Publications

The Department of Energy the Department of Defense's Defense Logistics Agency and the Department of Transportation's Federal Transit Administration have funded learning demonstrations and early market deployments to provide insight into applications of hydrogen technologies on the road in the warehouse and as stationary power. NREL's analyses validate the technology in real-world applications reveal the status of the technology and facilitate the development of hydrogen and fuel cell technologies manufacturing and operations. This paper presents the maintenance safety and operation data of fuel cells in multiple applications with the reported incidents near misses and frequencies. NREL has analyzed records of more than 225000 kilograms of hydrogen that have been dispensed through more than 108000 hydrogen fills with an excellent safety record.

Envisioned below is an energy system named Thermal Hydrogen developed to enable economy-wide decarbonization. Thermal Hydrogen is an energy system where electric and/or heat energy is used to split water (or CO₂) for the utilization of both by-products: hydrogen as energy storage and pure oxygen as carbon abatement. Important advantages of chemical energy carriers are long term energy storage and extended range for electric vehicles. These minimize the need for the most capital intensive assets of a fully decarbonized energy economy: low carbon power plants and batteries. The pure oxygen pre-empts the gas separation process of “Carbon Capture and Sequestration” (CCS) and enables hydrocarbons to use simpler more efficient thermodynamic cycles. Thus the “externality” of water splitting pure oxygen is increasingly competitive hydrocarbons which happen to be emissions free. Methods for engineering economy-wide decarbonization are described below as well as the energy supply carrier and distribution options offered by the system.

In the accident of Fukushima Daiichi nuclear power plants hydrogen was accumulated in the reactor buildings and exploded. To prevent such explosions hydrogen venting from reactor buildings is considered. When the gas mixture is released to a reactor building through a reactor containment together with the hydrogen some amount of steam might also be released. The steam condenses if the building atmosphere is below the saturation temperature and it affects the hydrogen behaviour. In this study the condensation effect to the hydrogen venting is evaluated using CFD analyses by comparing the case where a hydrogen-nitrogen mixture is released and the case where a hydrogen-steam mixture is released.

An underground mining ventilation testing facility (VTF) was designed and constructed at the HySA facility at the North-West University South Africa. The purpose was to evaluate risks associated with different hydrogen storage technologies in a confined environment. The work included initial calculations of hydrogen movement in specific spaces and the development of simulation tools to compare these modelled results with experimental work. For this purpose hydrogen sensors that could accurately measure hydrogen concentrations during a controlled hydrogen leak at the VTF were required. Hazardous hydrogen sensors capable of measuring >4% hydrogen are not readily available commercially. Typically hydrogen sensors rated for hazardous environments are designed for safety actions (e.g. activating emergency measures when hydrogen is detected) at concentrations of 8%. (Measuring concentrations higher than this is not required for commercial use hence there is no market for such sensors.) At the VTF it is necessary to be able to measure hydrogen concentrations >4% in order to obtain information on the flammable hydrogen concentrations at specified distances and orientations around a controlled hydrogen leak. Initial experimental work was conducted at low pressures resulting in very low hydrogen concentrations. Commercial available original equipment manufacturer (OEM) hydrogen sensors were capable of measuring 0.2% hydrogen which for the low pressures and gas flows here proved sufficient to enable us to make sensible conclusions. However higher pressures and gas flows are essential in practical use hence higher concentrations of hydrogen need to be measured. A custom sensor was developed by HySA while commercial sensors (OEM) were investigated. This work reports on the testing and evaluation of several hydrogen sensors. Results of initial ventilation tests are presented.

The high variability and intermittency of wind and solar farms raise questions of how to operate electrolyzers reliably economically and sustainably using pre-dominantly or exclusively variable renewables. To address these questions we develop a comprehensive cost framework that extends to include factors such as performance degradation efficiency financing rates and indirect costs to assess the economics of 10 MW scale alkaline and proton-exchange membrane electrolyzers to generate hydrogen. Our scenario analysis explores a range of operational configurations considering (i) current and projected wholesale electricity market data from the Australian National Electricity Market (ii) existing so-lar/wind farm generation curves and (iii) electrolyzer capital costs/performance to determine costs of H2production in the near (2020–2040) and long term(2030–2050). Furthermore we analyze dedicated off-grid integrated electro-lyzer plants as an alternate operating scenario suggesting oversizing renewable nameplate capacity with respect to the electrolyzer to enhance operational capacity factors and achieving more economical electrolyzer operation.

The paper will present results of hydrogen/oxygen mixtures ignited by using electric sparks electrostatic discharges a heating element and a flame. Measurements of the lower flammability limit (LFL) was done for each ignition method. The hydrogen mixtures of different concentrations were ignited at the bottom of a combustion chamber leading to an upward propagation of the resulting flame. At some level of concentration the combustion was partial due to the limited upward propagation. The complete combustion of the whole mixture was observed at concentration limits higher than the known LFL of 4% vol. for hydrogen in air. The paper will describe the test facilities and the resulting ignition probabilities for different ignition methods.

The paper presents an overview of the main achievements of the internal project InsHyde of the HySafe NoE. The scope of InsHyde was to investigate realistic small-medium indoor hydrogen leaks and provide recommendations for the safe use/storage of indoor hydrogen systems. Additionally InsHyde served to integrate proposals from HySafe work packages and existing external research projects towards a common effort. Following a state of the art review InsHyde activities expanded into experimental and simulation work. Dispersion experiments were performed using hydrogen and helium at the INERIS gallery facility to evaluate short and long term dispersion patterns in garage like settings. A new facility (GARAGE) was built at CEA and dispersion experiments were performed there using helium to evaluate hydrogen dispersion under highly controlled conditions. In parallel combustion experiments were performed by FZK to evaluate the maximum amount of hydrogen that could be safely ignited indoors. The combustion experiments were extended later on by KI at their test site by considering the ignition of larger amounts of hydrogen in obstructed environments outdoors. An evaluation of the performance of commercial hydrogen detectors as well as inter-lab calibration work was jointly performed by JRC INERIS and BAM. Simulation work was as intensive as the experimental work with participation from most of the partners. It included pre-test simulations validation of the available CFD codes against previously performed experiments with significant CFD code inter-comparisons as well as CFD application to investigate specific realistic scenarios. Additionally an evaluation of permeation issues was performed by VOLVO CEA NCSRD and UU by combining theoretical computational and experimental approaches with the results being presented to key automotive regulations and standards groups. Finally the InsHyde project concluded with a public document providing initial guidance on the use of hydrogen in confined spaces.

The Brazilian Fuel Cell Bus Project is being developed by a consortium comprising 14 national and international partners. The project was initially supported by the GEF/UNDP and MME/FINEP Brazil. The national coordination is under responsibility of MME and EMTU/SP the São Paulo Metropolitan Urban Transport Company that also controls the bus operation and bus routes. This work reports the efforts done in order to obtain the necessary licenses to operate the first fuel cell buses for regular service in Brazil as well as the first commercial hydrogen fueling station to attend the vehicles.

The paper presents results of experimental investigations of different phlegmatizator substances and its binary compounds used for full hydrogen combustion suppression. The work was performed in experimental facilities of three different scales (small medium and large) at normal initial pressure and temperature range 20 ⎯ 120 °С. Ten individual substances and six binary compounds were tested in a small scale experiments. Three individual halogen containing substances capable of full suppression of hydrogen combustion were found in a series of small scale experiments (tube length – 1 m ID – 66 mm). The minimum concentration of the most effective substance was 11% at 20°С and 14% at 120°С in a small scale experiments. Medium scale confined and large scale unconfined experiments confirmed the possibility of full combustion suppression. The minimum concentration of the most effective binary mixture was found to be 12 % at 20°С in a large scale experiments.

Environmental pollution and energy shortage are substantial fears to the modern world's long-term sustainability. Water splitting is an essential technique for eco - friendly and sustainable energy storage as well as a pollution-free method to produce hydrogen. In this regards Metal–organic frameworks have emerged as the most competent multifunctional materials in recent times due to its large surface areas adjustable permeability easy compositional alteration and capability for usage as precursors with a wide range of morphological forms. Further MOF-derived carbon-based nanomaterials also offer significant benefits in terms of tunable morphological features and hierarchical permeability as well as ease of functionalization making them extremely effective as catalysts or catalysts supports for a wide variety of important reactions. Recent developments in carbon-based MOFs as catalysts for overall water splitting are discussed in this review. We explore how MOFs and carbon-based MOFs might well be beneficial as well as which methods should be explored for future development. We divided our review into two sections: photocatalytic and electrocatalytic water splitting and we gathered published literature on carbon-based MOFs materials for their outstanding activity offers helpful methods for catalysts design and analysis as well as difficulties This study highlights the developments in MOF derived materials as photo and electro catalysts by explaining respective approaches for their use in overall water splitting.

Sandia National Laboratories is working with stakeholders to develop scientific data for use by standards development organizations to create hydrogen codes and standards for the safe use of liquid hydrogen. Knowledge of the concentration field and flammability envelope for high-pressure hydrogen leaks is an issue of importance for the safe use of liquid hydrogen. Sandia National Laboratories is engaged in an experimental and analytical program to characterize and predict the behaviour of liquid hydrogen releases. This paper presents a model for computing hydrogen dilution distances for cold hydrogen releases. Model validation is presented for leaks of room temperature and 80 K high-pressure hydrogen gas. The model accounts for a series of transitions that occurs from a stagnate location in the tank to a point in the leak jet where the concentration of hydrogen in air at the jet centerline has dropped to 4% by volume. The leaking hydrogen is assumed to be a simple compressible substance with thermodynamic equilibrium between hydrogen vapor hydrogen liquid and air. For the multi-phase portions of the jet near the leak location the REFPROP equation of state models developed by NIST are used to account for the thermodynamics. Further downstream the jet develops into an atmospheric gas jet where the thermodynamics are described as a mixture of ideal gases (hydrogen–air mixture). Simulations are presented for dilution distances in under-expanded high-pressure leaks from the saturated vapor and saturated liquid portions of a liquid hydrogen storage tank at 10.34 barg (150 PSIG).

Faced with key obstacles such as the short driving range long charging time and limited volume allowance of battery−−powered electric light scooters in Asian cities the aim of this study is to present a passive fuel cell/battery hybrid system without DC−−DC to ensure a compact volume and low cost. A novel topology structure of the passive fuel cell/battery power system for the electric light scooter is proposed and the passive power system runs only on hydrogen. The power performance and efficiency of the passive power system are evaluated by a self−developed test bench before installation into the scooters. The results of this study reveal that the characteristics of stable power output quick response and the average efficiency are as high as 88% during the Shanghainese urban driving cycle and 89.5% during the Chinese standard driving cycle. The results pre‐ sent the possibility that this passive fuel cell/battery hybrid powertrain system without DC−DC is practical for commercial scooters.

Spontaneous ignition processes due to high pressure hydrogen releases into air are known phenomena. The sudden expansion of pressurized hydrogen into a pipe filled with ambient air can lead to a spontaneous ignition with a jet fire. This paper presents results of an experimental investigation of the visible flame propagation and pressure measurements in 4 mm extension tubes of up to 1 m length attached to a bulk vessel by a rupture disc. Transparent glass tubes for visual observation and shock wave pressure sensors are used in this study. The effect of the extension tube length on the development of a stable jet fire after a spontaneous ignition is discussed.

Computational Fluid Dynamics solvers are developed for explosion modelling and hazards analysis in Hydrogen air mixtures. The work is presented in two parts. These include firstly a numerical approach to simulate flame acceleration and deflagration to detonation transition (DDT) in hydrogen–air mixture and the second part presents comparisons between two approaches to detonation modelling. The detonation models are coded and the predictions in identical scenarios are compared. The DDT model which is presented here solves fully compressible multidimensional transient reactive Navier–Stokes equations with a chemical reaction mechanism for different stages of flame propagation and acceleration from a laminar flame to a highly turbulent flame and subsequent transition from deflagration to detonation. The model has been used to simulate flame acceleration (FA) and DDT in a 2-D symmetric rectangular channel with 0.04 m height and 1 m length which is filled with obstacles. Comparison has been made between the predictions using a 21-step detailed chemistry as well as a single step reaction mechanism. The effect of initial temperature on the run-up distances to DDT has also been investigated. Comparative study has also been carried out for two detonation solvers. one detonation solver is developed based on the solution of the reactive Euler equations while the other solver has a simpler approach based on Chapman–Jouguet model and the programmed CJ burn method. Comparison has shown that the relatively simple CJ burn approach is unable to capture some very important features of detonation when there are obstacles present in the cloud.

In order to improve risk analyses and influence the design of the future H2 systems an experimental study on “real” leaks qualification and quantification was performed. In H2 energy applications fittings appeared as a significant leakage potential and subsequently explosion and flame hazards. Thus as a part of the “Horizon Hydrogène Energie” French program four kinds of commercial fittings usually employed on H2 systems were tested thanks to a new high pressure test bench – designed setup and operated by INERIS – allowing experiments to be led for H2 pressures until 700 bar. The fittings underwent defined stresses representative of H2 systems lifetime and beyond. The associated leaks – when existing – are characterized in terms of flow rate.

This experimental work analyzes the hydrogen embrittlement mechanism in quenched and tempered low-alloyed steels. Experimental tests were performed to study hydrogen diffusion under applied cyclic loading. The permeation curves were fitted by considering literature models in order to evaluate the role of trapping—both reversible and irreversible—on the diffusion mechanism. Under loading conditions a marked shift to the right of the permeation curves was noticed mainly at values exceeding the tensile yield stress. In the presence of a relevant plastic strain the curve changes due to the presence of irreversible traps which efficiently subtract diffusible atomic hydrogen. A significant reduction in the apparent diffusion coefficient and a considerable increase in the number of traps were noticed as the maximum load exceeded the yield strength. Cyclic loading at a tensile stress slightly higher than the yield strength of the material increases the hydrogen entrapment phenomena. The tensile stress causes a marked and instant reduction in the concentration of mobile hydrogen within the metal lattice from 55% of the yield strength and it increases significantly in the plastic field.

Hydrogen production by steam reforming of ethylene glycol (EG) at 300 °C was investigated over SiO2 and CeO2 supported Pt–Ni bimetallic catalysts prepared by incipient wetness impregnation methods. It was observed that impregnation sequence of Pt and Ni can affect the performance of catalysts apparently. Catalyst with Pt first and then Ni addition showed higher EG conversion and H2 yield owing to the Ni enrichment on the surface and the proper interaction between Pt and Ni. It was observed that although SiO2 supported catalysts exhibited better activity and H2 selectivity CeO2 supported ones had better stability. This is attributed to the less coke formation on CeO2. Increasing Pt/Ni ratio enhanced the reaction activity and Pt3–Ni7 catalysts with 3 wt% Pt and 7 wt% Ni showed the highest activity and stability. Ni surficial enrichment facilitated the C—C bond rupture and water gas shift reactions; and Pt addition inhibited methanation reaction. Electron transfer and hydrogen spillover from Pt to Ni suppressed carbon deposition. These combined effects lead to the excellent performance of Pt3–Ni7 supported catalysts.

Development of regulations codes and standards on hydrogen safety is a primary ingredient in overcoming barriers to widespread use of hydrogen energy. Key points of the new China National Standard Essential safety requirements for hydrogen systems metal hydrogen compatibility and risk control of flammability and explosion are discussed. Features  of the new standard such as safety requirements for slush hydrogen systems and solid state hydrogen storage systems and introductions for hydrogen production by renewable energy are analyzed in this paper.

Hydrogen has been used as an industrial chemical for more than 100 years. Today hydrogen is used to manufacture ammonia and hence fertilizers as well as methanol and hydrogen peroxide both vital feedstocks for a wide variety of different chemical products. Furthermore in oil refineries hydrogen is used for the processing of intermediate products as well as to increase the hydrogen contents of the final products that are used propel the vehicles. However hydrogen has recently achieved new attention for its capabilities in reducing carbon emissions to the atmosphere. Producing hydrogen via low or totally carbon-free ways and using this “good” low-carbon hydrogen to replace hydrogen with a larger carbon footprint we can reduce carbon emissions. Furthermore using renewable electricity and captured carbon we can synthesise many such chemical products that are currently produced from fossil raw materials. This “Power-to-X” (P2X) is often seen as the eventual incarnation of the hydrogen economy. In addition the progress in technology both in hydrogen fuel cells and in polymer electrolyte electrolysers alike has increased their efficiencies.<br/>Furthermore production costs of renewable electricity by wind or solar power have lowered significantly. Thus cost of “good” hydrogen has also decreased markedly and production volumes are expected to increase rapidly. For these reasons many countries have raised interests in “good” hydrogen and have created roadmaps and strategies for their involvement in hydrogen. Hydrogen plays a key role also in combating climate change and reaching Finland's national goal of carbon neutrality by 2035. In recent years many clean hydrogen and P2X production methods have developed significantly and become commercially viable.<br/>This report was produced by a team of VTT experts on hydrogen and hydrogen-related technologies. The focus is in an outlook for low-carbon H2 production H2 utilization for green chemicals and fuels as well as storage transport and end-use especially during the next 10 years in Finland in connection to renewed EU regulations. This roadmap is expected to serve as the knowledge-base for further work such as shaping the hydrogen policy for Finland and determining the role of hydrogen in the national energy and climate policy.

Green hydrogen supply chain includes supply sources production and distribution of hydrogen produced from renewable energy sources (RES). It is a promising scientific and application area as it is related to the problem of instability of power grids supplied with RES. The article presents the conceptual assumptions of the research on the design of a functional multi-criteria model of the stabilization model architecture of energy distribution networks based on a hydrogen energy buffer taking into account the applicable use of hydrogen. The aim of the research was to identify the variables contributing to the stabilization of the operation of distribution networks. The method used to obtain this result was a systematic review of the literature using the technique of in-depth analysis of full-text articles and expert consultations. The concept of a functional model was described as a matrix in two dimensions in which the identified variables were embedded. The first dimension covers the phases of the supply chain: procurement and production along with storage and distribution. The second dimension divides the separate factors into technical economic and logistic. The research was conducted in the context of system optimization from the point of view of the operator of the energy distribution system. As a result of the research several benefits resulting from stabilization using a hydrogen buffer were identified. Furthermore the model may be used in designing solutions stabilizing the operation of power grids in which there are surpluses of electricity produced from RES. Due to the applied multidimensional approach the developed model is recommended for use as it enables the design of solutions in a systemic manner. Due to the growing level of energy obtained from renewable energy sources the issue of stabilizing the energy network is becoming increasingly important for energy network distributors.

Efficient storage of hydrogen is crucial for the success of hydrogen energy markets (early markets as well as transportation market). Hydrogen can be stored either as a compressed gas a refrigerated liquefied gas a cryo-compressed gas or in hydrides. This paper gives an overview of hydrogen storage technologies and details the specific issues and constraints related to the materials behaviour in hydrogen and conditions representative of hydrogen energy uses. It is indeed essential for the development of applications requiring long-term performance to have good understanding of long-term behaviour of the materials of the storage device and its components under operational loads.

Hydrogen is one of the promising energy sources in the future because it has the advantages of clean combustion products high efficiency and renewable energy. However hydrogen has the characteristics of low ignition energy wide flammable range (4% -75%) and fast burning flame speed which can cause explosion hazards. Typically the accidental release of hydrogen into confined or semi confined enclosures can often lead to a flammable hydrogen-air mixture with concentration gradients and possible flame acceleration and deflagration-to-detonation transition (DDT). The present study aims to test the capability of our in-house density-based solver ExplosionEngFoam for flame acceleration (FA) and deflagration-to-detonation transition (DDT) in homogenous/inhomogeneous hydrogen-air mixtures. The solver is based on the open source computational fluid dynamics (CFD) platform OpenFOAM and uses the modified Weller et al.’s combustion model taking into account LD and RT instabilities turbulence and non-unity Lewis number etc. Numerical simulations were conducted for both homogeneous and inhomogeneous mixtures in a long enclosed channel with 5.4 m in length and 0.06 m in height. The predictions demonstrate good quantitative agreement with the experimental measurements in flame tip position speed and pressure profiles by Boeck et al. The flow characteristics such as flame fine structure wave evolution etc. were also discussed.

To facilitate the transition to the hydrogen economy the EU project NATURALHY is studying the potential for the existing natural gas pipeline networks to transport hydrogen together with natural gas to end-users. Hydrogen may then be extracted for hydrogen fuel-cell applications or the mixture used directly by consumers in existing gas-fired equipment with the benefit of lower carbon emissions. The existing gas pipeline networks are designed constructed and operated to safely transport natural gas mostly methane. However hydrogen has significantly different properties that may adversely affect both the integrity of the network and thereby increase the likelihood of an accidental leak and the consequences if the leak finds a source of ignition. Consequently a major part of the NATURALHY project is focused on assessing how much hydrogen could be introduced into the network without adversely impacting on the safety of the network and the risk to the public. Hydrogen is more reactive than natural gas so the severity of an explosion following an accidental leak may be increased. This paper describes field-scale experiments conducted to measure the overpressures generated by ignition of methane/hydrogen/air mixtures in a congested but unconfined region. Such regions may be found in the gas handling and metering stations of the pipeline networks. The 3 m x 3 m x 2 m high congested region studied contained layers of pipes. The composition of the methane/hydrogen mixture used was varied from 0% hydrogen to 100% hydrogen. On the basis of the experiments performed the maximum overpressures generated by methane/hydrogen mixtures with 25% (by volume) or less hydrogen content are not likely to be much more than those generated by methane alone. Greater percentages of hydrogen did significantly increase the explosion overpressure.

Considering the transition towards the hydrogen economy dependent on hydrogen penetration scenario the cost of a new hydrogen pipeline infrastructure in Europe may amount to several thousands of billions of EURO’s. Therefore the examination of the potential contribution of the existing natural gas assets is a practical and logical first step. As the physical and chemical properties of hydrogen differ significantly from those of natural gas it is not at all possible to simply exchange natural gas by hydrogen in the existing infrastructure. In this paper first a brief overview will be given of the NATURALHY-project. Further the focus will be on the impact of added hydrogen on the performance of existing natural gas domestic end user appliances which is related to the operation of the natural gas grid connecting the different types of appliance. The application of the fundamental insights and carefully designed experiments comparing the behaviour of gases using justified reference conditions have been shown to offer essential progress. The Wobbe index limits of the natural gas distributed pose a first limiting factor upon the maximum allowable hydrogen concentration. Constant-Wobbe index and decreasing-Wobbe index options of H2 admixture have been studied. Considering the appliance light back H2 limiting factor for domestic appliances fuel-rich appliances are the critical ones. Also taking into account stationary gas engines gas turbines industrial applications and natural gas grid management it is not yet justified to present statements on what level of hydrogen concentration could be safely allowed in which specific natural gas distribution region. But more clarity has been obtained on combustion safety aspects of existing domestic appliances on the connection with Wobbe distribution conditions and on the bottlenecks still to be handled.

The production of hydrogen from renewable sources is essential to develop the future hydrogen economy. Biomass is an abundant clean and renewable energy source and it can be important in the production of hydrogen. The Valencian Community due to its great agricultural and forestry activities generates an important quantity of biomass residues that can be used for energy generation approximately 778 kt of wet biomass residues per year. This great quantity of biomass can be transformed into a hydrogen-rich gas by different thermochemical conversion processes. In this article the potential of production of hydrogen-rich gas is analyzed considering several factors affecting the conversion yield of these processes. As a result of this analysis it could be possible to produce 1271 MNm3 of H₂ per year considering the total biomass residues of the community and selecting the gasification processes.