China, People’s Republic

As the energy crisis and environment pollution growing severely the hydrogen fuel motor vehicle has got more and more attention many automobile companies and research institutions invest significant R&D resources to research and develop the hydrogen fuel vehicles. With the development of the hydrogen fuel cell vehicles and hydrogen fuel motor vehicles the hydrogen had more to more extensive application. According to the categories of the hydrogen fuel vehicles the characteristics of hydrogen fuel vehicle fire risk and accidents are analyzed in this paper. As for hydrogen fuel cell vehicles the function of its key components such as the fuel cell the high-pressure storage tank is presented firstly. Then based on the low density fast diffusion and flammable of hydrogen the probable scenarios of accident such as fuel leak jet flame are analyzed and the fire risk of the key components and the whole vehicle is evaluated. Finally the development trend of the emergency warning system of hydrogen fuel cell vehicles is analyzed and some recommendations are proposed referring to the detection pre-warning and control technologies used in the industrial sites. Aiming at the hydrogen car structure characteristics and the fire accident modes and accidents evolution rules the emergency disposal technology system for hydrogen fuel motor vehicles is put forward.

Melt spinning was successfully utilized to prepare Mg₂₅−_xY_xNi₉Cu (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.

China has plenty of renewable energy like wind power and solar energy especially in the northwest part of the country. Due to the volatile and intermittent characters of the green powers high penetration level of renewable resources could arise grid stabilization problem. Therefore electricity storage is considered as a solution and hydrogen energy storage is proposed. Instead of storing the electricity directly it converts electricity into hydrogen and the energy in hydrogen will be released as needed from gas to electricity and heat. The transformed green power can be fed to the power grid and heat supply network. State Grid Corporation of China carried out its first hydrogen demonstration project. In the demonstration project an alkaline electrolyzer and a PEM hydrogen fuel cell stack are decided as the hydrogen producer and consumer respectively. Hydrogen safety issue is always of significant importance to secure the property. In order to develop a dedicated safety analysis method for hydrogen energy storage system in power industry the risk analysis for the power-to-gas-topower&heat facility was made. The hazard and operability (HAZOP) study and the failure mode and effects analysis (FMEA) are performed sequentially to the installation to identify the most problematic parts of the system in view of hydrogen safety and possible failure modes and consequences. At the third step the typical hydrogen leak accident scenarios are simulated by using computational fluid dynamics (CFD) computer code. The resulted pressure loads of the possibly ignited hydrogen-air mixture in the facility container are estimated conservatively. Important safeguards and mitigation measures are proposed based on the three-stage risk and safety studies.

In this review we primarily analyze the hydrogen production technologies based on water and biomass including the economic technological and environmental impacts of different types of hydrogen production technologies based on these materials and comprehensively compare them. Our analyses indicate that all renewable energy-based approaches for hydrogen production are more environmentally friendly than fossil-based hydrogen generation approaches. However the technical ease and economic efficiency of hydrogen production from renewable sources of energy needs to be further improved in order to be applied on a large scale. Compared with other renewable energy-based methods hydrogen production via biomass electrolysis has several advantages including the ease of directly using raw biomass. Furthermore its environmental impact is smaller than other approaches. Moreover using a noble metal catalyst-free anode for this approach can ensure a considerably low power consumption which makes it a promising candidate for clean and efficient hydrogen production in the future.

Operating chemical looping process at mid-temperatures (550-750 oC) presents exciting potential for the stable production of hydrogen. However the reactivity of oxygen carriers is compromised by the detrimental effect of the relatively low temperatures on the redox kinetics. Although the reactivity at mid-temperature can be improved by the addition of noble metals the high cost of these noble metal containing materials significantly hindered their scalable application. In the current work we propose to incorporate earth-abundant metals into the iron-based spinel for hydrogen production in a chemical looping scheme at mid-temperatures. Mn0.2Co0.4Fe2.4O4 shows a high hydrogen production rate at the average rate of ∼0.62 mmol.g-1.min-1 and a hydrogen yield of ∼9.29 mmol.g-1 with satisfactory stability over 20 cycles at 550 oC. The mechanism studies manifest that the enhanced hydrogen production performance is a result of the improved oxygen-ion conductivity to enhance reduction reaction and high reactivity of reduced samples with steam. The performance of the oxygen carriers in this work is comparable to those noble-metal containing materials enabling their potential for industrial applications.

CO₂ capture utilization and storage (CCUS) is recognized as a uniquely important option in global efforts to control anthropogenic greenhouse-gas (GHG) emissions. Despite significant progress globally in advancing the maturity of the various component technologies and their assembly into full-chain demonstrations a gap remains on the path to widespread deployment in many countries. In this paper we focus on the importance of business models adapted to the unique technical features and sociopolitical drivers in different regions as a necessary component of commercial scale-up and how lessons might be shared across borders. We identify three archetypes for CCUS development—resource recovery green growth and low-carbon grids—each with different near-term issues that if addressed will enhance the prospect of successful commercial deployment. These archetypes provide a framing mechanism that can help to translate experience in one region or context to other locations by clarifying the most important technical issues and policy requirements. Going forward the archetype framework also provides guidance on how different regions can converge on the most effective use of CCUS as part of global deep-decarbonization efforts over the long term.

As one of the most promising alternative fuels hydrogen is expected with high hopes. The electrolysis of water is regarded as the cleanest and most efficient method of hydrogen production. Molybdenum disulfide (MoS2) is deemed as one of the most promising alternatives HER catalysts owing to its high catalytic activity and low cost. Its continuous production and efficient preparation become the key problems in future industrial production. In this work we first developed a continuous micro-reaction approach with high heat and mass transfer rates to synthesize few-layer MoS2 nanoplates with abundant active sites. The defective MoS2 ultrathin nanoplates exhibit excellent HER performance with an overpotential of 260 mV at a current density of 10 mA cm-2 small Tafel slope (53.6 mV dec-1) and prominent durability which are comparable to most reported MoS2 based catalysts. Considering the existence of continuous devices it’s suitable for the synthesis of MoS2 as high-performance electrocatalysts for the industrial water electrolysis. The novel preparation method may open up a new way to synthesize all two-dimension materials toward HER.

Hydrogen transportation systems require very high pressure hydrogen storage containers to enable sufficient vehicle range for practical use. Current proposed designs have pressures up to 70 MPa with leakage due to damage or deterioration at such high pressures a great safety concern. Accurate models are needed to predict the flammability envelopes around such leaks which rapidly vary with time. This paper compares CFD predictions of jet flows for low pressure jets with predictions using the integral turbulent buoyant jet model. The results show that the CFD model predicts less entrainment and that the turbulent Schmidt number should be smaller with 0.55 giving better results. Then CFD predictions for very high pressure flows are compared with analytical models for choked flows that generate underexpanded jets into the ambient to evaluate the effects of the model assumptions and the effects of real exit geometries. Real gas effects are shown to accelerate the blowdown process and that real flow effects in the CFD model slow the flow rate and increase the exit temperature.

Currently most of the vehicles make use of fossil fuels for operations resulting in one of the largest sources of carbon dioxide emissions. The need to cut our dependency on these fossil fuels has led to an increased use of renewable energy sources (RESs) for mobility purposes. A technical and economic analysis of a one-stop charging station for battery electric vehicles (BEV) and fuel cell electric vehicles (FCEV) is investigated in this paper. The hybrid optimization model for electric renewables (HOMER) software and the heavy-duty refueling station analysis model (HDRSAM) are used to conduct the case study for a one-stop charging station at Technical University of Denmark (DTU)-Risø campus. Using HOMER a total of 42 charging station scenarios are analyzed by considering two systems (a grid-connected system and an off-grid connected system). For each system three different charging station designs (design A-hydrogen load; design B-an electrical load and design C-an integrated system consisting of both hydrogen and electrical load) are set up for analysis. Furthermore seven potential wind turbines with different capacity are selected from HOMER database for each system. Using HDRSAM a total 18 scenarios are analyzed with variation in hydrogen delivery option production volume hydrogen dispensing option and hydrogen dispensing option. The optimal solution from HOMER for a lifespan of twenty-five years is integrated into design C with the grid-connected system whose cost was $986065. For HDRSAM the optimal solution design consists of tube trailer as hydrogen delivery with cascade dispensing option at 350 bar together with high production volume and the cost of the system was $452148. The results from the two simulation tools are integrated and the overall cost of the one-stop charging station is achieved which was $2833465. The analysis demonstrated that the one-stop charging station with a grid connection is able to fulfil the charging demand cost-effectively and environmentally friendly for an integrated energy system with RESs in the investigated locations.

Medium Mn steels have been considered as the next-generation materials for use in the automotive industry due to their excellent strength and ductility balance. To reduce the total weight and improve the safety of vehicles medium Mn steels look forward to a highly promising future. However hydrogen-induced delayed cracking is a concern for the use of high strength steels. This work is focused on the service characteristics of two kinds of medium Mn steels under different relative humidity conditions (40% 60% 80% and 100%). Under normal relative humidity (about 40%) at 25 °C the hydrogen concentration in steel is 0.4 ppm. When exposed to higher relative humidity the hydrogen concentration in steel increases slowly and reaches a stable value about 0.8 ppm. In slow strain rate tensile tests under different relative humidity conditions the tensile strength changed the hydrogen concentration increased and the elongation decreased as well thereby increasing the hydrogen embrittlement sensitivity. In other words the smaller the tensile rate applied the greater the hydrogen embrittlement sensitivity. In constant load tests under different relative humidity conditions the threshold value of the delayed cracking of M7B (‘M’ referring to Mn ‘7’ meaning the content of Mn ‘B’ denoting batch annealing) steel maintains a steady value of 0.82 σb (tensile strength). The threshold value of the delayed cracking of M10B significantly changed along with relative humidity. When relative humidity increased from 60% to 80% the threshold dropped sharply from 0.63 σb to 0.52 σb. We define 80% relative humidity as the ‘threshold humidity’ for M10B.