Transmission, Distribution & Storage

Hydrogen as an energy carrier is very versatile in energy storage applications. Developments in novel sustainable technologies towards a CO2-free society are needed and the exploration of all-solid-state batteries (ASSBs) as well as solid-state hydrogen storage applications based on metal hydrides can provide solutions for such technologies. However there are still many technical challenges for both hydrogen storage material and ASSBs related to designing low-cost materials with low-environmental impact. The current materials considered for all-solid-state batteries should have high conductivities for Na+ Mg2+ and Ca2+ while Al3+-based compounds are often marginalised due to the lack of suitable electrode and electrolyte materials. In hydrogen storage materials the sluggish kinetic behaviour of solid-state hydride materials is one of the key constraints that limit their practical uses. Therefore it is necessary to overcome the kinetic issues of hydride materials before discussing and considering them on the system level. This review summarizes the achievements of the Marie Skłodowska-Curie Actions (MSCA) innovative training network (ITN) ECOSTORE the aim of which was the investigation of different aspects of (complex) metal hydride materials. Advances in battery and hydrogen storage materials for the efficient and compact storage of renewable energy production are discussed.

Hydrogen has been identified as a very promising vector for energy storage especially for heavy mobility applications. For this reason France is making significant investments in this field and use cases need to be evaluated as they are sprouting. In this paper the relevance of H2 in two storage applications is studied: a domestic renewable electricity production system connected to the grid and a collective hydrogen production for the daily bus refill. The investigation consists of the sizing of the system and then the evaluation of its performance according to several criteria depending on case. Optimizations are made using Bayesian and gradient-based methods. Several variations around a central case are explored for both cases to give insights on the impact of the different parameters (location pricing objective etc.) on the performance of the system.Our results show that domestic power-to-power applications (case 1) do not seem to be competitive with electrochemical storage. Meanwhile without any subsidies or incentives such configuration does not allow prosumers to save money (+16% spendings compared to non-equipped dwelling). It remains interesting when self-sufficiency is the main objective (up to 68% of energy is not exchanged). The power-to-gas application (case 2 central case) with a direct use of hydrogen for mobility seems to be more relevant according to our case study we could reach a production cost of green H2 around 5 €/kg similar to the 3–10 $/kg found in literature for 182 houses involved. In both cases H2 follows a yearly cycle charging in summer and discharging in winter (long term storage) due to low conversion efficiency.

Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Although in the last 15 years a large variety of material systems have been identified as possible candidates for storing hydrogen further efforts have to be made in the development of systems which meet the strict targets of the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and U.S. Department of Energy (DOE). Recent projections indicate that a system possessing: (i) an ideal enthalpy in the range of 20–50 kJ/mol H2 to use the heat produced by PEM fuel cell for providing the energy necessary for desorption; (ii) a gravimetric hydrogen density of 5 wt. % H2 and (iii) fast sorption kinetics below 110 ◦C is strongly recommended. Among the known hydrogen storage materials amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however some barriers still have to be overcome before considering this class of material mature for real applications. In this review the most relevant progresses made in the recent years as well as the kinetic and thermodynamic properties experimentally measured for the most promising systems are reported and properly discussed.

Technology safety represents a key enabling factor for the commercial use of hydrogen within the automotive industry. In the last years considerable pre-normative and normative research effort has produced regulations at national European and global level as well as international standards. Their validation is at the moment on going internationally. Additional research is required to improve this regulatory and standardization frame which is also expected to have a beneficial effect on cost and product optimization. The present paper addresses results related to the experimental assessment and modeling of safety performance of high pressure onboard storage. To simulate the lifetime of onboard hydrogen tanks commercial tanks have been subjected to filling-emptying cycles encompassing a fast-filling phase as prescribed by the European regulation on type-approval of hydrogen vehicles. The local temperature history inside the tanks has been measured and compared with the temperature outside at the tank metallic bosses which is the measurement location identified by the regulation. Experimental activities are complemented by computational fluid-dynamics (CFD) modeling of the fast-filling process by means of a numerical model previously validated. The outcome of these activities is a set of scientifically based data which will serve as input to future regulations and standards improvement.

This paper reviews state-of-the-art developments in hydrogen energy systems which integrate fuel cells with metal hydride-based hydrogen storage. The 187 reference papers included in this review provide an overview of all major publications in the field as well as recent work by several of the authors of the review. The review contains four parts. The first part gives an overview of the existing types of fuel cells and outlines the potential of using metal hydride stores as a source of hydrogen fuel. The second part of the review considers the suitability and optimisation of different metal hydrides based on their energy efficient thermal integration with fuel cells. The performances of metal hydrides are considered from the viewpoint of the reversible heat driven interaction of the metal hydrides with gaseous H2. Efficiencies of hydrogen and heat exchange in hydrogen stores to control H2 charge/discharge flow rates are the focus of the third section of the review and are considered together with metal hydride – fuel cell system integration issues and the corresponding engineering solutions. Finally the last section of the review describes specific hydrogen-fuelled systems presented in the available reference data.

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.

Hydrogen storage in nanoporous materials has been attracting a great deal of attention in recent years as high gravimetric H2 capacities exceeding 10 wt% in some cases can be achieved at 77 K using materials with particularly high surface areas. However volumetric capacities at low temperatures and both gravimetric and volumetric capacities at ambient temperature need to be improved before such adsorbents become practically viable. This article therefore discusses approaches to increasing the gravimetric and volumetric hydrogen storage capacities of nanoporous materials and maximizing the usable capacity of a material between the upper storage and delivery pressures. In addition recent advances in machine learning and data science provide an opportunity to apply this technology to the search for new materials for hydrogen storage. The large number of possible component combinations and substitutions in various porous materials including Metal-Organic Frameworks (MOFs) is ideally suited to a machine learning approach; so this is also discussed together with some new material types that could prove useful in the future for hydrogen storage applications.

This is a transcript of the discussion session on the effects of hydrogen in the non-ferrous alloys of zirconium and titanium which are anisotropic hydride-forming metals. The four talks focus on the hydrogen embrittlement mechanisms that affect zirconium and titanium components which are respectively used in the nuclear and aerospace industries. Two specific mechanisms are delayed hydride cracking and stress corrosion cracking.

This article is a transcription of the recorded discussion of the session ‘Hydrogen in non-ferrous alloys’ at the Royal Society Discussion Meeting Challenges of Hydrogen in Metals 16–18 January 2017. The text is approved by the contributors. M.P. transcribed the session. M.A.S. assisted in the preparation of the manuscript.

Link to document download on Royal Society Website 

Hydrogen has become a strong candidate to be a future energy storage medium but there are technological challenges both in its production and storage. For storage a search for lightweight abundant and non-toxic materials is on the way. An abundant natural material such as wood cellulose would make an ideal storage medium from a sustainability perspective. Here using a combination of static DFT calculations and ab initio molecular dynamics simulations at different temperatures it is shown that wood cellulose has the ability to uptake H2 via a physisorption mechanism based on dispersion interactions of the van der Waals type involving the O-atoms of the d-glucose rings. The absorption causes little to no disturbances on the cellulose structure and H2 is highly mobile in the material. At an external pressure of H2(g) of 0.09 atm and T = 25 °C cellulose has a theoretical gravimetric density of hydrogen storage of ≈1%.

Melt spinning was successfully utilized to prepare Mg₂₅−_xY_xNi₉Cu (x = 0 1 3 5 7) alloys producing nanocrystalline and amorphous structures with improved hydrogenation and dehydrogenation performances. The influence of spinning rate on hydrogenation and dehydrogenation thermodynamics and kinetics was studied in detail. XRD and TEM were utilized to characterize the alloy structures. Hydrogenation and dehydrogenation performances were investigated by Sievert apparatus DSC and TGA connected to a H₂ detector. Dehydrogenation activation energies were estimated using both Arrhenius and Kissinger methods. Results show that melt spinning significantly decreases thermodynamic parameters (ΔH and ΔS) and ameliorates desorption kinetics. Dehydrogenation activation energy markedly lowers with increase in spinning rate and is the real driver of amelioration of dehydrogenation kinetics caused by increasing Y content.

The final session of the meeting consisted of a discussion panel to propose future directions for research in the field of hydrogen embrittlement and the potential impact of this research on public policy.

This article is a transcription of the recorded discussion of ‘Hydrogen Embrittlement: Future Directions’ at the Royal Society Scientific Discussion Meeting Challenges of Hydrogen and Metals Jan 16th–18th 2017. The text is approved by the contributors. H.L. transcribed the session and drafted the manuscript. Y.C. assisted in the preparation of the manuscript.

Link to document download on Royal Society Website 

V-Nb-Mo-Ta-W high-entropy alloy (HEA) one of the refractory HEAs is considered as a next-generation structural material for ultra-high temperature uses. Refractory HEAs have low castability and machinability due to their high melting temperature and low thermal conductivity. Thus powder metallurgy becomes a promising method for fabricating components with refractory HEAs. Therefore in this study we fabricated spherical V-Nb-Mo-Ta-W HEA powder using hydrogen embrittlement and spheroidization by thermal plasma. The HEA ingot was prepared by vacuum arc melting and revealed to have a single body-centered cubic phase. Hydrogen embrittlement which could be achieved by annealing in a hydrogen atmosphere was introduced to get the ingot pulverized easily to a fine powder having an angular shape. Then the powder was annealed in a vacuum atmosphere to eliminate the hydrogen from the hydrogenated HEA resulting in a decrease in the hydrogen concentration from 0.1033 wt% to 0.0003 wt%. The angular shape of the HEA powder was turned into a spherical one by inductively-coupled thermal plasma allowing to fabricate spherical V-Nb-Mo-Ta-W HEA powder with a d50 value of 28.0 μm.

Transition metal carbides are a class of materials widely known for both their interesting physical properties and catalytic activity. In this work we have used plane-wave DFT methods to study the interaction with increasing amounts of molecular hydrogen on the low-index surfaces of four major carbides – TiC VC ZrC and NbC. Adsorption is found to be generally exothermic and occurs predominantly on the surface carbon atoms. We identify trends over the carbides and their surfaces for the energetics of the adsorption as a function of their electronic and geometrical characteristics. An ab initio thermodynamics formalism is used to study the properties of the slabs as the hydrogen coverage is increased.

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.

Efficient energy production and consumption are fundamental points for reducing carbon emissions that influence climate change. Alternative resources such as renewable energy sources (RESs) used in electricity grids could reduce the environmental impact. Since RESs are inherently unreliable during the last decades the scientific community addressed research efforts to their integration with the main grid by means of properly designed energy storage systems (ESSs). In order to highlight the best performance from these hybrid systems proper design and operations are essential. The purpose of this paper is to present a so-called model predictive controller (MPC) for the optimal operations of grid-connected wind farms with hydrogen-based ESSs and local loads. Such MPC has been designed to take into account the operating and economical costs of the ESS the local load demand and the participation to the electricity market and further it enforces the fulfillment of the physical and the system's dynamics constraints. The dynamics of the hydrogen-based ESS have been modeled by means of the mixed-logic dynamic (MLD) framework in order to capture different behaviors according to the possible operating modes. The purpose is to provide a controller able to cope both with all the main physical and operating constraints of a hydrogen-based storage system including the switching among different modes such as ON OFF STAND-BY and at the same time reduce the management costs and increase the equipment lifesaving. The case study for this paper is a plant under development in the north Norway. Numerical analysis on the related plant data shows the effectiveness of the proposed strategy which manages the plant and commits the equipment so as to preserve the given constraints and save them from unnecessary commutation cycles.

Hydrogen injection into the GB gas network is a likely consequence of using excess offshore wind generated electricity to power large-scale onshore electrolysis plants. Government and DECC in particular now have a keen interest in supporting technologies that can take advantage of the continued use of the gas networks. HSE can contribute to the government’s Growth and Green agendas by effectively regulating and safely enabling this technology.

This report will allow HSE to regulate effectively by pulling together scientific and engineering knowledge regarding the hazards of conveying hydrogen/methane mixtures in network pipes and its use in consumer appliances into a single ‘state-of-play’ report. It enables Energy Division to consider and assess submissions for ‘gas quality’ exemptions to the Gas Safety (Management) Regulations 1996 (GSMR).

In particular the report has examined the following hazards:

• conveyance of H2/CH4 mixtures in network pipes
• use of H2/CH4 mixtures in consumer appliances (domestic/commercial/industrial)
• explosion and damage characteristics (and ignition likelihood) of H2/CH4 mixtures
• effects on odourisation

It identifies that the flame profile in gas appliances will increasingly flatten as hydrogen content rises. For modern appliances fitted with flame failure devices this may cause the appliance to shut down (and default to a safe condition). For some older types of gas appliance (1970s and older) not fitted with flame failure devices there may be an increased risk of flame failure leading to internal gas escapes. At the concentrations of hydrogen in methane likely to be considered by the industry (between 0.5 and 10%) this effect is not significant. Where exemptions for higher concentrations are sought HSE will insist on the identification and modification of vulnerable appliances. The report concludes that concentrations of hydrogen in methane of up to 20% by volume are unlikely to increase risk from within the gas network for from gas appliances to consumers or members of the public.

The deployment of diverse energy storage technologies with the combination of daily weekly and seasonal storage dynamics allows for the reduction of carbon dioxide (CO₂) emissions per unit energy provided. In particular the production storage and re-utilization of hydrogen starting from renewable energy has proven to be one of the most promising solutions for offsetting seasonal mismatch between energy generation and consumption. A realistic possibility for large-scale hydrogen storage suitable for long-term storage dynamics is presented by salt caverns. In this contribution we provide a framework for modelling underground hydrogen storage with a focus on salt caverns and we evaluate its potential for reducing the CO₂ emissions within an integrated energy systems context. To this end we develop a first-principle model which accounts for the transport phenomena within the rock and describes the dynamics of the stored energy when injecting and withdrawing hydrogen. Then we derive a linear reduced order model that can be used for mixed-integer linear program optimization while retaining an accurate description of the storage dynamics under a variety of operating conditions. Using this new framework we determine the minimum-emissions design and operation of a multi-energy system with H₂ storage. Ultimately we assess the potential of hydrogen storage for reducing CO₂ emissions when different capacities for renewable energy production and energy storage are available mapping emissions regions on a plane defined by storage capacity and renewable generation. We extend the analysis for solar- and wind-based energy generation and for different energy demands representing typical profiles of electrical and thermal demands and different CO₂ emissions associated with the electric grid.

A solid-state hydrogen storage material comprising ammonia borane (AB) and polyethylene oxide (PEO) has been produced by freeze-drying from aqueous solutions from 0% to 100% AB by mass. The phase mixing behaviour of AB and PEO has been investigated using X-ray diffraction which shows that a new ‘intermediate’ crystalline phase exists different from both AB and PEO as observed in our previous work (Nathanson et al. 2015). It is suggested that hydrogen bonding interactions between the ethereal oxygen atom (–O–) in the PEO backbone and the protic hydrogen atoms attached to the nitrogen atom (N–H) of AB molecules promote the formation of a reaction intermediate leading to lowered hydrogen release temperatures in the composites compared to neat AB. PEO also acts to significantly reduce the foaming of AB during hydrogen release. A temperature-composition phase diagram has been produced for the AB-PEO system to show the relationship between phase mixing and hydrogen release.

The safety and convenience of hydrogen storage are significant for fuel cell vehicles. Based on mass conservation equation and energy conservation equation two thermodynamic models (single zone model and dual zone model) have been established to study the hydrogen gas temperature and tank wall temperature for compressed hydrogen storage tank. With two models analytical solution and Euler solution for single zone (gas zone) charge-discharge cycle have been compared Matlab/Simulink solution and Euler solution for dual zone (gas zone wall zone) charge-discharge cycle have been compared. Three charge-discharge cycle cases (Case 1 constant inflow temperature; Case 2 variable inflow temperature; Case 3 constant inflow temperature variable outflow temperature) and two compressed hydrogen tanks (Type III 25L Type IV 99L) charge-discharge cycle are studied by Euler method. Results show Euler method can well predict hydrogen temperature and tank wall temperature.

In this study YMg₁₁Ni and YMg₁₁Ni + 5 wt% MoS₂ (named YMg11Ni–MoS₂) alloys were prepared by mechanical milling to examine the effect of adding MoS₂ on the hydrogen storage performance of a Y–Mg–Ni-based alloy. The as-cast and milled alloys were tested to identify their structures by X-ray diffraction and transmission electron microscopy. The isothermal hydrogen storage thermodynamics and dynamics were identified through an automatic Sieverts apparatus and the non-isothermal dehydrogenation performance was investigated by thermogravimetry and differential scanning calorimetry. The dehydrogenation activation energy was calculated by both Arrhenius and Kissinger methods. Results revealed that adding MoS₂produces a very slight effect on hydrogen storage thermodynamics but causes an obvious reduction in the hydrogen sorption and desorption capacities because of the deadweight of MoS_2. The addition of MoS₂significantly enhances the dehydrogenation performance of the alloy such as lowering dehydrogenation temperature and enhancing dehydrogenation rate. Specifically the initial desorption temperature of the alloy hydride lowers from 549.8 K to 525.8 K. The time required to desorb hydrogen at 3 wt% H₂ is 1106 456 363 and 180 s corresponding to hydrogen desorption temperatures at 593 613 633 and 653 K for the YMg₁₁Ni alloy and 507 208 125 and 86 s at identical conditions for the YMg₁₁Ni–5MoS₂ alloy. The dehydrogenation activation energy (E_a) values with and without added MoS₂are 85.32 and 98.01 kJ mol⁻¹. Thus a decrease in E_a value by 12.69 kJ mol−1 occurs and is responsible for the amelioration of the hydrogen desorption dynamics by adding a MoS₂ catalyst.

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.

The study of steels which guarantee safety and reliability throughout their service life in hydrogen-rich environments has increased considerably in recent years. Their mechanical behavior in terms of hydrogen embrittlement is of utmost importance. This work aims to assess the effects of hydrogen on the tensile properties of quenched and tempered 42CrMo4 steels. Tensile tests were performed on smooth and notched specimens under different conditions: pre-charged in high pressure hydrogen gas electrochemically pre-charged and in-situ hydrogen charged in an acid aqueous medium. The influence of the charging methodology on the corresponding embrittlement indexes was assessed. The role of other test variables such as the applied current density the electrolyte composition and the displacement rate was also studied. An important reduction of the strength was detected when notched specimens were subjected to in-situ charging. When the same tests were performed on smooth tensile specimens the deformation results were reduced. This behavior is related to significant changes in the operative failure micromechanisms from ductile (microvoids coalescence) in absence of hydrogen or under low hydrogen contents to brittle (decohesion of martensite lath interfaces) under the most stringent conditions.

The utilization of power to gas technologies to store renewable electricity surpluses in the form of hydrogen enables the integration of the gas and electricity sectors allowing the decarbonization of the natural gas network through green hydrogen injection. Nevertheless the injection of significant amounts of hydrogen may lead to high local concentrations that may degrade materials (e.g. hydrogen embrittlement of pipelines) and in general be not acceptable for the correct and safe operation of appliances. Most countries have specific regulations to limit hydrogen concentration in the gas network. The methanation of hydrogen represents a potential option to facilitate its injection into the grid. However stoichiometric methanation will lead to a significant presence of carbon dioxide limited in gas networks and requires an accurate design of several reactors in series to achieve relevant concentrations of methane. These requirements are smoothed when the methanation is undertaken under non-stoichiometric conditions (high H/C ratio). This study aims to assess to influence of nonstoichiometric methanation under different H/C ratios on the limitations presented by the pure hydrogen injection. The impact of this injection on the operation of the gas network at local level has been investigated and the fluid-dynamics and the quality of gas blends have been evaluated. Results show that non-stoichiometric methanation could be an alternative to increase the hydrogen injection in the gas network and facilitates the gas and electricity sector coupling.

The ultrafine-grained (UFG) duplex microstructure of medium-Mn steel consists of a considerable amount of austenite and ferrite/martensite achieving an extraordinary balance of mechanical properties and alloying cost. In the present work two heat treatment routes were performed on a cold-rolled medium-Mn steel Fe-12Mn-3Al-0.05C (wt.%) to achieve comparable mechanical properties with different microstructural morphologies. One heat treatment was merely austenite-reverted-transformation (ART) annealing and the other one was a successive combination of austenitization (AUS) and ART annealing. The distinct responses to hydrogen ingression were characterized and discussed. The UFG martensite colonies produced by the AUS + ART process were found to be detrimental to ductility regardless of the amount of hydrogen which is likely attributed to the reduced lattice bonding strength according to the H-enhanced decohesion (HEDE) mechanism. With an increase in the hydrogen amount the mixed microstructure (granular + lamellar) in the ART specimen revealed a clear embrittlement transition with the possible contribution of HEDE and H-enhanced localized plasticity (HELP) mechanisms.

Improving efficiency of hydrogen cooling in cryogenic conditions is important for the wider applications of hydrogen energy systems. The approach investigated in this study is based on a Ranque-Hilsch vortex tube (RHVT) that generates temperature separation in a working fluid. The simplicity of RHVT is also a valuable characteristic for cryogenic systems. In the present work novel shapes of RHVT are computationally investigated with the goal to raise efficiency of the cooling process. Specifically a smooth transition is arranged between a vortex chamber where compressed gas is injected and the main tube with two exit ports at the tube ends. Flow simulations have been carried out using STAR-CCM+ software with the real-gas Redlich-Kwong model for hydrogen at temperatures near 70 K. It is determined that a vortex tube with a smooth transition of moderate size manifests about 7% improvement of the cooling efficiency when compared vortex tubes that use traditional vortex chambers with stepped transitions and a no-chamber setup with direct gas injection.

Hypothesis: Hydrogen geo-storage is considered as an option for large scale hydrogen storage in a full-scale hydrogen economy. Among different types of subsurface formations coal seams look to be one of the best suitable options as coal’s micro/nano pore structure can adsorb a huge amount of gas (e.g. hydrogen) which can be withdrawn again once needed. However literature lacks fundamental data regarding H2 diffusion in coal. Experiments: In this study we measured H2 adsorption rate in an Australian anthracite coal sample at isothermal conditions for four different temperatures (20 C 30 C 45 C and 60 C) at equilibrium pressure 13 bar and calculated H2 diffusion coefficient (DH2 ) at each temperature. CO2 adsorption rates were measured for the same sample at similar temperatures and equilibrium pressure for comparison. Findings: Results show that H2 adsorption rate and consequently DH2 increases by temperature. DH2 values are one order of magnitude larger than the equivalent DCO2 values for the whole studied temperature range 20–60 C. DH2 / DCO2 also shows an increasing trend versus temperature. CO2 adsorption capacity at equilibrium pressure is about 5 times higher than that of H2 in all studied temperatures. Both H2 and CO2 adsorption capacities at equilibrium pressure slightly decrease as temperature rises.

The paper presents and discusses results of mechanical spectroscopy (MS) tests carried out on a Cr martensitic steel. The study regards the following topics: (i) embrittlement induced by Cr segregation; (ii) interaction of hydrogen with C–Cr associates; (iii) nucleation of Cr carbides. The MS technique permitted characterising of the specific role played by point defects in the investigated phenomena: (i) Cr segregation depends on C–Cr associates distribution in as-quenched material in particular a slow cooling rate (~150 K/min) from austenitic field involves an unstable distribution which leads to Cr concentration fluctuations after tempering at 973 K; (ii) hydrogen interacts with C–Cr associates and the phenomenon hinders hydrogen attack (HA) because hydrogen atoms bound by C–Cr associates are not able to diffuse towards grain boundaries and dislocation where CH4 bubbles may nucleate grow and merge to form the typical HA cracks; (iii) C–Cr associates take part in the nucleation mechanism of Cr7C3 carbides and specifically these carbides form by the aggregation of C–Cr associates with 1 Cr atom.

This work focuses in investigating the effect of cold deformation on the cathodic hydrogen charging of 5083 aluminum alloy. The aluminium alloy was submitted to a cold rolling process until the average thickness of the specimens was reduced by 7% and 15% respectively. A study of the structure microhardness and tensile properties of the hydrogen charged aluminium specimens with and without cold rolling indicated that the cold deformation process led to an increase of hydrogen susceptibility of this aluminum alloy.

Carbon capture and storage (CCS) refers to a set of technologies that may offer the potential for large-scale removal of CO₂ emissions from a range of processes – potentially including the generation of electricity and heat industrial processes and the production of hydrogen and synthetic fuels. CCS has both proponents and opponents. Like other emerging low carbon technologies CCS is not without risks or uncertainties and there are various challenges that would need to be overcome if it were to be widely deployed. Policy makers’ decisions as to whether to pursue CCS should be based on a judgement as to whether the risks and uncertainties associated with attempting to deploy CCS outweigh the risks of not having it available as part of a portfolio of mitigation options in future years.

The full report can be found on the Global CSS Institute website at this link

Precipitation hardenable (PH) nickel (Ni) alloys are often the most reliable engineering materials for demanding oilfield upstream and subsea applications especially in deep sour wells. Despite their superior corrosion resistance and mechanical properties over a broad range of temperatures the applicability of PH Ni alloys has been questioned due to their susceptibility to hydrogen embrittlement (HE) as confirmed in documented failures of components in upstream applications. While extensive work has been done in recent years to develop testing methodologies for benchmarking PH Ni alloys in terms of their HE susceptibility limited scientific research has been conducted to achieve improved foundational knowledge about the role of microstructural particularities in these alloys on their mechanical behaviour in environments promoting hydrogen uptake. Precipitates such as the γ′ γ′′ and δ-phase are well known for defining the mechanical and chemical properties of these alloys. To elucidate the effect of precipitates in the microstructure of the oil-patch PH Ni alloy 718 on its HE susceptibility slow strain rate tests under continuous hydrogen charging were conducted on material after several different age-hardening treatments. By correlating the obtained results with those from the microstructural and fractographic characterization it was concluded that HE susceptibility of oil-patch alloy 718 is strongly influenced by the amount and size of precipitates such as the γ′ and γ′′ as well as the δ-phase rather than by the strength level only. In addition several HE mechanisms including hydrogen-enhanced decohesion and hydrogen-enhanced local plasticity were observed taking place on oil-patch alloy 718 depending upon the characteristics of these phases when present in the microstructure.

Link to document download on Royal Society Website

The objective of this study is to analyze a government proposal from a panoramic perspective concerning the economic and environmental effects associated with the construction and operation of hydrogen utilization systems by the year 2030. We focused on a marine transport system for hydrogen produced offshore hydrogen gas turbine power generation fuel cell vehicles (FCVs) and hydrogen stations as well as residential fuel cell systems (RFCs). In this study using an Input-Output Table for Next Generation Energy Systems (IONGES) we evaluated the induced output labor and CO2 emissions from the construction and operation of these hydrogen technologies using a uniform approach. This may be helpful when considering future designs for the Japanese energy system. In terms of per 1 t-H2 of hydrogen use CO2 reductions from the use of FCVs are considerably higher than the additional CO2 emissions from foreign production and transportation of hydrogen. Because new construction of a hydrogen pipeline network is not considered to be realistic RFCs is assumed to consume hydrogen generated by refining town gas. In this case the CO2 reductions from using RFCs will decline under the electricity composition estimated for 2030 on the condition of a substantial expansion of electricity generation from renewable energy sources. However under the present composition of electricity production we can expect a certain amount of CO2 reductions from using RFCs. If hydrogen is directly supplied to RFCs CO2 reductions increase substantially. Thus we can reduce a significant amount of CO2 emissions if various unused energy sources dispersed around local areas or unharnessed renewable energies such as solar and wind power can be converted into hydrogen to be supplied to FCVs and RFCs.

We investigated hydrogen embrittlement in Fe20Mn20Ni20Cr20Co and Fe30Mn10Cr10Co (at.%) alloys pre-charged with 100 MPa hydrogen gas by tensile testing at three initial strain rates of 10⁻⁴ 10⁻³ and 10⁻² s⁻¹ at ambient temperature. The alloys are classified as stable and metastable austenite-based high-entropy alloys (HEAs) respectively. Both HEAs showed the characteristic hydrogen-induced degradation of tensile ductility. Electron backscatter diffraction analysis indicated that the reduction in ductility by hydrogen pre-charging was associated with localized plasticity-assisted intergranular crack initiation. It should be noted as an important finding that hydrogen-assisted cracking of the metastable HEA occurred not through a brittle mechanism but through localized plastic deformation in both the austenite and ε-martensite phases.

Metal hydrides are known as a potential efficient low-risk option for high-density hydrogen storage since the late 1970s. In this paper the present status and the future perspectives of the use of metal hydrides for hydrogen storage are discussed. Since the early 1990s interstitial metal hydrides are known as base materials for Ni – metal hydride rechargeable batteries. For hydrogen storage metal hydride systems have been developed in the 2010s [1] for use in emergency or backup power units i. e. for stationary applications.<br/>With the development and completion of the first submarines of the U212 A series by HDW (now Thyssen Krupp Marine Systems) in 2003 and its export class U214 in 2004 the use of metal hydrides for hydrogen storage in mobile applications has been established with new application fields coming into focus.<br/>In the last decades a huge number of new intermetallic and partially covalent hydrogen absorbing compounds has been identified and partly more partly less extensively characterized.<br/>In addition based on the thermodynamic properties of metal hydrides this class of materials gives the opportunity to develop a new hydrogen compression technology. They allow the direct conversion from thermal energy into the compression of hydrogen gas without the need of any moving parts. Such compressors have been developed and are nowadays commercially available for pressures up to 200 bar. Metal hydride based compressors for higher pressures are under development. Moreover storage systems consisting of the combination of metal hydrides and high-pressure vessels have been proposed as a realistic solution for on-board hydrogen storage on fuel cell vehicles.<br/>In the frame of the “Hydrogen Storage Systems for Mobile and Stationary Applications” Group in the International Energy Agency (IEA) Hydrogen Task 32 “Hydrogen-based energy storage” different compounds have been and will be scaled-up in the near future and tested in the range of 500 g to several hundred kg for use in hydrogen storage applications.

Hydrogen technologies have been rapidly developing in the past few decades pushed by governments’ road maps for sustainability and supported by a widespread need to decarbonize the global energy sector. Recent scientific progress has led to better performances and higher efficiencies of hydrogen-related technologies so much so that their future economic viability is now rarely called into question. This article intends to study the integration of hydrogen systems in both gas and electric distribution networks. A preliminary analysis of hydrogen’s physical storage methods is given considering both the advantages and disadvantages of each one. After examining the preeminent ways of physically storing hydrogen this paper then contemplates two primary means of using it: integrating it in Power-to-Gas networks and utilizing it in Power-to-Power smart grids. In the former the primary objective is the total replacement of natural gas with hydrogen through progressive blending procedures from the transmission pipeline to the domestic burner; in the latter the set goal is the expansion of the implementation of hydrogen systems—namely storage—in multi-microgrid networks thus helping to decarbonize the electricity sector and reducing the impact of renewable energy’s intermittence through Demand Side Management strategies. The study concludes that hydrogen is assumed to be an energy vector that is inextricable from the necessary transition to a cleaner more efficient and sustainable future.

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 problem of hydrogen embrittlement in ultra-high-strength steels is well known. In this study slow strain rate four-point bending and permeation tests were performed with the aim of characterizing innovative materials with an ultimate tensile strength higher than 1000 MPa. Hydrogen uptake in the case of automotive components can take place in many phases of the manufacturing process: during hot stamping due to the presence of moisture in the furnace atmosphere high-temperature dissociation giving rise to atomic hydrogen or also during electrochemical treatments such as cataphoresis. Moreover possible corrosive phenomena could be a source of hydrogen during an automobile’s life. This series of tests was performed here in order to characterize two press-hardened steels (PHS)—USIBOR 1500® and USIBOR 2000®—to establish a correlation between ultimate mechanical properties and critical hydrogen concentration.

Strain-induced martensite transformation (SIMT) commonly exists around a crack tip of metastable austenite stainless steels. The influence of the volume expansion of the SIMT on the hydrogen diffusion was investigated by hydrogen diffusion modelling around a crack tip in type 304L austenite stainless steel. The volume expansion changed the tensile stress state into pressure stress state at the crack tip resulting in a large stress gradient along the crack propagation direction. Compared to the analysis without considering the volume expansion effect this volume expansion further accelerated the hydrogen transport from the inner surface to a critical region ahead of the crack tip and further increased the maximum value of the hydrogen concentration at the critical position where the strain-induced martensite fraction approximates to 0.1 indicating that the volume expansion of the SIMT further increased the hydrogen embrittlement susceptibility.

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.

The integration and control of energy systems for power generation consists of multiple heterogeneous subsystems such as chemical electrochemical and thermal and contains challenges that arise from the multi-way interactions due to complex dynamic responses among the involved subsystems. The main motivation of this work is to design the control system for an autonomous automated and sustainable system that meets a certain power demand profile. A systematic methodology for the integration and control of a hybrid system that converts liquefied petroleum gas (LPG) to hydrogen which is subsequently used to generate electrical power in a high-temperature fuel cell that charges a Li-Ion battery unit is presented. An advanced nonlinear model predictive control (NMPC) framework is implemented to achieve this goal. The operational objective is the satisfaction of power demand while maintaining operation within a safe region and ensuring thermal and chemical balance. The proposed NMPC framework based on experimentally validated models is evaluated through simulation for realistic operation scenarios that involve static and dynamic variations of the power load.

An update on the proposed commercial frameworks for transport and storage power and industrial carbon capture business models.

A study was performed to investigate the hydrogen embrittlement behavior of 18-Ni 300 maraging steel produced by selective laser melting and subjected to different heat treatment strategies. Hydrogen was pre-charged into the tensile samples by an electro-chemical method at the constant current density of 1 A m−2 and 50 A m−2 for 48 h at room temperature. Charged and uncharged specimens were subjected to tensile tests and the hydrogen concentration was eventually analysed using quadrupole mass spectroscopy. After tensile tests uncharged maraging samples showed fracture surfaces with dimples. Conversely in H-charged alloys quasi-cleavage mode fractures occurred. A lower concentration of trapped hydrogen atoms and higher elongation at fracture were measured in the H-charged samples that were subjected to solution treatment prior to hydrogen charging compared to the as-built counterparts. Isothermal aging treatment performed at 460 °C for 8 h before hydrogen charging increased the concentration of trapped hydrogen giving rise to higher hydrogen embrittlement susceptibility.

A potential enabler of a low carbon economy is the energy vector hydrogen. However issues associated with hydrogen storage and distribution are currently a barrier for its implementation. Hence other indirect storage media such as ammonia and methanol are currently being considered. Of these ammonia is a carbon free carrier which offers high energy density; higher than compressed air. Hence it is proposed that ammonia with its established transportation network and high flexibility could provide a practical next generation system for energy transportation storage and use for power generation. Therefore this review highlights previous influential studies and ongoing research to use this chemical as a viable energy vector for power applications emphasizing the challenges that each of the reviewed technologies faces before implementation and commercial deployment is achieved at a larger scale. The review covers technologies such as ammonia in cycles either for power or CO₂ removal fuel cells reciprocating engines gas turbines and propulsion technologies with emphasis on the challenges of using the molecule and current understanding of the fundamental combustion patterns of ammonia blends.

The aim of this work is to study the effect of the displacement rate on the hydrogen embrittlement of two different structural steels grades used in energetic applications. With this purpose samples were pre-charged with gaseous hydrogen at 19.5 MPa and 450 °C for 21 h. Then fracture tests of the pre-charged specimens were performed using different displacement rates. It is showed that the lower is the displacement rate and the largest is the steel strength the strongest is the reduction of the fracture toughness due to the presence of internal hydrogen.

Energy storage is a promising approach to address the challenge of intermittent generation from renewables on the electric grid. In this work we evaluate energy storage with a regenerative hydrogen fuel cell (RHFC) using net energy analysis. We examine the most widely installed RHFC configuration containing an alkaline water electrolyzer and a PEM fuel cell. To compare RHFC's to other storage technologies we use two energy return ratios: the electrical energy stored on invested (ESOI_e) ratio (the ratio of electrical energy returned by the device over its lifetime to the electrical-equivalent energy required to build the device) and the overall energy efficiency (the ratio of electrical energy returned by the device over its lifetime to total lifetime electrical-equivalent energy input into the system). In our reference scenario the RHFC system has an ESOI_eratio of 59 more favorable than the best battery technology available today (Li-ion ESOI_e= 35). (In the reference scenario RHFC the alkaline electrolyzer is 70% efficient and has a stack lifetime of 100 000 h; the PEM fuel cell is 47% efficient and has a stack lifetime of 10 000 h; and the round-trip efficiency is 30%.) The ESOIe ratio of storage in hydrogen exceeds that of batteries because of the low energy cost of the materials required to store compressed hydrogen and the high energy cost of the materials required to store electric charge in a battery. However the low round-trip efficiency of a RHFC energy storage system results in very high energy costs during operation and a much lower overall energy efficiency than lithium ion batteries (0.30 for RHFC vs. 0.83 for lithium ion batteries). RHFC's represent an attractive investment of manufacturing energy to provide storage. On the other hand their round-trip efficiency must improve dramatically before they can offer the same overall energy efficiency as batteries which have round-trip efficiencies of 75–90%. One application of energy storage that illustrates the trade-off between these different aspects of energy performance is capturing overgeneration (spilled power) for later use during times of peak output from renewables. We quantify the relative energetic benefit of adding different types of energy storage to a renewable generating facility using [EROI]grid. Even with 30% round-trip efficiency RHFC storage achieves the same [EROI]grid as batteries when storing overgeneration from wind turbines because its high ESOI_eratio and the high EROI of wind generation offset the low round-trip efficiency.

Press hardening steel (PHS) is widely applied in current automotive body design. The trend of using PHS grades with strengths above 1500 MPa raises concerns about sensitivity to hydrogen embrittlement. This study investigates the hydrogen delayed fracture sensitivity of steel alloy 32MnB5 with a 2000 MPa tensile strength and that of several alloy variants involving molybdenum and niobium. It is shown that the delayed cracking resistance can be largely enhanced by using a combination of these alloying elements. The observed improvement appears to mainly originate from the obstruction of hydrogen-induced damage incubation mechanisms by the solutes as well as the precipitates of these alloying elements.

The cost of the hydrogen value chain needs to be reduced to allow the widespread development of hydrogen applications. Mechanical compressors widely used for compressing hydrogen to date account for more than 50% of the CAPEX (capital expenditure) in a hydrogen refuelling station. Moreover mechanical compressors have several disadvantages such as the presence of many moving parts hydrogen embrittlement and high consumption of energy. Non-mechanical hydrogen compressors have proven to be a valid alternative to mechanical compressors. Among these electrochemical compressors allow isothermal and therefore highly efficient compression of hydrogen. On the other hand adsorption-desorption compressors allow hydrogen to be compressed through cooling/heating cycles using highly microporous materials as hydrogen adsorbents. A non-mechanical hybrid hydrogen compressor consisting of a first electrochemical stage followed by a second stage driven by adsorption-desorption of hydrogen on activated carbons allows hydrogen to be produced at 70 MPa a value currently required for the development of hydrogen automotive applications. This system has several advantages over mechanical compressors such as the absence of moving parts and high compactness. Its use in decentralized hydrogen facilities such as hydrogen refuelling stations can be considered

Integrated energy systems have become an area of interest as with growing energy demand globally means of producing sustainable energy from flexible sources is key to meet future energy demands while keeping carbon emissions low. Hydrogen is a potential solution for providing flexibility in the future energy mix as it does not emit harmful gases when used as an energy source. In this paper an integrated energy system including hydrogen as an energy vector and hydrogen storage is studied. The system is used to assess the behaviour of a hydrogen production and storage system under different renewable energy generation profiles. Two case studies are considered: a high renewable energy generation scenario and a low renewable energy generation scenario. These provide an understanding of how different levels of renewable penetration may affect the operation of an electrolyser and a fuel cell against an electricity import/export pricing regime. The mathematical model of the system under study is represented using the energy hub approach with system optimisation through linear programming conducted via MATLAB to minimise the total operational cost. The work undertaken showcases the unique interactions the fuel cell has with the hydrogen storage system in terms of minimising grid electricity import and exporting stored hydrogen as electricity back to the grid when export prices are competitive.

Overview of advances in the technology of solid state hydrogen storage methods applying different kinds of novel materials is provided. Metallic and intermetallic hydrides complex chemical hydride nanostructured carbon materials metal-doped carbon nanotubes metal-organic frameworks (MOFs) metal-doped metal organic frameworks covalent organic frameworks (COFs) and clathrates solid state hydrogen storage techniques are discussed. The studies on their hydrogen storage properties are in progress towards positive direction. Nevertheless it is believed that these novel materials will offer far-reaching solutions to the onboard hydrogen storage problems in near future. The review begins with the deficiencies of current energy economy and discusses the various aspects of implementation of hydrogen energy based economy.

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.

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.