriers

by Minsoo Choi, Wongwan Jung, Sanghyuk Lee, Taehwan Joung and Daejun Chang

Energies 2021, 14(15), 4566; https://doi.org/10.3390/en14154566 - 28 Jul 2021

Cited by 10 | Viewed by 3449

Abstract

This study analyzes the thermodynamic, economic, and regulatory aspects of boil-off hydrogen (BOH) in liquid hydrogen (LH₂) carriers that can be re-liquefied using a proposed re-liquefaction system or used as fuel in a fuel cell stack. Five LH₂ carriers sailing [...] Read more.

This study analyzes the thermodynamic, economic, and regulatory aspects of boil-off hydrogen (BOH) in liquid hydrogen (LH₂) carriers that can be re-liquefied using a proposed re-liquefaction system or used as fuel in a fuel cell stack. Five LH₂ carriers sailing between two designated ports are considered in a case study. The specific energy consumption of the proposed re-liquefaction system varies from 8.22 to 10.80 kWh/kg as the re-liquefaction-to-generation fraction (R/G fraction) is varied. The economic evaluation results show that the cost of re-liquefaction decreases as the re-liquefied flow rate increases and converges to 1.5 $/kg at an adequately large flow rate. Three energy efficient design index (EEDI) candidates are proposed to determine feasible R/G fractions: an EEDI equivalent to that of LNG carriers, an EEDI that considers the energy density of LH₂, and no EEDI restrictions. The first EEDI candidate is so strict that the majority of the BOH should be used as fuel. In the case of the second EEDI candidate, the permittable R/G fraction is between 25% and 33%. If the EEDI is not applied for LH₂ carriers, as in the third candidate, the specific life-cycle cost decreases to 67% compared with the first EEDI regulation. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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17 pages, 6267 KiB

Open AccessArticle

Heat Transfer Analysis in Supercritical Hydrogen of Decoupled Poisoned Hydrogen Moderator with Non-Uniform Heat Source of Chinese Spallation Neutron Source

by Jianfei Tong, Lingbo Zhu, Yiping Lu, Tianjiao Liang, Youlian Lu, Songlin Wang, Chaoju Yu, Shikui Dong and Heping Tan

Energies 2021, 14(15), 4547; https://doi.org/10.3390/en14154547 - 27 Jul 2021

Cited by 1 | Viewed by 1718

Abstract

The flow field distribution and thermal properties of supercritical hydrogen are crucial factors affecting the quality of neutrons output from spallation neutron source, which may contribute to the optimization design of the moderator. Several sensitivity studies on affecting heat transfer characteristics of liquid [...] Read more.

The flow field distribution and thermal properties of supercritical hydrogen are crucial factors affecting the quality of neutrons output from spallation neutron source, which may contribute to the optimization design of the moderator. Several sensitivity studies on affecting heat transfer characteristics of liquid hydrogen inside a moderator were executed, and a choice was made to use a computational fluid dynamics method for numerical simulation. The sensitivity degree of factors affecting the heat transfer characteristics of liquid hydrogen are in sequence of inlet mass flow, beam power and operating pressure. Especially when the beam power is 500 kW (the temperature range of liquid hydrogen is about 20~30 K); where the effect of mass flow rate is remarkable, the cooling effect is best in the range of 60~90 g/s × 394 mm². Meanwhile, the maximum temperature of liquid hydrogen is close to the bottom recirculation zone due to the influence of the flow field and the heat deposition distribution of the poisoned plate. The effect of variable pressure on the temperature of liquid hydrogen is not significant, whereas the sudden rise of wall temperature is observed near the large specific heat region of 15 bar. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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22 pages, 5026 KiB

Open AccessArticle

Model-Based System Performance Analysis of a Solid Oxide Fuel Cell System with Anode Off-Gas Recirculation

by Eun-Jung Choi, Sangseok Yu, Ji-Min Kim and Sang-Min Lee

Energies 2021, 14(12), 3607; https://doi.org/10.3390/en14123607 - 17 Jun 2021

Cited by 7 | Viewed by 2729

Abstract

Designing proper solid oxide fuel cell (SOFC) system configurations is essential for their high efficiency. The present study analyzes the performance improvement of the SOFC system with anode off-gas recirculation (AOGR). Two AOGR configurations are suggested. Depending on the heat flows of off [...] Read more.

Designing proper solid oxide fuel cell (SOFC) system configurations is essential for their high efficiency. The present study analyzes the performance improvement of the SOFC system with anode off-gas recirculation (AOGR). Two AOGR configurations are suggested. Depending on the heat flows of off gases, the configurations are called AOGR #1 and #2, respectively. Additionally, a reference system is examined for comparison. This study aims to numerically evaluate the characteristics and performance of each system under various operating conditions such as fuel and air utilization factors. The operating current density and steam to carbon ratio are fixed at 0.3 A/cm² and 2.5, respectively. The results indicate that the system performance shows a large difference depending on the system configurations. The SOFC system with AOGR has better performance than the reference system under the operating conditions considered in this paper. However, it is also revealed that depending on the system configuration and operating conditions, AOGR can be effective or ineffective for system performance. Therefore, a deliberate operating strategy for AOGR systems needs to be developed based on the load conditions. Full article

(This article belongs to the Topic Hydrogen Energy Technologies)

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