Hydrogen Loading Research Articles

Cooperative Operation of Power and Hydrogen Energy Systems With HFCV Demand Response

Hydrogen has shown great potential in the renewable power integration and urban mobility decarbonization like hydrogen fuel cell vehicles (HFCVs). The HFCV refueling as an essential hydrogen load is of great flexibility. Considering the HFCV demand response (DR), this article studies the integrated electric power and hydrogen system (IPHS) operation. First, the HFCV refueling load model is formulated with its routing on the transportation network considered. Second, the optimal IPHS operation model is developed in which the electric power operation, tube-trailer based hydrogen delivery and HFCV refueling are coordinated. Third, a Lagrangian relaxation based method is developed to solve the proposed model efficiently, which corresponds to a price-based DR mechanism for HFCVs. Compared with existing works on IPHS, the influence of transportation networks is delicately analyzed on both HFCV refueling and hydrogen delivery. The case studies have proven the effectiveness of the proposed method and demonstrated that the overall operation cost is decreased via the proper guidance of HFCV refueling. The HFCV DR shows great potential in exploring the synergy of energy and transportation systems.

Robust optimal dispatch of integrated energy system considering with coupled wind and hydrogen system

Hydrogen production from renewable energy will become one of the important features of the integrated energy system in the future. By considering the coupled wind and hydrogen system, it can not only take the advantages of fast power regulation of hydrogen energy, but improve the economy of wind and hydrogen system. In view of the high volatility of the wind power, this paper proposes a robust optimal scheduling model for integrated energy system considering with coupled wind and hydrogen system. Firstly, it establishes a comprehensive energy system model with wind and hydrogen system, forming an efficient electric-gas-electric energy closed-loop flow model with fuel cells. Then, based on improved multi-interval uncertainty sets, the model of wind turbines, electrical load and hydrogen load are described respectively, which can reduce the conservatism compared with the traditional robust optimization. And the two-stage robust optimal scheduling model is established and it can be solved by adopting Column and Constraint Generation method (C&CG). Finally, an example is given to verify the advantages of the proposed method.

Determination of hydrogen loading in the carrier system diphenylmethane/dicyclohexylmethane by depolarized Raman spectroscopy

During the processes of hydrogenation or dehydrogenation of liquid organic hydrogen carriers (LOHCs), knowledge of the current degree of hydrogenation (DoH) is often essential. The present study shows that depolarized Raman spectroscopy allows the accurate determination of the DoH of the model LOHC system diphenylmethane (H0-DPM)/dicyclohexylmethane (H12-DPM) at temperatures up to 573 K. Using two independent experimental setups and binary mixtures of H0- and H12-DPM, a temperature-independent calibration factor could be obtained by analyzing Raman bands characteristic for the aromatic and aliphatic carbon rings. The successful transfer of the calibration to technical mixtures is validated by DoH measurements of samples from deliberately stopped hydrogenation reactions containing also the intermediate cyclohexylphenylmethane (H6-DPM) and of pure H6-DPM. Here, the average absolute deviation of the DoHs obtained by depolarized Raman spectroscopy from those measured analytically is 0.018, which demonstrates the applicability of the method at arbitrary and process-relevant temperatures.

E-Selective Manganese-Catalyzed Semihydrogenation of Alkynes with H2 Directly Employed or In Situ-Generated.

Selective semihydrogenation of alkynes with the Mn(I) alkyl catalyst fac-[Mn(dippe)(CO)3(CH2CH2CH3)] (dippe = 1,2-bis(di-iso-propylphosphino)ethane) as a precatalyst is described. The required hydrogen gas is either directly employed or in situ-generated upon alcoholysis of KBH4 with methanol. A series of aryl-aryl, aryl-alkyl, alkyl-alkyl, and terminal alkynes was readily hydrogenated to yield E-alkenes in good to excellent isolated yields. The reaction proceeds at 60 °C for directly employed hydrogen or at 60–90 °C with in situ-generated hydrogen and catalyst loadings of 0.5–2 mol %. The implemented protocol tolerates a variety of electron-donating and electron-withdrawing functional groups, including halides, phenols, nitriles, unprotected amines, and heterocycles. The reaction can be upscaled to the gram scale. Mechanistic investigations, including deuterium-labeling studies and density functional theory (DFT) calculations, were undertaken to provide a reasonable reaction mechanism, showing that initially formed Z-isomer undergoes fast isomerization to afford the thermodynamically more stable E-isomer.

Integrated performance optimization of a biomass-based hybrid hydrogen/thermal energy storage system for building and hydrogen vehicles

The increase of diversified energy demand, such as building and transportation fields, is bringing great challenges for energy supply. New energy vehicles, such as hydrogen vehicles, have drawn attention increasingly, in which hydrogen demand is usually close to buildings. To satisfy diversified energy demand and solve supply-demand mismatch, operation optimization of biomass-based hybrid hydrogen/thermal energy storage system for building and hydrogen vehicles is investigated, in which building and hydrogen vehicles loads are considered simultaneously. Two operation strategies (following the electricity demand with hydrogen load (FE-HL) and following the thermal demand with hydrogen load (FT-HL)) are proposed. Operation performance on weekday and weekend in different seasons under two operation strategies are compared. Researches indicate that system performance under FE-HL is much better than that of FT-HL. Under FE-HL strategy, primary energy consumption saving ratio, annual total expenditure reduction ratio and CO2 emission reduction ratio are 11.82%, 46.20% and 86.67%, respectively, and the above indicators are −12.11%, 27.83% and 65.72% under FT-HL strategy accordingly. Moreover, the system performances under two operation strategies show a reverse trend with the increase in hydrogen load. In general, this study provides an inspiring idea for supply-demand matching optimization between renewable integration system and building-hydrogen vehicles.

Quantification of the influence of the C, Cr and P contents on the permeability of hydrogen through Fe alloys

Ferritic-martensitic steels are candidate materials for blanket structural components of future thermonuclear fusion reactors. However, the tritium inventory that can be retained in different components of the reactor and its ability to migrate through the walls of any material may affect the correct operation of any fusion device. Therefore, the permeability of hydrogen isotopes through ferritic-martensitic steels, which depends on its metallurgical composition, becomes a key issue.The European Fusion Development Agreement (EFDA) supplied 9 Fe alloys with controlled chemical alloying element contents and microstructure. The main alloying elements were C, Cr and P and they appeared in various concentrations in the 9 alloys. They were experimentally analyzed by means of the gas evolution permeation technique with temperatures ranging from 423 K to 823 K and for high purity hydrogen loading pressures ranging from 5.0 × 102 Pa to 1.5 × 105 Pa. The transport regime turned out to be diffusive and it was studied in depth, so that the permeability of each alloy was characterized by an Arrhenius-type regression for the aforementioned temperature range.This work summarizes all the experimental measurements carried out for the permeability of hydrogen through the 9 alloys. It provides a quantification of the influence of the composition of the alloy on this transport parameter, posing different mathematical expressions for the variation of the permeability as a function of the contents of C, Cr and P.

RETRACTED: Risk-based design of hydrogen storage-based charging station for hydrogen and electric vehicles using downside risk constraint approach

• Optimal design of off-grid hydrogen and electric vehicles charging station. • Uncertainties of solar irradiance, electricity and hydrogen loads are considered. • A scenario-based stochastic optimization model is proposed to model uncertainties. • Downside risk constraints method is proposed to manage risk related to uncertainties. • Risk-averse state of the model is presented and compared to the risk-neutral state. This paper proposes an off-grid photovoltaic powered charging station for electric and hydrogen vehicles. The charging station simultaneously feeds hydrogen and electric vehicles during all hours of the day. Therefore, fuel cell and hydrogen storages systems are designated to the station to meet the demand during the inaccessibility of the solar system. Furthermore, a diesel generator is allocated to the system in case the severe impacts of uncertainties included in the energy profile of the solar system and the loads lead to power shortage. Downside risk constraints are integrated into the scenario-based stochastic programming model to handle the risks involved as a novel framework. The advantage of this approach to others is providing a scenario independent risk analysis by offering one specific expected cost for all scenarios. The risk-neutral mode of the project is contrasted with the risk-averse state to depict the efficiency of the framework. The comparisons confirm that a 4.31% increase in annualized cost leads to a remarkable reduction of risk-in-cost by 50%. As a result, the nominal capacity of the diesel generator increased from 78 to 109 kW in the risk-averse state. However, the installed capacity of the photovoltaic system remained constant for all risk levels at 1688 kW.

Discovering and Demonstrating a Novel High-Performing 2D-Patterned Electrode for Proton-Exchange Membrane Water Electrolysis Devices.

Proton-exchange membrane water electrolysis (PEMWE) produces hydrogen with high efficiency and purity but uses high-loading platinum-group metal (PGM) catalysts. Such concerns call for the development of novel electrode architectures to improve catalyst utilization and mass activity, thus promoting PEMWE cost competitiveness for large-scale implementation. In this study, we demonstrated, for the first time, a novel two-dimensional (2D)-patterned electrode with edge effects to address these challenges. The edge effect was induced by membrane properties, potential distribution, and counter electrode coverage and could be optimized by tuning the catalyst layer dimensions. To achieve identical PEMWE performance, the optimal pattern saved the 21% anode PGM catalyst compared with the conventional catalyst fully covered electrode. The PGM catalyst could be further reduced by 61% to boost mass activity with no significant performance loss. The results also indicated that the electrode uniformity in PEMWE cells might not be as critical as that in PEM fuel cells. The novel 2D-patterned electrode could effectively reduce PGM catalyst loading, accelerating affordable and large-scale production of hydrogen and other value-added chemicals via electrolysis.

For the Vacancies Formation in Palladium During Hydrogen Loading Using a Novel Quartz Balance

For the Vacancies Formation in Palladium During Hydrogen Loading Using a Novel Quartz Balance

In-situ observation of buckling behavior during electrochemical hydrogen loading in Sm-Fe magnetostrictive thin films using acoustic emission (AE)

In-situ observation of buckling behavior during electrochemical hydrogen loading in Sm-Fe magnetostrictive thin films using acoustic emission (AE)

In-Plane Strain Measurement in Composite Structures with Fiber Bragg Grating Written in Side-Hole Elliptical Core Optical Fiber.

In this paper, the application of a fiber Bragg grating written in a highly birefringent side-hole elliptical core optical fiber for two-axial strain measurement is presented. Hybrid optical fiber structures achieved by combining large side-holes and elliptical core result in a very high birefringence of 1 × 10−3 and thus high initial Bragg peak spectral separation of 1.16 nm, as well as a very high transverse force sensitivity, of up to 650 pm/(N/mm) or even −1150 pm/(N/mm), depending on the fiber orientation with respect to the applied force. Due to the ~22 %m/m GeO2 concentration in the core the fiber being highly photosensitive, which significantly simplifies FBG fabrication by UV illumination without the need for prior hydrogen loading, which worsens thermal stability. Finally, the developed FBGs written in the highly birefringent side-hole elliptical core optical fiber were embedded in the square composite plates and applied for strain measurements. Tests of two-directional four-point bending have shown usability of such FBG for two-axial in-plane strain measurement with a single FBG in iso-thermal conditions.

A combined optimization of the sizing and the energy management of an industrial multi-energy microgrid: Application to a harbour area

• Sizing and operation combined optimization is proposed for an industrial microgrid. • Multi-energy microgrid is studied, with electricity and hydrogen as energy vectors. • The proposed objective functions aim to maximize incomes while minimizing expenses. • Ways of valorisation are compared: self-consumption, electricity and hydrogen sale. • The sizing and economical results are sensitive to investment and price assumptions. The current evolution of technical and environmental regulations and the recent development of hydrogen mobility require technological breakthroughs in the industrial areas, such as in harbours. Thus, multi-energy microgrids integrating low-carbon energy sources, electrical and hydrogen loads and storage solutions have to be designed. To improve their economic viability, the microgrid components must be carefully sized and the energy must be distributed in the most cost-effective way at any time. So as to foster the expansion of multi-energy microgrids in industrial areas, we propose in this paper a two-level optimization for the energy management and the sizing, applied to an original multi-energy scenario considering electricity and hydrogen as energy vectors. The designed energy management optimization takes into account an objective of economic profitability and constraints related to the availability of the sources and storage solutions, their reliability and the costs. The sizing optimization aims to propose different solutions allowing the benefits to be maximized and the expenses to be minimized. One of the main contributions of the paper is to compare the possible ways of valorisation of the energy available in an industrial microgrid. The results show that the sale of hydrogen allows income to be increased, in addition to self-consumption and sale to the electrical grid, but the electrolyzer involves high investments costs. Finally, a sensitivity analysis is presented and shows that the investment costs of electrolyzer and battery and the hydrogen selling price are key points in the optimal design.

Optimal design and techno-economic analysis of a hybrid renewable energy system for off-grid power supply and hydrogen production: A case study of West China

Reliable and sustainable energy supply is essential for the development of remote rural areas, especially in the context of stringent carbon emission reduction target. This study aims to demonstrate the techno-economic feasibility of a stand-alone hybrid renewable energy system (HRES) to satisfy the electric and hydrogen load for remote rural communities, where a case study of a village in West China is presented. By performing simulation and optimization, the most cost-competitive system configuration is identified, the net present cost (NPC), cost of energy (COE) and cost of hydrogen (COH) of which are $1.26M, $0.162/kWh and $12.5/kg, respectively. Compared with grid extension, the proposed system is more economical with a breakeven grid extension distance (BGED) of 16.15 km, and less carbon footprint with CO2 emission avoidance of around 375.44 t/year. In addition, sensitivity analysis on annual average hydrogen load growth and system capacity shortfall friction have been performed. The results indicated that the implementation of a hybrid power system can be a reliable and economic viable solution for remote rural electrification and decarbonizing local transport sector, whilst social and environmental benefits are also achieved.

Tuning the stress state in Nb-thin films by lateral size confinement

For 5 nm thin Nb films adhered to a rigid substrate, hydrogen absorption leads to ultrahigh mechanical stress of about -8 GPa. This is related to a purely elastic behaviour. The high mechanical stress destabilizes phases and even suppresses conventional two-phase regions known for the Nb-H bulk system. These unique thin film properties can be preserved to thicker films, by lateral confinement. Nb-Fe films provide a laterally confined columnar domain structure of well-separated α-Nb(Fe) and μ-FeNb phases. While the α-Nb(Fe) absorbs hydrogen at low chemical potentials, the μ-FeNb phase does not, separating the two phases into a hydrogen active and a hydrogen passive one. The behaviour of 75 nm Nb-Fe films was studied by in situ mechanical stress measurements, in situ x-ray diffraction and transmission electron microscopy. With increasing Fe-content, Nb-Fe films show a strong increase in the yield stress upon hydrogen absorption. This allows for an extended elastic range and high maximum stress values of -4.6 GPa, for 75 nm Nb-Fe films. X-ray diffraction pattern collected upon hydrogen loading of Nb-Fe films show peak shifts and intermediate peak broadening. This indicates the presence of a two-phase region and preservation of the lattice coherency between the α-Nb(Fe)-H phase and the hydride phase. Peak shifts indicate a reduced vertical expansion of the hydrogen absorbing α-Nb(Fe) lattice. This is attributed to the presence of the µ-FeNb phase. FEM simulations on Nb-Fe-H films confirm reduced overall expansions and lateral stresses, when compared to pure Nb-H films. High vertical stresses arise upon H-loading due to the link between the two Nb-Fe phases. These stresses are tensile for µ-FeNb and compressive for the α-Nb(Fe) domains and also reach values of several GPa. Conservation of the exceptional thin film properties to thicker films by lateral confinement is suggested to be a powerful strategy for many different applications like sensor technologies or energy storage.

Optimization control of hydrogen engine ignition system based on ACO-BP

With the development of new energy, hydrogen fuel engines have become a research boom in the automotive field. But there are abnormal problems such as backfire and pre-ignition during the combustion of hydrogen engines. This paper is based on the Ant Colony Optimization-Back Propagation (ACO-BP) algorithm to study the influence of different speed and load conditions on the ignition advance angle, so as to optimize the control of the hydrogen engine. The experimental system is established on a hydrogen engine converted from a 492Q gasoline engine. The prediction of the optimal ignition advance angle was obtained through experiments, and the optimal ignition MAP diagram of the hydrogen engine is constructed. The optimal ignition advance angle under different working conditions can effectively avoid the occurrence of hydrogen engine pre-ignition. The accuracy reaches 0.0018209 when the training reaches 14 times, the fitness between the actual value and the predicted value of ACO-BP training is 0.99921, the verification accuracy reaches 0.99913, and the test accuracy reaches 0.99932. Compared with the three optimization methods, the convergence speed and error accuracy of ACO-BP are significantly better than the BP neural networks and Genetic Algorithm-Back Propagation (GA-BP). This method realized the model of the nonlinear mapping model from hydrogen engine speed and load to optimal ignition advance angle, which is of great significance for solving the problem of abnormal combustion in hydrogen engine.

The effects of hydrogen-induced lattice distortion and Nb-D formation on its permeation through niobium

Abnormal permeation behavior of hydrogen through niobium has been investigated in this paper, i.e. the permeation flux saturated with long-term decrease after reaching a maximum. The diffusivity and permeability have been deduced from the decay edge of permeation transient. Three kinds of polycrystalline niobium foils with different annealing temperature have been compared, to verify the effect of defects and grain properties on the permeability and diffusivity. In the temperature range of (773–1023) K, the heat treatment along with the permeation cycles could either reduce or increase the permeability and diffusivity depending sensitively on temperature and showing a temperature threshold around 950 K. The permeation flux is proportional to square root of pressure, revealing that the abnormal permeation was still bulk diffusion-limited. The diffusivity gradually decreased with permeation cycles, and became more and more sensitive to pressure. The niobium foil expanded macroscopically along the gradient of hydrogen concentration, which reveals the strong and unrecoverable lattice distortion in this temperature and pressure range. The X-ray diffraction studies showed that splitting of all the Nb peaks and shifting of Nb-D peaks along with hydrogen loadings. The phase transition was expected to eliminate the lattice strain during hydrogen loading and which in turn acted as a diffusion barrier.

Ab Initio Hydrogen Dynamics and the Morphology of Voids in Amorphous Silicon

This paper presents an $ab$ $initio$ study of hydrogen dynamics inside nanometer-size voids in $a$-Si within the framework of the density-functional theory for a varying hydrogen load of 10 to 30 H atoms/void at the low and high temperature of 400 K and 700 K, respectively. Using the local density approximation and its generalized-gradient counterpart, the dynamics of hydrogen atoms inside the voids are examined with an emphasis on the diffusion of H atoms/molecules, and the resulting nanostructural changes of the void surfaces. The results from simulations suggest that the microstructure of the hydrogen distribution on the void surfaces and the morphology of the voids are characterized by the presence of a significant number of monohydride Si-H bonds, along with a few dihydride Si-H$_2$ configurations. The study also reveals that a considerable number of (about 10--45 at.%) total H atoms inside voids can appear as H$_2$ molecules for a hydrogen load of 10--30 H atoms/void. The approximate shape of the voids is addressed from a knowledge of the positions of the void-surface atoms using the convex-hull approximation and the Gaussian broadening of the pseudo-atomic surfaces of Si and H atoms.

Synergistic Effect of FeNi Bimetallic Clusters for the Catalytic of Hydrogen Dissociation and Desorption: A Density Functional Theory Study

Cognition to the metal-metal interactions is of vital importance for the catalytic process and would help exploring novel catalysts. In the present study, the model system of FexNiy (x + y = 6) bimetallic clusters was utilized to study how metal-metal interactions influence the catalytic performance. The formation energies of different FeNi clusters, the hydrogen chemisorption energies together with the maximum hydrogen capacity and the saturated hydrogen atoms desorption energies were calculated. Bimetallic clusters exhibit a superior performance than pure clusters. Especially, Fe2Ni4 cluster has the highest hydrogen loading capacity, the most facile hydrogen molecule dissociation activation energy barrier and the lowest hydrogen atom desorption energy, suggesting that it is easier to dissociate H2 and release the H atoms. As a consequence, by adjusting appropriate metal/metal ratios, it is possible to design bimetallic catalysts with excellent catalytic performance.

Fingerprinting diverse nanoporous materials for optimal hydrogen storage conditions using meta-learning.

Adsorptive hydrogen storage is a desirable technology for fuel cell vehicles, and efficiently identifying the optimal storage temperature requires modeling hydrogen loading as a continuous function of pressure and temperature. Using data obtained from high-throughput Monte Carlo simulations for zeolites, metal-organic frameworks, and hyper-cross-linked polymers, we develop a meta-learning model that jointly predicts the adsorption loading for multiple materials over wide ranges of pressure and temperature. Meta-learning gives higher accuracy and improved generalization compared to fitting a model separately to each material and allows us to identify the optimal hydrogen storage temperature with the highest working capacity for a given pressure difference. Materials with high optimal temperatures are found in close proximity in the fingerprint space and exhibit high isosteric heats of adsorption. Our method and results provide new guidelines toward the design of hydrogen storage materials and a new route to incorporate machine learning into high-throughput materials discovery.

Business model and planning approach for hydrogen energy systems at three application scenarios

Green hydrogen is used as fuel or raw material in power systems, transportation, and industry, which is expected to curb carbon emissions at the root. First, a unified energy system consisting of clean power generation systems, hydrogen energy systems (HESs), and transmission systems was proposed, and the characteristics of hydrogen load in different fields are analyzed. Possible business models for HESs in industry and transportation are then presented, cost and benefit functions for stakeholders of HES were created, and a business model with multi-party participation was modeled as a multi-objective optimization model. In a power system, the business model of combining two operating modes for hydrogen storage was proposed at the power generation side as well. Finally, three HESs were designed for a chemical plant with a hydrogen demand of 1000 Nm3/h, a hydrogen refueling station with a daily hydrogen load of 600 kg, and a 100% clean power generation system, respectively. The results of the case study show that one or more feasible business models (i.e., all stakeholders are profitable) can be found in both industrial and transportation by the HES planning approach proposed, while the internal rate of return of HES installed on the generation side is less than 5% due to high investment cost at this stage and low utilization rate; nonetheless, the profitable strategies are shown by 3D graphics.