Japan

Hydrogen energy utilization is expected due to its environmental and energy efficiencies. However many issues remain to be solved in the social implementation of hydrogen energy through water electrolysis. This analyzes and compares the energy consumption and GHG emissions of fossil fuel-derived hydrogen and gasoline energy systems over their entire life cycle. The results demonstrate that for similar vehicle weights the hydrogen energy system consumes 1.8 MJ/km less energy and emits 0.15 kg-CO 2 eq./km fewer GHG emissions than those of the gasoline energy system. Hydrogen derived from fossil fuels may contribute to future energy systems due to its stable energy supply and economic efficiency. Lowering the power source carbon content also improved the environmental and energy efficiencies of hydrogen energy derived from fossil fuels.

Detailed analysis of pathways to future sustainable energy systems is important in order to identify and overcome potential constraints and negative impacts and to increase the utility and speed of this transition. A key aspect of a shift to renewable energy technologies is their relatively higher metal intensities. In this study a bottom-up cost-minimizing energy model is used to calculate aggregate metal requirements in different energy technology including hydrogen and climate policy scenarios and under a range of assumptions reflecting uncertainty in future metal intensities recycling rate and life time of energy technologies. Metal requirements are then compared to current production rates and resource estimates to identify potentially “critical” metals. Three technology pathways are investigated: 100 percent renewables coal & nuclear and gas & renewables each under the two different climate policies: net zero emissions satisfying the well-below 2 °C target and business as usual without carbon constraints resulting together in six scenarios. The results suggest that the three different technology pathways lead to an almost identical degree of warming without any climate policy while emissions peaks within a few decades with a 2 °C policy. The amount of metals required varies significantly in the different scenarios and under the various uncertainty assumptions. However some can be deemed “critical” in all outcomes including Vanadium. The originality of this study lies in the specific findings and in the employment of an energy model for the energy-mineral nexus study to provide better understanding for decision making and policy development.

Comprehensive risk assessment across multiple fields is required to assess the potential utility of hydrogen energy technology. In this research we analyzed environmental and socio-economic effects during the entire life cycle of a hydrogen energy system using input-output tables. The target system included hydrogen production by naphtha reforming transportation to hydrogen stations and FCV (Fuel Cell Vehicle) refilling. The results indicated that 31% 44% and 9% of the production employment and greenhouse gas (GHG) emission effects respectively during the manufacturing and construction stages were temporary. During the continuous operation and maintenance stages these values were found to be 69% 56% and 91% respectively. The effect of naphtha reforming was dominant in GHG emissions and the effect of electrical power input on the entire system was significant. Production and employment had notable effects in both the direct and indirect sectors including manufacturing (pumps compressors and chemical machinery) and services (equipment maintenance and trade). This study used data to introduce a life cycle perspective to environmental and socio-economic analysis of hydrogen energy systems and the results will contribute to their comprehensive risk assessment in the future.

The dynamics of hydrogen in metals with mixed grain structure is not well understood at a microscopic scale. One of the biggest issues facing the hydrogen economy is “hydrogen embrittlement” of metal induced by hydrogen entering and diffusing into the material. Hydrogen diffusion in metallic materials is difficult to grasp owing to the non-uniform compositions and structures of metal. Here a time-resolved “operando hydrogen microscope” was used to interpret local diffusion behaviour of hydrogen in the microstructure of a stainless steel with austenite and martensite structures. The martensite/austenite ratios differed in each local region of the sample. The path of hydrogen permeation was inferred from the time evolution of hydrogen permeation in several regions. We proposed a model of hydrogen diffusion in a dual-structure material and verified the validity of the model by simulations that took into account the transfer of hydrogen at the interfaces.

Hydrogen and its energy carriers such as liquid hydrogen (LH2) methylcyclohexane (MCH) and ammonia (NH3) are essential components of low-carbon energy systems. To utilize hydrogen energy the complete environmental merits of its supply chain should be evaluated. To understand the expected environmental benefit under the uncertainty of hydrogen technology development we conducted life-cycle inventory analysis and calculated CO2 emissions and their uncertainties attributed to the entire supply chain of hydrogen and NH3 power generation (co-firing and mono-firing) in Japan. Hydrogen was assumed to be produced from overseas renewable energy sources with LH2/MCH as the carrier and NH3 from natural gas or renewable energy sources. The Japanese life-cycle inventory database was used to calculate emissions. Monte Carlo simulations were performed to evaluate emission uncertainty and mitigation factors using hydrogen energy. For LH2 CO2 emission uncertainty during hydrogen liquefaction can be reduced by using low-carbon fuel. For MCH CO2 emissions were not significantly affected by power consumption of overseas processes; however it can be reduced by implementing low-carbon fuel and waste-heat utilization during MCH dehydrogenation. Low-carbon NH3 production processes significantly affected power generation whereas carbon capture and storage during NH3 production showed the greatest reduction in CO2 emission. In conclusion reducing CO2 emissions during the production of hydrogen and NH3 is key to realize low-carbon hydrogen energy systems.

Global climate change concerns have pushed international governmental actions to reduce greenhouse gas emissions by adopting cleaner technologies hoping to transition to a more sustainable society. The hydrogen economy is one potential long-term option for enabling deep decarbonization for the future energy landscape. Progress towards an operating hydrogen economy is discouragingly slow despite global efforts to accelerate it. There are major mismatches between the present situation surrounding the hydrogen economy and previous proposed milestones that are far from being reached. The overall aim of this study is to understand whether there has been significant real progress in the achievement of a hydrogen economy or whether the current interest is overly exaggerated (hype). This study uses bibliometric analysis and content analysis to historically map the hydrogen economy’s development from 1972 to 2020 by quantifying and analyzing three sets of interconnected data. Findings indicate that interest in the hydrogen economy has significantly progressed over the past five decades based on the growing numbers of academic publications media coverage and projects. However various endogenous and exogenous factors have influenced the development of the hydrogen economy and created hype at different points in time. The consolidated results explore the changing trends and how specific events or actors have influenced the development of the hydrogen economy with their agendas the emergence of hype cycles and the expectations of a future hydrogen economy.

Biomaterials attract a lot of attention as next-generation materials. Especially in the energy field fuel cells based on biomaterials can further develop clean next-generation energy and are focused on with great interest. In this study solid-state hydrogen fuel (PSII–chitin composite) composed of the photosystem II (PSII) and hydrated chitin composite was successfully created. Moreover a biofuel cell consisting of the electrolyte of chitin and the hydrogen fuel using the PSII– chitin composite was fabricated and its characteristic feature was investigated. We found that proton conductivity in the PSII–chitin composite increases by light irradiation. This result indicates that protons generate in the PSII–chitin composite by light irradiation. It was also found that the biofuel cell using the PSII–chitin composite hydrogen fuel and the chitin electrolyte exhibits the maximum power density of 0.19 mW/cm2 . In addition this biofuel cell can drive an LED lamp. These results indicate that the solid-state biofuel cell based on the bioelectrolyte “chitin” and biofuel “the PSII–chitin composite” can be realized. This novel solid-state fuel cell will be helpful to the fabrication of next-generation energy.

Realizing the hydrogen economy in Japan entails a risk assessment of its domestic hydrogen supply especially hydrogen transport by road. The first step of the risk assessment is to characterize the hydrogen transport accidents from different energy carriers. However it is difficult to characterize the accidents because hydrogen transport systems have not been fully implemented in Japan. The aim of this study is to characterize the hydrogen transport accidents from different energy carriers in Japan. We studied three major energy carriers namely compressed hydrogen liquefied hydrogen and liquid organic hydride. The accident networks based on network theory were constructed to capture the comprehensive accident processes and quantitatively characterized the hydrogen transport accidents from different energy carriers. The results clarified the differences and similarities in the accident process amongst the energy carriers. Furthermore key accident events were identified. This study contributes to the development of comprehensive hydrogen transport accident scenarios for risk assessment.

This paper addresses from both macro- and micro- areal coverage in introducing hydrogen system in terms of cost and performance where the produced hydrogen from surplus photovoltaic (PV) power is stored. Feed-in tariff in Japan had successful achievement for great expansion of renewable energy systems (RES) causing problematic operation due to excess power by overcapacity of RES. One of the candidate approaches to overcome this surplus energy by RES is Power to gas (P2G) system using electrolysis cells (ECs) fuel cells (FCs) or co-firing in gas turbines both for energy conversion as well as power balancing. Numerous studies had been investigated on P2G however within our knowledge no study had been addressed the system from both coverages with different capacity and scales. We investigate micro level (zero emission building in our university) and macro level (Kyushu one of big regions in Japan). We describe for macro side preliminary result on economic analysis of using surplus power of RES via production and storage of hydrogen while for micro side research design.

Ductile cast iron (DCI) is one of prospective materials used for the hydrogen equipment because of low-cost good workability and formability. The wide range of mechanical properties of DCI is obtained by controlling microstructural factors such as graphite size volume fraction of graphite matrix structure and so on. Therefore it is important to find out an optimal microstructural condition that is less susceptible to hydrogen embrittlement. In this study the effects of graphite size on the hydrogen absorption capability and the hydrogen-induced ductility loss of ferritic DCI were investigated.<br/>Several kinds of ferritic DCIs with a different graphite diameter of about 10 µm - 30 µm were used for the tensile test and the hydrogen content measurement. Hydrogen charging was performed prior to the tensile test by exposing a specimen to high-pressure hydrogen gas. Then the tensile test was performed in air at room temperature. The hydrogen content of a specimen was measured by a thermal desorption analyzer.<br/>It was found that the amount of hydrogen stored in DCI was dependent on the graphite size. As the graphite diameter increased the hydrogen content sharply increased at a certain graphite diameter and then it became nearly constant irrespective of increase in graphite diameter. In other words there was the critical graphite diameter that significantly changed the hydrogen absorption capability. The ductility was decreased by hydrogen and the hydrogen-induced ductility loss was dependent on the hydrogen content. Therefore the hydrogen embrittlement of DCI became remarkable when the graphite size was larger than the critical value.

Marked degradation of tensile properties induced by plastic deformation after dynamic interactions between strain-induced martensite transformation and hydrogen has been investigated for type 316L stainless steel by hydrogen thermal desorption analysis. Upon modified hydrogen charging reported previously the amount of hydrogen desorbed in the low temperature range increases; the degradation of tensile properties induced by interactions between plastic deformation and hydrogen at 25 °C or induced by interactions between martensite transformation and hydrogen at −196 °C occurs even for the stainless steel with high resistance to hydrogen embrittlement. The hydrogen thermal desorption behavior is changed by each interaction suggesting changes in hydrogen states. For specimen fractured at 25 °C the facet-like morphology and transgranular fracture are observed on the outer part of the fracture surface. At −196 °C a quasi-cleave fracture is observed at the initiation area. Modified hydrogen charging significantly interacts both plastic deformation and martensite transformation eventually enhancing the degradation of tensile properties. Upon plastic deformation at 25° C after the interactions between martensite transformation and hydrogen by straining to 0.2 at −196 °C cracks nucleate in association with martensite formed by the interactions at −196 °C and marked degradation of tensile properties occurs. It is likely that the interactions between martensite transformation and hydrogen induce damage directly related to the degradation thereby affecting subsequent deformation. Upon dehydrogenation after the interactions between the martensite transformation and hydrogen no degradation of tensile properties is observed. The damage induced by the interactions between martensite transformation and hydrogen probably changes to harmless defects during dehydrogenation.

Among several candidates of hydrogen storage liquid hydrogen methylcyclohexane (MCH) and ammonia are considered as potential hydrogen carriers in terms of their characteristics application feasibility and economic performance. In addition as a main motor in the hydrogen introduction Japan has focused and summarized the storage methods for hydrogen into these three methods. Each of them has advantages and disadvantages compared to each other. This study focuses on the effort to analyze and clarify the potential of these three hydrogen storages especially in terms of physical characteristics energy efficiency and economic cost. Liquid hydrogen faces challenges in huge energy consumption during liquefaction and boil-off during storage. MCH has main obstacles in largely required energy in dehydrogenation. Lastly ammonia encounters high energy demand in both synthesis and decomposition (if required). In terms of energy efficiency ammonia is predicted to have the highest total energy efficiency (34–37%) followed by liquid hydrogen (30–33%) and MCH (about 25%). In addition from cost calculation ammonia with direct utilization (without decomposition) is considered to have the highest feasibility for being massively adopted as it shows the lowest cost (20–22 JPY/Nm3-H2 in 2050). However in case that highly pure hydrogen (such as for fuel cell) is demanded liquid hydrogen looks to be promising (24–25 JPY/Nm3-H2 in 2050) compared to MCH and ammonia with decomposition and purification.

We at Kawasaki have proposed a “CO2 free H2 chain” using the abundant brown coal of Australia as a hydrogen source. We developed the basic design package and finished the Front End Engineering Design (FEED) in 2014. There are not only the hazards of the processing plant system but also the characteristic hazards of a hydrogen plant system. We considered and carried out Hazard Identification (HAZID) as the most appropriate approach for safety design in this stage. This paper describes the safety design and HAZID which we practiced for the CO2-Free Hydrogen Supply Chain FEED.

Renewable energy is free abundant clean and could contribute towards a significant reduction of the global warming emissions. It is massively introduced as a source of electricity production across the globe and is expected to become the primary source of energy within the following decades. However despite the naturally replenished energy the supply is not always available. For this reason it is necessary at times of excess energy any surplus quantity to be sufficiently captured stored and later used when a deficit occurs. In this paper an overview of a backup power system operating with a hydrogen-biodiesel dual-fuel internal combustion engine is provided. The system is utilizing the organic chemical hydride method for safe hydrogen storage and transportation. The high energy content of hydrogen stored in the form of an organic hydride under ambient conditions makes it an ideal energy backup medium for large-scale and long-term applications. The research work focusses on the operation and emissions output of the dual-fuel internal combustion engine running on fully renewable fuels and the results are compared with the conventional petroleum-derived diesel engine. Biodiesel-hydrogen operation shows significant benefits in the reduction of carbon and soot emissions but deteriorates the NOx formation compared to the conventional diesel-powered engines. The operation of the engine at high loads can provide high exhaust thermal energy while alternative combustion strategies are necessary to be implemented at low load conditions for the optimum operation of the backup power system.

Interest in reducing the greenhouse gas emissions from conventional power generation has increased the focus on the potential use of hydrogen to produce electricity. Numerous life-cycle assessment (LCA) studies of hydrogen-based power generation have been published. This study reviews the technological and methodological choices made in hydrogen-based power generation LCAs. A systematic review was chosen as the research method to achieve a comprehensive and minimally biased overview of hydrogen-based power generation LCAs. Relevant articles published between 2004 and 2021 were identified by searching the Scopus and Web of Science databases. Electrolysis from renewable energy resources was the most widely considered type of hydrogen production in the LCAs analyzed. Fuel cell technology was the most common conversion equipment used in hydrogen-based electricity LCAs. A significant number of scenarios examine the use of hydrogen for energy storage and co-generation purposes. Based on qualitative analysis the methodological choices of LCAs vary between studies in terms of the functional units allocations system boundaries and life-cycle impact assessment methods chosen. These discrepancies were likely to influence the value of the environmental impact results. The findings of the reviewed LCAs could provide an environmental profile of hydrogen-based electricity systems identify hotspots drive future research define performance goals and establish a baseline for their large-scale deployment.

Polymer electrolyte membrane (PEM) fuel cells are electrochemical devices that directly convert the chemical energy stored in fuel into electrical energy with a practical conversion efficiency as high as 65%. In the past years significant progress has been made in PEM fuel cell commercialization. By 2019 there were over 19000 fuel cell electric vehicles (FCEV) and 340 hydrogen refueling stations (HRF) in the U.S. (~8000 and 44 respectively) Japan (~3600 and 112 respectively) South Korea (~5000 and 34 respectively) Europe (~2500 and 140 respectively) and China (~110 and 12 respectively). Japan South Korea and China plan to build approximately 3000 HRF stations by 2030. In 2019 Hyundai Nexo and Toyota Mirai accounted for approximately 63% and 32% of the total sales with a driving range of 380 and 312 miles and a mile per gallon (MPGe) of 65 and 67 respectively. Fundamentals of PEM fuel cells play a crucial role in the technological advancement to improve fuel cell performance/durability and reduce cost. Several key aspects for fuel cell design operational control and material development such as durability electrocatalyst materials water and thermal management dynamic operation and cold start are briefly explained in this work. Machine learning and artificial intelligence (AI) have received increasing attention in material/energy development. This review also discusses their applications and potential in the development of fundamental knowledge and correlations material selection and improvement cell design and optimization system control power management and monitoring of operation health for PEM fuel cells along with main physics in PEM fuel cells for physics-informed machine learning. The objective of this review is three fold: (1) to present the most recent status of PEM fuel cell applications in the portable stationary and transportation sectors; (2) to describe the important fundamentals for the further advancement of fuel cell technology in terms of design and control optimization cost reduction and durability improvement; and (3) to explain machine learning physics-informed deep learning and AI methods and describe their significant potentials in PEM fuel cell research and development (R&D).

Hydrogen fuel in internal combustion engine gives a very big advantage to the transportation sector especially in solving the greenhouse emission problem. However there are only few research discovered the ability of argon as a working gas in hydrogen combustion in internal combustion engine. The high temperature rises from the argon compression tend to result in heat loss problem. This research aims to study the heat loss mechanism on wall surface condition in the combustion chamber. Experiments were conducted to study the effects of different heat flux sensor locations and the effect of ignition delay on heat flux. Local heat flux measurement was collected and images were observed using high speed shadowgraph images. The ignition delay that occurred near the combustion wall will result in larger heat loss throughout the combustion process. Higher ambient pressure results in a bigger amount of heat flux value. Other fundamental characteristics were obtained and discussed which may help in contributing the local heat loss data of an argon-circulated hydrogen engine in future engine operation.

Current safety codes and technical standards related to Japanese hydrogen refueling stations (HRSs) have been established based on qualitative risk assessment and quantitative effectiveness validation of safety measures for more than ten years. In the last decade there has been significant development in the technologies and significant increment in operational experience related to HRSs. We performed a quantitative risk assessment (QRA) of the HRS model representing Japanese HRSs with the latest information in the previous study. The QRA results were obtained by summing risk contours derived from each process unit. They showed that the risk contours of 10-3 and 10-4 per year were confined within the HRS boundaries whereas those of 10-5 and 10-6 per year are still present outside the HRS boundaries. Therefore we analyzed the summation of risk contours derived from each unit and identified the largest risk scenarios outside the station. The HRS model in the previous study did not consider fire and blast protection walls which could reduce the risks outside the station. Therefore we conducted a detailed risk analysis of the identified scenarios using 3D structure modeling. The heat radiation and temperature rise of jet fire scenarios that pose the greatest risk to the physical surroundings in the HRS model were estimated in detail based on computational fluid dynamics with 3D structures including fire protection walls. Results show that the risks spreading outside the north- west- and east-side station boundaries are expected to be acceptable by incorporating the fire protection wall into the Japanese HRS model.

We had investigated feasible measures to reduce CO2 emission and came to conclusion that introduction of new fuel such as hydrogen with near zero CO2 emission is required for achieving Japan’s commitment of 80% CO2 reduction by 2050. Under this background we are proposing and aiming to realize “CO2 free hydrogen chain” utilizing Australian brown coal linked with CCS. In this chain hydrogen produced from brown coal is liquefied and transported to Japan by liquid hydrogen carrier. We have conducted feasibility study of commercial scale “CO2 free hydrogen chain” whose result shows the chain is technically and economically feasible.

Growing attention to the environmental aspect has urged the effort to reduce CO2 emission as one of the greenhouse gases. The cement industry is one of the biggest CO2 emitters in this world. Alternative fuel is one of the challenging issues in cement production due to the limited fossil fuel resources and environmental concerns. Meanwhile hydrogen (H2) has been reported as a promising non-carbon fuel with ammonia (NH3) as the main candidate for chemical storage methods. In this work an integrated system of cement production with an alternative H2-based fuel is proposed consisting of the dehydrogenation process of NH3 and the H2 combustion to provide the required thermal energy for clinker production. Different catalysts are employed and evaluated to analyze the specific energy input (SEI). The result shows that the conversion rate strongly determines the SEI with minimum SEI (3829.8 MJ t-clinker-1 ) achieved by Ni-Pt-based catalyst at a reaction temperature of 600 ºC. Compared to the conventional fuel of coal the H2-based integrated cement production system shows a significant decrease of 44% in CO2 emission due to carbon-free combustion using H2 as the fuel. The current study on the proposed integrated system of H2-based cement production also provides an initial thermodynamic analysis and basic observation for the adoption of non-carbon-based H2 including the storage system of NH3 in the cement production process.

Renewable hydrogen is emerging as the key to a sustainable energy transition with multiple applications and uses. In the field of transport in addition to fuel cell vehicles it is necessary to develop an extensive network of hydrogen refueling stations (hereafter HRSs). The characteristics and properties of hydrogen make ensuring the safe operation of these facilities a crucial element for their successful deployment and implementation. This paper shows the outcomes of an analysis of hydrogen incidents and accidents considering their potential application to HRSs. For this purpose the HIAD 2.0 was reviewed and a total of 224 events that could be repeated in any of the major industrial processes related to hydrogen refueling stations were analyzed. This analysis was carried out using a mixed methodology of quantitative and qualitative techniques considering the following hydrogen value chain: production storage delivery and industrial use. The results provide general information segmented by event frequency damage classes and failure typology. The analysis shows the main processes of the value chain allow the identification of key aspects for the safety management of refueling facilities.

Polymeric materials are widely used in hydrogen energy system such as FCEV and hydrogen refueling stations under high-pressure condition. The permeation property (coefficients of permeation diffusion and solubility) of polymers under high-pressure hydrogen condition should be discussed as parameters to develop those devices. Also the property should be determined to understand influence of the compression by the pressure on polymer materials. A device which can measure gas permeation property of polymer materials accurately in equilibrium state under high-pressure environment is developed and the reliability of the measurements is ensured. High-pressure hydrogen gas permeability characteristics up to 100 MPa are measured for high-density polyethylene. An advantage of the method is discussed comparing with the non-equilibrium state method focusing on the hydrostatic pressure effect. Deterioration of hydrogen permeability is observed along with the decrease of diffusion coefficient which is supposedly affected by hydrostatic compression effect with the increase of environment pressure.

From navigating the rainbow of colours to the lack of consensus in establishing a common taxonomy the labelling and definition of green or renewable hydrogen presents a growing challenge. In this context carbon taxonomy is understood through five critical aspects: carbon intensity temporal and geographical correlation additionality of renewable energy generation and different system boundaries in Life Cycle Assessment (LCA). This study examines the effect of carbon taxonomy on the design and operation of Power-to-Gas (PtG) systems for renewable hydrogen production including the electricity supply portfolio via Power Purchase Agreements (PPA) and grid-connected electrolysis. To this end an optimisation model combining energy system modelling and LCA is developed and then applied to a case study in the Japanese context. The importance of the PPA portfolio in securing cheap and low-carbon electricity to produce hydrogen is addressed. To support this evaluation process an eco-efficiency metric is introduced and proved to be a comprehensive tool for evaluating renewable hydrogen production. Regarding carbon taxonomies the findings emphasize additionality as the key determinant factor followed by temporal correlation and the definition of carbon intensity thresholds. The application of a cradle-togate LCA boundary influenced the cabron intensity accounting playing an unexpected role on the design and optimal PtG dispatch strategy.

In addition to the promotion of pumped storage and electricity storage batteries the minimum use of inexpensive thermal power generation for the regulation of power in Japan and other countries is being considered as a supply-demand stabilization device with the expected widespread introduction of renewable energy by 2050. Therefore this study analyzed the economics related to the introduction of solid oxide fuel cell combined cycle using liquefied natural gas as a regulating power. The commercialization of recovered CO2 has been investigated for reducing the overall system operating costs. This study investigated a combined solid oxide fuel cell CO2 utilization system that employed green hydrogen methanolation and methanation to facilitate the use of the CO2 captured by the system. CO2 was separated from the exhaust gas of the system captured stored and used through methanation and methanolation. Consequently the synthesized methane was used for solid oxide fuel cell power generation and the synthesized methanol was sold. The discounted cash flow method was employed to evaluate the economic performance of the proposed system. At a unit price of 0.7–0.9 USD/kWh for electricity sold rated outputs of 1250 and 390 MW for solid oxide fuel cell combined cycle and photovoltaics respectively carbon capture and storage equipment cost of 800 USD/kWh and discount rate of 0.3 % the simple integrated payback period was obtained as 9 years whereas the dynamic payback period was 11–30 years. Consequently the economic feasibility of the proposed system was demonstrated.

Current hydrogen stations are using a constant dispenser pressure ramp rate method. When a flow rate increases for heavy duty vehicle a large pressure loss occurs and it slows down refueling. This study developed a new method (cTPR method) that has the constant pressure ramp rate in the tank by compensating for the tube pressure loss without any feedback from the vehicle. A refueling simulation confirmed that a refueling was shortened − 49s with a lower ending gas temperature. Testing confirmed that the cTPR method can be realized simply by changing the control without any hardware modification.

This paper aims to optimize dual-fuel facilitated off-/on-grid multi-energy systems (MESs) for different renewable energy zones (REZs) in Australia. The main objective is to develop a novel MES with the main feature of green hydrogen production and blended natural gas utilization for remote households. The proposed optimal system produces green hydrogen of 5343 kg/yr via proton exchange membrane (PEM) electrolyzer and blends it with natural gas. It involves 20 % hydrogen and 80 % natural gas in the overall volume of the blending process. This study contributes by performing optimal sizing of the components economic-energy-environmental and performance analyses to examine the most feasible solution for each REZ. The results indicate that the optimal system in North Queensland REZ has the lowest levelized cost of energy (LCE) of 1.28 A$/kWh and 0.1003 A $/kWh and the net present cost (NPC) of A$0.311 million and A$0.219 million for off-grid and on-grid configurations. The optimal on-grid system has 95.27 % less carbon emissions than the natural gas-fueled combustion energy system.

To achieve carbon neutrality in Japan by 2050 renewable energy needs to be used as the main energy source. Based on the constraints of various renewable energies the importance of hydrogen cannot be ignored. This study aimed to investigate the diffusion of hydrogen demand technologies in various sectors and used projections and assumptions to investigate the hydrogen supply side. By performing simulations with the E3ME-FTT model and comparing various policy scenarios with the reference scenario the economic and environmental impacts of the policy scenarios for hydrogen diffusion were analyzed. Moreover the impact of realizing carbon neutrality by 2050 on the Japanese economy was evaluated. Our results revealed that large-scale decarbonization via hydrogen diffusion is possible (90% decrease of CO2 emissions in 2050 compared to the reference) without the loss of economic activity. Additionally investments in new hydrogen-based and other low-carbon technologies in the power sector freight road transport and iron and steel industry can improve the gross domestic product (1.6% increase in 2050 compared to the reference) as they invoke economic activity and require additional employment (0.6% increase in 2050 compared to the reference). Most of the employment gains are related to decarbonizing the power sector and scaling up the hydrogen supply sector while a lot of job losses can be expected in the mining and fossil fuel industries.

Hydrogen addition affects the composition of exhaust gases in vehicles. However the effects of hydrogen addition to compression ignition engines in running vehicles have not been evaluated. Hydrogen‑mixed air was introduced into the air intake of a truck equipped with a direct‑ injection diesel engine and running on a chassis dynamometer to investigate the effect of hydrogen addition on fuel consumption and exhaust gas components. The reduction in diesel consumption and the increase in hydrogen energy share (HES) showed almost linear dependence where the percentage decrease in diesel consumption is approximately 0.6 × HES. The percentage reduction of CO2 showed a one‑to‑one relationship to the reduction in diesel consumption. The reduction in emissions of CO PM and hydrocarbons (except for ethylene) had one to one or a larger correlation with the reduction of diesel consumption. On the other hand it was observed that NOx emissions increased and the percentage increase of NOx was 1.5~2.0 times that of HES. The requirement for total energy supply was more when hydrogen was added than for diesel alone. In the actual running mode only 50% of the energy of added hydrogen was used to power the truck. As no adjustments were made to the engine in this experiment a possible disadvantage that could be improved by adjusting the combustion conditions.

The use of hydrogen fuel produced from renewable energy sources is an effective way to reduce well-to-wheel CO2 emissions from automobiles. In this study the performance of a hydrogen-powered series hybrid vehicle was compared with that of other powertrains such as gasoline-powered hybrid fuel cell and electric vehicles in a simulation that could estimate CO2 emissions under real-world driving conditions. The average fuel consumption of the hydrogenpowered series hybrid vehicle exceeded that of the gasoline-powered series hybrid vehicle under all conditions and was better than that of the fuel cell vehicle under urban and winding conditions with frequent acceleration and deceleration. The driving range was longer than that of the batterypowered vehicle but approximately 60% of that of the gasoline-powered series hybrid. Regarding the life-cycle assessment of CO2 emissions fuel cell and electric vehicles emitted more CO2 during the manufacturing process. Regarding fuel production CO2 emissions from hydrogen and electric vehicles depend on the energy source. However in the future this problem can be solved by using carbon-free energy sources for fuel production. Therefore hydrogen-powered series hybrid vehicles show a high potential to be environmentally friendly alternative fuel vehicles.

High-temperature proton exchange membranes (HT-PEMs) for fuel cells are considered transformative technologies for efficient energy conversion particularly in hydrogen-based transportation owing to their ability to deliver high power density and operational efficiency in harsh environments. However several critical challenges limit their broader adoption notably the limited durability and high costs associated with core components such as membranes and electrocatalysts under elevated temperature conditions. This review systematically addresses these challenges by examining the role of engineered nanomaterials in overcoming performance and stability limitations. The potential of nanomaterials to improve catalytic activity proton conductivity and thermal stability is discussed in detail emphasizing their impact on the optimization of catalyst layer composition including catalysts binders phosphoric acid electrolytes and additives. Recent advancements in nanostructured assemblies and 3D morphologies are explored to enhance fuel cell efficiency through synergistic interactions of these components. Additionally ongoing issues such as catalyst degradation long-term stability and resistance to high-temperature operation are critically analyzed. This manuscript offers a comprehensive overview of current HT-PEMs research and proposes future material design strategies that could bridge the gap between laboratory prototypes and large-scale industrial applications.

Deregulation in the energy sector has transformed the power systems with significant use of competition innovation and sustainability. This paper outlines a comparative study of renewable energy sources with electric vehicles (RES-EV) integration in a deregulated smart power system to highlight the learning on system efficiency effectiveness viability and the environment. This study depicts the importance of solar and wind energy in reducing carbon emissions and the challenges of integrating RES into present energy grids. It touches on the aspects of advanced energy storage systems demand-side management (DSM) and smart charging technologies for optimizing energy flows and stabilizing grids because of fluctuating demands. Findings were presented to show that based on specific pricing thresholds hybrid renewable energy systems can achieve grid parity and market competitiveness. Novel contributions included an in-depth exploration of the economic and technical feasibility of integrating EVs at the distribution level improvements in power flow control mechanisms and strategies to overcome challenges in decentralized energy systems. These insights will help policymakers and market participants make headway in the adoption of microgrids and smart grids within deregulated energy systems which is a step toward fostering a sustainable and resilient power sector.

The current study evaluates the feasibility of a forward osmosis membrane bioreactor (FO-MBR) for dark fermentation aiming at simultaneous biohydrogen production and wastewater treatment. Optimal microbial inoculation was achieved via heat-treated activated sludge enriching Clostridium sensu stricto 1 and yielding up to 2.21 mol H2.(mol hexose)− 1 in batch mode. In continuous operation a substrate concentration of 4.4 g L− 1 and a hydraulic retention time (HRT) of 12 h delivered the best results producing 1.51 mol H2.(mol hexosesupplied) − 1 . The FO-MBR configured with a 1.1 m2 hollow fiber side-stream membrane module and operated under dynamic HRT (2.5–12 h) dependent on membrane flux was integrated with intermittent CSTR (Continuous stirred tank reactor) operation to counter metabolite accumulation. This system outperformed a conventional CSTR achieving a hydrogen yield of 1.78 mol H2.(mol hexosesupplied) − 1 . Remarkable treatment efficiencies were observed with BOD5 COD and TOC removal rates of 95.32 % 99.02 % and 99.10 % respectively and an 83.8 % reduction in total waste volume. Additionally the FO-MBR demonstrated strong antifouling performance with 96.14 % water flux recovery achieved after a brief 5 min hydraulic rinse following 47.5 h of continuous highstrength broth exposure. These results highlight the FO-MBR system’s ability as a sustainable and highperformance alternative for integrated hydrogen production and effluent treatment. Further studies are recommended to address long-term fouling control and metabolite management for industrial scalability.

Scaling up water electrolyzers for green hydrogen production poses challenges in predicting megawatt-to gigawatt (MW/GW)-class system behavior under renewable energy power fluctuations. A fundamental evaluation is warranted to connect the characteristics of W- to kW-class laboratory electrolyzers with those of MW- to GW-class systems in practical applications. This study evaluates a 50 kW-class proton exchange membrane water electrolyzer with 30 cells using an accelerated degradation test protocol a simulated renewable energy power and a constant current of 800 A (1.33 A cm− 2 ) and the results show average degradation rates per cell of 40.4 27.2 and 5.6 μV h− 1 respectively. Evidently a voltage as approximate indicator exists for each cell to effectively suppress degradation. Durability tests reveal reductions in anode catalyst loading on the membrane electrode assemblies and inhomogeneous oxidation of the anode current collector. The findings contribute to predicting the stacking performance of electrolyzers for practical applications.

A compact hydrogen supply system for thermally integrating metal hydride (MH) tanks with a proton exchange membrane fuel cell (PEMFC) for a hydrogen-powered electric-assist bicycle (H-bike) is proposed. The system recovers the exhaust heat generated by the PEMFC to sustain hydrogen desorption and improve the system’s energy efficiency. The results demonstrate that the split-tank strategy decreases thermal and pressure gradients and enhances heat transfer and hydrogen release. The honeycomb tank configuration further improves hydrogen desorption by promoting uniform airflow distribution around each tank thereby improving exhaust heat utilization from the PEMFC. It employs a layer-adjustable configuration facilitating the flexible adaptation of MH cartridge quantities to meet hydrogen demand and prevailing road conditions in urban areas. Under a PEMFC power output of 215 W the system maintains a stable hydrogen flow rate for over 30 min with a heat recovery efficiency of 22.62 %. Furthermore increasing the number of MH cartridge layers significantly improves the thermal utilization of the system achieving a utilization efficiency of 39.90 % with two layers. These findings confirm the feasibility and scalability of the proposed system for H-bike highlighting its potential as a decentralized hydrogen supply solution for lightweight mobility and urban transportation applications.

Chemical looping hydrogen generation (CLHG) from biomass is a promising technology for producing carbonnegative hydrogen. However achieving autothermal operation without sacrificing hydrogen yield presents a significant thermodynamic challenge. This study proposes and evaluates a novel thermal management strategy that enables a self-sustaining process by balancing the system’s heat load with its internal exothermic reactions. A comprehensive analysis was conducted using process simulation to assess the system’s thermodynamic performance identify key sources of inefficiency through exergy analysis and determine its economic viability via a detailed techno-economic assessment. The results show that a 200 MWth CLHG plant can produce 2.06 t-H2/h with a hydrogen production efficiency and exergy efficiency of 34.46 % and 44.4 % respectively. The exergy analysis identified the fuel reactor as the largest source of thermodynamic inefficiency accounting for 66.4 % of the total exergy destruction. The techno-economic analysis yielded a base-case minimum selling price (MSP) of hydrogen of 2.63 USD/kg a rate competitive with other carbon-capture-enabled hydrogen production methods. Sensitivity analysis confirmed that the MSP is most influenced by biomass price and discount rate. Crucially the system’s carbon-negative nature allows it to leverage carbon pricing schemes which can significantly improve its economic performance. Under the EU’s current carbon price the MSP falls to 0.98 USD/kg-H2 and it can become negative in regions with higher carbon taxes suggesting profitability from carbon credits alone. This study demonstrates that the proposed CLHG system is a technically robust and economically compelling pathway for clean hydrogen production particularly in regulatory environments that incentivize carbon capture.

No countermeasures exist for accidents that might occur in hydrogen-based facilities (leaks fires explosions etc.). In South Korea discussions are underway regarding measures to ensure safety from such accidents such as the construction of underground hydrogen storage tank facilities. However explosion vents with a minimum ventilation area are required in such facilities to minimize damage to buildings and other structures due to accidental explosions. These explosion vents allow the generated overpressure and flames to be safely dispersed outside; however a safe separation distance must be secured to minimize damage to humans. This study aimed to determine the safe separation distance to minimize human damage after analyzing the dispersed overpressure and flame behavior following a vent explosion. Explosion experiments were conducted to investigate the influence of the ignition source location on internal and external overpressure and external flame behavior using a cuboid concrete structure with a volume of 20.33 m3 filled with a hydrogen-air mixture (29.0 vol.%). The impact on overpressure and flame was increased with the increasing distance of the ignition source from the vent. Importantly depending on the ignition location the incident pressure was up to 24.4 times higher while the reflected pressure was 8.7 times higher. Additionally a maximum external overpressure of 30.01 kPa was measured at a distance of 2.4 m from the vent predicting damage to humans at the “Injury” level (1 % fatality probability). Whereas no significant damage would occur at a distance of 7.4 m or more from the vent.

In this research we developed a hydrogen (H2 ) electric generator in an H2 generation system based on chemical reactions. In the experiment we tested the performance of the H2 electric generator and measured the amount of H2 generated. The maximum output was 700 W and the thermal efficiency was 18.2%. The theoretical value and measured value were almost the same and the maximum error was 4%.

Deploying renewable hydrogen presents a significant challenge in accessing off-takers who are willing to make long-term investments. To address this challenge current projects focus on large-scale deployment to replace the demand for non-renewable hydrogen particularly in ammonia synthesis for fertiliser production plants. The traditional process involving Steam Methane Reformers (SMR) connected to Haber-Bosch synthesis could potentially transition towards decarbonisation by gradually integrating water electrolysis. However the coexistence of these processes poses limitations in accommodating the integration of renewable hydrogen thereby creating operational challenges for industrial hubs. To tackle this issue this paper proposes an optimal dispatch model for producing green hydrogen and ammonia while considering the coexistence of different processes. Furthermore the objective is to analyse external factors that could determine the appropriate regulatory and pricing framework to facilitate the phase-out of SMR in favour of renewable hydrogen production. The paper presents a case study based in Spain utilising data from 2018 2022 and 2030 perspectives on the country's renewable resources gas and electricity wholesale markets pricing ranges and regulatory constraints to validate the model. The findings indicate that carbon emissions taxation and the availability and pricing of Power Purchase Agreements (PPAs) will play crucial roles in this transition - the carbon emission price required for total phasing out SMR with water electrolysis would be around 550 EUR/ton CO2.

Sunlight-driven water splitting allows renewable hydrogen to be produced from abundant and environmentally benign water. Large-scale societal implementation of this green fuel production technology within energy generation systems is essential for the establishment of sustainable future societies. Among various technologies photocatalytic water splitting using particulate semiconductors has attracted increasing attention as a method to produce large amounts of green fuels at low cost. The key to making this technology practical is the development of photocatalysts capable of splitting water with high solar-to-fuel energy conversion efficiency. Furthermore advances that enable the deployment of water-splitting photocatalysts over large areas are necessary as is the ability to recover hydrogen safely and efficiently from the produced oxyhydrogen gas. This lead article describes the key discoveries and recent research trends in photosynthesis using particulate semiconductors and photocatalyst sheets for overall water splitting via one-step excitation and two-step excitation (Z-scheme reactions) as well as for direct conversion of carbon dioxide into renewable fuels using water as an electron donor. We describe the latest advances in solar watersplitting and carbon dioxide reduction systems and pathways to improve their future performance together with challenges and solutions in their practical application and scalability including the fixation of particulate photocatalysts hydrogen recovery safety design of reactor systems and approaches to separately generate hydrogen and oxygen from water.

This study evaluates the potential for large-scale green hydrogen production in Indonesia by utilizing renewable energy sources connected on-grid namely 50 MWp of solar panels and 35 MW of wind turbines as well as a hybrid system combining both with a capacity of 45 MW at a grid cost of $100/kWh in five strategic cities: Banyuwangi Kupang BauBau Banjarmasin and Ambon. Using HOMER Pro software various integrated energy system scenarios involving ion exchange membrane electrolysis and alkaline water electrolysis. Additionally the study assumes a project lifespan of 15 years a discount rate of 6.6% and an inflation rate of 2.54%. The results showed that Bau-Bau recorded the highest hydrogen production reaching more than 1.9 million kilograms per year with the lowest levelized cost of hydrogen of $0.65/kg in Scheme 2. On the other hand Kupang shows high costs for most schemes with the levelized cost reaching $1.10/kg. In addition to hydrogen the study also evaluated oxygen production as a by-product of electrolysis. Bau-Bau and Kupang recorded the highest oxygen production with Scheme 6 achieving more than 15 million kilograms per year. The cost of electricity production varies between cities with Banyuwangi having the lowest cost of electricity for wind energy at $80.9/MWh. The net present cost for renewable energy systems in Banyuwangi was $35.4 million for wind turbines while the photovoltaic+wind combination showed the highest cost at $116 million. These findings emphasize the importance of hybrid systems in improving hydrogen production efficiency and supporting sustainable energy transition in Indonesia.

Australia has clear aspirations to become a major global exporter of hydrogen as a replacement for fossil fuels and as part of the drive to reduce CO2 emissions as set out in the National Hydrogen Strategy released in 2019 jointly by the federal and state governments. In 2021 the Australian Energy Market Operator specified a grid forecast scenario for the first time entitled “hydrogen superpower”. Not only does Australia hope to capitalise on the emerging demand for zero-carbon hydrogen in places like Japan and South Korea by establishing a new export industry but it also needs to mitigate the built-in carbon risk of its export revenue from coal and LNG as major customers such as Japan and South Korea move to decarbonise their energy systems. This places hydrogen at the nexus of energy climate change mitigation and economic growth with implications for energy security. Much of the published literature on this topic concentrates on the details of what being a major hydrogen exporter will look like and what steps will need to be taken to achieve it. However there appears to be a gap in the study of the implications for Australia’s domestic energy system in terms of energy security and export economic vulnerability. The objective of this paper is to develop a conceptual framework for the implications of becoming a major hydrogen exporter on Australia’s energy system. Various green hydrogen export scenarios for Australia were compared and the most recent and comprehensive was selected as the basis for further examination for domestic energy system impacts. In this scenario 248.5 GW of new renewable electricity generation capacity was estimated to be required by 2050 to produce the additional 867 TWh required for an electrolyser output of 2088 PJ of green hydrogen for export which will comprise 55.9% of Australia’s total electricity demand at that time. The characteristics of comparative export-oriented resources and their interactions with the domestic economy and energy system are then examined through the lens of the resource curse hypothesis and the LNG and aluminium industries. These existing resource export frameworks are reviewed for applicability of specific factors to export-oriented green hydrogen production with applicable factors then compiled into a novel conceptual framework for exporter domestic implications from large-scale exports of green hydrogen. The green hydrogen export superpower (2050) scenario is then quantitatively assessed using the established indicators for energy exporter vulnerability and domestic energy security comparing it to Australia’s 2019 energy exports profile. This assessment finds that in almost all factors exporter vulnerability is reduced and domestic energy security is enhanced by the transition from fossil fuel exports to green hydrogen with the exception of an increase in exposure of the domestic energy system to international market forces.

Social risk is a comprehensive concept that considers not only internal/external physical risks but also risks (which are multiple varied and diverse) associated with social activity. It should be considered from diverse perspectives and requires a comprehensive evaluation framework that takes into account the synergistic impact of each element on others rather than evaluating each risk individually. Social risk assessment is an approach that is not limited to internal system risk from an engineering perspective but also considers the stakeholders development stage and societal readiness and resilience to change. This study aimed to introduce a social risk approach to assess the public safety of large-scale hydrogen systems. Guidelines for comprehensive social risk assessment were developed to conduct appropriate risk assessments for advanced science and technology activities with high uncertainties to predict major impacts on society before an accident occurs and to take measures to mitigate the damage and to ensure good governance are in place to facilitate emergency response and recovery in addition to preventive measures. In a case study this approach was applied to a hydrogen refueling station in Japan and risk-based multidisciplinary approaches were introduced. These approaches can be an effective supporting tool for social implementation with respect to large-scale hydrogen systems such as liquefied hydrogen storage tanks. The guidelines for social risk assessment of large-scale hydrogen systems are under the International Energy Agency Technology Collaboration Program Hydrogen Safety Task 43. This study presents potential case studies of social risk assessment for large-scale hydrogen systems for future.

The shipping industry is currently the sixth largest contributor to global emissions responsible for one billion tons of greenhouse gas emissions. Urgent action is needed to achieve carbon neutrality in the shipping industry for sustainability. In this paper we use natural language processing techniques to analyze policies announcements and position papers from national and international organizations related to the decarbonization of shipping. In particular we perform the analysis using a novel matrix-based corpus and a fine-tuned machine learning model BERTopic. Our research suggests that the top four priorities for decarbonizing shipping are preventing emissions from methane leaks promoting non-carbon-based hydrogen implementing reusable modular containers to reduce packaging waste in container shipping and protecting Arctic biodiversity while promoting the Arctic shipping route to reduce costs. Our study highlights the validity of NLP techniques in quantitatively extracting critical information related to the decarbonization of the shipping industry.

Hydrogen recombination catalyst is useful tool for reducing hydrogen in closed area. The catalyst is known to be poisoned under wet condition in long time use. The study is focused on the behavior of pre-oxidized Pd nanoparticle as the hard-used catalyst in high humidity environment by comparison of alumina and titanium oxide supports using in situ X-ray absorption spectroscopy technique. The reduction of surface oxide layer of Pd/TiO2 was promoted by water during hydrogen recombination although the reduction reaction of Pd/Al2O3 was inhibited by water.

This study investigates the techno-economic feasibility of a Power-to-X (PtX) system by integrating solarpowered hydrogen electrolysis with carbon capture and Fischer-Tropsch (FT) synthesis processes for e-fuel production in Basra Iraq. To this aim a comprehensive modeling framework is developed to cover the detailed simulation of E-fuel production along with the system cost analysis. The proposed PtX system is supposed to be located near the Hartha power plant which is one of the main sources of electricity in the Basra region allowing for the utilization of captured CO2 from the power plant’s exhaust gas. The PtX plant design shows significant potential producing 2.44 tonnes of (C12-C20) hydrocarbons and 3.36 tonnes of (C21-C40) heavy oils annually. This is achieved by utilizing 7.5 and 74.2 tonnes per year of hydrogen generated from solar electrolysis and captured CO2 respectively. A cash flow analysis covering 25 years shows that an E-fuel market price of $10 per liter is needed to achieve a positive cash flow within 15 years. The study also indicates that implementing a $200 per tonne carbon tax improves the economic feasibility of the project by allowing for earlier positive cash flows from 6 years and a quicker break-even point at the current E-fuel market price of $2 per liter with a NPV of $ 464 million. Sensitivity analysis reveals that higher carbon taxes and e-fuel prices enhance profitability by reducing payback periods and increasing the NPV. However an increase in hydrogen production costs introduces substantial risk with higher costs decreasing economic viability. The feasibility assessment suggests that despite the substantial initial investment needed for various system components the long-term advantages include reduced CO2 emissions and the potential for Iraq to emerge as a leader in renewable fuel production. Stable policies robust carbon taxes and cost-efficient hydrogen production are essential for the successful implementation of PtX project.

The hydrogen compatibility of two X65 pipeline steels for transport of hydrogen gas is investigated through microstructural characterization hydrogen permeation measurements and fracture mechanical testing. The investigated materials are a quenched and tempered pipeline steel with a fine-grained homogeneously distributed ferrite-bainite microstructure and hot rolled pipeline steel with a ferrite-pearlite banded microstructure. All tests are performed both under electrochemical and gaseous hydrogen charging conditions. A correlation between electrochemical hydrogen charging and gaseous charging is determined. The results point to inherent differences in the interaction between hydrogen and the two material microstructures. Further research is needed to unveil the influence of material microstructure on hydrogen embrittlement.

Protonic solid oxide electrolysis cells are pivotal for environmentally sustainable hydrogen production via water splitting but suffer from efficiency losses due to partial hole conductivity. Here we introduce a device architecture based on a hydride-ion (H− )/proton (H+ ) bipolar electrolyte which exploits electrochemical rectification at a heteroionic interface to overcome this limitation. The perovskite-type BaZr0.5In0.5O2.75 electrolyte undergoes an in situ transformation under electrolysis conditions forming an H+ -conducting hydrate layer adjacent to the anode and an H− -conducting oxyhydride layer near the cathode governed by competitive thermodynamic equilibria of hydration and hydrogenation. This bipolar configuration enables high Faradaic currents through the superior H− ion conductivity of the oxyhydride phase stabilized by cathodic potentials while facilitating continuous H+ /H− interconversion at the interface. Furthermore electrochemical hydrogenation generates an electron-depleted interfacial layer that effectively suppresses hole conduction. Consequently the cells achieve efficiencies of ∼95% at 1.0 A cm− 2 surpassing conventional H+ unipolar designs.

The safe removal transportation and long-term storage of fuel debris in the decommissioning of Fukushima Daiichi is the biggest challenge facing Japan. In the nuclear power field passive autocatalytic recombiners (PARs) have become established as a technology to prevent hydrogen explosions inside the containment vessel. To utilize PAR as a measure to reduce the concentration of hydrogen generated in the fuel debris storage canister which is currently an issue it is required to perform in a sealed environment with high doses of radiation low temperature and high humidity and there are many challenges different from conventional PAR. A honeycombshaped catalyst based on automotive catalyst technology has been newly designed as a PAR and research has been conducted to solve unique problems such as high dose radiation low temperature high humidity coexistence of hydrogen and low oxygen and catalyst poisons. This paper summarizes the challenges of hydrogen generation in a sealed container the results of research and a guide to how to use the PAR for fuel debris storage canisters.

Natural hydrogen is generated via serpentinization radiolysis and organic metagenesis in geological settings. After expulsion from the source and along its upward migration path the free gas may encounter hydratebearing sediments. To simulate this natural scenario CH4 hydrate and CH4 + C3H8 hydrate were synthesized at 5.0 MPa and exposed to a hydrogen-containing gas mixture. In-situ Raman spectroscopic measurements demonstrated the incorporation of H2 molecules into the hydrate phase even at a partial pressure of 0.5 MPa. Exsitu Raman spectroscopic characterization of hydrates formed from a CH4 + H2 gas mixture at 5.0 MPa confirmed the H2 inclusion within the large cavities of structure I. The results show that the interactions between H2 and the natural gas hydrate phase range from the incorporation of H2 molecules into the hydrate phase to the rapid dissociation of the gas hydrate depending on thermodynamic conditions and H2 concentration in the coexisting gas phase.

This study presents a techno-economic framework for assessing the potential of utilizing hybrid renewable energy sources (wind and solar) to produce green hydrogen with a specific focus on Australia. The model’s objective is to equip decision-makers in the green hydrogen industry with a reliable methodology to assess the availability of renewable resources for cost-effective hydrogen production. To enhance the credibility of the analysis the model integrates 10 min on-ground solar and wind data uses a high-resolution power dispatch simulation and considers electrolyzer operational thresholds. This study concentrates on five locations in Australia and employs high-frequency resource data to quantify wind and solar availability. A precise simulation of power dispatch for a large off-grid plant has been developed to analyze the PV/wind ratio element capacities and cost variables. The results indicate that the locations where wind turbines can produce cost-effective hydrogen are limited due to the high capital investment which renders wind farms uneconomical for hydrogen production. Our findings show that only one location—Edithburgh South Australia—under a 50% solar–50% wind scenario achieves a hydrogen production cost of 10.3 ¢USD/Nm3 which is lower than the 100% solar scenario. In the other four locations the 100% solar scenario proves to be the most cost-effective for green hydrogen production. This study suggests that precise and comprehensive resource assessment is crucial for developing hydrogen production plants that generate low-cost green hydrogen.