Publications

A best practice is a technique or methodology that has reliably led to a desired result. A wealth of experience regarding the safe use and handling of hydrogen exists as a result of an extensive history in a wide variety of industrial and aerospace settings. Hydrogen Safety Best Practices (www.h2bestpractices.org) captures this vast knowledge base and makes it publicly available to those working with hydrogen and related systems including those just starting to work with hydrogen. This online manual is organized under a number of hierarchical technical content categories. References including publications and other online links that deal with the safety aspects of hydrogen are compiled for easy access. This paper discusses the development of Hydrogen Safety Best Practices as a safety knowledge tool the nature of its technical content and the steps taken to enhance its value and usefulness. Specific safety event examples are provided to illustrate the link between technical content in the online best practices manual and a companion safety knowledge tool Hydrogen Incident Reporting and Lessons Learned (www.h2incidents.org) which encourages the sharing of lessons learned and other safety event information.

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.

If the hydrogen economy is to progress more hydrogen refuelling stations are required. In the short term in the absence of a hydrogen distribution network the most likely means of supplying the refuelling stations will be by liquid hydrogen road tanker. This development will clearly increase the number of tanker offloading operations significantly and these may need to be performed in more challenging environments with close proximity to the general public. The work described in this paper was commissioned in order to determine the hazards associated with liquid hydrogen spills onto the ground at rates typical for a tanker hose failure during offloading.

Experiments have been performed to investigate spills of liquid hydrogen at a rate of 60 litres per minute. Measurements were made on both unignited and ignited releases.

These include:

• Concentration of hydrogen in air thermal gradient in the concrete substrate liquid pool formation and temperatures within the pool
• Flame velocity within the cloud thermal radiation IR and visible spectrum video records.
• Sound pressure measurements
• An estimation of the extent of the flammable cloud was made from visual observation video IR camera footage and use of a variable position ignition source.

This review explores CO2 methanation and steam methane reforming (SMR) as two key thermochemical processes governed by reversible reactions each offering distinct contributions to carbon-neutral energy systems. The objective is to provide a comparative assessment of both processes highlighting how reaction reversibility can be strategically leveraged for decarbonization. The study addresses methane production via CO2 methanation and hydrogen production via SMR focusing on their thermodynamic behaviors catalytic systems environmental impacts and economic viability. CO2 methanation when powered by renewable hydrogen can result in emissions ranging from −471 to 1076 kg CO2-equivalent per MWh of methane produced while hydrogen produced from SMR ranges from 90.9 to 750.75 kg CO2-equivalent per MWh. Despite SMR’s lower production costs (USD 21–69/MWh) its environmental footprint is considerably higher. In contrast methanation offers environmental benefits but remains economically uncompetitive (EUR 93.53–204.62/MWh). Both processes rely primarily on Ni-based catalysts though recent developments in Ru-based and bimetallic systems have demonstrated improved performance. The review also examines operational challenges such as carbon deposition and catalyst deactivation. By framing these technologies through the shared lens of reversibility this work outlines pathways toward integrated efficient and circular energy systems aligned with long-term sustainability and climate neutrality goals.

The BMW Hydrogen 7 is the world’s first premium sedan with a bi-fuelled internal combustion engine concept that has undergone the series development process. This car also displays the BMW typical driving pleasure. During development the features of the hydrogen energy source were emphasized. Engine tank system and vehicle electronics were especially developed as integral parts of the vehicle for use with hydrogen. The safety-oriented development process established additional strict hydrogen-specific standards for the Hydrogen 7. The fulfilment of these standards were demonstrated in a comprehensive experimentation and testing program which included all required tests and a large number of additional hydrogen-specific crash tests such as side impacts to the tank coupling system or rear impacts. Furthermore the behaviour of the hydrogen tank was tested under extreme conditions for instance in flames and after strong degradation of the insulation. Testing included over 1.7 million km of driving; and all tests were passed successfully proving the intrinsic safety of the vehicle and also confirming the success of the safety-oriented development process which is to be continued during future vehicle development. A safety concept for future hydrogen vehicles poses new challenges for vehicles and infrastructure. One goal is to develop a car fuelled by hydrogen only while simultaneously optimizing the safety concept. Another important goal is removal of (self-imposed) restrictions for parking in enclosed spaces such as garages. We present a vision of safety standards requirements and a program for fulfilling them.

INERIS has set up large-scale fully instrumented experiments to study the formation of flammable clouds resulting from a finite duration spillage of hydrogen in a quiescent room (80 m3 chamber). Concentration temperature and mass flow measurements were monitored during the release period and several hours after. Experiments were carried out for mass flow rates ranging from 02 g/s to 1 g/s. The instrumentation allowed the observation and quantification of rich hydrogen layers stratification effects. This paper presents both the experimental facility and the test results. These experimental results can be used to assess and benchmark CFD tools capabilities.

A study of open literature was performed to determine the effects of high hydrogen purity and gas pressure (in the range of 700-1000 bar) on the hydrogen embrittlement of several metallic materials. A particular focus was given to carbon low-alloy and stainless steels but information on embrittlement of aluminum and copper was included in the study. Additionally the most common test methods were studied and results from similar tests are presented in a manner so as to simplify comparisons of materials. Finally suggestions are provided for future testing necessary to ensure the safety of hydrogen storage at 700 bar.

It has been suggested that separation or safety distances for pressurised hydrogen storage can be reduced by the inclusion of walls or barriers between the hydrogen storage and vulnerable plant or other items. Various NFPA codes (1) suggest the use of 60° inclined fire barriers for protection against jet flames in preference to vertical ones.<br/>This paper describes a series of experiments performed in order to compare the performance of 60° barriers with that of 90° barriers. Their relative efficiency at protecting from thermal radiation and blast overpressure was measured together with the propensity for the thermal radiation and blast overpressure to be reflected back to the source of the leak. The work was primarily focused on compressed H2 storage for stationary fuel cell systems which may be physically separated from a fuel cell system or could be on board such a system. Different orifice sizes were used to simulate different size leaks and all releases were made were from storage at 200 bar.<br/>Overall conclusions on barrier performance were made based on the recorded measurements.

This is the tenth consecutive year of the World Energy Council’s (the Council) annual survey of key challenges and opportunities facing energy leaders in managing and shaping Energy Transitions. This year’s Issues Monitor report provides seven global maps six regional maps and fifty national maps.

These maps have been developed by analysing the responses of nearly 2300 energy leaders drawn from across the Council’s diverse and truly global energy community.

The Council’s Issues Monitor identifies the strategic energy landscape of specific countries and regions in the world through an analysis of 42 energy issues and 4 digitalisation-specific issues affecting the energy system. It provides a unique reality check and horizon scanning of persistent and emerging concerns involved in whole energy systems transition. This year’s report welcomes a significant increase in both the participation of global leaders (up over 75% from 1300 to nearly 2300) as well as the participation of 86 countries.

Each Issue Map provides a visual snapshot of the uncertainties and action priorities that energy policymakers CEOs and leading experts strive to address to shape and manage successful Energy

Transitions. Maps can be used in the following ways:

• To promote a shared understanding of successful Energy Transitions
• To appreciate and contrast regional variations to better understand differing priorities and areas of concern
• To follow the evolution of specific technology trends related to the energy sector

Solid state materials such as metal and chemical hydrides have been proposed and developed for high energy density automotive hydrogen storage applications. As these materials are implemented into hydrogen storage systems developers must understand their behavior during accident scenarios or contaminated refueling events. An ability to predict thermal and chemical processes during contamination allows for the design of safe and effective hydrogen storage systems along with the development of appropriate codes and standards. A model for the transport of gases within an arbitrary-geometry reactive metal hydride bed (alane -AlH3) is presented in this paper. We have coupled appropriate Knudsen-regime permeability models for flow through packed beds with the fundamental heat transfer and chemical kinetic processes occurring at the particle level. Using experimental measurement to determine and validate model parameters we have developed a robust numerical model that can be utilized to predict processes in arbitrary scaled-up geometries during scenarios such as breach-in-tank or contaminated refueling. Results are presented that indicate the progression of a reaction front through a compacted alane bed as a result of a leaky fitting. The rate of this progression can be limited by; 1) restricting the flow of reactants into the bed through densification and 2) maximizing the rate of heat removal from the bed.