United States
Designing an Inherently Safe H2 Infrastructure: Combining Analytical, Experimental, and Numerical Investigations to Optimize H2 Refuelling Stations Safety by Passive Mitigation
Sep 2023
Publication
Natural ventilation is a well-known passive mitigation method to limit hydrogen build-up in confined spaces in case of accidental release [1-3]. In most cases a basic design of H2 infrastructure is adopted and vents installed for natural ventilation are adjusted according to safety targets and constraints of the considered structure. With the growing H2 mobility market the demand for H2 refueling infrastructure in our urban environment is on the rise. In order to meet both safety requirements and societal acceptance the design of such infrastructure is becoming more important. In this study a novel design concept is proposed for the hydrogen refueling station (HRS) by modifying physical structure while keeping safety consideration as the top priority of the concept. In this collaborative project between Air Liquide and the University of Delaware an extensive evaluation was performed on new structures of the processing container and dispenser of HRS by integrating safety protocols via passive means. Through a SWOT analysis combined with the most relevant approaches including analytical engineering models numerical simulations [4] and dedicated experimental trials an optimized design was obtained and its safety enhancement was fully evaluated. A small-scale processing container and an almost full-scale dispenser were built and tested to validate the design concepts by simulating accidental H2 release scenarios and assessing the associated consequences in terms of accumulation and potential flammable volumes formation. A conical dispenser and a V-shaped roof-top processing container which were easy to build and implement were designed and tested for this proof-of-concept study. This unique methodology from conception fundamental analysis investigation and validation through experimental design execution and evaluation is fully described in this study.
Examining the Nature of Two-dimensional Transverse Waves in Marginal Hydrogen Detonations using Boundary Layer Loss Modeling with Detailed Chemistry
Sep 2023
Publication
Historically it has been a challenge to simulate the experimentally observed cellular structures and marginal behavior of multidimensional hydrogen-oxygen detonations in the presence of losses even with detailed chemistry models. Very recently a quasi-two-dimensional inviscid approach was pursued where losses due to viscous boundary layers were modeled by the inclusion of an equivalent mass divergence in the lateral direction using Fay’s source term formulation with Mirels’ compressible boundary layer solutions. The same approach was used for this study along with the inclusion of thermally perfect detailed chemistry in order to capture the correct ignition sensitivity of the gas to dynamic changes in the thermodynamic state behind the detonation front. In addition the strength of transverse waves and their impact on the detonation front was investigated. Here the detailed San Diego mechanism was applied and it has been found that the detonation cell sizes can be accurately predicted without the need to prescribe specific parameters for the combustion model. For marginal cases where the detonation waves approach their failure limit quasi-stable mode behavior was observed where the number of transverse waves monotonically decreased to a single strong wave over a long enough distance. The strong transverse waves were also found to be slightly weaker than the detonation front indicating that they are not overdriven in agreement with recent studies.
Overview of International Activities in Hydrogen System Safety in IEA Hydrogen TCP Task 43
Sep 2023
Publication
Safety and reliability have long been recognized as key issues for the development commercialization and implementation of new technologies and infrastructure and hydrogen systems are no exception to this rule. Reliability engineering quantitative risk assessment (QRA) and knowledge exchange each play a key role in proactive addressing safety – before problems happen – and help us learn from problems if they happen. Many international research activities are focusing on both reliability and risk assessment for hydrogen systems. However the element of knowledge exchange is sometimes less visible. To support international collaboration and knowledge exchange the International Energy Agency (IEA) convened a new Technology Collaboration Program “Task 43: Safety and Regulatory Aspects of Emerging Large Scale Hydrogen Energy Applications” started in June 2022. Within Task 43 Subtask E focuses on Hydrogen Systems Safety. This paper discusses the structure of the Hydrogen Systems Safety subtask and the aligned activities and introduces opportunities for future work.
Social Risk Approach for Assessing Public Safety of Large-scale Hydrogen Systems
Sep 2023
Publication
Social risk is a comprehensive concept that considers not only internal/external physical risks but also risks (which are multiple varied and diverse) associated with social activity. It should be considered from diverse perspectives and requires a comprehensive evaluation framework that takes into account the synergistic impact of each element on others rather than evaluating each risk individually. Social risk assessment is an approach that is not limited to internal system risk from an engineering perspective but also considers the stakeholders development stage and societal readiness and resilience to change. This study aimed to introduce a social risk approach to assess the public safety of large-scale hydrogen systems. Guidelines for comprehensive social risk assessment were developed to conduct appropriate risk assessments for advanced science and technology activities with high uncertainties to predict major impacts on society before an accident occurs and to take measures to mitigate the damage and to ensure good governance are in place to facilitate emergency response and recovery in addition to preventive measures. In a case study this approach was applied to a hydrogen refueling station in Japan and risk-based multidisciplinary approaches were introduced. These approaches can be an effective supporting tool for social implementation with respect to large-scale hydrogen systems such as liquefied hydrogen storage tanks. The guidelines for social risk assessment of large-scale hydrogen systems are under the International Energy Agency Technology Collaboration Program Hydrogen Safety Task 43. This study presents potential case studies of social risk assessment for large-scale hydrogen systems for future.
Developing a Generalized Framework for Assessing Safety of Hydrogen Vehicles in Tunnels
Sep 2023
Publication
For widespread adoption of hydrogen fuel cell powered vehicles such vehicles need to be able to provide similar transportation capabilities as their gasoline/diesel powered counterparts. Meeting this requirement in many regions will necessitate access to tunnels. Previous work completed at Sandia National Laboratories provided high-fidelity consequence modeling of hydrogen vehicle tunnel crashes for a specific fire scenario in selected Massachusetts tunnels. To consider additional tunnels a generalized tunnel safety analysis framework is being developed. This framework aims to be broader than specific fire scenarios in specific tunnels allowing it to be applied to a range of tunnel geometries vehicle types and crash scenarios. Initial steps in the development of the generalized framework are reported within this work. Representative tunnel characteristics are derived based on data for tunnels in the U.S. Tunnel dimensions shapes and traffic levels are among the many characteristics reported within the data that can be used to inform crash scenario specification. Various crash scenario parameters are varied using lower-fidelity consequence modeling to quantify the impact on resulting safety hazards for time-dependent releases. These lower-fidelity models consider the unignited dispersion of hydrogen gas the thermal effects of jet fires and potential impacts of overpressures. Different sizes/classes of vehicles are considered as the total amount of hydrogen onboard may greatly affect scenario-specific consequences. The generalized framework will allow safety assessments to be both more agile and consistent when applied to different types of tunnels.
Design for Reliability and Safety: Challenges and Opportunities in Hydrogen Mobility Assets
Sep 2023
Publication
Safety and reliability are important performance attributes of any engineered system where humanmachine interactions are present. However they are usually approached as afterthoughts or in some cases unintended consequences of the system design and development process that must be addressed and verified in subsequent design stages. In plain words safety and reliability are often seen as constraints that add layers of complexity and extra costs to the minimum functional system of interest. No longer. Shell Hydrogen is embedding the Design for Reliability and Safety approach to engineer our products and assets in such a way that safety and reliability are at the core of a concurrent engineering process throughout the system lifecycle. This has been achieved in practice by leveraging systems reliability and safety engineering methods along with the experience and expertise of Shell Hydrogen original equipment manufacturers and system integrators in designing building and operating hydrogen assets for mobility applications.<br/>The challenges in implementing this approach are many ranging from access to historical data on equipment and component safety and reliability performance to lack of standardization in the industry when dealing with hydrogen related hazards. In this paper we will describe the approach in more detail some of our early successes and failures during deployment and the continual improvement journey that lies ahead.
Very Low-cost Wireless Hydrogen Leak Detection for Hydrogen Infrastructure
Sep 2023
Publication
A unique hydrogen leak detection strategy is the use of powerless indicator wraps for fittings and other pneumatic elements within a hydrogen facility. One transduction mechanism of such indicators is a color change that is induced by a reaction between a pigment and released hydrogen. This is an effective way to detect hydrogen leaks and to identify their source before they become a safety event however this technology requires visual (manual) inspection to identify a color change or leak. One improvement in this strategy would be to improve the communication of the visual response to an end-user. Element One (E1) has previously developed and introduced DetecTape® a self-fusing silicone non-reversible hydrogen leak detecting tape for application to potential leak sites in hydrogen piping valves and fittings and it has been successfully commercialized with excellent feedback. Element One’s sensors can be fabricated using either pigments or thin films which both change color and conductivity. Neither change requires an external power source. The conductivity change may be communicated as a wireless transmission such as passive radio frequency identification devices (RFID) to an appropriate receiving system where it may be remotely monitored to achieve higher levels of safety and reliability at low cost. Element One will report on its recent progress in the commercial development of remotely monitored hydrogen leak detection using several wireless protocols including passive RFID.
Fuel Cell Vehicle Hydrogen Emissions Testing
Sep 2023
Publication
The NREL Hydrogen Sensor Laboratory is comprised of researchers dedicated to furthering hydrogen sensor technology and detection methodology. NREL has teamed up with researchers at Environment and Climate Change Canada (ECCC) and Transport Canada (TC) to conduct research to quantify hydrogen emissions from Fuel Cell Electric Vehicles (FCEV). Test protocols will have a large effect on monitoring and regulating the hydrogen emissions from FCEVs. How emissions are tested will play an important role when understanding the safety and environmental implications of using FCEVs. NREL Sensor Laboratory personnel have partnered with other entities to conduct multiple variations of emissions testing for FCEVs. This experimentation includes testing different models of FCEVs under various driving conditions while monitoring the hydrogen concentration of the exhaust using several different test methods and apparatus. Researchers look to support regulatory bodies by providing useful data that can support more consistent and relevant safety and environmental standards. We plan to present on the current test methods and results from recent emissions measurements at ECCC.
Engineering Models for Refueling Protocol Development: Validation and Recommendations
Sep 2023
Publication
Fouad Ammouri,
Nicola Benvenuti,
Elena Vyazmina,
Vincent Ren,
Guillaume Lodier,
Quentin Nouvelot,
Thomas Guewouo,
Dorine Crouslé,
Rony Tawk,
Nicholas Hart,
Steve Mathison,
Taichi Kuroki,
Spencer Quong,
Antonio Ruiz,
Alexander Grab,
Alexander Kvasnicka,
Benoit Poulet,
Christopher Kutz and
Martin Zerta
The PRHYDE project (PRotocol for heavy duty HYDrogEn refueling) funded by the Clean Hydrogen partnership aims at developing recommendations for heavy-duty refueling protocols used for future standardization activities for trucks and other heavy duty transport systems applying hydrogen technologies. Development of a protocol requires a validated approach. Due to the limited time and budget the experimental data cannot cover the whole possible ranges of protocol parameters such as initial vehicle pressure and temperature ambient and precooling temperatures pressure ramp refueling time hardware specifications etc. Hence a validated numerical tool is essential for a safe and efficient protocol development. For this purpose engineering tools are used. They give good results in a very reasonable computation time of several seconds or minutes. These tools provide the heat parameters estimation in the gas (volume average temperature) and 1D temperature distribution in the tank wall. The following models were used SOFIL (Air Liquide tool) HyFill (by ENGIE) and H2Fills (open access code by NREL). The comparison of modelling results and experimental data demonstrated a good capability of codes to predict the evolution of average gas temperature in function of time. Some recommendations on model validation for the future protocol development are given.
Investigation of the Suitability of Viper: Blast CFD Software for Hydrogen and Vapor Cloud Explosions
Sep 2023
Publication
Many simplified methods for estimating blast loads from a hydrogen or vapor cloud explosion are unable to take into account the accurate geometry of confining spaces obstacles or landscape that may significantly interact with the blast wave and influence the strength of blast loads. Computation fluid dynamics (CFD) software Viper::Blast which was originally developed for the simulation of the detonation of high explosives is able to quickly and easily model geometry for blast analyses however its use for vapor cloud explosions and deflagrations is not well established. This paper describes the results of an investigation into the suitability of Viper::Blast for use in modeling hydrogen deflagration and detonation events from various experiments in literature. Detonation events have been captured with a high degree of detail and relatively little uncertainty in inputs while deflagration events are significantly more complex. An approach is proposed that may allow for a reasonable bounding of uncertainty potentially leading to an approach to CFD-based Monte Carlo analyses that are able to address a problem’s true geometry while remaining reasonably pragmatic in terms of run-time and computational investment. This will allow further exploration of practical CFD application to inform hydrogen safety in the engineering design assessment and management of energy mobility and transport systems infrastructure and operations.
A Novel Hydrogen Supply Chain Optimization Model - Case Study of Texas and Louisiana
Jun 2024
Publication
The increasing political momentum advocating for decarbonization efforts has led many governments around the world to unveil national hydrogen strategies. Hydrogen is viewed as a potential enabler of deep decarbonization notably in hard-to-abate sectors such as the industry. A multi-modal hourly resolved linear programming model was developed to assess the infrastructure requirements of a low-carbon supply chain over a large region. It optimizes the deployment of infrastructure from 2025 up to 2050 by assessing four years: 2025 2030 2040 and 2050 and is location agnostic. The considered infrastructure encompasses several technologies for production transmission and storage. Model results illustrate supply chain requirements in Texas and Louisiana. Edge cases considering 100% electrolytic production were analyzed. Results show that by 2050 with an assumed industrial demand of 276 TWh/year Texas and Louisiana would require 62 GW of electrolyzers 102 GW of onshore wind and 32 GW of solar panels. The resulting levelized cost of hydrogen totaled $5.6–6.3/kgH2 in 2025 decreasing to $3.2–3.5/ kgH2 in 2050. Most of the electricity production occurs in Northwest Texas thanks to high capacity factors for both renewable technologies. Hydrogen is produced locally and transmitted through pipelines to demand centers around the Gulf Coast instead of electricity being transmitted for electrolytic production co-located with demand. Large-scale hydrogen storage is highly beneficial in the system to provide buffer between varying electrolytic hydrogen production and constant industrial demand requirements. In a system without low-cost storage liquid and compressed tanks are deployed and there is a significant renewable capacity overbuild to ensure greater electrolyzer capacity factors resulting in higher electricity curtailment. A system under carbon constraint sees the deployment of natural gas-derived hydrogen production. Lax carbon constraint target result in an important reliance on this production method due to its low cost while stricter targets enforce a great share of electrolytic production.
No more items...