Safety

Numerical experiments are performed to understand different regimes of hydrogen non-premixed combustion in an enclosure with passive ventilation through one horizontal or vertical vent located at the top of a wall. The Reynolds averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) model with a reduced chemical reaction mechanism is described in detail. The model is based on the renormalization group (RNG) k-ε turbulence model the eddy dissipation concept (EDC) model for simulation of combustion coupled with the 18-step reduced chemical mechanism (8 species) and the in-situ adaptive tabulation (ISAT) algorithm that accelerates the reacting flow calculations by two to three orders of magnitude. The analysis of temperature and species (hydroxyl hydrogen oxygen water) concentrations in time as well as the velocity through the vent shed a light on regimes and dynamics of indoor hydrogen fires. A well-ventilated fire is simulated in the enclosure at a lower release flow rate and complete combustion of hydrogen within the enclosure. Fire becomes under-ventilated at higher release flow rates with two different modes observed. The first mode is the external flame stabilised at the enclosure vent at moderate release rates and the second mode is the self-extinction of combustion inside and outside the enclosure at higher hydrogen release rates. The simulations demonstrated a complex reacting flow dynamics in the enclosure that leads to formation of the external flame or the self-extinction. The air intake into the enclosure at later stages of the process through the whole vent area is a characteristic feature of the self-extinction regime. This air intake is due to faster cooling of hot combustion products by sustained colder hydrogen leak compared to the generation of hot products by the ceasing chemical reactions inside the enclosure and hydrogen supply. In general an increase of hydrogen sustained release flow rate will change fire regime from the well-ventilated combustion within the enclosure through the external flame stabilised at the vent and finally to the self-extinction of combustion throughout the domain.

A better understanding of chemical kinetics under volumetric expansion is important for a number of situations relevant to industrial safety including detonation diffraction and direct initiation reflected shock-ignition at obstacles ignition behind a decaying shock among others. The ignition of stoichiometric hydrogen-air mixtures was studied using 0D numerical simulations with time-dependent specific volume variations. The competition between chemical energy release and expansion-induced cooling was characterized for different cooling rates and mathematical forms describing the shock decay rate. The critical conditions for reaction quenching were systematically determined and the thermo-chemistry dynamics were analyzed near the critical conditions.

Despite hydrogen is one of the most suitable candidates in replacing fossil fuels its very low densityrepresents a drawback when it is stored. The liquefaction process can increase the hydrogen densityand therefore enhance its storage capacity. The boiling liquid expanding vapour explosion (BLEVE) isa typical accident scenario that must be always considered when liquefied gases are stored. Inparticular BLEVE is a physical explosion with low probabilities and high consequences which mayoccur after the catastrophic rupture of a vessel containing a liquid with a temperature above its boilingpoint at atmospheric pressure. In this paper a parametric CFD analysis of the BLEVE phenomenonwas conducted by means of the CFD code ADREA-HF for liquid hydrogen (LH2) vessels. Firstly theCFD model is validated against a well-documented CO2 BLEVE experiment. Next hydrogen BLEVEcases are examined. The physical parameters were chosen based on the BMW tests carried out in the1990s on LH2 tanks designed for automotive purposes. Different filling degrees initial pressures andtemperatures of the tank content are simulated to comprehend how the blast wave is influenced by theinitial conditions. The aim of this study is twofold: provide new insights and observations on theBLEVE dynamics and demonstrate the CFD tool effectiveness for conducting the consequenceanalysis and thus aiding the risk assessment of liquefied gas vessel explosion. Good agreement wasshown between the simulation outcomes and the experimental results.

Energy production by methanization or gasification of biomass is dependant on the chemical composition of the gas generated. The resistive sensors based on semiconductor metal oxides like the MQ series sensors are inexpensive and frequently used in gas detection. These sensors initially dedicated to detecting gas leaks in safety systems have relatively small measurement ranges (i.e. limited to concentrations below 10000 ppm). It is therefore necessary to find solutions to adapt these categories of sensors for gas measurements in the energy sector where the gas concentration is much more significant. In this article we propose a protocol using an adaptable capsule for MQ-4 and MQ-8 sensors to measure high concentrations of CH4 and H2 respectively. The technique consists of diluting the gas to be studied in a known volume of air. Three methods are proposed and compared regarding the linearity and the repeatability of the measurements. The first method was done in an airtight enclosed chamber the second method consists of directly injecting the gas on the sensor placed in an open environment and the final method was accomplished by direct injection of the gas on the sensor placed in a partially closed capsule. Comparisons show that the first technique provides the best repeatability with a maximum standard deviation of 13.88% for CH4 measurement and 5.1% for H2. However its linearity is weak (i.e. R2 ¼ 0.8637 for CH4 and R2 ¼ 0.5756 for H2). The second technique has better linearity but bad repeatability. The third technique presents the best results with R2 values of 0.9973 for the CH4 measurement and 0.9472 for H2. The use of the partially closed capsule resulted in an acceptable linear response of the sensors by up to 20% concentration of CH4 and until 13.33% concentration of H2 in the studied gas. The use of this simple and low-cost technique facilitates the characterization of combustible gases in isolated areas. It allows local operators of biomass valorization systems to control and improve their installations while avoiding the high costs of conventional measurement devices. This study hence contributes to the development of rural electrification projects in remote areas.

Adding hydrogen to mains natural gas has been identified as one of the main strategies to reduce CO2 emissions in the United Kingdom. This work aims to characterise the explosion severity of 80:20 v./v. methane/hydrogen blends (‘a blend’) and methane vented deflagrations. The explosion severity of homogenous mixtures was measured in a 15 m3 cubic steel chamber in which the relief area was provided by four windows and a door covered with polypropylene sheet. The pressure increase over time was characterised using piezo-resistive pressure transducers and the flame speed was estimated using ionisation probes installed in the walls of the enclosure. The explosion severity of both mixtures was determined for different equivalence ratios from lean to rich mixtures. The pressure over time presented very similar behaviour for both mixtures comprising multiple peaks divided into three main stages: a first stage related to a spherical confined explosion until the opening of the vent a second stage generated by increased combustion during venting and an oscillatory peak generated by acoustic disturbances with the enclosure. A slight increase in the first stage overpressure was observed for the blend in comparison with methane regardless of the equivalence ratio but no general trend in pressure was observed for other stages of the propagation. The effect of the blockage ratio on explosion severity was studied by adding metallic elements representing furniture in a room.

Blending hydrogen into ammonia can I mprove the burning intensity of ammonia and the safety of hydrogen and it is important to understand the flames of NH3/H2/air mixtures. In this work lamiar flame characteristics of 50-50 (vol%) ammonia-hydrogen mixtures in air were studied using the spherical flame propagation method in a constant-volume bom at initital temperature Tu = 298K and different pressures.

Hydrogen jet fires from a thermally activated pressure relief device (TPRD) on onboard storage are considered for a vehicle in a naturally ventilated covered car park. Computational Fluid Dynamics was used to predict behaviour of ignited releases from a 70 MPa tank into a naturally ventilated covered car park. Releases through TPRD diameters 3.34 2 and 0.5 mm were studied to understand effect on hazard distances from the vehicle. A vertical release and downward releases at 0° 30° and 45° for TPRD diameters 2 and 0.5 mm were considered accounting for tank blowdown. direction of a downward release was found to significantly contribute to decrease of temperature in a hot cloud under the ceiling. Whilst the ceiling is reached by a jet exceeding 300 °C for a release through a TPRD of 2 mm for inclinations of either 0° 30° or 45° an ignited release through a TPRD of 0.5 mm and angle of 45° did not produce a cloud with a temperature above 300 °C at the ceiling during blowdown. The research findings specifically regarding the extent of the cloud of hot gasses have implications for the design of mechanical ventilation systems.

With the growing success of green hydrogen the general trend is for increased hydrogen production and large quantities of storage. Engie’s projects have grown from a few kilos of hydrogen to the quest for large scale production and associated storage – e.g. several tons or tens of tons. Although a positive sign for Engie’s projects it does inevitably result in challenges in new storage methods and in risks management related to such facilities; particularly with hydrogen facilities being increasingly placed in the vicinity of general public sites. For example a leak on hydrogen storage can generate significant thermal and overpressure effects on surrounding people/facilities in the event of ignition. Firewalls can be installed to protect individuals / infrastructure from thermal effects but the adverse result is that this solution can increase the violence of an explosion in case of delayed ignition or confinement. The manner of emergency intervention on a pool fire of hydrogen is also totally different from intervention on compressed gaseous hydrogen. The first part of this presentation will explain different means to store hydrogen in large quantities. The second part will present for each storage the specific risks generated. The third and final part will explain how these risks can be addressed on a technical point of view by safety devices or by other solutions (separation distance passive/active means …).

The European Community requires a vehicle-level bonfire test for vehicles using plastic fuel tanks for conventional fuels (ECE R-34 Annex 5). A similar test could be applied to hydrogen-fuelled vehicles. It would test a realistic vehicle with its complete fuel and safety systems. An advantage of such a test is that the same test could be applied independent of the hydrogen storage technology (compressed gas liquid or hydride). There are currently standards for bonfire testing of a bare Compressed Natural Gas (CNG) tank and its Pressure Relief Device (PRD). This standard is FMVSS 304 in the U.S. and ISO 15869-1 in Europe. Japan has a similar standard. It requires that a bare tank and its associated PRD be subjected to a propane flame for 20 minutes. The tank must either survive or safely vent its contents. No modern composite wound tank is expected to survive for 20 minutes – so this is not a tank test but really a PRD test. The test procedure requires the PRD to be shielded from direct impingement of the flames – but the shield is not well specified. If it shields the PRD too well the PRD will not activate and the tank will burst. This paper describes the results of a CNG and a hydrogen tank burst from such tests. The mechanical energy released is enormous. It is simply unacceptable to allow the tank to burst – the PRD and venting system must work. Organizations in the U.S Europe and Japan are in the process of modifying the CNG tank bonfire test for compressed hydrogen storage. A bare tank with a single PRD is not a good simulation of a hydrogen fuel system installed in an actual vehicle. There will usually be multiple tanks plumbed together at either the tank pressure or at the intermediate pressure (after the pressure regulator). There may be more than one PRD. The tank may be shielded (from debris) or insulated to protect it from an underbody pool fire. Also the heat transfer from the simulated pool fire (propane flame) will be very different when mounted in a vehicle versus the bare tank test. A vehicle-level pool fire test will alleviate these problems. It is therefore recommended that the bare tank test be replaced by or augmented with a vehicle-level bonfire test similar to ECE R-34 Annex 5.

This paper presents an experimental study of a hydrogen fusible link developed for use in the detection of hydrogen and in the activation of passive ventilation or other safety systems. Fusible links are commonly used to passively close fire dampers in the event of a fire; they generally consist of two pieces of metal joined together by a low temperature alloy to form a single device. When exposed to fire the link will heat up and eventually melt the alloy causing the metal pieces to separate. The same principle has been adopted for the hydrogen fusible link in which hydrogen recombiner catalyst was coated onto small rectangular brass plates. These plates were then soldered together to create prototypes of the hydrogen fusible link. When the resulting link is exposed to a hydrogen-air mixture an exothermic reaction occurs on the catalyst surface that will heat up the link and melt the solder separating the two sections of the hydrogen fusible link. A series of experiments was performed to characterize the thermal response of the hydrogen fusible links to various hydrogen-air mixtures. The effect of both hydrogen concentration and its rate of accumulation on the increase of catalyst temperature was examined. This study demonstrated the applicability of the hydrogen fusible link for managing hydrogen risk.

Dynamic overpressures achieved during the combustion are related to the acceleration experienced by the propagating flame. In the case of premixed turbulent combustion in an obstructed geometry obstacles in the direction of flow result in a complex flame front interaction with the turbulence generated ahead of it. The interaction of flame front and vortex significantly affect the burning rate the rate of pressure rise and achieved overpressure the geometry of accelerating flame front and resulting structures in the flow field. Laboratory-scale premixed turbulent combustion experiments are convenient for the study of flame acceleration by obstacles in higher resolution. This paper presents numerical simulations of hydrogenair mixture combustion experiments performed in the University of Sydney small-scale combustion chamber. The simulations were performed using flameFoam – an open-source premixed turbulent combustion solver based on OpenFOAM. The experimental and numerical pressure evolutions are compared. Furthermore flow structures which develop due to the interaction between the obstacles and the flow are investigated with different obstacle configurations.

Liquid hydrogen has the potential to form part of the energy strategy in the future due to the need to decarbonise and replace fossil fuels and therefore could see widespread use. Adoption of LH2 means that the associated hazards need to be understood and managed. In recognition of this the European Union Fuel Cells and Hydrogen Joint Undertaking co-funded project PRESLHY undertook prenormative research for the safe use of cryogenic liquid hydrogen in non-industrial settings. Several key scenarios were identified as knowledge gaps and both theoretical and experimental studies were conducted to provide insight into these scenarios. This included experiments studying the evolution/dispersion of a hydrogen cloud following a liquid release and the generation of electrostatic charges in hydrogen plumes and pipework each of which are described and discussed. In addition assessment of the physical phase of the hydrogen flow within the pipework (i.e. liquid gas or two phase) was investigated. The objectives experimental set up and result summary are provided. Data generated from these experiments is to be used to generate and validate theoretical models and ultimately contribute to the development of regulations codes and standards for the storage handling and use of liquid hydrogen.

The hydrogen dispersion phenomenon in an enclosure depends on the ratio of the gas buoyancy induced momentum. Random diffusive motions of individual gas particles become dominative when the release momentum is low. Then a uniform hydrogen concentration appears in the enclosure instead of the gas stratification below the ceiling. The paper justifies this hypothesis by demonstrating fullscale experimental results of hydrogen dispersion within a confined space under six different release variations. During the experiments hydrogen was released into the test room of 60 m3 volume in two methods: through a nozzle and through 21 points evenly distributed on the emission box cover (multipoint release). Each release method was tested with three different hydrogen volume flow rates (3.17·10−3 m3/s 1.63·10−3 m3/s 3.34·10−4 m3/s). The tests confirm the increase of hydrogen convective upward flow and its stratification tendency relative to increased volume flow. A tendency of more uniform hydrogen cloud distribution when Mach Reynolds and Froud number values decreased was demonstrated. Because the hydrogen dispersion phenomena impact fire and explosive hazards the presented experimental results could help fire protection systems be in an enclosure designed allowing their effectiveness optimization.

Hydrogen refueling stations are one of the key infrastructure components for the hydrogen-fueled economy. Skid-mounted hydrogen refueling stations (SHRSs) can be more easily commercialized due to their smaller footprints and lower costs compared to stationary hydrogen refueling stations. The present work modeled hydrogen explosions in a skid-mounted hydrogen refueling station to predict the overpressures for hydrogen-air mixtures and investigate the protective effects for different explosion vent layouts and protective wall distances. The results show that the explosive vents with the same vent area have similar overpressure reduction effects. The layout of the explosion vent affects the flame shape. Explosion venting can effectively reduce the inside maximum overpressure by 61.8%. The protective walls can reduce the overpressures but the protective walls should not be too close to the SHRS because high overpressures are generated inside the walls due to the confined shock waves. The protective wall with a distance of 6 m can effectively protect the surrounding people and avoid the secondary overpressure damage to the container.

Due to practical computational resource limits current simulations of premixed turbulent combustion experiments are often performed using simplified turbulence treatment. From all available RANS models k-ε and k-ω SST are the most widely used. k-ω SST model is generally expected to be more accurate in bounded geometries since it corresponds to k-ε model further from the walls but switches to more appropriate k-ω model near the walls. However k-ε is still widely used and in some instances is shown to provide better results. In this paper we perform RANS simulations of premixed hydrogen flame propagation in an acceleration tube using k-ε and k-ω SST models. Accuracy of the models is assessed by comparing obtained results with the experiment. In order to better understand differences between k-ε and k-ω-SST results parameters of main k-ω-SST model features are examined. The distribution of the blending functions values and corresponding zones of are analysed in relation to flame position and resulting observed propagation velocity. We show that in the simulated case biggest difference between k-ω-SST and k-ε model results can be attributed to turbulent eddy viscosity limiting by shear strain rate in the k-ω-SST model.

In the context of a numerical investigation of thermal hazards from two under-expanded hydrogen jet fires results from a newly-developed thermal radiation module of the ADREA-HF computational fluid dynamics (CFD) code were validated against two physical experiments. The first experiment was a vertical under-expanded hydrogen jet fire at 170 bar with the objective of the numerical investigation being to capture the spatial distribution of the radial radiative heat flux at a given time instant. In the second case a horizontal under-expanded hydrogen jet fire at 340 bar was considered. Here the objective was to capture the temporal evolution of the radial radiative heat flux at selected fixed points in space. The numerical study employs the eddy dissipation model for combustion and the finite volume method (FVM) for the calculation of the radiative intensity. The FVM was implemented using a novel angular discretization scheme. By dividing the unit sphere into an arbitrary number of exactly equal angular control volumes this new scheme allows for more flexibility and efficiency. A demonstration of numerical convergence as a function the number of both spatial and angular control volumes was performed.

The aim of this study is to assess numerically the influence of terrain landscape on the distribution of probable harmful consequences to personnel of hydrogen fueling station caused by an accidentally released and exploded hydrogen. In order to extract damaging factors of the hydrogen explosion wave (maximum overpressure and impulse of pressure phase) a three-dimensional mathematical model of gas mixture dynamics with chemical interaction is used. It allows controlling current pressure in every local point of actual space taking into account complex terrain. This information is used locally in every computational cell to evaluate the conditional probability of such consequences on human beings as ear-drum rupture and lethal ones on the basis of probit analysis. In order to use this technique automatically during the computational process the tabular dependence ""probit-functionimpact probability"" is replaced by a piecewise cubic spline. To evaluate the influence of the landscape profile on the non-stationary three-dimensional overpressure distribution above the earth surface near an epicenter of accidental hydrogen explosion a series of computational experiments with different variants of the terrain is carried out. Each variant differs in the level of mutual arrangement of the explosion epicenter and the places of possible location of personnel. Two control points with different distances from the explosion epicenter are considered. Diagrams of lethal and ear-drum rupture conditional probabilities are build to compare different variants of landscape profile. It is found that the increase or decrease in the level of the location of the control points relative to the level of the epicenter of the explosion significantly changes the scale of the consequences in the actual zone around the working places and should be taken into account by the risk managing experts at the stage of deciding on the level of safety at hydrogen fueling stations.

This paper deals with the main safety aspects of the EOS project. The partners of the project – Politecnico di Torino Gas Turbine Technologies (GTT Siemens group) Hysylab (Hydrogen System Laboratory) of Environment Park and Regione Piemonte – aim to create the main node of a regional fuel cell generator network. As a first step the Pennsylvania-based Stationary Fuel Cells division of Siemens Westinghouse Power Corporation (SWPC) supplied GTT with a CHP 100 kWe SOFC (Solide Oxide Fuel Cell) field unit fuelled by natural gas with internal reforming. The fuel cell is connected to the electricity national grid and provides part of the industrial district energy requirement. The thermal energy from the fuel cells is used for heating and air-conditioning of GTT offices bringing the total first Law efficiency of the plant to 70-80%. In the second phase of the EOS project (2007/2008) the maximum power produced by the SOFC systems installed in the GTT EOS test room will be increased to a total of about 225 kWe by means of an additional SOFC generator rated 125 kWe and up to 115 kWth. The paper provides information about the safety analysis which was performed during the main steps of the design of the system i.e. the HAZOP during the SOFC design by SWPC and the safety evaluations during the test hall design by GTT and Politecnico di Torino.

There is a great deal of knowledge and experience on the safe handling of hydrogen and the safe operation and management of hydrogen systems in South Africa. This knowledge and experience mostly sits within large gas supply companies and other large producers and consumers of hydrogen. However there appears to be less experience leading to a level of discomfort within regulatory bodies such as provincial and municipal fire departments and the national standards association. This compounded by a national policy of disallowing gas cylinders indoors has resulted in delays and indeed stalling in the process of obtaining permission to operate laboratories such as those of the national hydrogen programme HySA. In an effort to break this impasse two workshops were organised by HySA. The first was held at the CSIR’s facilities in Pretoria in October 2016. The second was held at the campus of the University of the Western Cape in Cape Town in May 2018. Four international experts and local experts in hydrogen regulations codes standards and safety addressed the 50-strong South African audiences via 5-way videoconferencing. This proved to be a very powerful tool to educate the audience and in particular the Tshwane (Pretoria) and Western Cape Fire Departments on the real issues risks and safety of hydrogen. The paper describes the South African Hydrogen RCS landscape the organisation and running of the workshops and the outputs achieved.

The H21 National Innovation Competition project is examining the feasibility of repurposing the existing GB natural gas distribution network for transporting 100% hydrogen. It aims to undertake an experimental testing programme that will provide the necessary data to quantify the comparative risk between a 100% hydrogen network and the natural gas network. The first phase of the project focuses on leakage testing of a strategic set of assets that have been removed from service which provide a representative sample of assets across the network. This paper presents the work undertaken for Phase 1A (background testing) where HSE and industry partners have tested a range of natural gas pipework assets of varying size material age and pressure-rating in a new bespoke open-air testing facility at the HSE Science and Research Centre Buxton. The assets have been pressurised with hydrogen and then methane and the leakage rate from the assets measured in both cases. The main finding of this work is that the assets tested which leak hydrogen also leak methane. None of the assets were found to leak hydrogen but not methane. In addition repair techniques that were effective at stopping methane leaks were also effective at stopping hydrogen leaks. The data from the experiments have been interpreted to obtain a range of leakage ratios between the two gases for releases under different conditions. This has been compared to the predicted ratio of hydrogen to methane volumetric leak rates for laminar (1.2:1) and turbulent (2.9:1) releases and good agreement was observed.

In order to ensure the safety of shore-based hydrogen bunkering operations this paper takes a 2000-ton bulk hydrogen powered ship as an example. Firstly the HAZID method is used to identify the hazards of hydrogen bunkering then the probability of each scenario is analyzed and then the consequences of scenarios with high risk based on FLACS software is simulated. Finally the personal risk of bunkering operation is evaluated and the bunkering restriction area is defined. The results show that the personal risk of shore-based bunkering operation of hydrogen powered ship is acceptable but the following risk control measures should be taken: (1) The bunkering restriction area shall be delineated and only the necessary operators are allowed to enter the area and control the any form of potential ignition source; (2) The hose is the high risk hazards during bunkering. The design form of bunkering arm and bunkering hose is considered to shorten the length of the hose as far as possible; (3) A safe distance between shore-based hydrogenation station and the building outside the station should be guaranteed. The results have a guiding role in effectively reducing the risk of hydrogen bunkering operation.

The Hydrogen Incidents and Accidents Database (HIAD) is an international open communication platform collecting systematic data on hydrogen-related undesired incidents which was initially developed in the frame of HySafe an EC co-funded Network of Excellence in the 6th Frame Work Programme by the Joint Research Centre of the European Commission (EC-JRC). It was updated by JRC as HIAD 2.01 in 2016 with the support of the Fuel Cells and Hydrogen 2 Joint Undertaking (FCH 2 JU). Since the launch of the European Hydrogen Safety Panel2 (EHSP) initiative in 2017 by FCH 2 JU the EHSP has worked closely with JRC to upload additional/new incidents to HIAD 2.0 and analyze them to gather statistics lessons learnt and recommendations through Task Force 3. The first report to summarise the findings of the analysis was published by FCH 2 JU in September 2019. Since the publication of the first report the EHSP and JRC have continuously worked together to enlarge HIAD 2.0 by adding newly occurred incidents as well as quality historic incidents which were not previously uploaded to HIAD 2.0. This has facilitated the number of validated incidents in HIAD 2.0 to increase from 272 in 2018 to 593 in March 2021. This number is also dynamic and continues to increase as new incidents are being continuously added by both EHSP and JRC; and validated by JRC. The overall quality of the published incidents has also been improved whenever possible. For example additional information has been added to some existing incidents. Since mid-2020 EHSP Task Force TF3 has further analysed the 485 events which were in the database as of July 2020. For completeness of the statistics these include the events considered in our first report3 as well as the newly added/validated events since then. In this process the EHSP has also re-visited the lessons learnt in the first report to harmonise the approaches of analysis and improve the overall analysis. The analysis has comprehensively covered statistics lessons learnt and recommendations. The increased number of incidents has also made it viable to extract statistics from the available incidents at the time of the analysis including previously available incidents. It should be noted that some incidents reported is of low quality therefore it was not included in the statistical analysis.

Regarding the problem of hydrogen diffusion of the fuel cell vehicle (HFCV) when its hydrogen supply system leaks this research uses the FLUENT software to simulate numerical values in the process of hydrogen leakage diffusion in both open space and closed space. This paper analyzed the distribution range and concentration distribution characteristics of hydrogen in these two different spaces. Besides this paper also took a survey about the effects of leakage rate wind speed wind direction in open space and the role the air vents play on hydrogen safety in closed space which provides a reference for the hydrogen safety of HFCV. In conclusion the experiment result showed that: In open space hydrogen leakage rate has a great influence on its diffusion. When the leakage rate doubles the hydrogen leakage range will expand about 1.5 times simultaneously. The hydrogen diffusion range is the smallest when the wind blows at 90 degrees which is more conducive to hydrogen diffusion. However when the wind direction is against the direction of the leakage of hydrogen the range of hydrogen distribution is maximal. Under this condition the risk of hydrogen leakage is highest. In an enclosed space when the vent is set closest to the leakage position the volume fraction of hydrogen at each time is smaller than that at other positions so it is more beneficial to safety.

This  paper  reports  on  the  results  of  interviews  conducted  with  21  representatives  from   emergency services organisations within Australia and New Zealand. With a relative emergent industry such as future fuels a chicken and egg situation does emerge with regards to how much training needs to be in place in advance of large-scale industry development or not. These respondents were employed in a variety of roles being directly involved in research and training of emerging technologies frontline operational  managers  and  other  senior  roles  across  the   emergency  services  sector.  Participants' responses to a series of questions were able to provide insights into the state of knowledge and training requirements within their organisations in relation to hydrogen and other future fuels. The findings suggest that formal and informal processes currently exist to support the knowledge development and transferal around the adoption of hydrogen and other future fuels. From the interviews it became clear that  there  are  a  number  of  processes  that  have  emerged  from  the  experiences  gained  through  the implementation   of  rooftop  solar  PV  and  battery  storage  that  provide  some  background  context  for advancing future fuels information across the sector. Because safety is a critical component for securing a social licence to operate engagement and knowledge sharing with any representatives from across this sector will only help to build confidence in the industry. Similarly because interviewees were very keen to access information they expressed a clear willingness to learn more through more formalised relationships rather than an ad hoc information seeking that has been employed to date. The presentation will  identify  key  recommendations  and  also  highlight  the   importance  of  QR  Codes in the emergency responder landscape. Implications for industry and policy makers are discussed.

The use of hydrogen storage tanks at 100% of nominal working pressure (NWP) is expected only after refuelling. Driving between refuellings is characterised by the state of charge SoC <100%. There is experimental evidence that Type IV tanks tested in a fire at initial pressures below 1/3 NWP leaked without rupture. This paper aims at understanding this phenomenon. The numerical research has demonstrated that the heat transfer from fire through the composite overwrap at storage pressures below NWP/3 is sufficient to melt the polymer liner. This melting initiates hydrogen microleaks through the composite before it loses the load-bearing ability. The fire-resistance rating (FRR) is defined as the time to rupture in a fire of a tank without or with blocked thermally activated pressure relief device. The dependence of a FRR on the SoC is demonstrated for the tanks with defined material properties and volumes in the range of 36–244 L. A composite wall thickness variation is shown to cause a safety issue by reducing the tank’s FRR and is suggested to be addressed by tank manufacturers and OEMs. The effect of a tank’s burst pressure ratio on the FRR is investigated. Thermal parameters of the composite wall i.e. decomposition heat and temperatures are shown in simulations of a tank failure in a fire to play an important role in its FRR.