Publications

This paper analyzes the behavior of residential solar-powered electrical energy storage systems. For this purpose a simulation model based on MATLAB/Simulink is developed. Investigating both short-time and seasonal hydrogen-based storage systems simulations on the basis of real weather data are processed on a timescale of 15 min for a consideration period of 3 years. A sensitivity analysis is conducted in order to identify the most important system parameters concerning the proportion of consumption and the degree of self-sufficiency. Therefore the influences of storage capacity and of storage efficiencies are discussed. A short-time storage system can increase the proportion of consumption by up to 35 percentage points compared to a self-consumption system without storage. However the seasonal storing system uses almost the entire energy produced by the photovoltaic (PV) system (nearly 100% self-consumption). Thereby the energy drawn from the grid can be reduced and a degree of self-sufficiency of about 90% is achieved. Based on these findings some scenarios to reach self-sufficiency are analyzed. The results show that full self-sufficiency will be possible with a seasonal hydrogen-based storage system if PV area and initial storage level are appropriate.

Growing demand for individual and especially complex parts with emphasis on biomedical or lightweight applications enhances the importance of laser powder bed fusion. Magnesium alloys offer both biocompatibility and low density but feature a very high melting point of oxide layers while the evaporation temperature of pure magnesium is much lower. This impedes adequate part quality and process reproducibility. To weaken this oxide layer and enhance processability a 2 %-hydrogen-argon-gas atmosphere was investigated. A machine system was modified to the use of the novel inert gas to determine the influence of gas atmosphere on hollow cuboids and solid cubes. While processing a 20.3 % decrease in structure width and 20.6 % reduction in standard deviation of the cuboids was determined. There was no significate influence on relative density of solid cubes although eight of the ten highest density specimen were fabricated with the hydrogen addition.

The transition to a more sustainable personal transportation sector requires the widespread adoption of electric vehicles. However a dominant design has not yet emerged and a standards battle is being fought between battery and hydrogen fuel cell powered electric vehicles. The aim of this paper is to analyze which factors are most likely to influence the outcome of this battle thereby reducing the uncertainty in the industry regarding investment decisions in either of these technologies. We examine the relevant factors for standard dominance and apply a multi-criteria decision-making method best worst method to determine the relative importance of these factors. The results indicate that the key factors include technological superiority compatibility and brand reputation and credibility. Our findings show that battery powered electric vehicles have a greater chance of winning the standards battle. This study contributes to theory by providing further empirical evidence that the outcome of standards battles can be explained and predicted by applying factors for standard success. We conclude that technology dominance in the automotive industry is mostly driven by technological characteristics and characteristics of the format supporter.

The use of high-fidelity simulation methods based on large-eddy simulation (LES) are proving useful for understanding and mitigating the safety hazards associated with hydrogen releases from nuclear power plants. However accurate modelling of turbulent premixed hydrogen flames via LES can require very high resolution to capture both the large-scale turbulence and its interaction with the flame fronts. Standard meshing strategies can result in impractically high computational costs especially for the thin fronts of hydrogen flames. For these reasons the use of a recently formulated integral length scale approximation (ILSA) subfilter-scale model in combination with an efficient anisotropic block-based adaptive mesh refinement (AMR) technique is proposed and examined herein for performing LES of turbulent premixed hydrogen flames. The anisotropic AMR method allows dynamic and solution-dependent resolution of flame fronts and the grid-independent properties of the ILSA model ensure that numerical errors associated with implicitly-filtered LES techniques in regions with varying resolution are avoided. The combined approach has the potential to allow formally converged LES solutions (direct numerical simulation results are typically reached in the limit of very fine meshes with standard subgrid models). The proposed LES methodology is applied to combustion simulations of lean premixed hydrogen-air mixtures within closed vessels: a problem relevant to hydrogen safety applications in nuclear facilities. A progress variable-based method with a multi-phenomena burning velocity model is used as the combustion model. The present simulation results are compared to the available experiment data for several previously studied THAI vessel cases and the capabilities of the proposed LES approach are assessed.

The future of hydrogen energy is wrapped up with the future of natural gas renewable energy and carbon capture and storage (CCS). This yields useful synergies but also political economic and technical complexity. Nevertheless our survey of more than 1000 senior oil and gas professionals suggests a more certain future for hydrogen and that the time is right to begin scaling the hydrogen economy.

Energy transition is a part of a much wider Grand Transition which is not all about energy. Energy transition cannot be achieved all at once or by any one actor. Relying only on better energy modelling and forecasting to guide successful transition will be fatal even in a data-rich era.<br/>It is timely for energy leaders to ask:<br/>Are global energy scenarios achieving their potential in opening up action on new energy futures?<br/>How do the Council’s World Energy Scenarios compare with global energy outlooks scenarios and normative visions used by others and what can we learn by contrasting the increasing richness of energy futures thinking?<br/>In anticipation of the 24th World Energy Congress the Council is refreshing its global energy foresight and updating its global scenarios narratives. The focus is on an ‘innovation twist to 2040’ and the use of scenarios to explore and navigate new exponential growth opportunities for accelerating successful energy transition in an era of epic and disruptive innovation.<br/>As a part of the refresh the Council has conducted a comparison study of global energy scenarios in order to test the continued plausibility relevance and challenge of its own existing scenario set the World Energy Scenarios 2016 launched at the 23rd World Energy Congress in Istanbul in 2016.<br/>By comparing the methods narratives and assumptions associated with a benchmarkable set of global energy futures initiatives and studies the Council seeks to provide our members with clearer understanding and new insights on energy transition while preparing them to better engage with leadership dialogues which pivot on visions of a new energy future.<br/>The review also provides an opportunity to reflect on the challenges and obstacles for utilising global energy scenarios to drive impact and the challenges in bridging agile and flexible qualitative storytelling with long term quantitative energy modelling."

Hydrogen vehicles may emerge as a leading contender to replace today’s internal combustion engine powered vehicles. A Phenomena Identification and Ranking Table exercise conducted as part of the European Network of Excellence on Hydrogen Safety (HySafe) identified the use of hydrogen vehicles in road tunnels as a topic of important concern. An internal project called HyTunnel was duly established within HySafe to review identify and analyse the issues involved and to contribute to the wider activity to establish the true nature of the hazards posed by hydrogen vehicles in the confined space of a tunnel and their relative severity compared to those posed by vehicles powered by conventional fuels including compressed natural gas (CNG). In addition to reviewing current hydrogen vehicle designs tunnel design practice and previous research a programme of experiments and CFD modelling activities was performed for selected scenarios to examine the dispersion and explosion hazards potentially posed by hydrogen vehicles. Releases from compressed gaseous hydrogen (CGH2) and liquid hydrogen (LH2) powered vehicles have been studied under various tunnel geometries and ventilation regimes. The findings drawn from the limited work done so far indicate that under normal circumstances hydrogen powered vehicles do not pose a significantly higher risk than those powered by petrol diesel or CNG but this needs to be confirmed by further research. In particular obstructions at tunnel ceiling level have been identified as a potential hazard in respect to fast deflagration or even detonation in some circumstances which warrants further investigation. The shape of the tunnel tunnel ventilation and vehicle pressure relief device (PRD) operation are potentially important parameters in determining explosion risks and the appropriate mitigation measures.

Due to the nonideality of a high pressure hydrogen release the possibility of a two-phase flow and its effect on the dynamics of the discharge process was experimentally investigated. A small-scale facility was designed and constructed to simulate the transient blow-down of a cryogenic fluid through a small break. Gaseous and liquid nitrogen were planned to were used as a surrogate for GH2 and LH2. The results will complement the quasi-stationary safety regulation tests and will provide time-dependent data for verification of the theoretical models. Different orifice sizes (0.5 1 2 4 mm) and initial N2 pressures (30 – 200 bar) were used in the tests. The measured time-dependent data for vessel discharge pressure thrust discharge mass flow rate and gas temperatures were compared against a theoretical model for high pressure nitrogen release. This verification for nitrogen also assures the equation of state for hydrogen which is based on the same methodology.

This paper reports experimental results from a series of experiments in which gaseous hydrogen was released into a 31 m3 enclosure and the hydrogen concentrations at a number of points within the enclosure were monitored to assess whether hydrogen accumulation occurred and whether a homogeneous or stratified mixture was formed. The enclosure was located in the open air and therefore subject to realistic and therefore variable wind conditions. The hydrogen release rate and the passive vent arrangements were varied. The experiments were carried out as part of the EU Hyindoor Project.

Most experimental investigations of underexpanded hydrogen jets have been limited to circular nozzles in an attempt to better understand the fundamental jet-exit flow physics and model this behaviour with pseudo source models. However realistic compressed storage leak exit geometries are not always expected to be circular. In the present study jet dispersion characteristics from rectangular slot nozzles with aspect ratios from 2 to 8 were investigated and compared with an equivalent circular nozzle. Schlieren imaging was used to observe the jet-exit shock structure while quantitative Planar Laser Rayleigh Scattering was used to measure downstream dispersion characteristics. These results provide physical insight and much needed model validation data for model development.

This manuscript presents the results of a multi-lateral international activity intended to understand how to execute a cycle stress test as specified in a chosen standard (GTR SAE ISO EIHP …). The purpose of this work was to establish a harmonized test method protocol to ensure that the same results would be achieved regardless of the testing facility. It was found that accurate temperature measurement of the working fluid is necessary to ensure the test conditions remain within the tolerances specified. Continuous operation is possible with adequate cooling of the working fluid but this becomes more demanding if the cycle frequency increases. Recommendations for future test system design and operation are presented.

The efficiency of gas sensor application for facilitating the safe use of hydrogen depends to a considerable extent on the response time of the sensor to change in hydrogen concentration. The response and recovery times have been measured for five different hydrogen sensors three commercially available and two promising prototypes which operate at room temperature. Experiments according to ISO 26142 show that most of the sensors surpass much for a concentration change from clean to hydrogen containing air the demands of the standard for the response times t(90) and values of 2 to 16 s were estimated. For an opposite shift to clean air the recovery times t(10) are from 7 to 70 s. Results of transient behaviour can be fitted with an exponential approach. It can be demonstrated that results on transient behaviour depend not only from investigation method and the experimental conditions like gas changing rate and concentration jump as well as from operating parameters of sensors. In comparison to commercial MOS and MIS-FET hydrogen sensors new sensor prototypes operating at room temperature possesses in particular longer recovery times.

This paper describes research work that has been performed at LSBU using both a laminar burning velocity rig and a small scale cylindrical explosion vessel to explore the use of very fine water fog nitrogen dilution and sodium hydroxide additives in the mitigation of hydrogen deflagrations. The results of the work suggest that using a combination of the three measures together produces the optimal mitigation performance and can be extremely effective in: inhibiting the burning velocity reducing the rate of explosion overpressure rise and narrowing the flammability limits of hydrogen-oxygen-nitrogen mixtures.

Computational Fluid Dynamics (CFD) is applied to investigate the near exit jet behavior of high pressure hydrogen release into quiescent ambient air through different types of orifices. The size and geometry of the release hole can affect the possibility of auto-ignition. Therefore the effect of release geometry on the behavior and development of hydrogen jet issuing from non-axisymmetric (elliptical) and expanding orifices is investigated and compared with their equivalent circular orifices. A three-dimensional in-house code is developed using the MPI library for parallel computing to simulate the flow based on an inviscid approximation. Convection dominates viscous effects in strongly underexpanded supersonic jets in the vicinity of release exit justifying the use of the Euler equations. The transport (advection) equation is applied to calculate the concentration of hydrogen-air mixture. The Abel-Nobel equation of state is used because high pressure hydrogen flow deviates from the ideal gas assumption. This work effort is conducted to fulfill two objectives. First two types of circular and elliptic orifices with the same cross sectional area are simulated and the flow behavior of each case is studied and compared during the initial stage of release. Second the comparative study between expanding circular exit and its fixed counterpart is carried out. This evaluation is conducted for different sizes of nozzle with different aspect ratios.

The Department of Energy (DOE) Hydrogen Program Plan (the Program Plan or Plan) outlines the strategic high-level focus areas of DOE’s Hydrogen Program (the Program). The term Hydrogen Program refers not to any single office within DOE but rather to the cohesive and coordinated effort of multiple offices that conduct research development and demonstration (RD&D) activities on hydrogen technologies. This terminology and the coordinated efforts on hydrogen among relevant DOE offices have been in place since 2004 and provide an inclusive and strategic view of how the Department coordinates activities on hydrogen across applications and sectors. This version of the Plan updates and expands upon previous versions including the Hydrogen Posture Plan and the DOE Hydrogen and Fuel Cells Program Plan and provides a coordinated high-level summary of hydrogen related activities across DOE.



The 2006 Hydrogen Posture Plan fulfilled the requirement in the Energy Policy Act of 2005 (EPACT 2005) that the Energy Secretary transmit to Congress a coordinated plan for DOE’s hydrogen and fuel cell activities. For historical context the original Posture Plan issued in 2004 outlined a coordinated plan for DOE and the U.S. Department of Transportation to meet the goals of the Hydrogen Fuel Initiative (HFI) and implement the 2002 National Hydrogen Energy Technology Roadmap. The HFI was launched in 2004 to accelerate research development and demonstration (RD&D) of hydrogen and fuel cell technologies for use in transportation electricity generation and portable power applications. The Roadmap provided a blueprint for the public and private efforts required to fulfill a long-term national vision for hydrogen energy as outlined in A National Vision of America’s Transition to a Hydrogen Economy—to 2030 and Beyond. Both the Roadmap and the Vision were developed out of meetings involving DOE industry academia non-profit organizations and other stakeholders. The Roadmap the Vision the Posture Plans the 2011 Program Plan and the results of key stakeholder workshops continue to form the underlying basis for this current edition of the Program Plan.



This edition of the Program Plan reflects the Department’s focus on conducting coordinated RD&D activities to enable the adoption of hydrogen technologies across multiple applications and sectors. It includes content from the various plans and documents developed by individual offices within DOE working on hydrogen-related activities including: the Office of Fossil Energy's Hydrogen Strategy: Enabling a Low Carbon Economy the Office of Energy Efficiency and Renewable Energy’s Hydrogen and Fuel Cell Technologies Office Multi-year RD&D Plan the Office of Nuclear Energy’s Integrated Energy Systems 2020 Roadmap and the Office of Science’s Basic Research Needs for the Hydrogen Economy. Many of these documents are also in the process of updates and revisions and will be posted online.



Through this overarching document the reader will gain information on the key RD&D needs to enable the largescale use of hydrogen and related technologies—such as fuel cells and turbines—in the economy and how the Department’s various offices are addressing those needs. The Program will continue to periodically revise the Plan along with all program office RD&D plans to reflect technological progress programmatic changes policy decisions and updates based on stakeholder input and reviews.

The Hydrogen Safety Panel brings a broad cross-section of expertise from the industrial government and academic sectors to help advise the U.S. Department of Energy's (DOE) Fuel Cell Technologies Office through its work in hydrogen safety codes and standards. The Panel's initiatives in reviewing safety plans conducting safety evaluations identifying safety-related technical data gaps and supporting safety knowledge tools and databases cover the gamut from research and development to demonstration. The Panel's recent work has focused on the safe deployment of hydrogen and fuel cell systems in support of DOE efforts to accelerate fuel cell commercialization in early market applications: vehicle refuelling material handling equipment backup power for warehouses and telecommunication sites and portable power devices. This paper summarizes the work and learnings from the Panel's early efforts the transition to its current focus and the outcomes and conclusions from recent work on the deployment of hydrogen and fuel cell systems.

The challenges and approaches of the safety and risk management for the hydrogen production with nuclear-based thermochemical water splitting have been far from sufficiently reported as the thermochemical technology is still at a fledgling stage and the linkage of a nuclear reactor with a hydrogen production plant is unprecedented. This paper focuses on the safety issues arising from the interactions between the nuclear heat source and thermochemical hydrogen production cycle as well between the proximate individual processes in the cycle. As steam is utilized in most thermochemical cycles for the water splitting reaction and heat must be transferred from the nuclear source to hydrogen production plant this paper particularly analyzes and quantifies the heat hazard for the scenarios of start-up and shutdown of the hydrogen production plant. Potential safety impacts on the nuclear reactor are discussed. It is concluded that one of the main challenges of safety and risk management is efficient rejection of heat in a shutdown accident. Several options for the measures to be taken are suggested. Copper-chlorine and sulphur-iodine thermochemical cycles are taken as two representative examples for the hazard analysis. It is expected that these newly reported challenges and approaches could help build the future safety and risk management codes and standards for the infrastructure of the thermochemical hydrogen production.

The objectives of the IDEALHY project which receives funding from the European Union’s 7th Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement No. 278177 are to design a novel process that will significantly increase the efficiency of hydrogen liquefaction and be capable of delivering liquid hydrogen at a rate that is an order of magnitude greater than current plants. The liquid hydrogen could then be delivered to refueling stations in road tankers. As part of the project the safety management of the new large scale process and the transportation of liquid hydrogen by road tanker into urban areas are being considered. Effective safety management requires that the hazards are identified and well understood. This paper describes the scope of the safety work within IDEALHY and presents the output of the work completed so far. Initially a review of available experimental data on the hazards posed by releases of liquid hydrogen was undertaken which identified that generally there is a dearth of data relevant to liquid hydrogen releases. Subsequently HAZIDs have been completed for the new liquefaction process storage of liquid hydrogen and its transportation by road. This included a review of incidents relevant to these activities. The principal causes of the incidents have been analysed. Finally the remaining safety work for the IDEALHY project is outlined.

Hydrogen Infrastructures are currently being built up to support the initial commercialization of the fuel cell vehicle by multiple automakers. Three primary markets are presently coordinating a large build up of hydrogen stations: Japan; USA; and Europe to support this. Hydrogen Fuelling Station General Safety and Performance Considerations are important to establish before a wide scale infrastructure is established.

This document introduces the ISO Technical Report 19880-1 and summarizes main elements of the proposed standard. Note: this ICHS paper is based on the draft TR 19880 and is subject to change when the document is published in 2015. International Standards Organisation (ISO) Technical Committee (TC) 197 Working Group (WG) 24 has been tasked with the preparation of the ISO standard 19880-1 to define the minimum requirements considered applicable worldwide for the hydrogen and electrical safety of hydrogen stations. This report includes safety considerations for hydrogen station equipment and components control systems and operation. The following systems are covered specifically in the document as shown in Figure 1:

• H2 production / supply delivery system
• Compression
• Gaseous hydrogen buffer storage;
• Pre-cooling device;
• Gaseous hydrogen dispensers.
• Hydrogen Fuelling Vehicle Interface

The draft TR 19880-1 (and current plan for the standard) also gives guidance for the fueling validation with safety considerations relevant to the interaction between the hydrogen station and hydrogen road vehicles (during fuelling).. Through a cross-industry risk assessment carried out between OEMs Hydrogen Suppliers and existing vehicle fuelling station providers & operators (e.g. oil and industrial gas companies) the hydrogen fueling protocol SAE J2601 and associated dispenser hardware was evaluated."

The commercial deployment of hydrogen will often involve housing portable hydrogen fuel cell power units in 20-foot or 40-foot shipping containers. Due to the unique properties of hydrogen hazards identification and consequence analysis is essential to safe guard the installations and design measures to mitigate potential hazards. In the present study the explosion of a premixed hydrogen-air cloud enclosed in a 20-foot container of 20’ x 8’ x 8’.6” is investigated in detail numerically. Numerical simulations have been performed using HyFOAM a dedicated solver for vented hydrogen explosions developed in-house within the frame of the open source computational fluid dynamics (CFD) code OpenFOAM toolbox. The flame wrinkling combustion model is used for modelling turbulent deflagrations. Additional sub-models have been added to account for lean combustion properties of hydrogen-air mixtures. The predictions are validated against the recent experiments carried out by Gexcon as part of the HySEA project supported by the Fuel Cells and Hydrogen 2 Joint Undertaking (FCH 2 JU) under the Horizon 2020 Framework Programme for Research and Innovation. The effects of congestion within the containers on the generated overpressures are also investigated.

Distributed hydrogen optical fiber sensor with Brillouin scattering is an innovative solution to measure hydrogen in harsh environment as nuclear industry. Glass composition is the key point to enhance the sensing parameter of the fiber in the target application. Several optical fiber with different doping element were used for measuring hydrogen saturation. Permeability of optical plays a major role to the kinetic of hydrogen diffusion. Fluorine doped fiber increase the sorption and the desorption of hydrogen.

Hydrogen safety issue in a ventilation system of a generic nuclear containment is studied. In accidental scenarios a large amount of burnable gas mixture of hydrogen with certain amount of oxygen is released into the containment. In case of high containment pressure the combustible mixture is further ventilated into the chambers and the piping of the containment ventilation system. The burnable even potentially detonable gas mixture could pose a risk to the structures of the system once being ignited unexpectedly. Therefore the main goal of the study is to apply the computational fluid dynamics (CFD) computer code – GASFLOW to analyze the distribution of the hydrogen in the ventilation system and to find how sensitive the mixture is to detonation in different scenarios. The CFD simulations manifest that a ventilation fan with sustained power supply can extinguish the hydrogen risk effectively. However in case of station blackout with loss of power supply to the fan hydrogen/oxygen mixture could be accumulated in the ventilation system. A further study proves that steam injection could degrade the sensitivity of the hydrogen mixture significantly.

The spontaneous ignition of hydrogen released from the high pressure tank into the downstream pipes with different lengths varied from 0.3m to 2.2m has been investigated experimentally. In this study the development of shock wave was recorded by pressure sensors and photoelectric sensors were used to confirm the presence of a flame in the pipe. In addition the development of jet flame was recorded by high-speed camera and IR camera. The results show that the minimal release pressure in different tube when self-ignition of hydrogen occurred could decrease first and then increase with the increase of the aspect of pipe. And the minimum release pressure of hydrogen self-ignition was 3.87MPa. When the flame of self-ignition hydrogen spouted out of the tube Mach disk was observed. The method of CFD was adopted. The development of shock wave at the tube exit was reproduced and structures as barrel shock the reflected shock and the Mach disk are presented. Because of these special structures the flame at the nozzle is briefly extinguished and re-ignited. At the same time the complete development process of the jet flame was recorded including the formation and separation of the spherical flame. The flame structure exhibits three typical levels before the hemispherical flame separation.

The use of hydrogen as an energy carrier is a real perspective in Europe since a number of breakthroughs obtained in the last decades open the possibility to envision a deployment at the industrial scale if safety issues are duly accounted. However on this particular aspects experimental data are still lacking especially about the explosion dynamics in realistic dimensions. The purpose of this paper is to provide a set of totally new and well instrumented hydrogen - air vented explosions. Experiments were performed in a large explosion chamber within the scope of the DIMITRHY project (sponsored by the National French Agency for Research). The 4 m3 rectangular experimental chamber (2 m height 2 m width and 1 m depth) is equipped with transparent walls and is vented (0.25 and 0.5 m2 square vents).. Six pressure gauges were used to measure the overpressure evolution inside and outside the chamber. Six concentration gauges were used to control the hydrogen repartition in the vessel. The hydrogen-air cloud was seeded with micro particles of ammonium chloride to see the propagation of the flame the movement of the cloud inside and outside the chamber. The incidence of reactivity vent size ignition position and non homogenous repartition of hydrogen received a particular attention.

This paper aims to improve prediction capability of the vent sizing correlation presented in the form of functional dependence of the dimensionless deflagration overpressure on the turbulent Bradley number similar to our previous studies. The correlation is essentially upgraded based on recent advancements in understanding and modelling of combustion phenomena relevant to hydrogen-air vented deflagrations and unique large-scale tests carried out by different research groups. The focus is on hydrogen-air deflagrations in low-strength equipment and buildings when the reduced pressure is accepted to be  below 0.1 MPa. The combustion phenomena accounted for by the correlation include: turbulence generated by the flame front itself; leading point mechanism stemming from the preferential diffusion of hydrogen in air in stretched flames; growth of the fractal area of the turbulent flame surface; initial turbulence in the flammable mixture; as well as effects of enclosure aspect ratio and presence of obstacles. The correlation is validated against the widest range of experimental conditions available to date (76 experimental points). The validation covers a wide range of test conditions: different shape enclosures of volume up to 120 m3; initially quiescent and turbulent hydrogen-air mixtures; hydrogen concentration in air from 6% to 30% by volume; ignition source location at enclosure centre near and far from a vent; empty enclosures and enclosures with obstacles.