United States
An Overview of Hydrogen Safety Sensors and Requirements
Sep 2009
Publication
There exists an international commitment to increase the utilization of hydrogen as a clean and renewable alternative to carbon-based fuels. The availability of hydrogen safety sensors is critical to assure the safe deployment of hydrogen systems. Already the use of hydrogen safety sensors is required for the indoor fueling of fuel cell powered forklifts (e.g. NFPA 52 Vehicular Fuel Systems Code [1]). Additional Codes and Standards specific to hydrogen detectors are being developed [2 3] which when adopted will impose mandatory analytical performance metrics. There are a large number of commercially available hydrogen safety sensors. Because end-users have a broad range of sensor options for their specific applications the final selection of an appropriate sensor technology can be complicated. Facility engineers and other end-users are expected to select the optimal sensor technology choice. However some sensor technologies may not be a good fit for a given application. Informed decisions require an understanding of the general analytical performance specifications that can be expected by a given sensor technology. Although there are a large number of commercial sensors most can be classified into relatively few specific sensor types (e.g. electrochemical metal oxide catalytic bead and others). Performance metrics of commercial sensors produced on a specific platform may vary between manufacturers but to a significant degree a specific platform has characteristic analytical trends advantages and limitations. Knowledge of these trends facilitates the selection of the optimal technology for a specific application (i.e. indoor vs. outdoor environments). An understanding of the various sensor options and their general analytical performance specifications would be invaluable in guiding the selection of the most appropriate technology for the designated application.
Vented Explosion Overpressures From Combustion of Hydrogen and Hydrocarbon Mixtures
Sep 2009
Publication
Experimental data obtained for hydrogen mixtures in a room-size enclosure are presented and compared with data for propane and methane mixtures. This set of data was also used to develop a three-dimensional gas dynamic model for the simulation of gaseous combustion in vented enclosures. The experiments were performed in a 64 m3 chamber with dimensions of 4.6 × 4.6 × 3.0 m and a vent opening on one side and vent areas of either 2.7 or 5.4 m2 were used. Tests were performed for three ignition locations at the wall opposite the vent at the center of the chamber or at the center of the wall containing the vent. Hydrogen–air mixtures with concentrations close 18% vol. were compared with stoichiometric propane–air and methane–air mixtures. Pressure data as function of time and flame time-of-arrival data were obtained both inside and outside the chamber near the vent. Modelling was based on a Large Eddy Simulation (LES) solver created using the OpenFOAM CFD toolbox using sub-grid turbulence and flame wrinkling models. A comparison of these simulations with experimental data is discussed.
From Research Results to Published Codes And Standards - Establishing Code Requirements For NFPA 55 Bulk Hydrogen Systems Separation Distances
Sep 2009
Publication
Performing research in the interest of providing relevant safety requirements is a valuable and essential endeavor but translating research results into enforceable requirements adopted into codes and standards a process sometimes referred to as codification can be a separate and challenging task. This paper discusses the process utilized to successfully translate research results related to bulk gaseous hydrogen storage separation (or stand-off) distances into code requirements in NFPA 55:Storage Use and Handling of Compressed Gases and Cryogenic Fluids in Portable and StationaryContainers Cylinders and Tanks and NFPA 2: Hydrogen Technologies. The process utilized can besummarized as follows: First the technical committees for the documents to be revised were engaged to confirm that the codification process was endorsed by the committee. Then a sub-committee referred to as a task group was formed. A chair must be elected or appointed. The chair should be a generalist with code enforcement or application experience. The task group was populated with several voting members of each technical committee. By having voting members as part of the task group the group becomes empowered and uniquely different from any other code proposal generating body. The task group was also populated with technical experts as needed but primarily the experts needed are the researchers involved. Once properly populated and empowered the task group must actively engage its members. The researchers must educate the code makers on the methods and limitations of their work and the code makers must take the research results and fill the gaps as needed to build consensus and create enforceable code language and generate a code change proposal that will be accepted. While this process seems simple there are pitfalls along the way that can impede or nullify the desired end result – changes to codes and standards. A few of these pitfalls include: wrong task group membership task group not empowered task group not supported in-person meetings not possible consensus not achieved. This paper focuses on the process used and how pitfalls can be avoided for future efforts.
Novel Wide-area Hydrogen Sensing Technology
Sep 2007
Publication
Element One Inc. is developing novel indicators for hydrogen gas for applications as a complement to conventional electronic hydrogen sensors or as a low-cost alternative in situations where an electronic signal is not needed. The indicator consists of a thin film coating or a pigment of a transition metal oxide such as tungsten oxide or molybdenum oxide with a catalyst such as platinum or palladium. The oxide is partially reduced in the presence of hydrogen in concentrations as low as 300 parts per million and changes from transparent to a dark colour. The colour change is fast and easily seen from a distance. In air the colour change reverses quickly when the source of hydrogen gas is removed in the case of tungsten oxide or is nearly irreversible in the case of molybdenum oxide. A number of possible implementations have been successfully demonstrated in the laboratory including hydrogen indicating paints tape cautionary decals and coatings for hydrogen storage tanks. These and other implementations may find use in vehicles stationary appliances piping refuelling stations and in closed spaces such as maintenance and residential garages for hydrogen-fuelled vehicles. The partially reduced transition metal oxide becomes semi conductive and increases its electrical conductivity by several orders of magnitude when exposed to hydrogen. The integration of this electrical resistance sensor with an RFID tag may extend the ability of these sensors to record and transmit a history of the presence or absence of leaked hydrogen over long distances. Over long periods of exposure to the atmosphere the indicator’s response may slow due to catalyst degradation. Our current emphasis is on controlling this degradation. The kinetics of the visual indicators is being investigated along with their durability in collaboration with the NASA Kennedy Space Center.
Development of Standards for Evaluating Materials Compatibility with High-pressure Gaseous Hydrogen
Sep 2013
Publication
The Hydrogen Safety Codes and Standards program element of the US Department of Energy's Fuel Cell Technologies Office provides coordination and technical data for the development of domestic and international codes and standards related to hydrogen technologies. The materials compatibility program task at Sandia National Laboratories (Livermore CA) is focused on developing the technical basis for qualifying materials for hydrogen service i.e. accommodating hydrogen embrittlement. This presentation summarizes code development activities for qualifying materials for hydrogen service with emphasis on the scientific basis for the testing methodologies including fracture mechanics based measurements (fracture threshold and fatigue crack growth) total fatigue life measurements and full- scale pressure vessel testing.
Simulation of Small-Scale Releases from Liquid Hydrogen Storage Systems
Sep 2009
Publication
Knowledge of the concentration field and flammability envelope from small-scale leaks is important for the safe use of hydrogen. These small-scale leaks may occur from leaky fittings or o-ring seals on liquid hydrogen-based systems. The present study focuses on steady-state leaks with large amounts of pressure drop along the leak path such that hydrogen enters the atmosphere at near atmospheric pressure (i.e. Very low Mach number). A three-stage buoyant turbulent entrainment model is developed to predict the properties (trajectory hydrogen concentration and temperature) of a jet emanating from the leak. Atmospheric hydrogen properties (temperature and quality) at the leak plane depend on the storage pressure and whether the leak occurs from the saturated vapor space or saturated liquid space. In the first stage of the entrainment model ambient temperature air (295 K) mixes with the leaking hydrogen (20–30 K) over a short distance creating an ideal gas mixture at low temperature (∼65 K). During this process states of hydrogen and air are determined from equilibrium thermodynamics using models developed by NIST. In the second stage of the model (also relatively short in distance) the radial distribution of hydrogen concentration and velocity in the jet develops into a Gaussian profile characteristic of free jets. The third and by far the longest stage is the part of the jet trajectory where flow is fully developed. Results show that flammability envelopes for cold hydrogen jets are generally larger than those of ambient temperature jets. While trajectories for ambient temperature jets depend solely on the leak densimetric Froude number results from the present study show that cold jet trajectories depend on the Froude number and the initial jet density ratio. Furthermore the flammability envelope is influenced by the hydrogen concentration in the jet at the beginning of fully developed flow.
Environmental Reactivity of Solid State Hydride Materials
Sep 2009
Publication
In searching for high gravimetric and volumetric density hydrogen storage systems it is inevitable that higher energy density materials will be used. In order to make safe and commercially acceptable condensed phase hydrogen storage systems it is important to understand quantitatively the hazards involved in using and handling these materials and to develop appropriate mitigation strategies to handle potential material exposure events. A crucial aspect of the development of risk identification and mitigation strategies is the development of rigorous environmental reactivity testing standards and procedures. This will allow for the identification of potential hazards and implementation of risk mitigation strategies. Modified testing procedures for shipping air and/or water sensitive materials as codified by the United Nations have been used to evaluate two potential hydrogen storage materials 2LiBH4·MgH2 and NH3BH3. The modified U.N. procedures include identification of self-reactive substances pyrophoric substances and gas-emitting substances with water contact. The results of these tests for air and water contact sensitivity will be compared to the pure material components where appropriate (e.g. LiBH4 and MgH2). The water contact tests are divided into two scenarios dependent on the hydride to water mole ratio and heat transport characteristics. Air contact tests were run to determine whether a substance will spontaneously react with air in a packed or dispersed form. Relative to 2LiBH4·MgH2 the chemical hydride NH3BH3 was observed to be less environmentally reactive.
Hydrogen Compatibility of Austenitic Stainless Steel Tubing and Orbital Tube Welds
Sep 2013
Publication
Refueling infrastructure for use in gaseous hydrogen powered vehicles requires extensive manifolding for delivering the hydrogen from the stationary fuel storage at the refueling station to the vehicle as well as from the mobile storage on the vehicle to the fuel cell or combustion engine. Manifolds for gas handling often use welded construction (as opposed to compression fittings) to minimize gas leaks. Therefore it is important to understand the effects of hydrogen on tubing and tubing welds. This paper provides a brief overview of on-going studies on the effects of hydrogen precharging on the tensile properties of austenitic stainless tubing and orbital tube welds of several austenitic stainless steels.
Hourly Modelling of Thermal Hydrogen Electricity Markets
Jul 2020
Publication
The hourly operation of Thermal Hydrogen electricity markets is modelled. The economic values for all applicable chemical commodities are quantified (syngas ammonia methanol and oxygen) and an hourly electricity model is constructed to mimic the dispatch of key technologies: bi-directional power plants dual-fuel heating systems and plug-in fuel-cell hybrid electric vehicles. The operation of key technologies determines hourly electricity prices and an optimization model adjusts the capacity to minimize electricity prices yet allow all generators to recover costs. We examine 12 cost scenarios for renewables nuclear and natural gas; the results demonstrate emissionsfree ‘energy-only’ electricity markets whose supply is largely dominated by renewables. The economic outcome is made possible in part by seizing the full supply-chain value from electrolysis (both hydrogen and oxygen) which allows an increased willingness to pay for (renewable) electricity. The wholesale electricity prices average $25–$45/ MWh or just slightly higher than the assumed levelized cost of renewable energy. This implies very competitive electricity prices particularly given the lack of need for ‘scarcity’ pricing capacity markets dedicated electricity storage or underutilized electric transmission and distribution capacity.
Hydrogen Strategy - Enabling a Low-Carbon Economy
Jul 2020
Publication
This document summarizes current hydrogen technologies and communicates the U.S. Department of Energy (DOE) Office of Fossil Energy's (FE's) strategic plan to accelerate research development and deploymnet of hydrogen technologies in the United States. It also describes ongoing FE hydrogen-related research and development (R&D). Hydrogen from fossil fuels is a versatile energy carrier and can play an important role in the transition to a low-carbon economy.
Carbon Negative Transportation Fuels - A Techno-Economic-Environmental Analysis of Biomass Pathways for Transportation
Feb 2022
Publication
Global warming and fossil fuel depletion have necessitated alternative sources of energy. Biomass is a promising fuel source because it is renewable and can be carbon negative even without carbon capture and storage. This study considers biomass as a clean renewable source for transportation fuels. An Aspen Plus process simulation model was built of a biomass gasification biorefinery with Fischer-Tropsch (FT) synthesis of liquid fuels. A GaBi life cycle assessment model was also built to determine the environmental impacts using a cradle-to-grave approach. Three different product pathways were considered: Fischer-Tropsch synthetic diesel hydrogen and electricity. An offgas autothermal reformer with a recycle loop was used to increase FT product yield. Different configurations and combinations of biorefinery products are considered. The thermal efficiency and cost of production of the FT liquid fuels are analyzed using the Aspen Plus process model. The greenhouse gas emissions profitability and mileage per kg biomass were compared. The mileage traveled per kilogram biomass was calculated using modern (2019-2021) diesel electric and hydrogen fuel cell vehicles. The overall thermal efficiency was found to be between 20-41% for FT fuels production between 58-61% for hydrogen production and around 25-26% for electricity production for this biorefinery. The lowest production costs were found to be $3.171/gal of FT diesel ($24.304/GJ) $1.860/kg of H2 ($15.779/GJ) and 13.332¢/kWh for electricity ($37.034/GJ). All configurations except one had net negative carbon emissions over the life cycle of the biomass. This is because carbon is absorbed in the trees initially and some of the carbon is sequestered in ash and unconverted char from the gasification process furthermore co-producing electricity while making transportation fuel offsets even more carbon emissions. Compared to current market rates for diesel hydrogen and electricity the most profitable biorefinery product is shown to be hydrogen while also having net negative carbon emissions. FT diesel can also be profitable but with a slimmer profit margin (not considering government credits) and still having net negative carbon emissions. However our biorefinery could not compete with current commercial electricity prices in the US. As oil hydrogen and electricity prices continue to change the economics of the biorefinery and the choice product will change as well. For our current biorefinery model hydrogen seems to be the most promising product choice for profit while staying carbon negative while FT diesel is the best choice for sequestering the most carbon and still being profitable. All code and data are given.
Updated Jet Flame Radiation Modelling with Corrections for Buoyancy and Wind
Sep 2013
Publication
Radiative heat fluxes from small to medium-scale hydrogen jet flames (<10 m) compare favorably to theoretical predictions provided the product species thermal emittance and optical flame thickness are corrected for. However recent heat flux measurements from two large-scale horizontally orientated hydrogen flames (17.4 and 45.9 m respectively) revealed that current methods underpredicted the flame radiant fraction by 40% or more. Newly developed weighted source flame radiation models have demonstrated substantial improvement in the heat flux predictions particularly in the near-field and allow for a sensible way to correct potential ground surface reflective irradiance. These updated methods are still constrained by the fact that the flame is assumed to have a linear trajectory despite buoyancy effects that can result in significant flame deformation. The current paper discusses a method to predict flame centerline trajectories via a one-dimensional flame integral model which enables optimized placement of source emitters for weighted multi-source heat flux prediction methods. Flame shape prediction from choked releases was evaluated against flame envelope imaging and found to depend heavily on the notional nozzle model formulation used to compute the density weighted effective nozzle diameter. Nonetheless substantial improvement in the prediction of downstream radiative heat flux values occurred when emitter placement was corrected by the flame integral model regardless of the notional nozzle model formulation used.
Experimental Study of Hydrogen Release Accidents in a Vehicle Garage
Sep 2009
Publication
Storing a hydrogen fuel-cell vehicle in a garage poses a potential safety hazard because of the accidents that could arise from a hydrogen leak. A series of tests examined the risk involved with hydrogen releases and deflagrations in a structure built to simulate a one-car garage. The experiments involved igniting hydrogen gas that was released inside the structure and studying the effects of the deflagrations. The “garage” measured 2.72 m high 3.64 m wide and 6.10 m long internally and was constructed from steel using a reinforced design capable of withstanding a detonation. The front face of the garage was covered with a thin transparent plastic film. Experiments were performed to investigate extended-duration (20–40 min) hydrogen leaks. The effect that the presence of a vehicle in the garage has on the deflagration was also studied. The experiments examined the effectiveness of different ventilation techniques at reducing the hydrogen concentration in the enclosure. Ventilation techniques included natural upper and lower openings and mechanical ventilation systems. A system of evacuated sampling bottles was used to measure hydrogen concentration throughout the garage prior to ignition and at various times during the release. All experiments were documented with standard and infrared (IR) video. Flame front propagation was monitored with thermocouples. Pressures within the garage were measured by four pressure transducers mounted on the inside walls of the garage. Six free-field pressure transducers were used to measure the pressures outside the garage.
Analysis of Composite Hydrogen Storage Cylinders under Transient Thermal Loads
Sep 2007
Publication
In order to ensure safe operation of hydrogen storage cylinders under adverse conditions one should be able to predict the extremities under which these cylinders are capable of operating without failing catastrophically. It is therefore necessary to develop a comprehensive model which can predict the behavior and failure of composite storage cylinders when subjected to various types of loading conditions and operating environments. In the present work a finite element model has been developed to analyze composite hydrogen storage cylinders subjected to transient localized thermal loads and internal pressure. The composite cylinder consists of an aluminium liner that serves as a hydrogen gas permeation barrier. A filament-wound carbon/epoxy composite laminate placed over the liner provides the desired load bearing capacity. A glass/epoxy layer or other material is placed over the carbon/epoxy laminate to provide damage resistance for the carbon/epoxy laminates. A doubly curved composite shell element accounting for transverse shear deformation and geometric nonlinearity is used. A temperature dependent material model has been developed and implemented in ABAQUS using user subroutine. A failure model based on Hashin's failure theory is used to predict the various types of failure in the cylinder. A progressive damage model has also been implemented to account for reduction in modulus due to failure. A sublaminate model has been developed to save computational time and reduce the complications in the analysis. A numerical study is conducted to analyze a typical hydrogen storage cylinder and possible failure trends due to localized thermal loading and internal pressure is presented.
Deflagration Safety Study of Mixtures of Hydrogen and Natural Gas in a Semi-open Space
Sep 2007
Publication
In the transition to a hydrogen economy it is likely that hydrogen will be used or stored in close proximity to other flammable fuels and gases. Accidents can occur that result in the release of two or more fuels such as hydrogen and natural gas that can mix and form a hazard. A series of five medium-scale semi-open-space deflagration experiments have been conducted with hydrogen natural gas and air mixtures. The natural gas consisted of 90% methane 6% ethane 3% propane and 1% butane by volume. Mixtures of hydrogen and natural gas were created with the hydrogen mole fraction in the fuel varying from 1.000 to 0.897 and the natural gas mole fraction varying from 0.000 to 0.103. The hydrogen and natural gas mixture was then released inside a 5.27-m³ thin plastic tent. The stoichiometric fuel-air mixtures were ignited with a 40-J spark located at the bottom center of the tent. Overpressure and impulse data were collected using pressure transducers located within the mixture volume and in the free field. Flame front time-of-arrival was measured using fast response thermocouples and infrared video. Flame speeds relative to a fixed observer were measured between 36.2 m/s and 19.7 m/s. Average peak overpressures were measured between 2.0 kPa and 0.3 kPa. The addition of natural gas inhibited the combustion when the hydrogen mole fraction was less than or equal to 0.949. For these mixtures there was a significant decrease in overpressures. When the hydrogen mole fraction in the fuel was between 0.999 and 0.990 the overpressures were slightly higher than for the case of hydrogen alone. This could be due to experimental scatter or there may be a slight enhancement of the combustion when a very small amount of natural gas was present. From a safety standpoint variation in overpressure was small and should have little effect on safety considerations.
Recent Progress and Approaches on Transition Metal Chalcogenides for Hydrogen Production
Dec 2021
Publication
Development of efficient and affordable photocatalysts is of great significance for energy production and environmental sustainability. Transition metal chalcogenides (TMCs) with particle sizes in the 1–100 nm have been used for various applications such as photocatalysis photovoltaic and energy storage due to their quantum confinement effect optoelectronic behavior and their stability. In particular TMCs and their heterostructures have great potential as an emerging inexpensive and sustainable alternative to metal-based catalysts for hydrogen evolution. Herein the methods used for the fabrication of TMCs characterization techniques employed and the different methods of solar hydrogen production by using different TMCs as photocatalyst are reviewed. This review provides a summary of TMC photocatalysts for hydrogen production.
PRD Hydrogen Release and Dispersion, a Comparison of CFD Results Obtained from Using Ideal and Real Gas Law Properties.
Sep 2005
Publication
In this paper CFD techniques were applied to the simulations of hydrogen release from a 400-bar tank to ambient through a Pressure Relieve Device (PRD) 6 mm (¼”) opening. The numerical simulations using the TOPAZ software developed by Sandia National Laboratory addressed the changes of pressure density and flow rate variations at the leak orifice during release while the PHOENICS software package predicted extents of various hydrogen concentration envelopes as well as the velocities of gas mixture for the dispersion in the domain. The Abel-Noble equation of state (AN-EOS) was incorporated into the CFD model implemented through the TOPAZ and PHOENICS software to accurately predict the real gas properties for hydrogen release and dispersion under high pressures. The numerical results were compared with those obtained from using the ideal gas law and it was found that the ideal gas law overestimates the hydrogen mass release rates by up to 35% during the first 25 seconds of release. Based on the findings the authors recommend that a real gas equation of state be used for CFD predictions of high-pressure PRD releases.
Hydrogen Embrittlement of Medium Mn Steels
Feb 2021
Publication
Recent research efforts to develop advanced–/ultrahigh–strength medium-Mn steels have led to the development of a variety of alloying concepts thermo-mechanical processing routes and microstructural variants for these steel grades. However certain grades of advanced–/ultrahigh–strength steels (A/UHSS) are known to be highly susceptible to hydrogen embrittlement due to their high strength levels. Hydrogen embrittlement characteristics of medium–Mn steels are less understood compared to other classes of A/UHSS such as high Mn twinning–induced plasticity steel because of the relatively short history of the development of this steel class and the complex nature of multiphase fine-grained microstructures that are present in medium–Mn steels. The motivation of this paper is to review the current understanding of the hydrogen embrittlement characteristics of medium or intermediate Mn (4 to 15 wt pct) multiphase steels and to address various alloying and processing strategies that are available to enhance the hydrogen-resistance of these steel grades.
Simulations of Hydrogen Releases from a Storage Tanks- Dispersion and Consequences of Ignition
Sep 2005
Publication
We present results from hydrogen dispersion simulations from a pressurized reservoir at constant flow rate in the presence and absence of a wall. The dispersion simulations are performed using a commercial finite volume solver. Validation of the approach is discussed. Constant concentration envelopes corresponding to the 2% 4% and 15% hydrogen concentration in air are calculated for a subcritical vertical jet and for an equivalent subcritical horizontal jet from a high pressure reservoir. The consequences of ignition and the resulting overpressure are calculated for subcritical horizontal and vertical hydrogen jets and in the latter case compared to available experimental data.
Everything About Hydrogen Podcast: Is This the End of the Diesel Train?
Jan 2020
Publication
For this show the team are taking a dive into the world of hydrogen trains and who better to speak to this space than Mike Muldoon Head of Business Development and Marketing for Alstom UK&I. Alstom have been the pioneers of hydrogen powered rail and in addition to two operating trains in Germany have secured over Eur500 million of orders for hydrogen trains. On the show we talk to Mike about why Alstom see hydrogen as a key part of the evolution of the rail industry towards zero emissions and why hydrogen today is such a compelling proposition for operators and investors.
The podcast can be found on their website
The podcast can be found on their website
National Training Facility for Hydrogen Safety. Five year plan for HAMMER
Sep 2005
Publication
A suitably trained emergency response force is an essential component for safe implementation of any type of fuel infrastructure. Because of the relative newness of hydrogen as a fuel however appropriate emergency response procedures are not yet well understood by responder workforces across the United States and around the world. A significant near-term training effort is needed to ensure that the future hydrogen infrastructure can be developed and operated with acceptable incident risk. Efforts are presently underway at the HAMMER site in Washington State to develop curricula related to hydrogen properties and behavior identification of problems (e.g. incorrect equipment installation) and appropriate response and other relevant information intended for classroom instruction. In addition a number of hands-on training props are planned for realistic simulation of hydrogen incidents in order to convey proper response procedures in high-pressure cryogenic high leakage or other high-risk accident situations. Surveys of emergency responders fire marshals regulatory authorities manufacturers and others are being undertaken to ensure that the capabilities developed and offered at HAMMER will meet the acknowledged need. This paper describes the training curricula and props anticipated at HAMMER and is intended to provide useful information to others planning similar training programs.
Large-Scale Hydrogen Deflagrations and Detonations
Sep 2005
Publication
Large-scale deflagration and detonation experiments of hydrogen and air mixtures provide fundamental data needed to address accident scenarios and to help in the evaluation and validation of numerical models. Several different experiments of this type were performed. Measurements included flame front time of arrival (TOA) using ionization probes blast pressure heat flux high-speed video standard video and infrared video. The large-scale open-space tests used a hemispherical 300-m3 facility that confined the mixture within a thin plastic tent that was cut prior to initiating a deflagration. Initial homogeneous hydrogen concentrations varied from 15% to 30%. An array of large cylindrical obstacles was placed within the mixture for some experiments to explore turbulent enhancement of the combustion. All tests were ignited at the bottom center of the facility using either a spark or in one case a small quantity of high explosive to generate a detonation. Spark-initiated deflagration tests were performed within the tunnel using homogeneous hydrogen mixtures. Several experiments were performed in which 0.1 kg and 2.2 kg of hydrogen were released into the tunnel with and without ventilation. For some tunnel tests obstacles representing vehicles were used to investigate turbulent enhancement. A test was performed to investigate any enhancement of the deflagration due to partial confinement produced by a narrow gap between aluminium plates. The attenuation of a blast wave was investigated using a 4-m-tall protective blast wall. Finally a large-scale hydrogen jet experiment was performed in which 27 kg of hydrogen was released vertically into the open atmosphere in a period of about 30 seconds. The hydrogen plume spontaneously ignited early in the release.
Facilitating the Safest Possible Transition from Fossil to Hydrogen Fuels- Hydrogen Executive Leadership Panel
Sep 2005
Publication
In recent years federal and state safety authorities have worked to bring emergency planners and responders together with industry the scientific community and consumers to ensure high levels of safety with gas and liquid pipelines and more recently with liquefied natural gas terminals. The U.S. Department of Transportation (DOT) is the federal authority on the safe transportation of energy and the National Association of State Fire Marshals (NASFM) represents state-level safety authorities. Together they have produced firefighter safety training materials technical guidance and information for use in communities considering new energy infrastructure and conducted research to support these activities. In 2004 the DOT-NASFM partnership established the Hydrogen Executive Leadership Panel (HELP) to ensure a safe transition from fossil fuels to hydrogen fuel cells. HELP brings together senior policy-level experts from all sectors to understand and recommend mitigation strategies for the risks associated with the transportation and use of hydrogen in motor vehicles. The initial group includes experts from the United States Canada and Europe. HELP will be supported by an advisory committee of emergency planners and responders—individuals well-equipped to describe real-world scenarios of greatest concern—and by a second advisory committee of engineers and scientists who will help translate the real-world scenarios into useful technical solutions. By September 2005 HELP expects to define the initial real-world scenarios of greatest concern and bring together teams of experts to collaborate with automakers energy producers government authorities consumers and public safety officials. Much work lies ahead including creating guidance for hydrogen powered automobiles emergency response safety training establishing test methods to reflect real-world incident scenarios and modifying state and local building and fire codes. The HELP leadership will present its strategic plan and first report at the International Conference on Hydrogen Safety in September 2005.
Evaluation of Safety Distances Related to Unconfined Hydrogen Explosions
Sep 2005
Publication
A simple approximate method for evaluation of blast effects and safety distances for unconfined hydrogen explosions is presented. The method includes models for flame speeds hydrogen distribution blast parameters and blast damage criteria. An example of the application of this methodology for hydrogen releases in three hypothetical obstructed areas with different levels of congestion is presented. The severity of the blast effect of unconfined hydrogen explosions is shown to depend strongly on the level of congestion for relatively small releases. Extremely large releases of hydrogen are predicted to be less sensitive to the congestion level.
Hydrogen Flames in Tubes- Critical Run-up Distances
Sep 2007
Publication
The hazard associated with flame acceleration to supersonic speeds in hydrogen mixtures is discussed. A set of approximate models for evaluation of the run-up distances to supersonic flames in relatively smooth tubes and tubes with obstacles is presented. The model for smooth tubes is based on general relationships between the flame area turbulent burning velocity and the flame speed combined with an approximate description for the boundary layer thickness ahead of an accelerated flame. The unknown constants of the model are evaluated using experimental data. This model is then supplemented with the model for the minimum run-up distance for FA in tubes with obstacles developed earlier. On the basis of these two models solutions for the determination of the critical runup distances for FA and deflagration to detonation transition in tubes and channels for various hydrogen mixtures initial temperature and pressure tube size and tube roughness are presented.
A Rural Hydrogen Transportation Test Bed
Sep 2007
Publication
The University of Missouri-Rolla (UMR) through a hydrogen internal combustion engine vehicle evaluation participation agreement with the Ford Motor Company will establish a commuter bus service and hydrogen refueling at a station in rural Missouri near Ft. Leonard Wood (FLW). Initiated by a request from the U.S. Army Maneuver Support Center at FLW UMR is leading the effort to launch the commuter service between FLW and the neighboring towns of Rolla and Lebanon Missouri each of which are located approximately 40 km from the military base on Interstate-44 highway. The broad research training and education agenda for the rural hydrogen transportation test bed is to develop demonstrate evaluate and promote safe hydrogen-based technologies in a real world environment. With funds provided by the Defense Logistics Agency through the Air Force Research Laboratory this hydrogen initiative will build and operate a hydrogen fueling facility that includes on-site generation of hydrogen through electrolysis as well as selling a range of other traditional and alternative fuels.
Risk Assessment for Hydrogen Codes and Standards
Sep 2005
Publication
The development and promulgation of codes and standards are essential to establish a market-receptive environment for commercial hydrogen-based products and systems. The focus of the U.S. Department of Energy (DOE) is to conduct the research and development (R&D) needed to strengthen the scientific basis for technical requirements incorporated in national and international standards codes and regulations. In the U.S. the DOE and its industry partners have formed a Codes and Standards Tech Team (CSTT) to help guide the R&D. The CSTT has adopted an R&D Roadmap to achieve a substantial and verified database of the properties and behaviour of hydrogen and the performance characteristics of emerging hydrogen technology applications sufficient to enable the development of effective codes and standards for these applications. However to develop a more structured approach to the R&D described above the CSTT conducted a workshop on Risk Assessment for Hydrogen Codes and Standards in March 2005. The purpose of the workshop was to attain a consensus among invited experts on the protocols and data needed to address the development of risk-informed standards codes and regulations for hydrogen used as an energy carrier by consumers. Participants at the workshop identified and assessed requirements methodologies and applicability of risk assessment (RA) tools to develop a framework to conduct RA activities to address for example hydrogen fuel distribution delivery on-site storage and dispensing and hydrogen vehicle servicing and parking. The CSTT was particularly interested in obtaining the advice of RA experts and representatives of standards and model code developing organizations and industry on how data generated by R&D can be turned into information that is suitable for hydrogen codes and standards development. The paper reports on the results of the workshop and the RA activities that the DOE’s program on hydrogen safety codes and standards will undertake. These RA activities will help structure a comprehensive R&D effort that the DOE and its industry partners are undertaking to obtain the data and conduct the analysis and testing needed to establish a scientific and technical basis for hydrogen standards codes and regulations.
Validation of Flacs-Hydrogen CFD Consequence Prediction Model Against Large Scale H2 Explosion Experiments in the Flame Facility
Sep 2005
Publication
The FLACS CFD-tool for consequence prediction has been developed continuously since 1980. The initial focus was explosion safety on offshore oil platforms in recent years the tool is also applied to study dispersion hydrogen safety dust explosions and more. A development project sponsored by Norsk Hydro Statoil and Ishikawajima Heavy Industries (IHI) was carried out to improve the modelling and validation of hydrogen dispersion and explosions. In this project GexCon carried out 200 small-scale experiments on dispersion and explosion with H2 and mixtures with H2 and CO or N2. Experiments with varying confinement congestion concentration and ignition location were performed. Since the main purpose of the tests was to produce good validation data all tests were simulated with the FLACS-HYDROGEN tool. The simulations confirmed the ability to predict explosions effects for the wide range of scenarios studied. A few examples of comparisons will be shown. To build confidence in a consequence prediction model it is important that the scales used for validation are as close as possible to reality. Since the hazard to people and facilities and the risk will generally increase with scale validation against large-scale experiments is important. In the 1980s a series of large-scale explosion experiments with H2 was carried out in the Sandia FLAME facility and sponsored by the US Nuclear Regulatory Commission. The FLAME facility is a 30.5m x 1.83m x 2.44m channel tests were performed with H2 concentrations from 7% to 30% with varying degree of top venting (0% 13% and 50%) and congestion (with or without baffles blocking 33% of the channel cross-section). A wide range of flame speeds and overpressures were observed. Comparisons are made between FLACS simulations and FLAME tests. The main conclusion from this validation study is that the precision when predicting H2 explosion consequences with FLACS has been improved to a very acceptable level
Analysis of Buoyancy-driven Ventilation of Hydrogen from Buildings
Sep 2007
Publication
When hydrogen gas is used or stored within a building as with a hydrogen-powered vehicle parked in a residential garage any leakage of unignited H2 will mix with indoor air and may form a flammable mixture. One approach to safety engineering relies on buoyancy-driven passive ventilation of H2 from the building through vents to the outside. To discover relationships between design variables we combine two types of analysis: (1) a simplified 1-D steady-state analysis of buoyancy-driven ventilation and (2) CFD modelling using FLUENT 6.3. The simplified model yields a closed-form expression relating the H2 concentration to vent area height and discharge coefficient; leakage rate; and a stratification factor. The CFD modelling includes 3-D geometry; H2 cloud formation; diffusion momentum convection and thermal effects; and transient response. We modelled a typical residential two-car garage with 5 kg of H2 stored in a fuel tank; leakage rates of 5.9 to 82 L/min (tank discharge times of 12 hours to 1 week); a variety of vent sizes and heights; and both isothermal and nonisothermal conditions. This modelling indicates a range of the stratification factor needed to apply the simplified model for vent sizing as well as a more complete understanding of the dynamics of H2 movement within the building. A significant thermal effect occurs when outdoor temperature is higher than indoor temperature so that thermocirculation opposes the buoyancy-driven ventilation of H2. This circumstance leads to higher concentrations of H2 in the building relative to an isothermal case. In an unconditioned space such as a residential garage this effect depends on the thermal coupling of indoor air to outdoor air the ground (under a concrete slab floor) and an adjacent conditioned space in addition to temperatures. We use CFD modelling to explore the magnitude of this effect under rather extreme conditions.
Analysis of Jet Flames and Unignited Jets from Unintended Releases of Hydrogen
Sep 2007
Publication
A combined experimental and modeling program is being carried out at Sandia National Laboratories to characterize and predict the behavior of unintended hydrogen releases. In the case where the hydrogen leak remains unignited knowledge of the concentration field and flammability envelope is an issue of importance in determining consequence distances for the safe use of hydrogen. In the case where a high-pressure leak of hydrogen is ignited a classic turbulent jet flame forms. Knowledge of the flame length and thermal radiation heat flux distribution is important to safety. Depending on the effective diameter of the leak and the tank source pressure free jet flames can be extensive in length and pose significant radiation and impingement hazard resulting in consequence distances that are unacceptably large. One possible mitigation strategy to potentially reduce the exposure to jet flames is to incorporate barriers around hydrogen storage equipment. The reasoning is that walls will reduce the extent of unacceptable consequences due to jet releases resulting from accidents involving high-pressure equipment. While reducing the jet extent the walls may introduce other hazards if not configured properly. The goal of this work is to provide guidance on configuration and placement of these walls to minimize overall hazards using a quantitative risk assessment approach. Detailed Navier-Stokes calculations of jet flames and unignited jets are used to understand how hydrogen leaks and jet-flames interact with barriers. The effort is complemented by an experimental program that considers the interaction of jet flames and unignited jets with barriers.
Collaborative Activities On Hydrogen Safety under the International Energy Agency’s Hydrogen Implementing
Sep 2005
Publication
In October 2004 the International Energy Agency Hydrogen Implementing Agreement (www.ieahia.org) approved the initiation of a collaborative task on hydrogen safety. During the past twelve months a work plan has been established and several member countries have committed to participate. Because of the nature of the International Energy Agency which is an international agreement between governments it is hoped that such collaboration will complement other cooperative efforts to help build the technology base around which codes and standards can be developed. In this way the new task on hydrogen safety will further the IEA Hydrogen Agreement in fulfilling its mission to accelerate the commercial introduction of hydrogen energy. This paper describes the specific scope and work plan for the collaboration that has been developed to date.
Fundamental Safety Testing and Analysis of Solid State Hydrogen Storage Materials and Systems
Sep 2007
Publication
Hydrogen is seen as the future automobile energy storage media due to its inherent cleanliness upon oxidation and its ready utilization in fuel cell applications. Its physical storage in light weight low volume systems is a key technical requirement. In searching for ever higher gravimetric and volumetric density hydrogen storage materials and systems it is inevitable that higher energy density materials will be studied and used. To make safe and commercially acceptable systems it is important to understand quantitatively the risks involved in using and handling these materials and to develop appropriate risk mitigation strategies to handle unforeseen accidental events. To evaluate these materials and systems an IPHE sanctioned program was initiated in 2006 partnering laboratories from Europe North America and Japan. The objective of this international program is to understanding the physical risks involved in synthesis handling and utilization of solid state hydrogen storage materials and to develop methods to mitigate these risks. This understanding will support ultimate acceptance of commercially high density hydrogen storage system designs. An overview of the approaches to be taken to achieve this objective will be given. Initial experimental results will be presented on environmental exposure of NaAlH4 a candidate high density hydrogen storage compound. The tests to be shown are based on United Nations recommendations for the transport of hazardous materials and include air and water exposure of the hydride at three hydrogen charge levels in various physical configurations. Additional tests developed by the American Society for Testing and Materials were used to quantify the dust cloud ignition characteristics of this material which may result from accidental high energy impacts and system breach. Results of these tests are shown along with necessary risk mitigation techniques used in the synthesis and fabrication of a prototype hydrogen storage system.
Addressing Hydrogen Embrittlement of Metals in the Sae J2579 Fuel Cell Vehicle Tank Standard
Sep 2013
Publication
The SAE Technical Information Report (TIR) J2579 (Technical Information Report for Fuel Systems in Fuel Cell and Other Hydrogen Vehicles) has been created to address the safety performance of hydrogen storage and handling systems on vehicles. Safety qualification of the compressed hydrogen storage system is demonstrated through performance testing on prototype containment vessels. The two performance tests currently included in the SAE J2579 for evaluating unacceptable leakage and burst do not account for the potential effects of hydrogen embrittlement on structural integrity. This report describes efforts to address hydrogen embrittlement of structural metals in the framework of performance-based safety qualification. New safety qualification pathways that account for hydrogen embrittlement in the SAE J2579 include an additional pneumatic performance test using hydrogen gas or materials tests that demonstrate acceptable hydrogen embrittlement resistance of candidate structural metals.
The Hydrogen Executive Leadership Panel (HELP) Initiative for Emergency Responder Training
Sep 2007
Publication
In close cooperation with their Canadian counterparts United States public safety authorities are taking the first steps towards creating a proper infrastructure to ensure the safe use of the new hydrogen fuel cells now being introduced commercially. Currently public safety officials are being asked to permit hydrogen fuel cells for stationary power and as emergency power backups for the telecommunications towers that exist everywhere. Consistent application of the safety codes is difficult – in part because it is new – yet it is far more complex to train emergency responders to deal safely with the inevitable hydrogen incidents. The US and Canadian building and fire codes and standards are similar but not identical. The US and Canadian rules are unlikely to be useful to other nations without modification to suit different regulatory systems. However emergency responder safety training is potentially more universal. The risks strategies and tactics are unlikely to differ much by region. The Hydrogen Executive Leadership Panel (HELP) made emergency responder safety training its first priority because the transition to hydrogen depends on keeping incidents small and inoffensive and the public and responders safe from harm. One might think that advising 1.2 million firefighters and 800000 law enforcement officers about hydrogen risks is no more complicated than adding guidance to a website. One would be wrong. The term “training” has specific legal implications which may vary by state. For hazardous materials federal requirements apply. Insurance companies place training requirements on the policies they sell to fire departments including the thousands of small all-volunteer departments which may operate as private corporations. Union contracts may define training and promotions may be based on satisfactorily completed certain levels of training. Emergency responders could no sooner learn how to extinguish a<br/>hydrogen fire by reading a webpage than a person could learn to ride a bicycle by reading a book. Procedures must be learned by listening reading and then doing. Regular practice is necessary. As new hydrogen applications are commercialized additional responder training may be necessary. This highlights another obstacle emergency responders’ ability to travel distances and take the time to undergo training. Historically fire academies established adjunct instructor programs and satellite academies to bring the training to firefighters. The large well-equipped academies are typically used for specialized training. States rarely have enough instructors and instructors often must take the time to create a course outline research each point and produce a program that is informative useful and holds the attention of responders. The challenge of training emergency responders seems next to impossible but public safety authorities are asked to tackle the impossible every day and a model exists to move forward in the U.S. Over the past few years the National Association of State Fire Marshals and U.S. Department of Transportation enlisted the help of emergency responders and industry to create a standardized approach to train emergency responders to deal with pipeline incidents. A curriculum and training materials were created and more than 26000 sets have been distributed for free to public safety agencies nationwide. More than 8000 instructors have been trained to use these materials that are now part of the regular training in 23 states. Using this model HELP intends to ensure that all emergency responders are trained to address hydrogen risks. The model and the rigorous scenario analysis and review used to developing the operational and technical training is addressed in this paper.
Incident Reporting- Learning from Experience
Sep 2007
Publication
Experience makes a superior teacher. Sharing the details surrounding safety events is one of the best ways to help prevent their recurrence elsewhere. This approach requires an open non-punitive environment to achieve broad benefits. The Hydrogen Incident Reporting Tool (www.h2incidents.org) is intended to facilitate the sharing of lessons learned and other relevant information gained from actual experiences using and working with hydrogen and hydrogen systems. Its intended audience includes those involved in virtually any aspect of hydrogen technology systems and use with an emphasis towards energy and transportation applications. The database contains records of safety events both publicly available and/or voluntarily submitted. Typical records contain a general description of the occurrence contributing factors equipment involved and some detailing of consequences and changes that have been subsequently implemented to prevent recurrence of similar events in the future. The voluntary and confidential nature and other characteristics surrounding the database mean that any analysis of apparent trends in its contents cannot be considered statistically valid for a universal population. A large portion of reported incidents have occurred in a laboratory setting due to the typical background of the reporting projects for example. Yet some interesting trends are becoming apparent even at this early stage of the database’s existence and general lessons can already be taken away from these experiences. This paper discusses the database and a few trends that have already become apparent for the reported incidents. Anticipated future uses of this information are also described. This paper is intended to encourage wider participation and usage of the incidents reporting database and to promote the safety benefits offered by its contents.
Risk-Informed Process and Tools for Permitting Hydrogen Fueling Stations
Sep 2007
Publication
The permitting process for hydrogen fueling stations varies from country to country. However a common step in the permitting process is the demonstration that the proposed fueling station meets certain safety requirements. Currently many permitting authorities rely on compliance with well known codes and standards as a means to permit a facility. Current codes and standards for hydrogen facilities require certain safety features specify equipment made of material suitable for hydrogen environment and include separation or safety distances. Thus compliance with the code and standard requirements is widely accepted as evidence of a safe design. However to ensure that a hydrogen facility is indeed safe the code and standard requirements should be identified using a risk-informed process that utilizes an acceptable level of risk. When compliance with one or more code or standard requirements is not possible an evaluation of the risk associated with the exemptions to the requirements should be understood and conveyed to the Authority Having Jurisdiction (AHJ). Establishment of a consistent risk assessment toolset and associated data is essential to performing these risk evaluations. This paper describes an approach for risk-informing the permitting process for hydrogen fueling stations that relies primarily on the establishment of risk-informed codes and standards. The proposed risk-informed process begins with the establishment of acceptable risk criteria associated with the operation of hydrogen fueling stations. Using accepted Quantitative Risk Assessment (QRA) techniques and the established risk criteria the minimum code and standard requirements necessary to ensure the safe operation of hydrogen facilities can be identified. Risk informed permitting processes exist in some countries and are being developed in others. To facilitate consistent risk-informed approaches the participants in the International Energy Agency (IEA) Task 19 on hydrogen safety are working to identify acceptable risk criteria QRA models and supporting data.
Hydrogen Safety and Permitting Hydrogen Fueling Stations
Sep 2007
Publication
Two key aspects of hydrogen safety are (1) incorporating data and analysis from research development and demonstration (RD&D) into the codes and standards development process; and (2) adopting and enforcing these codes and standards by state and local permitting officials. This paper describes work that the U.S. Department of Energy (DOE) is sponsoring to address these aspects of hydrogen safety. For the first DOE is working with the automobile and energy industries to identify and address high priority RD&D to establish a sound scientific basis for requirements that are incorporated in hydrogen codes and standards. The high priority RD&D needs are incorporated and tracked in an RD&D Roadmap adopted by the Codes and Standards Technical Team of the FreedomCAR and Fuel Partnership. DOE and its national laboratories conduct critical RD&D and work with key standards and model code development organizations to help incorporate RD&D results into the codes and standards process. To address the second aspect DOE has launched an initiative to facilitate the permitting process for hydrogen fueling stations (HFS). A key element of this initiative will be a Web-based information repository a toolkit that includes information fact sheets networking charts to encourage information exchange among code officials who have permitted or are in the process of permitting HFS templates to show whether a proposed station footprint conforms to requirements in the jurisdiction and a database of requirements incorporated in key codes and standards. The information repository will be augmented by workshops for code officials and station developers in jurisdictions that are likely to have HFS in the near future.
The Hydrogen Safety Program of the US Department of Energy
Sep 2005
Publication
Demonstrated safety in the production distribution and use of hydrogen will be critical to successful implementation of a hydrogen infrastructure. Recognizing the importance of this issue the U.S. Department of Energy has established the Hydrogen Safety Program to ensure safe operations of its hydrogen research and development program as well as to identify and address needs for new knowledge and technologies in the future hydrogen economy. Activities in the Safety Program range across the entire safety spectrum including: R&D devoted to investigation of hydrogen behaviour physical characteristics materials compatibility and risk analysis; inspection and investigation into the safety procedures and practices of all hydrogen projects supported by DOE funds; development of critical technologies for safe hydrogen systems such as sensors and design techniques; and safety training and education for emergency responders code inspectors and the general public. Throughout its activities the Safety Program encourages the open sharing of information to enable widespread benefit from any lessons learned or new information developed.
This paper provides detailed descriptions of the various activities of the DOE Hydrogen Safety Program and includes some example impacts already achieved from its implementation.
This paper provides detailed descriptions of the various activities of the DOE Hydrogen Safety Program and includes some example impacts already achieved from its implementation.
Achieving High-rate Hydrogen Recovery from Wastewater Using Customizable Alginate Polymer Gel Matrices Encapsulating Biomass
Jul 2018
Publication
In addition to methane gas higher-value resources such as hydrogen gas are produced during anaerobic wastewater treatment. They are however immediately consumed by other organisms. To recover these high-value resources not only do the desired phenotypes need to be retained in the anaerobic reactor but the undesired ones need to be washed out. In this study a well-established alginate-based polymer gel with and without a coating layer was used to selectively encapsulate hydrogen-producing biomass in beads to achieve high-rate recovery of hydrogen during anaerobic wastewater treatment. The effect of cross-linking agents Ca2+ Sr2+ and Ba2+ as well as a composite coating on the beads consisting of alternating layers of polyethylenimine and silica hydrogel were investigated with respect to their performance specifically their mass transfer characteristics and their differential ability to retain the encapsulated biomass. Although the coating reduced the escape rate of encapsulated biomass from the beads all alginate polymer matrices without coating effectively retained biomass. Fast diffusion of dissolved organic carbon (DOC) through the polymer gel was observed in both Ca-alginate and Sr-alginate without coating. The coating however decreased either the diffusivity or the permeability of the DOC depending on whether the DOC was from synthetic wastewater (more lipids and proteins) or real brewery wastewater (more sugars). Consequently the encapsulation system with coating became diffusion limited when brewery wastewater with high chemical oxygen demand was fed resulting in a lower hydrogen production rate than the uncoated encapsulation systems. In all cases the encapsulated biomass was able to produce hydrogen even at a hydraulic residence time of 45 min. Although there are limitations to this system the used of encapsulated biomass for resource recovery from wastewater shows promise particularly for high-rate systems in which the retention of specific phenotypes is desired.
Low-carbon Hydrogen Via Integration of Steam Methane Reforming with Molten Carbonate Fuel Cells at Low Fuel Utilization
Feb 2021
Publication
Hydrogen production is critical to many modern chemical processes – ammonia synthesis petroleum refining direct reduction of iron and more. Conventional approaches to hydrogen manufacture include steam methane reforming and autothermal reforming which today account for the lion's share of hydrogen generation. Without CO2 capture these processes emit about 8.7 kg of CO2 for each kg of H2 produced. In this study a molten carbonate fuel cell system with CO2 capture is proposed to retrofit the flue gas stream of an existing Steam Methane Reforming plant rated at 100000 Nm3 h−1 of 99.5% pure H2. The thermodynamic analysis shows direct CO2 emissions can be reduced by more than 95% to 0.4 to 0.5 kg CO2 /kg H2 while producing 17% more hydrogen (with an increase in natural gas input of approximately 37%). Because of the additional power and hydrogen generation of the carbonate fuel cell the efficiency debit associated with CO2 capture is quite small reducing the SMR efficiency from 76.6% without capture to 75.6% with capture. In comparison the use of standard amine technology for CO2 capture reduces the efficiency below 70%. This demonstrates the synergistic nature of the carbonate fuel cells which can reform natural gas to H2 while simultaneously capturing CO2 from the SMR flue gas and producing electricity giving rise to a total system with very low emissions yet high efficiency.
International Association for Hydrogen Safety ‘Research Priorities Workshop’, September 2018, Buxton, UK
Sep 2018
Publication
Hydrogen has the potential to be used by many countries as part of decarbonising the future energy system. Hydrogen can be used as a fuel ‘vector’ to store and transport energy produced in low-carbon ways. This could be particularly important in applications such as heating and transport where other solutions for low and zero carbon emission are difficult. To enable the safe uptake of hydrogen technologies it is important to develop the international scientific evidence base on the potential risks to safety and how to control them effectively. The International Association for Hydrogen Safety (known as IA HySAFE) is leading global efforts to ensure this. HSE hosted the 2018 IA HySAFE Biennial Research Priorities Workshop. A panel of international experts presented during nine key topic sessions: (1) Industrial and National Programmes; (2) Applications; (3) Storage; (4) Accident Physics – Gas Phase; (5) Accident Physics – Liquid/ Cryogenic Behaviour; (6) Materials; (7) Mitigation Sensors Hazard Prevention and Risk Reduction; (8) Integrated Tools for Hazard and Risk Assessment; (9) General Aspects of Safety.<br/>This report gives an overview of each topic made by the session chairperson. It also gives further analysis of the totality of the evidence presented. The workshop outputs are shaping international activities on hydrogen safety. They are helping key stakeholders to identify gaps in knowledge and expertise and to understand and plan for potential safety challenges associated with the global expansion of hydrogen in the energy system.
Design of a Methanol Reformer for On-board Production of Hydrogen as Fuel for a 3 kW High-Temperature Proton Exchange Membrane Fuel Cell Power System
Sep 2020
Publication
The method of Computational Fluid Dynamics is used to predict the process parameters and select the optimum operating regime of a methanol reformer for on-board production of hydrogen as fuel for a 3 kW High-Temperature Proton Exchange Membrane Fuel Cell power system. The analysis uses a three reactions kinetics model for methanol steam reforming water gas shift and methanol decomposition reactions on Cu/ZnO/Al2O3 catalyst. Numerical simulations are performed at single channel level for a range of reformer operating temperatures and values of the molar flow rate of methanol per weight of catalyst at the reformer inlet. Two operating regimes of the fuel processor are selected which offer high methanol conversion rate and high hydrogen production while simultaneously result in a small reformer size and a reformate gas composition that can be tolerated by phosphoric acid-doped high temperature membrane electrode assemblies for proton exchange membrane fuel cells. Based on the results of the numerical simulations the reactor is sized and its design is optimized.
Research and Development of Hydrogen Carrier Based Solutions for Hydrogen Compression and Storage
Aug 2022
Publication
Martin Dornheim,
Lars Baetcke,
Etsuo Akiba,
Jose-Ramón Ares,
Tom Autrey,
Jussara Barale,
Marcello Baricco,
Kriston Brooks,
Nikolaos Chalkiadakis,
Véronique Charbonnier,
Steven Christensen,
José Bellosta von Colbe,
Mattia Costamagna,
Erika Michela Dematteis,
Jose-Francisco Fernández,
Thomas Gennett,
David Grant,
Tae Wook Heo,
Michael Hirscher,
Katherine Hurst,
Mykhaylo V. Lototskyy,
Oliver Metz,
Paola Rizzi,
Kouji Sakaki,
Sabrina Sartori,
Emmanuel Stamatakis,
Alastair D. Stuart,
Athanasios Stubos,
Gavin Walker,
Colin Webb,
Brandon Wood,
Volodymyr A. Yartys and
Emmanuel Zoulias
Industrial and public interest in hydrogen technologies has risen strongly recently as hydrogen is the ideal means for medium to long term energy storage transport and usage in combination with renewable and green energy supply. In a future energy system the production storage and usage of green hydrogen is a key technology. Hydrogen is and will in future be even more used for industrial production processes as a reduction agent or for the production of synthetic hydrocarbons especially in the chemical industry and in refineries. Under certain conditions material based systems for hydrogen storage and compression offer advantages over the classical systems based on gaseous or liquid hydrogen. This includes in particular lower maintenance costs higher reliability and safety. Hydrogen storage is possible at pressures and temperatures much closer to ambient conditions. Hydrogen compression is possible without any moving parts and only by using waste heat. In this paper we summarize the newest developments of hydrogen carriers for storage and compression and in addition give an overview of the different research activities in this field.
Hydrogen or Batteries for Grid Storage? A Net Energy Analysis
Apr 2015
Publication
Energy storage is a promising approach to address the challenge of intermittent generation from renewables on the electric grid. In this work we evaluate energy storage with a regenerative hydrogen fuel cell (RHFC) using net energy analysis. We examine the most widely installed RHFC configuration containing an alkaline water electrolyzer and a PEM fuel cell. To compare RHFC's to other storage technologies we use two energy return ratios: the electrical energy stored on invested (ESOIe) ratio (the ratio of electrical energy returned by the device over its lifetime to the electrical-equivalent energy required to build the device) and the overall energy efficiency (the ratio of electrical energy returned by the device over its lifetime to total lifetime electrical-equivalent energy input into the system). In our reference scenario the RHFC system has an ESOIeratio of 59 more favorable than the best battery technology available today (Li-ion ESOIe= 35). (In the reference scenario RHFC the alkaline electrolyzer is 70% efficient and has a stack lifetime of 100 000 h; the PEM fuel cell is 47% efficient and has a stack lifetime of 10 000 h; and the round-trip efficiency is 30%.) The ESOIe ratio of storage in hydrogen exceeds that of batteries because of the low energy cost of the materials required to store compressed hydrogen and the high energy cost of the materials required to store electric charge in a battery. However the low round-trip efficiency of a RHFC energy storage system results in very high energy costs during operation and a much lower overall energy efficiency than lithium ion batteries (0.30 for RHFC vs. 0.83 for lithium ion batteries). RHFC's represent an attractive investment of manufacturing energy to provide storage. On the other hand their round-trip efficiency must improve dramatically before they can offer the same overall energy efficiency as batteries which have round-trip efficiencies of 75–90%. One application of energy storage that illustrates the trade-off between these different aspects of energy performance is capturing overgeneration (spilled power) for later use during times of peak output from renewables. We quantify the relative energetic benefit of adding different types of energy storage to a renewable generating facility using [EROI]grid. Even with 30% round-trip efficiency RHFC storage achieves the same [EROI]grid as batteries when storing overgeneration from wind turbines because its high ESOIeratio and the high EROI of wind generation offset the low round-trip efficiency.
Large Transition State Stabilization From a Weak Hydrogen Bond
Jul 2020
Publication
A series of molecular rotors was designed to study and measure the rate accelerating effects of an intramolecular hydrogen bond. The rotors form a weak neutral O–H⋯O[double bond length as m-dash]C hydrogen bond in the planar transition state (TS) of the bond rotation process. The rotational barrier of the hydrogen bonding rotors was dramatically lower (9.9 kcal mol−1) than control rotors which could not form hydrogen bonds. The magnitude of the stabilization was significantly larger than predicted based on the independently measured strength of a similar O–H⋯O[double bond length as m-dash]C hydrogen bond (1.5 kcal mol−1). The origins of the large transition state stabilization were studied via experimental substituent effect and computational perturbation analyses. Energy decomposition analysis of the hydrogen bonding interaction revealed a significant reduction in the repulsive component of the hydrogen bonding interaction. The rigid framework of the molecular rotors positions and preorganizes the interacting groups in the transition state. This study demonstrates that with proper design a single hydrogen bond can lead to a TS stabilization that is greater than the intrinsic interaction energy which has applications in catalyst design and in the study of enzyme mechanisms.
Highly Porous Organic Polymers for Hydrogen Fuel Storage
Apr 2019
Publication
Hydrogen (H2) is one of the best candidates to replace current petroleum energy resources due to its rich abundance and clean combustion. However the storage of H2presents a major challenge. There are two methods for storing H2 fuel chemical and physical both of which have some advantages and disadvantages. In physical storage highly porous organic polymers are of particular interest since they are low cost easy to scale up metal-free and environmentally friendly.
In this review highly porous polymers for H2 fuel storage are examined from five perspectives:
(a) brief comparison of H2 storage in highly porous polymers and other storage media;
(b) theoretical considerations of the physical storage of H2 molecules in porous polymers;
(c) H2 storage in different classes of highly porous organic polymers;
(d) characterization of microporosity in these polymers; and
(e) future developments for highly porous organic polymers for H2 fuel storage. These topics will provide an introductory overview of highly porous organic polymers in H2 fuel storage.
In this review highly porous polymers for H2 fuel storage are examined from five perspectives:
(a) brief comparison of H2 storage in highly porous polymers and other storage media;
(b) theoretical considerations of the physical storage of H2 molecules in porous polymers;
(c) H2 storage in different classes of highly porous organic polymers;
(d) characterization of microporosity in these polymers; and
(e) future developments for highly porous organic polymers for H2 fuel storage. These topics will provide an introductory overview of highly porous organic polymers in H2 fuel storage.
Biomass Derived Porous Nitrogen Doped Carbon for Electrochemical Devices
Mar 2017
Publication
Biomass derived porous nanostructured nitrogen doped carbon (PNC) has been extensively investigated as the electrode material for electrochemical catalytic reactions and rechargeable batteries. Biomass with and without containing nitrogen could be designed and optimized to prepare PNC via hydrothermal carbonization pyrolysis and other methods. The presence of nitrogen in carbon can provide more active sites for ion absorption improve the electronic conductivity increase the bonding between carbon and sulfur and enhance the electrochemical catalytic reaction. The synthetic methods of natural biomass derived PNC heteroatomic co- or tri-doping into biomass derived carbon and the application of biomass derived PNC in rechargeable Li/Na batteries high energy density Li–S batteries supercapacitors metal-air batteries and electrochemical catalytic reaction (oxygen reduction and evolution reactions hydrogen evolution reaction) are summarized and discussed in this review. Biomass derived PNCs deliver high performance electrochemical storage properties for rechargeable batteries/supercapacitors and superior electrochemical catalytic performance toward hydrogen evolution oxygen reduction and evolution as promising electrodes for electrochemical devices including battery technologies fuel cell and electrolyzer.
Advanced Hydrogen and CO2 Capture Technology for Sour Syngas
Apr 2011
Publication
A key challenge for future clean power or hydrogen projects via gasification is the need to reduce the overall cost while achieving significant levels of CO2 capture. The current state of the art technology for capturing CO2 from sour syngas uses a physical solvent absorption process (acid gas removal–AGR) such as Selexol™ or Rectisol® to selectively separate H2S and CO2 from the H2. These two processes are expensive and require significant utility consumption during operation which only escalates with increasing levels of CO2 capture. Importantly Air Products has developed an alternative option that can achieve a higher level of CO2 capture than the conventional technologies at significantly lower capital and operating costs. Overall the system is expected to reduce the cost of CO2 capture by over 25%.<br/>Air Products developed this novel technology by leveraging years of experience in the design and operation of H2 pressure swing adsorption (PSA) systems in its numerous steam methane reformers. Commercial PSAs typically operate on clean syngas and thus need an upstream AGR unit to operate in a gasification process. Air Products recognized that a H2 PSA technology adapted to handle sour feedgas (Sour PSA) would enable a new and enhanced improvement to a gasification system. The complete Air Products CO2 Capture technology (CCT) for sour syngas consists of a Sour PSA unit followed by a low-BTU sour oxycombustion unit and finally a CO2 purification / compression system.
Validation of Leading Point Concept in RANS Simulations of Highly Turbulent Lean Syngas-air Flames with Well-pronounced Diffusional-thermal Effects
Jan 2021
Publication
While significant increase in turbulent burning rate in lean premixed flames of hydrogen or hydrogen-containing fuel blends is well documented in various experiments and can be explained by highlighting local diffusional-thermal effects capabilities of the vast majority of available models of turbulent combustion for predicting this increase have not yet been documented in numerical simulations. To fill this knowledge gap a well-validated Turbulent Flame Closure (TFC) model of the influence of turbulence on premixed combustion which however does not address the diffusional-thermal effects is combined with the leading point concept which highlights strongly perturbed leading flame kernels whose local structure and burning rate are significantly affected by the diffusional-thermal effects. More specifically within the framework of the leading point concept local consumption velocity is computed in extremely strained laminar flames by adopting detailed combustion chemistry and subsequently the computed velocity is used as an input parameter of the TFC model. The combined model is tested in RANS simulations of highly turbulent lean syngas-air flames that were experimentally investigated at Georgia Tech. The tests are performed for four different values of the inlet rms turbulent velocities different turbulence length scales normal and elevated (up to 10 atm) pressures various H2/CO ratios ranging from 30/70 to 90/10 and various equivalence ratios ranging from 0.40 to 0.80. All in all the performed 33 tests indicate that the studied combination of the leading point concept and the TFC model can predict well-pronounced diffusional-thermal effects in lean highly turbulent syngas-air flames with these results being obtained using the same value of a single constant of the combined model in all cases. In particular the model well predicts a significant increase in the bulk turbulent consumption velocity when increasing the H2/CO ratio but retaining the same value of the laminar flame speed.
Metal Hydride Hydrogen Compressors
Feb 2014
Publication
Metal hydride (MH) thermal sorption compression is an efficient and reliable method allowing a conversion of energy from heat into a compressed hydrogen gas. The most important component of such a thermal engine – the metal hydride material itself – should possess several material features in order to achieve an efficient performance in the hydrogen compression. Apart from the hydrogen storage characteristics important for every solid H storage material (e.g. gravimetric and volumetric efficiency of H storage hydrogen sorption kinetics and effective thermal conductivity) the thermodynamics of the metal–hydrogen systems is of primary importance resulting in a temperature dependence of the absorption/desorption pressures). Several specific features should be optimised to govern the performance of the MH-compressors including synchronisation of the pressure plateaus for multi-stage compressors reduction of slope of the isotherms and hysteresis increase of cycling stability and life time together with challenges in system design associated with volume expansion of the metal matrix during the hydrogenation.<br/>The present review summarises numerous papers and patent literature dealing with MH hydrogen compression technology. The review considers (a) fundamental aspects of materials development with a focus on structure and phase equilibria in the metal–hydrogen systems suitable for the hydrogen compression; and (b) applied aspects including their consideration from the applied thermodynamic viewpoint system design features and performances of the metal hydride compressors and major applications.
Black TiO2 for Solar Hydrogen Conversion
Feb 2017
Publication
Titanium dioxide (TiO2 ) has been widely investigated for photocatalytic H2 evolution and photoelectrochemical (PEC) water splitting since 1972. However its wide bandgap (3.0–3.2 eV) limits the optical absorption of TiO2 for sufficient utilization of solar energy. Blackening TiO2 has been proposed as an effective strategy to enhance its solar absorption and thus the photocatalytic and PEC activities and aroused widespread research interest. In this article we reviewed the recent progress of black TiO2 for photocatalytic H2 evolution and PEC water splitting along with detailed introduction to its unique structural features optical property charge carrier transfer property and related theoretical calculations. As summarized in this review article black TiO2 could be a promising candidate for photoelectrocatalytic hydrogen generation via water splitting and continuous efforts are deserved for improving its solar hydrogen efficiency.
Mapping of Hydrogen Fuel Quality in Europe
Nov 2020
Publication
As part of FCH-JU funded HyCoRA project running from 2014 to 2017 28 gaseous and 13 particulate samples were collected from hydrogen refuelling stations in Europe. Samples were collected with commercial sampling instruments and analysis performed in compliance with prevailing fuel quality standards. Sampling was conducted with focus on diversity in feedstock as well as commissioning date of the HRS. Results indicate that the strategy for sampling was good. No evidence of impurity cross-over was observed. Parallel samples collected indicate some variation in analytical results. It was however found that fuel quality was generally good. Fourteen analytical results were in violation with the fuel tolerance limits. Therefore eight or 29% of the samples were in violation with the fuel quality requirements. Nitrogen oxygen and organics were the predominant impurities quantified. Particulate impurities were found to be within fuel quality specifications. No correlation between fuel quality and hydrogen feedstock or HRS commissioning date was found. Nitrogen to oxygen ratios gave no indication of samples being contaminated by air. A comparison of analytical results between two different laboratories were conducted. Some difference in analytical results were observed.
Decarbonization Synergies From Joint Planning of Electricity and Hydrogen Production: A Texas Case Study
Oct 2020
Publication
Hydrogen (H2) shows promise as an energy carrier in contributing to emissions reductions from sectors which have been difficult to decarbonize like industry and transportation. At the same time flexible H2 production via electrolysis can also support cost-effective integration of high shares of variable renewable energy (VRE) in the power system. In this work we develop a least-cost investment planning model to co-optimize investments in electricity and H2 infrastructure to serve electricity and H2 demands under various low-carbon scenarios. Applying the model to a case study of Texas in 2050 we find that H2 is produced in approximately equal amounts from electricity and natural gas under the least-cost expansion plan with a CO2 price of $30–60/tonne. An increasing CO2 price favors electrolysis while increasing H2 demand favors H2 production from Steam Methane Reforming (SMR) of natural gas. H2 production is found to be a cost effective solution to reduce emissions in the electric power system as it provides flexibility otherwise provided by natural gas power plants and enables high shares of VRE with less battery storage. Additionally the availability of flexible electricity demand via electrolysis makes carbon capture and storage (CCS) deployment for SMR cost-effective at lower CO2 prices ($90/tonne CO2) than for power generation ($180/tonne CO2 ). The total emissions attributable to H2 production is found to be dependent on the H2 demand. The marginal emissions from H2 production increase with the H2 demand for CO2 prices less than $90/tonne CO2 due to shift in supply from electrolysis to SMR. For a CO2 price of $60/tonne we estimate the production weighted-average H2 price to be between $1.30–1.66/kg across three H2 demand scenarios. These findings indicate the importance of joint planning of electricity and H2 infrastructure for cost-effective energy system decarbonization.
Numerical Simulations of Cryogenic Hydrogen Cooling in Vortex Tubes with Smooth Transitions
Mar 2021
Publication
Improving efficiency of hydrogen cooling in cryogenic conditions is important for the wider applications of hydrogen energy systems. The approach investigated in this study is based on a Ranque-Hilsch vortex tube (RHVT) that generates temperature separation in a working fluid. The simplicity of RHVT is also a valuable characteristic for cryogenic systems. In the present work novel shapes of RHVT are computationally investigated with the goal to raise efficiency of the cooling process. Specifically a smooth transition is arranged between a vortex chamber where compressed gas is injected and the main tube with two exit ports at the tube ends. Flow simulations have been carried out using STAR-CCM+ software with the real-gas Redlich-Kwong model for hydrogen at temperatures near 70 K. It is determined that a vortex tube with a smooth transition of moderate size manifests about 7% improvement of the cooling efficiency when compared vortex tubes that use traditional vortex chambers with stepped transitions and a no-chamber setup with direct gas injection.
A Solar Thermal Sorption-enhanced Steam Methane Reforming (SE-SMR) Approach and its Performance Assessment
Feb 2022
Publication
This paper proposes an integration of concentrating solar power (CSP) with a sorption-enhanced steam methane reforming (SE-SMR) process and assesses its overall solar-to-fuel conversion performance. A thermodynamic treatment of the SE-SMR process for H2 production is presented and evaluated in an innovative two reactors system configuration using CSP as a heat input. Four metal carbonate/metal oxide pairs are considered and the equilibrium thermodynamics reveals that CaCO3/CaO pair is the most suitable candidate for this process. Additionally a reactor-scale thermodynamic model is developed to determine the optimum operating conditions for the process. For the carbonation step temperatures between 700 and 900 K and steam-to-methane ratio ≥4 are found to be the most favorable. Furthermore an advanced process model which utilizes operating conditions determined from the reactor-scale model is developed to evaluate the process efficiency. The model predicts that the proposed process can achieve a solar-to-fuel efficiency ~41% for calcination temperature of 1500 K and carbonation temperature of 800 K without considering any solid heat recovery. An additional 2.5% increase in the process efficiency is feasible with the consideration of the solid heat recovery. This study shows the thermodynamic feasibility of integrating the SE-SMR process with CSP technologies.
Towards Ecological Alternatives in Bearing Lubrication
Jun 2021
Publication
Hydrogen is the cleanest fuel available because its combustion product is water. The internal combustion engine can in principle and without significant modifications run on hydrogen to produce mechanical energy. Regarding the technological solution leading to compact engines a question to ask is the following: Can combustion engine systems be lubricated with hydrogen? In general since many applications such as in turbomachines is it possible to use the surrounding gas as a lubricant? In this paper journal bearings global parameters are calculated and compared for steady state and dynamic conditions for different gas constituents such as air pentafluoropropane helium and hydrogen. Such a bearing may be promising as an ecological alternative to liquid lubrication.
Microwave Absorption of Aluminum/Hydrogen Treated Titanium Dioxide Nanoparticles
Dec 2018
Publication
Interactions between incident electromagnetic energy and matter are of critical importance for numerous civil and military applications such as photocatalysis solar cells optics radar detection communications information processing and transport et al. Traditional mechanisms for such interactions in the microwave frequency mainly rely on dipole rotations and magnetic domain resonance. In this study we present the first report of the microwave absorption of Al/H2 treated TiO2 nanoparticles where the Al/H2 treatment not only induces structural and optical property changes but also largely improves the microwave absorption performance of TiO2 nanoparticles. Moreover the frequency of the microwave absorption can be finely controlled with the treatment temperature and the absorption efficiency can reach optimal values with a careful temperature tuning. A large reflection loss of −58.02 dB has been demonstrated with 3.1 mm TiO2 coating when the treating temperature is 700 °C. The high efficiency of microwave absorption is most likely linked to the disordering-induced property changes in the materials. Along with the increased microwave absorption properties are largely increased visible-light and IR absorptions and enhanced electrical conductivity and reduced skin-depth which is likely related to the interfacial defects within the TiO2 nanoparticles caused by the Al/H2 treatment.
Storable Energy Production from Wind over Water
Apr 2020
Publication
The current status of a project is described which aims to demonstrate the technical and economic feasibility of converting the vast wind energy available over the globe’s oceans and lakes into storable energy. To this end autonomous high-performance sailing ships are equipped with hydrokinetic turbines whose output is stored either in electric batteries or is fed into electrolysers to produce hydrogen which then is compressed and stored in tanks. In the present paper the previous analytical studies which showed the potential of this “energy ship concept” are summarized and progress on its hardware demonstration is reported involving the conversion of a model sailboat to autonomous operation. The paper concludes with a discussion of the potential of this concept to achieve the IPCC-mandated requirement of reducing the global CO2 emissions by about 45% by 2030 reaching net zero by 2050.
Raw Biomass Electroreforming Coupled to Green Hydrogen Generation
Mar 2021
Publication
Despite the tremendous progress of coupling organic electrooxidation with hydrogen generation in a hybrid electrolysis electroreforming of raw biomass coupled to green hydrogen generation has not been reported yet due to the rigid polymeric structures of raw biomass. Herein we electrooxidize the most abundant natural amino biopolymer chitin to acetate with over 90% yield in hybrid electrolysis. The overall energy consumption of electrolysis can be reduced by 15% due to the thermodynamically and kinetically more favorable chitin oxidation over water oxidation. In obvious contrast to small organics as the anodic reactant the abundance of chitin endows the new oxidation reaction excellent scalability. A solar-driven electroreforming of chitin and chitin-containing shrimp shell waste is coupled to safe green hydrogen production thanks to the liquid anodic product and suppression of oxygen evolution. Our work thus demonstrates a scalable and safe process for resource upcycling and green hydrogen production for a sustainable energy future.
Converting Sewage Water into H2 Fuel Gas Using Cu/CuO Nanoporous Photocatalytic Electrodes
Feb 2022
Publication
This work reports on H2 fuel generation from sewage water using Cu/CuO nanoporous (NP) electrodes. This is a novel concept for converting contaminated water into H2 fuel. The preparation of Cu/CuO NP was achieved using a simple thermal combustion process of Cu metallic foil at 550 ◦C for 1 h. The Cu/CuO surface consists of island-like structures with an inter-distance of 100 nm. Each island has a highly porous surface with a pore diameter of about 250 nm. X-ray diffraction (XRD) confirmed the formation of monoclinic Cu/CuO NP material with a crystallite size of 89 nm. The prepared Cu/CuO photoelectrode was applied for H2 generation from sewage water achieving an incident to photon conversion efficiency (IPCE) of 14.6%. Further the effects of light intensity and wavelength on the photoelectrode performance were assessed. The current density (Jph) value increased from 2.17 to 4.7 mA·cm−2 upon raising the light power density from 50 to 100 mW·cm−2 . Moreover the enthalpy (∆H*) and entropy (∆S*) values of Cu/CuO electrode were determined as 9.519 KJ mol−1 and 180.4 JK−1 ·mol−1 respectively. The results obtained in the present study are very promising for solving the problem of energy in far regions by converting sewage water to H2 fuel.
Recent Advances in Carbon Dioxide Conversion: A Circular Bioeconomy Perspective
Jun 2021
Publication
Managing the concentration of atmospheric CO2 requires a multifaceted engineering strategy which remains a highly challenging task. Reducing atmospheric CO2 (CO2R) by converting it to value-added chemicals in a carbon neutral footprint manner must be the ultimate goal. The latest progress in CO2R through either abiotic (artificial catalysts) or biotic (natural enzymes) processes is reviewed herein. Abiotic CO2R can be conducted in the aqueous phase that usually leads to the formation of a mixture of CO formic acid and hydrogen. By contrast a wide spectrum of hydrocarbon species is often observed by abiotic CO2R in the gaseous phase. On the other hand biotic CO2R is often conducted in the aqueous phase and a wide spectrum of value-added chemicals are obtained. Key to the success of the abiotic process is understanding the surface chemistry of catalysts which significantly governs the reactivity and selectivity of CO2R. However in biotic CO2R operation conditions and reactor design are crucial to reaching a neutral carbon footprint. Future research needs to look toward neutral or even negative carbon footprint CO2R processes. Having a deep insight into the scientific and technological aspect of both abiotic and biotic CO2R would advance in designing efficient catalysts and microalgae farming systems. Integrating the abiotic and biotic CO2R such as microbial fuel cells further diversifies the spectrum of CO2R.
Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project
Dec 2011
Publication
This report summarizes the work conducted under U.S. Department of Energy (DOE) under contract DE-FC36-04GO14285 by Mercedes-Benz & Research Development North America (MBRDNA) Chrysler Daimler Mercedes Benz USA (MBUSA) BP DTE Energy and NextEnergy to validate fuel cell technologies for infrastructure transportation as well as assess technology and commercial readiness for the market. The Mercedes Team together with its partners tested the technology by operating and fuelling hydrogen fuel cell vehicles under real world conditions in varying climate terrain and driving conditions. Vehicle and infrastructure data was collected to monitor the progress toward the hydrogen vehicle and infrastructure performance targets of $2.00 to 3.00/gge hydrogen production cost and 2000-hour fuel cell durability. Finally to prepare the public for a hydrogen economy outreach activities were designed to promote awareness and acceptance of hydrogen technology. DTE BP and NextEnergy established hydrogen filling stations using multiple technologies for on-site hydrogen generation storage and dispensing. DTE established a hydrogen station in Southfield Michigan while NextEnergy and BP worked together to construct one hydrogen station in Detroit. BP constructed another fueling station in Burbank California and provided a full-time hydrogen trailer at San Francisco California and a hydrogen station located at Los Angeles International Airportmore.
Evaluation of Decarbonization Technologies for ASEAN Countries via an Integrated Assessment Tool
May 2022
Publication
A new assessment tool for evaluating decarbonization technologies that considers each technology’s sustainability security affordability readiness and impact for a specific country is proposed. This tool is applied to a set of decarbonization technologies for the power transport and industry sectors for the ten Southeast Asian countries that constitute ASEAN. This results in a list of the most promising decarbonization technologies as well as the remaining issues that need more research and development. This study reveals several common themes for ASEAN’s decarbonization. First carbon capture and storage (CCS) is a key technology for large-scale CO2 emission. Second for countries that rely heavily on coal for power generation switching to gas can halve their CO2 emission in the power sector and should be given high priority. Third hydropower and bioenergy both have high potential for the majority of ASEAN countries if their sustainability issues can be resolved satisfactorily. Fourth replacing conventional vehicles by electric vehicles is the overarching theme in the road transport sector but will result in increased demand for electricity. In the medium to long term the use of hydrogen for marine fuel and biofuels for aviation fuel are preferred solutions for the marine and aviation transport sectors. Fifth for the industry sector installing CCS in industrial plants should be given priority but replacing fossil fuels by blue hydrogen for high-temperature heating is the preferred long-term solution.
Metastable Metal Hydrides for Hydrogen Storage
Oct 2012
Publication
The possibility of using hydrogen as a reliable energy carrier for both stationary and mobile applications has gained renewed interest in recent years due to improvements in high temperature fuel cells and a reduction in hydrogen production costs. However a number of challenges remain and new media are needed that are capable of safely storing hydrogen with high gravimetric and volumetric densities. Metal hydrides and complex metal hydrides offer some hope of overcoming these challenges; however many of the high capacity “reversible” hydrides exhibit a large endothermic decomposition enthalpy making it difficult to release the hydrogen at low temperatures. On the other hand the metastable hydrides are characterized by a low reaction enthalpy and a decomposition reaction that is thermodynamically favorable under ambient conditions. The rapid low temperature hydrogen evolution rates that can be achieved with these materials offer much promise for mobile PEM fuel cell applications. However a critical challenge exists to develop new methods to regenerate these hydrides directly from the reactants and hydrogen gas. This spotlight paper presents an overview of some of the metastable metal hydrides for hydrogen storage and a few new approaches being investigated to address the key challenges associated with these materials.
Physicochemical Properties of Proton-conducting SmNiO3 Epitaxial Films
Mar 2019
Publication
Proton conducting SmNiO3 (SNO) thin films were grown on (001) LaAlO3 substrates for systematically investigating the proton transport properties. X-ray Diffraction and Atomic Force Microscopy studies reveal that the as-grown SNO thin films have good single crystallinity and smooth surface morphology. The electrical conductivity measurements in air indicate a peak at 473 K in the temperature dependence of the resistance of the SNO films probably due to oxygen loss on heating. A Metal-Insulator-Transition occurs at 373 K for the films after annealing at 873 K in air. In a hydrogen atmosphere (3% H2/97% N2) an anomalous peak in the resistance is found at 685 K on the first heating cycle. Electrochemical Impedance Spectroscopy studies as a function of temperature indicate that the SNO films have a high ionic conductivity (0.030 S/cm at 773 K) in a hydrogen atmosphere. The activation energy for proton conductivity was determined to be 0.23 eV at 473–773 K and 0.37 eV at 773–973 K respectively. These findings demonstrate that SNO thin films have good proton conductivity and are good candidate electrolytes for low temperature proton-conducting Solid Oxide Fuel Cells.
Comparison of Conventional vs. Modular Hydrogen Refuelling Stations and On-Site Production vs. Delivery
Mar 2017
Publication
To meet the needs of public and private stakeholders involved in the development construction and operation of hydrogen fuelling stations needed to support the widespread roll-out of hydrogen fuel cell electric vehicles this work presents publicly available station templates and analyses. These ‘Reference Stations’ help reduce the cost and speed the deployment of hydrogen stations by providing a common baseline with which to start a design enable quick assessment of potential sites for a hydrogen station identify contributors to poor economics and suggest areas of research. This work presents layouts bills of materials piping and instrumentation diagrams and detailed analyses of five new station designs. In the near term delivered hydrogen results in a lower cost of hydrogen compared to on-site production via steam methane reforming or electrolysis although the on-site production methods have other advantages. Modular station concepts including on-site production can reduce lot sizes from conventional assemble-on-site stations.
Water Photo-Oxidation Reaction on Clean and Doped Two-Dimensional Graphitic C2N
Apr 2020
Publication
In the search for new efficient photo-catalysts for hydrogen production through water splitting the main attention has been paid to tuning the band gap width and its position with respect to vacuum level. However actual electro-catalytic activity for the water oxidation reaction on a catalyst surface is no less important than those quantities. In this work we evaluate from first principles the thermodynamics of the reaction on relatively new candidates for water splitting: two-dimensional C2N and that doped with phosphorus. We find that the 4-step reaction usually expected for water splitting will not proceed on these systems resulting in oxygen atoms left strongly adsorbed to the surface. Another option a 3-step reaction is also found to be unfavorable. We also test an effect of higher oxygen coverage on the reaction thermodynamics as suggested elsewhere. We find that indeed the doubled O-coverage makes the 4-step reaction feasible for the doped C2N. However an unacceptably high anode potential is required to make this reaction proceed. We thus conclude that the materials under consideration may not be efficient electro-catalysts for water splitting.
Materials for Hydrogen-based Energy Storage - Past, Recent Progress and Future Outlook
Dec 2019
Publication
Michael Hirscher,
Volodymyr A. Yartys,
Marcello Baricco,
José Bellosta von Colbe,
Didier Blanchard,
Robert C. Bowman Jr.,
Darren P. Broom,
Craig Buckley,
Fei Chang,
Ping Chen,
Young Whan Cho,
Jean-Claude Crivello,
Fermin Cuevas,
William I. F. David,
Petra E. de Jongh,
Roman V. Denys,
Martin Dornheim,
Michael Felderhoff,
Yaroslav Filinchuk,
George E. Froudakis,
David M. Grant,
Evan MacA. Gray,
Bjørn Christian Hauback,
Teng He,
Terry D. Humphries,
Torben R. Jensen,
Sangryun Kim,
Yoshitsugu Kojima,
Michel Latroche,
Hai-wen Li,
Mykhaylo V. Lototskyy,
Joshua W. Makepeace,
Kasper T. Møller,
Lubna Naheed,
Peter Ngene,
Dag Noreus,
Magnus Moe Nygård,
Shin-ichi Orimo,
Mark Paskevicius,
Luca Pasquini,
Dorthe B. Ravnsbæk,
M. Veronica Sofianos,
Terrence J. Udovic,
Tejs Vegge,
Gavin Walker,
Colin Webb,
Claudia Weidenthaler and
Claudia Zlotea
Globally the accelerating use of renewable energy sources enabled by increased efficiencies and reduced costs and driven by the need to mitigate the effects of climate change has significantly increased research in the areas of renewable energy production storage distribution and end-use. Central to this discussion is the use of hydrogen as a clean efficient energy vector for energy storage. This review by experts of Task 32 “Hydrogen-based Energy Storage” of the International Energy Agency Hydrogen TCP reports on the development over the last 6 years of hydrogen storage materials methods and techniques including electrochemical and thermal storage systems. An overview is given on the background to the various methods the current state of development and the future prospects. The following areas are covered; porous materials liquid hydrogen carriers complex hydrides intermetallic hydrides electro-chemical storage of energy thermal energy storage hydrogen energy systems and an outlook is presented for future prospects and research on hydrogen-based energy storage
Quaternary Hydrides Pd1-y-zAgyCuzHx Embedded Atom Method Potentials for Hydrogen Energy Applications
Jan 2021
Publication
The Pd-H system has attracted extensive attention. Pd can absorb considerable amount of H at room temperature this ability is reversible so it is suitable for multiple energy applications. Pd-Ag alloys possess higher H permeability solubility and narrower miscibility gap with better mechanical properties than pure Pd but sulfur poisoning remains an issue. Pd-Cu alloys have excellent resistance to sulfur and carbon monoxide poisoning and hydrogen embrittlement good mechanical properties and broader temperature working environments over pure Pd but relatively lower hydrogen permeability and solubility than pure Pd and Pd-Ag alloys. This suggests that alloying Pd with Ag and Cu to create Pd-Ag-Cu ternary alloys can optimize the overall performance and substantially lowers the cost. Thus in this paper we provide the first embedded atom method potentials for the quaternary hydrides Pd1-y-zAgyCuzHx. The fully analytical potentials are fitted utilizing the central atom method without performing time-consuming molecular dynamics simulations.
A New Design Concept for Prevention of Hydrogen-induced Mechanical Degradation: Viewpoints of Metastability and High Entropy
Dec 2018
Publication
‟How crack growth is prevented” is key to improve both fatigue and monotonic fracture resistances under an influence of hydrogen. Specifically the key points for the crack growth resistance are hydrogen diffusivity and local ductility. For instance type 304 austenitic steels show high hydrogen embrittlement susceptibility because of the high hydrogen diffusivity of bcc (α´) martensite. In contrast metastability in specific austenitic steels enables fcc (γ) to hcp (ε) martensitic transformation which decreases hydrogen diffusivity and increases strength simultaneously. As a result even if hydrogen-assisted cracking occurs during monotonic tensile deformation the ε-martensite acts to arrest micro-damage evolution when the amount of ε-martensite is limited. Thus the formation of ε-martensite can decrease hydrogen embrittlement susceptibility in austenitic steels. However a considerable amount of ε-martensite is required when we attempt to have drastic improvements of work hardening capability and strength level with respect to transformation-induced plasticity effect. Since the hcp structure contains a less number of slip systems than fcc and bcc the less stress accommodation capacity often causes brittle-like failure when the ε-martensite fraction is large. Therefore ductility of ε-martensite is another key when we maximize the positive effect of ε-martensitic transformation. In fact ε-martensite in a high entropy alloy was recently found to be extraordinary ductile. Consequently the metastable high entropy alloys showed low fatigue crack growth rates in a hydrogen atmosphere compared with conventional metastable austenitic steels with α´-martensitic transformation. We here present effects of metastability to ε-phase and configurational entropy on hydrogen-induced mechanical degradation including monotonic tension properties and fatigue crack growth resistance.
Self-sustainable Protonic Ceramic Electrochemical cells Using a Triple Conducting Electrode for Hydrogen and Power Production
Apr 2020
Publication
The protonic ceramic electrochemical cell (PCEC) is an emerging and attractive technology that converts energy between power and hydrogen using solid oxide proton conductors at intermediate temperatures. To achieve efficient electrochemical hydrogen and power production with stable operation highly robust and durable electrodes are urgently desired to facilitate water oxidation and oxygen reduction reactions which are the critical steps for both electrolysis and fuel cell operation especially at reduced temperatures. In this study a triple conducting oxide of PrNi0.5Co0.5O3-δ perovskite is developed as an oxygen electrode presenting superior electrochemical performance at 400~600 °C. More importantly the self-sustainable and reversible operation is successfully demonstrated by converting the generated hydrogen in electrolysis mode to electricity without any hydrogen addition. The excellent electrocatalytic activity is attributed to the considerable proton conduction as confirmed by hydrogen permeation experiment remarkable hydration behavior and computations.
Hydrogen Station Location Planning via Geodesign in Connecticut: Comparing Optimization Models and Structured Stakeholder Collaboration
Nov 2021
Publication
Geodesign is a participatory planning approach in which stakeholders use geographic information systems to develop and vet alternative design scenarios in a collaborative and iterative process. This study is based on a 2019 geodesign workshop in which 17 participants from industry government university and non-profit sectors worked together to design an initial network of hydrogen refueling stations in the Hartford Connecticut metropolitan area. The workshop involved identifying relevant location factors rapid prototyping of station network designs and developing consensus on a final design. The geodesign platform which was designed specifically for facility location problems enables breakout groups to add or delete stations with a simple point-and-click operation view and overlay different map layers compute performance metrics and compare their designs to those of other groups. By using these sources of information and their own expert local knowledge participants recommended six locations for hydrogen refueling stations over two distinct phases of station installation. We quantitatively and qualitatively compared workshop recommendations to solutions of three optimal station location models that have been used to recommend station locations which minimize travel times from stations to population and traffic or maximize trips that can be refueled on origin–destination routes. In a post-workshop survey participants rated the workshop highly for facilitating mutual understanding and information sharing among stakeholders. To our knowledge this workshop represents the first application of geodesign for hydrogen refueling station infrastructure planning.
Safety and Other Considerations in the Development of a Hydrogen Fueling Protocol for Heavy-duty Vehicles
Sep 2021
Publication
Several manufacturers are developing heavy duty (HD) hydrogen stations and vehicles as zeroemissions alternatives to diesel and gasoline. In order to meet customer demands the new technology must be comparable to conventional approaches including safety reliability fueling times and final fill levels. For a large HD vehicle with a storage rated to 70 MPa nominal working pressure the goal to meet liquid fuel parity means providing 100 kg of hydrogen in 10 minutes. This paper summarizes the results to date of the PRHYDE project efforts to define the concepts of HD fueling which thereby lays the groundwork for the development of the safe and effective approach to filling these large vehicles. The project starts by evaluating the impact of several different assumptions such as the availability of static vehicle data (e.g. vehicle tank type and volume) and station data (e.g. expected station precooling capability) but also considers using real time dynamic data (e.g. vehicle tank gas temperature and pressure station gas temperature etc.) for optimisation to achieve safety and efficiency improvements. With this information the vehicle or station can develop multiple maps of fill time versus the hydrogen delivery temperature which are used to determine the speed of fueling. This will also allow the station or vehicle to adjust the rate of fueling as the station pre-cooling levels and other conditions change. The project also examines different steps for future protocol development such as communication of data between the vehicle and station and if the vehicle or station is controlling the fueling.
Ammonia Production from Clean Hydrogen and the Implications for Global Natural Gas Demand
Jan 2023
Publication
Non-energy use of natural gas is gaining importance. Gas used for 183 million tons annual ammonia production represents 4% of total global gas supply. 1.5-degree pathways estimate an ammonia demand growth of 3–4-fold until 2050 as new markets in hydrogen transport shipping and power generation emerge. Ammonia production from hydrogen produced via water electrolysis with renewable power (green ammonia) and from natural gas with CO2 storage (blue ammonia) is gaining attention due to the potential role of ammonia in decarbonizing energy value chains and aiding nations in achieving their net-zero targets. This study assesses the technical and economic viability of different routes of ammonia production with an emphasis on a systems level perspective and related process integration. Additional cost reductions may be driven by optimum sizing of renewable power capacity reducing losses in the value chain technology learning and scale-up reducing risk and a lower cost of capital. Developing certification and standards will be necessary to ascertain the extent of greenhouse gas emissions throughout the supply chain as well as improving the enabling conditions including innovative finance and de-risking for facilitating international trade market creation and large-scale project development.
Ignition of Hydrogen-air Mixtures Under Volumetric Expansion Conditions
Sep 2017
Publication
A better understanding of chemical kinetics under volumetric expansion is important for a number of situations relevant to industrial safety including detonation diffraction and direct initiation reflected shock-ignition at obstacles ignition behind a decaying shock among others. The ignition of stoichiometric hydrogen-air mixtures was studied using 0D numerical simulations with time-dependent specific volume variations. The competition between chemical energy release and expansion-induced cooling was characterized for different cooling rates and mathematical forms describing the shock decay rate. The critical conditions for reaction quenching were systematically determined and the thermo-chemistry dynamics were analyzed near the critical conditions.
Electrolyzers Enhancing Flexibility in Electric Grids
Nov 2017
Publication
This paper presents a real-time simulation with a hardware-in-the-loop (HIL)-based approach for verifying the performance of electrolyzer systems in providing grid support. Hydrogen refueling stations may use electrolyzer systems to generate hydrogen and are proposed to have the potential of becoming smarter loads that can proactively provide grid services. On the basis of experimental findings electrolyzer systems with balance of plant are observed to have a high level of controllability and hence can add flexibility to the grid from the demand side. A generic front end controller (FEC) is proposed which enables an optimal operation of the load on the basis of market and grid conditions. This controller has been simulated and tested in a real-time environment with electrolyzer hardware for a performance assessment. It can optimize the operation of electrolyzer systems on the basis of the information collected by a communication module. Real-time simulation tests are performed to verify the performance of the FEC-driven electrolyzers to provide grid support that enables flexibility greater economic revenue and grid support for hydrogen producers under dynamic conditions. The FEC proposed in this paper is tested with electrolyzers however it is proposed as a generic control topology that is applicable to any load.
Fracture Properties of Welded 304L in Hydrogen Environments
Sep 2021
Publication
Austenitic stainless steels are used for hydrogen containment of high-pressure hydrogen gas due to their ability to retain high fracture properties despite the degradation due to hydrogen. Forging and other strain-hardening processes are desirable for austenitic stainless steels to increase the material strength and thus accommodate higher stresses and reduce material costs. Welding is often necessary for assembling components but it represents an area of concern in pressure containment structures due to the potential for defects more environmentally susceptible microstructure and reduced strength. Electron beam (EB) welding represent an advanced joining process which has advantages over traditional arc welding techniques through reduced input heat and reduced heat-affected zone (HAZ) microstructure and thus present a means to maintain high strength and improve weld performance in hydrogen gas containment. In this study fracture coupons were extracted from EB welds in forged 304L and subjected to thermal gaseous hydrogen precharging at select pressures to introduce different levels of internal hydrogen content. Fracture tests were then performed on hydrogen precharged coupons at temperatures of both 293 K and 223 K. It was observed that fracture resistance (JH) was dependent on internal hydrogen concentration; higher hydrogen concentrations resulted in lower fracture resistance in both the forged 304L base material and the 304L EB welds. This trend was also apparent at both temperatures: 293 K and 223 K. EB weld samples however maintain high fracture resistance comparable to the forged 304L base material. The role of weld microstructure solidification on fracture is discussed.
Everything About Hydrogen Podcast: What's Brewing in the UK Clean Hydrogen Sector?
Dec 2021
Publication
Chris Jackson is the Founder and CEO of Protium Green Solutions based in London. Protium is a hydrogen energy services company that designs develops finances owns and operates clean hydrogen solutions for clients to achieve net zero energy emissions at their industrial/manufacturing sites. Chris will talk to us about the Protium story and also give us some insight into a major project that Protium recently announced in conjunction Budweiser Brewing Group UK&Ireland to explore the deployment of zero emission green hydrogen at Magor brewery in South Wales one of the largest breweries in the UK. To that end in order to get the full story about this project we are delighted to say that we have yet another great guest on this episode. Tom Brewer who leads Global Environmental Sustainability efforts at AB InBev the parent company of Budweiser Brewing Group will join us for the final segment of the show to talk about how hydrogen fits into AB InBev’s vision of a sustainable future for the company.
The podcast can be found on their website
The podcast can be found on their website
Study of the Microstructural and First Hydrogenation Properties of TiFe Alloy with Zr, Mn and V as Additives
Jul 2021
Publication
In this paper we report the effect of adding Zr + V or Zr + V + Mn to TiFe alloy on microstructure and hydrogen storage properties. The addition of only V was not enough to produce a minimum amount of secondary phase and therefore the first hydrogenation at room temperature under a hydrogen pressure of 20 bars was impossible. When 2 wt.% Zr + 2 wt.% V or 2 wt.% Zr + 2 wt.% V + 2 wt.% Mn is added to TiFe the alloy shows a finely distributed Ti2Fe-like secondary phase. These alloys presented a fast first hydrogenation and a high capacity. The rate-limiting step was found to be 3D growth diffusion controlled with decreasing interface velocity. This is consistent with the hypothesis that the fast reaction is likely to be the presence of Ti2Fe-like secondary phases that act as a gateway for hydrogen.
On the Climate Impacts of Blue Hydrogen Production
Nov 2021
Publication
Natural gas based hydrogen production with carbon capture and storage is referred to as blue hydrogen. If substantial amounts of CO2 from natural gas reforming are captured and permanently stored such hydrogen could be a low-carbon energy carrier. However recent research raises questions about the effective climate impacts of blue hydrogen from a life cycle perspective. Our analysis sheds light on the relevant issues and provides a balanced perspective on the impacts on climate change associated with blue hydrogen. We show that such impacts may indeed vary over large ranges and depend on only a few key parameters: the methane emission rate of the natural gas supply chain the CO2 removal rate at the hydrogen production plant and the global warming metric applied. State-of-the-art reforming with high CO2 capture rates combined with natural gas supply featuring low methane emissions does indeed allow for substantial reduction of greenhouse gas emissions compared to both conventional natural gas reforming and direct combustion of natural gas. Under such conditions blue hydrogen is compatible with low-carbon economies and exhibits climate change impacts at the upper end of the range of those caused by hydrogen production from renewable-based electricity. However neither current blue nor green hydrogen production pathways render fully “net-zero” hydrogen without additional CO2 removal.
Developing New Understanding of Photoelectrochemical Water Splitting Via In-situ Techniques: A Review on Recent Progress
Mar 2014
Publication
Photoelectrochemical (PEC) water splitting is a promising technology for solar hydrogen production to build a sustainable renewable and clean energy economy. Given the complexity of the PEC water splitting processes it is important to note that developing in-situ techniques for studying PEC water splitting presents a formidable challenge. This review is aimed at highlighting advantages and disadvantages of each technique while offering a pathway of potentially combining several techniques to address different aspects of interfacial processes in PEC water splitting. We reviewed recent progress in various techniques and approaches utilized to study PEC water splitting focusing on spectroscopic and scanning-probe methods.
Thermochemical Recuperation to Enable Efficient Ammonia-Diesel Dual-Fuel Combustion in a Compression Ignition Engine
Nov 2021
Publication
A thermochemical recuperation (TCR) reactor was developed and experimentally evaluated with the objective to improve dual-fuel diesel–ammonia compression ignition engines. The novel system simultaneously decomposed ammonia into a hydrogen-containing mixture to allow high diesel fuel replacement ratios and oxidized unburned ammonia emissions in the exhaust overcoming two key shortcomings of ammonia combustion in engines from the previous literature. In the experimental work a multi-cylinder compression ignition engine was operated in dual-fuel mode using intake-fumigated ammonia and hydrogen mixtures as the secondary fuel. A full-scale catalytic TCR reactor was constructed and generated the fuel used in the engine experiments. The results show that up to 55% of the total fuel energy was provided by ammonia on a lower heating value basis. Overall engine brake thermal efficiency increased for modes with a high exhaust temperature where ammonia decomposition conversion in the TCR reactor was high but decreased for all other modes due to poor combustion efficiency. Hydrocarbon and soot emissions were shown to increase with the replacement ratio for all modes due to lower combustion temperatures and in-cylinder oxidation processes in the late part of heat release. Engine-out oxides of nitrogen (NOx) emissions decreased with increasing diesel replacement levels for all engine modes. A higher concentration of unburned ammonia was measured in the exhaust with increasing replacement ratios. This unburned ammonia predominantly oxidized to NOx species over the oxidation catalyst used within the TCR reactor. Ammonia substitution thus increased post-TCR reactor ammonia and NOx emissions in this work. The results show however that engine-out NH3 -to-NOx ratios were suitable for passive selective catalytic reduction thus demonstrating that both ammonia and NOx from the engine could be readily converted to N2 if the appropriate catalyst were used in the TCR reactor.
Fire Safety of Hydrogen-Fuelled Vehicles- System-Level Bonfire Test
Sep 2005
Publication
The European Community requires a vehicle-level bonfire test for vehicles using plastic fuel tanks for conventional fuels (ECE R-34 Annex 5). A similar test could be applied to hydrogen-fuelled vehicles. It would test a realistic vehicle with its complete fuel and safety systems. An advantage of such a test is that the same test could be applied independent of the hydrogen storage technology (compressed gas liquid or hydride). There are currently standards for bonfire testing of a bare Compressed Natural Gas (CNG) tank and its Pressure Relief Device (PRD). This standard is FMVSS 304 in the U.S. and ISO 15869-1 in Europe. Japan has a similar standard. It requires that a bare tank and its associated PRD be subjected to a propane flame for 20 minutes. The tank must either survive or safely vent its contents. No modern composite wound tank is expected to survive for 20 minutes – so this is not a tank test but really a PRD test. The test procedure requires the PRD to be shielded from direct impingement of the flames – but the shield is not well specified. If it shields the PRD too well the PRD will not activate and the tank will burst. This paper describes the results of a CNG and a hydrogen tank burst from such tests. The mechanical energy released is enormous. It is simply unacceptable to allow the tank to burst – the PRD and venting system must work. Organizations in the U.S Europe and Japan are in the process of modifying the CNG tank bonfire test for compressed hydrogen storage. A bare tank with a single PRD is not a good simulation of a hydrogen fuel system installed in an actual vehicle. There will usually be multiple tanks plumbed together at either the tank pressure or at the intermediate pressure (after the pressure regulator). There may be more than one PRD. The tank may be shielded (from debris) or insulated to protect it from an underbody pool fire. Also the heat transfer from the simulated pool fire (propane flame) will be very different when mounted in a vehicle versus the bare tank test. A vehicle-level pool fire test will alleviate these problems. It is therefore recommended that the bare tank test be replaced by or augmented with a vehicle-level bonfire test similar to ECE R-34 Annex 5.
Everything About Hydrogen Podcast: Why the Fuel Cell World is Different This Time
Aug 2019
Publication
The fuel cell game is not new and for many it is has been a long time coming. Few know this better than Ballard Power Systems the third ever founded Fuel Cell company that has operated since the 1970s. On the show we ask Nicolas Pocard about Ballards history and why this time the market is different for fuel cell companies.
The podcast can be found on their website
The podcast can be found on their website
Theoretical Limits of Hydrogen Storage in Metal-Organic Frameworks: Opportunities and Trade-offs
Jul 2013
Publication
Because of their high surface areas crystallinity and tunable propertiesmetal−organic frameworks (MOFs) have attracted intense interest as next-generationmaterials for gas capture and storage. While much effort has been devoted to thediscovery of new MOFs a vast catalog of existing MOFs resides within the CambridgeStructural Database (CSD) many of whose gas uptake properties have not beenassessed. Here we employ data mining and automated structure analysis to identify“cleanup” and rapidly predict the hydrogen storage properties of these compounds.Approximately 20 000 candidate compounds were generated from the CSD using analgorithm that removes solvent/guest molecules. These compounds were thencharacterized with respect to their surface area and porosity. Employing the empiricalrelationship between excess H2 uptake and surface area we predict the theoretical total hydrogen storage capacity for the subsetof ∼4000 compounds exhibiting nontrivial internal porosity. Our screening identifies several overlooked compounds having hightheoretical capacities; these compounds are suggested as targets of opportunity for additional experimental characterization.More importantly screening reveals that the relationship between gravimetric and volumetric H2 density is concave downwardwith maximal volumetric performance occurring for surface areas of 3100−4800 m2 /g. We conclude that H2 storage in MOFswill not benefit from further improvements in surface area alone. Rather discovery efforts should aim to achieve moderate massdensities and surface areas simultaneously while ensuring framework stability upon solvent removal.
CFD Modeling and Consequence Analysis of an Accidental Hydrogen Release in a Large Scale Facility
Sep 2013
Publication
In this study the consequences of an accidental release of hydrogen within large scale (>15000 m3) facilities were modelled. To model the hydrogen release an LES Navier–Stokes CFD solver called fireFoam was used to calculate the dispersion and mixing of hydrogen within a large scale facility. The performance of the CFD modelling technique was evaluated through a validation study using experimental results from a 1/6 scale hydrogen release from the literature and a grid sensitivity study. Using the model a parametric study was performed varying release rates and enclosure sizes and examining the concentrations that develop. The hydrogen dispersion results were then used to calculate the corresponding pressure loads from hydrogen-air deflagrations in the facility.
Integrated Power and Propulsion System Optimization for a Planetary-Hopping Robot
Aug 2022
Publication
Missions targeting the extreme and rugged environments on the moon and Mars have rich potential for a high science return although several risks exist in performing these exploration missions. The current generation of robots is unable to access these high-priority targets. We propose using teams of small hopping and rolling robots called SphereX that are several kilograms in mass and can be carried by a large rover or lander and tactically deployed for exploring these extreme environments. Considering that the importance of minimizing the mass and volume of these robot platforms translates into significant mission-cost savings we focus on the optimization of an integrated power and propulsion system for SphereX. Hydrogen is used as fuel for its high energy and it is stored in the form of lithium hydride and oxygen in the form of lithium perchlorate. The system design undergoes optimization using Genetic Algorithms integrated with gradient-based search techniques to find optimal solutions for a mission. Our power and propulsion system as we show in this paper is enabling because the robots can travel long distances to perform science exploration by accessing targets not possible with conventional systems. Our work includes finding the optimal mass and volume of SphereX such that it can meet end-to-end mission requirements.
Everything About Hydrogen Podcast: So, What's the Big Deal with Hydrogen?
Aug 2019
Publication
This episode is a whistle-stop tour of the hydrogen world. The team explore why hydrogen is making a resurgence as an energy carrier how decarbonising the existing hydrogen market is a huge opportunity and how fuel cells fit into the story.
The podcast can be found on their website
The podcast can be found on their website
Everything About Hydrogen Podcast: Hydrogen 101
Aug 2019
Publication
A 10-minute tour of hydrogen industry technology and terminology for those who are new to the sector or who would simply like a quick review of the basics behind this burgeoning energy source.
Podcast can be found on their website
Podcast can be found on their website
Transition to Renewable Energy for Communities: Energy Storage Requirements and Dissipation
Aug 2022
Publication
The transition of residential communities to renewable energy sources is one of the first steps for the decarbonization of the energy sector the reduction of CO2 emissions and the mitigation of global climate change. This study provides information for the development of a microgrid supplied by wind and solar energy which meets the hourly energy demand of a community of 10000 houses in the North Texas region; hydrogen is used as the energy storage medium. The results are presented for two cases: (a) when the renewable energy sources supply only the electricity demand of the community and (b) when these sources provide the electricity as well as the heating needs (for space heating and hot water) of the community. The results show that such a community can be decarbonized with combinations of wind and solar installations. The energy storage requirements are between 2.7 m3 per household and 2.2 m3 per household. There is significant dissipation in the storage–regeneration processes—close to 30% of the current annual electricity demand. The entire decarbonization (electricity and heat) of this community will result in approximately 87500 tons of CO2 emissions avoidance.
Modeling Hydrogen Refueling Infrastructure to Support Passenger Vehicles
May 2018
Publication
The year 2014 marked hydrogen fuel cell electric vehicles (FCEVs) first becoming commercially available in California where significant investments are being made to promote the adoption of alternative transportation fuels. A refueling infrastructure network that guarantees adequate coverage and expands in line with vehicle sales is required for FCEVs to be successfully adopted by private customers. In this paper we provide an overview of modelling methodologies used to project hydrogen refueling infrastructure requirements to support FCEV adoption and we describe in detail the National Renewable Energy Laboratory’s scenario evaluation and regionalization analysis (SERA) model. As an example we use SERA to explore two alternative scenarios of FCEV adoption: one in which FCEV deployment is limited to California and several major cities in the United States; and one in which FCEVs reach widespread adoption becoming a major option as passenger vehicles across the entire country. Such scenarios can provide guidance and insights for efforts required to deploy the infrastructure supporting transition toward different levels of hydrogen use as a transportation fuel for passenger vehicles in the United States.
Review of Release Behavior of Hydrogen & Natural Gas Blends from Pipelines
Aug 2021
Publication
Hydrogen can be used to reduce carbon emissions by blending into other gaseous energy carriers such as natural gas. However hydrogen blending into natural gas has important implications for safety which need to be evaluated. Hydrogen has different physical properties than natural gas and these properties affect safety evaluations concerning a leak of the blended gas. The intent of this report is to begin to investigate the safety implications of blending hydrogen into the natural gas infrastructure with respect to a leak event from a pipeline. A literature review was conducted to identify existing data that will better inform future hazard and risk assessments for hydrogen/natural gas blends. Metrics with safety implications such as heat flux and dispersion behavior may be affected by the overall blend ratio of the mixture. Of the literature reviewed there was no directly observed separation of the hydrogen from the natural gas or methane blend. No literature was identified that experimentally examined unconfined releases such as concentration fields or concentration at specific distances. Computational efforts have predicted concentration fields by modified versions of existing engineering models but the validation of these models is limited by the unavailability of literature data. There are multiple literature sources that measured flame lengths and heat flux values which are both relevant metrics to risk and hazard assessments. These data can be more directly compared to the outputs of existing engineering models for validation.
The paper can be downloaded on their website
The paper can be downloaded on their website
Advanced Optimal Planning for Microgrid Technologies Including Hydrogen and Mobility at a Real Microgrid Testbed
Apr 2021
Publication
This paper investigates the optimal planning of microgrids including the hydrogen energy system through mixed-integer linear programming model. A real case study is analyzed by extending the only microgrid lab facility in Austria. The case study considers the hydrogen production via electrolysis seasonal storage and fuelling station for meeting the hydrogen fuel demand of fuel cell vehicles busses and trucks. The optimization is performed relative to two different reference cases which satisfy the mobility demand by diesel fuel and utility electricity based hydrogen fuel production respectively. The key results indicate that the low emission hydrogen mobility framework is achieved by high share of renewable energy sources and seasonal hydrogen storage in the microgrid. The investment optimization scenarios provide at least 66% and at most 99% carbon emission savings at increased costs of 30% and 100% respectively relative to the costs of the diesel reference case (current situation)
Sector Coupling via Hydrogen to Lower the Cost of Energy System Decarbonization
Aug 2021
Publication
There is growing interest in using hydrogen (H2) as a long-duration energy storage resource in a future electric grid dominated by variable renewable energy (VRE) generation. Modeling H2 use exclusively for grid-scale energy storage often referred to as ‘‘power-to-gas-to-power (P2G2P)’’ overlooks the cost-sharing and CO2 emission benefits from using the deployed H2 assets to decarbonize other end-use sectors where direct electrification is challenging. Here we develop a generalized framework for co-optimizing infrastructure investments across the electricity and H2 supply chains accounting for the spatio-temporal variations in energy demand and supply. We apply this sector-coupling framework to the U.S. Northeast under a range of technology cost and carbon price scenarios and find greater value of power-to-H2 (P2G) vs. P2G2P routes. Specifically P2G provides grid flexibility to support VRE integration without the round-trip efficiency penalty and additional cost incurred by P2G2P routes. This form of sector coupling leads to: (a) VRE generation increase by 13–56% and (b) total system cost (and levelized costs of energy) reduction by 7–16% under deep decarbonization scenarios. Both effects increase as H2 demand for other end-uses increases more than doubling for a 97% decarbonization scenario as H2 demand quadruples. We also find that the grid flexibility enabled by sector coupling makes deployment of carbon capture and storage (CCS) for power generation less cost-effective than its use for low-carbon H2 production. These findings highlight the importance of using an integrated energy system framework with multiple energy vectors in planning cost-effective energy system decarbonization
Techno-economic Analysis of Freight Railway Electrification by Overhead Line, Hydrogen and Batteries: Case Studies in Norway and USA
Aug 2019
Publication
Two non-electrified railway lines one in Norway and the other in the USA are analysed for their potential to be electrified with overhead line equipment batteries hydrogen or hydrogen-battery hybrid powertrains. The energy requirements are established with single-train simulations including the altitude profiles of the lines air and rolling resistances and locomotive tractive-effort curves. The composition of the freight trains in terms of the number of locomotives battery wagons hydrogen wagons etc. is also calculated by the same model. The different technologies are compared by the criteria of equivalent annual costs benefit–cost ratio payback period and up-front investment based on the estimated techno-economic parameters for years 2020 2030 and 2050. The results indicate the potential of batteries and fuel cells to replace diesel on rail lines with low traffic volumes.
The Role of Hydrogen in Achieving Long Term Japanese Energy System Goals
Sep 2020
Publication
This research qualitatively reviews literature regarding energy system modeling in Japan specific to the future hydrogen economy leveraging quantitative model outcomes to establish the potential future deployment of hydrogen in Japan. The analysis focuses on the four key sectors of storage supplementing the gas grid power generation and transportation detailing the potential range of hydrogen technologies which are expected to penetrate Japanese energy markets up to 2050 and beyond. Alongside key model outcomes the appropriate policy settings governance and market mechanisms are described which underpin the potential hydrogen economy future for Japan. We find that transportation gas grid supplementation and storage end-uses may emerge in significant quantities due to policies which encourage ambitious implementation targets investment in technologies and research and development and the emergence of a future carbon pricing regime. On the other hand for Japan which will initially be dependent on imported hydrogen the cost of imports appears critical to the emergence of broad hydrogen usage particularly in the power generation sector. Further the consideration of demographics in Japan recognizing the aging shrinking population and peoples’ energy use preferences will likely be instrumental in realizing a smooth transition toward a hydrogen economy.
Research Requirements to Move the Bar Forward Using Aqueous Formate Salts as H2 Carriers for Energy Storage Applications
Nov 2020
Publication
In this perspective on hydrogen carriers we focus on the needs for the development of robust active catalysts for the release of H2 from aqueous formate solutions which are non-flammable non-toxic thermally stable and readily available at large scales at reasonable cost. Formate salts can be stockpiled in the solid state or dissolved in water for long term storage and transport using existing infrastructure. Furthermore formate salts are readily regenerated at moderate pressures using the same catalyst as for the H2 release. There have been several studies focused on increasing the activity of catalysts to release H2 at moderate temperatures i.e. < 80 °C below the operating temperature of a proton exchange membrane (PEM) fuel cell. One significant challenge to enable the use of aqueous formate salts as hydrogen carriers is the deactivation of the catalyst under operating conditions. In this work we provide a review of the most efficient heterogeneous catalysts that have been described in the literature their proposed modes of deactivation and the strategies reported to reactivate them. We discuss potential pathways that may lead to deactivation and strategies to mitigate it in a variety of H2 carrier applications. We also provide an example of a potential use case employing formate salts solutions using a fixed bed reactor for seasonal storage of energy for a microgrid application.
Hydrogen Fuel Cell Vehicles; Current Status and Future Prospect
Jun 2019
Publication
The hazardous effects of pollutants from conventional fuel vehicles have caused the scientific world to move towards environmentally friendly energy sources. Though we have various renewable energy sources the perfect one to use as an energy source for vehicles is hydrogen. Like electricity hydrogen is an energy carrier that has the ability to deliver incredible amounts of energy. Onboard hydrogen storage in vehicles is an important factor that should be considered when designing fuel cell vehicles. In this study a recent development in hydrogen fuel cell engines is reviewed to scrutinize the feasibility of using hydrogen as a major fuel in transportation systems. A fuel cell is an electrochemical device that can produce electricity by allowing chemical gases and oxidants as reactants. With anodes and electrolytes the fuel cell splits the cation and the anion in the reactant to produce electricity. Fuel cells use reactants which are not harmful to the environment and produce water as a product of the chemical reaction. As hydrogen is one of the most efficient energy carriers the fuel cell can produce direct current (DC) power to run the electric car. By integrating a hydrogen fuel cell with batteries and the control system with strategies one can produce a sustainable hybrid car
Green Synthesis of Olefin-linked Covalent Organic Frameworks for Hydrogen Fuel Cell Applications
Mar 2021
Publication
Green synthesis of crystalline porous materials for energy-related applications is of great significance but very challenging. Here we create a green strategy to fabricate a highly crystalline olefin-linked pyrazine-based covalent organic framework (COF) with high robustness and porosity under solvent-free conditions. The abundant nitrogen sites high hydrophilicity and well-defined one-dimensional nanochannels make the resulting COF an ideal platform to confine and stabilize the H3PO4 network in the pores through hydrogen-bonding interactions. The resulting material exhibits low activation energy (Ea) of 0.06 eV and ultrahigh proton conductivity across a wide relative humidity (10–90 %) and temperature range (25–80 °C). A realistic proton exchange membrane fuel cell using the olefin-linked COF as the solid electrolyte achieve a maximum power of 135 mW cm−2 and a current density of 676 mA cm−2 which exceeds all reported COF materials.
The Potential of Gas Switching Partial Oxidation Using Advanced Oxygen Carriers for Efficient H2 Production with Inherent CO2 Capture
May 2021
Publication
The hydrogen economy has received resurging interest in recent years as more countries commit to net-zero CO2 emissions around the mid-century. “Blue” hydrogen from natural gas with CO2 capture and storage (CCS) is one promising sustainable hydrogen supply option. Although conventional CO2 capture imposes a large energy penalty advanced process concepts using the chemical looping principle can produce blue hydrogen at efficiencies even exceeding the conventional steam methane reforming (SMR) process without CCS. One such configuration is gas switching reforming (GSR) which uses a Ni-based oxygen carrier material to catalyze the SMR reaction and efficiently supply the required process heat by combusting an off-gas fuel with integrated CO2 capture. The present study investigates the potential of advanced La-Fe-based oxygen carrier materials to further increase this advantage using a gas switching partial oxidation (GSPOX) process. These materials can overcome the equilibrium limitations facing conventional catalytic SMR and achieve direct hydrogen production using a water-splitting reaction. Results showed that the GSPOX process can achieve mild efficiency improvements relative to GSR in the range of 0.6–4.1%-points with the upper bound only achievable by large power and H2 co-production plants employing a highly efficient power cycle. These performance gains and the avoidance of toxicity challenges posed by Ni-based oxygen carriers create a solid case for the further development of these advanced materials. If successful results from this work indicate that GSPOX blue hydrogen plants can outperform an SMR benchmark with conventional CO2 capture by more than 10%-points both in terms of efficiency and CO2 avoidance.
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