Japan
Pressure Dependence of CO2 Effect on Hydrogen-assisted Fatigue Crack Growth in Two Pipeline Steels
Oct 2024
Publication
This study investigated the pressure-dependent CO2 effect on the hydrogen embrittlement of X80 and GB20# pipeline steels by combining experiments and first-principles calculations. Results revealed that the CO2 effect enhanced the fatigue crack growth for GB20# steel in 10 MPa CO₂-enriched hydrogen mixtures. However the improved degree by the CO₂ effect at 10 MPa was less pronounced than at 0.4 MPa which was found for the first time. This was attributed to the decreased adsorption rate of CO₂ on iron as hydrogen pressure increased. Therefore in high-pressure CO₂-enriched hydrogen mixtures CO2 could not significantly accelerate the inherent rapid hydrogen uptake at high pressure.
Potential Domestic Energy System Vulnerabilities from Major Exports of Green Hydrogen: A Case Study of Australia
Aug 2023
Publication
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.
Economic Analysis of a Photovoltaic Hydrogen Refueling Station Based on Hydrogen Load
Sep 2023
Publication
With the goal of achieving “carbon peak in 2030 and carbon neutrality in 2060” as clearly proposed by China the transportation sector will face long–term pressure on carbon emissions and the application of hydrogen fuel cell vehicles will usher in a rapid growth period. However true “zero carbon” emissions cannot be separated from “green hydrogen”. Therefore it is of practical significance to explore the feasibility of renewable energy hydrogen production in the context of hydrogen refueling stations especially photovoltaic hydrogen production which is applied to hydrogen refueling stations (hereinafter referred to “photovoltaic hydrogen refueling stations”). This paper takes a hydrogen refueling station in Shanghai with a supply capacity of 500 kg/day as the research object. Based on a characteristic analysis of the hydrogen demand of the hydrogen refueling station throughout the day this paper studies and analyzes the system configuration operation strategy environmental effects and economics of the photovoltaic hydrogen refueling station. It is estimated that when the hydrogen price is no less than 6.23 USD the photovoltaic hydrogen refueling station has good economic benefits. Additionally compared with the conventional hydrogen refueling station it can reduce carbon emissions by approximately 1237.28 tons per year with good environmental benefits.
Social Risk Approach for Assessing Public Safety of Large-scale Hydrogen Systems
Sep 2023
Publication
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.
Temporally Detailed Modeling and Analysis of Global Net Zero Energy Systems Focussing on Variable Renewable Energy
Apr 2023
Publication
This study newly develops a recursive-dynamic global energy model with an hourly temporal resolution for electricity and hydrogen balances aiming to assess the role of variable renewable energy (VRE) in a carbonneutral world. This model formulated as a large-scale linear programming model (with 500 million each of variables and constraints) calculates the energy supply for 100 regions by 2050. The detailed temporal reso lution enables the model to incorporate the variable output of VRE and system integration options such as batteries water electrolysis curtailment and the flexible charging of battery electric vehicles. Optimization results suggest that combing various technical options suitable for local energy situations is critical to reducing global CO2 emissions cost-effectively. Not only VRE but also CCS-equipped gas-fired and biomass-fired power plants largely contribute to decarbonizing power supply. The share of VRE in global power generation in 2050 is estimated to be 57% in a cost-effective case. The results also imply economic challenges for an energy system based on 100% renewable energy. For example the average mitigation cost in 2050 is 69USD/tCO2 in the costeffective case while it increases to 139USD/tCO2 in the 100% renewable case. The robustness of this argument is tested by sensitivity analyses.
Exploring Decarbonization Priorities for Sustainable Shipping: A Natural Language Processing-based Experiment
Oct 2024
Publication
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.
Science and Technology of Ammonia Combustion
Nov 2018
Publication
This paper focuses on the potential use of ammonia as a carbon-free fuel and covers recent advances in the development of ammonia combustion technology and its underlying chemistry. Fulfilling the COP21 Paris Agreement requires the de-carbonization of energy generation through utilization of carbon-neutral and overall carbon-free fuels produced from renewable sources. Hydrogen is one of such fuels which is a potential energy carrier for reducing greenhouse-gas emissions. However its shipment for long distances and storage for long times present challenges. Ammonia on the other hand comprises 17.8% of hydrogen by mass and can be produced from renewable hydrogen and nitrogen separated from air. Furthermore thermal properties of ammonia are similar to those of propane in terms of boiling temperature and condensation pressure making it attractive as a hydrogen and energy carrier. Ammonia has been produced and utilized for the past 100 years as a fertilizer chemical raw material and refrigerant. Ammonia can be used as a fuel but there are several challenges in ammonia combustion such as low flammability high NOx emission and low radiation intensity. Overcoming these challenges requires further research into ammonia flame dynamics and chemistry. This paper discusses recent successful applications of ammonia fuel in gas turbines co-fired with pulverize coal and in industrial furnaces. These applications have been implemented under the Japanese ‘Cross-ministerial Strategic Innovation Promotion Program (SIP): Energy Carriers’. In addition fundamental aspects of ammonia combustion are discussed including characteristics of laminar premixed flames counterflow twin-flames and turbulent premixed flames stabilized by a nozzle burner at high pressure. Furthermore this paper discusses details of the chemistry of ammonia combustion related to NOx production processes for reducing NOx and validation of several ammonia oxidation kinetics models. Finally LES results for a gas-turbine-like swirl-burner are presented for the purpose of developing low-NOx single-fuelled ammonia gas turbine combustors.
X-ray Absorpton Spectroscopy Study on Hydrogen Recombination Catalysts of Palladium Nanoparticles on Titanium Oxide under Wet Condition
Sep 2023
Publication
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.
Innovations in Hydrogen Storage Materials: Synthesis, Applications, and Prospects
Jul 2024
Publication
Hydrogen globally recognized as the most efficient and clean energy carrier holds the potential to transform future energy systems through its use as a fuel and chemical resource. Although progress has been made in reversible hydrogen adsorption and release challenges in storage continue to impede widespread adoption. This review explores recent advancements in hydrogen storage materials and synthesis methods emphasizing the role of nanotechnology and innovative synthesis techniques in enhancing storage performance and addressing these challenges to drive progress in the field. The review provides a comprehensive overview of various material classes including metal hydrides complex hydrides carbon materials metal-organic frameworks (MOFs) and porous materials. Over 60 % of reviewed studies focused on metal hydrides and alloys for hydrogen storage. Additionally the impact of nanotechnology on storage performance and the importance of optimizing synthesis parameters to tailor material properties for specific applications are summarized. Various synthesis methods are evaluated with a special emphasis on the role of nanotechnology in improving storage performance. Mechanical milling emerges as a commonly used and cost-effective method for fabricating intermetallic hydrides capable of adjusting hydrogen storage properties. The review also explores hydrogen storage tank embrittlement mechanisms particularly subcritical crack growth and examines the advantages and limitations of different materials for various applications supported by case studies showcasing real-world implementations. The challenges underscore current limitations in hydrogen storage materials highlighting the need for improved storage capacity and kinetics. The review also explores prospects for developing materials with enhanced performance and safety providing a roadmap for ongoing advancements in the field. Key findings and directions for future research in hydrogen storage materials emphasize their critical role in shaping future energy systems.
Power-to-X in Southern Iraq: Techno-economic Assessment of Solar-powered Hydrogen Electrolysis Combined with Carbon Capture and Storage for Sustainable Energy Solutions
Feb 2025
Publication
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.
Mid-century Net-zero Emissions Pathways for Japan: Potential Roles of Global Mitigation Scenarios in Informing National Decarbonisation Strategies
Jan 2024
Publication
Japan has formulated a net-zero emissions target by 2050. Existing scenarios consistent with this target generally depend on carbon dioxide removal (CDR). In addition to domestic mitigation actions the import of low-carbon energy carriers such as hydrogen and synfuels and negative emissions credits are alternative options for achieving net-zero emissions in Japan. Although the potential and costs of these actions depend on global energy system transition characteristics which can potentially be informed by the global integrated assessment models they are not considered in current national scenario assessments. This study explores diverse options for achieving Japan's net-zero emissions target by 2050 using a national energy system model informed by international energy trade and emission credits costs estimated with a global energy system model. We found that demand-side electrification and approximately 100 Mt-CO2 per year of CDR implementation equivalent to approximately 10% of the current national CO2 emissions are essential across all net-zero emissions scenarios. Upscaling of domestically generated hydrogen-based alternative fuels and energy demand reduction can avoid further reliance on CDR. While imports of hydrogen-based energy carriers and emission credits are effective options annual import costs exceed the current cost of fossil fuel imports. In addition import dependency reaches approximately 50% in the scenario relying on hydrogen imports. This study highlights the importance of considering global trade when developing national net-zero emissions scenarios and describes potential new roles for global models.
Safe Pipelines for Hydrogen Transport
Jun 2024
Publication
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.
Global Demand for Green Hydrogen-based Steel: Insights from 28 Scenarios
Jul 2024
Publication
Growing expectations are being placed on green hydrogen-based steel for decarbonising the global steel industry. However the scale of the expected demand is dispersed across numerous case studies resulting in a fragmented picture. This study examines 28 existing scenarios to provide a cohesive view of future global demand. In the short term the demand for green hydrogen-based steel is expected to be limited constituting 2% of current total steel production by 2030. However a transformation phase is expected around 2040 marked by accelerated growth. By 2050 global demand is projected to reach 660 Mt (with an interquartile range of 368–1000 Mt) equivalent to 35% (19%–53%) of current total steel production. To meet such growing demand green hydrogen supply and electrolyser capacity will need to increase to more than 1000 times current levels by 2050. These trends highlight both short-term limitations and long-term potential. Decarbonisation efforts will therefore require immediate emission reductions with already scalable options while simultaneously building the enabling infrastructure for green hydrogen-based steelmaking to ensure long-term impacts.
Bipolar Electrolysis Cells with Hydride Ion-proton Conductor Heterejunctions
Oct 2025
Publication
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.
Optimizing Vietnam's Hydrogen Strategy: A Life-cycle Perspective on Technology Choices, Environmental Impacts, and Cost Trade-offs
Sep 2025
Publication
Vietnam recognizes hydrogen as a key fuel for decarbonization under its National Hydrogen Strategy. Here we quantified the environmental and economic performance of Vietnam’s optimal hydrogen-production pathways by evaluating combinations of green and blue hydrogen under varying demand scenarios using life-cycle assessment and optimization modeling techniques. The environmental performance of hydrogen production proved highly sensitive to the electricity source with water electrolysis powered by renewable energy offering the most favorable outcomes. Although green hydrogen production reduced carbon emissions it shifted environmental burdens toward increased resource extraction. Producing 20 Mt of hydrogen by 2050 would require 741.56 TWh of electricity 178 Mt of water and USD 294 billion in investment and it would emit 50.48 Mt CO2. These findings highlight the importance of strategic hydrogen planning and resource strategy aligned with national priorities for energy transition to navigate trade-offs among technology selection emissions costs and resource consumption.
A Proposal of Hydrogen Safety Technology for Decommissioning of the Fukushima Daiichi Nuclear Power Station
Mar 2025
Publication
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.
Emerging Application of Solid Oxide Electrolysis Cells in Hydrogen Production: A Comprehensive Analytic Review and Life Cycle Assessment
Aug 2025
Publication
This paper provides a comprehensive analytical review and life cycle assessment (LCA) of solid oxide electrolysis cells (SOECs) for hydrogen production. As the global energy landscape shifts toward cleaner and more sustainable solutions SOECs offer a promising pathway for hydrogen generation by utilizing water as a feedstock. Despite their potential challenges in efficiency economic viability and technological barriers remain. This review explores the evolution of SOECs highlighting key advancements and innovations over time and examines their operational principles efficiency factors and classification by operational temperature range. It further addresses critical technological challenges and potential breakthroughs alongside an indepth assessment of economic feasibility covering production cost comparisons hydrogen storage capacity and plant viability and an LCA evaluating environmental impacts and sustainability. The findings underscore SOECs’ progress and their crucial role in advancing hydrogen production while pointing to the need for further research to overcome existing limitations and enhance commercial viability.
Interactions Between Gas Hydrate and Hydrogen in Nature: Laboratory Evidence of Hydrogen Incorporation
Oct 2025
Publication
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.
Ammonia Decomposition and Hydrogen Production via Novel FeCoNiCuMnO High-entropy Ceramic Catalysts
Oct 2025
Publication
Ammonia (NH3) decomposition offers a pathway for water purification and green hydrogen production yet conventional catalysts often suffer from poor stability due to agglomeration. This study presents a novel (FeCoNiCuMn)O high-entropy ceramic (HEC) catalyst synthesized via fast-moving bed pyrolysis (FMBP) which prevents aggregation and enhances catalytic performance. The HEC catalyst applied as an anode in electrochemical oxidation (EO) demonstrated a uniform spinel (AB2O4) structure confirmed by XRD XRF and ICP-OES. Electronic structure characterization using UPS and LEIPS revealed a bandgap of 4.722 eV with EVBM and ECBM values facilitating redox reactions. Under 9 V and 50 mA/cm² current density the HEC electrode achieved 99% ammonia decomposition within 90 min and retained over 90% efficiency after four cycles. Surface analysis by XPS and HAXPES indicated oxidation state variations confirming catalyst activity and stability. Gas chromatography identified H2 N2 and O2 as the main products with ~64.7% Faradaic efficiency for H2 classifying it as green hydrogen. This dual-function approach highlights the (FeCoNiCuMn)O HEC anode as a promising and sustainable solution for wastewater treatment and hydrogen production.
Techno-Economic Assessment of Green Hydrogen Production in Australia Using Off-Grid Hybrid Resources of Solar and Wind
Jun 2025
Publication
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.
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