China, People’s Republic
Hydrogen Production by Fluidized Bed Reactors: A Quantitative Perspective Using the Supervised Machine Learning Approach
Jul 2021
Publication
The current hydrogen generation technologies especially biomass gasification using fluidized bed reactors (FBRs) were rigorously reviewed. There are involute operational parameters in a fluidized bed gasifier that determine the anticipated outcomes for hydrogen production purposes. However limited reviews are present that link these parametric conditions with the corresponding performances based on experimental data collection. Using the constructed artificial neural networks (ANNs) as the supervised machine learning algorithm for data training the operational parameters from 52 literature reports were utilized to perform both the qualitative and quantitative assessments of the performance such as the hydrogen yield (HY) hydrogen content (HC) and carbon conversion efficiency (CCE). Seven types of operational parameters including the steam-to-biomass ratio (SBR) equivalent ratio (ER) temperature particle size of the feedstock residence time lower heating value (LHV) and carbon content (CC) were closely investigated. Six binary parameters have been identified to be statistically significant to the performance parameters (hydrogen yield (HY)) hydrogen content (HC) and carbon conversion efficiency (CCE) by analysis of variance (ANOVA). The optimal operational conditions derived from the machine leaning were recommended according to the needs of the outcomes. This review may provide helpful insights for researchers to comprehensively consider the operational conditions in order to achieve high hydrogen production using fluidized bed reactors during biomass gasification.
Nickel Sulfides Supported by Carbon Spheres as Efficient Catalysts for Hydrogen Evolution Reaction
Jun 2021
Publication
Ni3S2 and NiS supported on carbon spheres are successfully synthesized by a facile hydrothermal method. And then a series of physical characterizations included XRD (X-ray diffraction) EDS (energy dispersive spectroscopy) FESEM (field emission scanning electron microscopy) and XPS (X-ray photo-electron spectroscopy) were used to analyze the samples. XRD was used to confirm that NiNi3S2 S2 and NiS were successfully fabricated. FESEM indicated that Ni3S2 and NiS disperse well on carbon spheres. Electrochemical tests showed that nickel sulfides supported by carbon spheres exhibited excellent hydrogen evolution performance. The excellent catalytic activity is attributed to the synergistic effect of carbon spheres and transition metal sulfides of which the carbon spheres act to enhance the electrical conductivity and the dispersion of Ni3S2 and NiS thus providing more active sites for the hydrogen evolution reaction.
Stress Corrosion Behavior of AM50Gd Magnesium Alloy in Different Environments
May 2019
Publication
A new type of high strength corrosion-resistant magnesium alloy was prepared by adding 1% rare earth Gd to AM50 and then treated with hot extrusion method. The stress corrosion properties of the new materials in air pure water 0.5 mol/L NaCl and 0.5 mol/L Na2SO4 solution were studied by the slow strain rate tensile (SSRT) test in situ open circuit potential test Tafel curve test stereomicroscope SEM and EDS. The results showed the following. The stress corrosion sensitivity of the material in different environments was Na2SO4> NaCl > distilled water > air. According to the Tafel curves measured at 0 and 100 MPa the corrosion voltage decreased little and the corrosion current density increased rapidly under 100 Pa. This was because the film of the corrosion product ruptured to form a large cathode and a small anode which resulted in a large instantaneous corrosion current. The mechanism of hydrogen embrittlement and anodic dissolution together affected the stress corrosion behavior of the alloy. In distilled water hydrogen embrittlement played a major role while in NaCl and Na2SO4solution hydrogen embrittlement and anodic dissolution were both affected. The direct reason of the stress corrosion crack (SCC) samples’ failure was the cracks expanding rapidly at the bottom of pit which was caused by corrosion.
Numerical Simulation of Solid Oxide Fuel Cells Comparing Different Electrochemical Kinetics
Mar 2021
Publication
Solid oxide fuel cells (SOFCs) produce electricity with high electrical efficiency and fuel flexibility without pollution for example CO2 NOx SOx and particles. Still numerous issues hindered the large‐scale commercialization of fuel cell at a large scale such as fuel storage mechanical failure catalytic degradation electrode poisoning from fuel and air for example lifetime in relation to cost. Computational fluid dynamics (CFD) couples various physical fields which is vital to reduce the redundant workload required for SOFC development. Modeling of SOFCs includes the coupling of charge transfer electrochemical reactions fluid flow energy transport and species transport. The Butler‐Volmer equation is frequently used to describe the coupling of electrochemical reactions with current density. The most frequently used is the activation‐ and diffusion‐controlled Butler‐Volmer equation. Three different electrode reaction models are examined in the study which is named case 1 case 2 and case 3 respectively. Case 1 is activation controlled while cases 2 and 3 are diffusion‐controlled which take the concentration of redox species into account. It is shown that case 1 gives the highest reaction rate followed by case 2 and case 3. Case 3 gives the lowest reaction rate and thus has a much lower current density and temperature. The change of activation overpotential does not follow the change of current density and temperature at the interface of the anode and electrolyte and interface of cathode and electrolyte which demonstrates the non‐linearity of the model. This study provides a reference to build electrochemical models of SOFCs and gives a deep understanding of the involved electrochemistry.
Warm Pre-Strain: Strengthening the Metastable 304L Austenitic Stainless Steel without Compromising Its Hydrogen Embrittlement Resistance
Nov 2017
Publication
Plastic pre-strains were applied to the metastable 304L austenitic stainless steel at both room temperature (20 °C) and higher temperatures (i.e. 50 80 and 100 °C) and then the hydrogen embrittlement (HE) susceptibility of the steel was evaluated by cathodically hydrogen-charging and tensile testing. The 20 °C pre-strain greatly strengthened the steel but simultaneously significantly increased the HE susceptibility of the steel since α′ martensite was induced by the pre-strain causing the pre-existence of α′ martensite which provided “highways” for hydrogen to transport deep into the steel during the hydrogen-charging. Although the warm pre-strains did not strengthen the steel as significantly as the 20 °C pre-strain they retained the HE resistance of the steel. This is because the higher temperatures particularly 80 and 100 °C suppressed the α′ martensite transformation during the pre-straining. Pre-strain at a temperature slightly higher than room temperature has a potential to strengthen the metastable 304L austenitic stainless steel without compromising its initial HE resistance.
Recent Progress in the Steam Reforming of Bio-Oil for Hydrogen Production: A Review of Operating Parameters, Catalytic Systems and Technological Innovations
Dec 2021
Publication
The present review focuses on the production of renewable hydrogen through the catalytic steam reforming of bio-oil the liquid product of the fast pyrolysis of biomass. Although in theory the process is capable of producing high yields of hydrogen in practice certain technological issues require radical improvements before its commercialization. Herein we illustrate the fundamental knowledge behind the technology of the steam reforming of bio-oil and critically discuss the major factors influencing the reforming process such as the feedstock composition the reactor design the reaction temperature and pressure the steam to carbon ratio and the hour space velocity. We also emphasize the latest research for the best suited reforming catalysts among the specific groups of noble metal transition metal bimetallic and perovskite type catalysts. The effect of the catalyst preparation method and the technological obstacle of catalytic deactivation due to coke deposition metal sintering metal oxidation and sulfur poisoning are addressed. Finally various novel modified steam reforming techniques which are under development are discussed such as the in-line two-stage pyrolysis and steam reforming the sorption enhanced steam reforming (SESR) and the chemical looping steam reforming (CLSR). Moreover we argue that while the majority of research studies examine hydrogen generation using different model compounds much work must be done to optimally treat the raw or aqueous bio-oil mixtures for efficient practical use. Moreover further research is also required on the reaction mechanisms and kinetics of the process as these have not yet been fully understood.
Digital Navigation of Energy–structure–function Maps for Hydrogen-bonded Porous Molecular Crystals
Feb 2021
Publication
Energy–structure–function (ESF) maps can aid the targeted discovery of porous molecular crystals by predicting the stable crystalline arrangements along with their functions of interest. Here we compute ESF maps for a series of rigid molecules that comprise either a triptycene or a spiro-biphenyl core functionalized with six different hydrogen-bonding moieties. We show that the positioning of the hydrogen-bonding sites as well as their number has a profound influence on the shape of the resulting ESF maps revealing promising structure–function spaces for future experiments. We also demonstrate a simple and general approach to representing and inspecting the high-dimensional data of an ESF map enabling an efficient navigation of the ESF data to identify ‘landmark’ structures that are energetically favourable or functionally interesting. This is a step toward the automated analysis of ESF maps an important goal for closed-loop autonomous searches for molecular crystals with useful functions.
Dynamic Model to Expand Energy Storage in Form of Battery and Hydrogen Production Using Solar Powered Water Electrolysis for Off Grid Communities
Feb 2022
Publication
In this model we used a 50 WP photovoltaic panel to produce electrical energy. This electricity production was used directly and stored in a battery. In this design we coupled batteries and hydrogen as a means of storing energy. In case of overcharging the battery it will be attached with water electrolysis to convert the excess amount of chemical energy of the battery into hydrogen energy storage. Hydrogen will be stored as a compacted gas and in chemical storage. We used PEM (proton exchange membrane) electrolysis technologies to breakdown water molecules into hydrogen and oxygen which were then stored in the designed tanks. Different supply voltages were used in our practical readings with an average gaining of 22.8 mL/min on a voltage supply of 2. While using Ansys simulation software we extrapolated hydrogen production until reaching 300 mL/min on 12 V of supply (which represents 220% higher production). By using the second phase of this model hydrogen energy was converted back into electrical energy with the help of a PEM (proton exchange membrane) fuel cell when needed. This model explores the feasibility of energy storage in the form of hydrogen and chemical energy for off-grid communities and remote areas comprising batteries water electrolysis and fuel cells. The main purpose of hydrogen storage in this system is to store and handle the extra energy of system produced through PV panel and utilize it for any desired requirements.
Effect of Hydrogen-storage Pressure on the Detonation Characteristics of Emulsion Explosives Sensitized by Glass Microballoons
Mar 2021
Publication
In this study hydrogen-storage glass microballoons were introduced into emulsion explosives to improve the detonation performance of the explosives. The effect of hydrogen-storage pressure on the detonation characteristics of emulsion explosives was systematically investigated. Detonation velocity experiments shows that the change of sensitizing gas and the increase of hydrogen pressure have different effects on the detonation velocity. The experimental parameters of underwater explosion increase first and then decreases with the increase of hydrogen pressure. The decrease of these parameters indicates that the strength of glass microballoons is the limiting factor to improve the detonation performance of hydrogen-storage emulsion explosives. Compared with the traditional emulsion explosives the maximum peak pressure of shock wave of hydrogen-storage emulsion explosives increases by 10.6% at 1.0 m and 10.2% at 1.2 m the maximum values of shock impulse increase by 5.7% at 1.0 m and 19.4% at 1.2 m. The stored hydrogen has dual effects of sensitizers and energetic additives which can improve the energy output of emulsion explosives.
Thermodynamic Assessment of a Solar-Driven Integrated Membrane Reactor for Ethanol Steam Reforming
Nov 2020
Publication
To efficiently convert and utilize intermittent solar energy a novel solar-driven ethanol steam reforming (ESR) system integrated with a membrane reactor is proposed. It has the potential to convert low-grade solar thermal energy into high energy level chemical energy. Driven by chemical potential hydrogen permeation membranes (HPM) can separate the generated hydrogen and shift the ESR equilibrium forward to increase conversion and thermodynamic efficiency. The thermodynamic and environmental performances are analyzed via numerical simulation under a reaction temperature range of 100–400 ◦C with permeate pressures of 0.01–0.75 bar. The highest theoretical conversion rate is 98.3% at 100 ◦C and 0.01 bar while the highest first-law efficiency solar-to-fuel efficiency and exergy efficiency are 82.3% 45.3% and 70.4% at 215 ◦C and 0.20 bar. The standard coal saving rate (SCSR) and carbon dioxide reduction rate (CDRR) are maximums of 101 g·m−2 ·h −1 and 247 g·m−2 ·h −1 at 200 ◦C and 0.20 bar with a hydrogen generation rate of 22.4 mol·m−2 ·h −1 . This study illustrates the feasibility of solar-driven ESR integrated with a membrane reactor and distinguishes a novel approach for distributed hydrogen generation and solar energy utilization and upgradation.
Hydrogen Storage Behavior of Mg-based Alloy Catalyzed by Carbon-cobalt Composites
Feb 2021
Publication
The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction. The catalysis of Co@C composites on the hydrogen storage behavior of Mg90Ce5Y5 alloy was investigated in detail by XRD SEM TEM PCI and DSC method. Because of the synergistic catalytic function of C and Co in C@Co nanocomposites the Mg90Ce5Y5 alloy with 10 wt.% C@Co shows the excellent hydrogen absorption and desorption performances. Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300 °C. Meanwhile the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol−1 H2 after the addition of the C@Co composites. This positive effect attributes to the C layer with the high defect density and the Co nanoparticles which reduces the energy barriers for the nucleation of Mg/MgH2 phase and the recombination of hydrogen molecule. Besides the C@Co composites also improve the activation property of the Mg90Ce5Y5 alloy which was fully activated in the first cycle. Moreover the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased. Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy these differences are so small that the improvement on thermodynamics can hardly be seen.
China Progress on Renewable Energy Vehicles: Fuel Cells, Hydrogen and Battery Hybrid Vehicles
Dec 2018
Publication
Clean renewable energy for Chinese cities is a priority in air quality improvement. This paper describes the recent Chinese advances in Polymer Electrolyte Membrane (PEM) hydrogen-fuel-cell-battery vehicles including buses and trucks. Following the 2016 Chinese government plan for new energy vehicles bus production in Foshan has now overtaken that in the EU USA and Japan combined. Hydrogen infrastructure requires much advance to catch up but numbers of filling stations are now increasing rapidly in the large cities. A particular benefit in China is the large number of battery manufacturing companies which fit well into the energy storage plan for hybrid fuel cell buses. The first city to manufacture thousands of PEM-battery hybrid buses is Foshan where the Feichi (Allenbus) company has built a new factory next to a novel fuel cell production line capable of producing 500 MW of fuel cell units per year. Hundreds of these buses are running on local Foshan routes this year while production of city delivery trucks has also been substantial. Results for energy consumption of these vehicles are presented and fitted to the Coulomb theory previously delineated.
Intelligent Natural Gas and Hydrogen Pipeline Dispatching Using the Coupled Thermodynamics-Informed Neural Network and Compressor Boolean Neural Network
Feb 2022
Publication
Natural gas pipelines have attracted increasing attention in the energy industry thanks to the current demand for green energy and the advantages of pipeline transportation. A novel deep learning method is proposed in this paper using a coupled network structure incorporating the thermodynamics-informed neural network and the compressor Boolean neural network to incorporate both functions of pipeline transportation safety check and energy supply predictions. The deep learning model is uniformed for the coupled network structure and the prediction efficiency and accuracy are validated by a number of numerical tests simulating various engineering scenarios including hydrogen gas pipelines. The trained model can provide dispatchers with suggestions about the number of phases existing during the transportation as an index showing safety while the effects of operation temperature pressure and compositional purity are investigated to suggest the optimized productions.
Discussion on the Feasibility of the Integration of Wind Power and Coal Chemical Industries for Hydrogen Production
Oct 2021
Publication
To improve the utilization rate of the energy industry and reduce high energy consumption and pollution caused by coal chemical industries in north western China a planning scheme of a wind‐coal coupling energy system was developed. This scheme involved the analysis method evaluation criteria planning method and optimization operation check for the integration of a comprehensive evaluation framework. A system was established to plan the total cycle revenue to maximize the net present value of the goal programming model and overcome challenges associated with the development of new forms of energy. Subsequently the proposed scheme is demonstrated using a 500‐MW wind farm. The annual capacity of a coal‐to‐methanol system is 50000. Results show that the reliability of the wind farm capacity and the investment subject are the main factors affecting the feasibility of the wind‐coal coupled system. Wind power hydrogen production generates O2 and H2 which are used for methanol preparation and electricity production in coal chemical systems respectively. Considering electricity price constraints and environmental benefits a methanol production plant can construct its own wind farm matching its output to facilitate a more economical wind‐coal coupled system. Owing to the high investment cost of wind power plants an incentive mechanism for saving energy and reducing emissions should be provided for the wind‐ coal coupled system to ensure economic feasibility and promote clean energy transformation.
Research on Multi-Period Hydrogen Refueling Station Location Model in Jiading District
Sep 2021
Publication
The construction of hydrogen refueling stations is an important part of the promotion of fuel cell vehicles. In this paper a multi-period hydrogen refueling station location model is presented that can be applied to the planning and construction of hydrogen infrastructures. Based on the hydrogen demand of fuel cell passenger cars and commercial vehicles the model calculates the hydrogen demand of each zone by a weighting method according to population economic level and education level. Then the hydrogen demand of each period is calculated using the generalized Bass diffusion model. Finally the set covering model is improved to determine the locations of the stations. The new model is applied to the scientific planning of hydrogen refueling stations in Jiading District Shanghai; the construction location and sequence of hydrogen refueling stations in each period are given and the growth trend of hydrogen demand and the promoting effect of hydrogen refueling stations are analyzed. The model adopted in this model is then compared with the other two kinds of node-based hydrogen refueling station location models that have previously been proposed.
Converting Sewage Water into H2 Fuel Gas Using Cu/CuO Nanoporous Photocatalytic Electrodes
Feb 2022
Publication
This work reports on H2 fuel generation from sewage water using Cu/CuO nanoporous (NP) electrodes. This is a novel concept for converting contaminated water into H2 fuel. The preparation of Cu/CuO NP was achieved using a simple thermal combustion process of Cu metallic foil at 550 ◦C for 1 h. The Cu/CuO surface consists of island-like structures with an inter-distance of 100 nm. Each island has a highly porous surface with a pore diameter of about 250 nm. X-ray diffraction (XRD) confirmed the formation of monoclinic Cu/CuO NP material with a crystallite size of 89 nm. The prepared Cu/CuO photoelectrode was applied for H2 generation from sewage water achieving an incident to photon conversion efficiency (IPCE) of 14.6%. Further the effects of light intensity and wavelength on the photoelectrode performance were assessed. The current density (Jph) value increased from 2.17 to 4.7 mA·cm−2 upon raising the light power density from 50 to 100 mW·cm−2 . Moreover the enthalpy (∆H*) and entropy (∆S*) values of Cu/CuO electrode were determined as 9.519 KJ mol−1 and 180.4 JK−1 ·mol−1 respectively. The results obtained in the present study are very promising for solving the problem of energy in far regions by converting sewage water to H2 fuel.
Electrochemical and Stress Corrosion Mechanism of Submarine Pipeline in Simulated Seawater in Presence of Different Alternating Current Densities
Jun 2018
Publication
In this study electrochemical measurements immersion tests and slow strain rate tensile (SSRT) tests were applied to investigate the electrochemical and stress corrosion cracking (SCC) behavior of X70 steel in simulated seawater with the interference of different alternating current (AC) densities. The results indicate that AC significantly strengthens the cathodic reaction especially the oxygen reduction reaction. Simultaneously hydrogen evolution reaction occurs when the limiting diffusion current density of oxygen reaches and thus icorr sharply increases with the increase in AC density. Additionally when AC is imposed the X70 steel exhibits higher SCC susceptibility in the simulated seawater and the susceptibility increases with the increasing AC density. The SCC mechanism is controlled by both anodic dissolution (AD) and hydrogen embrittlement (HE) with the interference of AC.
Optimal Configuration of the Integrated Charging Station for PV and Hydrogen Storage
Oct 2021
Publication
This paper designs the integrated charging station of PV and hydrogen storage based on the charging station. The energy storage system includes hydrogen energy storage for hydrogen production and the charging station can provide services for electric vehicles and hydrogen vehicles at the same time. To improve the independent energy supply capacity of the hybrid charging station and reduce the cost the components are reasonably configured. To minimize the configuration cost of the integrated charging station and the proportion of power purchase to the demand of the charging station the energy flow strategy of the integrated charging station is designed and the optimal configuration model of optical storage capacity is constructed. The NSGA-II algorithm optimizes the non-inferior Pareto solution set and a fuzzy comprehensive evaluation evaluates the optimal configuration.
Improved VSG Control Strategy Based on the Combined Power Generation System with Hydrogen Fuel Cells and Super Capacitors
Oct 2021
Publication
Due to their environmental protection and high power generation efficiency the control technology of hydrogen fuel cells (HFCs) connected to the microgrid has become a research hotspot. However when they encounter peak demand or transient events the lack of power cannot be compensated immediately by HFCs which results in sudden changes of the voltage and frequency. The improved virtual synchronous generator (VSG) control strategy based on HFCs and supercapacitors (SCs) combined power generation system is proposed to overcome this shortcoming in this paper. The small-signal model for designing the combined system parameters is provided which are in accordance with the system loop gain phase angle margin and adjustment time requirements. Besides the voltage and current double closed-loop based on sequence control is introduced in the VSG controller. The second-order generalized integrator (SOGI) is utilized to separate the positive and negative sequence components of the output voltage. At the same time a positive and negative sequence voltage outer loop is designed to suppress the negative sequence voltage under unbalanced conditions thereby reducing the unbalance of the output voltage. Finally simulation results in MATLAB/Simulink environment verify that the proposed method has better dynamic characteristics and higher steady-state accuracy compared with the traditional VSG control
High Performance of Biohydrogen Production in Packed-Filter Bioreactor via Optimizing Packed-Filter Position
Jul 2021
Publication
In this present investigation a packed-filter bioreactor was employed to produce hydrogen utilizing an expired soft drink as a substrate. The effects of feeding substrate concentrations ranging from 19.51 10.19 5.34 3.48 to 2.51 g total sugar/L were examined and the position of the packed filter installed in the bioreactor at dimensionless heights (h/H) of 1/4 2/4 3/4 and 4/4 was studied. The results revealed that with a substrate concentration of 20 g total sugar/L and a hydraulic retention time (HRT) of 1 h a packed filter placed at the half-height position of the bioreactor (h/H 2/4) has the optimal hydrogen production rate hydrogen yield and average biomass concentration in the bioreactor resulting in 55.70 ± 2.42 L/L/d 0.90 ± 0.06 mol H2/mol hexose and 17.86 ± 1.09 g VSS/L. When feeding substrate concentrations varied from 20 10 to 5 g total sugar/L with the packed-filter position at h/H 2/4 Clostridium sp. Clostridium tyrobutyricum and Bifidobacterium crudilactis were the predominant bacteria community. Finally it was discovered that the packed-filter bioreactor can produce stable hydrogen in high-strength organic effluent.
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