Japan

Reversible solid oxide cells (r-SOCs) can be operated in either solid oxide fuel cell or solid oxide electrolysis cell mode. They are expected to become important in the support of renewable energy due to their high efficiency for both power generation and hydrogen generation. The exchange current density is one of the most important parameters in the quantification of electrode performance in solid oxide cells. In this study four different fuel electrodes and two different air electrodes are fabricated using different materials and the microstructures are compared. The temperature fuel humidification and oxygen concentration at the air electrode are varied to obtain the apparent exchange current density for the different electrode materials. In contrast to ruthenium-and-gadolinia-doped ceria (Rh-GDC) as well as nickel-and-gadolinia-doped ceria (Ni-GDC) electrodes significant differences in the apparent exchange current density were observed between electrolysis and fuel cell modes for the nickel-scandia-stabilized zirconia (Ni-ScSZ) cermet. Variation of gas concentration revealed that surface adsorption sites were almost completely vacant for all these electrodes. The apparent exchange current densities obtained in this study are useful as a parameter for simulation of the internal properties of r-SOCs.

It is necessary to investigate cylinder crush behavior for improvement of fuel cell vehicle crash safety. However there have been few crushing behaviour investigations of high pressurized cylinders subjected to external force. We conducted a compression test of pressurized cylinders impacted by external force. We also investigated the cylinder strength and crushing behaviour of the cylinder. The following results were obtained.

• The crush force of high pressurized cylinders is different from the direction of external force. The lateral crush force of high pressurized cylinders is larger than the external axial crush force.
• Tensile stress occurs in the boundary area between the cylinder dome and central portion when the pressurized cylinder is subjected to axial compression force and the cylinder is destroyed.
• However the high pressurized cylinders tested had a high crush force which exceeded the assumed range of vehicle crash test procedures

For the evaluation of hydrogen and fuel cell vehicle safety a new comprehensive facility was constructed in our institute. The new facility includes an explosion resistant indoor vehicle fire test building and high pressure hydrogen tank safety evaluation equipment. The indoor vehicle fire test building has sufficient strength to withstand even an explosion of a high pressure hydrogen tank of 260 liter capacity and 70 MPa pressure. It also has enough space to observe vehicle fire flames of not only hydrogen but also other conventional fuels such as gasoline or compressed natural gas. The inside dimensions of the building are a 16 meter height and 18 meter diameter. The walls are made of 1.2 meter thick reinforced concrete covered at the insides with steel plate. This paper shows examples of hydrogen vehicle fires compared with other fuel fires and hydrogen high pressure tank fire tests utilizing several kinds of fire sources. Another facility for evaluation of high pressure hydrogen tank safety includes a 110 MPa hydrogen compressor with a capacity of 200 Nm3/h a 300 MPa hydraulic compressor for burst tests of 70 MPa and higher pressure tanks and so on. This facility will be used for not only the safety evaluation of hydrogen and fuel cell vehicles but also the establishment of domestic/international regulations codes and standards.

This study investigated a pre-cooled turbojet engine for a Mach 5 class hypersonic transport aircraft. The engine was demonstrated under takeoff and Mach 2 flight conditions and a Mach 5 propulsion wind tunnel test is planned. The engine is composed of a pre-cooler a core engine and an afterburner. The engine was tested under simulated Mach 4 conditions using an air supply facility. High-temperature air under high pressure was supplied to the engine components through an airflow control valve and an orifice flow meter and liquid hydrogen was supplied to the pre-cooler and the core engine. The results confirmed that the starting sequence of the engine components was effective under simulated Mach 4 conditions using liquid hydrogen fuel. The pre-cooling effect caused no damage to the rotating parts of the core engine in the experiment.

Hydrogen is one of the important alternative fuels for future transportation. At the present stage research into hydrogen safety and designing risk mitigation measures are significant task. For compact storage of hydrogen in fuel cell vehicles storage of hydrogen under high pressure up to 40 MPa at refuelling stations is planned and safety in handling such high-pressure hydrogen is essential. This paper describes our experimental investigation into dispersion of high-pressure hydrogen gas which leaks through pinholes in the piping to the atmosphere. First in order to comprehend the basic behaviour of the steady dispersion of high-pressure hydrogen gas from the pinholes the time-averaged concentrations were measured. In our experiments initial release pressures of hydrogen gas were set at 20 MPa or 40 MPa and release diameters were in the range from 0.25 mm to 2 mm. The experimental results show that the hydrogen concentration along the axis of the dispersion plume can be expressed as a simple formula which is a function of the downwind distance X and the equivalent release diameter. This formula enables us to easily estimate the axial concentration (maximum concentration) at each downstream distance. However in order for the safety of flammable gas dispersion to be analyzed comparisons between time-averaged concentrations evaluated as above and lower flammable limit are insufficient. This is because even if time-averaged concentration is lower than the flammability limit instantaneous concentrations fluctuate and a higher instantaneous concentration occasionally appears due to turbulence. Therefore the time-averaged concentration value which can be used as a threshold for assessing safety must be determined considering concentration fluctuations. Once the threshold value is determined the safe distance from the leakage point can be evaluated by the above-mentioned simple formula. To clarify the phenomenon of concentration fluctuations instantaneous concentrations were measured with the fast-response flame ionization detector. A small amount of methane gas was mixed into the hydrogen as a tracer gas for this measurement. The relationship between the time-mean concentration and the occurrence probability of flammable concentration was analyzed. Under the same conditions spark-ignition experiments were also conducted and the relationship between the occurrence probability of flammable concentration and actual ignition probabilities were also investigated. The experimental results show that there is a clear correlation between the time-mean concentration the occurrence probability of flammable concentration flame length and occurrence probability of hydrogen flame.

To identify the safety issues associated with hydrogen fuelling stations incidents at such stations in Japan and the USA were analyzed considering the regulations in these countries. Leakage due to the damage and fracture of main bodies of apparatuses and pipes in Japan and the USA is mainly caused by design error that is poorly planned fatigue. Considering the present incidents in these countries adequate consideration of the usage environment in the design is very important. Leakage from flanges valves and seals in Japan is mainly caused by screw joints. If welded joints are to be used in hydrogen fuelling stations in Japan strength data for welded parts should be obtained and pipe thicknesses should be reduced. Leakage due to other factors e.g. external impact in Japan and the USA is mainly caused by human error. To realize self-serviced hydrogen fuelling stations safety measures should be developed to prevent human error by fuel cell vehicle users.

This paper shows the numerical investigation on the self-ignition behavior of high pressure hydrogen released from the tube. The present study aims to clarify the effect of parameters on the behavior and duration of self-ignition outside the tube using two-dimensional axisymmetric numerical simulation with detailed chemistry. The parameters in this study are release pressure tube diameter and tube length. The strength of the spherical shock wave to keep chemical reaction and expansion are important factors for self ignited hydrogen jet to be sustained outside the tube. The trend of strength of spherical shock wave is enhanced by higher release pressure and larger tube diameter. The chemical reaction weakens due to expansion and the degree of expansion becomes larger as the spherical shock wave propagates. The characteristic time for the chemical reaction becomes shorter in higher release pressure larger tube diameter and longer tube diameter cases from the induction time under constant volume assumption. The self ignited hydrogen jet released from the tube is sustained up to the distance where the characteristic time for chemical reaction is shorter than the characteristic time for the flow to expand and higher release pressure larger tube diameter and longer tube length expand the distance where the tip flame can propagate downstream. For the seed flame which is the key for jet fire the larger amount of the ignited volume when the shock wave reaches the tube exit contributes to the formation and stability of the seed flame. The amount of the ignited volume tends to be larger in the longer tube length higher release pressure and larger tube diameter cases.

Although many studies have looked at safety issues relating to hydrogen fuelling stations few studies have analyzed the security risks such as deliberate attack of the station by threats such as terrorists and disgruntled employees. The purpose of this study is to analyze security risks for a hydrogen fuelling station with an on-site production of hydrogen from methylcyclohexane. We qualitatively conducted a security risk analysis using American Petroleum Institute Standard 780 as a reference for the analysis. The analysis identified 93 scenarios including pool fires. We quantitatively simulated a pool fire scenario unique to the station to analyze attack consequences. Based on the analysis and the simulation we recommend countermeasures to prevent and mitigate deliberate attacks.

The hydrogen permeation coefficient (ϕ) is generally used as a measure to show hydrogen permeation ability through dense metallic membranes which is the product of the Fick’s diffusion coefficient (D) and the Sieverts’ solubility constant (K). However the hydrogen permeability of metal membranes cannot be analyzed consistently with this conventional description. In this paper various methods for consistent analysis of hydrogen permeability are reviewed. The derivations of the descriptions are explained in detail and four applications of the consistent descriptions of hydrogen permeability are introduced: (1) prediction of hydrogen flux under given conditions (2) comparability of hydrogen permeability (3) understanding of the anomalous temperature dependence of hydrogen permeability of Pd-Ag alloy membrane and (4) design of alloy composition of non-Pd-based alloy membranes to satisfy both high hydrogen permeability together with strong resistance to hydrogen embrittlement.

This paper addresses from both macro- and micro- areal coverage in introducing hydrogen system in terms of cost and performance where the produced hydrogen from surplus photovoltaic (PV) power is stored. Feed-in tariff in Japan had successful achievement for great expansion of renewable energy systems (RES) causing problematic operation due to excess power by overcapacity of RES. One of the candidate approaches to overcome this surplus energy by RES is Power to gas (P2G) system using electrolysis cells (ECs) fuel cells (FCs) or co-firing in gas turbines both for energy conversion as well as power balancing. Numerous studies had been investigated on P2G however within our knowledge no study had been addressed the system from both coverages with different capacity and scales. We investigate micro level (zero emission building in our university) and macro level (Kyushu one of big regions in Japan). We describe for macro side preliminary result on economic analysis of using surplus power of RES via production and storage of hydrogen while for micro side research design.

Ductile cast iron (DCI) is one of prospective materials used for the hydrogen equipment because of low-cost good workability and formability. The wide range of mechanical properties of DCI is obtained by controlling microstructural factors such as graphite size volume fraction of graphite matrix structure and so on. Therefore it is important to find out an optimal microstructural condition that is less susceptible to hydrogen embrittlement. In this study the effects of graphite size on the hydrogen absorption capability and the hydrogen-induced ductility loss of ferritic DCI were investigated.<br/>Several kinds of ferritic DCIs with a different graphite diameter of about 10 µm - 30 µm were used for the tensile test and the hydrogen content measurement. Hydrogen charging was performed prior to the tensile test by exposing a specimen to high-pressure hydrogen gas. Then the tensile test was performed in air at room temperature. The hydrogen content of a specimen was measured by a thermal desorption analyzer.<br/>It was found that the amount of hydrogen stored in DCI was dependent on the graphite size. As the graphite diameter increased the hydrogen content sharply increased at a certain graphite diameter and then it became nearly constant irrespective of increase in graphite diameter. In other words there was the critical graphite diameter that significantly changed the hydrogen absorption capability. The ductility was decreased by hydrogen and the hydrogen-induced ductility loss was dependent on the hydrogen content. Therefore the hydrogen embrittlement of DCI became remarkable when the graphite size was larger than the critical value.

The states of Regulations Codes and Standards (RCS) of hydrogen refueling stations (HRSs) in Japan and France are compared and specified items to understand correspondence and differences among each RCSs for realizing harmonization in RCS. Japan has been trying to reform its RCSs to reduce HRS installation and operation costs as a governmental target. Specific crucial regulatory items such as safety distances mitigation means materials for hydrogen storage and certification of anti-explosion proof equipments are compared in order to identify the origins of the current obstacles for disseminating HRS.

Hydrogen leakage in a closed space is one of the causes of serious accidents because of its high detonability. Assuming the situation that hydrogen is accumulated in a closed space two-dimensional numerical simulation for hydrogen oxygen detonation which propagates in stratified fuel and oxidizer with concentration gradient is conducted by using detailed chemical reaction model. The concentration gradient between fuel and oxidizer is expressed by changing the number of hydrogen moles by using sigmoid function. Strength of discontinuity at the boundary is controlled by changing the gain of the function. The maximum pressure history shows that the behaviour of triple points is different depending on the strength of discontinuity between the two kind of gas. In without concentration gradient case the transverse waves are reflected at the boundary because of the sudden change of acoustic impedance ratio between two kind of gas. In contrast in with concentration gradient case the transverse wavs are not reflected in the buffer zone and they are flowed into the oxidizer as its structures are kept. As a result the confined effect declines as the strength of discontinuity between the two kind of gas is weakened and the propagating distance of detonation changes

Hydrogen has emerged as an important part of the clean energy mix needed to ensure a sustainable future. Falling costs for hydrogen produced with renewable energy combined with the urgency of cutting greenhouse-gas emissions has given clean hydrogen unprecedented political and business momentum.



This paper from the International Renewable Energy Agency (IRENA) examines the potential of hydrogen fuel for hard-to-decarbonise energy uses including energy-intensive industries trucks aviation shipping and heating applications. But the decarbonisation impact depends on how hydrogen is produced. Current and future sourcing options can be divided into grey (fossil fuel-based) blue (fossil fuel-based production with carbon capture utilisation and storage) and green (renewables-based) hydrogen. Green hydrogen produced through renewable-powered electrolysis is projected to grow rapidly in the coming years.



Among other findings:



Important synergies exist between hydrogen and renewable energy. Hydrogen can boost renewable electricity market growth and broaden the reach of renewable solutions.

• Electrolysers can add demand-side flexibility. In advanced European energy markets electrolysers are growing from megawatt to gigawatt scale.
• Blue hydrogen is not inherently carbon free. This type of production requires carbon-dioxide (CO2) monitoring verification and certification.
• Synergies may exist between green and blue hydrogen deployment given the chance for economies of scale in hydrogen use or logistics.
• A hydrogen-based energy transition will not happen overnight. Hydrogen use is likely to catch on for specific target applications. The need for new supply infrastructure could limit hydrogen use to countries adopting this strategy.
• Dedicated hydrogen pipelines have existed for decades and could be refurbished along with existing gas pipelines. The implications of replacing gas abruptly or changing mixtures gradually should be further explored.

Trade of energy-intensive commodities produced with hydrogen including “e-fuels” could spur faster uptake or renewables and bring wider economic benefits.

Multiple-energy-fuelling stations which can supply several types of energy such as gasoline CNG and hydrogen could guarantee the efficient use of space. To guide the safety management of hybrid hydrogen–gasoline fuelling stations which utilize liquid hydrogen as an energy carrier the scale of gasoline pool fires was estimated using the hazard assessment tool Toxic Release Analysis of Chemical Emissions (TRACE). Subsequently the temperature and the stress due to temperature distribution were estimated using ANSYS. Based on the results the safety of liquid hydrogen storage tanks was discussed. It was inferred that the emissivity of the outer material of the tank and the safety distance between liquid hydrogen storage tanks and gasoline dispensers should be less than 0.2 and more than 8.5 m respectively to protect the liquid hydrogen storage tank from the gasoline pool fire. To reduce the safety distance several measures are required e.g. additional thermal shields such as protective intumescent paint and water sprinkler systems and an increased slope to lead gasoline off to a safe domain away from the liquid hydrogen storage tank

Hydrogen intrudes into the steel during pickling process which is a pre-processing before a joining process promoting crack formation. In a mechanical clinching which is one of joining method in the automotive industry cracks due to large strain sometimes forms. In order to guarantee reliability it is important to clarify the influence of hydrogen on crack formation of the joint. In this study we clarified the influence of hydrogen for the crack formation on the mechanical clinching. Hydrogen charge was carried out using an electrolytic cathode charge. After the charging mechanical clinching was performed. Mechanical clinching was carried out with steel plate and aluminium alloy plate. To clarify the influence of hydrogen mechanical clinching was conducted without hydrogen charring. To investigate the crack formation the test piece was cut and the cut surface was observed. When the joint was broken during the clinching the fracture surface was observed using an optical microscope and an electron microscope. The load-displacement diagram showed that without hydrogen charging the compressive load increased as the displacement increased. On the other hand the compressive load temporarily decreased with high hydrogen charging suggesting that cracks formed at the time. The cut surface observation showed that interlock was formed in both cases with low hydrogen charging and without hydrogen charging. With low hydrogen charging no cracks were formed in the joint. When high hydrogen charging was performed cracks were formed at the joining point. Fracture analysis showed brittle-like fracture surface. These results indicate that hydrogen induces crack formation in the mechanical clinching.

Effects of hydrogen on slow-strain-rate tensile (SSRT) and fatigue-life properties of 17-4PH H1150 martensitic stainless steel having an ultimate tensile strength of ~1GPa were investigated. Smooth and circumferentially-notched axisymmetric specimens were used for the SSRT and fatigue-life tests respectively. The fatigue-life tests were done to investigate the hydrogen effect on fatigue crack growth (FCG) properties. The specimens tested in air at ambient temperature were precharged by exposure to hydrogen gas at pressures of 35 and 100 MPa at 270°C for 200 h. The SSRT properties of the H-charged specimens were degraded by hydrogen showing a relative reduction in area (RRA) of 0.31 accompanied by mixed fracture surfaces composed of quasi-cleavage (QC) and intergranular cracking (IG). The fatigue-life tests conducted under wide test frequencies ranging from 10-3 Hz to 10 Hz revealed three distinct characteristics in low- and high-cycle regimes and at the fatigue limit. The fatigue limit was not degraded by hydrogen. In the high-cycle regime the hydrogen caused FCG acceleration with an upper bound ratio of 30 accompanied by QC surfaces. In the low-cycle regime the hydrogen caused FCG acceleration with a ratio of ~100 accompanied by QC and IG. The ordinary models such as process competition and superposition models hardly predicted the H-assisted FCG acceleration; therefore an interaction model successfully reproducing the experimental FCG acceleration was newly introduced.

The presented research focuses on an optimization design of a catalyst distribution inside a small-scale methane/steam reforming reactor. A genetic algorithm was used for the multiobjective optimization which included the search for an optimum of methane conversion rate and a minimum of the difference between highest and lowest temperatures in the reactor. For the sake of computational time the maximal number of the segment with different catalyst densities was set to be thirty in this study. During the entire optimization process every part of the reactor could be filled either with a catalyst material or non-catalytic metallic foam. In both cases the porosity and pore size was also specified. The impact of the porosity and pore size on the active reaction surface and permeability was incorporated using graph theory and three-dimensional digital material representation. Calculations start with the generation of a random set of possible reactors each with a different catalyst distribution. The algorithm calls reforming simulation over each of the reactors and after obtaining concentration and temperature fields the algorithms calculated fitness function. The properties of the best reactors are combined to generate a new population of solutions. The procedure is repeated and after meeting the coverage criteria the optimal catalyst distribution was proposed. The paper is summarized with the optimal catalyst distribution for the given size and working conditions of the system.

In this paper a multifunctional energy system (MES) is proposed for recovering energy from the extra of coke oven gas (COG) which is usually flared or vented out as a waste stream in coke making plants. The proposed system consists of a pressure swing adsorption (PSA) unit for extracting some of the hydrogen from COG a gas turbine for producing heat and power from PSA offgas and a heat recovery steam generator (HRSG) for generating the steam required by the plant's processes. o assess the performance of the system practically simulations are carried out on the basis of the design and operational conditions of Zarand Coke Making Plant in Iran. The results indicate that by utilizing about 4.39 tons of COG per hour 6.5 MW of net electric power can be approximately produced by the gas turbine which can supply the coke making plant's total electrical power demand. Furthermore through recovering heat from gas turbine's exhaust close to 57% of the plant's steam demand can be supplied by the HRSG unit. It is also found that around 350 kilograms per hour of nearly pure hydrogen (99.9% purity) at 200 bar can be produced by the PSA unit. According to the sensitivity analysis results if the hydrogen content of the coke oven gas decreases by about 10% the gross power output of the gas turbine also declines by around 5.2% due to the reduction of LHV of the PSA offgas. Moreover economic evaluation of the system shows that the payback period of the investment which is estimated at 36.1 M$ is about 5.5 years. The net present value (NPV) and internal rate of return on investment (ROI) are calculated to be 17.6% and 43.3 M$ respectively.

Hydrogen is a promising energy carrier in the clean energy systems currently being developed. However its effectiveness in mitigating greenhouse gas (GHG) emissions requires conducting a lifecycle analysis of the process by which hydrogen is produced and supplied. This study focuses on the hydrogen for the transport sector in particular renewable hydrogen that is produced from wind- or solar PV-powered electrolysis. A life cycle inventory analysis is conducted to evaluate the Well-to-Tank (WtT) GHG emissions from various renewable hydrogen supply chains. The stages of the supply chains include hydrogen being produced overseas converted into a transportable hydrogen carrier (liquid hydrogen or methylcyclohexane) imported to Japan by sea distributed to hydrogen filling stations restored from the hydrogen carrier to hydrogen and filled into fuel cell vehicles. For comparison an analysis is also carried out with hydrogen produced by steam reforming of natural gas. Foreground data related to the hydrogen supply chains are collected by literature surveys and the Japanese life cycle inventory database is used as the background data. The analysis results indicate that some of renewable hydrogen supply chains using liquid hydrogen exhibited significantly lower WtT GHG emissions than those of a supply chain of hydrogen produced by reforming of natural gas. A significant piece of the work is to consider the impacts of variations in the energy and material inputs by performing a probabilistic uncertainty analysis. This suggests that the production of renewable hydrogen its liquefaction the dehydrogenation of methylcyclohexane and the compression of hydrogen at the filling station are the GHG-intensive stages in the target supply chains.

Energies based on biomaterials attract a lot of interest as next-generation energy because biomaterials are environmentally friendly materials and abundant in nature. Fuel cells are also known as the clean and important next-generation source of energy. In the present study to develop the fuel cell based on biomaterials a novel biofuel cell which consists of collagen electrolyte and the hydrogen fuel generated from photochemical system II (PSII) in photosynthesis has been fabricated and its property has been investigated. It was found that the PSII solution in which PSII was extracted from the thylakoid membrane using a surfactant generates hydrogen by the irradiation of light. The typical hydrogen-generating rate is approximately 7.41 × 1014 molecules/s for the light intensity of 0.5 mW/cm2 for the PSII solution of 5 mL. The biofuel cell using the PSII solution as the fuel exhibited approximately 0.12 mW/cm2 . This result indicates that the fuel cell using the collagen electrolyte and the hydrogen fuel generated from PSII solution becomes the new type of biofuel cell and will lead to the development of the next-generation energy

The utilization of hydrogen energy is important for achieving a low-carbon society. Japan has set ambitious goals for hydrogen stations and fuel cell vehicles focusing on the introduction and dissemination of self-refuelling systems. This paper evaluates public trust in the fuel equipment and self-handling technology related to self-refuelling hydrogen stations and compares it with that for widespread gasoline stations. To this end the results of an online survey of 300 people with Japanese driver licenses are reported and analyzed. The results show that trust in the equipment and self-handling is more important for the user than trust in the fuel. In addition to introduce and disseminate new technology such as hydrogen stations users must be made aware of the risk of using the technology until it becomes as familiar as existing gasoline station technology.

To understand hydrogen uptake in porous carbon materials we developed machine learning models to predict excess uptake at 77 K based on the textural and chemical properties of carbon using a dataset containing 68 different samples and 1745 data points. Random forest is selected due to its high performance (R² > 0.9) and analysis is performed using Shapley Additive Explanations (SHAP). It is found that pressure and Brunauer-Emmett-Teller (BET) surface area are the two strongest predictors of excess hydrogen uptake. Surprisingly this is followed by a positive correlation with oxygen content contributing up to ∼0.6 wt% additional hydrogen uptake contradicting the conclusions of previous studies. Finally pore volume has the smallest effect. The pore size distribution is also found to be important since ultramicropores (dp < 0.7 nm) are found to be more positively correlated with excess uptake than micropores (d_p < 2 nm). However this effect is quite small compared to the role of BET surface area and total pore volume. The novel approach taken here can provide important insights in the rational design of carbon materials for hydrogen storage applications.

Hydrogen fuel cell vehicles are expected to play an important role in the future and thus have improved significantly over the past years. Hydrogen fuel cell motorcycles with a small container for compressed hydrogen gas have been developed in Japan along with related regulations. As a result national regulations have been established in Japan after discussions with Japanese motorcycle companies stakeholders and experts. The concept of Japanese regulations was proposed internationally and a new international regulation on hydrogen-fueled motorcycles incorporating compressed hydrogen storage systems based on this concept are also established as United Nations Regulation No. 146. In this paper several technical regulations on hydrogen safety specific to fuel cell motorcycles incorporating compressed hydrogen storage systems are summarized. The unique characteristics of these motorcycles e.g. small body light weight and tendency to overturn easily are considered in these regulations.

In order for fuel cell vehicles to develop a widespread role in society it is essential that hydrogen refuelling stations become established. For this to happen there is a need to demonstrate the safety of the refuelling stations. The work described in this paper was carried out to provide experimental information on hydrogen outflow dispersion and explosion behaviour. In the first phase homogeneous hydrogen-air-mixtures of a known concentration were introduced into an explosion chamber and the resulting flame speed and overpressures were measured. Hydrogen concentration was the dominant factor influencing the flame speed and overpressure. Secondly high-pressure hydrogen releases were initiated in a storage room to study the accumulation of hydrogen. For a steady release with a constant driving pressure the hydrogen concentration varied as the inlet airflow changed depending on the ventilation area of the room the external wind conditions and also the buoyancy induced flows generated by the accumulating hydrogen. Having obtained this basic data the realistic dispersion and explosion experiments were executed at full-scale in the hydrogen station model. High-pressure hydrogen was released from 0.8-8.0mm nozzle at the dispenser position and inside the storage room in the full-scale model of the refuelling station. Also the hydrogen releases were ignited to study the overpressures that can be generated by such releases. The results showed that overpressures that were generated following releases at the dispenser location had a clear correlation with the time of ignition distance from ignition point.