China, People’s Republic

Many countries including China have implemented supporting policies to promote the commercialized application of green hydrogen and hydrogen fuel cells. In this study a system dynamics (SD) model is proposed to study the evolution of hydrogen demand in China from the petroleum refining industry the synthetic ammonia industry and the vehicle market. In the model the impact from the macro-environment hydrogen fuel supply and construction of hydrogen facilities is considered to combine in incentives for supporting policies. To further formulate the competitive relationship in the vehicle market the Lotka–Volterra (LV) approach is adopted. The model is verified using published data from 2003 to 2017. The model is also used to forecast China’s hydrogen demand up to the year of 2030 under three different scenarios. Finally some forward-looking guidance is provided to policy makers according to the forecasting results.

The influence of plastic deformation on hydrogen diffusion is of critical significance for hydrogen embrittlement (HE) studies. In this work thermal desorption spectroscope (TDS) slow strain rate test (SSRT) feritscope transmission electron microscope (TEM) and TDS model are used to establish the relationship between plastic deformation and hydrogen diffusion aiming at unambiguously elucidating the effect of pre-existing traps on hydrogen diffusion of hot-rolled S30408. An effective way is developed to deduce hydrogen apparent diffusivity in this paper. Results indicate apparent diffusivities decrease firstly and then increase with increasing plastic strain at room temperature. Hydrogen diffusion changing with plastic deformation is a complicated process involving multiple factors. It is suggested to be divided into two processes controlled by dislocations and strain-induced martensite respectively and the transformation strain is about 20% demonstrated by experiments.

Hydrogen embrittlement (HE) together with the hydrogen transport behaviour in hydrogen-charged type 304 stainless steel was investigated by combined tension and outgassing experiments. The hydrogen release rate and HE of hydrogen-charged 304 specimens increase with the hydrogen pressure for hydrogen-charging (or hydrogen content) and almost no HE is observed below the hydrogen content of 8.5 mass ppm. Baking at 433 K for 48 h can eliminate HE of the hydrogen-charged 304 specimen while removing the surface layer will restore HE which indicates that hydrogen in the surface layer plays the primary role in HE. Scanning electron microscopy (SEM) and scanning tunnel microscopy (STM) observations show that particles attributed to the strain-induced α′ martensite formation break away from the matrix and the small holes form during deformation on the specimen surface. With increasing strain the connection among small holes along {111} slip planes of austenite will cause crack initiation on the surface and then the hydrogen induced crack propagates from the surface to interior.

This manuscript presents the results of a multi-lateral international activity intended to understand how to execute a cycle stress test as specified in a chosen standard (GTR SAE ISO EIHP …). The purpose of this work was to establish a harmonized test method protocol to ensure that the same results would be achieved regardless of the testing facility. It was found that accurate temperature measurement of the working fluid is necessary to ensure the test conditions remain within the tolerances specified. Continuous operation is possible with adequate cooling of the working fluid but this becomes more demanding if the cycle frequency increases. Recommendations for future test system design and operation are presented.

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.

Diffusion coefficient is in significant dependence on vacancy concentration due to that migration of vacancy is the dominant mechanism of atom transport or diffusion in processes such as void formation dislocation movement and solid phase transformation. This study aims to investigate the effect of vacancy concentration on hydrogen diffusion in alpha-Fe by molecular dynamics simulations especially at low temperatures and with loading. Comparisons of the diffusion coefficients between alpha-Fe with a perfect structure and different-concentration vacancies as well as comparisons between experimental and theoretical results had been made to characterize and summarize the effect of vacancy on hydrogen diffusion coefficient.

The effects of sponge blockage ratio on flame structure evolution and flame acceleration were experimentally investigated in an obstructed cross-section tube filled with stoichiometric hydrogen-air mixture. Experimental results show that the mechanisms responsible for flame acceleration can be in terms of the positive feedback of the unburned gas field generated ahead of the flame the area change of the gap between the sponge and the tube and the interaction between the flame and the shear layer appearing at the sponge left top corner. Especially the last one dominates the flame acceleration and causes its speed to be sonic. Then both the second and third contribute to the violent flame acceleration. In addition the unburned gas pockets can be found in both upstream and downstream regions of the sponge. With increasing blockage ratio the unburned gas pockets disappear easier and the flame acceleration is more pronounced. Moreover the sponge tilts more evidently and resultantly the maximum tilt angle increases.

Hydrogen is considered to be a very promising potential energy carrier due to its excellent characteristics such as abundant resources high fuel value clean and renewable. Its safety features greatly influence the potential use. Several safety problems need to be analyzed before using in transportation industry. With the development of the tunnel transportation technology the safe use of hydrogen in tunnels will receive a lot of research attentions. In this article the risk associated with hydrogen release from onboard high-pressure vessels and the induced combustion in tunnels was analyzed using the Partially Averaged Navier–Stokes (PANS) turbulence model. The influences of the tunnel ventilation facilities on the hydrogen flow characteristics and the flammable hydrogen cloud sizes were studied. The tunnel layouts were designed according to the subsea tunnel. And a range of longitudinal ventilation conditions had been considered to investigate the hydrogen releases and the sizes of the flammable hydrogen cloud. Then the hydrogen combustion simulation was carried out after the fixed leaking time. The overpressures induced after the ignition of leaking hydrogen were studied. The influences of ventilation and ignition delay time on the overpressure were also investigated. The main aim was to research the phenomena of hydrogen releases and combustion risk inside subsea tunnels and to lay the foundation of risk assessment methodology developed for hydrogen energy applications on transportation.

The use of so-called “green” hydrogen for decarbonisation of the energy and propulsion sectors has attracted considerable attention over the last couple of decades. Although advancements are achieved hydrogen still presents some constraints when used directly in power systems such as gas turbines. Therefore another vector such as ammonia can serve as a chemical to transport and distribute green hydrogen whilst its use in gas turbines can limit combustion reactivity compared to hydrogen for better operability. However pure ammonia on its own shows slow complex reaction kinetics which requires its doping by more reactive molecules thus ensuring greater flame stability. It is expected that in forthcoming years ammonia will replace natural gas (with ~ 90% methane in volume) in power and heat production units thus making the co-firing of ammonia/methane a clear path towards replacement of CH4 as fossil fuel. Hydrogen can be obtained from the precracking of ammonia thus denoting a clear path towards decarbonisation by the use of ammonia/hydrogen blends. Therefore ammonia/methane/hydrogen might be co-fired at some stage in current combustion units hence requiring a more intrinsic analysis of the stability emissions and flame features that these ternary blends produce. In return this will ensure that transition from natural gas to renewable energy generated e-fuels such as so-called “green” hydrogen and ammonia is accomplished with minor detrimentals towards equipment and processes. For this reason this work presents the analysis of combustion properties of ammonia/methane/hydrogen blends at different concentrations. A generic tangential swirl burner was employed at constant power and various equivalence ratios. Emissions OH*/NH*/NH2*/CH* chemiluminescence operability maps and spectral signatures were obtained and are discussed. The extinction behaviour has also been investigated for strained laminar premixed flames. Overall the change from fossils to e-fuels is led by the shift in reactivity of radicals such as OH CH CN and NH2 with an increase of emissions under low and high ammonia content. Simultaneously hydrogen addition improves operability when injected up to 30% (vol) an amount at which the hydrogen starts governing the reactivity of the blends. Extinction strain rates confirm phenomena found in the experiments with high ammonia blends showing large discrepancies between values at different hydrogen contents. Finally a 20/55/25% (vol) methane/ammonia/hydrogen blend seems to be the most promising at high equivalence ratios (1.2) with no apparent flashback low emissions and moderate formation of NH2/OH radicals for good operability.

Faced with key obstacles such as the short driving range long charging time and limited volume allowance of battery−−powered electric light scooters in Asian cities the aim of this study is to present a passive fuel cell/battery hybrid system without DC−−DC to ensure a compact volume and low cost. A novel topology structure of the passive fuel cell/battery power system for the electric light scooter is proposed and the passive power system runs only on hydrogen. The power performance and efficiency of the passive power system are evaluated by a self−developed test bench before installation into the scooters. The results of this study reveal that the characteristics of stable power output quick response and the average efficiency are as high as 88% during the Shanghainese urban driving cycle and 89.5% during the Chinese standard driving cycle. The results pre‐ sent the possibility that this passive fuel cell/battery hybrid powertrain system without DC−DC is practical for commercial scooters.

In this paper the accidental release of hydrogen from cryogenic liquid storage tank and the subsequent consequences are studied including hydrogen cold cloud fire ball jet fire flash fire and vapor cloud explosion. The cold effect thermal effects and explosion overpressures from the above consequences are evaluated using IGC and TNO harm criteria. Results show that for instantaneous releases of liquid hydrogen the sequence of harm effect distances is that vapor cloud explosion>flash fire>cold cloud> fireball. For continuous releases of liquid hydrogen the sequence of harm effect distances is that vapor cloud explosion>jet fire>flash fire>cold cloud. The vapor cloud explosion is the leading consequence of both instantaneous and continuous releases and may be used for the determination of safety distances of a liquid hydrogen tank. Besides the harm effect distances of liquid hydrogen tank are compared with those of compressed hydrogen storages with equivalent mass. Results show that the liquid hydrogen storage may be safer than 70MPa gaseous storage in case of leak scenario but may be more dangerous than 70MPa storage in case of catastrophic rupture. It is difficult to tell which storage is safer from a consequence perspective. Further investigation need to be made from a standpoint of risk which combined both consequences and the likelihood of scenarios.

Activated carbons with different surface chemistry and porous textures were used to study the mechanism of electrochemical hydrogen and oxygen evolution in supercapacitor devices. Cellulose precursor materials were activated with different potassium hydroxide (KOH) ratios and the electrochemical behaviour was studied in 6 M KOH electrolyte. In situ Raman spectra were collected to obtain the structural changes of the activated carbons under severe electrochemical oxidation and reduction conditions and the obtained data were correlated to the cyclic voltammograms obtained at high anodic and cathodic potentials. Carbon-hydrogen bonds were detected for the materials activated at high KOH ratios which form reversibly under cathodic conditions. The influence of the specific surface area narrow microporosity and functional groups in the carbon electrodes on their chemical stability and hydrogen capture mechanism in supercapacitor applications has been revealed.

Developing low-cost high-performance catalysts is of fundamental significance for electrochemical energy conversion and storage. In recent years metal@carbon core@shell nanocomposites have emerged as a unique class of functional nanomaterials that show apparent electrocatalytic activity towards a range of reactions such as hydrogen evolution reaction oxygen evolution reaction oxygen reduction reaction and CO2 reduction reaction that are important in water splitting fuel cells and metal-air batteries. The activity is primarily attributed to interfacial charge transfer from the metal core to the carbon shell that manipulate the electronic interactions between the catalyst surface and reaction intermediates and varies with the structures and morphologies of the metal core (elemental composition core size etc.) and carbon shell (doping layer thickness etc.). Further manipulation can be achieved by the incorporation of a third structural component. A perspective is also included highlighting the current gap between theoretical modeling and experimental results and technical challenges for future research.

With the simple structure and quick refuelling process the compressed hydrogen storage system is currently widely used. However thermal effects during charging-discharging cycle may induce temperature change in storage tank which has significant impact on the performance of hydrogen storage and the safety of hydrogen storage tank. To address this issue we once propose a single zone lumped parameter model to obtain the analytical solution of hydrogen temperature and use the analytical solution to estimate the hydrogen temperature but the effect of the tank wall is ignored. For better description of the heat transfer characteristics of the tank wall a dual zone (hydrogen gas and tank wall) lumped parameter model will be considered for widely representation of the reference (experimental or simulated) data. Now we extend the single zone model to the dual zone model which uses two different temperatures for gas zone and wall zone. The dual zone model contains two coupled differential equations. To solve them and obtain the solution we use the method of decoupling the coupled differential equations and coupling the solutions of the decoupled differential equations. The steps of the method include: (1) Decoupling of coupled differential equations; (2) Solving decoupled differential equations; (3) Coupling of solutions of differential equations; (4) Solving coupled algebraic equations. Herein three cases are taken into consideration: constant inflow/outflow temperature variable inflow/outflow temperature and constant inflow temperature and variable outflow temperature. The corresponding approximate analytical solutions of hydrogen temperature and wall temperature can be obtained. The hydrogen pressure can be calculated from the hydrogen temperature and the hydrogen mass using the equation of state for ideal gas. Besides the two coupled differential equations can also be solved numerically and the simulated solution can also be obtained. This study will help to set up a formula based approach of refuelling protocol for gaseous hydrogen vehicles.

Hydrogen mixed natural gas for combustion can improve combustion characteristics and reduce carbon emission which has important engineering application value. A casing swirl burner model is adopted to numerically simulate and research the natural gas hydrogen mixing technology for combustion in gas boilers in this paper. Under the condition of conventional air atmosphere and constant air excess coefficient the six working conditions for hydrogen mixing proportion into natural gas are designed to explore the combustion characteristics and the laws of pollution emissions. The temperature distributions composition and emission of combustion flue gas under various working conditions are analyzed and compared. Further investigation is also conducted for the variation laws of NOx and soot generation. The results show that when the boiler heating power is constant hydrogen mixing will increase the combustion temperature accelerate the combustion rate reduce flue gas and CO2 emission increase the generation of water vapor and inhibit the generation of NOx and soot. Under the premise of meeting the fuel interchangeability it is concluded that the optimal hydrogen mixing volume fraction of gas boilers is 24.7%.

Hydrogen production by steam reforming of ethylene glycol (EG) at 300 °C was investigated over SiO2 and CeO2 supported Pt–Ni bimetallic catalysts prepared by incipient wetness impregnation methods. It was observed that impregnation sequence of Pt and Ni can affect the performance of catalysts apparently. Catalyst with Pt first and then Ni addition showed higher EG conversion and H2 yield owing to the Ni enrichment on the surface and the proper interaction between Pt and Ni. It was observed that although SiO2 supported catalysts exhibited better activity and H2 selectivity CeO2 supported ones had better stability. This is attributed to the less coke formation on CeO2. Increasing Pt/Ni ratio enhanced the reaction activity and Pt3–Ni7 catalysts with 3 wt% Pt and 7 wt% Ni showed the highest activity and stability. Ni surficial enrichment facilitated the C—C bond rupture and water gas shift reactions; and Pt addition inhibited methanation reaction. Electron transfer and hydrogen spillover from Pt to Ni suppressed carbon deposition. These combined effects lead to the excellent performance of Pt3–Ni7 supported catalysts.

Experimental research on performance and emissions of engine fuelled with low calorific value gas blended with hydrogen was carried out and indicated thermal efficiency engine torque indicator diagram pressure rise rate and emissions with different hydrogen ratios were also analyzed. Experimental results show that with the increase of hydrogen fraction and CNG fraction in mixtures the indicated thermal efficiency increased. The engine power output is influenced by both low calorific value and hydrogen fractions. With the increase of hydrogen fraction in mixtures HC emissions decrease CO and NOx emissions increase. An engine operating on lean-burn low calorific value gas blended with hydrogen is favourable for getting lower emissions.

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.

In this work first-principles methods were performed to simulate interactions between hydrogen and common alloying elements of high strength low alloy (HSLA) steel. The world has been convinced that hydrogen could be one of the future clean energy sources. HSLA steel with a balance of strength toughness and hydrogen embrittlement susceptibility is expected for application in large-scale hydrogen storage and transportation. To evaluate the property deterioration under a hydrogen atmosphere hydrogen embrittlement (HE) of HSLA steel attracts attention. However due to the small size of hydrogen atoms the mechanism of HE is challenging to observe directly by current experimental methods. To understand the HE mechanism at an atomic level DFT methods were applied to simulate the effects of alloying elements doping in bcc-Fe bulk structure and grain boundary structure. Furthermore the potential application of DFT to provide theoretical advice for HSLA steel design is discussed.

The Pr and Sm co-doped ceria (with up to 20 mol.% of dopants) compounds were examined as catalytic layers on the surface of SOFC anode directly fed by biogas to increase a lifetime and the efficiency of commercially available DIR-SOFC without the usage of an external reformer.

The XRD SEM and EDX methods were used to investigate the structural properties and the composition of fabricated materials. Furthermore the electrical properties of SOFCs with catalytic layers deposited on the Ni-YSZ anode were examined by a current density-time and current density-voltage dependence measurements in hydrogen (24 h) and biogas (90 h). Composition of the outlet gasses was in situ analysed by the FTIR-based unit.

It has been found out that Ce_0.9Sm_0.1O_2-δ and Ce_0.8Pr_0.05Sm_0.15O_2-δ catalytic layers show the highest stability over time and thus are the most attractive candidates as catalytic materials in comparison with other investigated lanthanide-doped ceria enhancing direct internal reforming of biogas in SOFCs.

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 favorable bubble detachment behavior. Our work presents a facile and cost-effective pathway to design and develop active self-supported electrodes with novel 3D morphology for water electrolysis.

Spontaneous ignition of compressed hydrogen release through a length of tube with different internal geometries is numerically investigated using our previously developed model. Four types of internal geometries are considered: local contraction local enlargement abrupt contraction and abrupt enlargement. The presence of internal geometries was found to significantly increase the propensity to spontaneous ignition. Shock reflections from the surfaces of the internal geometries and the subsequent shock interactions further increase the temperature of the combustible mixture at the contact region. The presence of the internal geometry stimulates turbulence enhanced mixing between the shock-heated air and the escaping hydrogen resulting in the formation of more flammable mixture. It was also found that forward-facing vertical planes are more likely to cause spontaneous ignition by producing the highest heating to the flammable mixture than backward-facing vertical planes.

Hydrogen energy is a clean zero-carbon long-term storage flexible and efficient secondary energy. Accelerating the development of the hydrogen energy industry is a strategic choice to cope with global climate change achieve the goal of carbon neutrality and realize high-quality economic and social development. This study aimed to analyze the economic impact of introducing valueadded services to the hydrogen energy market on hydrogen energy suppliers. Considering the network effect of value-added services this study used a two-stage game model to quantitatively analyze the revenue of hydrogen energy suppliers under different scenarios and provided the optimal decision. The results revealed that (1) the revenue of a hydrogen energy supplier increases only if the intrinsic value of value-added services exceeds a certain threshold; (2) the revenue of hydrogen energy suppliers is influenced by a combination of four key factors: the intrinsic value of value-added services network effects user scale and the sales strategies of rivals; (3) the model developed in this paper can provide optimal decisions for hydrogen energy suppliers to improve their economic efficiency and bring more economic investment to hydrogen energy market in the future.

For the emerging hydrogen-powered vehicles the safety concern is one of the most important barriers for their further development and commercialization. The safety of commercial natural gas vehicles has been well accepted and the total number of natural gas vehicles operating worldwide was approximately 23 million by November 2016. Hydrogen vehicles would be more acceptable for the general public if their safety is comparable to that of commercialized CNG vehicles. A comparison study is conducted to reveal the differences of hazard distances and accident durations between hydrogen vehicles and CNG vehicles during a representative accident in an open environment. The tank blowdown time for hydrogen and CNG are calculated separately to compare the accident durations. CFD simulations for real world situations are performed to study the hazard distances from impinging jet fires under vehicle. Results show that the release duration for CNG vehicle is over two times longer than that for hydrogen vehicle indicating that CNG vehicle jet fire accident is more timeconsuming and firefighters have to wait a longer time before they can safely approach the vehicle. For both hydrogen vehicle and CNG vehicle the longest hazard distance near the ground occur about 1 to 4 seconds after the initiation of the thermally-activated pressure relief devices. Afterwards the flames will shrink and the hazard distances will decrease. For firefighters with bunker gear they must stand 6 m and 14 m away from the hydrogen vehicle and CNG vehicle respectively. For general public a perimeter of 12 m and 29 m should be set around the accident scene for hydrogen vehicle and CNG vehicle respectively.

Previous studies have shown that the two-layer model more accurately predicts hydrogen dispersion than the conventional notional nozzle models without significantly increasing the computational expense. However the model was only validated for predicting the concentration distribution and has not been adequately validated for predicting the velocity distributions. In the present study particle imaging velocimetry (PIV) was used to measure the velocity field of an underexpanded hydrogen jet released at 10 bar from a 1.5 mm diameter orifice. The two-layer model was the used to calculate the inlet conditions for a two-dimensional axisymmetric CFD model to simulate the hydrogen jet downstream of the Mach disk. The predicted velocity spreading and centerline decay rates agreed well with the PIV measurements. The predicted concentration distribution was consistent with data from previous planar Rayleigh scattering measurements used to verify the concentration distribution predictions in an earlier study. The jet spreading was also simulated using several widely used notional nozzle models combined with the integral plume model for comparison. These results show that the velocity and concentration distributions are both better predicted by the two-layer model than the notional nozzle models to complement previous studies verifying only the predicted concentration profiles. Thus this study shows that the two-layer model can accurately predict the jet velocity distributions as well as the concentration distributions as verified earlier. Though more validation studies are needed to improve confidence in the model and increase the range of validity the present work indicates that the two-layer model is a promising tool for fast accurate predictions of the flow fields of underexpanded hydrogen jets.