France

In the framework of the HYTUNNEL-CS European project sponsored by FCH-JU a set of preliminary tests were conducted in a real tunnel in France. These tests are devoted to safety of hydrogen-fueled vehicles having a compressed gas storage and Temperature Pressure Release Device (TPRD). The goal of the study is to develop recommendations for Regulations Codes and Standards (RCS) for inherently safer use of hydrogen vehicles in enclosed transportation systems. In these preliminary tests the helium gas has been employed instead of hydrogen. Upward and downward gas releases following by TPRD activation has been considered. The experimental data describing local behavior (close to jet or below the chassis) as well as global behavior at the tunnel scale are obtained. These experimental data are systematically compared to existing engineering correlations. The results will be used for benchmarking studies using CFD codes. The hydrogen pressure range in these preliminary tests has been lowered down to 20MPa in order to verify the capability of various large-scale measurement techniques before scaling up to 70MPa the subject of the second campaign.

Promoted by national and European investment plans promoting the use of hydrogen as energy carrier the number of Gaseous Hydrogen Fueling Station (or GHFS) has been growing up quite significantly over the past years. Considering the new possible hazards and the related accidents induced by these installations like seen in 2019 in Norway this paper presents a risk assessment of a typical GHFS using the same methodology as the one required in France by the authorities for Seveso facilities. The fact that a hydrogen fueling station could be used by a public not particularly trained to handle hydrogen underlines the importance of this risk assessment. In this article typical components related to GHFS (dispenser high pressure storage compressor low pressure storage) are listed and the hazard potentials linked to these components and the substances involved are identified. Based on these elements and an accidentology a risk analysis has been conducted in order to identify all accidental situations that could occur. The workflow included a detailed risk assessment consisting in modeling the thermal and explosion effects of all hazardous phenomena and in assessing the probability of occurrence for these scenarios. Regarding possible mitigation measures the study was based on an international benchmark for codes and standards made for GFHS. These preliminary outcomes of this study may be useful for any designer and/or owner of a GFHS.

In the framework of the HYTUNNEL-CS European project sponsored by FCH-JU a set of preliminary tests were conducted in a real tunnel in France. These tests are devoted to safety of hydrogen-fueled vehicles having a compressed gas storage and Temperature Pressure Release Device (TPRD). The goal of the study is to develop recommendations for Regulations Codes and Standards (RCS) for inherently safer use of hydrogen vehicles in enclosed transportation systems. Two scenarios were investigated (a) jet fire evolution following the activation of TPRD due to conventional fuel car fire and (b) explosion of compressed hydrogen tank. The obtained experimental data are systematically compared to existing engineering correlations. The results will be used for benchmarking studies using CFD codes. The hydrogen pressure range in these preliminary tests has been lowered down to 20MPa in order to verify the capability of various large-scale measurement techniques before scaling up to 70 MPa the subject of the second experimental campaign.

Explosion venting is a prevention/mitigation solution widely used in the process industry to protect indoor equipment or buildings from excessive internal pressure caused by an accidental explosion. Vented explosions are widely investigated in the literature for various geometries hydrogen/air concentrations ignition positions initial turbulence etc. In real situations the vents are normally covered by a vent panel. In the case of an indoor leakage the hydrogen/air cloud will be stratified rather than homogeneous. Nowadays there is a lack in understanding about the vented explosion of stratified clouds and about the influence of vent cover inertia on the internal overpressure. This paper aims at shedding light on these aspects by means of experimental investigation of vented hydrogen/air deflagration using an experimental facility of 1m3 and via numerical simulations using the computational fluid dynamics (CFD) code FLACS

In industry handling hydrogen explosion presents a potential danger due to its effects on people and property. In the nuclear industry this explosion which is possible during severe accidents can challenge the reactor containment and it may lead to a release of radioactive materials into the environment. The Three Mile Island accident in the United States in 1979 and more recently the Fukushima accident in Japan have highlighted the importance of this phenomenon for a safe operation of nuclear installations as well as for the accident management.<br/>In 2013 the French Research Agency (ANR) launched the MITHYGENE project with the main aim of improving knowledge on hydrogen risk for the benefit of reactor safety. One of the topics in this project is devoted to the effect of hydrogen explosions on solid structures. In this context CEA conducted a test program with its SSEXHY facility to build a database on deformations of simple structures following an internal hydrogen explosion. Different regimes of explosion propagation have been studied ranging from detonation to slow deflagration. Different targets were tested such as cylinders and plates of variable thickness and diameter. Detailed instrumentation was used to obtain data for the validation of coupled CFD models of combustion and structural dynamics.<br/>This article details the experimental set-up and the results obtained. A companion article focuses on the comparison between these experimental results and the prediction of CFD numerical models

If Hydrogen is expected to be highly valuable some improvements should be conducted mainly regarding the storage safety. To prevent from high pressure hydrogen composite tanks bursting the comprehension of the thermo-mechanics phenomena in the case of fire should be improved. To understand the kinetic of strength loss the heat flux produced by fire of various intensities should be assessed. This is the objective of this real scale experimental campaign which will allow studying in future works the strength loss of composite high-pressure vessels in similar fire conditions to the ones determined in this study. Fire calibration tests were performed on metallic cylinder vessels. These tests with metallic cylinders are critical in the characterization of the thermal load of various fire sources (pool fire propane gas fire hydrogen gas fire) so as to evaluate differences related to different thermal load. Radiant panels were also used as thermal source for reference of pure radiation heat transfer. The retained thermal load might be representative of accidental situations in worst case scenarios and relevant for a standardized testing protocol. The tests performed show that hydrogen gas fires and heptane pool fire allow reaching the target in terms of absorbed energy regarding the results of risk analysis performed previously. Other considerations can be taken into account that will led to retain an hydrogen gas fire for further works. Firstly hydrogen gas fire is the more realistic scenario: Hydrogen is the combustible that we every time find near an hydrogen storage. Secondly as one of the objectives of the project is to make recommendations for standardization issues it’s important to note that gas fires are not too complex to calibrate control and reproduce. Finally due to previous considerations Hydrogen gas fire will be retained for thermal load of composite cylinders in future works.

Gaseous hydrogen for fuel cell electric vehicles must meet quality standards such as ISO 14687:2019 which contains maximal control thresholds for several impurities which could damage the fuel cells or the infrastructure. A review of analytical techniques for impurities analysis has already been carried out by Murugan et al. in 2014. Similarly this document intends to review the sampling of hydrogen and the available analytical methods together with a survey of laboratories performing the analysis of hydrogen about the techniques being used. Most impurities are addressed however some of them are challenging especially the halogenated compounds since only some halogenated compounds are covered not all of them. The analysis of impurities following ISO 14687:2019 remains expensive and complex enhancing the need for further research in this area. Novel and promising analyzers have been developed which need to be validated according to ISO 21087:2019 requirements.

Efficient storage of hydrogen is crucial for the success of hydrogen energy markets. 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 compressed hydrogen storage technologies focusing on high pressure storage tanks in metal and in composite materials. It details specific issues and constraints related to the materials and structure behavior in hydrogen and conditions representative of hydrogen energy uses. This paper is an update of the 2019 version that was presented in Australia. It especially covers recent progress made regarding regulations codes and standards for the design manufacturing periodic inspection and plastic materials’ evaluation of compressed hydrogen storage.

This paper evaluates the potential of grid services in France Italy Norway and Spain to provide an alternative income for electrolysers producing hydrogen from wind power. Grid services are simulated with each country's data for 2017 for energy prices grid services and wind power profiles from relevant wind parks. A novel metric is presented the value of curtailed hydrogen which is independent from several highly uncertain parameters such as electrolyser cost or hydrogen market price. Results indicate that grid services can monetise the unused spare capacity of electrolyser plants improving their economy in the critical deployment phase. For most countries up-regulation yields a value of curtailed hydrogen above 6 V/kg over 3 times higher than the EU's 2030 price target (without incentives). However countries with large hydro power resources such as Norway yield far lower results below 2 V/kg. The value of curtailed hydrogen also decreases with hydrogen production corresponding to the cases of symmetric and down-regulation.

The share of electrical energy from renewable sources has increased considerably in recent years in an attempt to reduce greenhouse gas emissions. To mitigate the uncertainties of these sources and to balance energy production with consumption an energy storage system (ESS) based on water electrolysis to produce hydrogen is studied. It can be applied to AC microgrids where several renewable energy sources and several loads may be connected which is the focus of the study. When excess electricity production is converted into hydrogen via water electrolysis low DC voltages and high currents are applied which needs specific power converters. The use of a three-phase buck-type current source converter in a single conversion stage allows for an adjustable DC voltage to be obtained at the terminals of the electrolyzer from a three-phase AC microgrid. The voltage control is preferred to the current control in order to improve the durability of the system. The classical control of the buck-type rectifier is generally done using two loops that correspond only to the control of its output variables. The lack of control of the input variables may generate oscillations of the grid current. Our contribution in this article is to propose a new control for the buck-type rectifier that controls both the input and output variables of the converter to avoid these grid current oscillations without the use of active damping methods. The suggested control method is based on an approach using the flatness properties of differential systems: it ensures the large-signal stability of the converter. The proposed control shows better results than the classical control especially in oscillation mitigation and dynamic performances with respect to the rejection of disturbances caused by a load step.