Hydrogen Loading Research Articles

Voltage control of magnetic properties in GdxFe100-x films by hydrogen migration

Voltage control of magnetic properties is a promising path to realize low-power spintronic devices and meets the requirements for quicker information processing speed and ongoing scale reduction. Hydrogen migration induced by voltage gating has been demonstrated to modify the intrinsic magnetic properties of materials by affecting the exchange interaction, electron occupancy, and magnetoelastic effect. Herein, the magnetic properties of a ferrimagnetic Gd29Fe71 film in an all-solid-state multilayer device, which is constructed using a GdOx electrolyte, can be reversibly modulated by voltage-controlled hydrogen migration. Polar MOKE results indicate that hydrogen intercalation/deintercalation can modulate the Gd29Fe71 film's degree of compensation and control the dominant magnetic sublattice. Furthermore, the polarity of the polar MOKE curves can be reversibly switched. As with the increase in hydrogen loading, the compensation point in the Gd29Fe71 film is approached, the density of magnetic domain nucleation sites decreases, and the magnetic domain structures transform from labyrinth domains to uniform large area domains. At the same time, a strong perpendicular magnetic anisotropy is developed. This work shows a possible pathway for reversible control of magnetism in spintronic devices.

Mechanical loading effect on the hydrogen uptake of tempered martensite steel: Elastic strain effect vs. plastic strain effect

The effects of mechanical loading on hydrogen uptake were investigated by thermal desorption experiments under various combinations of hydrogen charging and loading conditions. The diffusible hydrogen content increased with increasing elastic and plastic strains. The increase in diffusible hydrogen content per elastic strain was larger than that per plastic strain.

Optimized Demand-Side Day-Ahead Generation Scheduling Model for a Wind-Photovoltaic-Energy Storage Hydrogen Production System.

This paper proposed an optimized day-ahead generation model involving hydrogen-load demand-side response, with an aim to make the operation of an integrated wind-photovoltaic-energy storage hydrogen production system more cost-efficient. Considering the time-of-use electricity pricing plan, demand for hydrogen load, and the intermittency of renewable energy, the model has the ambition to achieve minimum daily cost of operating a hydrogen production system. The model is power-balanced, fit for energy storage devices, and developed through adaptive simulated annealing particle swarm optimization. Analysis results showed that the proposed optimized scheduling model helped avoid the significant purchase of electric power at peak times and reduced the cost of running the hydrogen production system, ensuring that the daily hydrogen energy produced could meet the daily demand for the gas load. This justified how the model and its algorithm were correctly and efficiently applied.

Feasibility analysis of hydrogen production potential from rooftop solar power plant for industrial zones in Vietnam

Currently, global energy transformation and the promotion of renewable energy use are being taken care of to minimize the harm to the environment. However, the disadvantage of renewable energy is the random change, which leads to the regulation of grid operations, which is very difficult when the capacity of renewable energy sources accounts for a large proportion. The hydrogen production technology from wind and solar energy sources is one of the possible methods to minimize adverse impacts on the utility grid and serve the load demand of industrial zones. In this study, the photovoltaic (PV) hydrogen production potential for industrial zones in Vietnam is analyzed. The Homer was used to simulate and calculate power output. The results showed that the Hai Duong province has the lowest solar radiation, so the solar power output is 3600389 kWh/year, and the amount of hydrogen generated is less so it mainly serves the hydrogen load while the fuel cell can only generate very low amounts of electricity of about 4150 kWh/year for direct current (DC) load. The hybrid power systems in the typical industrial plant in Quang Nam province, Binh Thuan province, Can Tho city can generate about 17386 kg/year to 17422 kg/year to supply the operation of fuel cells based on the value of solar radiation of each province. The better the area with solar potential, the lower the net present cost (NPC), cost of energy (COE), and operation cost, so the economical and technical efficiency of the PV–Fuel cell hybrid power system will increase.

Multiple time-scale energy management strategy for a hydrogen-based multi-energy microgrid

With the technological advances in energy conversion and utilization of multiple forms of energy sources, hydrogen energy has attracted increasing attention. The hydrogen energy can be used to directly supply the hydrogen demand and generate both electricity and heat through fuel cell-based combined heat and power (FC-CHP) unit. This paper proposed a multiple time-scale energy management solution for a hydrogen-based multi-energy microgrid (MEMG) to supply electricity, hydrogen and heating loads aiming to minimize the MEMG operational cost with consideration of renewable energy generation and demand uncertainties. The proposed solution consists of day-ahead energy scheduling and model predictive control (MPC) based real-time energy dispatch in the presence of the electricity market. In the hydrogen-based MEMG, the electricity and hydrogen can be dispatched and utilized across multiple interconnected subsystems to improve the overall system energy utilization efficiency. The proposed solution is extensively assessed through simulation experiments compared with a benchmark solution. The numerical results confirm that the proposed solution outperforms the benchmark solution with the mean daily actual operational costs reduced by 37.08%.

In vitro and in vivo evaluation of surface functionalization of titanium with H2 O2 hydrothermal treatment and FGF-2.

The goals of the study were to investigate the effects on bone bioactivity of a titanium dioxide layer formed by hydrothermal oxidation of a titanium surface with hydrogen peroxide (H2 O2 ) and loading with fibroblast growth factor-2 (FGF-2) in vitro and in vivo. Ti-6Al-4V discs were hydrothermally oxidized with H2 O2 and then loaded with FGF-2. After cytotoxicity testing, Ti-6Al-4V mini-implants were subjected to the same treatment, and their osteogenic potential was evaluated histologically in a rat model. H2 O2 hydrothermal oxidation resulted in a dense porous network structure and hydrophilic changes, which improved retention of FGF-2. Morphologically, the cell density was higher, cell elongation was more pronounced, and the cell adhesion area was significantly higher in FGF-2-loaded cells than in those without FGF-2. In a cell proliferation assay using mouse osteoblast-like cells, absorbance tended to increase over time, especially in the FGF-2 group after 7 and 14 days, and in a bone differentiation assay based on ALP activity, there was a significant increase in the FGF-2 group after 14 days. In the rat model, H2 O2 hydrothermal oxidation and FGF-2 loading both resulted in more laminar bone tissue in the bone marrow around the mini-implant. These results suggest that titanium surface functionalization by H2 O2 hydrothermal oxidation and FGF-2 may promote initial cell adhesion, proliferation, and osteodifferentiation, and enhance bone bioactivity. These effects all contribute to early bonding of an implant with the surrounding bone.

Techno-economic optimization of PV system for hydrogen production and electric vehicle charging stations under five different climatic conditions in India

India is one of the most populous countries in the world, and this has implications for its energy consumption. The country's electricity generation and road transport are mostly dominated by fossil fuels. As such, this study assessed the techno-economics and environmental impact of a solar photovoltaic power plant for both electricity and hydrogen production at five different locations in India (i.e., Chennai, Indore, Kolkata, Ludhiana, and Mumbai). The hydrogen load represents a refueling station for 20 hydrogen fuel cell vehicles with a tank capacity of 5 kg for each location. According to the results, the highest hydrogen production occurred at Kolkata with 82,054 kg/year, followed by Chennai with 79,030 kg/year. Ludhiana, Indore, and Mumbai followed with 78,524 kg/year, 76,935 kg/year and 74,510 kg/year, respectively. The levelized cost of energy (LCOE) for all locations ranges between 0.41 and 0.48 $/kWh. Mumbai recorded the least LCOH of 3.00 $/kg. The total electricity that could be generated from all five cities combined was found to be about 25 GWh per annum, which translates to an avoidable emission of 20,744.07 metric tons of CO2e. Replacing the gasoline that could be used to fuel the vehicles with hydrogen will result in a CO2 reduction potential of 2452.969 tons per annum in India. The findings indicate that the various optimized configurations at the various locations could be economically viable to be developed.

SolvX: Solvothermal conversion of mixed waste plastics in supercritical toluene in presence of Pd/C catalyst

As the world's ability to cope with the fast-rising output of disposable plastic products is limited, plastic pollution has emerged as one of the most important environmental challenges. Catalytic solvothermal conversion (SolvX) could potentially utilize mixed waste plastics (MWPs) for sustainable fuels and chemical production. In this study, the effect of SolvX reaction time (1 – 5 h), Pd/C catalyst loading (0 – 10 wt%), and hydrogen loading (0–75 bar) on MWPs were investigated using supercritical toluene as solvent at temperature 350 °C. Four major waste plastics including low-density polyethylene (#4), polypropylene (#5), polystyrene (#6), and polyurethane (#7) were used as feedstock for this study. Along with SolvX conversion, the liquid products (crude oils) were characterized for elemental composition changes using ultimate analysis, boiling point distribution via thermogravimetric analysis, functional groups alteration using Fourier transform infrared spectroscopy, and product identification via gas chromatography-mass spectrometry. The results showed that the addition of catalyst and hydrogen have positive effects on the SolvX conversion. According to the elemental analysis, the SolvX crude oils' higher heating values (HHV) range from 32 to 38 MJ/Kg. The range of boiling points demonstrates that Pd/C increases the formation of lighter hydrocarbons. Additionally, a proposed catalytic SolvX reaction mechanism shows that the aromaticity raised with the increment of residence time and Pd/C enhances hydrodenitrogenation and deoxygenation at higher hydrogen loading.

Solvothermal liquefaction of waste polyurethane using supercritical toluene in presence of noble metal catalysts

AbstractSolvothermal liquefaction (STL) is a thermochemical conversion method that uses sub‐or supercritical solvents to convert waste plastics like waste polyurethane (PU) into value‐added chemicals. This study aimed to evaluate catalytic STL utilizing toluene as a solvent for depolymerization of waste PU into valuable products. The effect of catalyst type (Pt/C, Pd/C, and Ru/C), catalyst loading (0–10 wt%), STL reaction temperature (330°C, 350°C, and 370°C), STL residence time (1, 3, and 5 h), and hydrogen loading (25, 50, and 75 bar) on STL conversion were studied. Results showed that Ru/C outperformed Pt/C and Pd/C and the STL conversion reached to as high as 87.2%. The concentrations of nitrogen‐containing components like aniline and p‐aminotoluene were increased with the increase of Ru/C loading and STL reaction temperature.

Multi-optimal design and dispatch for a grid-connected solar photovoltaic-based multigeneration energy system through economic, energy and environmental assessment

Solar photovoltaic-based multigeneration energy systems (SPVMES) which can use the excess energy of photovoltaic (PV) systems for heating and hydrogen production to improve the self-consumption of solar PV, have gained wide attention as a promising solution for clean and efficient production. To reliably meet diverse energy demands, gird system is integrated into a SPVMES as a backup energy source. In this paper, a grid-connected SPVMES is established to meet the electricity, heating and hydrogen loads, including PV, electrolysis, solid oxide fuel cell, electric heater for small-scale centralized heating and energy storage devices for electricity, heating and hydrogen storage, respectively. The emphasis to focus on when designing and dispatching the SPVMES lies in system performance evaluation. The innovation of this paper is to design and dispatch such a grid-connected SPVMES in a preliminary design stage through economic, energy and environmental assessment by considering cost of energy (COE), energy rate (ER) and renewable fraction (RF). Simultaneously, to explore which single objective/multi-objective optimization has better performance in comprehensive system evaluation, four different scenarios named COE optimization, RF optimization, ER optimization and multi-objective optimization are analyzed and compared. The specific application processes of component sizing and system dispatching with different optimization objectives are presented in detail. The results show that the proposed system has the COE of 0.0343$ in COE optimization scenario, the ER of 0.9128 in ER optimization scenario and the RF of 0.8811 in RF optimization scenario, which shows its significant potential in economic, energy efficiency and environmental performance. By comprehensively scoring the four optimization scenarios, it can be found that the multi-objective optimization scenario has better performance in system performance evaluation compared to the other three single objective optimization scenarios. Additionally, the multi-objective optimization could balance the tradeoff of COE, RF and ER and compromise the results of the single objective optimization scenarios. Potentially, sensitivity analysis is conducted to point out the effect of discharging depth of battery, PV subsidy, linear increasement of loads and seasonality effect on system performances.

The effect of structural disorder on the hydrogen loading into the graphene/nickel interface

Hybrid materials composed by porous Ni foams coated by graphene appear appealing architectures to be applied in the field of hydrogen storage, where, due to the high surface-to-volume ratio of both components, are expected to be much more performant than their flat counterparts. In order to explore this possibility, in this study we have grown single layer graphene on nickel foams by chemical vapour deposition in ultra-high vacuum and have investigated the interaction with H atoms as a function of the temperature. By using high resolution C1s core level spectroscopy we found that nearly half of the graphene layer interacts with the support almost as strongly as with the flat ordered Ni substrate, whereas the other half is nearly free standing. Such dual electronic and structural coupling drives the hydrogenation of the graphene/foam interface. By using thermal programmed desorption combined with x-ray photoelectron spectroscopy we found that in the weakly interacting graphene regions, even at very low temperatures, H atoms easily intercalate below graphene, and enter in the bulk of the foam, from where they start to desorb around 180 K. This behaviour mimics what happens when dosing H atoms on the bare Ni foam. On the contrary, H intercalation below the strongly interacting graphene regions occurs only for temperatures around and above 200 K. The thermal desorption curves demonstrated that the presence of the graphene layer does not reduce the effectiveness of H loading in the bulk of the foam. On the other hand, it does not even increase significantly the stored amount with respect to the uncoated support, but contributes to stabilizing the stored hydrogen. Although the fundamental aspects of graphene/foam hydrogenation were here investigated in a regime far below the saturation of the bulk absorption, these measurements can be the starting point for further investigations aimed at establishing the ultimate storage capability of these hybrid nanostructured tanks.

Integrated sizing and scheduling of an off-grid integrated energy system for an isolated renewable energy hydrogen refueling station

When designing an isolated renewable energy hydrogen refueling station (HRS), it is important to consider the electrical, heating and cooling demands of the supporting building as it is crucial for maintaining the stable HRS operation. Therefore, this paper proposed a new structure of off-grid integrated energy system (OIES) for an isolated renewable energy HRS, which can meet the hydrogen load of the market and the three kinds of loads of the supporting building. The OIES in question consists of wind generators, PV panels, batteries, electrolyzers, heat storage tanks, hydrogen tanks, and absorption chillers. A mixed integer quadratic constrained programming (MIQCP) model of the OIES is built based on the minimization of the total life cycle cost (TLCC). It is built to obtain the optimal solution for sizing and the equipment units’ scheduling strategy. To accord with the actual situation, the electrical, heating, and cooling loads of the supporting building in the simulation are obtained by the EnergyPlus software. Furthermore, the ‘community’ hydrogen demand is obtained by the HOMER software. The results indicate that the proposed structure meets a wide array of energy demands and is more sensible solution when compared to other configurations with one component less. In addition, sensitivity analyses of the influence of economic data, meteorological data, and hydrogen load on TLCC are performed. These results show that the capital and replacement cost of the PV panels are the major economic factors influencing the TLCC. They also confirm that the PV is the system’s main component due to a high correlation between the hourly hydrogen demand per year and the hourly solar radiation per year. Lastly, the effects of meteorological data and hydrogen load are also quantitatively analyzed.

A scenario-based stochastic model for day-ahead energy management of a multi-carrier microgrid considering uncertainty of electric vehicles

This paper presents a scenario-based stochastic management algorithm to deal with scheduling the optimal operation of a multi-carrier microgrid (MG). The proposed framework of the multi-carrier MG comprises of wind turbine (WT), photovoltaic (PV) panel, fuel cell (FC), microturbine (MT), boiler, combined heat and power (CHP) unit, electrical load, thermal load, hydrogen load, electrical energy storage, H2 storage, and thermal storage. To cope with the uncertainties arisen by the renewable resources, electricity price, electrical load, and electric vehicle (EV), we proposed a scenario-based approach to model the uncertain parameters (wind speed, solar irradiance, electricity price, electrical load, EV arrival time, EV departure time, and EV traveled distance). The proposed algorithm initially estimates the uncertain parameters through fitting a probability distribution function (PDF) with the time series of historical uncertain parameters. Then, the scenario generation and reduction approach is applied to find the finite scenarios according to the fitted PDFs. The stochastic management algorithm is formulated as a cost minimization problem, where the demand response (DR) program is embedded in the formulation. The proposed framework is tested on a sample multi-carrier MG for two cases, namely, the application of stochastic energy management for a Multi-carrier MG with and without DR. Also, we perform a comparative study to show the benefits of the stochastic management algorithm along with a deterministic approach.

Study of γ-valerolactone production from hydrogenation of levulinic acid over nanostructured Pt-hydrotalcite catalysts at low temperature

Hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is an important reaction in biomass upgradation to produce value-added chemicals. In this work, we have successfully prepared well dispersed nanocrystalline Pt-HT catalyst and found that this catalyst is showing excellent performance for the levulinic acid hydrogenation to produce GVL. Pt-HT catalyst showed ∼100% conversion with ∼100% selectivity of GVL at low temperature with external hydrogen in a batch reactor in aqueous medium. Different reaction parameters like hydrogen pressure, temperature, reaction time and loading of Pt were studied in detail. The catalyst was successfully reused up to 7 times without any loss of the catalytic activity. The catalyst was characterized by XRD, SEM, HR-TEM, BET, XPS, TPR, TPD and DFT study. It was observed that the highly dispersed metallic Pt is the active species to achieve the good conversion and selectivity of GVL even at room temperature and the catalyst is showing very high stability and recyclability during hydrogenation, making it very promising truly heterogeneous catalyst for practical γ-valerolactone production via hydrogenation of levulinic acid.

Two-Stage Energy Management Strategies of Sustainable Wind-PV-Hydrogen-Storage Microgrid Based on Receding Horizon Optimization

Hydrogen and renewable electricity-based microgrid is considered to be a promising way to reduce carbon emissions, promote the consumption of renewable energies and improve the sustainability of the energy system. In view of the fact that the existing day-ahead optimal operation model ignores the uncertainties and fluctuations of renewable energies and loads, a two-stage energy management model is proposed for the sustainable wind-PV-hydrogen-storage microgrid based on receding horizon optimization to eliminate the adverse effects of their uncertainties and fluctuations. In the first stage, the day-ahead optimization is performed based on the predicted outpower of WT and PV, the predicted demands of power and hydrogen loads. In the second stage, the intra-day optimization is performed based on the actual data to trace the day-ahead operation schemes. Since the intra-day optimization can update the operation scheme based on the latest data of renewable energies and loads, the proposed two-stage management model is effective in eliminating the uncertain factors and maintaining the stability of the whole system. Simulations show that the proposed two-stage energy management model is robust and effective in coordinating the operation of the wind-PV-hydrogen-storage microgrid and eliminating the uncertainties and fluctuations of WT, PV and loads. In addition, the battery storage can reduce the operation cost, alleviate the fluctuations of the exchanged power with the power grid and improve the performance of the energy management model.

Optimization of hydrogen-producing sustainable island microgrids

Hydrogen-based microgrids are receiving attention as critical pathways are being charted for the decarbonization of our thermal, transport, and power grids. In this article, clean, cost-effective, and reliable hybrid microgrid designs are developed to satisfy hydrogen and electricity loads in three energy-stressed islands of Eastern Canada, namely Pelee, Wolfe, and Saint Pierre. The design iterations incorporate elements of solar, wind, fuel cells, Hydrogen, and electricity storage. Real-time field irradiation, wind speed, ambient temperature, and load data over 8760 h have been used to drive the designs. Although the anticipated inflation rate in Newfoundland is higher than in Ontario, the lowest net present cost (NPC) of the hybrid solution is found in Saint Pierre Island. The hydrogen cost, in this case, is $7.5/kgH 2 and $15.8/kgH 2 lower than that of Pelee and Wolfe islands, respectively. The maximum H 2 tank capacity (≥680 kgH 2 ) on Pelee Island is 3000 h/yr and 1000 h/yr lower than optimal cases in Saint Pierre and Wolf Islands, respectively. LCOE is more sensitive to market changes in fuel cell costs than other components. The highest LCOE reduction (∼63%) is observed when the optimal case in Pelee Island increases its lifetime. Analyzing the volatility in resource assessment indicates that predicting the energy cost over a short-term project is challenging. The salvage share in the long-term project is more than that of the short-term, indicating that the long-term project can be more cost-effective taken overall. • Feasibility analysis of renewables in refuelling station and residential buildings of Pelee, Wolfe, and Saint Pierre Islands. • Simultaneous production of Hydrogen and electricity production via renewables is economically and technically feasible. • The lowest value of energy and Hydrogen cost are obtained in Saint Pierre Island. • The energy cost over a short-term project is challenging and less profitable than a long-term project.

Resonant neutron reflectometry for hydrogen detection

The detection and quantification of hydrogen is becoming increasingly important in research on electronic materials and devices, following the identification of the hydrogen content as a potent control parameter for the electronic properties. However, establishing quantitative correlations between the hydrogen content and the physical properties of solids remains a formidable challenge. Here we report neutron reflectometry experiments on 50 nm thick niobium films during hydrogen loading, and show that the momentum-space position of a prominent waveguide resonance allows tracking of the absolute hydrogen content with an accuracy of about one atomic percent on a timescale of less than a minute. Resonance-enhanced neutron reflectometry thus allows fast, direct, and non-destructive measurements of the hydrogen concentration in thin-film structures, with sensitivity high enough for real-time in-situ studies.

Thermodynamics of Hydrogen in thin films and mathematical calculations

Abstract: The behavior of Mg/Pd and Mg/Cr thin films, exposed to a hydrogen pressure, was investigated. Two experimental methods for determining the thermodynamics of hydrogen in thin films have been presented in this paper. The first method based on the dependency of the resistance variation rate of the sample on hydrogen pressure and used for determining plateau pressure. The second approach is relying on the on hydrogen uptake during the hydrogen loading process. The bulk data for comparison have been calculated using mathematical calculations.

Graphene based electrodes for hydrogen fuel cells: A comprehensive review

Today, the world is facing a great challenge to keep the environment as much clean and green as possible. Hydrogen fuel cells are envisaged for greener environment minimizing dependence on conventional natural energy resources. In this perspective, graphene-enhanced electrode materials can be the best bet for hydrogen storage for improving the performance of fuel cell applications.Graphene is fundamentally composed of single layer of graphite that consists of sp2-bonded carbon atoms forming a honeycomb or hexagonal type of lattice structure. Graphene provides a potential solid matrix for high capacity hydrogen storage. Loading of atomic hydrogen on graphene produces hydrogenated graphene modifying phonon and electronic properties. Multilayered graphene is more suitable than single-layered graphene for hydrogenation. On loading with hydrogen atoms, sp3 C–H bonds are developed on the basal plane of single-layer graphene. Hydrogen can be adsorbed on graphene either by physisorption (employing weak van der Waals forces) or by chemisorption (by chemical bonding i.e. ionic or covalent bonds with carbon atoms). In this work, a comprehensive review of the prominent reported works is presented on graphene enhanced electrode materials for hydrogen fuel cell applications. Various configurational attachment sites over graphene are discussed from a theoretical standpoint. Moreover, the review article has attempted to cover broader work on graphene enhanced electrode materials by presenting year-wise critical description of published research from 2016 to 2021.

Dislocations, texture and stress development in hydrogen-cycled Pd thin films: An in-situ X-ray diffraction study

For Pd thin films, microstructural changes involved during hydrogen cycling provide the information needed to predict and optimize the film's mechanical strength. In this paper, a systematic study of the morphology, microstructure, texture, and stress has been performed on Pd thin films during hydrogen loading and deloading cycles at room temperature. Pd thin films of similar morphology were prepared by magnetron sputtering on substrates of different compliances, i.e., Si-oxide, Titanium (Ti) and Polyimide (PI). The evolution of the morphology, grain-orientation distribution (texture), state of stress, and dislocation densities are analyzed for each of the film substrate types for 20 hydrogen loading/deloading cycles. The lattice expansion and contraction caused by the transition from Pd to Pd-hydride and back result in a strong stress increase. This stress increase stabilizes after a few cycles by grain boundary motion that leads to a gradual enhancement of the (111) texture and changes in the dislocation density for Pd films that are strongly clamped on to an oxidized Si(100) wafer substrate with an intermediate layer (Ti or PI). For Pd on PI, the stress is also partly released by a crack-based (crack widening/growth/propagation) pathway. Pd films on Ti and PI do not buckle or blister after 20 hydrogen cycles. By providing a sufficiently compliant substrate the traditional problems of buckle-delamination of a film on a stiff substrate are mitigated. • Pd thin films: microstructure and mechanical strength during hydrogen cycling studied. • Cyclic deformation resulted in irreversible texture changes − sharpening of (111)-fiber texture. • An open morphology restricts internal stress from amplifying during hydrogen uptake. • All Pd films contain similar kinds of defects, that differ only by their concentration. • The flexible PI inter-layer provides enhanced adhesive support, preventing strain localization and film delamination.