The higher rate of component failure and downtime during initial operation in hydrogen stations is not well understood. The National Renewable Energy Laboratory (NREL) has been collecting failed components from retail and research hydrogen fueling stations in California and Colorado and analyzing them using an optical zoom and scanning electron microscope. The results show stainless steel metal particulate contamination. While it is difficult to definitively know the origin of the contaminants, a possible source of the metal particulates is improper tube cleaning practices. To understand the impact of different cleaning procedures, NREL performed an experiment to quantify the particulates introduced from newly cut tubes. The process of tube cutting, threading and bevelling, which is performed most often during station fabrication, is shown to introduce metal contaminants and thus is an area that could benefit from improved cleaning practices. This paper shows how these particulates can be reduced, which could prevent station downtime and costly repair. These results are from the initial phase of a project in which NREL intends to further investigate the sources of particulate contamination in hydrogen stations.

The aim of this study is to assess the probability of the damage to hydrogen fueling station personnel exposed to the hydrogen explosion shock wave. A three-dimensional mathematical model of the explosion of hydrogen-air cloud formed after the destruction of the high-pressure storage cylinders is developed. A computer technology how to define the personnel damage probability field on the basis of probit analysis of the generated shock wave is developed. To automate the process of computing the "probit function-damage probability" tabular dependence is replaced by a piecewise cubic spline. The results of calculations of overpressure fields, impulse loading, and the probability of damage to fueling station personnel exposed to the shock wave are obtained. The mathematical model takes into account the complex terrain and three-dimensional non-stationary nature of the shock wave propagation process. The model allows to obtain time-spatial distribution of damaging factors (overpressure in the shock wave front and the compression phase impulse) required to determine the three-dimensional non-stationary damage probability fields based on probit analysis. The developed computer technology allows to carry out an automated analysis of the safety situation at the fueling station and to conduct a comparative analysis of the effectiveness of different types of protective facilities

Although many studies have looked at safety issues relating to hydrogen fueling stations, few studies have analyzed the security risks, such as deliberate attack of the station by threats such as terrorists and disgruntled employees. The purpose of this study is to analyze security risks for a hydrogen fueling station with an on-site production of hydrogen from methylcyclohexane. We qualitatively conducted a security risk analysis using American Petroleum Institute Standard 780 as a reference for the analysis. The analysis identified 93 scenarios, including pool fires. We quantitatively simulated a pool fire scenario unique to the station to analyze attack consequences. Based on the analysis and the simulation, we recommend countermeasures to prevent and mitigate deliberate attacks.

This paper introduces a risk-based methodology for hydrogen refueling stations. Momentarily, four stations are present in the Netherlands. This number is expected to increase to around twenty in the next years. For these stations, a quantitative risk analysis (QRA) must be carried out to account for spatial planning. The presented method identifies the loss of containment scenarios and failure frequencies. Additionally, the results of this study may be used in legislative context in the form of fixed generic safety distances. Using the risk analysis tool Safeti-NL safety distances are determined for three different kinds of hydrogen refueling stations, distinguished by the supply method of the hydrogen. For the hydrogen refueling stations, a maximum safety distance of 35 m is calculated. However, despite the relatively small safety distances, the maximum effect distances (distance to 1% lethality) can be very large, especially for stations with a supply and storage of liquid hydrogen. The research was overseen by an advisory committee, which also provided technical information on the refueling stations.

Hydrogen has potential applications that require larger-scale storage, use, and handling systems than currently are employed in emerging-market fuel cell applications. These potential applications include hydrogen generation and storage systems that would support electrical grid systems. There has been extensive work evaluating regulations, codes, and standards (RCS) for the emerging fuel cell market, such as the infrastructure required to support fuel cell electric vehicles. However, there has not been a similar RCS evaluation and development process for these larger systems. This paper presents an evaluation of the existing RCS in the United States for large-scale systems and identifies potential RCS gaps. This analysis considers large-scale hydrogen technologies that are currently being employed in limited use but may be more widely used as large-scale applications expand. The paper also identifies areas of potential safety research that would need to be conducted to fill the RCS gaps. U.S. codes define bulk hydrogen storage systems but do not define large-scale systems. This paper evaluates potential applications to define a large-scale hydrogen system relative to the systems employed in emerging technologies such as hydrogen fuelling stations. These large-scale systems would likely be of similar size to or larger than industrial hydrogen systems.

In the United States, requirements for liquid motor vehicle fuelling stations have been in place for many years. Requirements for motor vehicle fuelling stations for gaseous fuels, including hydrogen, are relatively new. These requirements have, in the United States, been developed along different code and standards paths. The liquid fuels have been addressed in a single document and the gaseous fuels have been addressed in documents specific to an individual gas. The result of these parallel processes is that multi-fuel stations are subject to requirements in several fuelling regulations, codes, and standards (RCS). This paper describes a configuration of a multi-fuel motor vehicle fuelling station and provides a detailed breakdown of the codes and standards requirements. The multi-fuel station would dispense what the U.S. Department of Energy defines as the six key alternative fuels: biodiesel, electricity, ethanol, hydrogen, natural gas, and propane. The paper will also identify any apparent gaps in RCS and potential research projects that could help fill these gaps.

In this paper we focus on the term "Explosion", and its definitions from a societal, regulatory and scientific perspective. The experts involved in developing Regulations, Codes and Standards (RCS) are typically not combustion scientists. Conversely, combustion scientists are typically not involved in development of RCS. Yet, both sets of experts develop literature applicable to explosions. There are aspects, particularly related to the definitions associated with explosions, where improved consistency would be beneficial. We will demonstrate that these definitions are inconsistent. Of particular interest is how these definitions affect hydrogen technologies. This manuscript has its roots in combustion science and examines how the unique behavior of hydrogen in many circumstances motivates a closer look at relevant RCS definitions and terminology. We will point out ambiguities and how these lead to confusion in supporting definitions, and to overly restrictive RCS for hydrogen applications. We will then suggest internally self-consistent terminology which can serve as a starting point to develop consistent RCS definitions and requirements. These will, in turn, improve public and first responder safety, protect capital investment, and enable cost effective deployment of hydrogen technologies. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Numerical experiments are performed to understand different regimes of hydrogen nonpremixed combustion in an enclosure with passive ventilation through one horizontal or vertical vent located at the top of a wall. The Reynolds averaged Navier Stokes (RANS) computational fluid dynamics (CFD) model with a reduced chemical reaction mechanism is described in detail. The model is based on the renormalization group (RNG) k-s turbulence model, the eddy dissipation concept (EDC) model for simulation of combustion coupled with the 18-step reduced chemical mechanism (8 species), and the in-situ adaptive tabulation (ISAT) algorithm that accelerates the reacting flow calculations by two to three orders of magnitude. The analysis of temperature and species (hydroxyl, hydrogen, oxygen, water) concentrations in time, as well as the velocity through the vent, shed a light on regimes and dynamics of indoor hydrogen fires. A well-ventilated fire is simulated in the enclosure at a lower release flow rate and complete combustion of hydrogen within the enclosure. Fire becomes under-ventilated at higher release flow rates with two different modes observed. The first mode is the external flame stabilised at the enclosure vent at moderate release rates, and the second mode is the self-extinction of combustion inside and outside the enclosure at higher hydrogen release rates. The simulations demonstrated a complex reacting flow dynamics in the enclosure that leads to formation of the external flame or the self-extinction. The air intake into the enclosure at later stages of the process through the whole vent area is a characteristic feature of the self-extinction regime. This air intake is due to faster cooling of hot combustion products by sustained colder hydrogen leak compared to the generation of hot products by the ceasing chemical reactions inside the enclosure and hydrogen supply. In general, an increase of hydrogen sustained release flow rate will change fire regime from the well-ventilated combustion within the enclosure, through the external flame stabilised at the vent, and finally to the self-extinction of combustion throughout the domain.

Based on the increasing need of energy for the future and the related risks to the environments due to burning of fossils fuels, hydrogen is seen as an efficient and application related clean energy carrier that may be derived from renewable energy sources. A variety of applications connected with production and use of hydrogen and the related risks have been identified, and a survey has been conducted among a number of experts as an internet exercise for unveiling the potential lack of necessary knowledge in order to handle hydrogen in a safe way concerning the various applications.

The main results concern hazardous situations related to release and explosions of hydrogen in confined and semi-confined areas, tunnels and garages, and mitigation of hazardous situations, i.e. preventions of accidents and reduction of consequences from accidents happening anyway.

The response of a typical steel-lined reinforced concrete nuclear reactor containment to postulated internal hydrogen detonations is investigated by detailed axisymetric non-linear dynamic finite element analysis. The wall pressure histories are calculated for hydrogen detonations using a technique that reproduces the sharp discontinuity at the shock front. The pressure results can be applied to geometrically similar vessels. The analysis indicates that the response is more sensitive to the point of initiation than to the strength of the detonation. Approximate solutions based on a pure impulse assumption where the containment is modelled as a single-degree-of freedom (SDOF) system may be seriously unconservative. This work becomes relevant because new nuclear reactors are foreseen as a primary of source of hydrogen supply.