Transmission, Distribution & Storage
Quantitative Evaluations of Hydrogen Diffusivity in V-X (X = Cr, Al, Pd) Alloy Membranes Based on Hydrogen Chemical Potential
Jan 2021
Publication
Vanadium (V) has higher hydrogen permeability than Pd-based alloy membranes but exhibits poor resistance to hydrogen-induced embrittlement. The alloy elements are added to reduce hydrogen solubility and prevent hydrogen-induced embrittlement. To enhance hydrogen permeability the alloy elements which improve hydrogen diffusivity in V are more suitable. In the present study hydrogen diffusivity in V-Cr V-Al and V-Pd alloy membranes was investigated in view of the hydrogen chemical potential and compared with the previously reported results of V-Fe alloy membranes. The additions of Cr and Fe to V improved the mobility of hydrogen atoms. In contrast those of Al and Pd decreased hydrogen diffusivity. The first principle calculations revealed that the hydrogen atoms cannot occupy the first-nearest neighbour T sites (T1 sites) of Al and Pd in the V crystal lattice. These blocking effects will be a dominant contributor to decreasing hydrogen diffusivity by the additions of Al and Pd. For V-based alloy membranes Fe and Cr are more suitable alloy elements compared with Al and Pd in view of hydrogen diffusivity.
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.
Commercialisation of Energy Storage
Mar 2015
Publication
This report was created to ensure a deeper understanding of the role and commercial viability of energy storage in enabling increasing levels of intermittent renewable power generation. It was specifically written to inform thought leaders and decision-makers about the potential contribution of storage in order to integrate renewable energy sources (RES) and about the actions required to ensure that storage is allowed to compete with the other flexibility options on a level playing field.<br/>The share of RES in the European electric power generation mix is expected to grow considerably constituting a significant contribution to the European Commission’s challenging targets to reduce greenhouse gas emissions. The share of RES production in electricity demand should reach about 36% by 2020 45-60% by 2030 and over 80% in 2050.<br/>In some scenarios up to 65% of EU power generation will be covered by solar photovoltaics (PV) as well as on- and offshore wind (variable renewable energy (VRE) sources) whose production is subject to both seasonal as well as hourly weather variability. This is a situation the power system has not coped with before. System flexibility needs which have historically been driven by variable demand patterns will increasingly be driven by supply variability as VRE penetration increases to very high levels (50% and more).<br/>Significant amounts of excess renewable energy (on the order of TWh) will start to emerge in countries across the EU with surpluses characterized by periods of high power output (GW) far in excess of demand. These periods will alternate with times when solar PV and wind are only generating at a fraction of their capacity and non-renewable generation capacity will be required.<br/>In addition the large intermittent power flows will put strain on the transmission and distribution network and make it more challenging to ensure that the electricity supply matches demand at all times.<br/>New systems and tools are required to ensure that this renewable energy is integrated into the power system effectively. There are four main options for providing the required flexibility to the power system: dispatchable generation transmission and distribution expansion demand side management and energy storage. All of these options have limitations and costs and none of them can solve the RES integration challenge alone. This report focuses on the question to what extent current and new storage technologies can contribute to integrate renewables in the long run and play additional roles in the short term.
Quantitative Risk Analysis of a Hazardous Jet Fire Event for Hydrogen Transport in Natural Gas Transmission Pipelines
Jan 2021
Publication
With the advent of large-scale application of hydrogen transportation becomes crucial. Reusing the existing natural gas transmission system could serve as catalyst for the future hydrogen economy. However a risk analysis of hydrogen transmission in existing pipelines is essential for the deployment of the new energy carrier. This paper focuses on the individual risk (IR) associated with a hazardous hydrogen jet fire and compares it with the natural gas case. The risk analysis adopts a detailed flame model and state of the art computational software to provide an enhanced physical description of flame characteristics.<br/>This analysis concludes that hydrogen jet fires yield lower lethality levels that decrease faster with distance than natural gas jet fires. Consequently for large pipelines hydrogen transmission is accompanied by significant lower IR. Howbeit ignition effects increasingly dominate the IR for decreasing pipeline diameters and cause hydrogen transmission to yield increased IR in the vicinity of the pipeline when compared to natural gas.
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.
Materials Towards Carbon-free, Emission-free and Oil-free Mobility: Hydrogen Fuel-cell Vehicles—Now and in the Future
Jul 2010
Publication
In the past material innovation has changed society through new material-induced technologies adding a new value to society. In the present world engineers and scientists are expected to invent new materials to solve the global problem of climate change. For the transport sector the challenge for material engineers is to change the oil-based world into a sustainable world. After witnessing the recent high oil price and its adverse impact on the global economy it is time to accelerate our efforts towards this change.
Industries are tackling global energy issues such as oil and CO2 as well as local environmental problems such as NOx and particulate matter. Hydrogen is the most promising candidate to provide carbon-free emission-free and oil-free mobility. As such engineers are working very hard to bring this technology into the real society. This paper describes recent progress of vehicle technologies as well as hydrogen-storage technologies to extend the cruise range and ensure the easiness of refuelling and requesting material scientists to collaborate with industry to fight against global warming.
Link to document download on Royal Society Website
Industries are tackling global energy issues such as oil and CO2 as well as local environmental problems such as NOx and particulate matter. Hydrogen is the most promising candidate to provide carbon-free emission-free and oil-free mobility. As such engineers are working very hard to bring this technology into the real society. This paper describes recent progress of vehicle technologies as well as hydrogen-storage technologies to extend the cruise range and ensure the easiness of refuelling and requesting material scientists to collaborate with industry to fight against global warming.
Link to document download on Royal Society Website
Rock Mass Response for Lined Rock Caverns Subjected to High Internal Gas Pressure
Mar 2022
Publication
The storage of hydrogen gas in underground lined rock caverns (LRCs) enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel. Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur. Analytical and numerical models can be used to estimate the rock mass response to high internal pressure; however the fitness of these models under different in situ stress conditions and cavern shapes has not been studied. In this paper the suitability of analytical and numerical models to estimate the maximum cavern wall tangential strain under high internal pressure is studied. The analytical model is derived in detail and finite element (FE) models considering both two-dimensional (2D) and three-dimensional (3D) geometries are presented. These models are verified with field measurements from the LRC in Skallen southwestern Sweden. The analytical model is inexpensive to implement and gives good results for isotropic in situ stress conditions and large cavern heights. For the case of anisotropic horizontal in situ stresses as the conditions in Skallen the 3D FE model is the best approach
Investigation of Hydrogen Embrittlement Susceptibility and Fracture Toughness Drop after in situ Hydrogen Cathodic Charging for an X65 Pipeline Steel
Apr 2020
Publication
The present research focuses on the investigation of an in situ hydrogen charging effect during Crack Tip Opening Displacement testing (CTOD) on the fracture toughness properties of X65 pipeline steel. This grade of steel belongs to the broader category of High Strength Low Alloy Steels (HSLA) and its microstructure consists of equiaxed ferritic and bainitic grains with a low volume fraction of degenerated pearlite islands. The studied X65 steel specimens were extracted from pipes with 19.15 mm wall thickness. The fracture toughness parameters were determined after imposing the fatigue pre-cracked specimens on air on a specific electrolytic cell under a slow strain rate bending loading (according to ASTM G147-98 BS7448 and ISO12135 standards). Concerning the results of this study in the first phase the hydrogen cations’ penetration depth the diffusion coefficient of molecular and atomic hydrogen and the surficial density of blisters were determined. Next the characteristic parameters related to fracture toughness (such as J KQ CTODel CTODpl) were calculated by the aid of the Force-Crack Mouth Open Displacement curves and the relevant analytical equations.
The Influence of Refractory Metals on the Hydrogen Storage Characteristics of FeTi-based Alloys Prepared by Suspended Droplet Alloying
Jun 2020
Publication
The influence of the addition of refractory metals (molybdenum and tantalum) on the hydrogenation properties of FeTi intermetallic phase-based alloys was investigated. The suspended droplet alloying technique was applied to fabricate FeTiTa-based and FeTiMo-based alloys. The phase composition and hydrogen storage properties of the samples were investigated. The samples modified with the refractory metals exhibited lower plateau pressures and lower hydrogen storage capacities than those of the FeTi reference sample due to solid solution formation. It was observed that the equilibrium pressures decreased with the amount of molybdenum which is in good agreement with the increase in the cell parameters of the TiFe phase. Suspended droplet alloying was found to be a practical method to fabricate alloys with refractory metal additions; however it is appropriate for screening samples with desired chemical and phase compositions rather than for manufacturing purposes.
Seasonal and Multi-Seasonal Energy Storage by Power-to-Methane Technology
Jun 2021
Publication
The time-range of applicability of various energy-storage technologies are limited by self-discharge and other inevitable losses. While batteries and hydrogen are useful for storage in a time-span ranging from hours to several days or even weeks for seasonal or multi-seasonal storage only some traditional and quite costly methods can be used (like pumped-storage plants Compressed Air Energy Storage or energy tower). In this paper we aim to show that while the efficiency of energy recovery of Power-to-Methane technology is lower than for several other methods due to the low self-discharge and negligible standby losses it can be a suitable and cost-effective solution for seasonal and multi-seasonal energy storage.
The Effect of Graphite Size on Hydrogen Absorption and Tensile Properties of Ferritic Ductile Cast Iron
Jun 2019
Publication
Ductile cast iron (DCI) is one of prospective materials used for the hydrogen equipment because of low-cost good workability and formability. The wide range of mechanical properties of DCI is obtained by controlling microstructural factors such as graphite size volume fraction of graphite matrix structure and so on. Therefore it is important to find out an optimal microstructural condition that is less susceptible to hydrogen embrittlement. In this study the effects of graphite size on the hydrogen absorption capability and the hydrogen-induced ductility loss of ferritic DCI were investigated.<br/>Several kinds of ferritic DCIs with a different graphite diameter of about 10 µm - 30 µm were used for the tensile test and the hydrogen content measurement. Hydrogen charging was performed prior to the tensile test by exposing a specimen to high-pressure hydrogen gas. Then the tensile test was performed in air at room temperature. The hydrogen content of a specimen was measured by a thermal desorption analyzer.<br/>It was found that the amount of hydrogen stored in DCI was dependent on the graphite size. As the graphite diameter increased the hydrogen content sharply increased at a certain graphite diameter and then it became nearly constant irrespective of increase in graphite diameter. In other words there was the critical graphite diameter that significantly changed the hydrogen absorption capability. The ductility was decreased by hydrogen and the hydrogen-induced ductility loss was dependent on the hydrogen content. Therefore the hydrogen embrittlement of DCI became remarkable when the graphite size was larger than the critical value.
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.
Unusual Hydrogen Implanted Gold with Lattice Contraction at Increased Hydrogen Content
Mar 2021
Publication
The experimental evidence for the contraction of volume of gold implanted with hydrogen at low doses is presented. The contraction of lattice upon the addition of other elements is very rare and extraordinary in the solid-state not only for gold but also for many other solids. To explain the underlying physics the pure kinetic theory of absorption is not adequate and the detailed interaction of hydrogen in the lattice needs to be clarified. Our analysis points to the importance of the formation of hydride bonds in a dynamic manner and explains why these bonds become weak at higher doses leading to the inverse process of volume expansion frequently seen in metallic hydrogen containers.
Hydrogen Embrittlement of Steel Pipelines During Transients
May 2021
Publication
Blending hydrogen into natural gas pipelines is a recent alternative adopted for hydrogen transportation as a mixture with natural gas. In this paper hydrogen embrittlement of steel pipelines originally designed for natural gas transportation is investigated. Solubility permeation and diffusion phenomena of hydrogen molecules into the crystalline lattice structure of the pipeline material are followed up based on transient evolution of internal pressure applied on the pipeline wall. The transient regime is created through changes of gas demand depending on daily consumptions. As a result the pressure may reach excessive values that lead to the acceleration of hydrogen solubility and its diffusion through the pipeline wall. Furthermore permeation is an important parameter to determine the diffusion amount of hydrogen inside the pipeline wall resulting in the embrittlement of the material. The numerical obtained results have shown that using pipelines designed for natural gas conduction to transport hydrogen is a risky choice. Actually added to overpressure and great fluctuations during transients that may cause fatigue and damage the structure also the latter pressure evolution is likely to induce the diffusion phenomena of hydrogen molecules into the lattice of the structure leading to brittle the pipe material. The numerical simulation reposes on solving partial differential equations describing transient gas flow in pipelines coupled with the diffusion equation for mass transfer. The model is built using the finite elements based software COMSOL Multiphysics considering different cases of pipe material; API X52 (base metal and nutrided) and API X80 steels. Obtained results allowed tracking the evolution with time of hydrogen concentration through the pipeline internal wall based on the pressure variation due to transient gas flow. Such observation permits to estimate the amount of hydrogen diffused in the metal to avoid leakage of this flammable gas. Thus precautions may be taken to prevent explosive risks due to hydrogen embrittlement of steel pipelines among other effects that can lead to alter safe conditions of gas conduction.
A Review of Recent Advances on the Effects of Microstructural Refinement and Nano-Catalytic Additives on the Hydrogen Storage Properties of Metal and Complex Hydrides
Dec 2010
Publication
The recent advances on the effects of microstructural refinement and various nano-catalytic additives on the hydrogen storage properties of metal and complex hydrides obtained in the last few years in the allied laboratories at the University of Waterloo (Canada) and Military University of Technology (Warsaw Poland) are critically reviewed in this paper. The research results indicate that microstructural refinement (particle and grain size) induced by ball milling influences quite modestly the hydrogen storage properties of simple metal and complex metal hydrides. On the other hand the addition of nanometric elemental metals acting as potent catalysts and/or metal halide catalytic precursors brings about profound improvements in the hydrogen absorption/desorption kinetics for simple metal and complex metal hydrides alike. In general catalytic precursors react with the hydride matrix forming a metal salt and free nanometric or amorphous elemental metals/intermetallics which in turn act catalytically. However these catalysts change only kinetic properties i.e. the hydrogen absorption/desorption rate but they do not change thermodynamics (e.g. enthalpy change of hydrogen sorption reactions). It is shown that a complex metal hydride LiAlH4 after high energy ball milling with a nanometric Ni metal catalyst and/or MnCl2 catalytic precursor is able to desorb relatively large quantities of hydrogen at RT 40 and 80 °C. This kind of behavior is very encouraging for the future development of solid state hydrogen systems.
Charpy Impact Properties of Hydrogen-Exposed 316L Stainless Steel at Ambient and Cryogenic Temperatures
May 2019
Publication
316L stainless steel is a promising material candidate for a hydrogen containment system. However when in contact with hydrogen the material could be degraded by hydrogen embrittlement (HE). Moreover the mechanism and the effect of HE on 316L stainless steel have not been clearly studied. This study investigated the effect of hydrogen exposure on the impact toughness of 316L stainless steel to understand the relation between hydrogen charging time and fracture toughness at ambient and cryogenic temperatures. In this study 316L stainless steel specimens were exposed to hydrogen in different durations. Charpy V-notch (CVN) impact tests were conducted at ambient and low temperatures to study the effect of HE on the impact properties and fracture toughness of 316L stainless steel under the tested temperatures. Hydrogen analysis and scanning electron microscopy (SEM) were conducted to find the effect of charging time on the hydrogen concentration and surface morphology respectively. The result indicated that exposure to hydrogen decreased the absorbed energy and ductility of 316L stainless steel at all tested temperatures but not much difference was found among the pre-charging times. Another academic insight is that low temperatures diminished the absorbed energy by lowering the ductility of 316L stainless steel
Large-scale Storage of Hydrogen
Mar 2019
Publication
The large-scale storage of hydrogen plays a fundamental role in a potential future hydrogen economy. Although the storage of gaseous hydrogen in salt caverns already is used on a full industrial scale the approach is not applicable in all regions due to varying geological conditions. Therefore other storage methods are necessary. In this article options for the large-scale storage of hydrogen are reviewed and compared based on fundamental thermodynamic and engineering aspects. The application of certain storage technologies such as liquid hydrogen methanol ammonia and dibenzyltoluene is found to be advantageous in terms of storage density cost of storage and safety. The variable costs for these high-density storage technologies are largely associated with a high electricity demand for the storage process or with a high heat demand for the hydrogen release process. If hydrogen is produced via electrolysis and stored during times of low electricity prices in an industrial setting these variable costs may be tolerable.
Modifications in the Composition of CuO/ZnO/Al2O3 Catalyst for the Synthesis of Methanol by CO2 Hydrogenation
Jun 2021
Publication
Renewable methanol obtained from CO2 and hydrogen provided from renewable energy was proposed to close the CO2 loop. In industry methanol synthesis using the catalyst CuO/ZnO/Al2O3 occurs at a high pressure. We intend to make certain modification on the traditional catalyst to work at lower pressure maintaining high selectivity. Therefore three heterogeneous catalysts were synthesized by coprecipitation to improve the activity and the selectivity to methanol under mild conditions of temperature and pressure. Certain modifications on the traditional catalyst Cu/Zn/Al2O3 were employed such as the modification of the synthesis time and the addition of Pd as a dopant agent. The most efficient catalyst among those tested was a palladium-doped catalyst 5% Pd/Cu/Zn/Al2O3. This had a selectivity of 64% at 210 °C and 5 bar.
Research Progress of Cryogenic Materials for Storage and Transportation of Liquid Hydrogen
Jul 2021
Publication
Liquid hydrogen is the main fuel of large-scale low-temperature heavy-duty rockets and has become the key direction of energy development in China in recent years. As an important application carrier in the large-scale storage and transportation of liquid hydrogen liquid hydrogen cryogenic storage and transportation containers are the key equipment related to the national defense security of China’s aerospace and energy fields. Due to the low temperature of liquid hydrogen (20 K) special requirements have been put forward for the selection of materials for storage and transportation containers including the adaptability of materials in a liquid hydrogen environment hydrogen embrittlement characteristics mechanical properties and thermophysical properties of liquid hydrogen temperature which can all affect the safe and reliable design of storage and transportation containers. Therefore it is of great practical significance to systematically master the types and properties of cryogenic materials for the development of liquid hydrogen storage and transportation containers. With the wide application of liquid hydrogen in different occasions the requirements for storage and transportation container materials are not the same. In this paper the types and applications of cryogenic materials commonly used in liquid hydrogen storage and transportation containers are reviewed. The effects of low-temperature on the mechanical properties of different materials are introduced. The research progress of cryogenic materials and low-temperature performance data of materials is introduced. The shortcomings in the research and application of cryogenic materials for liquid hydrogen storage and transportation containers are summarized to provide guidance for the future development of container materials. Among them stainless steel is the most widely used cryogenic material for liquid hydrogen storage and transportation vessel but different grades of stainless steel also have different applications which usually need to be comprehensively considered in combination with its low temperature performance corrosion resistance welding performance and other aspects. However with the increasing demand for space liquid hydrogen storage and transportation the research on high specific strength cryogenic materials such as aluminum alloy titanium alloy or composite materials is also developing. Aluminum alloy liquid hydrogen storage and transportation containers are widely used in the space field while composite materials have significant advantages in being lightweight. Hydrogen permeation is the key bottleneck of composite storage and transportation containers. At present there are still many technical problems that have not been solved.
Micro and Macro Mechanical Analysis of Gas Pipeline Steels
Sep 2017
Publication
The actual safety margins of gas pipelines depend on a number of factors that include the mechanical characteristics of the material. The evolution with time of the metal properties can be evaluated by mechanical tests performed at different scales seeking for the best compromise between the simplicity of the experimental setup to be potentially employed in situ and the reliability of the results. Possible alternatives are comparatively assessed on pipeline steels of different compositions and in different states.
Power to Hydrogen and Power to Water Using Wind Energy
May 2022
Publication
The need for energy and water security on islands has led to an increase in the use of wind power. However the intermittent nature of wind generation means it needs to be coupled with a storage system. Motivated by this two different models of surplus energy storage systems are investigated in this paper. In both models renewable wind energy is provided by a wind farm. In the first model a pumped hydro storage system (PHS) is used for surplus energy storage while in the second scenario a hybrid pumped hydrogen storage system (HPHS) is applied consisting of a PHS and a hydrogen storage system. The goal of this study is to compare the single and the hybrid storage system to fulfill the energy requirements of the island’s electricity load and desalination demands for domestic and irrigation water. The cost of energy (COE) is 0.287 EUR/kWh for PHS and 0.360 EUR/kWh for HPHS while the loss of load probability (LOLP) is 22.65% for PHS and 19.47% for HPHS. Sensitivity analysis shows that wind speed is the key parameter that most affects COE cost of water (COW) and LOLP indices while temperature affects the results the least.
A Perspective on Hydrogen Investment, Deployment and Cost Competitiveness
Feb 2021
Publication
Deployment and investments in hydrogen have accelerated rapidly in response to government commitments to deep decarbonisation establishing hydrogen as a key component in the energy transition.
To help guide regulators decision-makers and investors the Hydrogen Council collaborated with McKinsey & Company to release the report ‘Hydrogen Insights 2021: A Perspective on Hydrogen Investment Deployment and Cost Competitiveness’. The report offers a comprehensive perspective on market deployment around the world investment momentum as well as implications on cost competitiveness of hydrogen solutions.
The document can be downloaded from their website
To help guide regulators decision-makers and investors the Hydrogen Council collaborated with McKinsey & Company to release the report ‘Hydrogen Insights 2021: A Perspective on Hydrogen Investment Deployment and Cost Competitiveness’. The report offers a comprehensive perspective on market deployment around the world investment momentum as well as implications on cost competitiveness of hydrogen solutions.
The document can be downloaded from their website
Quantification of Temperature Dependence of Hydrogen Embrittlement in Pipeline Steel
Feb 2019
Publication
The effects of temperature on bulk hydrogen concentration and diffusion have been tested with the Devanathan–-Stachurski method. Thus a model based on hydrogen potential diffusivity loading frequency and hydrostatic stress distribution around crack tips was applied in order to quantify the temperature’s effect. The theoretical model was verified experimentally and confirmed a temperature threshold of 320 K to maximize the crack growth. The model suggests a nanoscale embrittlement mechanism which is generated by hydrogen atom delivery to the crack tip under fatigue loading and rationalized the ΔK dependence of traditional models. Hence this work could be applied to optimize operations that will prolong the life of the pipeline.
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.
Dislocation and Twinning Behaviors in High Manganese Steels in Respect to Hydrogen and Aluminum Alloying
Dec 2018
Publication
The dislocation and twinning evolution behaviors in high manganese steels Fe-22Mn-0.6C and Fe-17Mn-1.5Al-0.6C have been investigated under tensile deformation with and without diffusive hydrogen. The notched tensile tests were interrupted once primary cracks were detected using the applied direct current potential drop measurement. In parallel the strain distribution in the vicinity of the crack was characterized by digital image correlation using GOM optical system. The microstructure surrounding the crack was investigated by electron backscatter diffraction. Electron channeling contrast imaging was applied to reveal the evolution of dislocations stacking faults and deformation twins with respect to the developed strain gradient and amount of hydrogen. The results show that the diffusive hydrogen at the level of 26 ppm has a conspicuous effect on initiating stacking faults twin bundles and activating multiple deformation twinning systems in Fe-22Mn-0.6C. Eventually the interactions between deformation twins and grain boundaries lead to grain boundary decohesion in this material. In comparison hydrogen does not obviously affect the microstructure evolution namely the twinning thickness and the amount of activated twinning systems in Fe-17Mn-1.5Al-0.6C. The Al-alloyed grade reveals a postponed nucleation of deformation twins delayed onset of the secondary twinning system and develops finer twinning lamellae in comparison to the Al-free material. These observations explain the improved resistance to hydrogen-induced cracking in Al-alloyed TWIP steels.
Ab Initio Study of the Combined Effects of Alloying Elements and H on Grain Boundary Cohesion in Ferritic Steels
Mar 2019
Publication
Hydrogen enhanced decohesion is expected to play a major role in ferritic steels especially at grain boundaries. Here we address the effects of some common alloying elements C V Cr and Mn on the H segregation behaviour and the decohesion mechanism at a Σ5(310)[001] 36.9∘ grain boundary in bcc Fe using spin polarized density functional theory calculations. We find that V Cr and Mn enhance grain boundary cohesion. Furthermore all elements have an influence on the segregation energies of the interstitial elements as well as on these elements’ impact on grain boundary cohesion. V slightly promotes segregation of the cohesion enhancing element C. However none of the elements increase the cohesion enhancing effect of C and reduce the detrimental effect of H on interfacial cohesion at the same time. At an interface which is co-segregated with C H and a substitutional element C and H show only weak interaction and the highest work of separation is obtained when the substitute is Mn.
Expert Opinion Analysis on Renewable Hydrogen Storage Systems Potential in Europe
Nov 2016
Publication
Among the several typologies of storage technologies mainly on different physical principles (mechanical electrical and chemical) hydrogen produced by power to gas (P2G) from renewable energy sources complies with chemical storage principle and is based on the conversion of electrical energy into chemical energy by means of the electrolysis of water which does not produce any toxic or climate-relevant emission. This paper aims to pinpoint the potential uses of renewable hydrogen storage systems in Europe analysing current and potential locations regulatory framework governments’ outlooks economic issues and available renewable energy amounts. The expert opinion survey already used in many research articles on different topics including energy has been selected as an effective method to produce realistic results. The obtained results highlight strategies and actions to optimize the storage of hydrogen produced by renewables to face varying electricity demand and generation-driven fluctuations reducing the negative effects of the increasing share of renewables in the energy mix of European Countries.
In Situ Formed Ultrafine Metallic Ni from Nickel (II) Acetylacetonate Precursor to Realize an Exceptional Hydrogen Storage Performance of MgH2–Ni-EG Nanocomposite
Dec 2021
Publication
It has been well known that doping nano-scale catalysts can significantly improve both the kinetics and reversible hydrogen storage capacity of MgH2. However so far it is still a challenge to directly synthesize ultrafine catalysts (e.g. < 5 nm) mainly because of the complicated chemical reaction processes. Here a facile one-step high-energy ball milling process is developed to in situ form ultrafine Ni nanoparticles from the nickel acetylacetonate precursor in the MgH2 matrix. With the combined action of ultrafine metallic Ni and expanded graphite (EG) the formed MgH2–Ni-EG nanocomposite with the optimized doping amounts of Ni and EG can still release 7.03 wt.% H2 within 8.5 min at 300 °C after 10 cycles. At a temperature close to room temperature (50 °C) it can also absorb 2.42 wt.% H2 within 1 h It can be confirmed from the microstructural characterization analysis that the in situ formed ultrafine metallic Ni is transformed into Mg2Ni/Mg2NiH4 in the subsequent hydrogen absorption and desorption cycles. It is calculated that the dehydrogenation activation energy of the MgH2–Ni-EG nanocomposite is also reduced obviously in comparison with the pure MgH2. Our work provides a methodology to significantly improve the hydrogen storage performance of MgH2 by combining the in situ formed and uniformly dispersed ultrafine metallic catalyst from the precursor and EG.
Hydrogen Permeation Studies of Composite Supported Alumina-carbon Molecular Sieves Membranes: Separation of Diluted Hydrogen from Mixtures with Methane
Jun 2020
Publication
One alternative for the storage and transport of hydrogen is blending a low amount of hydrogen (up to 15 or 20%) into existing natural gas grids. When demanded hydrogen can be then separated close to the end users using membranes. In this work composite alumina carbon molecular sieves membranes (Al-CMSM) supported on tubular porous alumina have been prepared and characterized. Single gas permeation studies showed that the H2/CH4 separation properties at 30 °C are well above the Robeson limit of polymeric membranes. H2 permeation studies of the H2–CH4 mixture gases containing 5–20% of H2 show that the H2 purity depends on the H2 content in the feed and the operating temperature. In the best scenario investigated in this work for samples containing 10% of H2 with an inlet pressure of 7.5 bar and permeated pressure of 0.01 bar at 30 °C the H2 purity obtained was 99.4%.
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.
A New Model For Hydrogen-Induced Crack (HIC) Growth in Metal Alloy Pipelines Under Extreme Pressure
Dec 2020
Publication
Pipeline failure caused by Hydrogen-Induced Cracking (HIC) also known as Hydrogen Embrittlement (HE) is a pressing issue for the oil and natural gas industry. Bursts in pipelines are devastating and extremely costly. The explosive force of a bursting pipe can inflict fatal injuries to workers while the combined loss of product and effort to repair are highly costly to producers. Further pipeline failures due to HIC have a long lasting impact on the surrounding environment. Safe use and operation of such pipelines depend on a good understanding of the underlying forces that cause HIC. Specifically a reliable way to predict the growth rate of hydrogen-induced cracks is needed to establish a safe duration of service for each length of pipeline. Pipes that have exceeded or are near the end of their service life can then be retired before the risk of HIC-related failures becomes too high. However little is known about the mechanisms that drive HIC. To date no model has been put forth that accurately predicts the growth rate of fractures due to HIC under extreme pressures such as in the context of natural gas and petroleum pipelines. Herein a mathematical model for the growth of fractures by HIC under extreme pressures is presented. This model is derived from first principles and the results are compared with other models. The implications of these findings are discussed and a description of future work based on these findings is presented.
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.
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.
Crack Size Dependency of Shear-mode Fatigue Threshold in Bearing Steel Subjected to Continuous Hydrogen Charging
Jun 2019
Publication
Premature delamination failure characterized by the white structure flaking (WSF) or the white etching crack (WEC) often occurs in rolling element bearings and it deteriorates the durability of bearing substantially. It is known that this failure is caused by shear-mode (Mode II and Mode III) crack growth in conjunction with evolution and invasion of hydrogen into material during operation. To ensure the structural integrity associated with rolling element bearing it is important to clarify the effect of hydrogen on the shear-mode fatigue crack growth behavior near the threshold level.<br/>In our previous study the effect of hydrogen on the shear-mode fatigue crack growth behavior in a bearing steel of JIS SUJ2 was examined near the threshold level. Consequently it was shown that the threshold stress intensity factor (SIF) range for shear-mode fatigue crack growth decreased significantly by action of hydrogen. However the investigation was made only for a crack with a surface length of about 900 mm. To thoroughly understand the critical condition for delamination failure it is important to investigate the crack size dependency of the threshold level for a shear-mode small fatigue crack in the presence of hydrogen. In the present study correspondingly the threshold SIF ranges for a shear-mode crack with different length were additionally measured in the same material by using a novel technique that enables continuous charging of hydrogen in a specimen during long-term fatigue test. Then a clear reduction in crack growth rate and a crack size dependency of the threshold SIF range were observed under the environmental condition of continuous hydrogen charging.
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.
A Fully Renewable and Efficient Backup Power System with a Hydrogen-biodiesel-fueled IC Engine
Jan 2019
Publication
Renewable energy is free abundant clean and could contribute towards a significant reduction of the global warming emissions. It is massively introduced as a source of electricity production across the globe and is expected to become the primary source of energy within the following decades. However despite the naturally replenished energy the supply is not always available. For this reason it is necessary at times of excess energy any surplus quantity to be sufficiently captured stored and later used when a deficit occurs. In this paper an overview of a backup power system operating with a hydrogen-biodiesel dual-fuel internal combustion engine is provided. The system is utilizing the organic chemical hydride method for safe hydrogen storage and transportation. The high energy content of hydrogen stored in the form of an organic hydride under ambient conditions makes it an ideal energy backup medium for large-scale and long-term applications. The research work focusses on the operation and emissions output of the dual-fuel internal combustion engine running on fully renewable fuels and the results are compared with the conventional petroleum-derived diesel engine. Biodiesel-hydrogen operation shows significant benefits in the reduction of carbon and soot emissions but deteriorates the NOx formation compared to the conventional diesel-powered engines. The operation of the engine at high loads can provide high exhaust thermal energy while alternative combustion strategies are necessary to be implemented at low load conditions for the optimum operation of the backup power system.
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.
Minimum Entropy Generation in a Heat Exchanger in the Cryogenic Part of the Hydrogen Liquefaction Process: On the Validity of Equipartition and Disappearance of the Highway
May 2019
Publication
Liquefaction of hydrogen is a promising technology for transporting large quantities of hydrogen across long distances. A key challenge is the high power consumption. In this work we discuss refrigeration strategies that give minimum entropy production/exergy destruction in a plate-fin heat exchanger that cools the hydrogen from 47.8 K to 29.3 K. Two reference cases are studied; one where the feed stream enters at 20 bar and one where it enters at 80 bar. Catalyst in the hot layers speeds up the conversion of ortho-to para-hydrogen. Optimal control theory is used to formulate a minimization problem where the objective function is the total entropy production the control variable is the temperature of the refrigerant and the constrains are the balance equations for energy mass and momentum in the hot layers. The optimal refrigeration strategies give a reduction of the total entropy production of 8.7% in the 20-bar case and 4.3% in the 80-bar case. The overall heat transfer coefficient and duty is higher in the 20 bar case which compensates for the increase in entropy production due to a thermal mismatch that is avoided in the 80 bar case. This leads the second law efficiency of the 20 bar case (91%) to be similar to the 80 bar case (89%). We demonstrate that equipartition of the entropy production and equipartition of the thermal driving force are both excellent design principles for the process unit considered with total entropy productions deviating only 0.2% and 0.5% from the state of minimum entropy production. Equipartition of the thermal driving force i.e. a constant difference between the inverse temperatures of the hot and cold layers represents a particularly simple guideline that works remarkably well. We find that both heat transfer and the spin-isomer reaction contribute significantly to the entropy production throughout the length of the process unit. Unlike previous examples in the literature the process unit considered in this work is not characterized by a “reaction mode” at the inlet followed by a “heat transfer mode”. Therefore it does not follow a highway in state space i.e. a band that is particularly dense with energy efficient solutions. By artificially increasing the spin-isomer conversion rate the highway appears when the conversion rate becomes sufficiently high.
Study on Early Business Cases for H2 In Energy Storage and More Broadly Power to H2 Applications
Jun 2017
Publication
Hydrogen is widely recognised as a promising option for storing large quantities of renewable electricity over longer periods. For that reason in an energy future where renewables are a dominant power source opportunities for Power to- Hydrogen in the long-term appear to be generally acknowledged. The key challenge today is to identify concrete short-term investment opportunities based on sound economics and robust business cases. The focus of this study is to identify these early business cases and to assess their potential replicability within the EU from now until 2025. An essential part and innovative approach of this study is the detailed analysis of the power sector including its transmission grid constraints.
Seasonal Energy Storage in Aluminium for 100 Percent Solar Heat and Electricity Supply
Sep 2019
Publication
In order to reduce anthropogenic global warming governments around the world have decided to reduce CO2 emissions from fossil fuels dramatically within the next decades. In moderate and cold climates large amounts of fossil fuels are used for space heating and domestic hot water production in winter. Although on an annual base solar energy is available in large quantities in these regions least of the solar resource is available in winter when most of the energy is needed. Therefore solutions are needed to store and transfer renewable energy from summer to winter. In this paper a seasonal energy storage based on the aluminium redox cycle (Al3+→Al→ Al3+) is proposed. For charging electricity from solar or other renewable sources is used to convert aluminium oxide or aluminium hydroxide to elementary aluminium (Al3+→Al). In the discharging process aluminium is oxidized (Al→Al3+) releasing hydrogen heat and aluminium hydroxide or aluminium oxide as a by-product. Hydrogen is used in a fuel cell to produce electricity. Heat produced from the aluminium oxidation process and by the fuel cell is used for domestic hot water production and space heating. The chemical reactions and energy balances are presented and simulation results are shown for a system that covers the entire energy demand for electricity space heating and domestic hot water of a new multi-family building with rooftop photovoltaic energy in combination with the seasonal Al energy storage cycle. It shows that 7–11 kWp of photovoltaic installations and 350–530 kg Al would be needed per apartment for different Swiss climates. Environmental life cycle data shows that the global warming potential and non-renewable primary energy consumption can be reduced significantly compared to today's common practice of heating with natural gas and using electricity from the ENTSO-E network. The presumptive cost were estimated and indicate a possible cost-competitiveness for this system in the near future.
Hydrogen Effects in Corrosion: Discussion
Jun 2017
Publication
This session contained talks on the characterization of hydrogen-enhanced corrosion of steels and nickel-based alloys emphasizing the different observations across length scales from atomic-scale spectrographic to macro-scale fractographic examinations.
This article is the transcription of the recorded discussion of the session ‘Hydrogen Effects in Corrosion’ at the Royal Society discussion meeting Challenges of Hydrogen and Metals 16–18 January 2017. The text is approved by the contributors. M.A.S. transcribed the session and E.L.S. assisted in the preparation of the manuscript.
Link to document download on Royal Society Website
This article is the transcription of the recorded discussion of the session ‘Hydrogen Effects in Corrosion’ at the Royal Society discussion meeting Challenges of Hydrogen and Metals 16–18 January 2017. The text is approved by the contributors. M.A.S. transcribed the session and E.L.S. assisted in the preparation of the manuscript.
Link to document download on Royal Society Website
Investigation of Praseodymium and Samarium Co-doped Ceria as an Anode Catalyst for DIR-SOFC Fueled by Biogas
Aug 2020
Publication
The Pr and Sm co-doped ceria (with up to 20 mol.% of dopants) compounds were examined as catalytic layers on the surface of SOFC anode directly fed by biogas to increase a lifetime and the efficiency of commercially available DIR-SOFC without the usage of an external reformer.
The XRD SEM and EDX methods were used to investigate the structural properties and the composition of fabricated materials. Furthermore the electrical properties of SOFCs with catalytic layers deposited on the Ni-YSZ anode were examined by a current density-time and current density-voltage dependence measurements in hydrogen (24 h) and biogas (90 h). Composition of the outlet gasses was in situ analysed by the FTIR-based unit.
It has been found out that Ce0.9Sm0.1O2-δ and Ce0.8Pr0.05Sm0.15O2-δ catalytic layers show the highest stability over time and thus are the most attractive candidates as catalytic materials in comparison with other investigated lanthanide-doped ceria enhancing direct internal reforming of biogas in SOFCs.
The XRD SEM and EDX methods were used to investigate the structural properties and the composition of fabricated materials. Furthermore the electrical properties of SOFCs with catalytic layers deposited on the Ni-YSZ anode were examined by a current density-time and current density-voltage dependence measurements in hydrogen (24 h) and biogas (90 h). Composition of the outlet gasses was in situ analysed by the FTIR-based unit.
It has been found out that Ce0.9Sm0.1O2-δ and Ce0.8Pr0.05Sm0.15O2-δ catalytic layers show the highest stability over time and thus are the most attractive candidates as catalytic materials in comparison with other investigated lanthanide-doped ceria enhancing direct internal reforming of biogas in SOFCs.
Flexible Power and Hydrogen Production: Finding Synergy Between CCS and Variable Renewables
Dec 2019
Publication
The expansion of wind and solar power is creating a growing need for power system flexibility. Dispatchable power plants with CO2 capture and storage (CCS) offer flexibility with low CO2 emissions but these plants become uneconomical at the low running hours implied by renewables-based power systems. To address this challenge the novel gas switching reforming (GSR) plant was recently proposed. GSR can alternate between electricity and hydrogen production from natural gas offering flexibility to the power system without reducing the utilization rate of the capital stock embodied in CCS infrastructure. This study assesses the interplay between GSR and variable renewables using a power system model which optimizes investment and hourly dispatch of 13 different technologies. Results show that GSR brings substantial benefits relative to conventional CCS. At a CO2 price of V100/ton inclusion of GSR increases the optimal wind and solar share by 50% lowers total system costs by 8% and reduces system emissions from 45 to 4 kgCO2/MWh. In addition GSR produces clean hydrogen equivalent to about 90% of total electricity demand which can be used to decarbonize transport and industry. GSR could therefore become a key enabling technology for a decarbonization effort led by wind and solar power.
The Role of the Testing Rate on Small Punch Tests for the Estimation of Fracture Toughness in Hydrogen Embrittlement
Dec 2020
Publication
In this paper different techniques to test notched Small Punch (SPT) samples in fracture conditions in aggressive environments are studied based on the comparison of the micromechanisms at different rates. Pre-embrittled samples subsequently tested in air at rates conventionally employed (0.01 and 0.002 mm/s) are compared to embrittled ones tested in environment at the same rates (0.01 and 0.002 mm/s) and at a very slow rate (5E-5 mm/s). A set of samples tested in environment under a set of constant loads that produce very slow rates completes the experimental results. As a conclusion it is recommended to test SPT notched specimens in environment at very slow rates of around E-6 mm/s when characterizing in Hydrogen Embrittlement (HE) scenarios in order to allow the interaction material-environment to govern the process.
Adaptation of Hydrogen Transport Models at the Polycrystal Scale and Application to the U-bend Test
Dec 2018
Publication
Hydrogen transport and trapping equations are implemented in a FE software using User Subroutines and the obtained tool is applied to get the diffusion fields in a metallic sheet submitted to a U-Bend test. Based on a submodelling process mechanical and diffusion fields have been computed at the polycrystal scale from which statistical evaluation of the risk of failure of the sample has been estimated.
Static and Dynamic Studies of Hydrogen Adsorption on Nanoporous Carbon Gels
Jun 2019
Publication
Although hydrogen is considered to be one of the most promising green fuels its efficient and safe storage and use still raise several technological challenges. Physisorption in porous materials may offer an attractive means of storage but the state-of-the-art capacity of these kinds of systems is still limited. To overcome the present drawbacks a deeper understanding of the adsorption and surface diffusion mechanism is required along with new types of adsorbents developed and/or optimised for this purpose. In the present study we compare the hydrogen adsorption behaviour of three carbon gels exhibiting different porosity and/or surface chemistry. In addition to standard adsorption characterisation techniques neutron spin-echo spectroscopy (NSE) has been also applied to explore the surface mobility of the adsorbed hydrogen. Our results reveal that both the porosity and surface chemistry of the adsorbent play a significant role in the adsorption of in these systems.
The Microstructure Study of the Hydrogenated Titanium Specimens Tested at High Temperature Creep for Long-term Tensile Strength
Feb 2020
Publication
Experimental tests of flat titanium samples at a temperature of 450 °C stretched with a constant force up to destruction were carried out. Titanium samples were hydrogenated in the Moscow Aviation Institute laboratory to a hydrogen content of 0.1 % 0.3 % and 0.6 % by weight of the specimen and then tested in the laboratory of Lomonosov Moscow State University. From the experiments the time to failure the localization time of the deformations and the stress distribution along the longitudinal coordinate of the sample over time were obtained. A metallographic study was conducted and the phase composition was investigated in Moscow Aviation Institute. The effect of hydrogen on long-term strength mechanical characteristics and phase composition has been elucidated.
Polymer–Ceramic Composite Membranes for Water Removal in Membrane Reactors
Jun 2021
Publication
Methanol can be obtained through CO2 hydrogenation in a membrane reactor with higher yield or lower pressure than in a conventional packed bed reactor. In this study we explore a new kind of membrane with the potential suitability for such membrane reactors. Silicone–ceramic composite membranes are synthetized and characterized for their capability to selectively remove water from a mixture containing hydrogen CO2 and water at temperatures typical for methanol synthesis. We show that this membrane can achieve selective permeation of water under such harsh conditions and thus is an alternative candidate for use in membrane reactors for processes where water is one of the products and the yield is limited by thermodynamic equilibrium.
Atomistic Modelling of Light-element Co-segregation at Structural Defects in Iron
Dec 2018
Publication
Studying the behaviour of hydrogen in the vicinity of extended defects such as grain boundaries dislocations nanovoids and phase boundaries is critical in understanding the phenomenon of hydrogen embrittlement. A key complication in this context is the interplay between hydrogen and other segregating elements. Modelling the competition of H with other light elements requires an efficient description of the interactions of compositionally complex systems with the system sizes needed to appropriately describe extended defects often precluding the use of direct ab initio approaches. In this regard we have developed novel electronic structure approaches to understand the energetics and mutual interactions of light elements at representative structural features in high-strength ferritic steels. Using this approach we examine the co-segregation of hydrogen with carbon at chosen grain boundaries in α-iron. We find that the strain introduced by segregated carbon atoms at tilt grain boundaries increases the solubility of hydrogen close to the boundary plane giving a higher H concentration in the vicinity of the boundary than in a carbon-free case. Via simulated tensile tests we find that the simultaneous presence of carbon and hydrogen at grain boundaries leads to a significant decrease in the elongation to fracture compared with the carbon-free case.
Indentation and Hydride Orientation in Zr-2.5%Nb Pressure Tube Material
Jun 2019
Publication
In this study indentations were made on Zr-2.5%Nb pressure tube material to induce multi-axial stress field. An I-shaped punch mark was indented on the Pressure tube material with predefined punch load. Later material was charged with 50 wppm of hydrogen. The samples near the punch mark were metallographically examined for hydrides orientation. It was observed that hydrides exhibited preferentially circumferential orientation far away from the indent to mixed orientation containing both circumferential and radial hydrides near the indent. This is probably as a result of stress field generated by indentation. Extent of radial hydride formation was observed to be varying with indentation load.
Stress Corrosion Behavior of AM50Gd Magnesium Alloy in Different Environments
May 2019
Publication
A new type of high strength corrosion-resistant magnesium alloy was prepared by adding 1% rare earth Gd to AM50 and then treated with hot extrusion method. The stress corrosion properties of the new materials in air pure water 0.5 mol/L NaCl and 0.5 mol/L Na2SO4 solution were studied by the slow strain rate tensile (SSRT) test in situ open circuit potential test Tafel curve test stereomicroscope SEM and EDS. The results showed the following. The stress corrosion sensitivity of the material in different environments was Na2SO4> NaCl > distilled water > air. According to the Tafel curves measured at 0 and 100 MPa the corrosion voltage decreased little and the corrosion current density increased rapidly under 100 Pa. This was because the film of the corrosion product ruptured to form a large cathode and a small anode which resulted in a large instantaneous corrosion current. The mechanism of hydrogen embrittlement and anodic dissolution together affected the stress corrosion behavior of the alloy. In distilled water hydrogen embrittlement played a major role while in NaCl and Na2SO4solution hydrogen embrittlement and anodic dissolution were both affected. The direct reason of the stress corrosion crack (SCC) samples’ failure was the cracks expanding rapidly at the bottom of pit which was caused by corrosion.
Marked Degradation of Tensile Properties Induced by Plastic Deformation after Interactions between Strain-Induced Martensite Transformation and Hydrogen for Type 316L Stainless Steel
Jul 2020
Publication
Marked degradation of tensile properties induced by plastic deformation after dynamic interactions between strain-induced martensite transformation and hydrogen has been investigated for type 316L stainless steel by hydrogen thermal desorption analysis. Upon modified hydrogen charging reported previously the amount of hydrogen desorbed in the low temperature range increases; the degradation of tensile properties induced by interactions between plastic deformation and hydrogen at 25 °C or induced by interactions between martensite transformation and hydrogen at −196 °C occurs even for the stainless steel with high resistance to hydrogen embrittlement. The hydrogen thermal desorption behavior is changed by each interaction suggesting changes in hydrogen states. For specimen fractured at 25 °C the facet-like morphology and transgranular fracture are observed on the outer part of the fracture surface. At −196 °C a quasi-cleave fracture is observed at the initiation area. Modified hydrogen charging significantly interacts both plastic deformation and martensite transformation eventually enhancing the degradation of tensile properties. Upon plastic deformation at 25° C after the interactions between martensite transformation and hydrogen by straining to 0.2 at −196 °C cracks nucleate in association with martensite formed by the interactions at −196 °C and marked degradation of tensile properties occurs. It is likely that the interactions between martensite transformation and hydrogen induce damage directly related to the degradation thereby affecting subsequent deformation. Upon dehydrogenation after the interactions between the martensite transformation and hydrogen no degradation of tensile properties is observed. The damage induced by the interactions between martensite transformation and hydrogen probably changes to harmless defects during dehydrogenation.
Effects of Hydrogen Addition on Design, Maintenance and Surveillance of Gas Networks
Jul 2021
Publication
Hydrogen when is blended with natural gas over time degrades the materials used for pipe transport. Degradation is dependent on the proportion of hydrogen added to the natural gas. The assessment is made according to hydrogen permeation risk to the integrity of structures adaptation of surveillance and maintenance of equipment. The paper gives a survey of HE and its consequence on the design and maintenance. It is presented in a logical sequence: the design before use; the hydrogen embrittlement (HE) effects on Maximum Allowable Operating Pressure (MAOP); maintenance and surveillance during use of smooth and damaged pipes; and particularly for crack-like defects corrosion defects and dents.
Degradation Mechanisms in the Operation of Pressured Pipelines
Aug 2019
Publication
Many non-standard situations like subsoil slipping vibrations ... as well as degradation mechanisms of pipeline materials can occur in the operation of pressured pipelines. The article deals with the mechanisms of the degradation processes and their formation like corrosion brittleness and steel ageing that may occur in operation of pipeline systems. Material ageing of steels is documented on specimens created from pipeline materials and obtained by experimental measurements on these specimens after the multi-annual operation.
Warm Pre-Strain: Strengthening the Metastable 304L Austenitic Stainless Steel without Compromising Its Hydrogen Embrittlement Resistance
Nov 2017
Publication
Plastic pre-strains were applied to the metastable 304L austenitic stainless steel at both room temperature (20 °C) and higher temperatures (i.e. 50 80 and 100 °C) and then the hydrogen embrittlement (HE) susceptibility of the steel was evaluated by cathodically hydrogen-charging and tensile testing. The 20 °C pre-strain greatly strengthened the steel but simultaneously significantly increased the HE susceptibility of the steel since α′ martensite was induced by the pre-strain causing the pre-existence of α′ martensite which provided “highways” for hydrogen to transport deep into the steel during the hydrogen-charging. Although the warm pre-strains did not strengthen the steel as significantly as the 20 °C pre-strain they retained the HE resistance of the steel. This is because the higher temperatures particularly 80 and 100 °C suppressed the α′ martensite transformation during the pre-straining. Pre-strain at a temperature slightly higher than room temperature has a potential to strengthen the metastable 304L austenitic stainless steel without compromising its initial HE resistance.
Project Cavendish - National Grid Gas Transmission
Sep 2020
Publication
The Isle of Grain (IoG) presents a technically feasible commercially viable strategic location to build and operate a hydrogen production facility which would be a key enabler to the UK meeting the Net Zero 2050 target.
As highlighted in the ‘Net Zero – The UK’s contribution to stopping global warming’ report published by The Committee on Climate Change in May 2019 hydrogen is set to have a major part to play in reducing UK carbon dioxide emissions. Carbon Capture and Storage (CCS) is also seen as essential to support those supplies.
The report further recognises that this will involve increased investments and that CCS and hydrogen will require both capital funding and revenue support.
For hydrogen to have a part to play in the decarbonisation of London and the south east of England a large-scale hydrogen production facility will be required which will provide a multi vector solution through the decarbonisation of the gas grid.
This report and any attachment is freely available on the ENA Smarter Networks Portal here. IGEM Members can download the report and any attachment directly by clicking on the pdf icon above.
As highlighted in the ‘Net Zero – The UK’s contribution to stopping global warming’ report published by The Committee on Climate Change in May 2019 hydrogen is set to have a major part to play in reducing UK carbon dioxide emissions. Carbon Capture and Storage (CCS) is also seen as essential to support those supplies.
The report further recognises that this will involve increased investments and that CCS and hydrogen will require both capital funding and revenue support.
For hydrogen to have a part to play in the decarbonisation of London and the south east of England a large-scale hydrogen production facility will be required which will provide a multi vector solution through the decarbonisation of the gas grid.
This report and any attachment is freely available on the ENA Smarter Networks Portal here. IGEM Members can download the report and any attachment directly by clicking on the pdf icon above.
Life Cycle Environmental Analysis of a Hydrogen-based Energy Storage System for Remote Applications
Mar 2022
Publication
Energy storage systems are required to address the fluctuating behaviour of variable renewable energy sources. The environmental sustainability of energy storage technologies should be carefully assessed together with their techno-economic feasibility. In this work an environmental analysis of a renewable hydrogen-based energy storage system has been performed making use of input parameters made available in the framework of the European REMOTE project. The analysis is applied to the case study of the Froan islands (Norway) which are representative of many other insular microgrid sites in northern Europe. The REMOTE solution is compared with other scenarios based on fossil fuels and submarine connections to the mainland grid. The highest climate impacts are found in the dieselbased configuration (1090.9 kgCO2eq/MWh) followed by the REMOTE system (148.2 kgCO2eq/MWh) and by the sea cable scenario (113.7 kgCO2eq/MWh). However the latter is biased by the very low carbon intensity of the Norwegian electricity. A sensitivity analysis is then performed on the length of the sea cable and on the CO2 emission intensity of electricity showing that local conditions have a strong impact on the results. The REMOTE system is also found to be the most cost-effective solution to provide electricity to the insular community. The in-depth and comparative (with reference to possible alternatives) assessment of the renewable hydrogen-based system aims to provide a comprehensive overview about the effectiveness and sustainability of these innovative solutions as a support for off-grid remote areas.
Decrease in Hydrogen Embrittlement Susceptibility of 10B21 Screws by Bake Aging
Aug 2016
Publication
The effects of baking on the mechanical properties and fracture characteristics of low-carbon boron (10B21) steel screws were investigated. Fracture torque tests and hydrogen content analysis were performed on baked screws to evaluate hydrogen embrittlement (HE) susceptibility. The diffusible hydrogen content within 10B21 steel dominated the fracture behavior of the screws. The fracture torque of 10B21 screws baked for a long duration was affected by released hydrogen. Secondary ion mass spectroscopy (SIMS) result showed that hydrogen content decreased with increasing baking duration and thus the HE susceptibility of 10B21 screws improved. Diffusible hydrogen promoted crack propagation in high-stress region. The HE of 10B21 screws can be prevented by long-duration baking.
Impact Assessment of Hydrogen Transmission on TD1 Parallel Pipeline Separation Distances
Mar 2021
Publication
The recommended minimum separation distances in IGEM/TD/1 were based on a research programme that studied the different ways in which a failure of one buried natural gas transmission pipeline can affect another similar pipeline installed adjacent to the first taking account of the initial pressure wave propagating through the ground the size of the ground crater produced and the threat of escalation from fire if the second pipeline is exposed. The methodology developed from the research was first published in 2010 and is implemented in a software program (“PROPHET”). The distances in IGEM/TD/1 are generally cautious and are essentially determined by the size of the ground crater produced by pipeline ruptures as predicted by the methodology.
To assess the impact of hydrogen transmission on the recommended separation distances the possibility of one pipeline transporting natural gas and the other transporting hydrogen was considered as well as both pipelines transporting hydrogen. The following steps were carried out to assess the impact of hydrogen transmission on parallel pipeline separation distances drawing on existing knowledge only:
To assess the impact of hydrogen transmission on the recommended separation distances the possibility of one pipeline transporting natural gas and the other transporting hydrogen was considered as well as both pipelines transporting hydrogen. The following steps were carried out to assess the impact of hydrogen transmission on parallel pipeline separation distances drawing on existing knowledge only:
- Estimate the ground pressure loading predicted from a hydrogen pipeline rupture.
- Consider the ground pressure effect on a parallel natural gas or hydrogen pipeline.
- Evaluate available ground crater formation models and assess if existing natural gas model is cautious for hydrogen.
- Consider effects of thermal loading due to hydrogen fires where recommended natural gas separation distances are not met.
- Ground pressure loading: The current natural gas methodology is cautious.
- Ground pressure effects: The current natural gas methodology is applicable (no change for hydrogen).
- Ground crater formation: The current natural gas methodology is cautious for ruptures and applicable for punctures (almost no change for hydrogen).
- Thermal loading: The current natural gas methodology is cautious for the thermal loading from ruptures but not necessarily cautious for punctures. Calculations of the minimum flow velocity required to prevent failure of a natural gas pipeline are not cautious for hydrogen.
Effect of Hydrogen-storage Pressure on the Detonation Characteristics of Emulsion Explosives Sensitized by Glass Microballoons
Mar 2021
Publication
In this study hydrogen-storage glass microballoons were introduced into emulsion explosives to improve the detonation performance of the explosives. The effect of hydrogen-storage pressure on the detonation characteristics of emulsion explosives was systematically investigated. Detonation velocity experiments shows that the change of sensitizing gas and the increase of hydrogen pressure have different effects on the detonation velocity. The experimental parameters of underwater explosion increase first and then decreases with the increase of hydrogen pressure. The decrease of these parameters indicates that the strength of glass microballoons is the limiting factor to improve the detonation performance of hydrogen-storage emulsion explosives. Compared with the traditional emulsion explosives the maximum peak pressure of shock wave of hydrogen-storage emulsion explosives increases by 10.6% at 1.0 m and 10.2% at 1.2 m the maximum values of shock impulse increase by 5.7% at 1.0 m and 19.4% at 1.2 m. The stored hydrogen has dual effects of sensitizers and energetic additives which can improve the energy output of emulsion explosives.
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
Techno-Economics Optimization of H2 and CO2 Compression for Renewable Energy Storage and Power-to-Gas Applications
Nov 2021
Publication
The decarbonization of the industrial sector is imperative to achieve a sustainable future. Carbon capture and storage technologies are the leading options but lately the use of CO2 is also being considered as a very attractive alternative that approaches a circular economy. In this regard power to gas is a promising option to take advantage of renewable H2 by converting it together with the captured CO2 into renewable gases in particular renewable methane. As renewable energy production or the mismatch between renewable production and consumption is not constant it is essential to store renewable H2 or CO2 to properly run a methanation installation and produce renewable gas. This work analyses and optimizes the system layout and storage pressure and presents an annual cost (including CAPEX and OPEX) minimization. Results show the proper compression stages need to achieve the storage pressure that minimizes the system cost. This pressure is just below the supercritical pressure for CO2 and at lower pressures for H2 around 67 bar. This last quantity is in agreement with the usual pressures to store and distribute natural gas. Moreover the H2 storage costs are higher than that of CO2 even with lower mass quantities; this is due to the lower H2 density compared with CO2 . Finally it is concluded that the compressor costs are the most relevant costs for CO2 compression but the storage tank costs are the most relevant in the case of H2.
Hydrogen Storage Behavior of Mg-based Alloy Catalyzed by Carbon-cobalt Composites
Feb 2021
Publication
The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction. The catalysis of Co@C composites on the hydrogen storage behavior of Mg90Ce5Y5 alloy was investigated in detail by XRD SEM TEM PCI and DSC method. Because of the synergistic catalytic function of C and Co in C@Co nanocomposites the Mg90Ce5Y5 alloy with 10 wt.% C@Co shows the excellent hydrogen absorption and desorption performances. Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300 °C. Meanwhile the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol−1 H2 after the addition of the C@Co composites. This positive effect attributes to the C layer with the high defect density and the Co nanoparticles which reduces the energy barriers for the nucleation of Mg/MgH2 phase and the recombination of hydrogen molecule. Besides the C@Co composites also improve the activation property of the Mg90Ce5Y5 alloy which was fully activated in the first cycle. Moreover the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased. Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy these differences are so small that the improvement on thermodynamics can hardly be seen.
Intelligent Natural Gas and Hydrogen Pipeline Dispatching Using the Coupled Thermodynamics-Informed Neural Network and Compressor Boolean Neural Network
Feb 2022
Publication
Natural gas pipelines have attracted increasing attention in the energy industry thanks to the current demand for green energy and the advantages of pipeline transportation. A novel deep learning method is proposed in this paper using a coupled network structure incorporating the thermodynamics-informed neural network and the compressor Boolean neural network to incorporate both functions of pipeline transportation safety check and energy supply predictions. The deep learning model is uniformed for the coupled network structure and the prediction efficiency and accuracy are validated by a number of numerical tests simulating various engineering scenarios including hydrogen gas pipelines. The trained model can provide dispatchers with suggestions about the number of phases existing during the transportation as an index showing safety while the effects of operation temperature pressure and compositional purity are investigated to suggest the optimized productions.
Electrochemical and Stress Corrosion Mechanism of Submarine Pipeline in Simulated Seawater in Presence of Different Alternating Current Densities
Jun 2018
Publication
In this study electrochemical measurements immersion tests and slow strain rate tensile (SSRT) tests were applied to investigate the electrochemical and stress corrosion cracking (SCC) behavior of X70 steel in simulated seawater with the interference of different alternating current (AC) densities. The results indicate that AC significantly strengthens the cathodic reaction especially the oxygen reduction reaction. Simultaneously hydrogen evolution reaction occurs when the limiting diffusion current density of oxygen reaches and thus icorr sharply increases with the increase in AC density. Additionally when AC is imposed the X70 steel exhibits higher SCC susceptibility in the simulated seawater and the susceptibility increases with the increasing AC density. The SCC mechanism is controlled by both anodic dissolution (AD) and hydrogen embrittlement (HE) with the interference of AC.
Interaction of Hydrogen with the Bulk, Surface and Subsurface of Crystalline RuO2 from First Principles
Feb 2021
Publication
Hydrogen and its interaction with metal oxide surfaces is of major importance for a wide range of research and applied fields spanning from catalysis energy storage microelectronics to metallurgy. This paper reviews state of the art of first principles calculations on the well-known ruthenium oxide (RuO2) surface in its (110) orientation and its interaction with hydrogen. In addition to it the paper also fills gaps in knowledge with new calculations and results on the (001) surface. Bulk and surface interactions are thoroughly reviewed. This includes systematic analysis of adsorption sites local agglomeration propensity of hydrogen and migration pathways in which literature data and their potential deviations are explained. We notably discuss novel results on propensity for agglomeration of hydrogen within bulk channels [001] oriented in which the proton-like behavior of adsorbed hydrogen hinders further agglomeration in adjacent channels. The paper brings new insights into the migration pathways on the surface and in bulk both exhibiting preferential diffusion paths along the [001] direction. The paper finally investigates the subsurface region. We show that while the subsurface has more stable sites for adsorption compared to bulk its accessibility from the surface shows prohibitive activation barriers inhibiting penetration into subsurface and bulk. We further calculate and discuss adsorption and penetration processes on the alternative RuO2 (001) surface.
Optimal Configuration of the Integrated Charging Station for PV and Hydrogen Storage
Oct 2021
Publication
This paper designs the integrated charging station of PV and hydrogen storage based on the charging station. The energy storage system includes hydrogen energy storage for hydrogen production and the charging station can provide services for electric vehicles and hydrogen vehicles at the same time. To improve the independent energy supply capacity of the hybrid charging station and reduce the cost the components are reasonably configured. To minimize the configuration cost of the integrated charging station and the proportion of power purchase to the demand of the charging station the energy flow strategy of the integrated charging station is designed and the optimal configuration model of optical storage capacity is constructed. The NSGA-II algorithm optimizes the non-inferior Pareto solution set and a fuzzy comprehensive evaluation evaluates the optimal configuration.
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.
Microalloyed Steels through History until 2018: Review of Chemical Composition, Processing and Hydrogen Service
May 2018
Publication
Microalloyed steels have evolved in terms of their chemical composition processing and metallurgical characteristics since the beginning of the 20th century in the function of fabrication costs and mechanical properties required to obtain high-performance materials needed to accommodate for the growing demands of gas and hydrocarbons transport. As a result of this microalloyed steels present a good combination of high strength and ductility obtained through the addition of microalloying elements thermomechanical processing and controlled cooling processes capable of producing complex microstructures that improve the mechanical properties of steels. These controlled microstructures can be severely affected and result in catastrophic failures due to the atomic hydrogen diffusion that occurs during the corrosion process of pipeline steel. Recently a martensite–bainite microstructure with acicular ferrite has been chosen as a viable candidate to be used in environments with the presence of hydrogen. The aim of this review is to summarize the main changes of chemical composition processing techniques and the evolution of the mechanical properties throughout recent history on the use of microalloying in high strength low alloy steels as well as the effects of hydrogen in newly created pipelines examining the causes behind the mechanisms of hydrogen embrittlement in these steels.
Comparison of Hydrogen Powertrains with the Battery Powered Electric Vehicle and Investigation of Small-Scale Local Hydrogen Production Using Renewable Energy
Jan 2021
Publication
Climate change is one of the major problems that people face in this century with fossil fuel combustion engines being huge contributors. Currently the battery powered electric vehicle is considered the predecessor while hydrogen vehicles only have an insignificant market share. To evaluate if this is justified different hydrogen power train technologies are analyzed and compared to the battery powered electric vehicle. Even though most research focuses on the hydrogen fuel cells it is shown that despite the lower efficiency the often-neglected hydrogen combustion engine could be the right solution for transitioning away from fossil fuels. This is mainly due to the lower costs and possibility of the use of existing manufacturing infrastructure. To achieve a similar level of refueling comfort as with the battery powered electric vehicle the economic and technological aspects of the local small-scale hydrogen production are being investigated. Due to the low efficiency and high prices for the required components this domestically produced hydrogen cannot compete with hydrogen produced from fossil fuels on a larger scale
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.
Effects of Hot Stamping and Tempering on Hydrogen Embrittlement of a Low-Carbon Boron-Alloyed Steel
Dec 2018
Publication
The effects of hot stamping (HS) and tempering on the hydrogen embrittlement (HE) behavior of a low-carbon boron-alloyed steel were studied by using slow strain rate tensile (SSRT) tests on notched sheet specimens. It was found that an additional significant hydrogen desorption peak at round 65–80 °C appeared after hydrogen-charging the corresponding hydrogen concentration (CHr) of the HS specimen was higher than that of the directed quenched (DQ) specimen and subsequent low-temperature tempering gave rise to a decrease of CHr. The DQ specimen exhibited a comparatively high HE susceptibility while tempering treatment at 100 °C could notably alleviate it by a relative decrease of ~24% at no expanse of strength and ductility. The HS specimen demonstrated much lower HE susceptibility compared with the DQ specimen and tempering at 200 °C could further alleviate its HE susceptibility. SEM analysis of fractured SSRT surfaces revealed that the DQ specimen showed a mixed transgranular-intergranular fracture while the HS and low-temperature tempered specimens exhibited a predominant quasi-cleavage transgranular fracture. Based on the obtained results we propose that a modified HS process coupled with low-temperature tempering treatment is a promising and feasible approach to ensure a low HE susceptibility for high-strength automobile parts made of this type of steel.
Two-dimensional Vanadium Carbide for Simultaneously Tailoring the Hydrogen Sorption Thermodynamics and Kinetics of Magnesium Hydride
May 2021
Publication
Magnesium hydride (MgH2) is a potential material for solid-state hydrogen storage. However the thermodynamic and kinetic properties are far from practical application in the current stage. In this work two-dimensional vanadium carbide (V2C) MXene with layer thickness of 50−100 nm was fist synthesized by selectively HF-etching the Al layers from V2AlC MAX phase and then introduced into MgH2 to improve the hydrogen sorption performances of MgH2. The onset hydrogen desorption temperature of MgH2 with V2C addition is significantly reduced from 318 °C for pure MgH2 to 190 °C with a 128 °C reduction of the onset temperature. The MgH2+ 10 wt% V2C composite can release 6.4 wt% of H2 within 10 min at 300 °C and does not loss any capacity for up to 10 cycles. The activation energy for the hydrogen desorption reaction of MgH2 with V2C addition was calculated to be 112 kJ mol−1 H2 by Arrhenius's equation and 87.6 kJ mol−1 H2 by Kissinger's equation. The hydrogen desorption reaction enthalpy of MgH2 + 10 wt% V2C was estimated by van't Hoff equation to be 73.6 kJ mol−1 H2 which is slightly lower than that of the pure MgH2 (77.9 kJ mol−1 H2). Microstructure studies by XPS TEM and SEM showed that V2C acts as an efficient catalyst for the hydrogen desorption reaction of MgH2. The first-principles density functional theory (DFT) calculations demonstrated that the bond length of Mg−H can be reduced from 1.71 Å for pure MgH2 to 2.14 Å for MgH2 with V2C addition which contributes to the destabilization of MgH2. This work provides a method to significantly and simultaneously tailor the hydrogen sorption thermodynamics and kinetics of MgH2 by two-dimensional MXene materials.
Combined Cooling and Power Management Strategy for a Standalone House Using Hydrogen and Solar Energy
May 2021
Publication
Tropical climate is characterized by hot temperatures throughout the year. In areas subject to this climate air conditioning represents an important share of total energy consumption. In some tropical islands there is no electric grid; in these cases electricity is often provided by diesel generators. In this study in order to decarbonize electricity and cooling production and to improve autonomy in a standalone application a microgrid producing combined cooling and electrical power was proposed. The presented system was composed of photovoltaic panels a battery an electrolyzer a hydrogen tank a fuel cell power converters a heat pump electrical loads and an adsorption cooling system. Electricity production and storage were provided by photovoltaic panels and a hydrogen storage system respectively while cooling production and storage were achieved using a heat pump and an adsorption cooling system respectively. The standalone application presented was a single house located in Tahiti French Polynesia. In this paper the system as a whole is presented. Then the interaction between each element is described and a model of the system is presented. Thirdly the energy and power management required in order to meet electrical and thermal needs are presented. Then the results of the control strategy are presented. The results showed that the adsorption cooling system provided 53% of the cooling demand. The use of the adsorption cooling system reduced the needed photovoltaic panel area the use of the electrolyzer and the use of the fuel cell by more than 60% and reduced energy losses by 7% (compared to a classic heat pump) for air conditioning.
Evaluation of Hydrogen Permeation Characteristics in Rubbery Polymers
Oct 2020
Publication
To find suitable sealing material with low permeability against hydrogen the elaborated evaluation techniques for hydrogen transport properties are necessary. We developed two techniques determining the permeability of hydrogen including software for diffusion behavior analysis. The techniques contain gas chromatography and volumetric collection of hydrogen gas. By measuring the hydrogen released from polymer samples with respect to the elapsed time after being decompressed from the high pressure total amount of adsorption and diffusivity (D) of hydrogen are evaluated with self-developed program of Fick's diffusion equation specified to a sample shape. The solubility (S) and permeability (P) of the polymers are determined through Henry's law and a relation of P=SD respectively. Developed techniques were applied to three kinds of spherical-shaped sealing rubbers NBR EPDM and FKM. The D S and P have been measured as function of pressure. The permeability obtained by both methods are discussed with Comsol simulation.
Water Removal from LOHC Systems
Oct 2020
Publication
Liquid organic hydrogen carriers (LOHC) store hydrogen by reversible hydrogenation of a carrier material. Water can enter the system via wet hydrogen coming from electrolysis as well as via moisture on the catalyst. Removing this water is important for reliable operation of the LOHC system. Different approaches for doing this have been evaluated on three stages of the process. Drying of the hydrogen before entering the LOHC system itself is preferable. A membrane drying process turns out to be the most efficient way. If the water content in the LOHC system is still so high that liquid–liquid demixing occurs it is crucial for water removal to enhance the slow settling. Introduction of an appropriate packing can help to separate the two phases as long as the volume flow is not too high. Further drying below the rather low solubility limit is challenging. Introduction of zeolites into the system is a possible option. Water adsorbs on the surface of the zeolite and moisture content is therefore decreased.
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.
Analysis of the Hydrogen Induced Cracking by Means of the Small Punch Test: Effect of the Specimen Geometry and the Hydrogen Pre-Charge Mode
Nov 2018
Publication
This paper presents a simplified procedure to analyse the Hydrogen Induced Cracking (HIC) of structural steels by means of the Small Punch Test (SPT). Two types of notched specimens were used: one with through-thickness lateral notch and another with surface longitudinal notch. The results for conventional specimens were compared with those for hydrogen pre-charged specimens. For this purpose two different methods to introduce hydrogen in the specimens were used: cathodic/electrochemical pre-charging and pressurized gaseous hydrogen pre-charging. The results obtained with both methods are also discussed.
Exergy and Exergoeconomic Analysis of Hydrogen and Power Cogeneration Using an HTR Plant
Mar 2021
Publication
This paper proposes using sodium-cooled fast reactor technologies for use in hydrogen vapor methane (SMR) modification. Using three independent energy rings in the Russian BN-600 fast reactor steam is generated in one of the steam-generating cycles with a pressure of 13.1 MPa and a temperature of 505 °C. The reactor's second energy cycles can increase the gas-steam mixture's temperature to the required amount for efficient correction. The 620 ton/hr 540 °C steam generated in this cycle is sufficient to supply a high-temperature synthesis current source (700 °C) which raises the steam-gas mixture's temperature in the reactor. The proposed technology provides a high rate of hydrogen production (approximately 144.5 ton/hr of standard H2) also up to 25% of the original natural gas in line with existing SMR technology for preparing and heating steam and gas mixtures will be saved. Also exergy analysis results show that the plant's efficiency reaches 78.5% using HTR heat for combined hydrogen and power generation.
Stress Corrosion Cracking of Gas Pipeline Steels of Different Strength
Jul 2016
Publication
With the development of the natural gas industry gas transmission pipelines have been developed rapidly in terms of safety economy and efficiency. Our recent studies have shown that an important factor of main pipelines serviceability loss under their long-term service is the in-bulk metal degradation of the pipe wall. This leads to the loss of the initial mechanical properties primarily resistance to brittle fracture which were set in engineering calculations at the pipeline design stage. At the same time stress corrosion cracking has been identified as one of the predominant failures in pipeline steels in humid environments which causes rupture of high-pressure gas transmission pipes as well as serious economic losses and disasters.
In the present work the low-carbon pipeline steels with different strength levels from the point of view of their susceptibility to stress corrosion cracking in the as-received state and after in-laboratory accelerated degradation under environmental conditions similar to those of an acidic soil were investigated. The main objectives of this study were to determine whether the development of higher strength materials led to greater susceptibility to stress corrosion cracking and whether degraded pipeline steels became more susceptible to stress corrosion cracking than in the as-received state. The procedure of accelerated degradation of pipeline steels was developed and introduced in laboratory under the combined action of axial loading and hydrogen charging. It proved to be reliable and useful to performed laboratory simulation of in-service degradation of pipeline steels with different strength. The in-laboratory degraded 17H1S and X60 pipeline steels tested in the NS4 solution saturated with CO2 under open circuit potential revealed the susceptibility to stress corrosion cracking reflected in the degradation of mechanical properties and at the same time the degraded X60 steel showed higher resistance to stress corrosion cracking than the degraded 17H1S steel. Fractographic observation confirmed the pipeline steels hydrogen embrittlement caused by the permeated hydrogen.
In the present work the low-carbon pipeline steels with different strength levels from the point of view of their susceptibility to stress corrosion cracking in the as-received state and after in-laboratory accelerated degradation under environmental conditions similar to those of an acidic soil were investigated. The main objectives of this study were to determine whether the development of higher strength materials led to greater susceptibility to stress corrosion cracking and whether degraded pipeline steels became more susceptible to stress corrosion cracking than in the as-received state. The procedure of accelerated degradation of pipeline steels was developed and introduced in laboratory under the combined action of axial loading and hydrogen charging. It proved to be reliable and useful to performed laboratory simulation of in-service degradation of pipeline steels with different strength. The in-laboratory degraded 17H1S and X60 pipeline steels tested in the NS4 solution saturated with CO2 under open circuit potential revealed the susceptibility to stress corrosion cracking reflected in the degradation of mechanical properties and at the same time the degraded X60 steel showed higher resistance to stress corrosion cracking than the degraded 17H1S steel. Fractographic observation confirmed the pipeline steels hydrogen embrittlement caused by the permeated hydrogen.
Understanding Corrosion Morphology of Duplex Stainless Steel Wire in Chloride Electrolyte
Jul 2021
Publication
The corrosion morphology in grade 2205 duplex stainless steel wire was studied to understand the nature of pitting and the causes of the ferrite phase’s selective corrosion in acidic (pH 3) NaCl solutions at 60 °C. It is shown that the corrosion mechanism is always pitting which either manifests lacy cover perforation or densely arrayed selective cavities developing selectively on the ferrite phase. Pits with a lacy metal cover form in concentrated chloride solutions whereas the ferrite phase’s selective corrosion develops in diluted electrolytes showing dependency on the chloride-ion concentration. The pit perforation is probabilistic and occurs on both austenite and ferrite grains. The lacy metal covers collapse in concentrated solutions but remain intact in diluted electrolytes. The collapse of the lacy metal cover happens due to hydrogen embrittlement. Pit evolution is deterministic and occurs selectively in the ferrite phase in light chloride solutions.
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.
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.
Controllable H2 Generation by Formic Acid Decomposition on a Novel Pd/Templated Carbon Catalyst
Nov 2020
Publication
A novel Pd/templated carbon catalyst (Pd/TC) was developed characterized and tested in the dehydrogenation of formic acid (FA) under mild conditions with the possibility to control the H2 generation rate in the absence or presence of HCOONa (SF) by adjusting the Pd:FA and/or FA:SF ratios. The characterization results of the templated carbon obtained by the chemical vapor deposition of acetylene on NaY zeolite revealed different structural and morphological properties compared to other C-based supports. Therefore it was expected to induce a different catalytic behavior for the Pd/TC catalyst. Indeed the TC-supported Pd catalyst exhibited superior activity in the decomposition of FA even at room temperature with turnover frequencies (TOFs) of up to 143.7 and 218.8 h−1 at 60 °C. The H2 generation rate increased with an increasing temperature while the H2 yield increased with a decreasing FA concentration. Constant generation of gaseous flow (H2 + CO2) was achieved for 11 days by the complete dehydrogenation of FA at room temperature using a 2 M FA solution and Pd:FA = 1:2100. The presence of SF in the reaction medium significantly enhanced the H2 generation rate (535 h−1 for FA:SF = 3:1 and 60 °C).
NanoSIMS Analysis of Hydrogen and Deuterium in Metallic Alloys: Artefacts and Best Practice
Apr 2021
Publication
Hydrogen embrittlement can cause catastrophic failure of high strength alloys yet determining localised hydrogen in the microstructure is analytically challenging. NanoSIMS is one of the few techniques that can map hydrogen and deuterium in metal samples at microstructurally relevant length scales. Therefore it is essential to understand the artefacts and determine the optimum methodology for its reliable detection. An experimental methodology/protocol for NanoSIMS analysis of deuterium (as a proxy for hydrogen) has been established uncovering unreported artefacts and a new approach is presented to minimise these artefacts in mapping hydrogen and deuterium in alloys. This method was used to map deuterium distributions in electrochemically charged austenitic stainless steel and precipitation hardened nickel-based alloys. Residual deuterium contamination was detected in the analysis chamber as a result of deuterium outgassing from the samples and the impact of this deuterium contamination was assessed by a series of NanoSIMS experiments. A new analysis protocol was developed that involves mapping deuterium in the passive oxide layer thus mitigating beam damage effects that may prevent the detection of localised deuterium signals when the surface is highly deuterated.
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.
Formation Criterion of Hydrogen-Induced Cracking in Steel Based on Fracture Mechanics
Nov 2018
Publication
A new criterion for hydrogen-induced cracking (HIC) that includes both the embrittlement effect and the loading effect of hydrogen was obtained theoretically. The surface cohesive energy and plastic deformation energy are reduced by hydrogen atoms at the interface; thus the fracture toughness is reduced according to fracture mechanics theory. Both the pressure effect and the embrittlement effect mitigate the critical condition required for crack instability extension. During the crack instability expansion the hydrogen in the material can be divided into two categories: hydrogen atoms surrounding the crack and hydrogen molecules in the crack cavity. The loading effect of hydrogen was verified by experiments and the characterization methods for the stress intensity factor under hydrogen pressure in a linear elastic model and an elastoplastic model were analyzed using the finite-element simulation method. The hydrogen pressure due to the aggregation of hydrogen molecules inside the crack cavity regularly contributed to the stress intensity factor. The embrittlement of hydrogen was verified by electrolytic charging hydrogen experiments. According to the change in the atomic distribution during crack propagation in a molecular dynamics simulation the transition from ductile to brittle fracture and the reduction in the fracture toughness were due to the formation of crack tip dislocation regions suppressed by hydrogen. The HIC formation mechanism is both the driving force of crack propagation due to the hydrogen gas pressure and the resisting force reduced by hydrogen atoms.
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.
Evaluation of Corrosion, Mechanical Properties and Hydrogen Embrittlement of Casing Pipe Steels with Different Microstructure
Dec 2021
Publication
In the research the corrosion and mechanical properties as well as susceptibility to hydrogen embrittlement of two casing pipe steels were investigated in order to assess their serviceability in corrosive and hydrogenating environments under operation in oil and gas wells. Two carbon steels with different microstructures were tested: the medium carbon steel (MCS) with bainitic microstructure and the medium-high carbon steel (MHCS) with ferrite–pearlite microstructure. The results showed that the corrosion resistance of the MHCS in CO2-containing acid chloride solution simulating formation water was significantly lower than that of the MCS which was associated with microstructure features. The higher strength MCS with the dispersed microstructure was less susceptible to hydrogen embrittlement under preliminary electrolytic hydrogenation than the lower strength MHCS with the coarse-grained microstructure. To estimate the embrittlement of steels the method of the FEM load simulation of the specimens with cracks was used. The constitutive relations of the true stress–strain of the tested steels were defined. The stress and strain dependences in the crack tip were calculated. It was found that the MHCS was characterized by the lower plasticity on the stage of the neck formation of the specimen and the lower fracture toughness than the other one. The obtained results demonstrating the limitations of the usage of casing pipes made of the MHCS with the coarse-grained ferrite/pearlite microstructure in corrosive and hydrogenating environments were discussed.
Hydrogen Storage Behavior of TiFe Alloy Activated by Different Methods
Feb 2021
Publication
TiFe activation for hydrogen uptake was conducted through different methods and ball milling with ethanol proved to be the most effective one. TiFe alloy after activation could absorb 1.2 wt% hydrogen at room temperature with absorption and desorption plateaus of 0.5 MPa and 0.2 MPa respectively. Investigation on microstructure and chemical state of TiFe sample after milled with ethanol suggested that the well spread metallic Ti and Fe elements helped hydrogen uptake and release. The activation of TiFe alloy by milling with ethanol was achieved at ambient conditions with ease successfully and possibly can be used for large scale production
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.
Enhanced Hydrogen Storage Properties of Mg by the Synergistic Effect of Grain Refinement and NiTiO 3 Nanoparticles
May 2021
Publication
As a promising hydrogen storage material the practical application of magnesium is obstructed by the stable thermodynamics and sluggish kinetics. In this paper three kinds of NiTiO3 catalysts with different mole ratio of Ni to Ti were successfully synthesized and doped into nanocrystalline Mg to improve its hydrogen storage properties. Experimental results indicated that all the Mg-NiTiO3 composites showed prominent hydrogen storage performance. Especially the Mg-NiTiO3/TiO2 composite could take up hydrogen at room temperature and the apparent activation energy for hydrogen absorption was dramatically decreased from 69.8 ± 1.2 (nanocrystalline Mg) kJ/mol to 34.2 ± 0.2 kJ/mol. In addition the hydrogenated sample began to release hydrogen at about 193.2 °C and eventually desorbed 6.6 wt% H2. The desorption enthalpy of the hydrogenated Mg-NiTiO3 -C was estimated to be 78.6 ± 0.8 kJ/mol 5.3 kJ/mol lower compared to 83.9 ± 0.7 kJ/mol of nanocrystalline Mg. Besides the sample revealed splendid cyclic stability during 20 cycles. No obvious recession occurred in the absorption and desorption kinetics and only 0.3 wt% hydrogen capacity degradation was observed. Further structural analysis demonstrates that nanosizing and catalyst doping led to a synergistic effect on the enhanced hydrogen storage performance of Mg-NiTiO3 -C composite which might serve as a reference for future design of highly effective hydrogen storage materials.
Critical Review of Models for H2-permeation Through Polymers with Focus on the Differential Pressure Method
May 2021
Publication
To reduce loss of hydrogen in storage vessels with high energy-to-weight-ratio new materials especially polymers have to be developed as barrier materials. Very established methods for characterization of barrier materials with permeation measurements are the time-lag and flow rate method along with the differential pressure method which resembles the nature of hydrogen vessel systems very well. Long measurement durations are necessary to gain suitable measurement data for these evaluation methods and often restrictive conditions have to be fulfilled. For these reasons common models for hydrogen permeation through single-layer and multi-layer membranes as well as models for hydrogen gas properties were collected and reviewed. Using current computer power together with these models can reduce measurement time for characterization of the barrier properties of materials while additional information about the quality of the measurement results is obtained.
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.
Sizing Hydrogen Energy Storage in Consideration of Demand Response in Highly Renewable Generation Power Systems
May 2018
Publication
From an environment perspective the increased penetration of wind and solar generation in power systems is remarkable. However as the intermittent renewable generation briskly grows electrical grids are experiencing significant discrepancies between supply and demand as a result of limited system flexibility. This paper investigates the optimal sizing and control of the hydrogen energy storage system for increased utilization of renewable generation. Using a Finnish case study a mathematical model is presented to investigate the optimal storage capacity in a renewable power system. In addition the impact of demand response for domestic storage space heating in terms of the optimal sizing of energy storage is discussed. Finally sensitivity analyses are conducted to observe the impact of a small share of controllable baseload production as well as the oversizing of renewable generation in terms of required hydrogen storage size.
Hydrogen - A Sustainable Energy Carrier
Jan 2017
Publication
Hydrogen may play a key role in a future sustainable energy system as a carrier of renewable energy to replace hydrocarbons. This review describes the fundamental physical and chemical properties of hydrogen and basic theories of hydrogen sorption reactions followed by the emphasis on state-of-the-art of the hydrogen storage properties of selected interstitial metallic hydrides and magnesium hydride especially for stationary energy storage related utilizations. Finally new perspectives for utilization of metal hydrides in other applications will be reviewed.
Influence of Synthesis Gas Components on Hydrogen Storage Properties of Sodium Aluminium Hexahydride
Feb 2021
Publication
A systematic study of different ratios of CO CO2 N2 gas components on the hydrogen storage properties of the Na3AlH6 complex hydride with 4 mol% TiCl3 8 mol% aluminum and 8 mol% activated carbon is presented in this paper. The different concentrations of CO and CO2in H2 and CO CO2 N2 in H2 mixture were investigated. Both CO and CO2gas react with the complex hydride forming Al oxy-compounds NaOH and Na2CO3 that consequently cause serious decline in hydrogen storage capacity. These reactions lead to irreversible damage of complex hydride under the current experimental condition. Thus after 10 cycles with 0.1 vol % CO + 99.9 vol %H2 and 1 vol % CO + 99 vol %H2 the dehydrogenation storage capacity of the composite material decreased by 17.2% and 57.3% respectively. In the case of investigation of 10 cycles with 1 vol % CO2 + 99 vol % H2 gas mixture the capacity degradation was 53.5%. After 2 cycles with 10 vol % CO +90 vol % H2 full degradation was observed whereas after 6 cycles with 10 vol % CO2+ 90 vol % H2 degradation of 86.8% was measured. While testing with the gas mixture of 1.5 vol % CO + 10 vol % CO2+ 27 vol % H2 + 61.5 vol % N2 the degradation of 94% after 6 cycles was shown. According to these results it must be concluded that complex aluminum hydrides cannot be used for the absorption of hydrogen from syngas mixtures without thorough purification.
Hydrogen Embrittlement and Oxide Layer Effect in the Cathodically Charged Zircaloy-2
Apr 2020
Publication
Poland The present paper is aimed at determining the less investigated effects of hydrogen uptake on the microstructure and the mechanical behavior of the oxidized Zircaloy-2 alloy. The specimens were oxidized and charged with hydrogen. The different oxidation temperatures and cathodic current densities were applied. The scanning electron microscopy X-ray electron diffraction spectroscopy hydrogen absorption assessment tensile and nanoindentation tests were performed. At low oxidation temperatures an appearance of numerous hydrides and cracks and a slight change of mechanical properties were noticed. At high-temperature oxidation the oxide layer prevented the hydrogen deterioration of the alloy. For nonoxidized samples charged at different current density nanoindentation tests showed that both hardness and Young’s modulus revealed the minims at specific current value and the stepwise decrease in hardness during hydrogen desorption. The obtained results are explained by the barrier effect of the oxide layer against hydrogen uptake softening due to the interaction of hydrogen and dislocations nucleated by indentation test and hardening caused by the decomposition of hydrides. The last phenomena may appear together and result in hydrogen embrittlement in forms of simultaneous hydrogen-enhanced localized plasticity and delayed hydride cracking.
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.
Validation of Selected Optical Methods for Assessing Polyethylene (PE) Liners Used in High Pressure Vessels for Hydrogen Storage
Jun 2021
Publication
A polyethylene (PE) liner is the basic element in high-pressure type 4 composite vessels designed for hydrogen or compressed natural gas (CNG) storage systems. Liner defects may result in the elimination of the whole vessel from use which is very expensive both at the manufacturing and exploitation stage. The goal is therefore the development of efficient non-destructive testing (NDT) methods to test a liner immediately after its manufacturing before applying a composite reinforcement. It should be noted that the current regulations codes and standards (RC&S) do not specify liner testing methods after manufacturing. It was considered especially important to find a way of locating and assessing the size of air bubbles and inclusions and the field of deformations in liner walls. It was also expected that these methods would be easily applicable to mass-produced liners. The paper proposes the use of three optical methods namely visual inspection digital image correlation (DIC) and optical fiber sensing based on Bragg gratings (FBG). Deformation measurements are validated with finite element analysis (FEA). The tested object was a prototype of a hydrogen liner for high-pressure storage (700 bar). The mentioned optical methods were used to identify defects and measure deformations.
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