Transmission, Distribution & Storage
Enhancing the Hydrogen Storage Properties of AxBy Intermetallic Compounds by Partial Substitution: A Short Review
Dec 2020
Publication
Solid-state hydrogen storage covers a broad range of materials praised for their gravimetric volumetric and kinetic properties as well as for the safety they confer compared to gaseous or liquid hydrogen storage methods. Among them AxBy intermetallics show outstanding performances notably for stationary storage applications. Elemental substitution whether on the A or B site of these alloys allows the effective tailoring of key properties such as gravimetric density equilibrium pressure hysteresis and cyclic stability for instance. In this review we present a brief overview of partial substitution in several AxBy alloys from the long-established AB5 and AB2-types to the recently attractive and extensively studied AB and AB3 alloys including the largely documented solid-solution alloy systems. We not only present classical and pioneering investigations but also report recent developments for each AxBy category. Special care is brought to the influence of composition engineering on desorption equilibrium pressure and hydrogen storage capacity. A simple overview of the AxBy operating conditions is provided hence giving a sense of the range of possible applications whether for low- or high-pressure systems.
The Potential of Hydrogen Hydrate as a Future Hydrogen Storage Medium
Dec 2020
Publication
Hydrogen is recognized as the “future fuel” and the most promising alternative of fossil fuels due to its remarkable properties including exceptionally high energy content per unit mass (142 MJ/kg) low mass density and massive environmental and economical upsides. A wide spectrum of methods in H2 production especially carbon-free approaches H2purification and H2storage have been investigated to bring this energy source closer to the technological deployment. Hydrogen hydrates are among the most intriguing material paradigms for H2storage due to their appealing properties such as low energy consumption for charge and discharge safety cost-effectiveness and favorable environmental features. Here we comprehensively discuss the progress in understanding of hydrogen clathrate hydrates with an emphasis on charging/discharging rate of H2 (i.e. hydrate formation and dissociation rates) and the storage capacity. A thorough understanding on phase equilibrium of the hydrates and its variation through different materials is provided. The path toward ambient temperature and pressure hydrogen batteries with high storage capacity is elucidated. We suggest that the charging rate of H2 in this storage medium and long cyclic performance are more immediate challenges than storage capacity for technological translation of this storage medium. This review and provided outlook establish a groundwork for further innovation on hydrogen hydrate systems for promising future of hydrogen fuel.
Australian Hydrogen Hubs Study
Nov 2019
Publication
Arup have conducted interviews with targeted industry and government stakeholders to gather data and perspectives to support the development of this study. Arup have also utilised private and publicly available data sources building on recent work undertaken by Geoscience Australia and Deloitte and the comprehensive stakeholder engagement process to inform our research. This study considers the supply chain and infrastructure requirements to support the development of export and domestic hubs. The study aims to provide a succinct “Hydrogen Hubs” report for presentation to the hydrogen working group.
The hydrogen supply chain infrastructure required to produce hydrogen for export and domestic hubs was identified along with feedback from the stakeholder engagement process. These infrastructure requirements can be used to determine the factors for assessing export and domestic hub opportunities. Hydrogen production pathways transportation mechanisms and uses were also further evaluated to identify how hubs can be used to balance supply and demand of hydrogen.
A preliminary list of current or anticipated locations has been developed through desktop research Arup project knowledge and the stakeholder consultation process. Over 30 potential hydrogen export locations have been identified in Australia through desktop research and the stakeholder survey and consultation process. In addition to establishing export hubs the creation of domestic demand hubs will be essential to the development of an Australian hydrogen economy. It is for this reason that a list of criteria has been developed for stakeholders to consider in the siting and design of hydrogen hubs. The key considerations explored are based on demand supply chain infrastructure and investment and policy areas.
Based on these considerations a list of criteria were developed to assess the viability of export and domestic hydrogen hubs. Criteria relevant to assessing the suitability of export and domestic hubs include:
A framework that includes the assessment criteria has been developed to aid decision making rather than recommending specific locations that would be most appropriate for a hub. This is because there are so many dynamic factors that go into selecting a location of a hydrogen hub that it is not appropriate to be overly prescriptive or prevent stakeholders from selecting the best location themselves or from the market making decisions based on its own research and knowledge. The developed framework rather provides information and support to enable these decision-making processes.
The hydrogen supply chain infrastructure required to produce hydrogen for export and domestic hubs was identified along with feedback from the stakeholder engagement process. These infrastructure requirements can be used to determine the factors for assessing export and domestic hub opportunities. Hydrogen production pathways transportation mechanisms and uses were also further evaluated to identify how hubs can be used to balance supply and demand of hydrogen.
A preliminary list of current or anticipated locations has been developed through desktop research Arup project knowledge and the stakeholder consultation process. Over 30 potential hydrogen export locations have been identified in Australia through desktop research and the stakeholder survey and consultation process. In addition to establishing export hubs the creation of domestic demand hubs will be essential to the development of an Australian hydrogen economy. It is for this reason that a list of criteria has been developed for stakeholders to consider in the siting and design of hydrogen hubs. The key considerations explored are based on demand supply chain infrastructure and investment and policy areas.
Based on these considerations a list of criteria were developed to assess the viability of export and domestic hydrogen hubs. Criteria relevant to assessing the suitability of export and domestic hubs include:
- Health and safety provisions;
- Environmental considerations;
- Economic and social considerations;
- Land availability with appropriate zoning and buffer distances & ownership (new terminals storage solar PV industries etc.);•
- Availability of gas pipeline infrastructure;
- Availability of electricity grid connectivity backup energy supply or co-location of renewables;
- Road & rail infrastructure (site access);
- Community and environmental concerns and weather. Social licence consideration;
- Berths (berthing depth ship storage loading facilities existing LNG and/or petroleum infrastructure etc.);
- Port potential (current capacity & occupancy expandability & scalability);
- Availability of or potential for skilled workers (construction & operation);
- Availability of or potential for water (recycled & desalinated);
- Opportunity for co-location with industrial ammonia production and future industrial opportunities;
- Interest (projects priority ports state development areas politics etc.);
- Shipping distance to target market (Japan & South Korea);
- Availability of demand-based infrastructure (i.e. refuelling stations).
A framework that includes the assessment criteria has been developed to aid decision making rather than recommending specific locations that would be most appropriate for a hub. This is because there are so many dynamic factors that go into selecting a location of a hydrogen hub that it is not appropriate to be overly prescriptive or prevent stakeholders from selecting the best location themselves or from the market making decisions based on its own research and knowledge. The developed framework rather provides information and support to enable these decision-making processes.
Effect of Low-Temperature Sensitization on Hydrogen Embrittlement of 301 Stainless Steel
Feb 2017
Publication
The effect of metastable austenite on the hydrogen embrittlement (HE) of cold-rolled (30% reduction in thickness) 301 stainless steel (SS) was investigated. Cold-rolled (CR) specimens were hydrogen-charged in an autoclave at 300 or 450 °C under a pressure of 10 MPa for 160 h before tensile tests. Both ordinary and notched tensile tests were performed in air to measure the tensile properties of the non-charged and charged specimens. The results indicated that cold rolling caused the transformation of austenite into α′ and ε-martensite in the 301 SS. Aging at 450 °C enhanced the precipitation of M23C6 carbides G and σ phases in the cold-rolled specimen. In addition the formation of α′ martensite and M23C6 carbides along the grain boundaries increased the HE susceptibility and low-temperature sensitization of the 450 °C-aged 301 SS. In contrast the grain boundary α′-martensite and M23C6 carbides were not observed in the as-rolled and 300 °C-aged specimens
Absence of Spillover of Hydrogen Adsorbed on Small Palladium Clusters Anchored to Graphene Vacancies
May 2021
Publication
Experimental evidence exists for the enhancement of the hydrogen storage capacity of porous carbons when these materials are doped with metal nanoparticles. One of the most studied dopants is palladium. Dissociation of the hydrogen molecules and spillover of the H atoms towards the carbon substrate has been advocated as the reason for the enhancement of the storage capacity. We have investigated this mechanism by performing ab initio density functional molecular dynamics (AIMD) simulations of the deposition of molecular hydrogen on Pd6 clusters anchored on graphene vacancies. The clusters are initially near-saturated with atomic and molecular hydrogen. This condition would facilitate the occurrence of spillover since our energy calculations based on density functional theory indicate that migration of preadsorbed H atoms towards the graphene substrate becomes exothermic on Pd clusters with high hydrogen coverages. However AIMD simulations show that the H atoms prefer to intercalate and absorb within the Pd cluster rather than migrate to the carbon substrate. These results reveal that high activation barriers exist preventing the spillover of hydrogen from the anchored Pd clusters to the carbon substrate.
Energy Management System for Hybrid PV/Wind/Battery/Fuel Cell in Microgrid-Based Hydrogen and Economical Hybrid Battery/Super Capacitor Energy Storage
Sep 2021
Publication
The present work addresses the modelling control and simulation of a microgrid integrated wind power system with Doubly Fed Induction Generator (DFIG) using a hybrid energy storage system. In order to improve the quality of the waveforms (voltages and currents) supplied to the grid instead of a two level-inverter the rotor of the DFIG is supplied using a three-level inverter. A new adaptive algorithm based on combined Direct Reactive Power Control (DRPC) and fuzzy logic controls techniques is applied to the proposed topology. In this work two topologies are proposed. In the first one the active power injected into the grid is smoothened by using an economical hybrid battery and supercapacitor energy storage system. However in the second one the excess wind energy is used to produce and store the hydrogen and then a solid oxide fuel cell system (SOFC) is utilized to regenerate electricity by using the stored hydrogen when there is not enough wind energy. To avoid overcharging deep discharging of batteries to mitigate fluctuations due to wind speed variations and to fulfil the requirement of the load profile a power management algorithm is implemented. This algorithm ensures smooth output power in the first topology and service continuity in the second. The modelling and simulation results are presented and analysed using Matlab/Simulin.
Planning, Optimisation and Evaluation of Small Power-to-Gas-to-Power Systems: Case Study of a German Dairy
May 2022
Publication
In the course of the energy transition distributed hybrid energy systems such as the combination of photovoltaic (PV) and battery storages is increasingly being used for economic and ecological reasons. However renewable electricity generation is highly volatile and storage capacity is usually limited. Nowadays a new storage component is emerging: the power-to-gas-to-power (PtGtP) technology which is able to store electricity in the form of hydrogen even over longer periods of time. Although this technology is technically well understood and developed there are hardly any evaluations and feasibility studies of its widespread integration into current distributed energy systems under realistic legal and economic market conditions. In order to be able to give such an assessment we develop a methodology and model that optimises the sizing and operation of a PtGtP system as part of a hybrid energy system under current German market conditions. The evaluation is based on a multi-criteria approach optimising for both costs and CO2 emissions. For this purpose a brute-force-based optimal design approach is used to determine optimal system sizes combined with the energy system simulation tool oemof.solph. In order to gain further insights into this technology and its future prospects a sensitivity analysis is carried out. The methodology is used to examine the case study of a German dairy and shows that PtGtP is not yet profitable but promising.
Electrochemical Conversion Technologies for Optimal Design of Decentralized Multi-energy Systems: Modeling Framework and Technology Assessment
Apr 2018
Publication
The design and operation of integrated multi-energy systems require models that adequately describe the behavior of conversion and storage technologies. Typically linear conversion performance or fixed data from technology manufacturers are employed especially for new or advanced technologies. This contribution provides a new modeling framework for electrochemical devices that bridges first-principles models to their simplified implementation in the optimization routine. First thermodynamic models are implemented to determine the on/off-design performance and dynamic behavior of different types of fuel cells and of electrolyzers. Then as such nonlinear models are intractable for use in the optimization of integrated systems different linear approximations are developed. The proposed strategies for the synthesis of reduced order models are compared to assess the impact of modeling approximations on the optimal design of multi-energy systems including fuel cells and electrolyzers. This allows to determine the most suitable level of detail for modeling the underlying electrochemical technologies from an integrated system perspective. It is found that the approximation methodology affects both the design and operation of the system with a significant effect on system costs and violation of the thermal energy demand. Finally the optimization and technology modeling framework is exploited to determine guidelines for the installation of the most suitable fuel cell technology in decentralized multi-energy systems. We show how the installation costs of PEMFC SOFC and MCFC their electrical and thermal efficiencies their conversion dynamics and the electricity price affect the system design and technology selection.
Using Additives to Control the Decomposition Temperature of Sodium Borohydride
May 2020
Publication
Hydrogen (H2) shows great promise as zero-carbon emission fuel but there are several challenges to overcome in regards to storage and transportation to make it a more universal energy solution. Gaseous hydrogen requires high pressures and large volume tanks while storage of liquid hydrogen requires cryogenic temperatures; neither option is ideal due to cost and the hazards involved. Storage in the solid state presents an attractive alternative and can meet the U.S. Department of Energy (DOE) constraints to find materials containing > 7 % H2 (gravimetric weight) with a maximum H2 release under 125 °C.
While there are many candidate hydrogen storage materials the vast majority are metal hydrides. Of the hydrides this review focuses solely on sodium borohydride (NaBH4) which is often not covered in other hydride reviews. However as it contains 10.6% (by weight) H2 that can release at 133 ± 3 JK−1mol−1 this inexpensive material has received renewed attention. NaBH4 should decompose to H2g) Na(s) and B(s) and could be recycled into its original form. Unfortunately metal to ligand charge transfer in NaBH4 induces high thermodynamic stability creating a high decomposition temperature of 530 °C. In an effort make H2 more accessible at lower temperatures researchers have incorporated additives to destabilize the structure.
This review highlights metal additives that have successfully reduced the decomposition temperature of NaBH4 with temperatures ranging from 522 °C (titanium (IV) fluoride) to 379 °C (niobium (V) fluoride). We describe synthetic methods employed chemical pathways taken and the challenges of boron derivative formation on H2 cycling. Though no trends can be found across all additives it is our hope that compiling the data here will enable researchers to gain a better understanding of the additives’ influence and to determine how a new system might be designed to make NaBH4 a more viable H2 fuel source.
While there are many candidate hydrogen storage materials the vast majority are metal hydrides. Of the hydrides this review focuses solely on sodium borohydride (NaBH4) which is often not covered in other hydride reviews. However as it contains 10.6% (by weight) H2 that can release at 133 ± 3 JK−1mol−1 this inexpensive material has received renewed attention. NaBH4 should decompose to H2g) Na(s) and B(s) and could be recycled into its original form. Unfortunately metal to ligand charge transfer in NaBH4 induces high thermodynamic stability creating a high decomposition temperature of 530 °C. In an effort make H2 more accessible at lower temperatures researchers have incorporated additives to destabilize the structure.
This review highlights metal additives that have successfully reduced the decomposition temperature of NaBH4 with temperatures ranging from 522 °C (titanium (IV) fluoride) to 379 °C (niobium (V) fluoride). We describe synthetic methods employed chemical pathways taken and the challenges of boron derivative formation on H2 cycling. Though no trends can be found across all additives it is our hope that compiling the data here will enable researchers to gain a better understanding of the additives’ influence and to determine how a new system might be designed to make NaBH4 a more viable H2 fuel source.
Adsorption-Based Hydrogen Storage in Activated Carbons and Model Carbon Structures
Jul 2021
Publication
The experimental data on hydrogen adsorption on five nanoporous activated carbons (ACs) of various origins measured over the temperature range of 303–363 K and pressures up to 20 MPa were compared with the predictions of hydrogen density in the slit-like pores of model carbon structures calculated by the Dubinin theory of volume filling of micropores. The highest amount of adsorbed hydrogen was found for the AC sample (ACS) prepared from a polymer mixture by KOH thermochemical activation characterized by a biporous structure: 11.0 mmol/g at 16 MPa and 303 K. The greatest volumetric capacity over the entire range of temperature and pressure was demonstrated by the densest carbon adsorbent prepared from silicon carbide. The calculations of hydrogen density in the slit-like model pores revealed that the optimal hydrogen storage depended on the pore size temperature and pressure. The hydrogen adsorption capacity of the model structures exceeded the US Department of Energy (DOE) target value of 6.5 wt.% starting from 200 K and 20 MPa whereas the most efficient carbon adsorbent ACS could achieve 7.5 wt.% only at extremely low temperatures. The initial differential molar isosteric heats of hydrogen adsorption in the studied activated carbons were in the range of 2.8–14 kJ/mol and varied during adsorption in a manner specific for each adsorbent.
Light-Driven Hydrogen Evolution Assisted by Covalent Organic Frameworks
Jun 2021
Publication
Covalent organic frameworks (COFs) are crystalline porous organic polymers built from covalent organic blocks that can be photochemically active when incorporating organic semiconducting units such as triazine rings or diacetylene bridges. The bandgap charge separation capacity porosity wettability and chemical stability of COFs can be tuned by properly choosing their constitutive building blocks by extension of conjugation by adjustment of the size and crystallinity of the pores and by synthetic post-functionalization. This review focuses on the recent uses of COFs as photoactive platforms for the hydrogen evolution reaction (HER) in which usually metal nanoparticles (NPs) or metallic compounds (generally Pt-based) act as co-catalysts. The most promising COF-based photocatalytic HER systems will be discussed and special emphasis will be placed on rationalizing their structure and light-harvesting properties in relation to their catalytic activity and stability under turnover conditions. Finally the aspects that need to be improved in the coming years will be discussed such as the degree of dispersibility in water the global photocatalytic efficiency and the robustness and stability of the hybrid systems putting emphasis on both the COF and the metal co-catalyst.
SimSES: A Holistic Simulation Framework for Modeling and Analyzing Stationary Energy Storage Systems
Feb 2022
Publication
The increasing feed-in of intermittent renewable energy sources into the electricity grids worldwide is currently leading to technical challenges. Stationary energy storage systems provide a cost-effective and efficient solution in order to facilitate the growing penetration of renewable energy sources. Major technical and economical challenges for energy storage systems are related to lifetime efficiency and monetary returns. Holistic simulation tools are needed in order to address these challenges before investing in energy storage systems. One of these tools is SimSES a holistic simulation framework specialized in evaluating energy storage technologies technically and economically. With a modular approach SimSES covers various topologies system components and storage technologies embedded in an energy storage application. This contribution shows the capabilities and benefits of SimSES by providing in-depth knowledge of the implementations and models. Selected functionalities are demonstrated with two use cases showing the easy-to-use simulation framework while providing detailed technical analysis for expert users. Hybrid energy storage systems consisting of lithium-ion and redox-flow batteries are investigated in a peak shaving application while various system topologies are analyzed in a frequency containment reserve application. The results for the peak shaving case study show a benefit in favor of the hybrid system in terms of overall cost and degradation behavior in applications that have a comparatively low energy throughput during lifetime. In terms of system topology a cascaded converter approach shows significant improvements in efficiency for the frequency containment reserve application.
Hydrogen-Based Energy Storage Systems for Large-Scale Data Center Applications
Nov 2021
Publication
Global demand for data and data access has spurred the rapid growth of the data center industry. To meet demands data centers must provide uninterrupted service even during the loss of primary power. Service providers seeking ways to eliminate their carbon footprint are increasingly looking to clean and sustainable energy solutions such as hydrogen technologies as alternatives to traditional backup generators. In this viewpoint a survey of the current state of data centers and hydrogen-based technologies is provided along with a discussion of the hydrogen storage and infrastructure requirements needed for large-scale backup power applications at data centers.
A Model-based Parametric and Optimal Sizing of a Battery/Hydrogen Storage of a Real Hybrid Microgrid Supplying a Residential Load: Towards Island Operation
Jun 2021
Publication
In this study the optimal sizing of a hybrid battery/hydrogen Energy Storage System “ESS” is assessed via a model-based parametric analysis in the context of a real hybrid renewable microgrid located in Huelva Spain supplying a real-time monitored residential load (3.5 kW; 5.6 MWh/year) in island mode. Four storage configurations (battery-only H2-only hybrid battery priority and hybrid H2 priority) are assessed under different Energy Management Strategies analysing system performance parameters such as Loss of Load “LL” (kWh;%) Over Production “OP” (kWh;%) round-trip storage efficiency ESS (%) and total storage cost (€) depending on the ESS sizing characteristics. A parallel approach to the storage optimal sizing via both multi-dimensional sensitivity analysis and PSO is carried out in order to address both sub-optimal and optimal regions respectively. Results show that a hybridised ESS capacity is beneficial from an energy security and efficiency point of view but can represent a substantial additional total cost (between 100 and 300 k€) to the hybrid energy system especially for the H2 ESS which presents higher costs. Reaching 100% supply from renewables is challenging and introducing a LL threshold induces a substantial relaxation of the sizing and cost requirements. Increase in battery capacity is more beneficial for the LL abatement while increasing H2 capacity is more useful to absorb large quantities of excess energy. The optimal design via PSO technique is complemented to the parametric study.
Role of Hydrogen-Charging on Nucleation and Growth of Ductile Damage in Austenitic Stainless Steels
May 2019
Publication
Hydrogen energy is a possible solution for storage in the future. The resistance of packaging materials such as stainless steels has to be guaranteed for a possible use of these materials as containers for highly pressurized hydrogen. The effect of hydrogen charging on the nucleation and growth of microdamage in two different austenitic stainless steels AISI316 and AISI316L was studied using in situ tensile tests in synchrotron X-ray tomography. Information about damage nucleation void growth and void shape were obtained. AISI316 was found to be more sensitive to hydrogen compared to AISI316L in terms of ductility loss. It was measured that void nucleation and growth are not affected by hydrogen charging. The effect of hydrogen was however found to change the morphology of nucleated voids from spherical cavities to micro-cracks being oriented perpendicular to the tensile axis.
Phase Field Modelling of Formation and Fracture of Expanding Precipitates
May 2017
Publication
It is a common belief that embedded expanding inclusions are subjected to an internal homogeneous compressive hydrostatic stress. Still cracks that appear in precipitates that occupy a larger volume than the original material are frequently observed. The appearance of cracks has since long been regarded as a paradox. In the present study it is shown that matrix materials that increases its volume even several percent during the precipitation process develop a tensile hydrostatic stress in the centre of the precipitate. This is the result of a complicated mechanical-chemical phase transformation process. The process is here studied using a Landau phase feld model. Before the material is transformed and incorporated in a precipitate it undergoes stretching beyond the elastic strain limit because of the presence of already expanded material. During the phase transformation the accompanying volumetric expansion cannot be fully accommodated which instead creates an internal compressive stress and adds tension in the surrounding material. As the growth of the precipitate proceeds a region with increasing tensile stress develops in the interior of the precipitate. This is suggested to be the most probable cause of the observed cracks. First the mechanics that lead to the tension is computed. The infuence of elastic-plastic properties is studied both for cases both with and without cracks. The growth history from microscopic to macroscopic precipitates is followed and the result is compared with observations of so called hydride blisters that are formed on surfaces of zirconium alloys in the presence of hydrogen. A common practical situation is when the zirconium is in contact with an object of lower temperature. Then the cooled spot attracts hydrogen that make the zirconium transform to a metal hydride with the shape of a blister. The simulations predicts a final size and position of the growing crack that compares well with the experimental observations.
Brittle Fracture Manifestation in Gas Pipeline Steels after Long-term Operation
Dec 2020
Publication
Gas pipelines are exposed to operational loads combined with corrosive environment action during their long-term service. Complicated service conditions lead to a worsening of steel properties a reduction of serviceability of the whole object therefore a risk of its premature failure rises. Aware of the importance of the existing problem the aim of this study is the analysis of various mechanical properties of steels after their long-term operation on gas pipelines and detecting and evaluating fractographic signs of this degradation.<br/>Mechanical properties of operated pipe steels characterizing their brittle fracture resistance were significantly decreased. Delamination areas as one of a feature of brittle fracture were identified on the fracture surfaces of specimens after SSRT of the operated steels in corrosive environment. Fracture was initiated from the outer surface of the specimens along the boundaries of ferrite and pearlite grains with significant secondary cracking.<br/>The obvious texture in the steels affects noticeably the results of the impact tests. Higher KCV values for the specimens cut in the longitudinal direction relative to the pipe axis comparing with the specimens of transversal orientation were obtained. This was explained by different length of narrow pearlite strips alternated by wide ferrite bands and interrupted by individual ferrite grains depending on the orientation of the specimen fracture surface relative to the pipe axis. Thus a proper direction of specimen cutting to achieve the maximum sensitivity of KCV parameter to operational degradation of steels is discussed. The effect of specimen orientation on the results of the Charpy testing becomes much more pronounced with steel operation. Defects accumulated in steels during their service are preferentially oriented in the pipe axial direction along the boundaries between ferrite and pearlite strips. Analyzing the fracture surfaces of the Charpy specimens after their impact testing certain signs of embrittlement were found for long term operated steels in the form of delaminations varying in size and shape and some cleavage fragments. Furthermore their percentage of total fracture surface (generally formed by dimples) correlates well with a drop in the impact toughness. The established relationship could be the basis for the introduction of fractographic criteria of the steel serviceability.
Recent Research Progress in Hybrid Photovoltaic–Regenerative Hydrogen Fuel Cell Microgrid Systems
May 2022
Publication
Hybrid photovoltaic–regenerative hydrogen fuel cell (PV-RHFC) microgrid systems are considered to have a high future potential in the effort to increase the renewable energy share in the form of solar PV technology with hydrogen generation storage and reutilization. The current study provides a comprehensive review of the recent research progress of hybrid PV-RHFC microgrid systems to extract conclusions on their characteristics and future prospects. The different components that can be integrated (PV modules electrolyzer and fuel cell stacks energy storage units power electronics and controllers) are analyzed in terms of available technology options. The main modeling and optimization methods and control strategies are discussed. Additionally various application options are provided which differentiate in terms of scale purpose and further integration with other power generating and energy storage technologies. Finally critical analysis and discussion of hybrid PV-RHFC microgrid systems were conducted based on their current status. Overall the commercialization of hybrid PV-RHFC microgrid systems requires a significant drop in the RHFC subsystem capital cost. In addition it will be necessary to produce complete hybrid PV-RHFC microgrid systems with integrated energy management control capabilities to avoid operational issues and ensure flexibility and reliability of the energy flow in relation to supply storage and demand.
A Numerical and Graphical Review of Energy Storage Technologies
Dec 2014
Publication
More effective energy production requires a greater penetration of storage technologies. This paper takes a looks at and compares the landscape of energy storage devices. Solutions across four categories of storage namely: mechanical chemical electromagnetic and thermal storage are compared on the basis of energy/power density specific energy/power efficiency lifespan cycle life self-discharge rates capital energy/power costs scale application technical maturity as well as environmental impact. It’s noted that virtually every storage technology is seeing improvements. This paper provides an overview of some of the problems with existing storage systems and identifies some key technologies that hold promise.
Research on Carbide Characteristics and Their Influence on the Properties of Welding Joints for 2.25Cr1Mo0.25V Steel
Feb 2021
Publication
The carbide characteristics of 2.25Cr1Mo0.25V steel have an extremely important influence on the mechanical properties of welding joints. In addition hydrogen resistance behavior is crucial for steel applied in hydrogenation reactors. The carbide morphology was observed by scanning electron microscopy (SEM) and the carbide microstructure was characterized by transmission electron microscopy (TEM). Tensile and impact tests were carried out and the influence of carbides on properties was studied. A hydrogen diffusion test was carried out and the hydrogen brittleness resistance of welding metal and base metal was studied by tensile testing of hydrogenated samples to evaluate the influence of hydrogen on the mechanical properties. The research results show that the strength of the welding metal was slightly higher and the Charpy impact value was significantly lower compared to the base metal. The hydrogen embrittlement resistance of the welding metal was stronger than that of the base metal. The presence of more carbides and inclusions was the main cause of the decreased impact property and hydrogen brittleness resistance of the welding metal. These conclusions have certain reference value for designing and manufacturing hydrogenation reactors. View Full-Text
Graded Grain Structure to Improve Hydrogen-Embrittlement Resistance of TWIP Steel
Nov 2020
Publication
The high strength of twinning-induced plasticity (TWIP) steels makes them vulnerable to the hydrogen embrittlement (HE) phenomenon thereby limiting their potential applications. This study suggests inducing a graded grain structure (GGS) in a Fe-17Mn-0.8C TWIP steel through shot peening and subsequent heat treatment to solve the problem. The microstructures and fracture surfaces of GGS TWIP steel were compared with those of conventionally manufactured TWIP steel possessing a uniform grain structure (UGS). Compared with the conventional UGS TWIP steel GGS steel showed similar tensile properties with a yield strength of 310 MPa tensile strength of 1060 MPa and elongation-to-failure of 135%. It also exhibited moderately enhanced low-cycle fatigue (LCF) resistance in terms of fatigue life (8196 cycles to failure) compared with the UGS steel (7201 cycles). Furthermore GGS TWIP steel exhibited a marked improvement in HE resistance both in the monotonic (by a slow-strain-rate test) and cyclic deformation modes (by the LCF test) in a hydrogen environment. A relatively fine-grained (d = 15.6 μm) surficial area enhanced the HE resistance by inhibiting hydrogen penetration and decreasing twin density while the coarse-grained (d = 74.6 μm) interior promoted the LCF resistance by suppressing crack growth
Fatigue Crack Growth in Operated Gas Pipeline Steels
Jun 2020
Publication
Regularities of fatigue crack growth for pipeline steels of different strength are presented and the changes in fatigue behavior of these steels after long term operation are analyzed. Threshold values of stress intensity factor range are lower for operated steels comparing to the corresponding values for as received ones. During the testing in the simulated soil solution NS4 a barely noticeable tendency to increase the threshold values of SIF was traced. It was explained by the appearance of intergranular fracture elements on the backgrownd of the typical flat fatigue relief already in the near-threshold region of fatigue crack growth curves in the soil solution. A higher relief of intergranular facets provided favorable conditions for occurrence of crack closure effect.<br/>Fatigue testing was performed using steel specimens after in-laboratory and in-service degradation and it was shown that results for both degraded steels are very close to each other proving the validity of the method of in-laboratory degradation. A new methodic approach to fatigue testing of pipe steels is presented which allows simulating working conditions of gas pipelines namely the hydrogen diffusion through the pipe wall to its external surface and estimating its possible effect on SCC. It consists in evaluation of the influence of hydrogen reached the crack tip only due to its diffusion on the crack growth. It is found that hydrogen absorbed by metal during the test providing such conditions causes a leap of crack growth rate in the Paris region of the fatigue crack growth curve of the tested 17H1S steel. Intergranular mechanism of fracture detected on the specimen fracture surface is suggested as a clear evidence of embrittlement of grain boundaries as a result of its hydrogenation.
Assessment of Operational Degradation of Pipeline Steels
Jun 2021
Publication
This paper summarizes a series of the authors’ research in the field of assessing the operational degradation of oil and gas transit pipeline steels. Both mechanical and electrochemical properties of steels are deteriorated after operation as is their resistance to environmentally-assisted cracking. The characteristics of resistance to brittle fracture and stress corrosion cracking decrease most intensively which is associated with a development of in-bulk dissipated microdamages of the material. The most sensitive indicators of changes in the material’s state caused by degradation are impact toughness and fracture toughness by the J-integral method. The degradation degree of pipeline steels can also be evaluated nondestructively based on in-service changes in their polarization resistance and potential of the fracture surface. Attention is drawn to hydrogenation of a pipe wall from inside as a result of the electrochemical interaction of pipe metal with condensed moisture which facilitates operational degradation of steel due to the combined action of operating stresses and hydrogen. The development of microdamages along steel texture was evidenced metallographically as a trend to the selective etching of boundaries between adjacent bands of ferrite and pearlite and fractographically by revealing brittle fracture elements on the fracture surfaces namely delamination and cleavage indicating the sites of cohesion weakening between ferrite and pearlite bands. The state of the X52 steel in its initial state and after use for 30 years was assessed based on the numerical simulation method.
A Review on the Properties of Iron Aluminide Intermetallics
Jan 2016
Publication
Iron aluminides have been among the most studied intermetallics since the 1930s when their excellent oxidation resistance was first noticed. Their low cost of production low density high strength-to-weight ratios good wear resistance ease of fabrication and resistance to high temperature oxidation and sulfurization make them very attractive as a substitute for routine stainless steel in industrial applications. Furthermore iron aluminides allow for the conservation of less accessible and expensive elements such as nickel and molybdenum. These advantages have led to the consideration of many applications such as brake disks for windmills and trucks filtration systems in refineries and fossil power plants transfer rolls for hot-rolled steel strips and ethylene crackers and air deflectors for burning high-sulfur coal. A wide application for iron aluminides in industry strictly depends on the fundamental understanding of the influence of (i) alloy composition; (ii) microstructure; and (iii) number (type) of defects on the thermo-mechanical properties. Additionally environmental degradation of the alloys consisting of hydrogen embrittlement anodic or cathodic dissolution localized corrosion and oxidation resistance in different environments should be well known. Recently some progress in the development of new micro- and nano-mechanical testing methods in addition to the fabrication techniques of micro- and nano-scaled samples has enabled scientists to resolve more clearly the effects of alloying elements environmental items and crystal structure on the deformation behavior of alloys. In this paper we will review the extensive work which has been done during the last decades to address each of the points mentioned above.
Thermoacoustic Instability Considerations for High Hydrogen Combustion in Lean Premixed Gas Turbine Combustors: A Review
Jan 2021
Publication
Hydrogen is receiving increasing attention as a versatile energy vector to help accelerate the transition to a decarbonised energy future. Gas turbines will continue to play a critical role in providing grid stability and resilience in future low-carbon power systems; however it is recognised that this role is contingent upon achieving increased thermal efficiencies and the ability to operate on carbon-neutral fuels such as hydrogen. An important consideration in the development of gas turbine combustors capable of operating with pure hydrogen or hydrogen-enriched natural gas are the significant changes in thermoacoustic instability characteristics associated with burning these fuels. This article provides a review of the effects of burning hydrogen on combustion dynamics with focus on swirl-stabilised lean-premixed combustors. Experimental and numerical evidence suggests hydrogen can have either a stabilising or destabilising impact on the dynamic state of a combustor through its influence particularly on flame structure and flame position. Other operational considerations such as the effect of elevated pressure and piloting on combustion dynamics as well as recent developments in micromix burner technology for 100% hydrogen combustion have also been discussed. The insights provided in this review will aid the development of instability mitigation strategies for high hydrogen combustion.
Effect of Hydrogen and Strain-Induced Martensite on Mechanical Properties of AISI 304 Stainless Steel
Jul 2016
Publication
Plastic deformation and strain-induced martensite (SIM α′) transformation in metastable austenitic AISI 304 stainless steel were investigated through room temperature tensile tests at strain rates ranging from 2 × 10−6 to 2 × 10−2/s. The amount of SIM was measured on the fractured tensile specimens using a feritscope and magnetic force microscope. Elongation to fracture tensile strength hardness and the amount of SIM increased with decreasing the strain rate. The strain-rate dependence of RT tensile properties was observed to be related to the amount of SIM. Specifically SIM formed during tensile tests was beneficial in increasing the elongation to fracture hardness and tensile strength. Hydrogen suppressed the SIM formation leading to hydrogen softening and localized brittle fracture.
Model of Local Hydrogen Permeability in Stainless Steel with Two Coexisting Structures
Apr 2021
Publication
The dynamics of hydrogen in metals with mixed grain structure is not well understood at a microscopic scale. One of the biggest issues facing the hydrogen economy is “hydrogen embrittlement” of metal induced by hydrogen entering and diffusing into the material. Hydrogen diffusion in metallic materials is difficult to grasp owing to the non-uniform compositions and structures of metal. Here a time-resolved “operando hydrogen microscope” was used to interpret local diffusion behaviour of hydrogen in the microstructure of a stainless steel with austenite and martensite structures. The martensite/austenite ratios differed in each local region of the sample. The path of hydrogen permeation was inferred from the time evolution of hydrogen permeation in several regions. We proposed a model of hydrogen diffusion in a dual-structure material and verified the validity of the model by simulations that took into account the transfer of hydrogen at the interfaces.
Analysis of Stress Corrosion Cracking in X80 Pipeline Steel: An Approach from the Theory of Critical Distances
Dec 2018
Publication
This paper presents an analysis of Stress Corrosion Cracking (SCC) based on the Theory of Critical Distances (TCD). The research is based on an experimental program composed of fracture specimens with notch radius varying from 0 mm (crack-like defect) up to 1 mm and tensile specimens. A pipeline steel was used in this work (X80). It has been analysed in one hydrogen embrittlement situation. The study has been completed with Finite Elements Simulation analysis. The capacity of the TCD to analyse SCC processes has been proven.
Hydrogen Embrittlement Susceptibility of Prestressing Steel Wires: The Role of the Cold-drawing Conditions
Jul 2016
Publication
Prestressing steel wires are highly susceptible to hydrogen embrittlement (HE). Residual stress-strain state produced after wire drawing plays an essential role since hydrogen damage at certain places of the material is directly affected by stress and strain fields. Changes in wire drawing conditions modify the stress and strain fields and consequently the HE susceptibility and life in service of these structural components in the presence of a hydrogenating environment. This paper analyzes the distributions of residual stress and plastic strain obtained after diverse drawing conditions (inlet die angle die bearing length varying die angle and straining path) and their influence on HE susceptibility of the wires. The conditions for industrial cold drawing can thus be optimized thereby producing commercial prestressing steel wires with improved performance against HE phenomena.
Particle Size and Crystal Phase Effects in Fischer-Tropsch Catalysts
Aug 2017
Publication
Fischer-Tropsch synthesis (FTS) is an increasingly important approach for producing liquid fuels and chemicals via syngas—that is synthesis gas a mixture of carbon monoxide and hydrogen—generated from coal natural gas or biomass. In FTS dispersed transition metal nanoparticles are used to catalyze the reactions underlying the formation of carbon-carbon bonds. Catalytic activity and selectivity are strongly correlated with the electronic and geometric structure of the nanoparticles which depend on the particle size morphology and crystallographic phase of the nanoparticles. In this article we review recent works dealing with the aspects of bulk and surface sensitivity of the FTS reaction. Understanding the different catalytic behavior in more detail as a function of these parameters may guide the design of more active selective and stable FTS catalysts.
Towards Net-zero Smart System: An Power Synergy Management Approach of Hydrogen and Battery Hybrid System with Hydrogen Safety Consideration
May 2022
Publication
The building system is one of key energy consumption sector in the market and low-carbon building will make a significant contribution for the worldwide carbon emission reduction. The multiple energy systems including renewable generations hydrogen energy and energy storage is the perspective answer to the net-zero building system. However the research gap lies in the synergy power management among the renewable flexible loads batteries and hydrogen energy systems and at the same time taking the unique characteristic of different energy sectors into account by power managing. This paper proposed the power management approach based on the game theory by which the different characteristics of the energy players are described via creating the competing relationship against net-zero emission objective so that to achieve the power synergy. Under the proposed power management method the hydrogen and battery hybrid system including the fuel cell electrolyzer and battery is designed and investigated as to unlock the power management regions and control constraints within the building system. Particularly for the hydrogen system within the hybrid system the safe and long-lifetime operation is considered respectively by high-efficiency and pressure constraints within the power management. Simulation results show that providing the same energy storage services for the building system the fuel cell with the proposed power management method sustains for 9.9 years much longer than that of equivalent consumption minimization (4.98) model predictive control (4.61) and rule-based method (7.69). Moreover the maximum tank temperature of the hydrogen tank is reduced by 3.4 K and 2.9 K compared with consumption minimization strategy and model predictive control. Also the real-time of the proposed power management is verified by a scaled-down experiment platform.
Bi-Level Planning of Grid-Forming Energy Storage–Hydrogen Storage System Considering Inertia Response and Frequency Parameter Optimization
Jul 2025
Publication
Energy storage plays an essential role in stabilizing fluctuations in renewable energy sources such as wind and solar enabling surplus electricity retention and delivering dynamic frequency regulation. However relying solely on a single form of storage often proves insufficient due to constraints in performance capacity and cost-effectiveness. To tackle frequency regulation challenges in remote desert-based renewable energy hubs— where traditional power infrastructure is unavailable—this study introduces a planning framework for an electro-hydrogen energy storage system with grid-forming capabilities designed to supply both inertia and frequency response. At the system design stage a direct current (DC) transmission network is modeled integrating battery and hydrogen storage technologies. Using this configuration the capacity settings for both grid-forming batteries and hydrogen units are optimized. This study then explores how hydrogen systems—comprising electrolyzers storage tanks and fuel cells—and grid-forming batteries contribute to inertial support. Virtual inertia models are established for each technology enabling precise estimation of the total synthetic inertia provided. At the operational level this study addresses stability concerns stemming from renewable generation variability by introducing three security indices. A joint optimization is performed for virtual inertia constants which define the virtual inertia provided by energy storage systems to assist in frequency regulation and primary frequency response parameters within the proposed storage scheme are optimized in this model. This enhances the frequency modulation potential of both systems and confirms the robustness of the proposed approach. Lastly a real-world case study involving a 13 GW renewable energy base in Northwest China connected via a ±10 GW HVDC export corridor demonstrates the practical effectiveness of the optimization strategy and system configuration.
Extreme Energetic Materials at Ultrahigh Pressures
Jul 2020
Publication
Owing to their extremely high energy density single-bonded polymeric nitrogen and atomic metallic hydrogen are generally regarded as the ultimate energetic materials. Although their syntheses normally require ultrahigh pressures of several hundred gigapascals (GPa) which prohibit direct materials application research on their stability metastability and fundamental properties are valuable for seeking extreme energetic materials through alternative synthetic routes. Various crystalline and amorphous polymeric nitrogens have been discovered between 100 and 200 GPa. Metastability at ambient conditions has been demonstrated for some of these phases. Cubic-gauche and black-phosphorus polymorphs of single-bonded nitrogen are two particularly interesting phases. Their large hystereses warrant further application-inspired basic research of nitrogen. In contrast although metallic hydrogen contains the highest-estimated energy density its picosecond lifetime and picogram quantity make its practical material application impossible at present. “Metallic hydrogen” remains a curiosity-driven basic research pursuit focusing on the pressure-induced evolution of the molecular hydrogen crystal and its electronic band structure from a low-density insulator with a very wide electronic band gap to a semiconductor with a narrow gap to a dense molecular metal and atomic metal and eventually to a previously unknown exotic state of matter. This great experimental challenge is driving relentless advancement in ultrahigh-pressure science and technology.
Is Direct Seawater Splitting Economically Meaningful?
Jun 2021
Publication
Electrocatalytic water splitting is the key process for the formation of green fuels for energy transport and storage in a sustainable energy economy. Besides electricity it requires water an aspect that seldomly has been considered until recently. As freshwater is a limited resource (<1% of earth's water) lately plentiful reports were published on direct seawater (around 96.5% of earth's water) splitting without or with additives (buffers or bases). Alternatively the seawater can be split in two steps where it is first purified by reverse osmosis and then split in a conventional water electrolyser. This quantitative analysis discusses the challenges of the direct usage of non-purified seawater. Further herein we compare the energy requirements and costs of seawater purification with those of conventional water splitting. We find that direct seawater splitting has substantial drawbacks compared to conventional water splitting and bears almost no advantage. In short it is less promising than the two-step scenario as the capital and operating costs of water purification are insignificant compared to those of electrolysis of pure water.
Analysis of Samples Cleaning Methods Prior to Hydrogen Content Determination in Steel
May 2020
Publication
There are multiple references to sample cleaning methods prior to hydrogen content determination or hydrogen spectroscopy analysis but there is still no unified criteria; different authors use their own “know-how” to perform this task. The aim of this paper is to solve or at least clarify this issue. In this work the most commonly used sample cleaning methods are compared. Then five different methodologies are applied on certified hydrogen content calibration pins and on high strength steel concrete-prestressing strands and the three main situations regarding hydrogen content in the microstructural net (non-charged charged and charged and uncharged) are studied. It was concluded that the HCl solution C-3.5 cleaning method recommended by ASTM G1 introduces large amounts of hydrogen in the samples; but can be useful for eliminating superficial oxides if necessary. The rest of the methods had similar results; but the more complete ones that involve ultrasounds and last longer than 8 min are not appropriated when important diffusion may occur on the samples during their application. Simple methods that involve acetone or trichloroethylene and last around 1 min are preferable for almost all situations as these are faster easier and cheaper. As a final recommendation as trichloroethylene is toxic the simple acetone method is in general the most convenient one for regular hydrogen content analysis.
Comparative Study of Battery Storage and Hydrogen Storage to Increase Photovoltaic Self-sufficiency in a Residential Building of Sweden
Dec 2016
Publication
Photovoltaic (PV) is promising to supply power for residential buildings. Battery is the most widely employed storage method to mitigate the intermittence of PV and to overcome the mismatch between production and load. Hydrogen storage is another promising method that it is suitable for long-term storage. This study focuses on the comparison of self-sufficiency ratio and cost performance between battery storage and hydrogen storage for a residential building in Sweden. The results show that battery storage is superior to the hydrogen storage in the studied case. Sensitivity study of the component cost within the hydrogen storage system is also carried out. Electrolyzer cost is the most sensitive factor for improving system performance. A hybrid battery and hydrogen storage system which can harness the advantages of both battery and hydrogen storages is proposed in the last place.
A Fracture Analysis of Ti-10Mo-8V-1Fe-3.5Al Alloy Screws during Assembly
Oct 2016
Publication
Titanium screws have properties that make them ideal for applications that require both a high strength-to-weight ratio and corrosion resistance such as fastener applications for aviation and aerospace. The fracture behavior of Ti-10Mo-8V-1Fe-3.5Al (TB3) alloy screws during assembly was explored. Besides visual examination other experimental techniques used for the investigation are as follows: (1) fracture characteristics and damage morphology via scanning electron microscopy (SEM); (2) chemical constituents via energy dispersive spectroscopy (EDS) and hydrogen concentration testing; (3) metallographic observation; (4) stress durability embrittlement testing; and (5) torsion simulation testing. Results show that the fracture mode of the screws is brittle. There is no obvious relation to hydrogen-induced brittle. The main reason for the fracture of titanium alloy screws is internal defects around which oxygen content is high increasing brittleness. The internal defects of screws result from grain boundary cracking caused by hot forging.
Feature of Stress Corrosion Cracking of Degraded Gas Pipeline Steels
Aug 2019
Publication
Stress corrosion cracking (SCC) of steels can reduce the structural integrity of gas pipelines. To simulate in-service degradation of pipeline steels in laboratory the method of accelerated degradation consisted in subjecting specimens to electrolytic hydrogenation to loading up the certain plastic deformation and heating of specimen at 250°C was recently developed. The purpose of this paper was to analyse mechanical and SCC behaviour of in-service and in-laboratory degraded gas pipeline steels and to reveal some fractographic features of SCC. Three pipeline steels of the different strength (17H1S which is equivalent of API X52 API X60 and API X70) were investigated. The characteristics of the as-received pipeline steels with different strength were compared with the properties of pipeline steels after in-service and in-laboratory degradation. An influence of the NS4 solution on SCC resistance of 17H1S and API X60 steels in the as-received state and after the accelerated degradation using slow strain rate tension method was analysed. The noticeable decrease of plasticity for 17H1S and API X60 steels after long-term operation was shown. Deep microdelaminations revealed in the central part of fracture surfaces for the operated steels can be considered as the signs of dissipated damaging in the metal caused by texture and hydrogen absorbed by metal. Comparison of the SCC tests results showed that the characteristics of both steels in the as-received state were insignificantly changed under the influence of the environment. At the same time the degraded steels were characterized by a high sensitivity to SCC. It was shown fractographically that it associated with cracking along interfaces of ferrite and pearlite grains with secondary deep intergranular cracks formation and also by delamination between ferrite and cementite inside pearlite grains. The similar fracture mechanism at SCC tests was revealed for near the outer surface of the specimens and in the central part of the fracture surfaces of in-laboratory degraded specimens. These results demonstrated the key role of hydrogen during SCC and in-bulk cracking as well.
Complex Methods of Estimation Technological Strength of Welded Joints in Welding at Low Temperatures
Feb 2021
Publication
A comprehensive methodology for estimating the technological strength of welded joints are developed based on parameters reflecting the welding technology weldability hydrogen force and deformation conditions for welding and other informative parameters that correlate with the characteristics of the welded joint as well as improving existing methods for estimating the technological strength of welded joints connections through the introduction of modern equipment and non-destructive testing systems. It has been established that the proposed comprehensive estimation methodology will allow reaching a new qualitative level in assessing the technological strength of a welded joint using modern equipment and measuring instruments. According to the results of the experimental work it was found that when welding at low temperatures the increase in the probability of the formation and development of cold cracks is mainly determined by the critical content of diffusible hydrogen in the weld metal depending on the structural and force parameters of the welded joints.
Carbon Capture, Usage and Storage: An Update on Business Models for Carbon Capture, Usage and Storage
Dec 2020
Publication
An update on the proposed commercial frameworks for transport and storage power and industrial carbon capture business models.
Materials for End to End Hydrogen Roadmap
Jun 2021
Publication
This report is commissioned by the Henry Royce Institute for advanced materials as part of its role around convening and supporting the UK advanced materials community to help promote and develop new research activity. The overriding objective is to bring together the advanced materials community to discuss analyse and assimilate opportunities for emerging materials research for economic and societal benefit. Such research is ultimately linked to both national and global drivers namely Transition to Zero Carbon Sustainable Manufacture Digital & Communications Circular Economy as well as Health & Wellbeing.
This paper can be download from their website
This paper can be download from their website
Hydrogen in the Gas Distribution Networks: A Kickstart Project as an Input into the Development of a National Hydrogen Strategy for Australia
Nov 2019
Publication
The report investigates a kickstart project that allows up to 10% hydrogen into gas distribution networks. It reviews the technical impacts and standards to identify barriers and develop recommendations.
You can see the full report on the Australian Government website here
This report is developed in support of Australia's National Hydrogen Strategy
You can see the full report on the Australian Government website here
This report is developed in support of Australia's National Hydrogen Strategy
Effect of α′ Martensite Content Induced by Tensile Plastic Prestrain on Hydrogen Transport and Hydrogen Embrittlement of 304L Austenitic Stainless Steel
Aug 2018
Publication
Effects of microstructural changes induced by prestraining on hydrogen transport and hydrogen embrittlement (HE) of austenitic stainless steels were studied by hydrogen precharging and tensile testing. Prestrains higher than 20% at 20 °C significantly enhance the HE of 304L steel as they induce severe α′ martensite transformation accelerating hydrogen transport and hydrogen entry during subsequent hydrogen exposure. In contrast 304L steel prestrained at 50 and 80 °C and 316L steel prestrained at 20 °C exhibit less HE due to less α′ after prestraining. The increase of dislocations after prestraining has a negligible influence on apparent hydrogen diffusivity compared with pre-existing α′. The deformation twins in heavily prestrained 304L steel can modify HE mechanism by assisting intergranular (IG) fracture. Regardless of temperature and prestrain level HE and apparent diffusivity ( Dapp ) increase monotonously with α′ volume fraction ( fα′ ). Dapp can be described as log Dapp=log(Dα′sα′/sγ)+log[fα′/(1−fα′)] for 10%<fα′<90% with Dα′ is diffusivity in α′ sα′ and sγ are solubility in α′ and austenite respectively. The two equations can also be applied to these more typical duplex materials containing both BCC and FCC phases.
Mechanical Properties and Hydrogen Embrittlement of Laser-Surface Melted AISI 430 Ferritic Stainless Steel
Feb 2020
Publication
Hydrogen was doped in austenitic stainless steel (ASS) 316L tensile samples produced by the laser-powder bed fusion (L-PBF) technique. For this aim an electrochemical method was conducted under a high current density of 100 mA/cm2 for three days to examine its sustainability under extreme hydrogen environments at ambient temperatures. The chemical composition of the starting powders contained a high amount of Ni approximately 12.9 wt.% as a strong austenite stabilizer. The tensile tests disclosed that hydrogen charging caused a minor reduction in the elongation to failure (approximately 3.5% on average) and ultimate tensile strength (UTS; approximately 2.1% on average) of the samples using a low strain rate of 1.2 × 10−4 s−1. It was also found that an increase in the strain rate from 1.2 × 10−4 s−1 to 4.8 × 10−4 s−1 led to a reduction of approximately 3.6% on average for the elongation to failure and 1.7% on average for UTS in the pre-charged samples. No trace of martensite was detected in the X-ray diffraction (XRD) analysis of the fractured samples thanks to the high Ni content which caused a minor reduction in UTS × uniform elongation (UE) (GPa%) after the H charging. Considerable surface tearing was observed for the pre-charged sample after the tensile deformation. Additionally some cracks were observed to be independent of the melt pool boundaries indicating that such boundaries cannot necessarily act as a suitable area for the crack propagation.
Property Optimization in As-Quenched Martensitic Steel by Molybdenum and Niobium Alloying
Apr 2018
Publication
Niobium microalloying is the backbone of modern low-carbon high strength low alloy (HSLA) steel metallurgy providing a favorable combination of strength and toughness by pronounced microstructural refinement. Molybdenum alloying is established in medium-carbon quenching and tempering of steel by delivering high hardenability and good tempering resistance. Recent developments of ultra-high strength steel grades such as fully martensitic steel can be optimized by using beneficial metallurgical effects of niobium and molybdenum. The paper details the metallurgical principles of both elements in such steel and the achievable improvement of properties. Particularly the underlying mechanisms of improving toughness and reducing the sensitivity towards hydrogen embrittlement by a suitable combination of molybdenum and niobium alloying will be discussed.
On the Concept of Micro-fracture Map (MFM) and its Role in Structural Integrity Evaluations in Materials Science and Engineering: A Tribute to Jorge Manrique
Dec 2020
Publication
This paper deals with the concept of micro-fracture map (MFM) and its role in structural integrity evaluations in materials science and engineering on the basis of previous research by the author on notch-induced fracture and hydrogen embrittlement of progressively cold drawn pearlitic steels and 316L austenitic stainless steel. With regard to this some examples are provided of assembly of MFMs in particular situations.
The Effect of Heat Treatments on the Constituent Materials of a Nuclear Reactor Pressure Vessel in Hydrogen Environment
Jul 2016
Publication
A nuclear reactor pressure vessel (NRPV) wall is formed by two layer of different materials: an inner layer of stainless steel (cladding material) and an outer layer of low carbon steel (base material) which is highly susceptible to corrosion related phenomena. A reduction of the mechanical properties of both materials forming the wall would appear due to the action of the harsh environment causing hydrogen embrittlement (HE) related phenomena. As a result of the manufacturing process residual stresses and strains appear in the NRPV wall thereby influencing the main stage in HE: hydrogen diffusion. A common engineering practice for reducing such states is to apply a tempering heat treatment. In this paper a numerical analysis is carried out for revealing the influence of the heat treatment parameters (tempering temperature and tempering time) on the HE of a commonly used NRPV. To achieve this goal a numerical model of hydrogen diffusion assisted by stress and strain was used considering diverse residual stress-strain states after tempering. This way the obtained hydrogen accumulation during operation time of the NRPV provides insight into the better tempering conditions from the structural integrity point of view.
Recent Progress Using Solid-State Materials for Hydrogen Storage: A Short Review
Feb 2022
Publication
With the rapid growth in demand for effective and renewable energy the hydrogen era has begun. To meet commercial requirements efficient hydrogen storage techniques are required. So far four techniques have been suggested for hydrogen storage: compressed storage hydrogen liquefaction chemical absorption and physical adsorption. Currently high-pressure compressed tanks are used in the industry; however certain limitations such as high costs safety concerns undesirable amounts of occupied space and low storage capacities are still challenges. Physical hydrogen adsorption is one of the most promising techniques; it uses porous adsorbents which have material benefits such as low costs high storage densities and fast charging–discharging kinetics. During adsorption on material surfaces hydrogen molecules weakly adsorb at the surface of adsorbents via long-range dispersion forces. The largest challenge in the hydrogen era is the development of progressive materials for efficient hydrogen storage. In designing efficient adsorbents understanding interfacial interactions between hydrogen molecules and porous material surfaces is important. In this review we briefly summarize a hydrogen storage technique based on US DOE classifications and examine hydrogen storage targets for feasible commercialization. We also address recent trends in the development of hydrogen storage materials. Lastly we propose spillover mechanisms for efficient hydrogen storage using solid-state adsorbents.
Corrosion Mechanisms of High-Mn Twinning-Induced Plasticity (TWIP) Steels: A Critical Review
Feb 2021
Publication
Twinning-induced plasticity (TWIP) steels have higher strength and ductility than conventional steels. Deformation mechanisms producing twins that prevent gliding and stacking of dislocations cause a higher ductility than that of steel grades with the same strength. TWIP steels are considered to be within the new generation of advanced high-strength steels (AHSS). However some aspects such as the corrosion resistance and performance in service of TWIP steel materials need more research. Application of TWIP steels in the automotive industry requires a proper investigation of corrosion behavior and corrosion mechanisms which would indicate the optimum degree of protection and the possible decrease in costs. In general Fe−Mn-based TWIP steel alloys can passivate in oxidizing acid neutral and basic solutions however they cannot passivate in reducing acid or active chloride solutions. TWIP steels have become as a potential material of interest for automotive applications due to their effectiveness impact resistance and negligible harm to the environment. The mechanical and corrosion performance of TWIP steels is subjected to the manufacturing and processing steps like forging and casting elemental composition and thermo-mechanical treatment. Corrosion of TWIP steels caused by both intrinsic and extrinsic factors has posed a serious problem for their use. Passivity breakdown caused by pitting and galvanic corrosion due to phase segregation are widely described and their critical mechanisms examined. Numerous studies have been performed to study corrosion behaviour and passivation of TWIP steel. Despite the large number of articles on corrosion few comprehensive reports have been published on this topic. The current trend for development of corrosion resistance TWIP steel is thoroughly studied and represented showing the key mechanisms and factors influencing corrosion processes and its consequences on TWIP steel. In addition suggestions for future works and gaps in the literature are considered.
Evaluation of Blistered and Cold Deformed ULC Steel with Melt Extraction and Thermal Desorption Spectroscopy
Dec 2019
Publication
Hydrogen characterization techniques like melt extraction and thermal desorption spectroscopy (TDS) are useful tools in order to evaluate and understand the interaction between hydrogen and metals. These two techniques are used here on cold deformed ultra-low carbon (ULC) steel with and without hydrogen induced damage. The material is charged electrochemically in order to induce varying amounts of hydrogen and variable degrees of hydrogen induced damage. The aim of this work is to evaluate to which extent the hydrogen induced damage would manifest itself in melt extraction and TDS measurements.
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