Japan
Interfacial Fracture Strength Property of Micro-scale SiN/Cu Components
Jul 2016
Publication
The strength against fracture nucleation from an interface free-edge of silicon-nitride (SiN)/copper (Cu) micro-components is evaluated. A special technique that combines a nano-indenter specimen holder and an environmental transmission electron microscope (E-TEM) is employed. The critical load at the onset of fracture nucleation from a wedge-shaped free-edge (opening angle: 90°) is measured both in a vacuum and in a hydrogen (H2) environment and the critical stress distribution is evaluated by the finite element method (FEM). It is found that the fracture nucleation is dominated by the near-edge elastic singular stress field that extends about a few tens of nanometers from the edge. The fracture nucleation strength expressed in terms of the stress intensity factor (K) is found to be eminently reduced in a H2 environment.
Liquid Hydrogen as Prospective Energy Carrier: A Brief Review and Discussion of Underlying Assumptions Applied in Value Chain Analysis
Nov 2021
Publication
In the literature different energy carriers are proposed in future long-distance hydrogen value chains. Hydrogen can be stored and transported in different forms e.g. as compressed dense-phase hydrogen liquefied hydrogen and in chemically bound forms as different chemical hydrides. Recently different high-level value chain studies have made extrapolative investigations and compared such options with respect to energy efficiency and cost. Three recent journal papers overlap as the liquid hydrogen option has been considered in all three studies. The studies are not fully aligned in terms of underlying assumptions and battery limits. A comparison reveals partly vast differences in results for chain energy efficiency for long-distance liquid hydrogen transport which are attributable to distinct differences in the set of assumptions. Our comparison pinpoints the boiloff ratio i.e. evaporation losses due to heat ingress in liquid hydrogen storage tanks as the main cause of the differences and this assumption is further discussed. A review of spherical tank size and attributed boiloff ratios is presented for existing tanks of different vintage as well as for recently proposed designs. Furthermore the prospect for further extension of tanks size and reduction of boiloff ratio is discussed with a complementary discussion about the use of economic assumptions in extrapolative and predictive studies. Finally we discuss the impact of battery limits in hydrogen value chain studies and pinpoint knowledge needs and the need for a detailed bottom-up approach as a prerequisite for improving the understanding for pros and cons of the different hydrogen energy carriers.
Public Acceptance for the Implementation of Hydrogen Self-refueling Stations
Sep 2021
Publication
The utilization of hydrogen energy is important for achieving a low-carbon society. Japan has set ambitious goals for hydrogen stations and fuel cell vehicles focusing on the introduction and dissemination of self-refuelling systems. This paper evaluates public trust in the fuel equipment and self-handling technology related to self-refuelling hydrogen stations and compares it with that for widespread gasoline stations. To this end the results of an online survey of 300 people with Japanese driver licenses are reported and analyzed. The results show that trust in the equipment and self-handling is more important for the user than trust in the fuel. In addition to introduce and disseminate new technology such as hydrogen stations users must be made aware of the risk of using the technology until it becomes as familiar as existing gasoline station technology.
Roadmap to Hybrid Offshore System with Hydrogen and Power Co-generation
Sep 2021
Publication
Constrained by the expansion of the power grid the development of offshore wind farms may be hindered and begin to experience severe curtailment or restriction. The combination of hydrogen production through electrolysis and hydrogen-to-power is considered to be a potential option to achieve the goal of low-carbon and energy security. This work investigates the competitiveness of different system configurations to export hydrogen and/or electricity from offshore plants with particular emphasis on unloading the mixture of hydrogen and electricity to end-users on land. Including the levelized energy cost and net present value a comprehensive techno-economic assessment method is proposed to analyze the offshore system for five scenarios. Assuming that the baseline distance is 10 km the results show that exporting hydrogen to land through pipelines shows the best economic performance with the levelized energy cost of 3.40 $/kg. For every 10 km increase in offshore distance the net present value of the project will be reduced by 5.69 MU$ and the project benefit will be positive only when the offshore distance is less than 53.5 km. An important finding is that the hybrid system under ship transportation mode is not greatly affected by the offshore distance. Every 10% increase in the proportion of hydrogen in the range of 70%–100% can increase the net present value by 1.43–1.70 MU$ which will increase by 7.36–7.37 MU$ under pipeline transportation mode. Finally a sensitivity analysis was carried out to analyze the wind speed electricity and hydrogen prices on the economic performance of these systems.
The Impact of Operating Conditions on the Performance of a CH4 Dry Reforming Membrane Reactor for H2 Production
May 2020
Publication
Biogas is a promising resource for the production of H2 since it liberates energy by recycling waste along with the reduction of CO2. In this paper the biogas dry reforming membrane reactor is proposed to produce H2 for use in fuel cells. Pd/Cu alloy membrane is used to enhance the performance of the biogas dry reforming reactor. This study aims at understanding the effect of operating parameters such as feed ratio of sweep gas pressure in the reactor and reaction temperature on the performance of the biogas dry reforming membrane reactor. The effect of the molar ratio of the supplied CH4:CO2 feed ratio of the sweep gas and the valve located at the outlet of the reaction chamber on the performance of biogas dry reforming are investigated. Besides the thermal efficiency of the proposed reactor is also evaluated. The results show that the concentration of H2 in the closed valve condition is higher than that of the open valve and the optimum feed ratio of the sweep gas to produce H2 is 1 irrespective of the molar ratio of supplied CH4:CO2. Also H2 selectivity and CO selectivity increases and decreases respectively when the reaction temperature increases irrespective of the molar ratio of supplied CH4:CO2. Therefore the thermal efficiency of the closed valve is higher than that of the opened valve. Also the thermal efficiency is the maximum when the feed ratio of the sweep gas is 1 due to high H2 production performance.
Scenario-Based Comparative Analysis for Coupling Electricity and Hydrogen Storage in Clean Oilfield Energy Supply System
Mar 2022
Publication
In response to the objective of fully attaining carbon neutrality by 2060 people from all walks of life are pursuing low-carbon transformation. Due to the high water cut in the middle and late phases of development the oilfield’s energy consumption will be quite high and the rise in energy consumption will lead to an increase in carbon emission at the same time. As a result the traditional energy model is incapable of meeting the energy consumption requirement of high water cut oilfields in their middle and later phases of development. The present wind hydrogen coupling energy system was researched and coupled with the classic dispersed oilfield energy system to produce energy for the oilfields in this study. This study compares four future energy system models to existing ones computes the energy cost and net present value of an oilfield in Northwest China and proposes a set of economic evaluation tools for oilfield energy systems. The study’s findings indicate that scenario four provides the most economic and environmental benefits. This scenario effectively addresses the issue of high energy consumption associated with aging oilfields at this point significantly reduces carbon emissions absorbs renewable energy locally and reduces the burden on the power grid system. Finally sensitivity analysis is utilized to determine the effect of wind speed electricity cost and oilfield gas output on the system’s economic performance. The results indicate that the system developed in this study can be applied to other oilfields.
Sustainable Offshore Oil and Gas Fields Development: Techno-economic Feasibility Analysis of Wind–hydrogen–natural Gas Nexus
Jul 2021
Publication
Offshore oil and gas field development consumes quantities of electricity which is usually provided by gas turbines. In order to alleviate the emission reduction pressure and the increasing pressure of energy saving governments of the world have been promoting the reform of oil and gas fields for years. Nowadays environmentally friendly alternatives to provide electricity are hotspots such as the integration of traditional energy and renewable energy. However the determination of system with great environmental and economic benefits is still controversial. This paper proposed a wind– hydrogen–natural gas nexus (WHNGN) system for sustainable offshore oil and gas fields development. Combining the optimization model with the techno-economic evaluation model a comprehensive evaluation framework is established for techno-economic feasibility analysis. In addition to WHNGN system another two systems are designed for comparison including the traditional energy supply (TES) system and wind–natural gas nexus (WNGN) system. An offshore production platforms in Bohai Bay in China is taken as a case and the results indicate that: (i) WNGN and WHNGN systems have significant economic benefits total investment is decreased by 5190 and 5020 million $ respectively and the WHNGN system increases 4174 million $ profit; (ii) WNGN and WHNGN systems have significant environmental benefits annual carbon emission is decreased by 15 and 40.2 million kg respectively; (iii) the system can be ranked by economic benefits as follows: WHNGN >WNGN > TES; and (iV) the WHNGN system is more advantageous in areas with high hydrogen and natural gas sales prices such as China Kazakhstan Turkey India Malaysia and Indonesia.
Role of Hydrogen-based Energy Carriers as an Alternative Option to Reduce Residual Emissions Associated with Mid-century Decarbonization Goals
Mar 2022
Publication
Hydrogen-based energy carriers including hydrogen ammonia and synthetic hydrocarbons are expected to help reduce residual carbon dioxide emissions in the context of the Paris Agreement goals although their potential has not yet been fully clarified in light of their competitiveness and complementarity with other mitigation options such as electricity biofuels and carbon capture and storage (CCS). This study aimed to explore the role of hydrogen in the global energy system under various mitigation scenarios and technology portfolios using a detailed energy system model that considers various energy technologies including the conversion and use of hydrogen-based energy carriers. The results indicate that the share of hydrogen-based energy carriers generally remains less than 5% of global final energy demand by 2050 in the 2 ◦C scenarios. Nevertheless such carriers contribute to removal of residual emissions from the industry and transport sectors under specific conditions. Their share increases to 10–15% under stringent mitigation scenarios corresponding to 1.5 ◦C warming and scenarios without CCS. The transport sector is the largest consumer accounting for half or more of hydrogen production followed by the industry and power sectors. In addition to direct usage of hydrogen and ammonia synthetic hydrocarbons converted from hydrogen and carbon captured from biomass or direct air capture are attractive transport fuels growing to half of all hydrogen-based energy carriers. Upscaling of electrification and biofuels is another common cost-effective strategy revealing the importance of holistic policy design rather than heavy reliance on hydrogen.
Hydrogen Generation from Wood Chip and Biochar by Combined Continuous Pyrolysis and Hydrothermal Gasification
Jun 2021
Publication
Hydrothermal gasification (HTG) experiments were carried out to extract hydrogen from biomass. Although extensive research has been conducted on hydrogen production with HTG limited research exists on the use of biochar as a raw material. In this study woodland residues (wood chip) and biochar from wood-chip pyrolysis were used in HTG treatment to generate hydrogen. This research investigated the effect of temperature (300–425 °C) and biomass/water (0.5–10) ratio on gas composition. A higher temperature promoted hydrogen production because the water–gas shift reaction and steam-reforming reaction were promoted with an increase in temperature. The methane concentration was related positively to temperature because of the methanation and hydrogenation reactions. A lower biomass/water ratio promoted hydrogen production but suppressed carbon-monoxide production. Most reactions that produce hydrogen consume water but water also affects the water–gas shift reaction balance which decreases the carbon-monoxide concentration. By focusing on the practical application of HTG we attempted biochar treatment by pyrolysis (temperature of heating part: 700 °C) and syngas was obtained from hydrothermal treatment above 425 °C.
Environmental and Energy Life Cycle Analyses of Passenger Vehicle Systems Using Fossil Fuel-derived Hydrogen
Sep 2021
Publication
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.
Challenges Toward Achieving a Successful Hydrogen Economy in the US: Potential End-use and Infrastructure Analysis to the Year 2100
Jul 2022
Publication
Fossil fuels continue to exacerbate climate change due to large carbon emissions resulting from their use across a number of sectors. An energy transition away from fossil fuels seems inevitable and energy sources such as renewables and hydrogen may provide a low carbon alternative for the future energy system particularly in large emitting nations such as the United States. This research quantifies and maps potential hydrogen fuel distribution pathways for the continental US reflecting technological changes barriers to deployment and end-use-cases from 2020 to 2100 clarifying the potential role of hydrogen in the US energy transition. The methodology consists of two parts a linear optimization of the global energy system constrained by carbon reduction targets and system cost followed by a projection of hydrogen infrastructure development. Key findings include the emergence of trade pattern diversification with a greater variety of end-uses associated with imported fuels and greater annual hydrogen consumption over time. Further sensitivity analysis identified the influence of complementary technologies including nuclear power and carbon capture and storage technologies. We conclude that hydrogen penetration into the US energy system is economically viable and can contribute toward achieving Paris Agreement and more aggressive carbon reduction targets in the future.
Impact and Challenges of Reducing Petroleum Consumption for Decarbonization
Apr 2022
Publication
This study aimed to identify the impact of achieving the 1.5 ◦C target on the petroleum supply chain in Japan and discuss the feasibility and challenges of decarbonization. First a national material flow was established for the petroleum supply chain in Japan including processes for crude petroleum refining petroleum product manufacturing plastic resin and product manufacturing and by-product manufacturing. In particular by-product manufacturing processes such as hydrogen gaseous carbon dioxide and sulfur were selected because they are utilized in other industries. Next the outlook for the production of plastic resin hydrogen dry ice produced from carbon dioxide gas and sulfur until 2050 was estimated for reducing petroleum consumption required to achieve the 1.5 ◦C target. As a result national petroleum treatment is expected to reduce from 177048.00 thousand kl in 2019 to 126643.00 thousand kl in 2030 if the reduction in petroleum consumption is established. Along with this decrease plastic resin production is expected to decrease from 10500.00 thousand ton in 2019 to 7511.00 thousand ton by 2030. Conversely the plastic market is expected to grow steadily and the estimated plastic resin production in 2030 is expected to be 20079.00 thousand ton. This result indicates that there is a large output gap between plastic supply and demand. To mitigate this gap strongly promoting the recycling of waste plastics and making the price competitiveness of biomass plastics equal to that of petroleum-derived plastics are necessary
Quantitative Monitoring of the Environmental Hydrogen Embrittlement of Al-Zn-Mg-based Aluminum Alloys via Dnyamic Hydrogen Detection and Digital Image Correlation
Mar 2021
Publication
In this study a novel analytical system was developed to monitor the environmental hydrogen embrittlement of Al-Zn-Mg-based aluminum alloys dynamically and quantitatively under atmospheric air pressure. The system involves gas chromatography using a SnO2-based semiconductor hydrogen sensor a digital image correlation step and the use of a slow strain rate testing machine. Use of this system revealed that hydrogen atoms are generated during the plastic deformation of Al-Zn-Mg alloys caused by the chemical reaction between the water vapor in air and the alloy surface without oxide films. Digital image correlation also clarified that the generated hydrogen atoms caused numerous localized grain boundary cracks on the specimen surface resulting in a localized grain boundary fracture. The amount of hydrogen atoms evolved from the embrittled fracture surface was 2.7 times as high as that from the surface without embrittlement.
Blast Wave Generated by Delayed Ignition of Under-Expanded Hydrogen Free Jet at Ambient and Cryogenic Temperatures
Nov 2022
Publication
An under-expanded hydrogen jet from high-pressure equipment or storage tank is a potential incident scenario. Experiments demonstrated that the delayed ignition of a highly turbulent under-expanded hydrogen jet generates a blast wave able to harm people and damage property. There is a need for engineering tools to predict the pressure effects during such incidents to define hazard distances. The similitude analysis is applied to build a correlation using available experimental data. The dimensionless blast wave overpressure generated by delayed ignition and the follow-up deflagration or detonation of hydrogen jets at an any location from the jet ∆Pexp/P0 is correlated to the original dimensionless parameter composed of the product of the dimensionless ratio of storage pressure to atmospheric pressure Ps/P0 and the ratio of the jet release nozzle diameter to the distance from the centre of location of the fast-burning near-stoichiometric mixture on the jet axis (30% of hydrogen in the air by volume) to the location of a target (personnel or property) d/Rw. The correlation is built using the analysis of 78 experiments regarding this phenomenon in the wide range of hydrogen storage pressure of 0.5–65.0 MPa and release diameter of 0.5–52.5 mm. The correlation is applicable to hydrogen free jets at ambient and cryogenic temperatures. It is found that the generated blast wave decays inversely proportional to the square of the distance from the fast-burning portion of the jet. The correlation is used to calculate the hazard distances by harm thresholds for five typical hydrogen applications. It is observed that in the case of a vehicle with onboard storage tank at pressure 70 MPa the “no-harm” distance for humans reduces from 10.5 m to 2.6 m when a thermally activated pressure relief device (TPRD) diameter decreases from 2 mm to a diameter of 0.5 mm.
New Insights into Hydrogen Uptake on Porous Carbon Materials via Explainable Machine Learning
Apr 2021
Publication
To understand hydrogen uptake in porous carbon materials we developed machine learning models to predict excess uptake at 77 K based on the textural and chemical properties of carbon using a dataset containing 68 different samples and 1745 data points. Random forest is selected due to its high performance (R2 > 0.9) and analysis is performed using Shapley Additive Explanations (SHAP). It is found that pressure and Brunauer-Emmett-Teller (BET) surface area are the two strongest predictors of excess hydrogen uptake. Surprisingly this is followed by a positive correlation with oxygen content contributing up to ∼0.6 wt% additional hydrogen uptake contradicting the conclusions of previous studies. Finally pore volume has the smallest effect. The pore size distribution is also found to be important since ultramicropores (dp < 0.7 nm) are found to be more positively correlated with excess uptake than micropores (dp < 2 nm). However this effect is quite small compared to the role of BET surface area and total pore volume. The novel approach taken here can provide important insights in the rational design of carbon materials for hydrogen storage applications.
Energy-Efficient Distributed Carbon Capture in Hydrogen Production from Natural Gas
Apr 2011
Publication
Lowering the energy penalty associated with CO2 capture is one of the key issues of Carbon Capture and Storage (CCS) technologies. The efficiency of carbon capture must be improved to reduce the energy penalty because capture stage is the most energy-consuming stage in the entire process of CCS. Energy-efficient distributed carbon capture in hydrogen production has been demonstrated with an advanced membrane reformer system. We have already developed and operated an advanced 40 Nm3 /h-class membrane reformer system and demonstrated its high hydrogen production efficiency of 81.4% (HHV) which is the world highest efficiency in terms of hydrogen production from natural gas. The system has another significant feature that the CO2 concentration in the reactor off-gas is as high as 70~90% and CO2 can be liquefied and separated easily with little energy loss. An apparatus for CO2 capture was combined to the membrane reformer system and over 90% of CO2 in the reactor off-gas was captured by cryogenic separation. The total energy efficiency of hydrogen production even with CO2 capture was still as high as 78.6% (HHV) which is 510% higher than the conventional reforming technologies. The total CO2 emission from hydrogen production was decreased by 50% with only a 3% energy loss. A sensitivity analysis was also carried out to evaluate the effects of the operating conditions of the system on hydrogen production efficiency and CO2 reduction rate.
How Knowledge about or Experience with Hydrogen Fueling Stations Improves Their Public Acceptance
Nov 2019
Publication
Hydrogen which is expected to be a popular type of next-generation energy is drawing attention as a fuel option for the formation of a low-carbon society. Because hydrogen energy is different in nature from existing energy technologies it is necessary to promote sufficient social recognition and acceptability of the technology for its widespread use. In this study we focused on the effect of initiatives to improve awareness of hydrogen energy technology thereby investigating the acceptability of hydrogen energy to those participating in either several hydrogen energy technology introduction events or professional seminars. According to the survey results participants in the technology introduction events tended to have lower levels of hydrogen and hydrogen energy technology knowledge than did participants in the hydrogen-energy-related seminars but confidence in the technology and acceptability of the installation of hydrogen stations near their own residences tended to be higher. It was suggested that knowledge about hydrogen and technology could lead to improved acceptability through improved levels of trust in the technology. On the other hand social benefits such as those for the environment socioeconomics and energy security have little impact on individual levels of acceptance of new technology.
The Potential Role of Flying Vehicles in Progressing the Energy Transition
Oct 2022
Publication
An energy transition is in progress around the globe notably led by an increase in the deployment of renewable energy and a shift toward less emissions-intense options notably in the transportation sector. This research investigates the potential role that new transportation options namely flying vehicles may play toward progressing the energy transition. As flying vehicles are a relatively new technology yet to penetrate the market it is also prudent to consider the ethical legal and social issues (ELSI) associated with their implementation alongside the potential energy and environmental impacts. Through a review of ELSI and energy and environmental literature we identify research gaps and identify how flying vehicles may impact upon the energy transition over time. Our research identifies several critical aspects of both ELSI and energy and environmental academia relevant to the future deployment of flying vehicles and describes a deployment timeline and the resultant societal outcomes. We find that flying vehicles could drive the energy transition and the hydrogen economy and that their widespread adoption could engender shared socio-environmental benefits. Our findings are relevant to transportation and environmental policymakers and identify critical considerations for the planned introduction of new shared transportation options to the market conducive to a sustainable energy transition.
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.
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.
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