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Biohythane, the promising gaseous biofuel, can be produced by the recirculated two-phase anaerobic digestion (R-TPAD). The effect of hydraulic retention time (HRT) as 30, 20 and 10 days on biohythane production via R-TPAD (recirculation ratio = 0.4) was investigated with co-digestion of food waste and paper waste. The results showed that HRTs of 30 and 20 days maintained stable performance for R-TPAD but HRT of 10 days led to the final decrease in biogas production. The failure in the end was attributed to the wash-out of microbes. The removal efficiencies for COD and carbohydrates were decreased by short HRTs while for VS it remained relatively stable at about 75.7 ± 4.0%. All through the operation, acidogenic phase and methanogenic phase were separated stably and butyrate pathway was the dominant pathway for hydrogen fermentation in the first stage. The microbial community in the first stage reached the highest diversity when total HRT was 20 days, where the hydrogen production rate was the highest. The genera Lactobacillus and Caproiciproducens kept dominating the dark fermentation in the acidogenic phase, and Ruminococcus and Methanosarcina were decreasing in the methanogenic phase. The biohythane yields were 411 mL/g-VS fed , 332 mL/g-VS fed and 253 mL/g-VS fed , respectively, where the H 2 contents were 18.4%, 14.7% and 8.8%, respectively. [Display omitted] • The R-TPAD system (R = 0.4) was operated for biohythane production. • R-TPAD operated under HRTs of 30 and 20 maintained stable performance. • Organic removals and biohythane yields were lowered by short HRTs. • Different microbial communities were identified by co-occurrence network. • Biohythane yields affected by different parameters were discussed. [ABSTRACT FROM AUTHOR]

Paper industries are water-intensive industries that produce large amount of wastewater containing dyes, toxicity and high nutrient content. These industries require sustainable technology for their waste disposal and MEC could be one of them. However, effective MEC operation at neutral pH and ambient temperature requires economical and efficient cathodes that are capable to treat indusial wastewater along with recovery of energy/biohydrogen. Co-deposits of Nickel, Nickel–Cobalt and Nickel–Cobalt–Phosphorous on the surface of SS and Cu base metals distinctly were used as cathodes in MEC for the concurrent treatment of real paper industry wastewater and biohydrogen production. MECs were utilized in batch mode at neutral pH, applied voltage of 0.6 V and 30 ± 2 °C temperature with paper industry wastewater and activated sludge as microbial sources. The fabricated Nickel–Cobalt–Phosphorous gives the higher hydrogen production rate of 0.16 ± 0.002 m3(H 2) m−3d−1 and 0.14 ± 0.002 m3(H 2) m −3d −1 respectively, with ~33–42 % treatment efficiency for a 500 ml wastewater in 7-day batch cycle in both the cases; while it is lowest in the case of the control cathodes (SS1 (0.07 ± 0.002 m3(H 2) m−3d−1) & Cu1 (0.06 ± 0.004 m3(H 2) m−3d−1)). It was also found that fabricated cathodes have the capability to treat industrial wastewater at ambient conditions efficiently with higher energy recovery. Prepared cathodes show enhanced hydrogen production and treatment efficiency as well as are competitive to some reported literature. [Display omitted] • The fabricated cathodes exhibited higher electrochemical catalytic activity in real paper industry wastewater. • MECs were used concurrently for energy recovery and treatment of real paper industry wastewater. • Reaction inside MECs can be enhanced by depositing Ni–Co–P based particle on electrode surface. • Ni-Co-P co-deposits attained the maximum H 2 production rate of 0.16-0.06 ±0.002 m3(H 2) m-3d-1 with ~42 % COD reduction. • Higher biohydrogen production, cathodic efficiency and energy recovery were obtained with co –deposited cathode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A paper-based photoanode is developed for photoelectrochemical water splitting. • MoSe 2 nanosheet anchored CdS-ZnO array functional paper is prepared. • Tandem Z-scheme configuration with double IEFs and photothermal effect are integrated. • The flexible photoanode achieves admirable solar water splitting performance. Rational design of photoelectrode architectures is deemed as an effective solution to enhance efficiency of photoelectrochemical water splitting for conquering increasingly prominent environmental problems. Herein, a programmable flexible photoanode with built-in tandem Z-scheme configuration fabricated by in-situ growth of MoSe 2 -CdS-ZnO array with ultrathin nanosheet-interlaced-nanorod structure on the Au paper electrode, is firstly reported. By taking advantages of the interwoven nanonetwork structure, high conductivity as well as larger porosity of the as-fabricated Au paper electrode, a stable light-harvesting paper chip with fast transfer/separate mediators of the charge/carriers is thus integrated. By virtue of double internal electric fields (IEFs) and photothermal effect, the developed MoSe 2 -CdS-ZnO photoanode exhibits incident-photon-to-current efficiency of 52 % under 460 nm of light irradiation, and the current density reaches 2.4 mA cm−2 at 0.3 V versus normal hydrogen electrode, which is comparable with respect to current state-of-the-art "type-II-scheme", "surface-scheme", and cocatalyst-free photocatalysts (0.03–2.4 mA cm−2). Consequently, the paper-based photoanode achieves admirable photoelectrocatalytic hydrogen generation property (39.7 μmol cm−2 h-1). The synergistic effect of tailorable tandem Z-scheme configuration with double IEFs and delineating of 3D cross-linked network structure of the proposed photoanode in this work may open an avenue for constructing high-performance photoelectrochemical water splitting devices. [ABSTRACT FROM AUTHOR]

To improve the hydrogen detection performance, a flexible palladium-based hydrogen sensor was designed and fabricated on normal photocopy paper. The paper substrate offers advantages such as light weight, low cost, flexibility and unique surface texture. A conventional vacuum evaporation technique was utilized for 60 nm palladium deposition on the paper and glass substrates. The unique surface texture of the paper effectively increased the surface area to volume ratio for the sensing element, which achieved a higher gas response with faster speed than the glass-based sensor. In addition, we investigated the temperature impacts on sensing performance of the paper-based hydrogen sensor at room temperature and 50 °C. Furthermore, the flexibility test results of the paper-based hydrogen sensor showed that the sensing performances were impervious to mechanical bending of 5.7°. [ABSTRACT FROM AUTHOR]

This paper presents the results of a severe accident parametric sensitivity study performed on a model of a generic integral pressurized water reactor (iPWR). The analyzed sequence is a loss of coolant accident (LOCA)-type scenario, postulating that safety systems are not available. In this work, a MELCOR 2.2 input deck of a generic iPWR was developed based on publicly available data. The iPWR used in this work is a generic iPWR with a thermal power of about 160 MWth, characterized by a compact steam generator and a submerged containment configuration. A hypothetical scenario considered in this work was an unmitigated small break LOCA leading to a severe accident with partial core degradation, due to the postulated assumptions. In the presented paper, 16 sensitivity cases were calculated and analyzed, focusing mainly on heat transfer, decay heat, and core degradation parameters. The selected parameters and their combination caused partial core degradation and showed significant differences in investigated variables such as core degradation and hydrogen generation, as well as examined CPU time consumption. This a preparatory work performed in the framework of the Horizon Euratom SASPAM-SA project, which aims to investigate the applicability and transfer of the operating large light-water reactor knowledge and know-how to the iPWR, taking into account European licensing analysis needs for the severe accident and emergency planning zone. [ABSTRACT FROM AUTHOR]

As new sources of energy and advanced technologies are used, there is a continuous evolution in energy supply, demand, and distribution. Advanced nuclear reactors and clean hydrogen have the opportunity to scale together and diversify the hydrogen production market away from fossil fuel-based production. Nevertheless, the technical uncertainties surrounding nuclear hydrogen processes necessitate thorough research and a solid development effort. This paper aims to position pink hydrogen for nuclear hydrogen production at the forefront of sustainable energy-related solutions by offering a comprehensive review of recent advancements in nuclear hydrogen production, covering both research endeavors and industrial applications. It delves into various pink hydrogen generation methodologies, elucidating their respective merits and challenges. Furthermore, this paper analyzes the evolving landscape of pink hydrogen in terms of its levelized cost by comparatively assessing different production pathways. By synthesizing insights from academic research and industrial practices, this paper provides valuable perspectives for stakeholders involved in shaping the future of nuclear hydrogen production. [ABSTRACT FROM AUTHOR]

Highly dispersed Cobalt doped ZnS nanostructures were successfully fabricated on the surfaces of graphene sheets via a simple hydrothermal method. X-ray diffraction (XRD), X-ray photocurrent spectroscopy (XPS), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were utilized to analyze the structural characteristics of the cobalt doped ZnS decorated with graphene Co x Zn 1 - x S rGO nanostructures (NSs). UV-visible optical absorption (UV-vis) studies were conducted to investigate their optical properties. In laboratory studies utilizing water and visible light, the photocatalytic activity of Co x Zn 1 - x S rGO NSs at (x = 0, 1, 2, 4 and 6 atm.%) were evaluated. Graphite Oxide (GO) was successfully transformed into sheets of graphene and Co x Zn 1 - x S rGO NSs possessed a crystalline structure according to the findings of XRD, RS and FTIR analysis. SEM investigation showed graphene sheets enhanced with ZnS NSs possessed cuboidal, spheroidal form of structure and displayed a paper like appearance. UV-vis confirmed a noticeable rapid increase in transmittance along the UV wavelength area and confirmed a highly transparent NSs in the wavelength range of (180-800 nm). Calculations using density functional theory (DFT) revealed that the Co NSs have more negative conduction bands than ZnS, allowing for effective electron transfer from cobalt to ZnS and exhibiting a band gap decrease as Co content increased. The Co 0.04 Zn 0.96 S rGO NSs sample had the highest photocatalytic activity, measured at 7648.9 μ mol h - 1 . A combination of improved dispersion properties, greater surface area, increased absorption and enhanced transfer of photogenerated electrons, Co x Zn 1 - x S rGO NSs increased the photocatalytic hydrogen generation activity. [ABSTRACT FROM AUTHOR]

Most renewable energy sources are intermittent and seasonal, making energy storage and consumption problematic. Hydrogen gas can save and convey chemical energy, making it a promising sustainable energy source. Electrochemical water electrolysis technology's sustainable and efficient hydrogen gas production attracts global attention. Higher hydrogen production rates enhance hydrogen volumetric energy capacity by storing intermittent hydrogen gas in high-pressure tanks. Pressurized storage tanks are cost-effective and efficient. Hydrogen gas may be stored economically and efficiently in pressurized tanks, making electrochemical water electrolysis a sustainable energy source. This paper introduced hydrogen as an alternative to natural gas, detailed water electrolysis technologies for hydrogen production, and highlighted how they can manufacture hydrogen efficiently and cost-effectively. The theoretical volume of gaseous hydrogen and oxygen that could be produced by electrolyzing water under typical temperature and pressure (STP) circumstances, assuming a 100% efficiency rate of the process. Since there are always two moles of hydrogen produced by electrolysis and one mole of gas occupies the same volume, the volume of hydrogen developed from water is twice that of oxygen. The volume of liberated oxygen is 0.21 (L/min), and the volume of liberated hydrogen is 0.42 (L/min) with a current density of 30 A, for instance, the tracer's diffusion coefficient for all conceivable flow rates. A maximum value of 90 liters per hour was determined to be the threshold at which the diffusion coefficient increased with increasing flow rate. It would appear that the diffusion coefficient remains unchanged at flow rates greater than 90 liters per hour. [ABSTRACT FROM AUTHOR]

The global issue of climate change caused by humans and its inextricable linkage to our present and future energy demand presents the biggest challenge facing our globe. Hydrogen has been introduced as a new renewable energy resource. It is envisaged to be a crucial vector in the vast low-carbon transition to mitigate climate change, minimize oil reliance, reinforce energy security, solve the intermittency of renewable energy resources, and ameliorate energy performance in the transportation sector by using it in energy storage, energy generation, and transport sectors. Many technologies have been developed to generate hydrogen. The current paper presents a review of the current and developing technologies to produce hydrogen from fossil fuels and alternative resources like water and biomass. The results showed that reformation and gasification are the most mature and used technologies. However, the weaknesses of these technologies include high energy consumption and high carbon emissions. Thermochemical water splitting, biohydrogen, and photo-electrolysis are long-term and clean technologies, but they require more technical development and cost reduction to implement reformation technologies efficiently and on a large scale. A combination of water electrolysis with renewable energy resources is an ecofriendly method. Since hydrogen is viewed as a considerable game-changer for future fuels, this paper also highlights the challenges facing hydrogen generation. Moreover, an economic analysis of the technologies used to generate hydrogen is carried out in this study. [ABSTRACT FROM AUTHOR]

The design and development of efficient nitride photocatalysts have attracted much attention. Herein, two-dimensional mesoporous Ta 3 N 5 is successfully synthesized through a simple sol-gel process with filter paper as a biological template and a combination of vacuum nitriding reactions. The prepared Ta 3 N 5 shows a wide light response range up to the near infrared (NIR) region due to the nitrogen vacancies generated from substitution of N3− for O2− ions during vacuum nitridation. Significantly, such a narrow bandgap (∼1.99 eV) still satisfies the redox potential of water splitting in thermodynamics. The experimental results show that the Ta 3 N 5 photocatalyst exhibits an enhanced hydrogen production rate of 34.6 μmol h−1 g−1, which is 3.9 and 2.1 times higher than that of Ta 2 O 5 and partial nitridation of Ta 2 O 5 (N–Ta 2 O 5), respectively. This enhanced photocatalytic performance could be attributed to the high specific surface area to provide reactive active sites, substitution of N3− for O2− ions to optimize the band structure, and special two-dimensional mesoporous structure to shorten the charge transfer distance. This work provides a new perspective for the preparation of two-dimensional nitride materials by a biological template method combining vacuum nitriding with enhanced photocatalytic performance. Two-dimensional mesoporous Ta 3 N 5 is synthesized by a simple sol-gel process with filter paper as a biological template and vacuum nitriding reaction, leading to an efficient photocatalytic performance. [Display omitted] • Two-dimensional mesoporous Ta 3 N 5 was prepared by a biological template. • The prepared Ta 3 N 5 shows a wide light response range up to the near infrared region. • The special two-dimensional structure shortens the charge transfer distance. • The Ta 3 N 5 photocatalyst shows a superior hydrogen production performance. [ABSTRACT FROM AUTHOR]

Supercritical water gasification (SCWG) of coal is a promising clean coal technology, which discards the traditional coal combustion and oxidation reaction to release carbon dioxide and other pollutants and replaces coal with a gasification reduction reaction in supercritical water to finally convert coal into a hydrogen-rich gas product with no net carbon dioxide emissions and no pollutant emissions, and thus has received much attention in recent years. However, the experimental conditions of coal to the hydrogen reactor are harsh, costly, and not easy to visualize and analyze, so numerical calculation and simulation analysis are important for the design, optimization, and industrial scaling-up of the reactor. In order to study the effect of the temperature field on the hydrogen production rate of the coal supercritical water gasification hydrogen production reactor, a numerical simulation calculation model is developed for this reactor in this paper. Comparing the experimental data in the literature, the maximum relative error of the gasification product yield per kg of coal between the two is less than 5%, which verifies the accuracy of the model built and the numerical method adopted in this paper. On this basis, the effects of supercritical water temperature and coal slurry temperature on the reactor's gasification products and reaction rate were investigated in depth. The results show that increasing the supercritical water temperature is beneficial to improve the reactor hydrogen production efficiency, while the high coal slurry temperature is not conducive to adequate reaction, thus reducing the hydrogen production efficiency. For the laboratory coal supercritical water gasification to hydrogen reactor studied in this paper, the ideal temperature of supercritical water is 850~900 K, and the ideal temperature of coal slurry is 400–450 K. The conclusions of this paper can provide some reference for subsequent industrial scale-up studies of the reactor. [ABSTRACT FROM AUTHOR]

As an example of principally different type of catalytic support in the paper by Suboch and Podyacheva [[11]], bamboo-like nitrogen-doped carbon nanotubes (N-CNTs) were used to synthesize supported palladium catalysts (0.2-2 wt.%) for hydrogen production via gas phase formic acid decomposition. Similarly, high activity and stability were demonstrated in the formic acid decomposition by a single-atom Ni catalyst supported on N-doped porous carbon with active Ni-N SB 4 sb sites [[2]]. To solve problems related to global warming, environmental pollution, and green energy fields, a lot of research is now devoted to the catalysis of biofuels and biogas transformation into syngas and hydrogen. [Extracted from the article]

Copper-based catalysts are widely used in methanol steam reforming to produce hydrogen. In this paper, the supportive effect of the crystal phase of ZrO2 on Cu-based catalysts in methanol steam reforming is discussed. Monoclinic(m-), Tetragonal(t-) and mixed ZrO2 phases were prepared, and structure–activity relationships were investigated with XRD, H2-TPR, BET, HR-TEM and XPS. It was found that the catalyst with a 81.4% monoclinic ZrO2 crystal phase exhibited the highest methanol conversion (88.5%) and the highest hydrogen production rate (104.6 μmol/gcat·s) at 275 °C as it displayed the best reducing properties and more oxygen vacancies on the catalyst surface. Oxygen vacancies can produce more Cu1+ + Cu0, which is the active species for methanol steam reforming on the catalyst surface, and therefore affect catalytic activity. [ABSTRACT FROM AUTHOR]

Owing to the massive expansion and intermittent nature of renewable power, green hydrogen production, storage, and transportation technologies with improved economic returns need to be developed. Moreover, the slowness of the dehydrogenation reaction is a primary barrier to the commercialization of liquid organic hydrogen carrier (LOHC) technology. The present study focused on increasing the speed of dehydrogenation, resulting in the proposal of a triple-loop dehydrogenation system comprising reaction, heating, and chilling loops. The reactor has a rotating cage containing a packed bed of catalyst pellets, which is designed to enhance both heat and mass transfer by helping to detach precipitated hydrogen bubbles from the catalyst surface. In addition, the centrifugal force aids in isolating the gas phase from the LOHC liquid. A dehydrogenation experiment was conducted using the reaction and chilling loops, which revealed that the average hydrogen production rate during the first hour was 52.6 LPM (liter per minute) from 26.3 L of perhydro-dibenzyl-toluene with 1.5 kg of 0.5 wt% Pt/Al2O3 catalyst. This was approximately 48% more than the value predicted with the reaction kinetics measured with a small-scale plug flow dehydrogenation reactor with less than 1.0 g of 5.0 wt% Pt/Al2O3 catalyst. The concept, construction methods, and results of the preliminary gas infiltration, flow visualization, and reactor pumping experiments are also described in this paper. [ABSTRACT FROM AUTHOR]

With the current trends of wind energy already playing a major part in the Scottish energy supply, the capacity of wind farms is predicted to grow exponentially and reach further depths offshore. However, a key challenge that presents itself is the integration of large producing assets into the current UK grid. One potential solution to this is green hydrogen production, which is being heavily researched in industry, with many concepts being investigated for large-scale purposes. However, the operations and maintenance (O&M) costs and availability of green hydrogen systems need to be quantified to ensure economical and technical viability, which is sparse in the available literature. The study presented in this paper investigated the availability and O&M costs of coupled wind–hydrogen systems by attempting to quantify the failure rates, repair times, repair costs and number of technicians required for key green hydrogen components. This study also utilised an O&M model created by the University of Strathclyde, which uses Monte Carlo Markov chain simulations to produce the O&M outputs. A number of assumptions were made throughout the study in relation to the O&M model inputs, and the baseline availability for the coupled wind–hydrogen system was 85.24%. Whilst the wind turbine still contributed a major part to the downtime seen in the simulations, the combined hydrogen system also contributed a significant amount, a total of 37%, which could have been due to the technology readiness levels of some the components included in the hydrogen system. [ABSTRACT FROM AUTHOR]

In this paper, the reported MOF ([Co(bimip)(H2O)0.5]·0.5H2O) was employed in photocatalytic CO2 reduction, antibacterial, and dye adsorption experiments. The photocatalytic activity of the MOF for CO2 reduction was systematically investigated. The high average CO generation rate of 3421.59 μmol·g−1·h−1 after 12 h confirms the efficient photocatalytic CO2 reduction ability of the MOF. At the same time, the MOF can completely inhibit the growth of S. aureus and C. albicans within 24 h when its concentration reaches 400 μg/mL and 500 μg/mL, respectively. The MOF has an adsorption capacity for CR. The adsorption rate was 83.42% at 60 min, and the adsorption capacity of the MOF for CR reached 500.00 mg·g−1. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of hydrogen generation from hydrocarbon gases using Steam Methane Reforming (SMR) with byproduct CO2 injected into and stored in a partially depleted oil reservoir. It focuses on the reservoir aspects of the problem using numerical simulation of the processes. To this aim, a numerical model of a real oil reservoir was constructed and calibrated based on its 30-year production history. An algorithm was developed to quantify the CO2 amount from the SMR process as well as from the produced fluids, and optionally, from external sources. Multiple simulation forecasts were performed for oil and gas production from the reservoir, hydrogen generation, and concomitant injection of the byproduct CO2 back to the same reservoir. EOR from miscible oil displacement was found to occur in the reservoir. Various scenarios of the forecasts confirmed the effectiveness of the adopted strategy for the same source of hydrocarbons and CO2 sink. Detailed simulation results are discussed, and both the advantages and drawbacks of the proposed approach for blue hydrogen generation are concluded. In particular, the question of reservoir fluid balance was emphasized, and its consequences were presented. The presented technology, using CO2 from hydrogen production and other sources to increase oil production, also has a significant impact on the protection of the natural environment via the elimination of CO2 emission to the atmosphere with concomitant production of H2. [ABSTRACT FROM AUTHOR]

Green hydrogen, produced by water electrolysis with renewable energy, plays a crucial role in the revolution towards energy sustainability, and it is considered a key source of clean energy and efficient storage. Its ability to address the intermittency of renewable sources and its potential to decarbonize sectors that are difficult to electrify make it a strategic component in climate change mitigation. By using a method based on a bibliometric review of scientific publications, this paper represents a significant contribution to the emerging field of research on green hydrogen and provides a detailed review of electrolyzer technologies, identifying key areas for future research and technology development. The results reflect the immaturity of a technology which advances with different technical advancements, waiting to find the optimal technical solution that allows for its massive implementation as a source of green hydrogen generation. According to the results found in this article, alkaline (ALK) and proton exchange membrane (PEM) electrolyzers seem to be the ones that interest the scientific community the most. Similarly, in terms of regional analysis, Europe is clearly committed to green hydrogen, in view of the analysis of its scientific results on materials and electrolyzer capacity forecasts for 2030. [ABSTRACT FROM AUTHOR]

In recent times, renewable energy systems (RESs) such as Photovoltaic (PV) and wind turbine (WT) are being employed to produce hydrogen. This paper aims to compare the efficiency and performance of PV and WT as sources of RESs to power polymer electrolyte membrane electrolyzer (PEMEL) under different conditions. The study assessed the input/output power of PV and WT, the efficiency of the MPPT controller, the calculation of the green hydrogen production rate, and the efficiency of each system separately. The study analyzed variable irradiance from 600 to 1000 W/m2 for a PV system and a fixed temperature of 25°C, while for the WT system, it considered variable wind speed from 10 to 14 m/s and zero fixed pitch angle. The study demonstrated that the applied controllers were effective, fast, low computational, and highly accurate. The obtained results showed that WT produces twice the PEMEL capacity, while the PV system is designed to be equal to the PEMEL capacity. The study serves as a reference for designing PV or WT to feed an electrolyzer. The MATLAB program validated the proposed configurations with their control schemes. [ABSTRACT FROM AUTHOR]

Nowadays, one of the most important areas in refining the energy sector in the developed countries is the transition to environmentally friendly technologies, and hydrogen energy production is the most promising of them. In this rapidly advancing area, significant progress in creating new technologies for hydrogen fuel generation, transportation, storage, and consumption has been recently observed, while a fast-growing number of research papers and implemented commercial projects related to hydrogen makes it necessary to give their general review. In particular, the combination of the latest achievements in this area is of particular interest with a view to analyzing the possibility of creating hydrogen fuel supply chains. This paper presents an analytical review of existing methods of hydrogen production, storage, and transportation, including their key economic and energy-related characteristics, and proposes an approach to the creation, analysis, and optimization of hydrogen supply chains. A mathematical model has been developed to determine the cost of hydrogen, taking into account the supply chain, including production, transport and storage. Based on the results of modeling in the given scenario conditions for 2030, 2040 and 2050, promising hydrogen supply chains have been established. Under the various scenario conditions, hydrogen production by 2050 is most preferable by the method of steam conversion of methane with a cost of 8.85 USD/kg H2. However, due to the environmental effect, electrolysis also remains a promising technology with a cost of hydrogen produced of 17.84 USD/kg. [ABSTRACT FROM AUTHOR]

This paper presents a systematic and comprehensive mathematical model for alkaline water electrolyzer cells, which can be used for simulation and analysis. The model accounts for factors such as gas evolution reactions, dissolution of gases in the electrolyte, bubble formation, and charge transport. It is based on a numerical two-phase model using the Euler-Euler approach, which has been validated against experimental data for various current densities. The study compares the impact of varying potassium hydroxide (KOH) concentration, separator porosity, and electrolyte flow rates on two-phase flow and bubble coverage. Therefore, the electrolyte in the cell consists of a solution of potassium hydroxide in water. The formation of gas bubbles at the electrodes decreases the electrolyte's ionic conductivity. Additionally, the presence of these bubbles on the electrode surfaces reduces the available surface area for electrochemical reactions, leading to an increase in the overpotential at a given current density. Furthermore, this paper demonstrates how a neural network and ensembled tree model can predict hydrogen production rates in an alkaline water electrolysis process. The trained neural network accurately predicted the hydrogen production rates, indicating the potential of using neural networks for optimization and control of alkaline water electrolysis processes. The model has an average R-squared value of 0.98, indicating a good fit to the data. A new method of describing bubble transfer, "bubble diffusion," is introduced to improve performance and reduce costs. The model is solved using COMSOL Multi physics 6.0. The machine learning models in this study were built, trained, and tested using MATLAB software R2020a. [ABSTRACT FROM AUTHOR]

Purpose: Elaboration of an indicator to include the dynamic aspect of citations in bibliometric indexes. Design/methodology/approach: A new bibliometric methodology—the f2-index—is applied at the career level and at the level of the recent 5 years to analyze the dynamic aspect of bibliometrics. The method is applied, as an illustration, to the field of corporate governance. Findings: The compound F2-index as an extension of the f2-index recognizes past achievements but also values new research work with potential. The method is extended to the h-index and the h2-index. An activity index is defined as the ratio between the recent h'-index to the career h-index. Research limitations: The compound F2 and H-indexes are PAC, probably approximately correct, and depend on the selection and database. Practical implications: The F2- and H compound indexes allow identifying the rising stars of a field from a dynamic perspective. The activity ratio highlights the contribution of younger researchers. Originality/value: The new methodology demonstrates the underestimated dynamic capacity of bibliometric research. [ABSTRACT FROM AUTHOR]

An alternative solution to the problem of aluminum–plastic multilayer waste utilization was suggested. The process can be used for hydrogen generation and layer separation. Three different sorts of aluminum–plastic sandwich materials were treated with an alkali solution. In the temperature range of 50–70 °C, for tablet blisters of polyvinylchloride and aluminum (14.8 wt.%), the latter thoroughly reacted in 15–30 min. For sheets of paper, polyethylene, and aluminum (20 wt.%), full hydrogen 'recovery' from reacted aluminum component took 3–8 min. From the lids of polyethylene terephthalate, aluminum (60 wt.%), and painted polyethylene with perforations, the aluminum was consumed after 45–105 min. The effect of perforations was the reduction of the process duration from nearly 90 min for the lids with no perforations to nearly 45 min for the perforated ones (at 70 °C). Perforations provided better contact between the aluminum foil, isolated between the plastic layers, and the alkali solution. Hydrogen bubbles originating near those perforations provided foil separation from the upper painted plastic layer by creating gas gaps between them. The remaining components of the composite multilayer materials were separated and ready for further recycling. [ABSTRACT FROM AUTHOR]

The photocatalytic hydrolysis reaction primarily unfolds on the material's surface, making the material's morphology and microstructure critical for the catalytic efficiency of photocatalysts. In this paper, a formic acid-assisted melamine hydrothermal self-assembly method is explored to prepare g-C 3 N 4 photocatalysts with a unique morphology. The impact of sintering temperature on the morphology of the g-C 3 N 4 photocatalysts are explored and the effect of formic acid concentration on the XRD and FTIR was analyzed. Findings reveal that the g-C 3 N 4 nanostructures photocatalyst possesses fibrous tubular and nanosheet structures, boasting a heightened specific surface area (32.9 m2/g) and a more refined graphite-like crystalline framework. When synthesized with a 0.15 M concentration of formic acid, the g- C 3 N 4 nanostructured photocatalyst achieved a hydrogen production rate (1289.4 μmol h−1 g−1), which is approximately 4.8 times greater than that of bulk g-C 3 N 4 (264.7 μmol h−1 g−1). This work provides a simple method for preparing high-performance g-C 3 N 4 based photocatalysts for visible light hydrolysis hydrogen production. [ABSTRACT FROM AUTHOR]

In this paper, a Fe 2 O 3 /g-C 3 N 4 nanocomposite was prepared using a facile precipitation method, demonstrating the influence of g-C 3 N 4 nanosheets on the photocatalytic efficiency of α-Fe 2 O 3. Despite the stability of pure g-C 3 N 4 during heat treatment up to 700 °C, its presence, along with iron oxide during calcination, reduces its stability temperature to about 450 °C. The reduction of hematite to magnetite by carbon is accompanied by the decomposition of g-C 3 N 4. The appropriate calcination temperature determined for this synthesis process is 390 °C. Microscopic analysis revealed a uniform distribution of α-Fe 2 O 3 particles (average particle size of 16 nm) on g-C 3 N 4 nanosheets with a close and intimate contact. The g-C 3 N 4 content in the nanocomposite influenced the size of Fe 2 O 3 nanoparticles. g-C 3 N 4 nanosheets in the α-Fe 2 O 3 structure changed the band gap from 1.9 to 2.4 eV, reducing the recombination rate of electrons and holes. A nanocomposite containing 10 wt% g-C 3 N 4 showed the highest photocatalytic performance. The Z-scheme charge transfer mechanism and the significant role of superoxide radicals in the photocatalytic process were identified. The nanocomposite's photocatalytic efficiency was evaluated on various pollutants, including methylene blue (MB, 88 %), phenol (60 %), methyl orange (MO, 38 %), and the pharmaceutical compound Metformin (96 %). The α-Fe 2 O 3 /10 wt% g-C 3 N 4 nanocomposite exhibited the highest hydrogen production rate at 435 μmol/g.h, establishing its importance in photocatalytic performance. [ABSTRACT FROM AUTHOR]

The demand for susceptible and selective hydrogen gas sensors is growing in fuel cells, chemical production, and automotive industries. Detecting H 2 gas at the ppm or ppb level is crucial due to its colourless, odourless, tasteless nature, as well as its flammability and explosiveness. Transition metal dichalcogenides (TMDs) and metal oxide (MO) semiconductors-based hybrid structures have garnered attention in recent years as promising candidates for gas sensing applications owing to their unique properties, including a high surface area, tunable bandgap, and strong gas adsorption. This paper aims to offer insights into the potential of TMD-MO hybrid structures as the next generation of hydrogen gas sensing platforms, contributing to developing highly sensitive and selective gas sensors for diverse industrial applications. TMD-MO hybrid structures are vital for detecting hydrogen gas with high sensitivity and selectivity, which are essential for safe and efficient hydrogen-based systems. Furthermore, these hybrid structures hold significant potential for further customization and enhancement to suit specific applications. Overall, TMD-MO hybrid structures offer a promising avenue for developing next-generation hydrogen gas sensors useable in various industrial applications and promoting a safe and sustainable hydrogen economy. [ABSTRACT FROM AUTHOR]

In this paper, the generation of hydrogen from alkaline sodium borohydride solution by hydrolysis is studied. To obtain catalysts for efficient hydrogen generation, Ni, Mn, Mo, and Co metals were deposited on the Cu surface by the simple electroless metal deposition method using morpholine borane as a reducing agent. Depending on the peculiarities of the deposition of each metal, the coating thickness was ca. 1 μm for all catalysts. The deposited coatings were compact and crack-free, with multilayer characteristics and a cauliflower-like structure. The prepared Ni/Cu, NiMn/Cu, NiMo/Cu, NiCo/Cu, NiCoMn/Cu, NiCoMo/Cu, and NiCoMoMn/Cu catalysts showed an efficient catalytic activity for sodium borohydride hydrolysis reaction. The lowest activation energy of 45.3 kJ mol−1 for sodium borohydride hydrolysis reaction was obtained using the NiCoMoMn/Cu catalyst. The highest hydrogen generation rate of 3.08 mL min−1 was also achieved using this catalyst at 303 K. With a further increase in temperature to 343 K, the hydrogen generation rate catalyzed by the NiCoMoMn/Cu increased 7.7 times and reached 23.57 mL min−1. [ABSTRACT FROM AUTHOR]

This paper proposes a Swiss-roll-type mini-reformer employing a copper–zinc catalyst for high-efficient SRM process. Although the commercially available copper–zinc catalysts commonly used in cylindrical-type reformers provide decent conversion rates in the short term, their long-term durability still requires improvement, mainly due to temperature variations in the reformer, catalyst loading, and thermal sintering issues. This Swiss-roll-shaped mini-reformer is designed to improve thermal energy preservation/temperature uniformity by using dual spiral channels to improve the long-term durability while maintaining methanol-reforming efficiency. It was fabricated on a copper plate that was 80 mm wide, 80 mm long, and 4 mm high with spiral channels that were 2 mm deep, 4 mm wide, and 350 mm long. To optimize the design and reformer operation, the catalyst porosity, gas hourly speed velocity (GHSV), operation temperature, and fuel feeding rate are investigated. Swiss-roll-type reformers may require higher driving pressures but can provide better thermal energy preservation and temperature uniformity, posing a higher conversion rate for the same amount of catalyst when compared with other geometries. By carefully adjusting the catalyst bed porosity, locations, and catalyst loading amount as well as other conditions, an optimized gas hourly space velocity (GHSV) can be obtained (14,580 mL/g·h) and lead to not only a high conversion rate (96%) and low carbon monoxide generation rate (0.98%) but also a better long-term durability (decay from 96% to 88.12% after 60 h operation time) for SRM processes. The decay rate, 0.13%/h, after 60 h of operation, is five-folds lower than that (0.67%/h, 0.134%/h) of a commercial cylindrical-type fixed-bed reactor with a commercial catalyst. [ABSTRACT FROM AUTHOR]

Aiming to meet the low-carbon demands of power generation in the process of carbon peaking and carbon neutralization, this paper proposes an optimal PV-hydrogen zero carbon emission microgrid. The light–electricity–hydrogen coupling utilization mode is adopted. The hydrogen-based energy system replaces the carbon-based energy system to realize zero carbon emissions. Firstly, the mathematical models of photovoltaic, hydrogen and electric energy storage systems in a microgrid are built. Then, the optimal allocation model of the microgrid source storage capacity is established, and a scheduling strategy considering the minimum operational cost of energy storage equipment is proposed. The priority of equipment output is determined by comparing the operational costs of the hydrogen energy storage system and the electric energy storage system. Finally, the proposed scheme is compared with the scheduling scheme of the battery priority and the hydrogen energy system priority in an actual microgrid. It is verified that the scheme can ensure stable power-generating, zero carbon operation of a microgrid system while reducing the total annual power costs by 9.8% and 25.1%, respectively. [ABSTRACT FROM AUTHOR]

Hydrogen refueling stations (HRSs) are critical for the popularity of hydrogen vehicles (fuel cell electric vehicles—FCEVs). However, due to high installation investment and operating costs, the proliferation of HRSs is difficult. This paper studies HRSs with on-site electrolytic production and hydrogen storage devices and proposes an optimization method to minimize the total costs including both installation investment and operating costs (OPT-ISL method). Moreover, to acquire the optimization constraints of hydrogen demand, this paper creatively develops a refueling behavior simulation method for different kinds of FCEVs and proposes a hydrogen-demand estimation model to forecast the demand with hourly intervals for HRS. The Jensen–Shannon divergence is applied to verify the accuracy of the hydrogen-demand estimation. The result: 0.029 is much smaller than that of the estimation method in reference. Based on the estimation results and peak-valley prices of electricity from the grid, a daily hydrogen generation plan is obtained, as well as the optimal capacities of electrolyzers and storage devices. As for the whole costs, compared with previous configuration methods that only consider investment costs or operating costs, the proposed OPT-ISL method has the least, 8.1 and 10.5% less, respectively. Moreover, the proposed OPT-ISL method shortens the break-even time for HRS from 11.1 years to 7.8 years, a decrease of 29.7%, so that the HRS could recover its costs in less time. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) materials, renowned for their high specific surface area, excellent conductivity, and customizable functional groups, are widely employed as catalyst carriers. However, enhancing the activity of Ru-based catalysts supported on AC (Ru/AC) for ammonia decomposition remains a challenge. In this study, commercial AC was utilized as a substrate, with glucose and urea employed as modifiers. Specifically, the surface of the AC was modified via a hydrothermal pyrolysis method, resulting in the successful post-treatment in situ co-doping of nitrogen (ACGN). Experimental results revealed that Ru/AC-GN exhibited a hydrogen production rate 46% higher than that of Ru/AC at 475 °C, indicating improved activity and stability. The characterization of AC-GN demonstrated that nitrogen doping primarily occurred on the external surface and macropores of the AC, increasing the nitrogen content in the carrier, particularly pyrrolic nitrogen content, while preserving the original structural and morphological integrity of the AC. The enhanced dispersion of Ru, combined with the improved electronic transmission capabilities and strengthened interactions between the metal and the modified carrier, were identified as pivotal factors contributing to the enhanced lowtemperature efficacy of Ru/AC-GN. This paper presents a novel direction for the large-scale preparation of efficient catalysts for ammonia decomposition. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries as one of the most promising technologies for energy storage applications have been attracting increasing attentions. A crucial challenge for the commercialization of lithium–sulfur batteries is the poor stability of lithium sulfide against moisture, which may lead to the release of toxic hydrogen sulfide gas. However, the risk of hydrogen sulfide releasing from lithium–sulfur batteries under the limiting conditions is still unclear. In this paper, we herein investigate the mechanism of hydrogen sulfide releasing in lithium–sulfur batteries, and evaluate the effect of battery discharging on the generation of hydrogen sulfide. The production of sulfion and hydrogen sulfide is qualitatively/qualitatively studied. According to above results, the behavior of hydrogen sulfide formation in the batteries is elucidated based on thermodynamic simulation. Furthermore, the effect of discharging of lithium–sulfur batteries on the hydrogen sulfide releasing is qualitatively calculated. These results show that the hydrogen sulfide is indeed produced from the discharging products of lithium–sulfur battery under the acid condition, the findings can also provide some guidelines or suggestions for the practical applications of lithium–sulfur battery. [ABSTRACT FROM AUTHOR]

Generally, a stand-alone flash-binary geothermal power plant loses most of its input energy, so its efficiency declines accordingly. Its overall ability can be augmentable by utilizing structural modification and waste heat recovery leading to the most suitable exergetic performance with lower costs. On this account, the current paper suggests and investigates an innovative waste heat recovery for a dual-flash binary geothermal power plant. The integrated process consists of a Rankine cycle, a reverse osmosis desalination, and a proton exchange membrane electrolyzer. Here, two main processes, i.e., waste heat-to-power and power-to-hydrogen/freshwater, are regarded. Accordingly, the applicability of the system is examined from the energy, exergy, and economic points of view. Thus, a relevant sensitivity analysis is applied to the response variables where the effect of separator 2 pressure is more significant than other parameters. In addition, a non-dominated sorting genetic algorithm-II (NSGA-II) method is implemented to optimize the system thermodynamically and economically. The optimum state reveals an exergy efficiency of 43.83% and a levelized cost of products of 4.54 $/MWh. In this situation, the net output power and production rate of freshwater and hydrogen are estimated at 6474 kW, 22.51 kg/s, and 1.84 kg/h, respectively. Graphical representation of the novel devised renewable energy-fueled trigeneration setup [ABSTRACT FROM AUTHOR]

Hydrogen energy is expected to become one of the most efficient ways to decarbonize global energy and transportation systems. Green hydrogen production costs are currently high but are likely to decline due to the economy of scale and learning-by-doing effects. The purpose of this paper is to forecast future green hydrogen costs based on the multicomponent learning curves approach. The study investigates the learning curves for the main components in hydrogen value chains: electrolyzers and renewable energy. Our findings estimate the learning rates in the production of PEM and AE electrolyzers as 4%, which is quite conservative compared to other studies. The estimations of learning rates in renewable energy electricity generation range from 14.28 to 14.44% for solar-based and 7.35 to 9.63% for wind-based production. The estimation of the learning rate in green hydrogen production ranges from 4% to 10.2% due to uncertainty in data about the cost structure. The study finds that government support is needed to accelerate electrolysis technology development and achieve decarbonization goals by 2050. [ABSTRACT FROM AUTHOR]

The continued use of energy sources based on fossil fuels has various repercussions for the environment. These repercussions are being minimized through the use of renewable energy supplies and new techniques to decarbonize the global energy matrix. For many years, hydrogen has been one of the most used gases in all kinds of industry, and now it is possible to produce it efficiently, on a large scale, and in a non-polluting way. This gas is mainly used in the chemical industry and in the oil refining industry, but the constant growth of its applications has generated the interest of all the countries of the world. Its use in transportation, petrochemical industries, heating equipment, etc., will result in a decrease in the production of greenhouse gases, which are harmful to the environment. This means hydrogen is widely used and needed by countries, creating great opportunities for hydrogen export business. This paper details concepts about the production of green hydrogen, its associated technologies, and demand projections. In addition, the current situation of several countries regarding the use of this new fuel, their national strategy, and advances in research carried out in different parts of the world for various hydrogen generation projects are discussed. Additionally, the great opportunities that Chile has for this new hydrogen export business, thanks to the renewable energy production capacities in the north and south of the country, are discussed. The latter is key for countries that require large amounts of hydrogen to meet the demand from various industrial, energy, and transportation sectors. Therefore, it is of global importance to determine the real capacities that this country has in the face of this new green fuel. For this, modeling was carried out through mathematical representations, showing the behavior of the technologies involved in the production of hydrogen for a system composed of an on-grid photovoltaic plant, an electrolyser, and compressor, together with a storage system. The program optimized the capacities of the equipment in such a way as to reduce the costs of hydrogen production and thereby demonstrate Chile's capacity for the production of this fuel. From this, it was found that the LCOH for the case study was equivalent to 3.5 USD/kg, which is not yet considered a profitable value for the long term. Due to this, five case studies were analyzed, to see what factors influence the LCOH, and thereby reduce it as much as possible. [ABSTRACT FROM AUTHOR]

Fe-based chemical looping gasification is a clean biomass technology, which has the advantage of reducing CO2 emissions and the potential of self-sustaining operation without supplemental heating. A novel process combining Fe-based chemical looping and biomass pyrolysis was proposed and simulated using Aspen Plus. The biomass was first subjected to pyrolysis to coproduce biochar, bio-oil and pyrolysis gas; the pyrolysis gas was subjected to an Fe looping process to obtain high-purity hydrogen and carbon dioxide. The influences of the pyrolysis reactor operating temperature and fuel reactor operation temperature, and the steam reactor and air reactor on the process performance are researched. The results showed that, under the operating condition of the established process, 23.07 kg/h of bio-oil, 24.18 kg/h of biochar, 3.35 kg/h of hydrogen and a net electricity of 3 kW can be generated from 100 kg/h of rice straw, and the outlet CO2 concentration of the fuel reactor was as high as 80%. Moreover, the whole exergy efficiency and total exergy loss of the proposed process was 58.98% and 221 kW, respectively. Additionally, compared to biomass direct chemical looping hydrogen generation technology, the new process in this paper, using biomass pyrolysis gas as a reactant in the chemical looping hydrogen generation process, can enhance the efficiency of hydrogen generation. [ABSTRACT FROM AUTHOR]

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This paper proposes a self-sustaining control model for proton-exchange membrane (PEM) electrolysis devices, aiming to maintain the temperature of their internal operating environment and, thus, improve the electrolysis efficiency and hydrogen production rate. Based on the analysis of energy–substance balance and electrochemical reaction characteristics, an electrothermal-coupling dynamic model for PEM electrolysis devices was constructed. Considering the influence of the input energy–substance and the output hydrogen and oxygen of PEM electrolysis devices on the whole dynamic equilibrium process, the required electrical energy and water molar flow rate are dynamically adjusted so that the temperature of the cathode and the anode is maintained near 338.15 K. The analytical results show that the hydrogen production rate and electrolysis efficiency are increased by 0.275 mol/min and 3.9%, respectively, by linearly stacking 100 PEM electrolysis devices to form a hydrogen production system with constant cathode and anode operating temperatures around 338.15 K in the self-sustaining controlled mode. [ABSTRACT FROM AUTHOR]

Photoreforming (PR) of biomass can be considered a viable technology under mild experimental conditions to produce hydrogen with a high reaction rate using compounds from renewable resources and waste materials. The application of biomass PR gives rise to both hydrogen generation and biomass waste valorization. The process could be scaled up to obtain hydrogen under natural sunlight irradiation, and research on polymeric carbon nitride (g-C3N4)-based photocatalysts has been widely carried out in recent years. The non-metallic-based carbon nitride materials are economical and (photo)stable polymer semiconductors, and their physicochemical surface and electronic properties are optimal for obtaining H2, which can be considered a gas that does not cause major environmental problems. Some hindrances related to their structure, such as the low absorption of visible light and the relatively high recombination rate of electron-hole pairs, restrict the performance; therefore, it is necessary to improve their activity and the yield of the reaction by modifying them in various ways. Various types of solutions have been proposed in this regard, such as, for example, their coupling with other semiconductors to form composite materials. The current mini-review aims to overview the PR field, reporting some of the most interesting papers devoted to understanding the role of g-C3N4 in biomass PR. Information on many physico-chemical aspects related to the performance of the process and possible ways to obtain better results than those present up to now in the literature will be reported. [ABSTRACT FROM AUTHOR]

In this paper, a new Newton-based extremum-seeking control for dynamic systems is proposed using Kalman filter for gradient and Hessian estimation as well as a stochastic perturbation signal with time-varying amplitude. The obtained Kalman filter based Newton extremum-seeking control (KFNESC) makes it possible to accelerate the convergence to the extremum and attenuate the steady-state oscillations. The convergence and oscillation attenuation properties of the closed-loop system with KFNESC are considered, and the proposed control is applied to a two-stages anaerobic digestion process in order to maximize the hydrogen production rate, which has better robustness and a slower steady-state oscillation with the comparison of Newton-based ESC and sliding mode ESC. [ABSTRACT FROM AUTHOR]

In this paper, the results of an experimental study on hydrogen production at a tungsten discharge electrode with negative polarity in the DC electrolysis of a typical 10 wt% Na2CO3 aqueous solution in three operational regimes (the Faradaic, transition, and plasma-driven solution electrolysis (PDSE)) are presented for the first time. To focus the study on hydrogen production, a flowing inert gas (argon) was used to transport the gas mixture produced at the discharge electrode and prevent any other potential chemical reactions. The results showed that the highest hydrogen production rate of 0.147 g(H2)/h was achieved in the cathodic PDSE regime at the applied DC voltage of 198 V. However, the energy yield of hydrogen production of 0.405 g(H2)/kWh obtained at the applied voltage range of 141–170 V in the PDSE regime was lower than that obtained in the Faradaic regime (0.867 g(H2)/kWh) at 28 V. The energy balance of hydrogen production in the cathodic PDSE regime for the typical aqueous solution of Na2CO3 carried out for the first time showed that a significant share (˃98%) of the electrical energy consumed is spent on heating and evaporation of the electrolytic solution. This explains why the energy yield of hydrogen production is low in the PDSE regime. Because most of the energy is consumed for heat generation in the cathodic PDSE regime, organic liquid hydrogen carriers, such as alcohols, which have a lower boiling temperature, heat of evaporation, and standard Gibbs free energy, should be considered better aqueous electrolytic solutions in terms of the energy yield of hydrogen production in the PDSE regime. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the results of a hybrid air independent propulsion based on fuel cells for small submarines. The weight and volume of the investigated propulsion, and the major tactical and technical characteristics of the 540-tonne submarine equipped with this propulsion have been determined. Five onboard systems for the hydrogen storage or generation, and the oxygen storage are considered. Combining a micro-balloon hydrogen system with the cryogenic oxygen storage is the best solution for the propulsion. The submerged endurance and range improved 32.1-64.8 times, as compared to just battery. The indiscretion ratio equals zero at cruising speeds of less than 7.1 knots, while at higher speeds, this value has dramatically decreased, and submarine secrecy has increased significantly. [ABSTRACT FROM AUTHOR]

Green hydrogen is becoming an increasingly important energy supply source worldwide. The great potential for the use of hydrogen as a sustainable energy source makes it an attractive energy carrier. In this paper, we discuss the potential of producing green hydrogen in Jordan. Aqaba, located in the south of Jordan, was selected to study the potential for producing green hydrogen, due to its proximity to a water source (i.e., the Red Sea). Two models were created for two electrolyzer types using MATLAB. The investigated electrolyzers were alkaline water (ALK) and polymeric electrolyte membrane (PEM) electrolyzers. The first model was used to compare the required capacity of the PV solar system using ALK and PEM from 2022 to 2025, depending on the learning curves for the development of these technologies. In addition, this model was used to predict the total investment costs for the investigated electrolyzers. Then, a techno-economic model was constructed to predict the feasibility of using this technology, by comparing the use of a PV system and grid electricity as sources for the production of hydrogen. The net present value (NPV) and levelized cost of hydrogen (LCOH) were used as indicators for both models. The environmental effect, according to the reduction of CO2 emissions, was also taken into account. The annual production of hydrogen was 70.956 million kg. The rate of hydrogen production was 19.3 kg/s and 1783 kg/s for ALK and PEM electrolyzers, respectively. The LCOH was 4.42 USD/kg and 3.13 USD/kg when applying electricity from the grid and generated by the PV system, respectively. The payback period to cover the capital cost of the PV system was 11 years of the project life, with a NPV of USD 441.95 million. Moreover, CO2 emissions can be reduced by 3042 tons/year by using the PV as a generation source, instead of fossil fuels to generate electricity. The annual savings, with respect to the reduction of CO2 emissions, was USD 120,135. [ABSTRACT FROM AUTHOR]

CoH SB x sb PO SB y sb nanoparticles exhibit a better hydrogen evolution reaction improvement effect on the CdIn SB 2 sb S SB 4 sb photocatalyst than Pt nanoparticles. These eleven papers were devoted to achieving high-efficiency photocatalysts by broadening the light absorption range, inhibiting the photo-induced electrons and holes recombination, and promoting the extraction of photo-induced charges for chemical reactions. The CoH SB x sb PO SB y sb accelerates the hole transfer and inhibits the electron and hole recombination, thus promoting the photocatalytic hydrogen evolution reaction activity under visible light. [Extracted from the article]

Due to there is no better way to exploit depleted gas reservoirs, and hydrogen can generate from natural gas combustion. In this paper, the possibility of in-situ hydrogen generation in air injected gas reservoirs was determined through pseudo dynamic experiments. The study indicated that higher temperature and steam/methane ratio can generate more hydrogen, and the temperature should not be lower than 600 °C within gas reservoirs. The debris has positive catalysis for hydrogen generation. The maximum mole fraction of hydrogen was 26.63% at 600 °C. [ABSTRACT FROM AUTHOR]

A potential method of storing and transporting hydrogen safely in a cost-effective and practical way involves the utilization of molecules that contain hydrogen in their structure such as ammonia. Because of its high hydrogen content and carbon-free molecular structure, as well as the maturity of related technology (easy liquefaction), ammonia has gained attention as a "hydrogen carrier" for the generation of energy. Unfortunately, hydrogen production from ammonia requires an efficient catalyst to achieve high conversion at low reaction temperatures. Recently, very attractive results have been obtained with low-surface-area materials. This review paper is focused on summarizing and comparing recent advances in novel, economic and active catalysts for this reaction, paying particular attention to materials with low surface area such as silicon carbide (SiC) and perovskites (ABO3 structure). The effects of the supports, the active phase and the addition of promoters in such low-porosity materials have been analyzed in detail. Advances in adequate catalytic systems (including support and active metal) benefit the perspective of ammonia as a hydrogen carrier for the decarbonization of the energy sector and accelerate the "hydrogen economy". [ABSTRACT FROM AUTHOR]

This paper reviews the progress in applying the plasma-driven solution electrolysis (PDSE), which is also referred to as the contact glow-discharge electrolysis (CGDE) or plasma electrolysis, for hydrogen production. The physicochemical processes responsible for the formation of PDSE and effects occurring at the discharge electrode in the cathodic and anodic regimes of the PDSE operation are described. The influence of the PDSE process parameters, especially the discharge polarity, magnitude of the applied voltage, type and concentration of the typical electrolytic solutions (K2CO3, Na2CO3, KOH, NaOH, H2SO4), presence of organic additives (CH3OH, C2H5OH, CH3COOH), temperature of the electrolytic solution, the active length and immersion depth of the discharge electrode into the electrolytic solution, on the energy efficiency (%), energy yield (g(H2)/kWh), and hydrogen production rate (g(H2)/h) is presented and discussed. This analysis showed that in the cathodic regime of PDSE, the hydrogen production rate is 33.3 times higher than that in the anodic regime of PDSE, whereas the Faradaic and energy efficiencies are 11 and 12.5 times greater, respectively, than that in the anodic one. It also revealed the energy yield of hydrogen production in the cathodic regime of PDSE in the methanol–water mixture, as the electrolytic solution is 3.9 times greater compared to that of the alkaline electrolysis, 4.1 times greater compared to the polymer electrolyte membrane electrolysis, 2.8 times greater compared to the solid oxide electrolysis, 1.75 times greater than that obtained in the microwave (2.45 GHz) plasma, and 5.8% greater compared to natural gas steam reforming. [ABSTRACT FROM AUTHOR]

The article is devoted to the problem of proton-exchange membrane fuel cells (PEMFCs) integration into power supply systems. A hybrid energy complex (HEC) based on PEMFCs and lithium iron phosphate batteries can be used as a reliable energy source. It is necessary to properly determine the PEMFC characteristics in order to develop a PEMFC-based HEC prototype and its control algorithms. This paper presents a 1 kW PEMFC's test results in steady and dynamic modes. The dependences of the average hydrogen consumption per 1 min, the volume of hydrogen for the generation of 1 kWh, the PEMFC efficiency on the load current were obtained and an analysis of these dependences for steady operation modes was performed. A range of load changes beyond which the efficiency of the PEMFC significantly decreased and it was recommended to switch to the joint operation of the PEMFCs and batteries (or only batteries) was established. Diagrams of the PEMFC output voltage during the dynamic changes in loads are presented and an analysis of transient response characteristics was carried out. The air supply fans were found to affect the performance of PEMFCs. [ABSTRACT FROM AUTHOR]

The paper reports a strategy to synthesize Cd0.9Co0.1S nanorods (NRs) via a one-pot solvothermal method. Remarkably, the pencil-shaped Cd0.9Co0.1S NRs with a large aspect ratio and good polycrystalline plane structure significantly shorten the photogenerated carrier transfer path and achieve fast separation. An appropriate amount of Co addition enhances visible light-harvesting and generates a photothermal effect to improve the surface reaction kinetics and increases the charge transfer rate. Moreover, the internal electric field facilitates the separation and transfer of carriers and effectively impedes their recombination. As a result, the optimized Cd0.9Co0.1S NRs yield a remarkable H2 evolution rate of 8.009 mmol·g−1·h−1, which is approximately 7.2 times higher than that of pristine CdS. This work improves the photocatalytic hydrogen production rate by tuning and optimizing electronic structures through element addition and using the photothermal synergistic effect. [ABSTRACT FROM AUTHOR]