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Ni-doped WC/Mo 2 C composites for hydrogen evolution reaction (HER) were synthesized in situ grown on carbon fiber paper (CFP) by molten salt method in argon at 1000 °C for 6 h, named as Ni-xWC-y/2Mo 2 C@CFP. The effects of different W/Mo molar ratios (3:1, 2:1, 1:1, 1:2, 1:3) on the phase composition, microstructures, and HER performances were investigated. The results showed that the W/Mo molar ratio had a synergistic effect in HER of Ni-doped WC/Mo 2 C composites, and as W/Mo molar ratio at 1:1, the composite presented the best electrocatalytic activity. Meanwhile, its surface appeared to have a wrinkle-like structure, and the biphasic heterostructure emerged at the intersection of the dual-phase WC and Mo 2 C lattices. The introduction of a biphasic heterostructure could promote charge transfer and improve HER efficiency. Predictably, the electrocatalysts with the optimal W/Mo molar ratio 1:1 exhibited the best hydrogen evolution performance, needed only 43.7 mV overpotential to reach 10 mA cm−2 current density with a Tafel slope at 21.3 mV dec−1. In this work, the high-efficiency electrocatalysts of Ni-doped 1WC-1/2Mo 2 C@CFP have been prepared, which provides an insight into theoretical research of composite carbon-based electrocatalysts. [ABSTRACT FROM AUTHOR]

This research investigated the hydrogen production and energy conversion from automobile shredder residues (ASRs) and paper mill sludge (PMS) co-gasified in a full-scale fluidized bed gasification plant. The results obtained from full-scale tests provided important information on the feasible assessment of ASRs-to-energy and the selection of alternative technologies for ASRs. Based on the analysis results of produced gas composition, H 2 , CO, and CH 4 composition produced from paper-mill sludge gasified were 4.17%–6.01%, 3.08%–4.32%, 1.71%–2.4%, respectively. Another C 2 gas composition ranged from 2.9% to 3.59%. The heating value of produced gas ranged between 1.64 MJ/Nm3 and 2.18 MJ/Nm3. In the case of 10% ASR addition, the heating value of produced gas was slightly increased to 1.84 MJ/Nm3-2.34 MJ/Nm3. The dioxin emission concentration of flue gas was approximately 0.064 ng I-TEQ/Nm3. It can comply with Taiwan regulation thresholds. The dioxin leaching concentrations of residues derived from gasification were also in compliance with regulation limits by the TCLP test. Meanwhile, in the case of 10% ASRs addition, the dioxin equivalence concentration of gasified residue was nearly 0.002 ng I-TEQ/Nm3. It was far below the current regulation standard limit. In summary, the results of this research have proved the performance of ASRs-to-energy by co-gasified with paper mill sludge using a full-scale gasification plant. The results obtained from this research also provided the information for selecting ASRs alternative technologies and operating full-scale gasifiers in the future. [Display omitted] • This study has confirmed the feasibility of co-gasification of calcium-rich PMS and chlorine-rich ASRs. • Adding 5%–15% of ASRs can maintain the regular operation of the full-scale commercial gasifier. • The synthesis gas has a composition of 4.91 vol% H 2 and 2.06 vol% CO, with a LHV of 1.93 MJ/Nm3. • The HCl emission could comply with regulation thresholds in co-gasification. • Dioxin reformation reduced significantly in co-gasification of PMS and ASRs. [ABSTRACT FROM AUTHOR]

We herein demonstrate polypyrrole decorated micro-porous laboratory filter paper (PFP) as photoanode (PA) for efficient and stable water splitting. The straddling band position with water redox and the measured band gap of ~1.98 eV, make these PFP-PAs effective for water splitting reactions. The results manifest excellent photo-anodic PEC activity of these PFP-PAs, yielding a photocurrent density of ~9.5 mA/cm2 (at 1.23 V vs. RHE) in a three-electrode configuration. The incident photon-to-current efficiency (IPCE) and applied bias photon-to-current efficiency (ABPE) was measured to be 43.19% and ~1%, respectively. Moreover, the robustness of these flexible PFP-PAs was visualized by the provided stability for more than ~160 min in alkaline conditions. The current study provides a proof-of-concept for the realization of a cost-effective, flexible, and efficient paper-based artificial catalyst (like a natural leaf) for solar-driven water splitting. Image 1 • In-situ fabricated polypyrrole based flexible filter paper photo electrode (PFP-PEs). • Exhibit a bandgap of ~1.98 eV and reported as PEs for water splitting. • Photocurrent density of ~9.5 mA/cm2 (at 1.23 V vs. RHE) in 3-electrode system. • IPCE and ABPE was measured to be 43.19% and ~1%, respectively. • PFP-PEs stable for 160 min in alkaline conditions for PEC water splitting. [ABSTRACT FROM AUTHOR]

Paper and pulp mills generate substantial quantities of cellulose-rich sludge materials that are disposed in landfills at a large scale. For sustainability purposes, sludge materials can be bioprocessed to produce renewable fuels and useful chemicals. The enzymatic hydrolysis of cellulose is the process bottleneck that affects the conversion economics directly by using zero-cost raw materials. In order to study and optimize the process, the characteristics of the sludge raw materials should be first evaluated. In this work, sludge samples were obtained from paper mills located at different locations in Wisconsin and Minnesota. Part of the sludge samples was washed (de-ashed) with hydrochloric acid while the other part remained unwashed. The samples were subjected to multiple spectroscopic analyses techniques to evaluate the morphological properties of cellulose fibers and to estimate the total structural carbohydrate content. The results showed that the de-ashing process changed some fiber characteristics and cellulose crystallinity structure in all sludge samples. Sludge sample A (obtained from Kraft pulp and recycled paper mill region) showed a high percentage of fiber, with crystalline cellulose, compared to the other two sludge samples suggesting that sludge A is a valuable source to make value-added products. Aspen Plus mass and energy calculations performed in view of the 'zero' cost and the reliable supply of sludge raw materials producing 2 mol H 2 /mol glucose. Moreover, the results showed that extracting crystalline cellulose from these sludge samples is more profitable than crystalline cellulose made from the other lignocellulosic feedstocks. The results reported here showed that the utilization of these sludge materials would be an economically attractive and promising alternative for the production of hydrogen. Image 1 • A new method for paper mill sludge (PMS) characterization as renewable feedstock. • The deashing step has a major effect on the bioconversion of the PMS. • Studying the crystalline cellulose of the PMS. • A relation between the characterization and potential sugar yield was established. [ABSTRACT FROM AUTHOR]

Developing flexible gas sensors based on reduced graphene oxide (rGO) are highly promising for practical application, however, it is still challenging due to the sacrificed solution-processibility and mechanical properties after reduction. To address this issue, we here introduce solution-processed rGO and designed a flexible hydrogen (H 2) film sensor by coupling with Pd nanoclusters as the activators via direct colloids mixing and subsequent vacuum filtration. The rGO/Pd nanocluster film features with structural compactness, surface homogeneity, excellent mechanical flexibility, high-efficiency output, and simplification of compositing method. In addition, the film sensor exhibited high response value, fast behavior and stable sensing behavior towards high-concentration H 2 compared with bare rGO film owing to the significant activation role of Pd nanoclusters with ultrasmall sizes (average size: 3.3 nm). Conclusively, this work provides an ingenious and effective way for the design of rGO-based flexible sensor, and shows promise for efficient portable and cost-effective monitoring of environmentally H 2 gases leaks. [ABSTRACT FROM AUTHOR]

Exploring noble-free electrocatalyst for hydrogen evolution by electrolysis of water is significant. Herein, porous Ni(OH) 2 @Ni spherical particles are electrodeposited on carbon papers as efficient electrocatalysts for hydrogen evolution reaction (HER) from water. Due to the porous and composite structure, the HER activity of Ni(OH) 2 @Ni/CP is better than the single phase Ni or Ni(OH) 2 particles on the carbon paper. The overpotential of Ni(OH) 2 @Ni/CP is 106 mV at the current density of 10 mA cm−2 and the Tafel slope is 88 mV dec−1. Moreover, the stability of the catalysts tested for 12 h is also good for HER. Furthermore, the small R ct (1.65 Ω) of Ni(OH) 2 @Ni/CP provides the evident for its excellent catalytic performance. The method of electrodeposition provides the controllable uniform size for porous spherical Ni(OH) 2 @Ni particles. Moreover, the Faradaic efficiency for hydrogen evolution is 100%. Image 1 • The overpotential of Ni(OH) 2 @Ni/CP is 106 mV (10 mA cm−2). • The Tafel slope is 88 mV dec−1 and the stability are good for 12 h. • One-pot preparation of Ni(OH) 2 @Ni/CP via through cyclic voltammetry (CV). [ABSTRACT FROM AUTHOR]

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]

Platinum (Pt)‐based electrocatalysts are the benchmark catalysts for hydrogen evolution reaction (HER); however, they are limited by the scarcity and high price. Introducing an adequate substrate to disperse and anchor Pt‐based species is a feasible pathway to improve the utilization efficiency. Herein, a quick and continuous spray drying route is proposed to fabricate 3D crumpled Ti3C2Tx MXene loaded with sub‐nanometer platinum clusters (Pt/MXene). The 3D crumpled structure inhibits the restacking of layered MXene nanosheets and guarantees the fully exposure of Pt clusters. The as‐prepared catalyst exhibits excellent HER performances comparable to commercial Pt/C, including a low overpotential of 34 mV to reach a current density of 10 mA cm−2, a superior mass activity (1847 mA mgPt−1), a small Tafel slope (29.7 mV dec−1), and a high turnover frequency (10.66 H2 s−1). The improved activity of Pt/MXene can be attributed to the charge transfer from Pt clusters to MXene, which weakens the hydrogen adsorption, as evidenced by the density functional theory calculations. The present contribution proposes a novel strategy to anchor low‐mass‐loading sub‐nanometer precious metal clusters on crumpled MXene with fully exposed active sites for catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-doped 1T-2H MoSe 2 /N doped carbon paper was fabricated by a low-temperature nitrogen plasma strategy. • N doping along with 1T phase into the 2H-MoSe 2 can expose more active edge sites and improve electrical conductivity. • N-MoSe 2 /NCP-30 only needs an overpotential of 274 mV to reach −200 mA cm−2 with Tafel slope of 54.7 mV dec-1. Molybdenum selenide (MoSe 2) is considered to be a promising catalyst for seawater hydrogen evolution, but its catalytic activity falls far short of requirements due to its inert surface. Here, self-supported N-doped 1T@2H-MoSe 2 /N doped carbon paper (N-MoSe 2 /NCP) was fabricated by a novel low-temperature nitrogen plasma strategy. In alkaline simulated seawater, the optimized N-MoSe 2 /NCP-30 only requires an overpotential of 274 mV to reach −200 mA cm−2 with Tafel slope of 54.7 mV dec-1, and exhibits stability over 24 h. This work proposes that the introduction of 1 T phase and N dopant into 2H-MoSe 2 using low-temperature plasma strategy can significantly facilitate the exposure of abundant active edge sites and boost the conductivity of MoSe 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • By slow pyrolysis, pulper waste is converted into a stable, carbon-rich material. • Chemical leaching upgrades the carbon-rich solid to a fossil coal substitute. • The process enables to recover more than 90 % of Ca and Al from pulper waste. • By precipitation, a reusable Al-based flocculating agent is obtained. • Clean hydrogen is produced by the reaction between metallic Al and HCl. This work aims to investigate the potentials of integrating slow pyrolysis and chemical leaching to recycle pulper waste (PW), the waste generated by paper mills, and consists of plastics, metallic films, and biobased polymers. The concentration of chlorine and metals is a barrier against PW valorisation by combustion or high temperature thermochemical processes. In this study, PW was tested by slow pyrolysis at 400 °C and 500 °C. Chemical leaching tests were performed by processing both chars in a 1.4 M HCl solution, at 80 °C for 2 h, to remove inorganic compounds and upgrade the char to a coal-like material. Then, precipitation by NaOH was conducted on the leachate. Slow pyrolysis led to a char mass yield around 30 %. Due to the high inorganic matter concentration (almost 36 %, mainly including chlorine, calcium, and aluminium), the char retained only 25 % of the feedstock's chemical energy, while the remaining 75 % was recovered in the pyrogas. Leaching of the 500 °C pyrolysis char led to extract 93 % of aluminium, and almost 100 % of calcium and chlorine, resulting in an upgraded char containing 15.5 % ash, comparable to a fossil coal. By char leaching, the oxidation reaction of aluminium could produce 8 kg hydrogen per dry ton PW. The effectiveness of the precipitated compounds as flocculating agents was demonstrated, enabling a closed-loop recycling in the same paper mill. In conclusion, the proposed process demonstrated to be an effective solution to convert PW into high quality products. [ABSTRACT FROM AUTHOR]

A two-stage thermophilic hydrogen fermentation and mesophilic methane production from paper sludge was successfully explored. The maximum hydrogen and methane potential were 0.165 L/g VS and 0.376 L/g COD effluent , respectively with Clostridium thermocellum augmentation. 63 L of hydrogen and 122 L of methane were recovered from 1 kg Paper sludge (PS, dry weight) with an energy yield of 4.5 MJ/kg PS, 50% higher compared to the single-stage anaerobic digestion (94 L CH 4 , 3.0 MJ/kg PS). The bacterial community of second-stage process was dominated by genus Propionispira , Mesotoga and Aminobecterium with stability, whereas the bacterial structure in single-stage process presented dynamic changes where genus Acetivibrio and Fibrobacter played an indispensable role. However, Genus Methanosaeta , Methanosarcina , Methanobacterium and Methanospirillum existed stably and predominantly in the archaeal community of single-stage and second-stage processes. The present study suggests the potential application of the established two-stage process in valorization of low-value waste biomass. Image 1 • C. thermocellum enhanced two-stage H 2 and CH 4 production from PS was established. • 50% more energy recovery was achieved from two-stage than single-stage. • Archaeal community structure of two BMP tests showed no difference. [ABSTRACT FROM AUTHOR]

The development of noble-metal-free electrocatalysts with high electrocatalytic performance and stability by adopting a scalable route is key to solving the energy crisis. We report a P Ni co-doped Mo 2 C-based electrocatalyst with high hydrogen evolution reaction (HER) catalytic activity prepared by a molten-salt method. Using phosphating times of 2 h and 4 h yielded P-Ni-Mo 2 C-2h and P-Ni-Mo 2 C-4h, respectively, both of which exhibited nanoflower-like structures that provided abundant active sites for the reaction. P-Ni-Mo 2 C-2h possessed good electrocatalytic properties with a low overpotential of only 140.5 mV at j = 10 mA cm−2 and a small Tafel slope of 50.7 mV dec−1 in an alkaline environment. P-Ni-Mo 2 C-2h exhibited excellent stability after 20 h of continuous hydrogen production. The use of an excessively long phosphating time caused a narrow down of spaces formed by nanoflakes, thereby reducing the HER performance of the electrocatalyst. The results of this study provide guidelines for the preparation of high-efficiency P Ni co-doped electrocatalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

• Solid fermentation of paper was successful in lysimeters at 35 and 55 °C. • Homoacetogenesis was prominent under mesophilic conditions. • Alcohol production, ethanol and methanol, was favored under thermophilic conditions. • Dysgonomonas and Ruminococcus were the most abundant populations at 35 °C. • Thermicanus was the main population at a thermophilic temperature of 55 °C. This study explored the hydrolysis and fermentation of paper with hydrogen (H 2) and volatile fatty acid (VFA) recovery using a natural microbial consortium added to lysimeters. Serial dilutions of rumen fluid in natura were performed to obtain a fermentative nonmethanogen consortium, which was used as inoculum in lysimeters under two different incubation temperatures, L1 at 35 °C and L2 at 55 °C. H 2 was detected in both lysimeters: 791.5 mL (L1) and 70.4 mL (L2). In L1, the production of 16,856 mg L−1 acetic acid was likely due to the occurrence of homoacetogenesis. Under thermophilic conditions, L2, a low volume of H 2 was detected, and the highlight was the production of ethanol and methanol at 2289 and 5614 mg L−1, respectively. According to the Shannon index, there was great diversity of microorganism populations in the rumen fluid in natura (6.34) compared with the purified rumen fluid (2.73), L1 (2.67) and L2 (3.21). The most abundant genus in the rumen fluid in natura was Prevotella (37.5 %); in the purified consortium (68.7 %) and L1 (63.8), Dysgonomonas ; and in L2 (88.7 %), Thermicanus. In conclusion, the temperature influenced the microbial community structure, the metabolic route and, consequently, the main byproducts produced by the fermentative activity at 35 °C and 55 °C. [ABSTRACT FROM AUTHOR]

The anomalous heat effect reported in the paper, "Excess heat evolution from nanocomposite samples under exposure to hydrogen isotope gases" by Kitamura et al. published in the Int. J. Hydrogen Energy 43 , pp. 16,187–16,200 (2018), is investigated in the science of the cold fusion phenomenon (CFP) established in these 30 years. It is concluded that the effect is a normal event in the CFP consistent with many events observed in materials with various components and compositions composed of host elements and hydrogen isotopes. • Cold fusion phenomenon means the nuclear reactions in solids with hydrogen isotopes. • Nuclear reactions occur in solids without any acceleration mechanism. • Excess energy accompanied to the nuclear reaction is useful for an energy source. [ABSTRACT FROM AUTHOR]

Pulp and paper mill effluent (PPME), a rich cellulosic material, was found to have great potential for biohydrogen production through a photofermentation process. However, pretreatments were needed for degrading the complex structure of PPME before biohydrogen production. The aim of this study was to gain further insight into the effect of an ultrasonication process on PPME as a pretreatment method and on photofermentative biohydrogen production using Rhodobacter sphaeroides NCIMB. The ultrasonication amplitudes and times were varied between 30–90% and 15–60 min, respectively, and no dilution or nutrient supplementation was introduced during the biohydrogen production process. A higher biohydrogen yield, rate, light efficiency and COD removal efficiency were attained in conditions using ultrasonicated PPME. Among these different pretreatment conditions, PPME with ultrasonication pretreatment employing an amplitude of 60% and time of 45 min (A60:T45) gave the highest yield and rate of 5.77 mL H 2 /mL medium and 0.077 mL H 2 /mL h, respectively, while the raw PPME without ultrasonication showed a significantly lower yield and rate of 1.10 mL H 2 /mL medium and 0.015 mL H 2 /mL h, respectively. The results of this study demonstrated the potential of using ultrasonication as a pretreatment for PPME because the yield and rate of biohydrogen production were highly enhanced compared to the raw PPME. Economic analysis was also performed in this study, and in comparison with raw PPME, the highest net saving was $0.2132 for A60:T45. [ABSTRACT FROM AUTHOR]

The paper investigates the state-of-the-art architecture of photovoltaic systems (PVS) by evaluating the performance of the developed maximum power point tracking (MPPT) algorithm of fuzzy particle swarm optimization (FPSO) for temperate continental latitudes. The material of the paper gives an evaluation of traditional MPPT algorithms in relation to the state-of-the-art FPSO algorithm. The study summarizes the problems of On-Grid PV systems and analyzes methods of solving them by combining them with hydrogen technologies. The paper summaries the experience of observations of climatic factors and solar resources on the example of the Russian Federation. Thus, in 2023, the average winter temperature exceeded the norm by 4.7 °C, and the average summer temperature exceeded the norm by 4.9 °C compared to 2022. The paper analyses the level of insolation, which increased by 0.03 kWh/m2 by regions of Russia for the period 2022–2023. The experimental part of the work was carried out at the solar power plant (SPP) «Kalmykskaya» with coordinates 53.422832 north latitude and 55.266895 east longitude. The watt-volt field characteristic of photovoltaic modules (PVM) connected to the inverter was obtained experimentally. When compared, the correlation coefficient between the experimental power (P) and voltage (U) of the panels was found to be higher than that of the ideal panels, 0.933 versus 0.914. The correlation coefficient between the ideal P(U) function and the experimental one is (−0.475). The data for calculating the coefficient of performance (COP) of the implemented MPPT algorithm was also obtained experimentally, which was about 98.7%. The reliability of the data used in the calculations was confirmed by two independent means of measurement, the difference of the obtained results was less than 1%. In the last part of the experiment of this study, the dependence of insolation in a given geographical point on the generated PV field power was evaluated. The correlation coefficient was 0.47, while the inverter output voltage was maintained in the nominal range of (600 ± 20%)V. Thus, the authors of the study experimentally proved the efficiency of using MPPT on FPSO in temperate continental climate with duration of sunshine T = 1850 h per year. The effectiveness of the FPSO algorithm under the conditions of inverter distance from the common point of the DC switching cabinet (DСCC) has been confirmed. The effectiveness of the MPPT algorithm based on FPSO under conditions of partial shading, increased cloud cover and increased air temperature is concluded. Using the description of the current architecture of On-Grid SPP, the authors draw attention to the impossibility of operation of such systems without the presence of voltage in the reference network. In addition, the impossibility of the system operation at the value of PVM power over 1500 kW and at the voltage of panels less than 900 V is noted. To modernize the existing PVS architecture, for the first time, the use of a DCCC and an inverter with implemented MPPT on the FPSO in combination with a hydrogen (H 2) production unit and nickel-hydrogen (Ni–H 2) batteries is proposed. The researchers propose that when the PVM field voltage is below 900 V and when the PVM field power exceeds 1500 kW, energy can be diverted to H2 generation or to charge Ni–H2 batteries via a DCCC controller. Such an architecture will improve the continuity and efficiency of the PVS, reduce the carbon footprint, and allow the PVS to be used as an industrial uninterruptible power supply (UPS). The authors see the lack of standardization of implemented projects based on the ESG principle as the main problem of alternative energy development. [ABSTRACT FROM AUTHOR]

This paper examines the problem of synthesizing a two-loop control system for a three-phase voltage source inverter designed for an autonomous power supply system. This type of DC/AC converters is an essential part of power supply systems with renewable energy sources as primary sources, and, accordingly, must corresponds to the requirements for the electric power quality. These requirements are met through circuit design solutions, as well as through the construction of high-precision automatic control systems. The system integrates: a hydrogen electrolyzer, a hydrogen storage system, and a hydrogen fuel cell. The paper proposes a method for calculating the parameters of PI controllers with resonant components, based on the time-scale separation method and allowing independent adjustment of the controller components. The introduction of a resonant component ensures high tracking accuracy for a desired main voltage harmonic and selective suppression of external harmonic influences. The proposed approach allows to synthesize an automatic control system that significantly improves the quality of the voltage inverter output parameters. [ABSTRACT FROM AUTHOR]

With the wide application of hydrogen, the research related to 70 MPa pressure level hydrogen storage tank is very important. This paper takes the 70 MPa hydrogen storage tank in the hydrogen refueling station as the research object, and analyses the diffusion characteristics of hydrogen after leakage from the tank under different wind conditions by FLUENT. Studies find that after hydrogen ejects to the obstacle by the effect of high-pressure, it transforms to be dominated by the simple diffusion and the wind condition. The ambient wind helps to reduce the volume fraction of hydrogen. This paper proposes risk mitigation measures based on the distribution of the flammable clouds — installing nitrogen outlets and reducing the height of the enclosure. The volume of flammable clouds is reduced from about 2.72 m3 to less than 0.045 m3 after adding measures, which proves the feasibility of the measures. • A hydrogenation station model is established to simulate the leakage of a 70 MPa hydrogen storage tank. • The diffusion of hydrogen under different wind conditions is compared. • Risk mitigation measures based on the distribution of flammable clouds are proposed and validated. [ABSTRACT FROM AUTHOR]

A reduction in greenhouse gases has become an inescapable requirement. An effective scenario for achieving carbon neutrality is to develop a hydrogen economy. Its success, however, requires strict control of the different processes involved in planned hydrogen chains. The energy chain considered in this paper is a stationary application which involves the production of hydrogen by electrolysis (a power-to gas process) and its combustion in gas turbine combined cycles to generate electricity (a gas-to-power process). In such applications, the need is twofold: (i) to control the risk of explosive atmospheres by performing safe gas detection in the presence of hydrogen and (ii) to secure the reliability of all chain processes using hydrogen-rich gases by achieving reliable analyses of these gases. This paper is dedicated to the development of hydrogen energy to decarbonize the thermal production of electricity. We will first describe the hydrogen chain that would best suit the power generation sector. Then, we will highlight the properties of hydrogen that are critical for its reliable operation. Finally, we will review the sensing technologies suitable for hydrogen-containing fuels. This review paper was published as part of a Joint Industrial Project (JIP) aimed at enabling the safe and reliable deployment of hydrogen energy. [ABSTRACT FROM AUTHOR]

Hydrogen is emerging as a critical player in transitioning to sustainable and renewable energy systems, serving roles in energy storage, grid balancing, and decarbonization. This paper explores various aspects of hydrogen, including its production through renewable-electricity-driven electrolysis, advanced storage techniques, and incorporation into current energy systems. It highlights primary electrolysis methods like PEM and alkaline, noting their improved efficiency and cost-effectiveness. Various hydrogen storage methods, such as physical, chemical, and advanced porous materials, are examined for their benefits and limitations. The review further explores hydrogen's integration into grid storage systems and microgrids to enhance energy reliability. It discusses hydrogen's application in fuel cells for electricity generation, focusing on technological advancements that improve efficiency and reduce costs. Additionally, the paper underscores hydrogen's crucial role in reducing CO 2 emissions in industrial processes like steel production and its use in residential and commercial energy supply through combined heat and power systems. Economic aspects and supportive policies from regions are analyzed, highlighting the global efforts and policies supporting the potential hydrogen in renewable energy systems. This analysis emphasizes hydrogen's comprehensive role in enhancing renewable energy systems and achieving global sustainability objectives, providing a thorough review of recent progress and challenges. • Identifies PEM and alkaline as efficient electrolysis methods. • Analyzes varied H 2 storage options for mobility and stationarity. • Highlights advancements in H 2 fuel cells for vehicles. • Discusses global policies supporting H 2 integration. • Reviews economic impacts of scaling H 2 infrastructure. [ABSTRACT FROM AUTHOR]

The study of hydrogen concentration distribution law of hydrogen-doped methane pipeline is directly related to the safety and stability of hydrogen-doped methane pipeline network. Based on the theory of fluid dynamics, this paper established a model of hydrogen-doped methane pipeline and simulated the operation and shutdown status of hydrogen-doped methane pipeline by adopting the computational fluid dynamics method and selecting the mixture multiphase model and standard k - ε turbulence model. This paper investigates the hydrogen concentration distribution law in hydrogen-doped methane pipelines as well as the influence law of different hydrogen-doping ratios, operating flow velocities, operating pressures, shutdown time and gas usage on the hydrogen concentration distribution in gas pipeline. The results show that: under the operation condition, there is a weak uneven distribution of hydrogen in the pipeline, the hydrogen-doping ratio, flow velocity, pressure on the hydrogen volume fraction of the change in the 0.9% or less, the effect can be ignored; in the shutdown status, there is a clear stratification phenomenon, the hydrogen-doping ratio increased from 10 to 25%, the change in the volume fraction of hydrogen in the 11.2% or less, a positive correlation; with the extension of the shutdown time to 900s, the pipeline firstly appeared obvious stratification phenomenon in the branch pipe, the thickness of the gas with hydrogen volume fraction above 40% on the upper wall surface of the branch pipe increased to 0.7 mm, and after the shutdown time was extended to 10 h, obvious stratification phenomenon appeared in the main pipeline, and the volume fraction of hydrogen near the top of the main pipe of about 16.5 mm was above 30%, which was positively correlated; In the shutdown status, the shutdown time has the greatest effect on the stratification phenomenon in the pipe, followed by the hydrogen-doping ratio, and the gas usage has the least effect. [ABSTRACT FROM AUTHOR]

This paper investigated the opportunities and challenges of integrating ports into hydrogen (H2) supply chains in the context of Australia and Japan because they are leading countries in the field and are potential leaders in the upcoming large-scale H2 trade. Qualitative interviews were conducted in the two countries to identify opportunities for H2 ports, necessary infrastructure and facilities, key factors for operations, and challenges associated with the ports' development, followed by an online survey investigating the readiness levels of H2 export and import ports. The findings reveal that there are significant opportunities for both countries' H2 ports and their respective regions, which encompass business transition processes and decarbonisation. However, the ports face challenges in areas including infrastructure, training, standards, and social licence, and the sufficiency and readiness levels of port infrastructure and other critical factors are low. Recommendations were proposed to address the challenges and barriers encountered by H2 ports. To optimise logistics operations within H2 ports and facilitate effective integration of H2 applications, this paper developed a user-oriented working process framework to provide guidance to ports seeking to engage in the H2 economy. Its findings and recommendations contribute to filling the existing knowledge gap pertaining to H2 ports. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) have become an integral part of modern life, serving both civilian and military applications across various sectors. However, existing power supply systems, such as batteries, often fail to provide stable, long-duration flights, limiting their applications. Previous studies have primarily focused on battery-based power, which offers limited flight endurance due to lower energy densities and higher system mass. Proton exchange membrane (PEM) fuel cells present a promising alternative, providing high power and efficiency without noise, vibrations, or greenhouse gas emissions. Due to hydrogen's high specific energy, which is substantially higher than that of combustion engines and battery-based alternatives, UAV operational time can be significantly extended. This paper investigates the potential of PEM fuel cells as an alternative power source for electric propulsion in UAVs. This study introduces an adaptive, fully functioning PEM fuel cell model, developed using a reduced-order modeling approach and optimized for UAV applications. This research demonstrates that PEM fuel cells can effectively double the flight endurance of UAVs compared to traditional battery systems, achieving energy densities of around 1700 Wh/kg versus 150–250 Wh/kg for batteries. Despite a slight increase in system mass, fuel cells enable significantly longer UAV operations. The scope of this study encompasses the comparison of battery-based and fuel cell-based propulsion systems in terms of power, mass, and flight endurance. This paper identifies the limitations and optimal applications for fuel cells, providing strong evidence for their use in UAVs where extended flight time and efficiency are critical. [ABSTRACT FROM AUTHOR]

Nowadays, hydrogen is gaining attention as one of the green energy alternatives within transition to a zero-emission economy. Increasing demand for hydrogen and its production has prompted the development of low-carbon strategies and technologies for hydrogen generation from hydrocarbons. This paper provides a thorough analysis of traditional and innovative methods for hydrogen production from fossil feedstock, reviewing the critical aspects and recent advancements in the field. The paper emphasizes the potential of in situ hydrogen generation as the most promising method, taking into account CO2 emission concerns. Additionally, this study explores the use of software packages for modeling hydrogen production, outlining their advantages and disadvantages and proposing the most favorable software for in situ hydrogen generation from hydrocarbons. Subsequent analysis sheds light on the effectiveness, economic viability, environmental impact, and future perspectives of various hydrogen production technologies. • Overview of hydrogen production technologies: conventional and innovative methods. • Key issues and best practices of the latest experimental and numerical studies. • Comparative analysis of various hydrogen production technologies and approaches. • Subsurface hydrogen generation has a great development potential. • There are methods for clean hydrogen production from hydrocarbon feedstock. [ABSTRACT FROM AUTHOR]

Hydrogen transfer leaks are one of the most important life-limiting faults in polymer electrolyte membrane fuel cells (PEMFCs). Hydrogen transfer leaks result in a reduction in the amount of oxygen available in the cathode (air) channel, with large leaks resulting in oxygen starvation and hydrogen emission. This paper aims to develop an adaptive extended Kalman filter (EKF) to estimate the unknown oxygen concentration, which is then used to infer hydrogen leaks. To this end, the paper first develops the lumped model of the fuel cell from a pseudo-2D model of a fuel cell. Next, a (non-adaptive) EKF is developed to estimate the fuel cell states under both normal and oxygen-starved conditions. The adaptive EKF is then implemented by adding the unknown hydrogen leak to the list of estimated states. Finally, the paper demonstrates the efficacy of the proposed adaptive EKF by using it to accurately estimate unknown hydrogen leaks in a high-fidelity virtual fuel cell under excessively noisy conditions. • Adaptive extended Kalman filter under normal and starved conditions. • Detects leaks under the presence of excessive noise. • Uses transient model of starved fuel-cell capturing voltage. • Based on previously validated pseudo-2D model. • Transient response agrees with simulated experiments. [ABSTRACT FROM AUTHOR]

Hydrogen as a clean energy to deal with carbon emissions has been favored by many scholars, while the problems of low efficiency and high energy consumption in the process of liquefaction storage and transportation have become one of the important factors restricting the development of it. The combination of heat exchanger and ortho-para (O–P) hydrogen converter has attracted considerable attention as a high efficiency and low energy consumption technology. In this paper, based on the catalyst-filled spiral wound heat exchanger (CSWHE) and coupled with ortho-para hydrogen conversion, the flow and heat transfer characteristics of gaseous hydrogen are studied. Firstly, low-temperature O–P hydrogen catalytic conversion experiments and flow characteristics experiments were carried out by filling catalyst in the heat exchange tube. and an equation for calculating pressure drop in the section filled catalyst was proposed. Secondly, a new numerical model was established validated by the experiments. The influence of catalyst on heat transfer and the effects of velocity on the heat transfer performance and O–P hydrogen conversion efficiency were studied by numerical simulation. Finally, this paper analyzed the significant factor affecting the para hydrogen content at outlet: reaction time. And an equation for calculating para hydrogen content at outlet with reaction time was proposed. This study is expected to provide a reference for the design of CSWHE. • An isothermal reactor is designed and employed to low-temperature ortho and para hydrogen catalytic conversion experiments. • A new pressure drop calculation equation for porous region is proposed by modifying Ergun equation. • A new numerical model is established to study the coupling mechanism of flow and heat transfer. • The key factor affecting the catalytic conversion of ortho and para hydrogen is pointed out: reaction time. [ABSTRACT FROM AUTHOR]

As a paradigm of clean energy, hydrogen is gradually attracting global attention. However, its unique characteristics of leakage and autoignition pose significant challenges to the development of high-pressure hydrogen storage technologies. In recent years, numerous scholars have made significant progress in the field of high-pressure hydrogen leakage autoignition. This paper, based on diffusion ignition theory, thoroughly explores the mechanism of high-pressure hydrogen leakage autoignition. It reviews the effects of various factors such as gas properties, burst disc rupture conditions, tube geometric structure, obstacles, etc., on shock wave growth patterns and autoignition characteristics. Additionally, the development of internal flames and propagation characteristics of external flames after ignition kernels generation are summarized. Finally, to promote future development in the field of high-pressure hydrogen energy storage and transportation, this paper identifies deficiencies in the current research and proposes key directions for future research. [ABSTRACT FROM AUTHOR]

Pulp and paper industry primary sludge being largely composed of lignocellulosic fibres, it could be used as carbon source by bacteria having cellulolytic capability. The aim of this study was to evaluate the use of cellulose contained in this type of sludge for Clostridium thermocellum to produce ethanol, hydrogen and cellulases. In an ATCC 1191 medium containing 5 kg m −3 dry primary sludge from recycled paper mill, batch culture reached stationary phase after 2 days. All of the available cellulose was hydrolysed after 60 h of incubation, with a final pH of 5.83. Metabolites produced after 60 h of fermentation were acetate (8.50 mol m −3 ), ethanol (11.30 mol m −3 ), lactate (8.75 mol m −3 ), formate (0.27 mol m −3 ), hydrogen (11.20 mol m −3 ) and carbon dioxide (18.41 mol m −3 ). Cellulase activity was detected in the supernatant after 36 h, with a maximal activity of 0.25 U cm −3 at 72 h. Pulp and paper primary sludge appeared to be a readily usable substrate for C. thermocellum at this concentration, yielding both potential biofuels (hydrogen and ethanol) as well as active cellulases. [ABSTRACT FROM AUTHOR]

Hydrogen fuel is a non-toxic and source-abundant energetic system, but for its applications in the industry, several issues related to its storage must be resolved. Compounds like NaBH 4 appear as promising hydrogen sources, while can release the latter rapidly under controllable conditions with the use of heterogeneous catalyst systems. In this work, we synthesized a Ni–CoP catalyst by electrodeposition in a three-step process on carbon paper as support. The materials were characterized via SEM-EDS, XRD, and XPS techniques, while the hydrogen evolution reaction (HER) from alkaline NaBH 4 solutions was tested as a batch experiment. Ni–CoP catalyst showed a high amount of H 2 generated in a short time (∼550 mL in 1 min) and remained at 78 and 54% of its initial performance after respectively 100 and 300 h of a continuous hydrolysis process. Our catalyst revealed exceptional performance and stability at higher temperatures and a long process time, which have been a rare subject of investigation in other reports for NaBH 4 hydrolysis in the past. This work paves a new perspective in studying catalysts for hydrogen generation from borohydrides. [Display omitted] • Ni–CoP catalyst was electrodeposited on a carbon support. • Material characterization proved the formation of desired active layers. • High efficiency and stability of the catalyst for a long-term NaBH 4 hydrolysis was revealed. [ABSTRACT FROM AUTHOR]

Biological hydrogen production from the anaerobic fermentation of ultrasonic-pretreated paper mill sludge started at a pH of 5.5 and a temperature of 36.5°C. When the sludge reaction time (SRT) was 32 h, the organic loading rate (OLR) was 3,000 mg chennai oxygen demand (COD)·L-1·d-1, and the hydrogen production yield was 620.8 mL H2/g COD. The Gompertz equation was used for regression analysis of accumulated hydrogen yield, which indicated that R2 was 0.99. Hydrogen was produced by typical ethanol-type fermentation and the utilization of organic material was 31.8%. [ABSTRACT FROM AUTHOR]

Gassing problems and premature insulation failures in wind turbine transformers indicate reliability concerns about the insulation of such components. This fact necessitates investigating degradation of transformer insulation systems under high-dV/dt pulse voltages that exist in today's wind energy plants. For this purpose, PD activity, generally assumed to be the main long-term cause of insulation deterioration, needs to be analyzed. This work evaluates the effects of impulse voltage parameters such as rate of rise and repetition frequency on inception voltage and intensity of PD activities. PD parameter measurement under high-dV/dt voltages is challenging due to interferences from fast oscillations, and difficulties of PD energy measurements. To avoid such issues, which are related to electromagnetic detection methods under pulse energization, this work uses a chemical approach to compare PD activities, based on the rate of hydrogen generation in a controlled test chamber with oil/paper samples. Gas monitoring of the oil containing impregnated paper samples reveals that a faster rate of rise increases PD energy as well as inception voltage. Results based on experiments conducted in small oil chambers show good correlation between the amount of hydrogen detected and PD energy level; hence it can be used as a benchmark for comparing PD energy levels under various impulse waveforms. [ABSTRACT FROM AUTHOR]

In order to improve the hydrogen sensing of transition metal oxide nanomaterials at room temperature, MoO 3 nanowire paper was prepared and used as a hydrogen sensing materials on substrate. In this paper, orthorhombic phase, ultra-long (∼1 mm) MoO 3 nanowires were synthesized through conventional hydrothermal method at 260 °C for 96 h. A flexible nanowires paper with size of 200 mm × 300 mm was obtained by further self-assembly formation process of pure α-MoO 3 nanowires in aqueous solution on hydrophobic substrate, and the thickness of paper can be controlled depend on the concentration of disperse nanowires. A novel hydrogen sensor with sensing area of 10 mm × 10 mm was obtained after Pt interdigital electrodes (IDE) deposited on the surface of α-MoO 3 nanowires paper and transferred into ceramic circuit board (CCB) without any surface modification. The response and recovery time are about 3.0 and 2.7 s toward 1.5% H 2 , respectively. The sensors also show good selectivity toward H 2 against other reduce gas, such as C 2 H 5 OH, CO and CH 4 . Large amounts of the porous structures and high specific surface of nanowires paper is beneficial to the absorption of oxygen molecules, which would lead to the high sensitivity, fast response and recovery speed of sensor at room temperature. MoO 3 nanowires paper sensors have excellent stability and reliability, which could work for 5.56 years at room temperature. [ABSTRACT FROM AUTHOR]

The escalating demand for renewable energy solutions and the imperative for efficient energy storage mechanisms have catalyzed the evolution of Power-to-X (PtX) technologies. Germany has the most PtX projects, accounting for 44% of all projects that have been reported. PtX encompasses a spectrum of processes engineered to convert surplus renewable energy into versatile energy carriers or chemical commodities, such as hydrogen, methane, or synthetic fuels. The Paramount to this domain is to synergistically harness renewable energy sources and hydrogen carriers to curtail waste and bolster sustainability. Central to achieving this synergy is the effective control of PtX processes, ensuring optimal performance, cost efficiency, and seamless integration within existing energy frameworks. This paper delves into the control processes and environmental prerequisites within the PtX landscape, elucidating key challenges, and strategies within this dynamic realm. While providing an initial overview of fundamental PtX process chains, this paper accentuates the critical role of geographical considerations. Subsequently, it conducts a thorough analysis of equipment modeling challenges, addressing performance metrics, operational requisites, and capital investments, particularly focusing on methanol and hydrogen production and storage. Through holistic examination, this paper endeavors to delineate the evolving landscape of PtX control processes and conditions, advancing our understanding of this expanding field. [Display omitted] • Comprehensive overview of PtX control process, challenges, strategies, and advancements. • Overview of PtX process chains and geographical conditions. • Analysis of equipment modeling challenges for methanol and hydrogen. • Addressing crucial storage challenges in PtX system. • Exploration of diverse influences on PtX control processes. [ABSTRACT FROM AUTHOR]

Stationary hydrogen energy-based power plants generating electricity to supply high-powered plug-in electric vehicles (PEVs) have recently become popular in renewable energy-based power plants. Besides, in a PEV charging station, various types of powered charge devices can be established such as DC fast chargers or 3.7 kW, 7.4 kW, 11 kW, and 22 kW AC chargers. This paper introduces a demand-side management-oriented optimal charging strategy that includes two stages for PEVs in a hydrogen energy-based microgrid. The paper focuses on two stages to execute an optimal charging of PEVs in compliance with their users' requests and satisfaction and considering the power system loading. It is assumed that there are three types of chargers in the PEV charging station and the users. In the first stage randomly created requests are classified by an ensemble learning classifier method that performs higher performance classification by combining the results from multiple classifiers in a machine learning classification. The second stage schedules the PEVs according to the classification results and users' requests. To test the proposed system, first random requests are created then they are sent to the classifier, and the results of classifiers are scheduled in each other. The demand-side management-oriented charge scheduling and managing strategy which includes the proposed two stages has been compared with non-managed cases. Case study results reveal that the proposed approach provides 52.1% peak load reduction and 72.3% valley filling improvement by the SOS algorithm. The results highlight the advantages of the proposed system in terms of peak reduction and valley filling. [Display omitted] • A new intelligent decision-maker method is proposed for DSM in a microgrid. • Proposed method is developed for a stationary hydrogen energy-based power plant. • The optimal DSM of EVs is investigated with a hybrid ML method. • RUSBoost and SOS Algorithms-based Hybrid Intelligent Decision Maker is developed. • It provides 52.1% peak load reduction and 72.3% valley filling improvement. [ABSTRACT FROM AUTHOR]

Hydrogen is an ideal energy source and plays an important role in increasingly global energy issues and environmental problems. Liquid hydrogen (LH2) has many advantages over other storage methods, especially in terms of energy density. However, it may cause enormous harm once it leaks accidently. LH2 leakage is a complex multiphase process involving evaporation, condensation, transfer of mass and heat, and dispersion. In order to study LH2 transportation and storage systems safety, a research project has been carried out to develop a 3D numerical model using an open-source CFD code, OpenFoam, for investigating LH2 accidental release scenarios. Since the release of LH2 is a very complex process, our strategy is to study it step by step. Therefore, in this paper we present our research work at the first stage, a dispersion process of room-temperature gaseous hydrogen without multiphase flow. A small-scale hydrogen release conducted by Sandia National Laboratories is simulated. In this experiment, room-temperature gaseous hydrogen is injected upwards into the air from a small hole with a 1.91 mm diameter. The situations of Froude (Fr) number = 99, 152, and 268 are studied, respectively. The behavior of hydrogen at different Fr numbers is discussed. When high-speed hydrogen enters the air, the speed and concentration of hydrogen decrease rapidly. In addition, the greater the speed, the faster it decays. The result shows a close range of hydrogen reach. Details about the numerical model are introduced. The simulation results are used to verify the validity of the developing numerical model for dispersion and mixing of multi-species. The simulated concentrations and velocity distribution are analyzed and compared with experimental data. The simulation shows a good agreement with the data of Sandia National Laboratories. The agreement between experiments and simulations is measured using the Pearson correlation coefficient (>0.98), which indicates excellent consistency. In the next step, we will integrate the multiphase flow and phase change into the current model. The phase change of liquid hydrogen and air will be simulated to study the release of liquid hydrogen. • Using the open-source CFD code OpenFOAM for simulation of hydrogen jet. • A good agreement between the simulations results and experimental data has been found in this paper. • When high-speed hydrogen is injected into the air, both velocity and concentration drop rapidly. • Final concentration is not sensitive to different injection velocity. [ABSTRACT FROM AUTHOR]

This paper explores a novel method of focuses on utilizing ammonia as a hydrogen carrier that can be decomposed to produce hydrogen, the combustion of which produces steam for generating power in turbines. The simulation for such a process is performed on ASPEN Plus software. The key steps include compressing the ammonia and passing it through a fluidized bed reactor (FBR) for its decomposition, subsequently compressing the products before combusting the hydrogen with compressed air in a combustor and extracting power from the hot products through a series of turbines. The article examines in detail the effect of different parameters on the performance of the individual components as well as the overall process. Specifically, considerable emphasis is placed on the effects of varying pressures and temperatures on the functioning of the FBR at different catalyst loadings, their effects on the combustor performance and the dependence of the overall process on the air flowrate in the combustor. The comprehensive analysis elucidated on the energy efficiency of the process and it identified conditions at 2 bar pressure and 550 °C temperature as being the most favorable for ammonia decomposition and subsequent turbine power output while lean hydrogen combustion with excess air making the inlet hydrogen concentration less than 20% resulted in optimum temperatures at the turbine inlet. • The paper explores ammonia as a hydrogen carrier in the power plant industry through ASPEN PLUS process simulations. • The initial step is to decompose ammonia into nitrogen and hydrogen in a fluidized bed reactor, the optimum operating condition of which turns out to be 2 bar pressure and 550 °C. • The next steps involve mixing air with the decomposition products, pressurizing them to 40-60 bar, combusting hydrogen in a plug flow reactor to produce steam and finally expanding it in a series of turbines to generate power. • Detailed flow and more importantly, energy analysis of all the process units show ammonia as a very effective hydrogen carrier for applications in power plants. [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]

Development of a hydrogen economy as part of the response to the challenges especially of climate change and energy security will depend upon the solution not only of technical problems, but also of legal and regulatory problems. Whereas these are most obviously related to health and safety, this paper focuses on the fact that support for hydrogen is increasingly contingent upon the method of its production and specifically upon the level of greenhouse gas emissions involved. The paper examines emerging arrangements in Australia and the EU as examples of likely future key hydrogen exporters and importers, respectively. [ABSTRACT FROM AUTHOR]

The power system using hydrogen fuel cells (FCs) as the primary energy source holds significant potential for applications in emergency fields such as post-disaster relief and outdoor power supply. The operational environment of the FC emergency power supply system (FCEPSS) is challenging, with long continuous operation time, difficulties in hydrogen supply, high maintenance costs, and, accordingly, requirements for hydrogen consumption and useful life of FCs are heightened. Hence, this paper proposes a multi-objective energy management strategy (EMS) for FCEPSS. First, the structure of FCEPSS is designed based on the demand analysis in emergency scenarios. Then, the hydrogen consumption and life degradation models of FCEPSS are established. Aiming at the multi-objective optimization problem of minimizing hydrogen consumption and life degradation value in the FCEPSS, an improved multi-objective optimization algorithm is proposed. This paper converts complex constraints into the penalty term and incorporates it as one of the objectives, constructing a three-objective optimization model. To enhance the solution of multi-objective optimization problems, an improved strategy based on relaxation-tightening and three-objective sorting is proposed. Combining the fast non-dominated sorting genetic algorithm-II and the above improved strategy, an improved multi-objective optimization algorithm (IMOOA) is constructed. In the simulation, the advantages of the proposed IMOOA algorithm are verified. In the experimental part, compared with the logical threshold strategy, the proposed strategy saves 0.60% of hydrogen consumption and reduces 5.65% of life degradation within 24 h, respectively. Finally, the superiority of the multi-objective EMS utilizing the IMOOA is demonstrated. [Display omitted] • The demand analysis and scheme design of fuel cell emergency power supply system are carried out. • A multi-objective energy management strategy for low hydrogen consumption and long useful life is designed. • An algorithm based on the relaxation-tightening and three-sorting principle is constructed. [ABSTRACT FROM AUTHOR]

A green hydrogen (H 2) economy requires a sustainable, efficient, safe, and widespread infrastructure for transporting and distributing H 2 from production to consumption sites. Transporting a hydrogen/natural gas (H2NG) mixture, including pure H 2 , through the existing European natural gas (NG) infrastructure is considered a cost-effective solution, particularly in the transitional phase. Several reasons justify the H2NG blending option. The NG infrastructure can be efficiently repurposed to transport H 2 , by blending H 2 with NG, to operate as H 2 daily storage, matching production and demand and to enable large-scale seasonal H 2 storage. Although many benefits exist, the potential of existing NG grids for transporting and distributing green H 2 may face limitations due to technical, economic, or normative concerns. This paper focuses on the state of the art of the European NG transmission and distribution metrology normative framework and identifies the gaps to be filled in case of H2NG flowing into the existing grids. The paper was revised to provide a comprehensive analysis of the practical implications resulting from the H2NG blend option. [Display omitted] • The RePowerEU planned hydrogen production and utilization to achieve decarbonization targets. • The existing gas grid is considered for transporting and distribute large hydrogen amounts. • The European Committee for Standardization defined Standards on gas grid instrumentation. • A review of the European natural gas grid metrology normative was carried out in THOTH2 Project. • Standards need to be revised to account for hydrogen-natural gas mixtures transportation. [ABSTRACT FROM AUTHOR]

Carbon-based single-atom catalysts, a promising candidate in electrocatalysis, offer insights into electron-donating effects of metal center on adjacent atoms. Herein, we present a practical strategy to rationally design a model catalyst with a single zinc (Zn) atom coordinated with nitrogen and sulfur atoms in a multilevel carbon matrix. The Zn site exhibits an atomic interface configuration of ZnN4S1, where Zn's electron injection effect enables thermal-neutral hydrogen adsorption on neighboring atoms, pushing the activity boundaries of carbon electrocatalysts toward electrochemical hydrogen evolution to an unprecedented level. Experimental and theoretical analyses confirm the low-barrier Volmer-Tafel mechanism of proton reduction, while the multishell hollow structures facilitate the hydrogen evolution even at high current intensities. This work provides insights for understanding the actual active species during hydrogen evolution reaction and paves the way for designing high-performance electrocatalysts. [ABSTRACT FROM AUTHOR]

The effects of N/C, P/C and Fe/C ratios on dark fermentative hydrogen gas production from activated carbon treated WPT hydrolysate were investigated using Box–Behnken statistical experiment design. N/C, P/C and Fe/C ratios were chosen as independent variables while the H 2 yield and SHPR were set as the objective functions. H 2 yield and SHPR functions were described by two quadratic model functions. The addition of a proper amount of N, P and Fe to the fermentation media was found to be essential to enhance the H 2 production performance. Linear and interaction terms of N/C and Fe/C did have a significant effect on the H 2 yield in the model function. However, the SHPR was significantly affected by the linear and interaction terms of N/C and P/C. The most convenient N/C, P/C and Fe/C ratios resulting maximum H 2 yield (0.656 mol H 2 /mol glucose) and SHPR (241.64 mL H 2 /g biomass.h) were determined as 0.05, 0.09 and 0.003 (w/w), respectively. [ABSTRACT FROM AUTHOR]

In recent years, the catalyst efficiency of hydrogen evolution reaction (HER) has been extensively studied. However, the stability of catalysts at high current densities is still a challenge. Herein, layered Ni−Co−P was electrodeposited on carbon fiber paper (CFP) via cyclic voltammetry (CV). This low‐cost electrode exhibits high efficiency and excellent durability for HER in 1 M KOH. To achieve current densities of 10, 100, 500, and 1000 mA cm−2, Ni−Co−P/CFP required overpotentials of 49, 95, 170, and 295 mV, respectively. The layered structure allows the catalyst to fall off layer by layer. After the outer layer of catalyst falls off, the inner layer of catalyst will be exposed to continue working. After 300 h of HER at 1000 mA cm−2, Ni−Co−P/CFP still has a regular morphology and high efficiency. Our work shows that layered Ni−Co−P/CFP has excellent prospects for practical applications. [ABSTRACT FROM AUTHOR]

The operational cabin of hydrogen tube bundle containers (HTBCs) is susceptible to vibration and fatigue loads during transportation, which may result in hydrogen leakage and deflagration accidents. In this paper, a three-dimensional (3D) computational fluid dynamics (CFD) model is developed to simulate the effects of leakage diameter, leakage pressure, leakage direction and position on hydrogen leakage and diffusion in the operational cabin of HTBCs. The results demonstrate that the formation of vortex recirculation zones leads to the accumulation of flammable gas cloud (FGC) in the operational cabin. The medium leakage diameter (1.5 mm) and higher leakage pressure (20 MPa, 35 MPa) cause the operational cabin to be filled with FGC within 5 s, requiring the operational cabin to be designed with no possible ignition source inside. In addition, when hydrogen leaks from the +Z direction, the sensor responds within 0.31 s, which is 1.7 s earlier than the response time in the -Z direction, indicating that the existing sensor layout cannot meet the requirements of fast response. When the leak position (L 3) is close to the vent, the FGC volume proportion at 2 s is 19.3 % and 15.88 % lower than that of L 1 and L 2 , respectively, indicating that the leak position close to the vent can effectively slow down the accumulation of FGC. The research results have implications for the safety design of operational cabin of HTBCs, the layout of hydrogen sensors and vents, and the emergency response measures for hydrogen leakage. [Display omitted] • Numerical simulation reveals hydrogen leakage and diffusion behavior of tube bundle containers during transport. • Vortex recirculation zones cause flammable gas cloud accumulation in operational cabins. • Medium leakage (1.5 mm) and high pressure can fill the cabin with flammable gas cloud in 5 s. • Leakage direction and position affect hydrogen sensor response time. • The addition of hydrogen sensors and vents can reduce the risk of explosion. [ABSTRACT FROM AUTHOR]

Fuel cell technology emerges as a promising green solution, offering mitigation to global warming, air pollution, and energy crises. This eco-friendly approach is witnessing a surge in adoption within the automotive sector, with fuel cell buses, cars, scooters, forklifts, and more, becoming increasingly prevalent. The automobile industry has been rapidly advancing fuel cell technology, inching closer to the commercialization of fuel cell vehicles. As various technical hurdles are surmounted and costs are reduced, fuel cell vehicles are poised to become a competitive force in the automobile market, presenting an excellent solution for environmental sustainability and energy efficiency. This review paper delves into the fundamentals of fuel cells, their characteristics, and their applications in the automotive realm, exploring their prospects in comparison to traditional technologies. Furthermore, it sheds light on the existing research and industrial developments in hydrogen and fuel cell technologies. Additionally, a comprehensive comparison is provided between various fuel cell cars that have already been commercialized, enabling readers to understand the current market landscape. The review also analyses the advantages and challenges associated with fuel cell technology, offering insights into its future development trajectory. Through this comprehensive exploration, readers can gain a deeper understanding of fuel cell technology and its potential in revolutionizing the automotive industry. [ABSTRACT FROM AUTHOR]

In 2 O 3 @ZnO nanotubes were fabricated using MIL-68@ZIF-8 as a template, and then fern-like In 2 O 3 @ZnO@Pd nanotubes with unique structures were synthesized by chemical reduction. The samples were thoroughly investigated to study their composition, morphology and structure. Hydrogen (H 2) sensitization characteristics of sensor of In 2 O 3 @ZnO@Pd nanotubes with different ZnO and Pd contents were tested at room temperature (RT). The In 2 O 3 @ZnO@Pd nanotube sensor with a palladium（Pd）content of 2.0 wt% exhibits a high response (R a /R g = 270) and fast response time (t res = 32 s) and recovery time (t rec = 116 s) to 10,000 ppm H 2 at RT, as well as excellent selectivity, behaving a response nearly six times that of interfering gases. The excellent hydrogen sensing performance indicates that the fern-like In 2 O 3 @ZnO@Pd nanocomposite has good application prospects and is an excellent hydrogen-sensitive material. In this paper, In 2 O 3 @ZnO nanotubes were prepared using nanoscale MIL-68@ZIF-8 as a template to enable further optimization of morphology with smaller scales. Fern-like In 2 O 3 @ZnO@Pd nanotubes with unique structures were then synthesized by doping noble metal Pd and chemical reduction. The H 2 sensing properties of fern-like In 2 O 3 @ZnO@Pd nanotubes to different concentrations of hydrogen were investigated by varying the contents of zinc oxide (ZnO) and Pd elements. The In3Zn–Pd 2 sample showed excellent sensitivity and selectivity to 10,000 ppm H 2 with a maximum response of 277.1 at RT, which was 6.6 times higher than pure In 2 O 3 @ZnO at the same temperature, and the response value was nearly six times that of the interfering gas. Moreover, the response/recovery time of the NT-Pd 2 samples was 32 and 116 s, respectively, which was substantially shorter than those of In 2 O 3 @ZnO at the same temperature (183 and 355s). [Display omitted] • Hydrogen gas sensor fabricated using fern-like In 2 O 3 @ZnO@Pd nanotubes. • The sensor detects hydrogen at room temperature providing a wider and safer range of applications. • The sensor has a high response value (277.1) and short response/recovery time (32s/116s) to hydrogen at room temperature. • The sensor has good selectivity and a response value of up to six times that of interfering gases. [ABSTRACT FROM AUTHOR]

This work assesses a chemical plant for the conversion of biogas into negative emission "emerald hydrogen" via electrified reforming and CO 2 separation. Electrification of the reformer allows for enhanced syngas production, compact reactor designs and flexible operation, thanks to the avoidance of combustion and heat transfer through pressure walls. The integration of the process with solar and wind power generation has been assessed by part-load process simulations and plant sizing and operation optimization through yearly simulations with hourly discretization. Different European locations with different wind and solar availabilities were assessed considering (i) short- and long-term cost scenarios for renewables and battery technologies and (ii) different plant size (from 390 to 3900 Nm3/h of biogas capacity). The overarching scope of the paper is to calculate the cost of the produced hydrogen and the economic value of flexibility for plants installed in different locations, under different cost scenarios. At design load, the assessed process consumes 17.7 kWh of electricity per kg H2 and retains 96% of the biogas chemical energy in the produced hydrogen. Additionally, 76% of the biogenic carbon is recovered as high-purity liquid CO 2 , achieving up to −9 kg CO2 /kg H2 negative emissions. When powered with 95% of renewable energy, hydrogen production cost ranges from 2.5 to 2.9 €/kg for a long-term REN cost scenario and large-scale flexible plant to 5.9–7.1 €/kg for a short-term REN cost scenario and small-scale inflexible plants. For small-scale plants, flexibility allows to reduce the hydrogen production cost by 11–16% with respect to the inflexible plant in the short-term renewables cost scenario and by 1–4% in the long-term cost scenario. For large-scale plants, the adoption of a flexible plant leads to a reduction of 17–23% of the hydrogen cost in the short-term scenario and of 6–22% in the long-term scenario. Operational flexibility of electrified reforming allows reducing the cost of negative-emission bio-hydrogen by 1–23%, depending on location and cost scenario. [Display omitted] • Process engineering study with off-design model. • Economic optimization of flexible process with PV, wind, BESS and gas storages. • 17.7 kWh/kg H2 of electric consumption and up to −9 kg CO2 /kg H2 negative emissions. • H 2 cost of 2.5–6.2 €/kg depending on location, REN cost scenario and plant capacity. • Flexibility reduces H 2 cost by 1–23% depending on location and REN cost scenario. [ABSTRACT FROM AUTHOR]

This study explores the potential of hydrogen gas turbine engines for sustainable aviation, with a particular focus on their development for low subsonic to transonic flight regimes. Hydrogen offers notable advantages, including zero CO 2 emissions and high energy density. However, its widespread adoption is prevented by significant challenges in production, infrastructure, storage, aircraft design, and combustion technology. The limited availability of green hydrogen – the global production totaled only 127 kt in 2023, with 76% produced in China - raises concerns about the feasibility of a rapid shift to hydrogen-powered general aviation. Despite numerous pledges for hydrogen adoption in the Western world, major aircraft manufacturers have primarily engaged in marketing activities rather than substantial product innovation. To date, the only hydrogen aircraft demonstrator from this century is the 2012 Boeing Phantom Eye, which utilized modified hydrogen internal combustion engines rather than a gas turbine engine. The only hydrogen aircraft demonstrator with a gas turbine engine was the 1988 hybrid Tupolev Tu-155 which coupled one hydrogen gas turbine engine to other two jet fuel engines. This paper evaluates the current state of hydrogen gas turbine technology, comparing its combustion characteristics with traditional jet fuels and examining various NOx emission control techniques. It also investigates the potential of micro-mix lean combustion and staged combustion to achieve efficient and low-emission hydrogen combustion in gas turbines. Given the more extensive experience with terrestrial gas turbines compared to their aeronautical counterparts, the review includes insights from terrestrial power generation applications. Additionally, it considers hythane - a blend of hydrogen and natural gas - as a transitional solution for significantly reducing CO 2 emissions while progressing towards net-zero targets. The review underscores the urgent need for advancements in green hydrogen production, technology, and infrastructure to overcome existing barriers and enable a more sustainable aviation future powered by hydrogen. Importantly, the review emphasizes the need to move beyond mere virtue signaling and make tangible progress toward a hydrogen economy. [ABSTRACT FROM AUTHOR]