Publications

The safest way to store hydrogen is in solid form physically entrapped in molecular form in highly porous materials or chemically bound in atomic form in hydrides. Among the different families of these compounds alkaline and alkaline earth metals alumino-hydrides (alanates) have been regarded as promising storing media and have been extensively studied since 1997 when Bogdanovic and Schwickardi reported that Ti-doped sodium alanate could be reversibly dehydrogenated under moderate conditions. In this review the preparative methods; the crystal structure; the physico-chemical and hydrogen absorption-desorption properties of the alanates of Li Na K Ca Mg Y Eu and Sr; and of some of the most interesting multi-cation alanates will be summarized and discussed. The most promising alanate-based reactive hydride composite (RHC) systems developed in the last few years will also be described and commented on concerning their hydrogen absorption and desorption performance.

Hydrogen energy vehicles are being increasingly widely used. To ensure the safety of hydrogenation stations research into the detection of hydrogen leaks is required. Offline analysis using data machine learning is achieved using Spark SQL and Spark MLlib technology. In this study to determine the safety status of a hydrogen refueling station we used multiple algorithm models to perform calculation and analysis: a multi-source data association prediction algorithm a random gradient descent algorithm a deep neural network optimization algorithm and other algorithm models. We successfully analyzed the data including the potential relationships internal relationships and operation laws between the data to detect the safety statuses of hydrogen refueling stations.

This study evaluates the environmental profile of a real biomass-based hydrogen production small-scale (1 MWth) system composed of catalytic candle indirectly heated steam gasifier coupled with zinc oxide (ZnO) guard bed water gas shift (WGS) and pressure swing absorber (PSA) reactors. Environmental performance from cradle-to-gate was investigated by life cycle assessment (LCA) methodology. Biomass production shows high influence over all impact categories. In the syngas production process the main impacts observed are global warming potential (GWP) and acidification potential (AP). Flue gas emission from gasifier burner has the largest proportion of total GWP. The residual off gas use in internal combustion engine (ICE) leads to important environmental savings for all categories. Hydrogen renewability score is computed as 90% due to over 100% decline in non-renewable energy demand. Sensitivity analysis shows that increase in hydrogen production efficiency does not necessarily result in decrease in environmental impacts. In addition economic allocation of environmental charges increases all impact categories especially AP and photochemical oxidation (POFP).

Because of the emergence of the U.E. “green deal” and because of the significant implication of national and regional authorities throughout Europe the “hydrogen” economy is emerging. And with it numerous questions and experimentations. One of them perhaps a key point is the storage and transport of hydrogen. Liquid hydrogen in cryogenic conditions is a possibility already used in the space industry but under a lot of constrains. What may be acceptable in a well-controlled and restrained domain may not be realistic in a wider application closer to the public. Safety should be ensured and there is a need for a better knowledge of the flammable and ignition properties of the “cold” hydrogen mixtures following a cryogenic spillage for instance to select adequate ATEX equipment. The purpose of PRESLHY project [4] is to investigate the ignition fire and explosion characteristics of cryogenic hydrogen spillages and to propose safety engineering methods. The present work is part of it and addresses the measurement of the laminar burning velocity (Sl) flammability limits (FL) minimum ignition energy (MIE)… of hydrogen air mixtures at atmospheric pressure but down to -150°C. To do this a special burner was designed with details given inside this paper together with the experimental results. It is found that the FL domain is reduced when the temperature drops that MIE increases slightly and Sl decreases.

It is well known that ferrous materials can be damaged by absorption of hydrogen. If a sufficient quantity of hydrogen penetrates into the material static fracture and the material's fatigue performances can be affected negatively in particular causing an increase in the material crack growth rates. The latter is often referred as Hydrogen Affected-Fatigue Crack Growth Rate (HA-FCGR). It is therefore of paramount importance to quantify the impact in terms of hydrogen induce fatigue crack growth acceleration in order to determine the life of components exposed to hydrogen and avoid unexpected catastrophic failures. In this study in-situ fatigue crack growth rate testing on Compact Tension (CT) specimens were carried out to determine the fatigue crack growth behaviour for a Fe-3 wt%Si alloy and X70 pipeline steel. Tests were carried out in two environmental conditions i.e. laboratory air and in-situ electrochemically charged hydrogen and different mechanical conditions in terms of load ratio (R = 0.1 and R = 0.5 for the Fe-3 wt%Si R = 0.1 for the X70 steel) and test frequency (f = 0.1 Hz 1 Hz and 10 Hz) were adopted under electrochemically charged hydrogen conditions. The results show a clear detrimental effect of H for the specimens tested in hydrogen when compared to the specimens tested in air for both materials and that the impact of hydrogen is test frequency-dependent: the hydrogen induced acceleration is more prominent as the frequency is decreased. Post-mortem surface investigations consistently relate the global crack growth acceleration to a shift from transgranular to Quasi-cleavage fracture mechanism. Despite such consistency the acceleration factor strongly depends on the material: Fe-3wt%Si features acceleration up to 1000 times while X70 accelerates up to 76 times when compare to the material fatigue crack growth rate recorded in air. Observation of the deformation activities in the crack wake in relation to the transition into hydrogen accelerated regime in fatigue crack growth show a tendency toward restricted plastic activity in presence of hydrogen.

The National Hydrogen Roadmap provides a blueprint for the development of a hydrogen industry in Australia.

Recently there has been a considerable amount of work undertaken (both globally and domestically) seeking to quantify the economic opportunities associated with hydrogen. The National Hydrogen Roadmap takes that analysis a step further by focusing on how those opportunities can be realised.

National Hydrogen Roadmap

The National Hydrogen Roadmap provides a blueprint for the development of a hydrogen industry in Australia.

The primary objective of the Roadmap is to provide a blueprint for the development of a hydrogen industry in Australia. With a number of activities already underway it is designed to help inform the next series of investment amongst various stakeholder groups (e.g. industry government and research) so that the industry can continue to scale in a coordinated manner.

Pathways to an economically sustainable industry

The low emissions hydrogen value chain now consists of a series of mature technologies. While there is considerable scope for further R&D this level of maturity has meant that the narrative has shifted from one of technology development to market activation.

Barriers to market activation stem from a lack of supporting infrastructure and/or the cost of hydrogen supply. However both barriers can be overcome via a series of strategic investments along the value chain from both the private and public sector.

The report shows that while government assistance is needed to kick-start the industry it can become economically sustainable thereafter. This is demonstrated by first assessing the target price of hydrogen needed for it be competitive with other energy carriers and feedstocks. Second the assessment considers the current state of the industry namely the cost and maturity of the underpinning technologies and infrastructure. It then identifies the material cost drivers and consequently the key priorities and areas for investment needed to make hydrogen competitive in each of the identified markets.

The opportunity for hydrogen to compete favourably on a cost basis in local applications such as transport and remote area power systems is within reach based on potential cost reductions to 2025. Further the development of a hydrogen export industry represents a significant opportunity for Australia and a potential 'game changer' for the local industry and the broader energy sector due to associated increases in scale."

You can read the full report on the CSIRO website at this link

Fatigue crack growth (FCG) tests for compact tension (CT) specimens of an annealed low-carbon steel JIS-SM490B were performed under various combinations of hydrogen pressures ranging from 0.1 to 90 MPa test frequencies from 0.001 to 10 Hz and test temperatures of room temperature (RT) 363 K and 423 K. In the hydrogen pressures of 0.1 0.7 and 10 MPa at RT the FCG rate increased with a decrease in the test frequency; then peaked out. In the lower test frequency regime the FCG rate decreased and became nearly equivalent to the FCG rate in air. Also in hydrogen pressure of 45 MPa at RT the hydrogen-assisted FCG acceleration showed an upper limit around the test frequencies of 0.01 to 0.001 Hz. On the other hand in the hydrogen pressure of 90 MPa at RT the FCG rate monotonically increased with a decrease in the test frequency and eventually the upper limit of FCG acceleration was not confirmed down to the test frequency of 0.001 Hz. In the hydrogen pressure of 0.7 MPa at the test frequency of 1 Hz and temperatures of 363 K and 423 K the stress intensity factor range ΔK for the onset of the FCG acceleration in hydrogen gas was shifted to a higher ΔK with an increase in the test temperature. The laser-microscope observation at specimen surface revealed that the hydrogen-assisted FCG acceleration always accompanied a localization of plastic deformation near crack tip. These results infer that the influencing factor dominating the hydrogen-assisted FCG acceleration is not the presence or absence of hydrogen in material but is how hydrogen localizes near the crack tip. Namely a steep gradient of hydrogen concentration can result in the slip localization at crack tip which enhances the Hydrogen Enhanced Successive Fatigue Crack Growth (HESFCG) proposed by the authors. It is proposed that such a peculiar dependence of FCG rate on hydrogen pressure test frequency and test temperature can be unified by using a novel parameter representing the gradient of hydrogen concentration near crack tip.

Structural integrity of reactor pressure vessel (RPV) in light water reactors (LWR) is of highest importance regarding operation safety and lifetime. The fracture behaviour of low-alloy RPV steels with different dynamic strain aging (DSA) & environmental assisted cracking (EAC) susceptibilities in simulated LWR environments was evaluated by elastic plastic fracture mechanics tests (EPFM) and by metallo- and fractographic post-test analysis. Exposure to high temperature water (HTW) environments at LWR temperatures revealed only moderated reductions in the fracture initiation and tearing resistance of low alloy RPV steels with high DSA or EAC susceptibility accompanied with a moderate but clear change in fracture morphology which indicates the potential synergies of hydrogen/HTW embrittlement with DSA and EAC under suitable conditions. The most pronounced degradation effects occurred in a) RPV steels with high DSA susceptibility where the fracture initiation and tearing resistance reduction increased with decreasing loading rate and were most pronounced in hydrogenated HTW and b) high sulphur steels with high EAC susceptibility in aggressive occluded crevice environment and with preceding fast EAC crack growth in oxygenated HTW. The moderate effects are due to the low hydrogen availability in HTW together with high density of fine-dispersed hydrogen traps in RPV steels. Stable ductile transgranular tearing by microvoid coalescence was the dominant failure mechanism in all environments with additional varying few % of secondary cracks macrovoids and quasi-cleavage in HTW. The observed behavior suggests a combination of plastic strain localisation by the Hydrogen-enhanced Local Plasticity (HELP) mechanism in synergy with DSA and Hydrogen-enhanced Strain-induced Vacancies (HESIV) mechanism with additional minor contributions of Hydrogen-enhanced Decohesion Embrittlement (HEDE) mechanism.

Hydrogen Embrittlement (HE) leads to deterioration of the fracto-mechanical properties of metals. In spite of vast literature it is still not clearly understood and demands significant research on this topic. For better understanding of the hydrogen effect on fatigue behaviour of metals present work focuses on developing a computational framework for fatigue crack initiation studies in metals in the presence of hydrogen. The developed framework consists of a nonlocal crystal plasticity model coupled with hydrogen transport model to study the fatigue behaviour of hydrogen charged metals. The nonlocal crystal plasticity model accounts for the statistically stored dislocations (SSDs) and geometrically necessary dislocations (GNDs) in polycrytalline metal. Hydrogen transport model on the other hand accounts for diffusion and trapping behavior of hydrogen due to concentration gradient pressure gradient plastic strain-rate with dislocations as the only trapping sites along the slip systems. A polycrystalline representative volume element (RVE) with periodic boundary conditions is used in this study. Fatigue crack initiation criterion is proposed for the simulated RVE with controlled microstructure by considering a critical value of the fatigue indicator parameter (FIP). FIP is formulated based on the experimental observations of several crack initiation sites along the grain boundaries their normal direction with respect to loading direction and the accumulated plastic strain in nickel polycrystalline samples. Developed simulation framework correctly accounts cyclic stress-strain behavior and multiple fatigue crack initiation sites observed experimentally in the presence of hydrogen.

Hydrogen (H) presence in metals is detrimental as unpredictable failure might occur. Recent developments in material’s design indicated that microstructural features such as precipitates play an essential role in potentially increasing the resistance against H induced failure. This work evaluates the H trapping characteristics for TiC and V₄C₃ by thermal desorption spectroscopy and permeation experiments. Two microstructural conditions are compared: as quenched vs. quenched and tempered in which the carbides are introduced. The tempered induced precipitates are able to deeply trap a significant amount of H which decreases the H diffusivity in the materials and removes some of the detrimental H from the microstructure. For microstructural design purposes it is important to know the position of H. Here H is demonstrated to be trapped at the carbide/matrix interface by modifying the tempering treatment.