Institution of Gas Engineers & Managers

There is significant interest in Australia both federally and at the state level to develop a hydrogen production industry. Australia’s Chief Scientist Alan Finkel recently prepared a briefing paper for the COAG Energy Council outlining a road map for hydrogen. It identifies hydrogen has the potential to be a significant source of export revenue for Australia in future years assist with decarbonising Australia’s economy and could establish Australia as a leader in low emission fuel production.

As part of the ongoing investigations into the hydrogen production potential of Australia Geoscience Australia has been commissioned by the Department of Industry Innovation and Science to develop heat maps that show areas with high potential for future hydrogen production. The study is technology agnostic in that it considers hydrogen production via electrolysis using renewable energy sources and also fossil fuel hydrogen coupled with carbon capture and storage (CCS). The heat maps presented in this work are synthesized from the key individual national-scale datasets that are relevant for hydrogen production. In the case of hydrogen from electrolysis renewable energy potential and the availability of water are the most important factors with various infrastructural considerations playing a secondary role. In the case of fossil fuel hydrogen proximity to gas and coal resources water and availability of carbon storage sites are the important parameters that control the heat maps. In this report we present 5 different heat map scenarios reflecting different assumptions in the geospatial analysis and also reflecting to some degree the different projected timeframes for hydrogen production. The first three scenarios pertain to renewable energy and hydrogen There is significant interest in Australia both federally and at the state level to develop a hydrogen production industry. In August 2018 Australia’s Chief Scientist Dr Alan Finkel prepared a briefing paper for the COAG Energy Council outlining a road map for hydrogen. It identifies hydrogen has the potential to be a significant source of export revenue for Australia in future years assist with decarbonising Australia’s economy and could establish Australia as a leader in low emission fuel production.

As part of ongoing investigations into the hydrogen production potential of Australia Geoscience Australia has been engaged by the Department of Industry Innovation and Science to develop maps that show areas with high potential for future hydrogen production. The study is technology agnostic but considers only low carbon production processes. It includes hydrogen production via electrolysis using renewable energy sources (referred to as renewable hydrogen) as well as fossil fuel-derived hydrogen coupled with carbon capture and storage (CCS) (referred to as CCS hydrogen). The maps presented in this work are synthesized from the key individual national-scale datasets that are relevant for hydrogen production. In the case of hydrogen from electrolysis renewable energy potential (from wind solar and hydro resources) and the availability of water are the most important factors while various infrastructure considerations also play a role. In the case of CCS hydrogen proximity to gas and coal resources water and availability of carbon storage sites are the important parameters that control the spatial distribution of potential hydrogen production. In this report we present five different scenarios that reflect key differences in technologies for hydrogen production and the requirements of those technologies. Using geospatial analysis each scenario is translated into a heat map that shows regional trends in potential for hydrogen production based on access to underpinning resources and existing infrastructure.

Three scenarios explore the future potential for renewable hydrogen produced by electrolysis. These demonstrate a high potential for hydrogen production in the future near many Australian coastal areas which is even larger if infrastructure is available to transport renewable power generated from inland areas to the coast. Results also show significant future potential for hydrogen production in inland areas where water is available. The final two scenarios focus on the future potential for CCS hydrogen: a 2030 scenario and a 2050 scenario. A key factor in future CCS hydrogen potential is related to the timeframes for the availability of geological storage resources for CO_2.

Biomass-based gasification is an attractive and promising pathway for hydrogen production. In this work a biomass-based hydrogen production system integrated with organic Rankine cycle was designed and investigated to predict the performance of hydrogen production yield and electricity generation under various operating conditions. The modified equilibrium model presented desirable results for the produced syngas compositions compared with the experimental data. Hydrogen yields from four types of biomass (wood chips daily manure sorghum and grapevine pruning wastes) were compared under the same operating condition with wood chips exhibiting the maximum hydrogen yield of 11.59 mol/kg. The effects of gasification temperature equivalence ratio and steam-to-biomass ratio on the hydrogen yield and electricity generation were investigated by using the response surface method. Furthermore the system was optimized using a genetic algorithm based on the response surface model. A preferred optimal solution with a hydrogen yield of 39.31 mol/kg and an output power of 3558.08 kW (0.99 kW h/kg) was selected by the linear programming technique for multidimensional analysis of the preference method.

In this paper a gas-to-power (GtoP) system for power outages is digitally modeled and experimentally developed. The design includes a solid-state hydrogen storage system composed of TiFeMn as a hydride forming alloy (6.7 kg of alloy in five tanks) and an air-cooled fuel cell (maximum power: 1.6 kW). The hydrogen storage system is charged under room temperature and 40 bar of hydrogen pressure reaching about 110 g of hydrogen capacity. In an emergency use case of the system hydrogen is supplied to the fuel cell and the waste heat coming from the exhaust air of the fuel cell is used for the endothermic dehydrogenation reaction of the metal hydride. This GtoP system demonstrates fast stable and reliable responses providing from 149 W to 596 W under different constant as well as dynamic conditions. A comprehensive and novel simulation approach based on a network model is also applied. The developed model is validated under static and dynamic power load scenarios demonstrating excellent agreement with the experimental results.

With the gradual popularization of hydrogen fuel cell vehicles (HFCVs) the construction and planning of hydrogen refueling stations (HRSs) are increasingly important. Taking operational HRSs in China’s coastal and major cities as examples we consider the main factors affecting the site selection of HRSs in China from the three aspects of economy technology and society to establish a site selection evaluation system for hydrogen refueling stations and determine the weight of each index through the analytic hierarchy process (AHP). Then combined with fuzzy comprehensive evaluation (FCE) method and artificial neural network model (ANN) FCE method is used to evaluate HRS in operation in China's coastal areas and major cities and we used the resulting data obtained from the comprehensive evaluation as the training data to train the neural network. So an intelligent site selection model for HRSs based on fuzzy comprehensive evaluation and artificial neural network model (FCE-ANN) is proposed. The planned HRSs in Shanghai are evaluated and an optimal site selection of the HRS is obtained. The results show that the optimal HRSs site selected by the FCE-ANN model is consistent with the site selection obtained by the FCE method and the accuracy of the FCE-ANN model is verified. The findings of this study may provide some guidelines for policy makers in planning the hydrogen refueling stations

In super duplex stainless steels (SDSSs) both austenite and ferrite are susceptible to hydrogen embrittlement however there is a lack of understanding into the effect of hydrogen in each phase. In this study in neutron diffraction was applied on hydrogen-charged (H-charged) samples to investigate the hydrogen embrittlement behaviour in super duplex stainless steels. The result reveals that austenite maintains good plasticity during tensile testing whilst a loss of it is realised in ferrite. Fractography analysis reveals the diffusion of hydrogen induced a brittle-to-ductile transition from the sample surface towards the centre; hydrogen embrittlement vanishes as the specimen’s centre is approached while it is demonstrated to disappear first in austenite but not in ferrite. This transition can be predicted by applying a physics-based hydrogen embrittlement model which incorporates the effects of hydrogen concentration hydrogen diffusivity residual stress loading state and temperature. The present work demonstrates the dissimilar susceptibility of austenite and ferrite to hydrogen embrittlement providing a tool to describe it.

With the rapid development of hydrogen vehicle technology and large scale fuel cell vehicle (FCV) demonstration project worldwide more hydrogen refueling stations need to be built. Safety distances of hydrogen refueling stations have always been a public concern and have become a critical issue to further implementation of hydrogen station. In this paper safety distances for 35MPa and 70MPa gaseous hydrogen refueling station are evaluated on the basis of the maximum consequences likely to occur. Four typical consequences of hydrogen release are considered in modeling: physical explosion jet fire flash fire and confined vapor cloud explosion. Results show that physical explosion and the worst case of confined vapor cloud explosion produce the longest harm effect distances for instantaneous and continuous release respectively indicating that they may be considered as leading consequences for the determination of safety distances. For both 35MPa station and 70MPa station safety measures must be implemented because the calculated safety distances of most hydrogen facilities can not meet the criteria in national code if without sufficient mitigation measures. In order to reduce the safety distances to meet the national code some mitigation measures are investigated including elevation of hydrogen facilities using smaller vessel and pipe work and setting enclosure around compressors. Results show that these measures are effective to improve safety but each has different effectiveness on safety distance reduction. The combination of these safety measures may effectively eliminate the hazard of 35MPa station however may be not enough for 70MPa station. Further improvements need to be studied for compressors inside 70MPa station.

Liquid hydrogen vent stacks often release hydrogen for example due to pressure relief from an underutilized tank boiling off hydrogen or after hydrogen delivery and transfer (trucks often depressurize through the tank vent stack to meet pressure regulations for on-road transport).<br/>A rapid release of cryogenic hydrogen through a vent stack will condense moisture from the entrained air forming a visible cloud. It is often assumed that the extent of the cold hydrogen is concurrent with the cloud. In this work a laser-based Raman scattering diagnostic was used to map out the hydrogen location during a series of vent stack release experiments. A description of the diagnostic instrument is given followed by a comparison of hydrogen signals to the visible cloud for releases through a liquid hydrogen vent stack. A liquid hydrogen pump was used to vary the flowrate of hydrogen through the vent stack and tests were performed under low and high wind conditions as well as low and high humidity conditions. The hydrogen was observed only where the condensed moisture was located regardless of the humidity level or wind. These measurements are being used to validate models such as those included in Sanda’s HyRAM toolkit and inform safety codes and standards.

Exposing and stabilizing undercoordinated platinum (Pt) sites and therefore optimizing their adsorption to reactive intermediates offers a desirable strategy to develop highly efficient Pt-based electrocatalysts. However preparation of atomically controllable Pt-based model catalysts to understand the correlation between electronic structure adsorption energy and catalytic properties of atomic Pt sites is still challenging. Herein we report the atomically thin two-dimensional PtTe₂ nanosheets with well-dispersed single atomic Te vacancies (Te-SAVs) and atomically well-defined undercoordinated Pt sites as a model electrocatalyst. A controlled thermal treatment drives the migration of the Te-SAVs to form thermodynamically stabilized ordered Te-SAV clusters which decreases both the density of states of undercoordinated Pt sites around the Fermi level and the interacting orbital volume of Pt sites. As a result the binding strength of atomically defined Pt active sites to H intermediates is effectively reduced which renders PtTe₂ nanosheets highly active and stable in hydrogen evolution reaction.

Blending hydrogen (H2) produced from PEM electrolysis coupled to Renewable Energy Sources (RES) in the existing Natural Gas (NG) network is a promising option for the deep decarbonization of the gas sector. However blending H2 with NG significantly affects the thermophysical properties of the gas mixture changing the gas supply requirements to meet the demand. In this work different scenarios of green hydrogen blending (Blend Ratio BR equal to 5/10/15/20%vol) are analyzed at the national level with different temporal constraints (hour/day/week/month/year) based on real gas demand data in Italy addressing both design requirements (RES and PEM electrolyzer capacity) via Linear Programming (LP) and carrying out dynamic simulations of different operational strategies (constant or variable blend). Although H2/NG blending provides a huge opportunity in terms of deployed H2 volume higher BRs show rapidly increasing design requirements (1.3-1.5 GWe/%vol and 2.5-3 GWe/%vol for PEM electrolyzers and RES capacity respectively) and a significative increase of the total gas mixture volume (0.83 %/%vol) which hinders the CO2 reduction potential (0.37 %/%vol). A variable blend operation strategy (allowing a variation of BR within the analyzed period) allows to balance a variable H2 production from RES. Wider temporal constraints imply several beneficial effects such as relaxing design constraints and avoiding the implementation of an external storage. The Levelized Cost Of Hydrogen (LCOH) is preliminarily estimated at around 7.3 $/kg for yearly scenarios (best-case) although shorter temporal constraints entail significant excess hydrogen which would increase the LCOH if not deployed for other applications.

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.