Publications

Efficient storage of hydrogen is crucial for the success of hydrogen energy markets (early markets as well as transportation market). Hydrogen can be stored either as a compressed gas a refrigerated liquefied gas a cryo-compressed gas or in hydrides. This paper gives an overview of hydrogen storage technologies and details the specific issues and constraints related to the materials behaviour in hydrogen and conditions representative of hydrogen energy uses. It is indeed essential for the development of applications requiring long-term performance to have good understanding of long-term behaviour of the materials of the storage device and its components under operational loads.

The Australian Capital Territory (ACT) has legislated and aims to be net zero emissions by 2045. Such ambitious targets have implications for the contribution of hydrogen and its storage in gas distribution networks Therefore we need to understand now the impacts on the gas distribution network of the transition to 100% hydrogen. Assessment of the viability of decarbonising the ACT gas network will be partly based on the cost of reusing the gas network for the safe and reliable distribution of hydrogen. That task requires each element of the natural gas safety management system to be evaluated.

This article describes the construction of a test facility in Canberra Australia used to identify issues raised by 100% hydrogen use in the medium pressure distribution network consisting of nylon and polyethylene (PE) as a means of identifying measures necessary to ensure ongoing validity of the network's regulatory safety case.

Evoenergy (the ACT's gas distribution company) have constructed a Test Facility incorporating an electrolyser a gas supply pressure reduction and mixing skid a replica gas network and a domestic installation with gas appliances. Jointly with Australian National University (ANU) and Canberra Institute of Technology (CIT) the Company has commenced a program of “bench testing” initially with 100% hydrogen to identify gaps in the safety case specifically focusing on the materials work practices and safety systems in the ACT.

The facility is designed to assess:

•  Materials in use including aged network materials and components
•  Construction and installation techniques both greenfield and live gas work
•  Purging and filling techniques
•  Leak detection both underground and above ground
•  Emergency response and make safe techniques
•  Issues associated with use of hydrogen in light commercial and domestic appliances.

To educate and train:

•  Technicians and gas fitters on infrastructure installation and management
•  Emergency response services on responding to hydrogen related emergencies in a network environment; and
•  Manage public perceptions of hydrogen in a network environment.

Australia has an enviable safety record for the safe and reliable transport distribution and use of natural gas. The ACT natural gas network owned and operated by Evoenergy is one of the newest in Australia and has leveraged off the best materials and practices in Australia to build its network.

The paper addresses major safety issues relating to the production/storage distribution and consumer end use of hydrogen injected into existing gas distribution networks. The analysis is guided by the Safety Management System. The Hydrogen Testing Facility described in the paper provide tools for evaluation of hydrogen safety matters in the ACT and Australia-wide.

Testing to date has confirmed that polyethylene and nylon pipe and their respective jointing techniques can contain 100% hydrogen at pressures used for the distribution of natural gas. Testing has also confirmed that current installation work practices on polyethylene and nylon pipe and joints are suitable for hydrogen service. This finding is subject to variation attributable to staff training and skill levels and further testing has been programmed as outlined in this paper.

Testing of gas isolation by clamping and simulated repair on the hydrogen network has established that standard natural gas isolation techniques work with 100% hydrogen at natural gas pressures.

Explosion venting is a frequently used measure to mitigate the consequence of gas deflagrations in closed environments. Despite the effort to predict the vent area needed to achieved the protection through engineering formulas and CFD tools work has still to be done to reliably predict the outcome of a vented gas explosion. Blind-prediction exercises recently published show a large spread in the prediction of both engineering formula than CFD tools. University of Pisa performed experimental tests in a 25 m3 facility in inhomogeneous conditions and with the presence of simple obstacles constituted by plates bolted to HEB beams. The present paper is aimed to share the results of hydrogen dispersion and deflagration tests and discuss the comparison of maximum peak overpressure generated with different blockage ratio and repeated obstacles sets. Description of the experimental set-up includes all the details deemed necessary to reproduce the phenomenon with a CFD tool.

As the depletion of traditional fossil fuels and environmental pollution become a serious problem of human society researchers are actively finding renewable green energy sources. Considered as a clean efficient and renewable alternative Hydrogen energy is considered the most promising energy source. However the safe and efficient storage of hydrogen has become the major problem that hinders its application. To solve this gap this paper proposes to utilize surfactant modified graphene for hydrogen storage. With Hummers method and ultrasonic stripping method this study prepared graphene from graphene oxide with NaBH4. Surfactant sodium dodecylbenzene sulfonate (SDBS) was used as a dispersant during the reduction process to produce the dispersion-stabilized graphene suspensions. The characteristics of the graphene suspensions then were examined by XRD SEM TEM FT-IR Raman XPS TG and N2 adsorption-desorption tests. The hydrogen adsorption properties of the samples were investigated with Langmuir and Freundlich fitting. The results show that the adsorption behavior is consistent with the Freundlich adsorption model and the process is a physical adsorption.

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

This paper examines the flame dynamics of vented deflagration in stratified hydrogen layers. It also compares the measured combustion pressure transients with 3D GOTHIC simulations to assess GOTHIC’s capability in simulating the associated phenomena. The experiments were performed in the Large-Scale Vented Combustion Test Facility at the Canadian Nuclear Laboratories. The stratified layer was formed by injecting hydrogen at a high elevation at a constant flow rate. The dominant parameters for vented deflagrations in stratified layers were investigated. The experimental results show that significant overpressures are generated in stratified hydrogen–air mixtures with local high concentration although the volume-averaged hydrogen concentration is non-flammable. The GOTHIC predictions capture the overall pressure dynamics of combustion very well but the peak overpressures are consistently over-predicted particularly with higher maximum hydrogen concentrations. The measured combustion overpressures are also compared with Molkov’s model prediction based on a layer-averaged hydrogen concentration.

Emerging hydrogen energy technologies are creating new avenues for bring hydrogen fuel usage into larger public domain. Identification of possible accidental scenarios and measures to mitigate associated hazards should be well understood for establishing best practice guidelines. Accidentally released hydrogen forms flammable mixtures in a very short time. Ignition of such a mixture in congestion and confinements can lead to greater magnitudes of overpressure catastrophic for both structure and people around. Hence understanding of the permissible level of confinements and congestion around the hydrogen fuel handling and storage unit is essential for process safety. In the present study numerical simulations have been performed for the hydrogen-air turbulent deflagration in a well-defined congestion of repeated pipe rig experimentally studied by [1]. Large Eddy Simulations (LES) have been performed using the in-house modified version of the OpenFOAM code. The Flame Surface Wrinkling Model in the LES context is used for modelling deflagrations. Numerical predictions concerning the effects of hydrogen concentration and congestion on turbulent deflagration overpressure are compared with the measurements [1] to provide validation of the code. Further insight about the flame propagation and trends of the generated overpressures over the range of concentrations are discussed.

In this paper we analyze the potential factors affecting the hydrogen sulfide type of stress corrosion cracking in C110 casing pipes. In order to further study these cracking factors the methods of material property testing scanning electron microscopy XRD TEM and 3D ultra-depth-of-field were applied in the experiments. Besides that an HTHP autoclave was independently designed by the laboratory to simulate the actual corrosion environment and the potential factors affecting the stress corrosion cracking of C110 casing pipes were determined. The test results showed that the chemical composition metallographic structure hardness and non-metallic inclusions of the two types of C110 casing pipes were all qualified. In fact there remains a risk of stress corrosion cracking when the two kinds of C110 casing pipes serve under long-term field-working conditions. It is considered in this paper that the precipitates on the material surface stress damage and pitting corrosion are all critical factors affecting the stress corrosion cracking of casing pipes.

The United Kingdom has a vast scientific base across the entire Hydrogen and Fuel Cell research landscape with a world class academic community coupled with significant industrial activity from both UK-based Hydrogen and Fuel Cell companies and global companies with a strong presence within the country. The Hydrogen and Fuel Cell (H2FC) SUPERGEN Hub funded by the Engineering and Physical Sciences Research Council (EPSRC) was established in 2012 as a five-year programme to bring the UK's H2FC research community together. Here we present the UK's current Hydrogen and Fuel Cell activities along with the role of the H2FC SUPERGEN Hub.

This paper describes validation of the computational fluid dynamics tool FLACS-Hydrogen. The validation study focuses on concentration and pressure data from vented deflagration experiments performed in 20-foot shipping containers as part of the project Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations (HySEA) funded by the Fuel Cells and Hydrogen 2 Joint Undertaking (FCH 2 JU). The paper presents results for tests involving inhomogeneous hydrogen-air clouds generated from realistic releases performed during the HySEA project. For both experiments and simulations the peak overpressures obtained for the stratified mixtures are higher than those measured for lean homogeneous mixtures with the same amount of hydrogen. Using an in-house version of FLACS-Hydrogen with the numerical solver Flacs3 and improved physics models results in significantly improved predictions of the peak overpressures compared to the predictions by the standard Flacs2 solver. The paper includes suggestions for further improvements to the model system.

Recent advances in optical sensors show promise for the development of new wide area monitoring and distributed optical network hydrogen detection systems. Optical hydrogen sensing technologies reviewed here are: 1) open path Raman scattering systems 2) back scattering from chemically treated solid polymer matrix optical fiber sensor cladding; and 3) schlieren and shearing interferometry imaging. Ultrasonic sensors for hydrogen release detection are also reviewed. The development status of these technologies and their demonstrated results in sensor path length low hydrogen concentration detection ability and response times are described and compared to the corresponding status of hydrogen spot sensor network technologies.

Short refuelling time and high final state of charge are among the main hydrogen car user's requirements. To meet these requirements without exceeding the tank materials safety limits hydrogen precooling is needed. Filling experiments with different inlet gas temperatures and mass flow rates have been executed using two different types of on-board tanks (type 3 and 4). State of charge has a strong dependency on the inlet gas temperature. This dependency is more visible for type 4 tanks. Lowest precooling temperature (−40 °C) is not always required in order to meet user's requirements so energy savings can be achieved if the initial conditions of the tank are correctly identified. The results of the experiments performed have been compared with the SAE J2601 look-up tables for non-communication fillings. A big safety margin has been observed in these tables. Refuelling could be performed faster and with less demanding precooling requirements if the initial conditions and the configuration of the hydrogen storage system are well known.

Determining the risk of accidental ignition of flammable mixtures is a topic of tremendous importance in industry and aviation safety. The concept of minimum ignition energy (MIE) has traditionally formed the basis for studying ignition hazards of fuels. In recent years however the viewpoint of ignition as a statistical phenomenon has formed the basis for studying ignition as this approach appears to be more consistent with the inherent variability in engineering test data. We have developed a very low energy capacitive spark ignition system to produce short sparks with fixed lengths of 1 to 2 mm. The ignition system is used to perform spark ignition tests in lean hydrogen oxygen-argon test mixtures over a range of spark energies. The test results are analyzed using statistical tools to obtain probability distributions for ignition versus spark energy demonstrating the statistical nature of ignition. The results also show that small changes in the hydrogen concentration lead to large changes in the ignition energy and dramatically different flame characteristics. A second low-energy spark ignition system is also developed to generate longer sparks with varying lengths up to 10 mm. A second set of ignition tests is performed in one of the test mixtures using a large range of park energies and lengths. The results are analyzed to obtain a probability distribution for ignition versus the spark energy per unit spark length. Preliminary results show that a single threshold MIE value does not exist and that the energy per unit length may be a more appropriate parameter for quantifying the risk of ignition.

Protective walls are a well-known and efficient way to mitigate overpressure effects of accidental explosions (detonation or deflagration). For detonation there are multiple published studies whereas for deflagration no well-adapted and rigorous method has been reported in the literature. This article describes the validation of a new modelling approach for fast deflagrations of H2. This approach includes two steps. At the first step the combustion phase of vapor cloud explosion (VCE) involving a fast deflagration is substituted by equivalent vessel burst problem. The purpose of this step is to avoid the reactive flow computations. At the second step CFD is used for computations of pressure propagation from the equivalent (non reactive) vessel burst problem. After verifying the equivalence of the fast deflagration and the vessel burst problem at the first step the capability of two CFD codes such as FLACS and Europlexus are examined for modelling of the vessel burst problem (with and without barriers). Finally the efficiency of finite and infinite barriers used for mitigation of the shock is investigated

The effect of surfaces on the extent of high pressure horizontal unignited jets of hydrogen and methane is studied using CFD numerical simulations performed with FLACS Hydrogen. Results for constant flow rate through a 6.35 mm PRD from 100 barg and 700 barg storage units are presented for horizontal hydrogen and methane jets. To quantify the effect of a horizontal surface on the jet the jet exit is positioned at various heights above the ground ranging from 0.1 m to 10 m. Free jet simulations are performed for comparison purposes.

The International Energy Agency's Hydrogen Implementing Agreement (IEA HIA) was established in 1977 to pursue collaborative hydrogen research and development and information exchange among its member countries. Information and knowledge dissemination is a key aspect of the work within IEA HIA tasks and case studies technical reports and presentations/publications often result from the collaborative efforts. The work conducted in hydrogen safety under Task 31 and its predecessor Task 19 can positively impact the objectives of national programs even in cases for which a specific task report is not published. The interactions within Task 31 illustrate how technology information and knowledge exchange among participating hydrogen safety experts serve the objectives intended by the IEA HIA.

In many processes where hydrogen may be released from below a liquid surface there has been concern regarding how such releases might ultimately disperse in an ullage space. Knowledge of the extent and persistence of any flammable volume formed is needed for hazardous area classification as well as for validation of explosion modelling or experiments. Following an initial release of hydrogen the overall process can be subdivided into three stages (i) rise and possible break-up of a bubble in the liquid (ii) formation and bursting of a thin gas-liquid-gas interface at the liquid surface and (iii) dispersion of the released gas. An apparatus based on a large glass sided water tank has been constructed which employs two synchronised high-speed imaging systems to record the behaviour of hydrogen bubble release and dispersion. A high-speed digital video system records the rising of the bubbles and the formation and bursting of the gas-liquid-gas interface at the liquid surface. An additional schlieren system is used to visualise the hydrogen release as bubbles burst at the liquid surface. The bubble burst mechanism can clearly be described from the results obtained. Following the nucleation of a hole surface tension causes the liquid film to peel back rapidly forming a ring/torus of liquid around the enlarging hole. This process lasts only a few milliseconds. Although some hydrogen can be seen to be expelled from the bubble much seems to remain in place as the film peels away. To assess the extent of the flammable plume following a bubble burst the apparatus was modified to include an electric-arc igniter. In order to identify plumes coincident in space with the igniter a schlieren system was built capable of recording simultaneously in two orthogonal directions. This confirmed that clouds undetected by the schlerien imaging could not be ignited with the electric arc igniter.

High gas temperatures can be reached inside a hydrogen tank during the filling process because of the large pressure increase (up to 70-80 MPa) and because of the short time (~3 minutes) of the process. High temperatures can potentially jeopardize the structural integrity of the storage system and one of the strategies to reduce the temperature increase is to pre-cool the hydrogen before injecting it into the tank. Computational Fluid Dynamics (CFD) tools have the capabilities of capturing the flow field and the temperature rise in the tank. The results of CFD simulations of fast filling with pre-cooling are shown and compared with experimental data to assess the accuracy of the CFD model

Decarbonization of the shipping sector is inevitable and can be made by transitioning into low‐ or zero‐carbon marine fuels. This paper reviews 22 potential pathways including conventional Heavy Fuel Oil (HFO) marine fuel as a reference case “blue” alternative fuel produced from natural gas and “green” fuels produced from biomass and solar energy. Carbon capture technology (CCS) is installed for fossil fuels (HFO and liquefied natural gas (LNG)). The pathways are compared in terms of quantifiable parameters including (i) fuel mass (ii) fuel volume (iii) life cycle (Well‐To‐ Wake—WTW) energy intensity (iv) WTW cost (v) WTW greenhouse gas (GHG) emission and (vi) non‐GHG emissions estimated from the literature and ASPEN HYSYS modelling. From an energy perspective renewable electricity with battery technology is the most efficient route albeit still impractical for long‐distance shipping due to the low energy density of today’s batteries. The next best is fossil fuels with CCS (assuming 90% removal efficiency) which also happens to be the lowest cost solution although the long‐term storage and utilization of CO2 are still unresolved. Biofuels offer a good compromise in terms of cost availability and technology readiness level (TRL); however the non‐GHG emissions are not eliminated. Hydrogen and ammonia are among the worst in terms of overall energy and cost needed and may also need NOx clean‐up measures. Methanol from LNG needs CCS for decarbonization while methanol from biomass does not and also seems to be a good candidate in terms of energy financial cost and TRL. The present analysis consistently compares the various options and is useful for stakeholders involved in shipping decarbonization.

This study deals with the TNO Multi-Energy and Baker-Strehlow-Tang (BST) methods for estimating the positive overpressures and positive impulses resulting from hydrogen-air explosions. With these two methods positive overpressure and positive impulse results depend greatly on the choice of the class number for the TNO Multi-Energy method or the Mach number for the BST methods. These two factors permit the user to read the reduced parameters of the blast wave from the appropriate monographs for each of these methods i.e. positive overpressure and positive duration phase for the TNO Multi-Energy method and positive overpressure and positive impulse for the BST methods. However for the TNO Multi-Energy method the determination of the class number is not objective because it is the user who makes the final decision in choosing the class number whereas with the BST methods the user is strongly guided in their choice of an appropriate Mach number. These differences in the choice of these factors can lead to very different results in terms of positive overpressure and positive impulse. Therefore the objective of this work was to compare the positive overpressures and positive impulses predicted with the TNO Multi-Energy and BST methods with data available from large-scale experiments.

This work presents a parametric study on the similitude between hydrogen and helium distribution when released in the air by a source located inside of a naturally ventilated enclosure with two vents. Several configurations were experimentally addressed in order to improve knowledge on dispersion. Parameters were chosen to mimic operating conditions of hydrogen energy systems. Thus the varying parameters of the study were mainly the source diameter the releasing flow rate the volume and the geometry of the enclosure. Two different experimental set-ups were used in order to vary the enclosure's height between 1 and 2 m. Experimental results obtained with helium and hydrogen were compared at equivalent flow rates determined with existing similitude laws. It appears for the plume release case that helium can suitably be used for predicting hydrogen dispersion in these operating designs. On the other hand – when the flow turns into a jet – non negligible differences between hydrogen and helium dispersion appear. In this case helium – used as a direct substitute to hydrogen – will over predict concentrations we would get with hydrogen. Therefore helium concentration read-outs should be converted to obtain correct predictions for hydrogen. However such a converting law is not available yet.

Hydrogen is being considered as a pathway to decarbonize large energy systems and for utility-scale energy storage. As these applications grow transportation infrastructure that can accommodate large quantities of hydrogen will be needed. Many millions of tons of hydrogen are already consumed annually some of which is transported in dedicated hydrogen pipelines. The materials and operation of these hydrogen pipeline systems however are managed with more constraints than a conventional natural gas pipeline. Transitional strategies for deep decarbonization of energy systems include blending hydrogen into existing natural gas systems where the materials and operations may not have the same controls. This study explores the hydrogen compatibility of existing pipeline steels and the suitability of these steels in hydrogen pipeline systems. Representative fracture and fatigue properties of pipeline grade steels in gaseous hydrogen are summarized from the literature. These properties are then considered in idealized design life calculations to inform materials performance for a typical gas pipeline.

The addition of hydrogen to natural gas for heating and cooking is being considered as a route to reducing carbon emissions in the United Kingdom (UK). The HyDeploy programme (hereafter referred to as HyDeploy) aims to demonstrate that hydrogen can be added to the natural gas supply without compromising public safety or appliance performance. This paper relates to the preparatory work for hydrogen injection on a live site at Keele University closed network comprising domestic premises multi-occupancy buildings and light commercial premises. The project is based around the injection of up to 20 %mol/mol hydrogen into mains natural gas at pressures below 2 barg. Work streams addressed during the pre-trial preparation included; assessment of material interaction with hydrogen blends for all distribution system components and appliances; understanding of gas appliance behaviour; review of: gas detection systems fire and explosion considerations routine and emergency procedural considerations; and the design of a new hydrogen injection grid entry unit. This paper describes the safety and regulatory challenges that were encountered during preparation of the project including obtaining the necessary regulatory permissions to blend hydrogen gas.

Experimental data from vented explosion tests using lean hydrogen–air mixtures with concentrations from 12 to 19% vol. are presented. A 63.7-m3 chamber was used for the tests with a vent size of either 2.7 or 5.4 m2. The tests were focused on the effect of hydrogen concentration ignition location vent size and obstacles on the pressure development of a propagating flame in a vented enclosure. The dependence of the maximum pressure generated on the experimental parameters was analyzed. It was confirmed that the pressure maxima are caused by pressure transients controlled by the interplay of the maximum flame area the burning velocity and the overpressure generated outside of the chamber by an external explosion. A model proposed earlier to estimate the maximum pressure for each of the main pressure transients was evaluated for the various hydrogen concentrations. The effect of the Lewis number on the vented explosion overpressure is discussed.

A key element in the safe operation of a modern gas distribution system is gas detection. The addition of hydrogen to natural gas will alter the characteristics of the fuel and therefore its impact on gas detection must be considered. It is important that gas detectors remain sufficiently sensitive to the presence of hydrogen and natural gas mixtures and that they do not lead to false readings. This paper presents analyses of work performed as part of the Office for Gas and Energy Markets (OFGEM) funded HyDeploy project on the response of various natural gas industry detectors to blended mixtures up to 20 volume percent (vol%) of hydrogen in natural gas. The scope of the detectors under test included survey instruments and personal monitors that are used in the gas industry. Four blend ratios were analysed (0 10 15 and 20 vol% hydrogen in natural gas). The laboratory testing undertaken investigated the following:

• Flammable response to blends in the ppm range (0-0.2 vol%);
• Flammable response to blends in the lower explosion limit range (0.2-5 vol%);
• Flammable response to blends in the volume percent range (5-100 vol%);
• Oxygen response to blends in the volume percent range (0-25 vol%); and
• Carbon monoxide response to blends in the ppm range (0-1000 ppm).

Catalytic and thermal conductivity based flammable detectors in the volume percent range are as expected affected in the form of a relative increase in output. All of the carbon monoxide detectors tested were found to be cross-sensitive to hydrogen in the blended mixtures tested at levels which have the potential to cause false alarms at current permissible leakage rates. In summary a number of measurement ranges across multiple detectors commonly used in the gas industry have been found to be cross-sensitive to hydrogen in natural gas blends to differing degrees. This required the HyDeploy project to select alternative instruments for the purpose of gas detection as part of the trial. This paper relates to the preparatory work to introduce hydrogen into the Keele closed network.

Within the scope of the French national project DRIVE and European project HyPER high pressure jet flames of hydrogen were produced and instrumented.<br/>The experimental technique and measurement strategy are presented. Many aspects are original developments like the direct measurement of the mass flow rate by weighing continuously the hydrogen container the image processing to extract the flame geometry the heat flux measurement device the thermocouples arrangement…<br/>Flames were observed from 900 bar down to 1 bar with orifices ranging from 1 to 3 mm. An original set of data is now available about the main flame characteristics and about some thermodynamic aspects of hydrogen releases under high pressure.<br/>A brief comparison of some available models is presented.

Production of iron and steel releases seven percent of the global greenhouse gas (GHG) emissions. Incremental changes in present primary steel production technologies would not be sufficient to meet the emission reduction targets. Replacing coke used in the blast furnaces as a reducing agent with hydrogen produced from water electrolysis has the potential to reduce emissions from iron and steel production substantially. Mass and energy flow model based on an open-source software (Python) has been developed in this work to explore the feasibility of using hydrogen direct reduction of iron ore (HDRI) coupled with electric arc furnace (EAF) for carbon-free steel production. Modeling results show that HDRI-EAF technology could reduce specific emissions from steel production in the EU by more than 35% at present grid emission levels (295 kgCO2/MWh). The energy consumption for 1 ton of liquid steel (tls) production through the HDRI-EAF route was found to be 3.72 MWh which is slightly more than the 3.48 MWh required for steel production through the blast furnace (BF) basic oxygen furnace route (BOF). Pellet making and steel finishing processes have not been considered. Sensitivity analysis revealed that electrolyzer efficiency is the most important factor affecting the system energy consumption while the grid emission factor is strongly correlated with the overall system emissions.

The report summarizes experimental results on the mechanisms and kinetics of hydrogen-air flammable gas cloud formation and evolution due to foreseeable (less than 10-3 kg/sec) hydrogen leaks into confined spaces with different shapes sizes and boundary conditions. The goals were - 1) to obtain qualitative information on the basic gas-dynamic patterns of flammable cloud formation at different leak velocities (between 935 and 905 m/sec) for a fixed leak flowrate and 2) to collect quantitative data on spatial and temporal characteristics of the revealed patterns. Data acquisition was performed using a spatially distributed reconfigurable net of 24 hydrogen gauges with short response time. This experimental innovation permits to study spatial features of flammable cloud evolution in detail which previously was attainable only from CFD computations. Two qualitatively different gas dynamic patterns were documented for the same leak flowrate. In one limiting case (sufficiently low speed of leak) the overall gas-dynamic pattern can be described by the well-known “filling box” model. In another limited case (high velocity of leak) it is proposed to describe the peculiarities of gas-dynamic behavior of flammable cloud by the term of a “fading up box” model. From the safety view point the “fading up box” case is more hazardous than the “filling box” case. Differences in macroscopic and kinetic behavior which are essential for safety provision are presented. Empirical non-dimensional criterion for discrimination of the two revealed basic patterns for hydrogen leaks into confined spaces with comparable length scale is proposed. The importance of the revealed “fading up box” gas-dynamic pattern is discussed for development of an advanced hydrogen gauges system design and safety criteria.

A new route for making steel from iron ore based on the use of hydrogen to reduce iron oxides is presented detailed and analyzed. The main advantage of this steelmaking route is the dramatic reduction (90% off) in CO2 emissions compared to those of the current standard blast-furnace route. The first process of the route is the production of hydrogen by water electrolysis using CO2-lean electricity. The challenge is to achieve massive production of H2 in acceptable economic conditions. The second process is the direct reduction of iron ore in a shaft furnace operated with hydrogen only. The third process is the melting of the carbon-free direct reduced iron in an electric arc furnace to produce steel. From mathematical modeling of the direct reduction furnace we show that complete metallization can be achieved in a reactor smaller than the current shaft furnaces that use syngas made from natural gas. The reduction processes at the scale of the ore pellets are described and modeled using a specific structural kinetic pellet model. Finally the differences between the reduction by hydrogen and by carbon monoxide are discussed from the grain scale to the reactor scale. Regarding the kinetics reduction with hydrogen is definitely faster. Several research and development and innovation projects have very recently been launched that should confirm the viability and performance of this breakthrough and environmentally friendly ironmaking process.

We present an experimental study on the dispersion of helium in an enclosure of 1 m3 with natural ventilation through one vent. Three vent geometries have been studied. Injection parameters have been varied so that the injection Richardson number ranges from 2·10−6 to 9 and the volume Richardson number which gives the ability of the release to mix the enclosure content ranges from 8·10−4 to 900. It has been found that the vertical distribution of helium volume fraction can exhibit significant gradient. Nevertheless the results are compared to the simple analytical model based on the homogenous mixture hypothesis which gives fairly good estimates of the maximum helium volume fraction.

Results are given of experimental study of propagation of explosion waves in hydrogen-air mixtures of different compositions under conditions of cumulation. The investigations are performed in a setup consisting of two parts namely the upper part in the form of a metal cone and the lower part in the form of a rubber envelope hermetically attached to the cone. The upper and lower parts of the experimental setup are separated by a thin rubber film and may be filled with hydrogen-air mixtures of different compositions.

The use of hydrogen as an energy carrier is a real perspective for Europe since a number of breakthroughs now enable to envision a deployment at the industrial scale. However some safety issues need to be further addressed but experimental data are still lacking especially about the explosion dynamics in realistic dimensions. A set of hydrogen-air vented explosions were thus performed in two medium scale chambers (1 m3 and 10 m3). Homogeneous mixtures were used (10% to 30% vol.). The explosion overpressure was measured inside the chamber and outside on the axis of the discharge from the vent. The incidence of the external explosion is clearly seen. All the results in this paper and the predictions from the standards differ greatly meaning that a significant effort is still required. It is the purpose of the French project DIMITRHY to help progressing.

Generalised continuum model of hydrogen transport to fracture loci is developed for the purposes of analysis of the hydrogenous environment assisted fracture (HEAF). The model combines the notions of the theories of gas flow surface science and diffusion and trapping in stressed solids. Derived flux and balance equations describe the species migration across different states (gas adsorbed specie at the gas-metal interface interstitial solute in metal bulk) and a variety of corresponding sites of energy minimums along the potential relief for hydrogen in a system. The model accounts for the local kinetics of hydrogen interchange between the closest dissimilar neighbour sites and for the nonlocal interaction of hydrogen trapping in definite positions with the species wandering in their farer surroundings. In particular situations certain balance equations of the model may degenerate into equilibrium constraints as well as some terms in the generalised equations may be insignificant. A series of known theories of hydrogen transport in material-environment system can be recovered then as particular limit cases of the generalised model. Presented theory can help clarifying the advantages and limitations of particularised models so that appropriate one may be chosen for the analysis of a particular HEAF case.

Hydrogen technologies such as hydrogen fuelled vehicles and refuelling stations are being tested in practice in a number of projects (e.g. HyFleet-Cute and Whistler project) giving valuable information on the reliability and maintenance requirements. In order to establish refuelling stations the permitting authorities request qualitative and quantitative risk assessments to show the safety and acceptability in terms of failure frequencies and respective consequences. For new technologies not all statistical data can be established or are available in good quality causing assumptions and extrapolations to be made. Therefore the risk assessment results contain varying degrees of uncertainty as some components are well established while others are not. The paper describes a methodology to evaluate the degree of uncertainty in data for hydrogen applications based on the bias concept of the total probability and the NUSAP concept to quantify uncertainties of new not fully qualified hydrogen technologies and implications to risk management.

There are currently projects and demonstration programs aiming at introducing Hydrogen powered Fuel Cell (HFC) vehicles into the market. Regione Toscana has been cofounder of the project “H2 Filiera Idrogeno” whose goal is to achieve a clean and sustainable mobility through HFC vehicle studies covering their production storage and use. Among the goals of the project was the substitution of the electric propulsion system with a hydrogen fuel cells propulsion system. This work presents a brief overview of the necessary modifications of the electric propulsion version of a Piaggio Porter to host a H2 fuel cell and experimental studies of realistic H2 releases from the vehicle. The scenarios covered H2 unintended releases underneath the vehicle when at rest and focused on three types of releases diffusive major and minor that might reach the interior of the vehicle and potentially pose a direct risk to the passengers.

Numerical simulations have been carried out for pressurised hydrogen release through a nozzle in a simulated vehicle refilling environment of an experiment carried out in a joint industry project by Shell bp Exxon and the UK HSE Shirvill[1]. The computational domain mimics the experimental set up for a vertical downwards release in a vehicle refuelling environment. Due to lack of detailed data on pressure decay in the storage cylinder following the release a simple analytical model has also been developed to provide the transient pressure conditions at nozzle exit. The modelling is carried out using the traditional Computational fluid dynamics (CFD) approach based on Reynolds averaged Navier Stokes equations. The Pseudo diameter approach is used to bypass the shock-laden flow structure in the immediate vicinity of the nozzle. For combustion the Turbulent Flame Closure (TFC) model is used while the shear stress transport (SST) model is used for turbulence

The fourth Strategic Energy Plan adopted in April 2014 stated ""a road map toward realization of a “hydrogen society” will be formulated and a council which comprises representatives of industry academia and government and which is responsible for its implementation will steadily implement necessary measures while progress is checked". Then the Council for a Strategy for Hydrogen and Fuel Cells which was held in June in the same year as a conference of experts from industry academia and government compiled a Strategic Roadmap for Hydrogen and Fuel Cells (hereinafter referred to as ""the Roadmap"") presenting efforts to be undertaken by concerned parties from the public/private sector aimed at building a hydrogen-based society.<br/>The Roadmap was revised in March 2016 in response to the progress of the efforts to include the schedule and quantitative targets to make the fuel cells for household use (Ene-Farm) fuel cell vehicles (FCVs) and hydrogen stations self-reliant. In April 2017 the first Ministerial Council on Renewable Energy Hydrogen and Related Issues was held. The Council decided to establish--by the end of the year--a basic strategy that would allow the government to press on with the measures in an integrated manner to realize a hydrogen-based society for the first time in the world. The second Ministerial Council on Renewable Energy Hydrogen and Related Issues was then held in December of that year to establish the Basic Hydrogen Strategy. The Strategy was positioned as a policy through which the whole government would promote relevant measures and proposed that hydrogen be another new carbon-free energy option. By setting a target to be achieved by around 2030 the Strategy provides the general direction and vision that the public and private sectors should share with an eye on 2050.<br/>Furthermore the fifth Strategic Energy Plan was adopted in July 2018. In order for hydrogen to be available as another new energy option in addition to renewable energy the Plan showed the correct direction of hydrogen energy in the energy policy specifically reducing the hydrogen procurement/supply cost to a level favorably comparable with that of existing energies while taking the calculated environmental value into account.

An increase in the number of hydrogen-fuelled applications in the marketplace will require a better understanding of the potential for fires and explosion associated with the unintended release of hydrogen within a structure. Predicting the temporally evolving hydrogen concentration in a structure with unknown release rates leak sizes and leak locations is a challenging task. A simple analytical model was developed to predict the natural and forced mixing and dispersion of a buoyant gas released in a partially enclosed compartment with vents at multiple levels. The model is based on determining the instantaneous compartment over-pressure that drives the flow through the vents and assumes that the helium released under the automobile mixes fully with the surrounding air. Model predictions were compared with data from a series of experiments conducted to measure the volume fraction of a buoyant gas (at 8 different locations) released under an automobile placed in the center of a full-scale garage (6.8 m × 5.4 m × 2.4 m). Helium was used as a surrogate gas for safety concerns. The rate of helium released under an automobile was scaled to represent 5 kg of hydrogen released over 4 h. CFD simulations were also performed to confirm the observed physical phenomena. Analytical model predictions for helium volume fraction compared favourably with measured experimental data for natural and forced ventilation. Parametric studies are presented to understand the effect of release rates vent size and location on the predicted volume fraction in the garage. Results demonstrate the applicability of the model to effectively and rapidly reduce the flammable concentration of hydrogen in a compartment through forced ventilation.

In this paper the detonation propensity of different compositions of mixtures of hydrogen propane and methane with air has been evaluated over a wide range of compositions. We supplement the conventional calculations of the induction delay with calculations of the characteristic acceleration parameter recently suggested by Radulescu Sharpeand Bradley(RSB) to characterize the instability of detonations. While it is well established that the ignition delay provides a good measure for detonability the RSB acceleration or its non-dimensionalform provides a further discriminant between mixtures with similar ignition delays. The present assessment of detonability reveals that while a stoichiometric mixture of hydrogen-air has an ignition delay one and two orders of magnitude shorter than respectively propane and methane hydrogen also has a parameter smaller by respectively one and two orders of magnitude. Its smaller propensity for instability is reflected by an RSB acceleration parameter similar to the two hydrocarbons. The predictions however indicate that lean hydrogen mixtures are likely to be much more unstable than stoichiometric ones. The relation between the parameter and potential to amplify an unstable transverse wave structure has been further determined through numerical simulation of decaying reactive Taylor-Sedov blast waves. Using a simplified two-step model calibrated for these fuels we show that methane mixtures develop cellular structures more readily than propane and hydrogen when observed on similar induction time scales. Future work should be devoted towards a quantitative inclusion of the RSB parameter in assessing the detonability of a given mixture.

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.

The paper describes CFD modelling of lean hydrogen mixture deflagrations. Large eddy simulation (LES) premixed combustion model developed at the University of Ulster to account phenomena related to large-scale deflagrations was adjusted specifically for lean hydrogen-air flames. Experiments by Kumar (2006) on lean hydrogen-air mixture deflagrations in a 120 m3  vessel at initially quiescent conditions were simulated. 10% by volume hydrogen-air mixture was chosen for simulation to provide stable downward flame propagation; experiments with the smallest vent area 0.55 m2  were used as having the least apparent flame instabilities affecting the pressure dynamics. Deflagrations with igniter located centrally near vent and at far from the vent wall were simulated. Analysis of simulation results and experimental pressure dynamics demonstrated that flame instabilities developing after vent opening made the significant contribution to maximum overpressure in the considered experiments. Potential causes of flame instabilities are discussed and their comparative role for different igniter locations is demonstrated.

The European Strategy Forum on Research Infrastructures (ESFRI) recognizes in its roadmap for Research Infrastructures that ?in the near future hydrogen as an energy carrier derived from various other fuels and fuel cells as energy transformers are expected to come into a major role for mobility but also for different other mobile and stationary applications? |1|. This modern hydrogen driven society lags far behind the reality. Because of that it is conform to question the current situation concerning the belief that already most is comprehensively investigated and developed concerning hydrogen technology is correct and already done. From that it appears the hydrogen technology is market ready only partial and not prepared in a sufficient way to get finally included and adopted in modern hydrogen driven society and especially the acceptance of the society is a critical. Beside this critical view through society several scientific and technical bottlenecks still discoverable. Nevertheless it is possible to foster furthermore science and development on hydrogen technology. The ?Integrating European Infrastructure? was created to support science and development of hydrogen and fuel cell technologies towards European strategy for sustainable competitive and secure energy also while identifying scientific and technical bottlenecks to support solutions based on. Its acronym is H2FC European Infrastructure and was formed to integrate the European R&D community around rare and/or unique infrastructural elements that will facilitate and significantly enhance the research and development of hydrogen and fuel cell technology.

Hydrogen is widely recognised as an important option for future road transportation but a widespread infrastructure must be developed if the potential for hydrogen is to be achieved. This paper and related appendices which can be downloaded as Supplementary material present a mixed-integer linear programming model (called SHIPMod) that optimises a hydrogen supply chains for scenarios of hydrogen fuel demand in the UK including the spatial arrangement of carbon capture and storage infrastructure. In addition to presenting a number of improvements on past practice in the literature the paper focuses attention on the importance of assumptions regarding hydrogen demand. The paper draws on socio-economic data to develop a spatially detailed scenario of possible hydrogen demand. The paper then shows that assumptions about the level and spatial dispersion of hydrogen demand have a significant impact on costs and on the choice of hydrogen production technologies and distribution mechanisms.

A numerical approach is developed to simulate detonation propagation attenuation failure and re-initiation in hydrogen–air mixture. The aim is to study the condition under which detonations may fail or re-initiate in bifurcated tubes which is important for risk assessment in industrial accidents. A code is developed to solve compressible multidimensional transient reactive Navier–Stokes equations. An Implicit Large Eddy Simulation approach is used to model the turbulence. The code is developed and tested to ensure both deflagrations (when detonation fails) and detonations are simulated correctly. The code can correctly predict the flame properties as well as detonation dynamic parameters. The detonation propagation predictions in bifurcated tubes are validated against the experimental work of Wang et al. [12] and found to be in good agreement with experimental observations.

The detonation propensity of hydrogen-air mixtures with addition of methane ethane or propane in wide range of compositions is analyzed. The analysis concerned the detonation cell width ignition delay time RSB and parameters. Results are presented as a function of hydrogen molar fraction. Computations were performed with the use of three Cantera 2.1.1. scripts in the Matlab R2010b environment. The validated mechanisms of chemical reactions based on data available in the literature were used. Six mechanisms were assessed: GRI-Mech 3.0 LLNL SanDiego Wang POLIMI and AramcoMech. In conclusion the relation between detonation propensity parameters is discussed.

Any technical installation need appropriate safety barriers installed to prevent or mitigate any adverse effects concerning people property and environment. In this context a safety barrier is a series of elements each consisting of a technical system or human action that implement a planned barrier function to prevent control or mitigate the propagation of a condition or event into an undesired condition or event. This is also important for new technologies as hydrogen refuelling stations being operated at very high pressures up to 900bar. In order to establish the needed barriers a hazard identification of the installation has to be carried out to identify the possible hazardous events. In this study this identification was done using the generic layout of a future large hydrogen refuelling station that has been developed by the EU NoE HySafe. This was based on experiences with smaller scale refuelling stations that has been in operation for several years e.g. being used in the former CUTE and ECTOS projects. Using this approach the object of the study is to support activities to further improve the safety performance of future larger refuelling stations. This will again help to inform the authorities and the public to achieve a proper public awareness and to support building up a realistic risk and safety perception of the safety on such future refuelling stations. In the second step the hazardous events that may take place and the barriers installed to stop hazards and their escalation are analysed also using in-house developed software to model the barriers and to quantify their performance. The paper will present an overview and discuss the state-of-the-art of the barriers established in the generic refuelling station.

The paper presents HyResponse project i.e. a European Hydrogen Safety Training Platform that targets to train First responders to acquire professional knowledge and skills to contribute to FCH permitting process as approving authority. The threefold training program is described: educational training operational-level training on mock-up real scale transport and hydrogen stationary installations and innovative virtual training exercises reproducing entire accident scenarios. The paper highlights how the three pilot sessions for European First Responders in a face to face mode will be organized to get a feedback on the training program. The expected outputs are also presented i.e. the Emergency Response Guide and a public website including teaching material and online interactive virtual training.

In this study a solution for a liquid pool spreading model with a continuous spill is compared with that for a liquid pool spreading model with an instantaneous spill under the same total release volume. As reducing spill time in completely releasing liquid from a tank it is evaluated whether the solution for a continuous spill approaches to that for an instantaneous spill or not. Also effects of the viscous term in the liquid pool spreading model with continuous and instantaneous spills on the liquid pool spreading behaviour are investigated.

In 2016 for the first time a polymer electrolyte fuel cell free of Pt electrocatalysts was shown to deliver more than 0.5 W cm-2 of peak power density from H2 and air (CO2 free). This was achieved with a silver-based oxygen reduction (ORR) cathode and a Pd-CeO2 hydrogen oxidation reaction (HOR) anodic electrocatalyst. The poor kinetics of the HOR under alkaline conditions is a considerable challenge to Anion Exchange Membrane Fuel Cell (AEMFC) development as high Pt loadings are still required to achieve reasonable performance. Previously the ameliorative combination of Pd and CeO2 nanocomposites has been exploited mostly in heterogeneous catalysis where the positive interaction is well documented. Carbon supported PdCeO2 HOR catalysts have now been prepared by different synthetic techniques and employed in AEMFCs as alternative to Pt and PtRu standards. Important research has also been recently reported delving into the origin of the HOR enhancement on Pd-CeO2. Such work has highlighted the importance of the bifunctional mechanism of the HOR at high pHs. Carefully prepared nano-structures of Pd and CeO2 that promote the formation of the Pd-O-Ce interface provide optimal binding of both Had and OHad species aspects which are crucial for enhanced HOR kinetics. This review paper discusses the recent advances in Pd-CeO2 electrocatalysts for AEMFC anodes.

There have been many indices available in the process industries to describe rank or quantify hazards to people properties and environments. Most of the developed methods were meant to be applied to large scale and complex systems of process industries. Development of a swift and simple inherent safety index method which is relevant to small scale less complex membrane fuel cell system particularly the one in which to be applied during an early design stage is essential as an alternative to current comprehensive and yet time-consuming indices. In this work a modified version of PIIS modified prototype index for inherent safety (m-PIIS) was developed with the objectives of identifying indicating and estimating inherent safety of fuel cell system at an early design stage. The developed index was tested at four proton exchange membrane (PEM) fuel cell systems namely high pressure PEMFC system low pressure PEMFC system LH2 PEMFC system and on-board Me-OH PEMFC system. The developed index was also benchmarked against the original PIIS and ISI using the published results for the selection of process routes in MMA production. Results have indicated that m-PIIS has strong positive relationship with PIIS and ISI on most of the reaction step in MMA with the most significant are the C4 TBA and C3 reaction steps. Other reaction steps such as C2/MP C2/PA and ACH showed a strong positive relationship as well.