Japan

The effect of carbon monoxide (CO) on the performance of polymer electrolyte fuel cells (PEFCs) with either a hydrogen circulation system or a hydrogen one-way pass system is investigated and compared. The voltage drop induced by adding 0.2 ppm of CO to the PEFC with the hydrogen circulation system was less than one-tenth of that observed in the PEFC with the hydrogen one-way pass system at 1000 mA cm–2 and a cell temperature of 60 °C. Gas analysis results showed that CO concentration in the hydrogen circulation system was lower than the initially supplied CO concentration. In the hydrogen circulation system permeated oxygen from the cathode should enhance CO oxidation. This should lead to decrease the CO concentration and mitigate the voltage drop in the hydrogen circulation system.

The power generation mix of the Association of Southeast Asian Nations (ASEAN) is dominated by fossil fuels which accounted for almost 80% in 2017 and are expected to account for 82% in 2050 if the region does not transition to cleaner energy systems. Solar and wind power are the most abundant energy resources but contribute negligibly to the power mix. Investors in solar or wind farms face high risks from electricity curtailment if surplus electricity is not used. Employing the policy scenario analysis of the energy outlook modelling results this paper examines the potential scalability of renewable hydrogen production from curtailed electricity in scenarios of high share of variable renewable energy in the power generation mix. The study found that ASEAN has high potential in developing renewable hydrogen production from curtailed electricity. The study further found that the falling cost of renewable hydrogen production could be a game changer to upscaling the large-scale hydrogen production in ASEAN through policy support. The results implied a future role of renewable hydrogen in energy transition to decarbonize ASEAN’s emissions.

Solar thermal technology can provide the United Arab Emirates and the Middle East region with abundant clean electricity to mitigate the rising levels of carbon dioxide and satisfy future demand. Hydrogen can play a key role in the large-scale application of solar thermal technologies such as concentrated solar plants in the region by storing the surplus electricity and exporting it to needed countries for profit placing the Middle East and the United Arab Emirates as major future green hydrogen suppliers. However a hydrogen supply chain comparison between hydrogen from CSP and other renewable under the UAE’s technical and economic conditions for hydrogen export is yet to be fully considered. Therefore in this study we provide a techno-economic analysis for well-to-ship solar hydrogen supply chain that compares CSP and PV technologies with a solid oxide water electrolyzer for hydrogen production assuming four different hydrogen delivery pathways based on the location of electrolyzer and source of electricity assuming the SOEC can be coupled to the CSP plant when placed at the same site or provided with electric heaters when placed at PV plant site or port sites. The results show that the PV plant achieves a lower levelized cost of electricity than that of the CSP plant with 5.08 ¢/kWh and 8.6 ¢/kWh respectively. Hydrogen production results show that the scenario where SOEC is coupled to the CSP plant is the most competitive scenario as it achieves the payback period in the shortest period compared to the other scenarios and also provides higher revenues and a cheaper LCOH of 7.85 $/kgH2.

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.

Hydrogen as an energy source has been identified as an optimal pathway for mitigating climate change by combining renewable electricity with water electrolysis systems. Proton exchange membrane (PEM) technology has received a substantial amount of attention because of its ability to efficiently produce high-purity hydrogen while minimising challenges associated with handling and maintenance. Another hydrogen generation technology alkaline water electrolysis (AWE) has been widely used in commercial hydrogen production applications. Anion exchange membrane (AEM) technology can produce hydrogen at relatively low costs because the noble metal catalysts used in PEM and AWE systems are replaced with conventional low-cost electrocatalysts. Solid oxide electrolyzer cell (SOEC) technology is another electrolysis technology for producing hydrogen at relatively high conversion efficiencies low cost and with low associated emissions. However the operating temperatures of SOECs are high which necessitates long startup times. This review addresses the current state of technologies capable of using impure water in water electrolysis systems. Commercially available water electrolysis systems were extensively discussed and compared. The technical barriers of hydrogen production by PEM and AEM were also investigated. Furthermore commercial PEM stack electrolyzer performance was evaluated using artificial river water (soft water). An integrated system approach was recommended for meeting the power and pure water demands using reversible seawater by combining renewable electricity water electrolysis and fuel cells. AEM performance was considered to be low requiring further developments to enhance the membrane’s lifetime.

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.

Building  the  international  hydrogen  supply  chain  requires  the  large-scale  liquefied   hydrogen(LH2) carrier. During shipping LH2 with LH2 Carrier the tank is pressurized by LH2 evaporation due to heat ingress from outside. Before unloading LH2 at the receiving terminal reducing the tank pressure is essential for the safe tank operation. However pressure reduction might cause flashing leading to rapid  vaporization  of liquefied  hydrogen  liquid  leakage.   Moreover  it  was  considered  that  pressure recovery phenomenon which was not preferred in terms of tank pressure management occurred at the beginning  of  pressure  reduction.  Hence  the   purpose  of  our  research  is  to  clarify  the phenomenon inside  the  cargo  tank  during   pressure  reduction.  The  CFD  analysis  of  the  pressure  reduction phenomenon was conducted with the   VOF based in-house CFD code utilizing the C-CUP scheme combined  with  the  hybrid   Level  Set  and  MARS  method.  In  our  previous  research  the  pressure reduction  experiments   with  the  30  m³  LH2  tank  were  simulated  and  the  results  showed  that  the pressure   recovery  was  caused  by  the  boiling  delay  and  the  tank  pressure  followed  the   saturation pressure  after  the  liquid  was  fully  stirred.  In  this  paper  the  results  were re-evaluated  in  terms  of temperature.  While  pressure  reduction  was  dominant  the  temperature  of  vapor-liquid  interface decreased.  Once  the  boiling  bubble  stirred  the  interface  its  temperature  reached  the  saturation temperature  after  pressure  recovery  occurred.  Moreover  it  was  found  that  the  liquid  temperature during  pressure  reduction  could  not  be  measured  because  of  the  boiling  from  the  wall  of  the thermometer. The CFD analysis on pressure reduction of 1250 m³ tank for the LH2 Carrier was also very could occur in the case of the 1250 m³ tank in a certain condition. These results provide new insight into the development of the LH2 carrier.

The dissemination of fuel-cell vehicles requires cost reduction of hydrogen refueling stations. The temperature of the supplied hydrogen has currently been cooled to approximately 40 C. This has led to larger equipment and increased electric power consumption. This study achieves a relaxation of the precooling temperature to the 20 C level while maintaining the refueling time. (1) Adoption of an MC formula that can flexibly change the refueling rate according to the precooling temperature. (2) Measurement of thermal capacity of refueling system parts and re-evaluation. Selection from multiple refueling control maps according to the dispenser design (Mathison et al. 2015). (3) Calculation of the effective thermal capacity and reselection of the map in real time when the line is cooled from refueling of the previous vehicle (Mathison and Handa 2015). (4) Addition of maps in which the minimum assumed pressures are 10 and 15 MPa. The new method is named MC Multi Map

Next-generation LH2 carriers may use the boil-off gas from the cargo tanks as additional fuel for the engine. As a consequence hydrogen pipes will enter the room of the ship’s propulsion system and transport hydrogen to the main engine. The hydrogen distribution resulting from a postulated hydrogen leak inside the room of the propulsion system has been analyzed by means of Computational Fluid Dynamics (CFD). In a subsequent step simulations with passive auto-catalytic recombiners (PARs) were carried out in order to investigate if the recombiners can increase the safety margins during such accident scenarios. CFD enables a 3D prediction of the transient distribution with a high resolution allowing to identify local accumulation of hydrogen and consequently to identify optimal PAR positions as well as to demonstrate the efficiency of the PARs. The simulation of the unmitigated reference case reveals a strong natural circulation driven by the density difference of hydrogen and the incoming cold air from the ventilation system. Globally this natural circulation dilutes the hydrogen and removes a considerable amount from the room of the ship’s propulsion system via the ventilation ducts. However a hydrogen accumulation beyond the flammability limit is identified below the first ceiling above the leak position and the back-side wall of the engine room. Based on these findings suitable positions for recombiners were identified. The design objectives of the PAR system were on the one hand to provide both high instantaneous and integral removal rate and on the other hand to limit build-up of flammable clouds by means of depletion and PAR induced mixing processes. The simulations performed with three different PAR arrangements (variation of large and<br/>small PAR units at different positions) confirm that the PARs reduce efficiently the hydrogen<br/>accumulations.

A fuel cell vehicle has a purging system for exhausting contaminated hydrogen gas. Notwithstanding the allowable hydrogen emissions levels in the purging system are regulated by the GTR a further research on the safety requirement of emissions concentrations is therefore needed for the vehicle design into a more rational system. In the present study the effects of flow speed concentration humidity on ignition characteristics of hydrogen/air mixtures were experimentally investigated. The results demonstrate that the value of Lower Flammable Limit increased with an increase in the velocity of hydrogen/air mixtures and slightly increased with a decrease in oxygen concentration.

Hydrogen has a high risk of ignition owing to its extremely low ignition energy and wide range of flammability. Therefore acquiring parameters relating to safe usage is of particular interest. The ignition of hydrogen generates combustion processes such as detonation and deflagration which may produce a blast wave. The severity of injuries sustained from a blast wave is determined by its strength. To reduce the physical hazards caused by explosion there is a need for some concepts for attenuating explosions and blast waves. In the present study we used water droplets as a material to reduce the blast wave strength. Numerical analysis of the interaction between blast waves and water droplets in a shock tube was conducted to understand the mitigation mechanism of blast wave. In this report we numerically modelled the experiment conducted by Mataradze et al. [1] to understand the main factor of blast mitigation by water droplets. In order to quantitatively clarify the mitigation effect of water droplets on the blast wave especially by quasi-steady drag here we conducted parameter studies on water droplet sprayed region. From this calculation it was suggested that the location of water droplet sprayed layer did not affect the blast mitigation effect at far side of the high explosives.

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.

Ensuring the energy transition in order to decrease CO2 and volatile organic compounds emissions and improve the efficiency of energy processes requires the development of advanced materials and technologies for the electrical energy sector. The article reviews superconducting materials functional nanomaterials used in the power industry mainly due to their magnetic electrical optical and dielectric properties and the thin layers of amorphous carbon nitride which properties make them an important material from the point of view of environmental protection optoelectronic photovoltaic and energy storage. The superconductivity-based technologies material processing and thermal and nonthermal plasma generation have been reviewed as technologies that can be a solution to chosen problems in the electrical energy sector and environment. The study explains directly both—the basics and application potential of low and high-temperature superconductors as well as peculiarities of the related manufacturing technologies for Roebel cables 1G and 2G HTS tapes and superconductor coil systems. Among the superconducting materials particular attention was paid to the magnesium di-boride MgB2 and its potential applications in the power industry. The benefits of the use of carbon films with amorphous structures in electronics sensing technologies solar cells FETs and memory devices were discussed. The article provides the information about most interesting from the R&D point of view groups of materials for PV applications. It summarises the advantages and disadvantages of their use regarding commercial requirements such as efficiency lifetime light absorption impact on the environment costs of production and weather dependency. Silicon processing inkjet printing vacuum deposition and evaporation technologies that allow obtaining improved and strengthened materials for solar cell manufacturing are also described. In the case of the widely developed plasma generation field waste-to-hydrogen technology including both thermal and non-thermal plasma techniques has been discussed. The review aims to draw attention to the problems faced by the modern power industry and to encourage research in this area because many of these problems can only be solved within the framework of interdisciplinary and international cooperation.

Fossil fuels and materials on Earth are a finite resource and the disposal of waste into the air on land and into water has an impact on our environment on a global level. Using Switzerland as an example the energy demand and the technical challenges and the economic feasibility of a transition to an energy economy based entirely on renewable energy were analyzed. Three approaches for the complete substitution of fossil fuels with renewable energy from photovoltaics called energy systems (ES) were considered i.e. a purely electric system with battery storage (ELC) hydrogen (HYS) and synthetic hydrocarbons (HCR). ELC is the most energy efficient solution; however it requires seasonal electricity storage to meet year-round energy needs. Meeting this need through batteries has a significant capital cost and is not feasible at current rates of battery production and expanding pumped hydropower to the extent necessary will have a big impact on the environment. The HYS allows underground hydrogen storage to balance seasonal demand but requires building of a hydrogen infrastructure and applications working with hydrogen. Finally the HCR requires the largest photovoltaic (PV) field but the infrastructure and the applications already exist. The model for Switzerland can be applied to other countries adapting the solar irradiation the energy demand and the storage options.

Fossil fuel consumption has triggered worries about energy security and climate change; this has promoted hydrogen as a viable option to aid in decarbonizing global energy systems. Hydrogen could substitute for fossil fuels in the future due to the economic political and environmental concerns related to energy production using fossil fuels. However currently the majority of hydrogen is produced using fossil fuels particularly natural gas which is not a renewable source of energy. It is therefore crucial to increase the efforts to produce hydrogen from renewable sources rather from the existing fossil-based approaches. Thus this study investigates how renewable energy can accelerate the production of hydrogen fuel in the future under three hydrogen economy-related energy regimes including nuclear restrictions hydrogen and city gas blending and in the scenarios which consider the geographic distribution of carbon reduction targets. A random effects regression model has been utilized employing panel data from a global energy system which optimizes for cost and carbon targets. The results of this study demonstrate that an increase in renewable energy sources has the potential to significantly accelerate the growth of future hydrogen production under all the considered policy regimes. The policy implications of this paper suggest that promoting renewable energy investments in line with a fairer allocation of carbon reduction efforts will help to ensure a future hydrogen economy which engenders a sustainable low carbon society.

Hydrogen is a low or zero-carbon energy source that is considered the most promising and potential energy carrier of the future. In this study the energy sources feedstocks and various methods of hydrogen production from power generation are comparatively investigated in detail. In addition this study presents an economic assessment to evaluate cost-effectiveness based on different economic indicators including sensitivity analysis and uncertainty analysis. Proton exchange membrane fuel cell (PEMFCs) technology has the most potential to be developed compared to several other technologies. PEMFCs have been widely used in various fields and have advantages (i.e. start-up zero-emissions high power density). Among the various sources of uncertainty in the sensitivity analysis the cost estimation method shows inflationary deviations from the proposed cost of capital. This is due to the selection process and untested technology. In addition the cost of electricity and raw materials as the main factors that are unpredictable.

The impact of ship emission reductions can be maximised by considering climate health and environmental effects simultaneously and using solutions fitting into existing marine engines and infrastructure. Several options available enable selecting optimum solutions for different ships routes and regions. Carbon-neutral fuels including low-carbon and carbon-negative fuels from biogenic or non-biogenic origin (biomass waste renewable hydrogen) could resemble current marine fuels (diesel-type methane and methanol). The carbon-neutrality of fuels depends on their Well-to-Wake (WtW) emissions of greenhouse gases (GHG) including carbon dioxide (CO2) methane (CH4) and nitrous oxide emissions (N2O). Additionally non-gaseous black carbon (BC) emissions have high global warming potential (GWP). Exhaust emissions which are harmful to health or the environment need to be equally removed using emission control achieved by fuel engine or exhaust aftertreatment technologies. Harmful emission species include nitrogen oxides (NOx) sulphur oxides (SOx) ammonia (NH3) formaldehyde particle mass (PM) and number emissions (PN). Particles may carry polyaromatic hydrocarbons (PAHs) and heavy metals which cause serious adverse health issues. Carbon-neutral fuels are typically sulphur-free enabling negligible SOx emissions and efficient exhaust aftertreatment technologies such as particle filtration. The combinations of carbon-neutral drop-in fuels and efficient emission control technologies would enable (near-)zero-emission shipping and these could be adaptable in the short- to mid-term. Substantial savings in external costs on society caused by ship emissions give arguments for regulations policies and investments needed to support this development.

The development of renewable energy technologies is essential to achieve carbon neutrality. Hydrogen can be stably stored and transported in large quantities to maximize power utilization. Detailed understanding of the characteristics and operating methods of water electrolysis technologies in which naturally intermittent fluctuating power is used directly is required for green hydrogen production because fluctuating power-driven water electrolysis processes significantly differ from industrial water electrolysis processes driven by steady grid power. Thus it is necessary to overcome several issues related to the direct use of fluctuating power. This article reviews the characteristics of fluctuating power and its generation as well as the current status and issues related to the operation conditions water electrolyzer configuration system requirements stack/catalyst durability and degradation mechanisms under the direct use of fluctuating power sources. It also provides an accelerated degradation test protocol method for fair catalyst performance comparison and share of effective design directions. Finally it discusses potential challenges and recommendations for further improvements in water electrolyzer components and systems suitable for practical use suggesting that a breakthrough could be realized toward the achievement of a sustainable hydrogen-based society.

Hydrogen is a versatile energy carrier which can be produced from variety of feedstocks stored and transported in various forms for multi-functional end-uses in transportation energy and manufacturing sectors. Several regional national and supra-national climate policy frameworks emphasize the need value and importance of Fuel cell and Hydrogen (FCH) technologies for deep and sector-wide decarbonization. Despite these multi-faceted advantages familiar and proven FCH technologies such as alkaline electrolysis and proton-exchange membrane fuel cell (PEMFC) often face economic technical and societal barriers to mass-market adoption. There is no single unified standardized and globally harmonized normative definition of costs. Nevertheless the discussion and debates surrounding plausible candidates and/or constituents integral for assessing the economics and value proposition of status-quo as well as developmental FCH technologies are steadily increasing—Life Cycle Costing (LCC) being one of them if not the most important outcome of such exercises.<br/>To that end this review article seeks to improve our collective understanding of LCC of FCH technologies by scrutinizing close to a few hundred publications drawn from representative databases—SCOPUS and Web of Science encompassing several tens of technologies for production and select transportation storage and end-user utilization cases. This comprehensive review forms part of and serves as the basis for the Clean Hydrogen Partnership funded SH2E project whose ultimate goal is the methodical development a formal set of principles and guardrails for evaluating the economic environmental and social impacts of FCH technologies. Additionally the SH2E projects will also facilitate the proper comparison of different FCH technologies whilst reconciling range of technologies methodologies modelling assumptions and parameterization found in existing literature.

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.

Renewable energy (solar and wind) sources have evolved dramatically in recent years around the globe primarily because they have the potential to generate environmentally friendly energy. However operating systems with high renewable energy penetration remain challenging due to the stochastic nature of these energy sources. To tackle these problems the authors propose a state machine-based energy management strategy combined with a hysteresis band control strategy for renewable energy hybrid microgrids that integrates hydrogen storage systems. By considering the power difference between the renewable energy source and the demand the battery’s state of charge and the hydrogen storage level the proposed energy management strategy can control the power of fuel cells electrolyzers and batteries in a microgrid and the power imported into/exported from the main grid. The results showed that the energy management strategy provides the following advantages: (1) the power supply and demand balance in the microgrid was balanced (2) the lifespans of the electrolyzer and fuel cell were extended and (3) the state of charge of the battery and the stored level of the hydrogen were appropriately ensured.

The combination of methane steam reforming technology and CCS (Carbon Capture and Storage) technology has great potential to reduce carbon emissions in the process of hydrogen production. Different from the traditional idea of capturing CO2 (Carbon Dioxide) in the exhaust gas with high work consumption this study simultaneously focuses on CO2 separation from fuel gas and recycling. A new hydrogen production system is developed by methane steam reforming coupled with carbon capture. Separated and captured high-purity carbon dioxide could be recycled for methane dry reforming; on this basis a new methane-dry-reforming-driven hydrogen production system with a carbon dioxide reinjection unit is innovatively proposed. In this study the energy flow and irreversible loss in the two newly developed systems are analyzed in detail through energy and exergy balance analysis. The advantages are explored from the perspective of hydrogen production rate natural gas consumption and work consumption. In addition in consideration of the integrated performance an optimal design analysis was conducted. In terms of hydrogen production the new system based on dry reforming is better with an advantage of 2.41%; however it is worth noting that the comprehensive thermal performance of the new steam reforming system is better reaching 10.95%. This study provides new ideas for hydrogen production from a low carbon emission perspective and also offers a new direction for future distributed energy system integration.

One of the significant safety concerns in large-scale storage and transportation of liquefied (cryogenic) hydrogen (LH2) is the formation of flammable hydrogen/air mixtures after leakages during storage or transportation. Especially in maritime transportation hydrogen accumulations could occur within large and congested geometries. The installation of passive auto-catalytic recombiners (PARs) is a suitable mitigation measure for local areas where venting is insufficient or even impossible. Numerical models describing the operational behavior of PARs are required to allow for optimizing the location and assessing the efficiency of the mitigation measure. In the present study the operational behavior of a PAR with a compact design has been experimentally investigated. In order to obtain data for model validation an experimental program has been performed in the REKO-4 facility a 5.5 m³ vessel. The test procedure includes two phases steady-state and dynamic. The results provide insights into the hydrogen recombination rates and catalyst temperatures under different boundary conditions.

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.

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.