China, People’s Republic
Microbial Fuel Cells: Technologically Advanced Devices and Approach for Sustainable/renewable Energy Development
Dec 2021
Publication
There is a huge quantity of energy needs/demands for multiple developmental and domestic activities in the modern era. And in this context consumption of more non-renewable energy is reported and created many problems or issues (availability of fossil fuel stocks in the future period causes a huge quantity of toxic gases or particles or climatic change effects) at the global level. And only sustainable or renewable fuel development can provide alternate fuel and we report from various biological agents processes including microbial biofuel cell applications for future energy needs only. These will not cause any interference in natural resources or services. Microbial biofuel cells utilize the living cell to produce bioelectricity via bioelectrochemical system. It can drive electricity or other energy generation currents via lived cell interaction. Microbial fuel cells (MFCs) and enzymatic biofuel cells with their advancement in design can improve sustainable bio-energy production by proving an efficient conversion system compared to chemical fuels into electric power. Different types of MFCs operation are reported in wastewater treatment with biogas biohydrogen and other biofuel/energy generation. Later biogas can convert into electric power. Hybrid microbial biofuel cell utility with photochemical reaction is found for electricity generation. Recent research and development in microbial biofuel design and its application will emphasize bioenergy for the future.
Efficient Renewable-to-Hydrogen Conversion via Decoupled Electrochemical Water Splitting
Aug 2020
Publication
Water electrolysis powered by renewables provides a green approach to hydrogen production to support the ‘‘hydrogen economy.’’ However the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are tightly coupled in both time and space in traditional water electrolysis which brings inherent operational challenges such as the mixture of H2/O2 and the limited HER rate caused by the sluggish kinetics of OER. Against this background decoupling H2 and O2 production in water electrolysis by using the auxiliary redox mediator was first proposed in 2013 in which O2 and H2 are produced at different times rates and/or locations. The decoupling strategy offers not only a new way to facilitate renewables to H2 but it can also be applied in other chemical or electrochemical processes. This review describes recent efforts to develop high-performance redox mediators optimized strategies in decoupled water electrolysis the design of electrolyzer configuration the challenges faced and the prospective directions.
Wittichenite Semiconductor of Cu3BiS3 Films for Efficient Hydrogen Evolution from Solar Driven Photoelectrochemical Water Splitting
Jun 2021
Publication
A highly efficient low-cost and environmentally friendly photocathode with long-term stability is the goal of practical solar hydrogen evolution applications. Here we found that the Cu3BiS3 film-based photocathode meets the abovementioned requirements. The Cu3BiS3-based photocathode presents a remarkable onset potential over 0.9 VRHE with excellent photoelectrochemical current densities (~7 mA/cm2 under 0 VRHE) and appreciable 10-hour long-term stability in neutral water solutions. This high onset potential of the Cu3BiS3-based photocathode directly results in a good unbiased operating photocurrent of ~1.6 mA/cm2 assisted by the BiVO4 photoanode. A tandem device of Cu3BiS3-BiVO4 with an unbiased solar-to-hydrogen conversion efficiency of 2.04% is presented. This tandem device also presents high stability over 20 hours. Ultimately a 5 × 5 cm2 large Cu3BiS3-BiVO4 tandem device module is fabricated for standalone overall solar water splitting with a long-term stability of 60 hours.
Integral Sliding Mode Control for Maximum Power Point Tracking in DFIG Based Floating Offshore Wind Turbine and Power to Gas
Jun 2021
Publication
This paper proposes a current decoupling controller for a Doubly-fed Induction Generator (DFIG) based on floating offshore wind turbine and power to gas. The proposed controller realizes Maximum Power Point Tracking (MPPT) through integral sliding mode compensation. By using the internal model control strategy an open-loop controller is designed to ensure that the system has good dynamic performance. Furthermore using the integral Sliding Mode Control (SMC) strategy a compensator is designed to eliminate the parameter perturbation and external disturbance of the open-loop control. The parameters of the designed controller are designed through Grey Wolf Optimization (GWO). Simulation results show that the proposed control strategy has better response speed and smaller steady-state error than the traditional control strategy. This research is expected to be applied to the field of hydrogen production by floating offshore wind power.
Comparison Between Hydrogen Production by Alkaline Water Electrolysis and Hydrogen Production by PEM Electrolysis
Sep 2021
Publication
Hydrogen is an ideal clean energy source that can be used as an energy storage medium for renewable energy sources. The water electrolysis hydrogen production technology which is one of the mainstream hydrogen production methods can be used to produce high-purity hydrogen and other energy sources can be converted into hydrogen storage by electrolysis. Hydrogen production by alkaline water electrolysis and hydrogen production by PEM electrolysis are all water electrolysis hydrogen production technologies that have been industrially applied. From the application point of view the paper compares the working principle of the two kinds of electrolyzers the process flow of hydrogen production equipment advantages and disadvantages. This article provides a reference for relevant researchers.
The Effect of Symmetrically Tilt Grain Boundary of Aluminum on Hydrogen Diffusion
Feb 2022
Publication
High-strength aluminum alloys are widely used in industry. Hydrogen embrittlement greatly reduces the performance and service safety of aluminum alloys. The hydrogen traps in aluminum profoundly affect the hydrogen embrittlement of aluminum. Here we took a coincidence-site lattice (CSL) symmetrically tilted grain boundary (STGB) Σ5(120)[001] as an example to carry out molecular dynamics (MD) simulations of hydrogen diffusion in aluminum at different temperatures and to obtain results and rules consistent with the experiment. At 700 K three groups of MD simulations with concentrations of 0.5 2.5 and 5 atomic % hydrogen (at. % H) were carried out for STGB models at different angles. By analyzing the simulation results and the MSD curves of hydrogen atoms we found that in the low hydrogen concentration of STGB models the grain boundaries captured hydrogen atoms and hindered their movement. In high-hydrogen-concentration models the diffusion rate of hydrogen atoms was not affected by the grain boundaries. The analysis of the simulation results showed that the diffusion of hydro-gen atoms at the grain boundary is anisotropic.
Effect of Cementite on the Hydrogen Diffusion/Trap Characteristics of 2.25Cr-1Mo-0.25V Steel with and without Annealing
May 2018
Publication
Hydrogen embrittlement (HE) is a critical issue that affects the reliability of hydrogenation reactors. The hydrogen diffusivity/trap characteristics of 2.25Cr-1Mo-0.25V steel are important parameters mainly used to study the HE mechanism of steel alloys. In this work the hydrogen diffusivity/trap characteristics of heat-treated (annealed) and untreated 2.25Cr-1Mo-0.25V steel were studied using an electrochemical permeation method. The microstructures of both 2.25Cr-1Mo-0.25V steels were investigated by metallurgical microscopy. The effect of cementite on the hydrogen diffusivity/trap mechanisms was studied using thermodynamics-based and Lennard–Jones potential theories. The results revealed that the cementite located at the grain boundaries and at the interfaces of lath ferrite served as a kind of hydrogen trap (i.e. an irreversible hydrogen trap). In addition hydrogen was transported from ferrite to cementite via up-hill diffusion thereby supporting the hypothesis of cementite acting as a hydrogen trap.
Effect of Deformation Microstructures on Hydrogen Embrittlement Sensitivity and Failure Mechanism of 304 Austenitic Stainless Steel: The Significant Role of Rolling Temperature
Feb 2022
Publication
Metastable austenitic stainless steels (ASSs) have excellent ductility but low strength so that their usage as load-bearing components is significantly limited. Rolling is an effective method of increasing strength whereas the effect of rolling temperature on microstructural evolution the hydrogen embrittlement (HE) sensitivity and fracture mechanisms is still unclear. In present study the effect of cold/warm rolling on detailed microstructural characteristics of 304 ASS was quantitatively investigated and the corresponding HE sensitivity was evaluated via slow strain rate test. The results suggest that cold-rolling led to high strength but poor plasticity and deteriorated HE sensitivity while warm-rolled samples provided combination of high strength and ductility and also superior HE resistance. Compared with 18% α′-martensite in cold -rolled steel warm-rolled specimens consisted of complete austenite less twins and lower dislocation density,moreover the favorable {112} ND and {110} ND textures replaced the harmful {001} ND texture. Based on in-situ EBSD observation during SSRT the HE sensitivity was governed by the combined effect of pre-deformation microstructures and the dynamic microstructural evolution. Advanced method of time-of-flight secondary ion mass spectrometry was used to observe the distribution of hydrogen and the hydrogen content of specimens was determined by the gas chromatograph thermal desorption analysis method. An exceedingly small amount of hydrogen entered the warm-rolled samples while a large amount of hydrogen was trapped at grain boundaries of cold-rolled sample leading to complete intergranular fracture. Therefore warm rolling is an effective pathway for obtaining high combination of strength and ductility together with excellent HE sensitivity.
Multi-Criteria Optimization of a Biomass-Based Hydrogen Production System Integrated With Organic Rankine Cycle
Oct 2020
Publication
Biomass-based gasification is an attractive and promising pathway for hydrogen production. In this work a biomass-based hydrogen production system integrated with organic Rankine cycle was designed and investigated to predict the performance of hydrogen production yield and electricity generation under various operating conditions. The modified equilibrium model presented desirable results for the produced syngas compositions compared with the experimental data. Hydrogen yields from four types of biomass (wood chips daily manure sorghum and grapevine pruning wastes) were compared under the same operating condition with wood chips exhibiting the maximum hydrogen yield of 11.59 mol/kg. The effects of gasification temperature equivalence ratio and steam-to-biomass ratio on the hydrogen yield and electricity generation were investigated by using the response surface method. Furthermore the system was optimized using a genetic algorithm based on the response surface model. A preferred optimal solution with a hydrogen yield of 39.31 mol/kg and an output power of 3558.08 kW (0.99 kW h/kg) was selected by the linear programming technique for multidimensional analysis of the preference method.
Study on Flake Formation Behavior and Its Influence Factors in Cr5 Steel
Apr 2018
Publication
A flake is a crack that is induced by trapped hydrogen within steel. To study its formation mechanism previous studies mostly focused on the formation process and magnitude of hydrogen pressure in hydrogen traps such as cavities and cracks. However according to recent studies the hydrogen leads to the decline of the mechanical properties of steel which is known as hydrogen embrittlement is another reason for flake formation. In addition the phenomenon of stress induced hydrogen uphill diffusion should not be neglected. All of the three behaviors are at work simultaneously. In order to further explore the formation mechanism of flakes in steel the process of flake initiation and growth were studied with the following three coupling factors: trap hydrogen pressure hydrogen embrittlement and stress induced hydrogen re-distribution. The analysis model was established using the finite element method and a crack whose radius is 0.5 mm was set in its center. The cohesive method and Bilinear Traction Separate Law (BTSL) were used to address the coupling effect. The results show that trap hydrogen pressure is the main driving force for flake formation. After the high hydrogen pressure was generated around the trap a stress field formed. In addition the trap is the center of stress concentration. Then hydrogen is concentrated in a distribution around this trap and most of the steel mechanical properties are reduced. The trap size is a key factor for defining the critical hydrogen content for flake formation and propagation. However when the trap size exceeds the specified value the critical hydrogen content does not change any more. As for the crack whose radius is 0.5 mm the critical hydrogen content of Cr5VMo steel is 2.2 ppm which is much closer to the maximum safe hydrogen concentration of 2.0 ppm used in China. The work presented in this article increases our understanding of flake formation and propagation mechanisms in steel.
Effect of Hydrogen on Very High Cycle Fatigue Behavior of a Low-strength Cr-Ni-Mo-V Steel Containing Micro-defects
Dec 2017
Publication
The role of hydrogen in fatigue failure of low strength steels is not as well understood as of high strength steels in very high cycle fatigue regime. In this work axially cyclic tests on a low strength Cr-Ni-Mo-V steel with charged hydrogen were carried out up to the very high cycle fatigue regime under ultrasonic frequency to examine the degradation of fatigue strength and associated failure mechanisms. Results show that the S-N curves show a continuously decreasing mode and hydrogen-charged specimens have lower fatigue strength and shorter fatigue lifetime as compared with as-received specimens. It is concluded that the hydrogen trapped by inclusions drives interior micro-defects as dominant crack initiation site and has a clear link to the initiation and early growth of interior fatigue cracks.
Study of the Co-production of Butanol and Hydrogen by Immobilizing Clostridium Acetobutylicum CICC8012
Mar 2019
Publication
Three kinds of carrier materials activated carbon bagasse and brick were used as immobilizing carriers during fermentation by Clostridium acetobutylicum CICC8012. Compared with cell suspended fermentation enhanced fermentation performance was achieved during immobilizing cell fermentation with shorter fermentation time required. During the experiments hydrogen and butanol appear to be competitive events. The best fermentation performance of butanol was obtained in the case of bagasse as immobilizing carrier (5.804g/L of butanol production 0.22g/g of yield and 0.44g/L/h of productivity) while the hydrogen yield was just 1.41 mol/mol. The highest hydrogen productivity (402mL/L/h) and yield (1.808mol/mol glucose) could be obtained in the case of brick as immobilizing carrier while the butanol yield was 0.18 g/g. The highest hydrogen concentration of 66.76 % was obtained in the case of activated carbon as immobilizing carrier.
A Host-guest Approach to Fabricate Metallic Cobalt Nanoparticles Embedded in Silk-derived N-doped Carbon Fibers for Efficient Hydrogen Evolution
Feb 2017
Publication
Hydrogen evolution reaction (HER) plays a key role in generating clean and renewable energy. As the most effective HER electrocatalysts Pt group catalysts suffer from severe problems such as high price and scarcity. It is highly desirable to design and synthesize sustainable HER electrocatalysts to replace the Pt group catalysts. Due to their low cost high abundance and high activities cobalt-incorporated N-doped nanocarbon hybrids are promising candidate electrocatalysts for HER. In this report we demonstrated a robust and eco-friendly host-guest approach to fabricate metallic cobalt nanoparticles embedded in N-doped carbon fibers derived from natural silk fibers. Benefiting from the one-dimensional nanostructure the well-dispersed metallic cobalt nanoparticles and the N-doped thin graphitized carbon layer coating the best Co-based electrocatalyst manifests low overpotential (61 mV@10 mA/cm2) HER activity that is comparable with commercial 20% Pt/C and good stability in acid. Our findings provide a novel and unique route to explore high-performance noble-metal-free HER electrocatalysts.
Acoustic Emission Characteristics of Used 70 MPa Type IV Hydrogen Storage Tanks During Hydrostatic Burst Tests
Sep 2019
Publication
Currently the periodic inspection of composite tanks is typically achieved via hydrostatic test combined with internal and external visual inspections. Acoustic emission (AE) technology demonstrates a promising non destructive testing method for damage mode identification and damage assessment. This study focuses on AE signals characteristics and evolution behaviours for used 70 MPa Type IV hydrogen storage tanks during hydrostatic burst tests. AE-based tensile tests for epoxy resin specimen and carbon fiber tow were implemented to obtain characteristics of matrix cracking and fiber breakage. Then broadband AE sensors were used to capture AE signals during multi-step loading tests and hydrostatic burst tests. K-means ++ algorithm and wavelet packet transform are performed to cluster AE signals and verify the validity. Combining with tensile tests three clusters are manifested via matrix cracking fiber/matrix debonding and fiber breakage according to amplitude duration counts and absolute energy. The number of three clustering signals increases with the increase of pressure showing accumulated and aggravated damage. The sudden appearance of a large number of fiber breakage signals during hydrostatic burst tests suggests that the composite tank structure is becoming mechanically unstable namely the impending burst failure of the tank.
Amorphous Iron-nickel Phosphide Nanocone Arrays as Efficient Bifunctional Electrodes for Overall Water Splitting
May 2020
Publication
The synthesis of low-cost and highly active electrodes for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is very important for water splitting. In this work the novel amorphous iron-nickel phosphide (FeP-Ni) nanocone arrays as efficient bifunctional electrodes for overall water splitting have been in-situ assembled on conductive three-dimensional (3D) Ni foam via a facile and mild liquid deposition process. It is found that the FeP-Ni electrode demonstrates highly efficient electrocatalytic performance toward overall water splitting. In 1 M KOH electrolyte the optimal FeP-Ni electrode drives a current density of 10 mA/cm2 at an overpotential of 218 mV for the OER and 120 mV for the HER and can attain such current density for 25 h without performance regression. Moreover a two-electrode electrolyzer comprising the FeP-Ni electrodes can afford 10 mA/cm2 electrolysis current at a low cell voltage of 1.62 V and maintain long-term stability as well as superior to that of the coupled RuO2/NF‖Pt/C/NF cell. Detailed characterizations confirm that the excellent electrocatalytic performances for water splitting are attributed to the unique 3D morphology of nanocone arrays which could expose more surface active sites facilitate electrolyte diffusion benefit charge transfer and also favourable bubble detachment behaviour. Our work presents a facile and cost-effective pathway to design and develop active self-supported electrodes with novel 3D morphology for water electrolysis.
Spin Pinning Effect to Reconstructed Oxyhydroxide Layer on Ferromagnetic Oxides for Enhanced Water Oxidation
Jun 2021
Publication
Producing hydrogen by water electrolysis suffers from the kinetic barriers in the oxygen evolution reaction (OER) that limits the overall efficiency. With spin-dependent kinetics in OER to manipulate the spin ordering of ferromagnetic OER catalysts (e.g. by magnetization) can reduce the kinetic barrier. However most active OER catalysts are not ferromagnetic which makes the spin manipulation challenging. In this work we report a strategy with spin pinning effect to make the spins in paramagnetic oxyhydroxides more aligned for higher intrinsic OER activity. The spin pinning effect is established in oxideFM/oxyhydroxide interface which is realized by a controlled surface reconstruction of ferromagnetic oxides. Under spin pinning simple magnetization further increases the spin alignment and thus the OER activity which validates the spin effect in rate-limiting OER step. The spin polarization in OER highly relies on oxyl radicals (O∙) created by 1st dehydrogenation to reduce the barrier for subsequent O-O coupling.
Design and Performance of a Compact Air-Breathing Jet Hybrid-Electric Engine Coupled With Solid Oxide Fuel Cells
Feb 2021
Publication
A compact air-breathing jet hybrid-electric engine coupled with solid oxide fuel cells (SOFC) is proposed to develop the propulsion system with high power-weight ratios and specific thrust. The heat exchanger for preheating air is integrated with nozzles. Therefore the exhaust in the nozzle expands during the heat exchange with compressed air. The nozzle inlet temperature is obviously improved. SOFCs can directly utilize the fuel of liquid natural gas after being heated. The performance parameters of the engine are acquired according to the built thermodynamic and mass models. The main conclusions are as follows. 1) The specific thrust of the engine is improved by 20.25% compared with that of the traditional jet engine. As pressure ratios rise the specific thrust increases up to 1.7 kN/(kg·s−1). Meanwhile the nozzle inlet temperature decreases. However the temperature increases for the traditional combustion engine. 2) The power-weight ratio of the engine is superior to that of internal combustion engines and inferior to that of turbine engines when the power density of SOFC would be assumed to be that predicted for 2030. 3) The total pressure recovery coefficients of SOFCs combustors and preheaters have an obvious influence on the specific thrust of the engine and the power-weight ratio of the engine is strongly affected by the power density of SOFCs.
Catalyst Engineering for Electrochemical Energy Conversion from Water to Water: Water Electrolysis and the Hydrogen Fuel Cell
May 2020
Publication
In the context of the current serious problems related to energy demand and climate change substantial progress has been made in developing a sustainable energy system. Electrochemical hydrogen–water conversion is an ideal energy system that can produce fuels via sustainable fossil-free pathways. However the energy conversion efficiency of two functioning technologies in this energy system—namely water electrolysis and the fuel cell—still has great scope for improvement. This review analyzes the energy dissipation of water electrolysis and the fuel cell in the hydrogen–water energy system and discusses the key barriers in the hydrogen- and oxygen-involving reactions that occur on the catalyst surface. By means of the scaling relations between reactive intermediates and their apparent catalytic performance this article summarizes the frameworks of the catalytic activity trends providing insights into the design of highly active electrocatalysts for the involved reactions. A series of structural engineering methodologies (including nanoarchitecture facet engineering polymorph engineering amorphization defect engineering element doping interface engineering and alloying) and their applications based on catalytic performance are then introduced with an emphasis on the rational guidance from previous theoretical and experimental studies. The key scientific problems in the electrochemical hydrogen–water conversion system are outlined and future directions are proposed for developing advanced catalysts for technologies with high energy-conversion efficiency.
An Investigation of Gaseous Hydrogen Storage Characterizations of Mg–Y–Ni–Cu Alloys Synthesized by Melt Spinning
Aug 2018
Publication
Melt spinning was successfully utilized to prepare Mg25−xYxNi9Cu (x = 0 1 3 5 7) alloys producing nanocrystalline and amorphous structures with improved hydrogenation and dehydrogenation performances. The influence of spinning rate on hydrogenation and dehydrogenation thermodynamics and kinetics was studied in detail. XRD and TEM were utilized to characterize the alloy structures. Hydrogenation and dehydrogenation performances were investigated by Sievert apparatus DSC and TGA connected to a H2 detector. Dehydrogenation activation energies were estimated using both Arrhenius and Kissinger methods. Results show that melt spinning significantly decreases thermodynamic parameters (ΔH and ΔS) and ameliorates desorption kinetics. Dehydrogenation activation energy markedly lowers with increase in spinning rate and is the real driver of amelioration of dehydrogenation kinetics caused by increasing Y content.
Comprehensive Performance Evaluation of Densified Liquid Hydrogen/Liquid Oxygen as Propulsion Fuel
Jan 2022
Publication
Densified liquid hydrogen/liquid oxygen is a promising propulsion fuel in the future. In order to systematically demonstrate the benefits and challenges of densified liquid hydrogen/liquid oxygen a transient thermodynamical model considering the heat leakage temperature rise engine thrust pressurization pressure of the tank and wall thickness of tank is developed in the present paper and the performance of densified liquid hydrogen/liquid oxygen as propulsion fuel is further evaluated in actual application. For liquid hydrogen/liquid oxygen tanks at different structural dimensions the effects of many factors such as temperature rise during propellant ground parking lift of engine thrust mass reduction of the tank structure and extension of spacecraft in‐orbit time are analyzed to demonstrate the comprehensive performance of liquid hydrogen/liquid oxygen after densification. Meanwhile the problem of subcooling combination matching of liquid hydro‐ gen/liquid oxygen is proposed for the first time. Combining the fuel consumption and engine thrust lifting the subcooling combination matching of liquid hydrogen/liquid oxygen at different mixing ratios and constant mixing ratios are discussed respectively. The results show that the relative engine thrust enhances by 6.96% compared with the normal boiling point state in the condition of slush hydrogen with 50% solid content and enough liquid oxygen. The in‐orbit time of spacecraft can extend about 2–6.5 days and 24–95 days for slush hydrogen with 50% solid content and liquid oxygen in the triple point state in different cryogenic tanks respectively. Due to temperature rise during parking the existing adiabatic storage scheme and filling scheme for densification LH2 need to be redesigned and for densification LO2 are suitable. It is found that there is an optimal subcooling matching relation after densification of liquid hydrogen/liquid oxygen as propulsion fuel. In other words the subcooling temperature of liquid hydrogen/liquid oxygen is not the lower the bet‐ ter but the matching relationship between LH2 subcooling degree and LO2 subcooling degree needs to be considered at the same time. It is necessary that the LO2 was cooled to 69.2 K and 54.5 K when the LH2 of 13.9 K and SH2 with 45% was adopted respectively. This research provides theoretical support for the promotion and application of densification cryogenic propellants.
No more items...