Publications

Introduction and commercialisation of hydrogen as an energy carrier of the future make great demands on all aspects of safety. Safety is a critical issue for innovations as it influences the economic attractiveness and public acceptance of any new idea or product. However research and safety expertise related to hydrogen is quite fragmented in Europe. The vision of a significant increased use of hydrogen as an energy carrier in Europe could not go ahead without strengthening and merging this expertise. This was the reason for the European Commission to support the launch on the first of March 2004 of a so-called Network of Excellence (NoE) on hydrogen safety: HySafe.

For decades risk assessment has been an important tool in risk management of activities in several industries world wide. It provides among others authorities and stakeholders with a sound basis for creating awareness about existing and potential hazards and risks and making decisions related to how they can prioritise and plan expenditures on risk reduction. The overall goal of the ongoing HySafe project is to contribute to the safe transition to a more sustainable development in Europe by facilitating the safe introduction of hydrogen technologies and applications. An essential element in this is the demonstration of safety: that all safety aspects related to production transportation and public use are controlled to avoid that introducing hydrogen as energy carrier should pose unacceptable risk to the society.<br/>History has proven that introducing risk analysis to new industries is beneficial e.g. in transportation and power production and distribution. However this will require existing methods and standards to be adapted to the specific applications. Furthermore when trying to quantify risk it is of utmost importance to have access to relevant accident and incident information. Such data may in many cases not be readily available and the utilisation of them will then require specific and long lasting data collection initiatives.<br/>In this paper we will present the work that has been undertaken in the HySafe project in developing methodologies and collecting data for risk management of hydrogen infrastructure. Focus is laid on the development of risk acceptance criteria and on the demonstration of safety and benefits to the public. A trustworthy demonstration of safety will have to be based on facts especially on facts widely known and emphasis will thus be put on the efforts taken to establish and operate a database containing hydrogen accident and incident information which can be utilised in risk assessment of hydrogen applications. A demonstration of safety will also have to include a demonstration of risk control measures and the paper will also present work carried out on safety distances and ignition source control.

The following paper describes researches to evaluate the behaviour under various accidental conditions of systems of transport compressed hydrogen. Particularly have been considered gaseous tube trailer and the packages cylinders employed for the road transport which have an internal gas pressures up to 200 barg.<br/>Further to a verification of the actual safety conditions this analysis intends to propose a theme that in the next future if confirmed projects around the employment of hydrogen as possible source energetic alternative could become quite important. The general increase of the consumptions of hydrogen and the consequently probable increase of the transports of gaseous hydrogen in pressure they will make the problem of the safety of the gaseous tube trail particularly important. Gaseous tube trailers will also use as components of plant. for versatility easy availability' and inexpensiveness.<br/>The first part of the memory is related to the analysis of the accidents happened in the last year in Italy with compressed hydrogen transports and particularly an accurate study has been made on the behaviour of a gaseous tube trailer involved in fire following a motorway accident in March 2003. In the central part of the job has been done a safety analysis of the described events trying to make to also emerge the most critical elements towards the activities developed by the teams of help intervened.<br/>Finally in the last part you are been listed on the base of the picked data a series of proposals and indications of the possible structural and procedural changes that could be suggested with the purpose to guarantee more elevated safety levels.

This paper presents a study on the Standard Operating Procedures (P.O.S.s) for the operation of the Fire Corps squads in the event of accidents with a hydrogen release fire or explosion. This study has been carried out by the Italian Working Group on the fire prevention safety issues as one of its main objectives. The Standard Operating Procedures proved to be a basic tool in order to improve the effectiveness of the Fire Corps rescue activity. The unique physical and chemical properties of the hydrogen its use without odorization and its almost invisible flame require a review of the already codified approaches to the rescue operations where conventional gases are involved. However this is only the first step; a Standard Operating Procedure puts together both the theoretical and practical experience achieved on the management of the rescue operations; therefore its arrangement is a cyclic process by nature always under continuous revision updating and improvement.

The EC funded Naturalhy project is investigating the possibility of promoting the swift introduction of hydrogen as a fuel by mixing hydrogen with natural gas and transporting this mixture by means of the existing natural gas pipeline system to end-users. Hydrogen may then be extracted for use in hydrogen fuel cell applications or the mixture may be used directly in conventional gas-fired equipment. This means that domestic customers would receive a natural gas (methane)/hydrogen mixture delivered to the home. As the characteristics of hydrogen are different from natural gas there may be an increased risk to end-users in the event of an accidental release of gas from internal pipe work or appliances. Consequently part of the Naturalhy project is aimed at assessing the potential implications on the safety of the public which includes end-users in their homes. In order to understand the nature of any gas accumulation which may form and identify the controlling parameters a series of large scale experiments have been performed to study gas accumulations within a 3 m by 3 m by 2.3 m ventilated enclosure representing a domestic room. Gas was released vertically upwards at a pressure typical of that experienced in a domestic environment from hole sizes representative of leaks and breaks in pipe work. The released gas composition was varied and included methane and a range of methane/hydrogen mixtures containing up to 50% hydrogen. During the experiments gas concentrations throughout the enclosure and the external wind conditions were monitored with time. The experimental data is presented. Analysis of the data and predictions using a model developed to interpret the experimental data show that both buoyancy and wind driven ventilation are important.

The SAE Technical Information Report (TIR) J2579 (Technical Information Report for Fuel Systems in Fuel Cell and Other Hydrogen Vehicles) has been created to address the safety performance of hydrogen storage and handling systems on vehicles. Safety qualification of the compressed hydrogen storage system is demonstrated through performance testing on prototype containment vessels. The two performance tests currently included in the SAE J2579 for evaluating unacceptable leakage and burst do not account for the potential effects of hydrogen embrittlement on structural integrity. This report describes efforts to address hydrogen embrittlement of structural metals in the framework of performance-based safety qualification. New safety qualification pathways that account for hydrogen embrittlement in the SAE J2579 include an additional pneumatic performance test using hydrogen gas or materials tests that demonstrate acceptable hydrogen embrittlement resistance of candidate structural metals.

Next generation of hydrogen energy based vehicles is expected to come into widespread use in the near future. Various topics related to hydrogen including production storage and application of hydrogen as an energy carrier have become subjects of discussion in the framework of various European and International projects. Safety information is vital to support the successful introduction into mainstream and public acceptance of hydrogen as an energy carrier. One of such issues which is seeking major attention is related to hydrogen powered vehicles parked inside a confined area (such as in a private garage). It is of utmost importance to predict if uncontrolled release of hydrogen from a vehicle parked inside a confined area can create an explosive atmosphere. Subsequently how the preventive measures can be implied to control these explosive atmospheres if present inside a confined area? There is a little guidance currently developed for confined areas accommodating hydrogen fuelled vehicles. It is essential that mitigation measures for such conditions become established.<br/>Characterization of different scenarios those may arise in a real situation from hydrogen fuelled vehicle parked inside a garage and furthermore the investigation of an optimal ventilation rate for hydrogen risk mitigation are some of the main objectives described in the framework of the present study. This work is an effort to provide detail experimental information’s in view of establishing guidelines for hydrogen powered vehicles parked inside a private garage. The present work is developed in the framework of a European Network of Excellence HySafe and French project DRIVE. Present paper describes a purpose built realistic Garage test facility at CEA to study the dispersion of hydrogen leakage. The studied test cases evaluate the influence of injected volumes of hydrogen and the initial conditions at the leakage source on the dispersion and mixing characteristics inside the free volume of the unventilated garage. The mixing process and build-up of hydrogen concentration is measured for the duration of 24 hours. Due to safety reasons helium gas is used to simulate the hydrogen dispersion characteristics.

In the problem of the protection by the consequences of an explosion is actual for many industrial application involving storage of gas like methane or hydrogen refuelling stations and so on. A simple and economic way to reduce the peak pressure associated to a deflagration is to supply to the confined environment an opportune surface substantially less resistant then the protected structure typically in stoichiometric conditions the peak pressure reduction is around the 8 bars for a generic hydrocarbon combustion in an adiabatic system lacking of whichever mitigation system. In general the problem is the forecast of the peak pressure value (PMAX) of the explosion. This problem is faced using CFD codes modelling the structure in which the explosion is located and setting the main parameters like concentration of the gas in the mixture the volume available the size of vent area and obstacles (if included) and so on. In this work the idea is to start from empirical data to train a Neural Network (NN) in order to find the correlation among the parameters regulating the phenomenon. Associated to this prediction a fuzzy model will provide to quantify the uncertainty of the predicted value.

The paper presents a complete value chain for the use of green hydrogen in a port facility. The main objective was to propose the sizing of the main components that make up green hydrogen to ensure the supply of 1 MWe in replacing the diesel generator. The energy demand required for the port was determined by establishing the leading small and large-scale conventional energyconsuming equipment. Hence 60 kgH2 was required to ensure the power supply. The total electrical energy to produce all the hydrogen was generated from photovoltaic solar energy considering threegeneration scenarios (minimum maximum and the annual average). In all cases the energy supply in the electrolyzer was 3.08 MWe. In addition the effect of generating in the port facility using a diesel generator and a fuel cell was compared. The cost of 1 kgH2 could be 4.09 times higher than the cost of 1 L of diesel meaning that the output kWh of each system is economically similar. In addition the value of electrical energy through a Power Purchase Agreement (PPA) was a maximum of 79.79 times the value of a liter of diesel. Finally the Levelized Cost of Energy (LCOE) was calculated for two conditions in which the MWe was obtained from the fuel cell without and with the photovoltaic solar plant.

When a hydrogen supply station is to be installed in Japan three fundamental laws must be taken into consideration: the High Pressure Gas Safety Law the Building Standards Law and the Fire Service Law. The High Pressure Gas Safety Law in particular regulates procedures for safety concerning hydrogen supply stations. This law came under review accompanying consideration of the potential utilization of fuel cell vehicles and hydrogen stations. At that time the Japan Petroleum Energy Center (JPEC) investigated safety technology for hydrogen supply stations and prepared a draft of the law. Since then a new combined gasoline/hydrogen supply station compliant with the revised law was established on December 2006. There are a large number of safety precautions incorporated into this station model which conform to the law. As a result of these modifications it was possible to reduce the safe setback distance. In this paper we present an overview of the new hydrogen supply station model the safety precautions and the regulations the station is based on.