Korea, Republic of

A large number of natural gas vehicles (NGV) with composite cylinders run in the world. In order to store hydrogen using the composite cylinder has also reached commercialization for the hydrogen fuel cell vehicle (FCV) which is been developing on ECO Energy. Under these increasing circumstances the most important issue is that makes sure of safety of the hydrogen composite cylinder. In case of the composite cylinder a standards to verify the safety of cylinders obey several country's standards. For NGV ISO 11439 has adopted as international standards but for FCV it has been still developing and there is only ISO/TS 15869 as international technical standards. In contents of international standards the fire test is the weakest part. The fire test is that the pressure relief valves (PRD) normally operate or not in order to prevent cylinders bursting when a vehicle is covered by fire. However with present standards there is no method to check the problem from vehicles in local flame. This study includes fire test results that have been performed to establish the fire-test standards.

NaBH4-based hydrogen generator for fuel cell Unmanned Aerial Vehicle (UAVs) with movable fuel cartridge was developed in the present study. The main fuel of hydrogen generator is Sodium borohydride (NaBH4) that is a kind of chemical hydride and has a high hydrogen storage density. In the previous studies hydrogen generators were developed in which hydrogen was directly generated from solid state NaBH4. However it was a prototype so inconvenient to replace the fuel after used up and lacked user convenience. Therefore the performance evaluation and the development procedure of NaBH4-based hydrogen generator that was designed taking user convenience in consideration for commercialization were described in this paper.

In this study the spread of cryogenic liquid due to a limited period of release is investigated for the first time to clarify the unclear conventional concept regarding two release types continuous and instantaneous release. In describing instantaneous release a discharge time has been assumed to be infinitesimally small; however such an assumption is unreal because there exists a finite period of release no matter how rapid it is. If the discharge time is less than the entire time domain the instantaneous release model should be added to the continuous model from the end of the time. This combined release that consists of the initial continuous model and subsequent instantaneous model is more realistic than the instantaneous release. The physical phenomenon is governed by three parameters: the evaporation rate per unit area release time and spill quantity. Third-order perturbation solutions are obtained and compared with a numerical solution to verify the perturbation solution. For the same spill quantity the combined model that consists of continuous and subsequent instantaneous model is necessary for small release times whereas the continuous model is only required for large release times. Additionally the combined release model is necessary for a small spill quantity at a fixed release time. These two release models are clearly distinguished using the perturbation solution.

A prospective global market share of Electric vehicle (EV) Hybrid electric vehicle (HEV) and Hydrogen Fuel Cell Vehicle (HFCV) is expected to grow due to stringent emission regulation and oil depletion. However it is essential to secure protection against high-pressure hydrogen gas and high-voltage in fuel cell vehicles and thus needs to develop a technique for safety assessment of HFCV. In this experiment 8 research institutes including the Korea Automobile Testing and Research Institute Hyundai Motor Company took part in. This project was supported by the Ministry of Land Transportation and Maritime Affairs of the Republic of Korea.

Because of the increasing challenges raised by climate change power generation from renewable energy sources is steadily increasing to reduce greenhouse gas emissions especially CO2 . However this has escalated concerns about the instability of the power grid and surplus power generated because of the intermittent power output of renewable energy. To resolve these issues this study investigates two technical options that integrate a power-to-gas (PtG) process using surplus wind power and the gas turbine combined cycle (GTCC). In the first option hydrogen produced using a power-to-hydrogen (PtH) process is directly used as fuel for the GTCC. In the second hydrogen from the PtH process is converted into synthetic natural gas by capturing carbon dioxide from the GTCC exhaust which is used as fuel for the GTCC. An annual operational analysis of a 420-MWclass GTCC was conducted which shows that the CO2 emissions of the GTCC-PtH and GTCC-PtM plants could be reduced by 95.5% and 89.7% respectively in comparison to a conventional GTCC plant. An economic analysis was performed to evaluate the economic feasibility of the two plants using the projected cost data for the year 2030 which showed that the GTCC-PtH would be a more viable option.

Hydrogen used in hydrogen fuel cell vehicles is the flammable gas which has wide flammable range and flame propagation speed is very fast. This fuel cell vehicle equipped with high-pressure vessel in the form of fuel to supply the high pressure hydrogen storage system needs to be checked carefully about a special safety design and exact weak point for high pressure repeated fatigue. 70 L liner and 70 MPa Type-3 vessel were tested using the equipments which can perform ambient hydraulic cycling test and burst test in the Korea Gas Safety Corporation. And it was performed to identify the internal external behaviour through the Finite Element Analysis (FEA) and real leakage mode for high pressure repeated fatigue when subjected to be pressurized in vessel. 70 L liner and 70 MPa Type-3 vessel were tested using the equipments which can perform ambient hydraulic cycling test and burst test in the Korea Gas Safety Corporation. And it was performed to identify the internal external behaviour through the Finite Element Analysis (FEA) and real leakage mode for high pressure repeated fatigue when subjected to be pressurized in vessel. Through this study liner of type-3 hydrogen vessel is ruptured first on cylindrical (body) part than Dome part in 8.5 MPa. Also the same Phenomena are confirmed through the Finite Element Analysis (FEA). External composite leakage mode in ambient hydraulic cycling test was occurred in different area such as the Dome Dome knuckle and cylindrical (body) parts. But cracks of inner liner for gas tight were occurred in only cylindrical (body) parts. Also in FEA results when vessel is pressurized Dome knuckle and cylindrical (body) parts is weakest among all parts because of expansion of cylindrical (body) parts.

Hydrogen is being considered as a pathway to decarbonize large energy systems and for utility-scale energy storage. As these applications grow transportation infrastructure that can accommodate large quantities of hydrogen will be needed. Many millions of tons of hydrogen are already consumed annually some of which is transported in dedicated hydrogen pipelines. The materials and operation of these hydrogen pipeline systems however are managed with more constraints than a conventional natural gas pipeline. Transitional strategies for deep decarbonization of energy systems include blending hydrogen into existing natural gas systems where the materials and operations may not have the same controls. This study explores the hydrogen compatibility of existing pipeline steels and the suitability of these steels in hydrogen pipeline systems. Representative fracture and fatigue properties of pipeline grade steels in gaseous hydrogen are summarized from the literature. These properties are then considered in idealized design life calculations to inform materials performance for a typical gas pipeline.

High-order perturbation solutions have been obtained for the simple physical model describing the LH2 spreading with a continuous spill and are shown to improve over the first-order perturbation solutions. The non-dimensional governing equations for the model are derived to obtain more general solutions. Non-dimensional parameters are sought as the governing parameters for the non-dimensional equations and the non-dimensional evaporation rate is used as the perturbation parameter. The results show that the second-order solutions exhibit an improvement over the first-order solutions with respect to the pool volume; however there is still a difference between numerical solutions and second-order solutions in the late stage of spread. Finally it is revealed that the third-order solutions almost agree with numerical solutions.

The rise in hydrogen fuel cell electric vehicles (FCEVs) is expected to pose a variety of hazards on the road. Vehicles using hydrogen could cause significant damage owing to hydrogen vapor cloud explosions jet fires caused by leakage or hydrogen tank explosions. This risk is expected to further increase in semi-enclosed spaces such as underground parking lots and road tunnels. Therefore it is necessary to study the fire safety of hydrogen vehicles in semi-enclosed spaces. In this study an experiment on hydrogen tank explosion was performed. In addition the CFD numerical model was verified using the experimental results and the damaging effect due to pressure propagation during hydrogen tank explosions in underground parking lots and road tunnels was analyzed using numerical analysis. From the experiment results the hydrogen tank exploded at about 80 Mpa a maximum incident pressure is generated 267 kPa at a distance of 1.9 m. As a result of numerical analysis based on the experimental results the limit distance that can cause serious injury due to the explosion of a hydrogen tank in a road tunnel or underground parking lot was analyzed up to about 20 m from the point of explosion.

We performed a hydrogen combustion analysis in the Advanced Power Reactor 1400 MWe (APR1400) containment during a severe accident initiated by a small break loss of coolant accident (SBLOCA) which occurred at a lower part of the cold leg using a multi-dimensional hydrogen analysis system (MHAS) to confirm the integrity of the APR1400 containment. The MHAS was developed by combining MAAP GASFLOW and COM3D to simulate hydrogen release distribution and combustion in the containment of a nuclear power plant during the severe accidents in the containment of a nuclear power reactor. The calculated peak pressure due to the flame acceleration by the COM3D using the GASFLOW results as an initial condition of the hydrogen distribution was approximately 555 kPa which is lower than the fracture pressure 1223 kPa of the APR1400 containment. To induce a higher peak pressure resulted from a strong flame acceleration in the containment we intentionally assumed several things in developing an accident scenario of the SBLOCA. Therefore we may judge that the integrity of the APR1400 containment can be maintained even though the hydrogen combustion occurs during the severe accident initiated by the SBLOCA.

The purpose of this research was to derive promising technologies for the transport of hydrogen fuel cells thereby supporting the development of research and development policy and presenting directions for investment. We also provide researchers with information about technology that will lead the technology field in the future. Hydrogen energy as the core of carbon neutral and green energy is a major issue in changing the future industrial structure and national competitive advantage. In this study we derived promising technology at the core of future hydrogen fuel cell transportation using the published US patent and paper databases (DB). We first performed text mining and data preprocessing and then discovered promising technologies through generative topographic mapping analysis. We analyzed both the patent DB and treatise DB in parallel and compared the results. As a result two promising technologies were derived from the patent DB analysis and five were derived from the paper DB analysis.

In this study ethylene glycol (EG) and terephthalic acid (TPA) were used to generate hydrogen using copper electrodes in an alkaline aqueous solution and the corresponding reaction mechanism was experimentally investigated. Both EG and TPA produced hydrogen; however TPA consumed OH− inhibiting the production of intermediary compounds of EG and causing EG to actively react with H2O ultimately leading to enhanced hydrogen production. In addition the initiation potential of water decomposition of the EG and TPA alkaline aqueous solution was 1.0 V; when 1.8 V (vs. RHE) was applied the hydrogen production reached 440 mmol L⁻¹ which was substantially greater than the hydrogen production rate of 150 mmol L⁻¹ during water decomposition.

This study proposed a strategy for selecting an optimal propulsion system of a liquefied hydrogen tanker. Four propulsion system options were conceivable depending on whether the hydrogen BOG (boil-off gas) from the cryogenic cargo tanks was used for fuel or not. These options were evaluated in terms of their economic technological and environmental feasibilities. The comparison scope included not only main machinery but also the BOG handling system with electric generators. Cost-benefit analysis life-cycle costing including carbon tax and an energy efficiency design index were used as measures to compare the four alternative systems. The analytic hierarchy process made scientific decision-making possible. This methodology provided the priority of each attribute through the use of pairwise comparison matrices. Consequently the propulsion system using LNG with hydrogen BOG recovery was determined to be the optimal alternative. This system was appropriate for the tanker that achieved the highest evaluation score.

A series of experiments were performed in the SPARC (spray-aerosol-recombiner-combustion) test facility to simulate a hydrogen mitigation system with the actuation of a PAR (passive auto-catalytic re-combiner) and spray system. In this study the SPARC-SPRAY-PAR (SSP1) experiment is chosen to benchmark the MELCOR (a lumped-parameter code for severe accident analysis) predictions against test data. For this purpose firstly we prepared the base input model of the SPARC test vessel and tested it by a simple verification problem with well-defined boundary conditions. The implementation of a currently used PAR correlation in MELCOR is shown to be appropriate for the simulation of a PAR actuation experiment. In an SSP1 experiment the PAR is reacting with hydrogen and the spray actuation starts as soon as hydrogen injection is complete. The MELCOR simulation well predicts the pressure behavior and the gas flow affected by operating both a PAR and spray system. However the local hydrogen concentration measurement near the inlet nozzle is much higher than the volume average-value by MELCOR since high jet flow from the nozzle is dispersed in the corresponding cell volume. The experimental reproduction of the phenomena we expect or conversely the identification of phenomena we do not understand will continue to support the verification of analytical models using experimental data and to analyze the impact of spray on PAR operations in severe accident conditions.

A critical drawback of battery-powered eVTOL UAVs is their limited range and endurance and this drawback could be solved by using a combination of hydrogen fuel cells and batteries. The objective of this paper is to develop a sizing methodology for the lift+cruise-type eVTOL UAV powered by a hydrogen fuel cell and battery. This paper presents the constraints analysis method for forward flight/VTOL multi-mode UAV the regression model for electric propulsion system sizing a sizing method for an electric propulsion system and hydrogen fuel cell system and a transition analysis method. The total mass of the UAV is iteratively calculated until convergence and the optimization method is used to ensure that the sizing results satisfy the design requirements. The sizing results are the UAV’s geometry mass and power data. To verify the accuracy of the proposed sizing methodology the sizing and the conceptual design phase results of a 25 kg hydrogen fuel-cell-powered UAV are compared. All parameters had an error within 10% and satisfied the design requirements.

We report volumetric analysis techniques to analyze the transport properties of hydrogen dissolved in cylindrical-shaped polymers. The techniques utilize the volume measurement of the released hydrogen from rubber by gas collection in a graduated cylinder after charging sample with high-pressure hydrogen and subsequent decompression. We further improve the graduated cylinder with some modifications such as reading the electrical capacitance of the water level using electrodes and changing the sample loading position. From the measurement results the uptake (C∞) diffusion coefficient (D) and solubility (S) of hydrogen are quantified with an upgraded diffusion analysis program. These methods are applied to three cylindrical rubbers. Dual adsorption behaviors with increasing pressure are observed for all the samples. C∞ follows Henry’s law up to ~15 MPa whereas Langmuir model applies up to 90 MPa. D shows Knudsen and bulk diffusion behavior below and above pressure respectively. A COMSOL simulation is compared with experimental observations.

Managing the concentration of atmospheric CO₂ requires a multifaceted engineering strategy which remains a highly challenging task. Reducing atmospheric CO₂ (CO2R) by converting it to value-added chemicals in a carbon neutral footprint manner must be the ultimate goal. The latest progress in CO2R through either abiotic (artificial catalysts) or biotic (natural enzymes) processes is reviewed herein. Abiotic CO2R can be conducted in the aqueous phase that usually leads to the formation of a mixture of CO formic acid and hydrogen. By contrast a wide spectrum of hydrocarbon species is often observed by abiotic CO2R in the gaseous phase. On the other hand biotic CO2R is often conducted in the aqueous phase and a wide spectrum of value-added chemicals are obtained. Key to the success of the abiotic process is understanding the surface chemistry of catalysts which significantly governs the reactivity and selectivity of CO2R. However in biotic CO2R operation conditions and reactor design are crucial to reaching a neutral carbon footprint. Future research needs to look toward neutral or even negative carbon footprint CO2R processes. Having a deep insight into the scientific and technological aspect of both abiotic and biotic CO2R would advance in designing efficient catalysts and microalgae farming systems. Integrating the abiotic and biotic CO2R such as microbial fuel cells further diversifies the spectrum of CO2R.

The depletion of fossil fuels and rising global warming challenges encourage to find safe and viable energy storage and delivery technologies. Hydrogen is a clean efficient energy carrier in various mobile fuel-cell applications and owned no adverse effects on the environment and human health. However hydrogen storage is considered a bottleneck problem for the progress of the hydrogen economy. Liquid-organic hydrogen carriers (LOHCs) are organic substances in liquid or semi-solid states that store hydrogen by catalytic hydrogenation and dehydrogenation processes over multiple cycles and may support a future hydrogen economy. Remarkably hydrogen storage in LOHC systems has attracted dramatically more attention than conventional storage systems such as high-pressure compression liquefaction and absorption/adsorption techniques. Potential LOHC media must provide fully reversible hydrogen storage via catalytic processes thermal stability low melting points favorable hydrogenation thermodynamics and kinetics large-scale availability and compatibility with current fuel energy infrastructure to practically employ these molecules in various applications. In this review we present various considerable aspects for the development of ideal LOHC systems. We highlight the recent progress of LOHC candidates and their catalytic approach as well as briefly discuss the theoretical insights for understanding the reaction mechanism.

This review study attempts to summarize available energy storage systems in order to accelerate the adoption of renewable energy. Inefficient energy storage systems have been shown to function as a deterrent to the implementation of sustainable development. It is therefore critical to conduct a thorough examination of existing and soon-to-be-developed energy storage technologies. Various scholarly publications in the fields of energy storage systems and renewable energy have been reviewed and summarized. Data and themes have been further highlighted with the use of appropriate figures and tables. Case studies and examples of major projects have also been researched to gain a better understanding of the energy storage technologies evaluated. An insightful analysis of present energy storage technologies and other possible innovations have been discovered with the use of suitable literature review and illustrations. This report also emphasizes the critical necessity for an efficient storage system if renewable energy is to be widely adopted.

This work deals with the numerical investigation of a three-dimensional laminar hydrogenair diffusion flame in which a cylindrical fuel jet is surrounded by in-flowing air. To calculate the distribution of gas molecules the model solves the species conservation equation for N-1 components using infinity fast chemistry and irreversible chemical reaction. The consideration of the component-specific diffusion has a strong influence on the position of the high-temperature zone as well as on the concentration distribution of the individual gas molecules. The calculations of the developed model predict the radial and axial species and temperature distribution in the combustion chamber comparable to those from previous publications. Deviations due to a changed burner geometry and air supply narrow the flame structure by up to 50% and the high-temperature zones merge toward the central axis. Due to the reduced inflow velocity of the hydrogen the high-temperature zones develop closer to the nozzle inlet of the combustion chamber. As the power increases the length of the cold hydrogen jet increases. Furthermore the results show that the axial profiles of temperature and mass fractions scale quantitatively with the power input by the fuel.

Visible-light-driven hydrogen production through photocatalysis has attracted enormous interest owing to its great potential to address energy and environmental issues. However photocatalysis possesses several limitations to overcome for practical applications such as low light absorption efficiency rapid charge recombination and poor stability of photocatalysts. Here the preparation of efficient noble metal–semiconductor hybrid photocatalysts for photocatalytic hydrogen production is presented. The prepared ternary Rh–TiO₂–CeO₂ hybrid photocatalysts exhibited excellent photocatalytic performance toward the hydrogen production reaction compared with their counterparts ascribed to the synergistic combination of Rh TiO₂ and CeO₂.

In June 2021 the United States (US) Department of Energy (DOE) hosted the first-ever Hydrogen Shot Summit which lasted for two days. More than 3000 stockholders around the world were convened at the summit to discuss how low-cost clean hydrogen production would be a huge step towards solving climate change. Hydrogen is a dynamic fuel that can be used across all industrial sectors to lower the carbon intensity. By 2030 the summit hopes to have developed a means to reduce the current cost of clean hydrogen by 80%; i.e. to USD 1 per kilogram. Because of the importance of clean hydrogen towards carbon neutrality the overall DOE budget for Fiscal Year 2021 is USD 35.4 billion and the total budget for DOE hydrogen activities in Fiscal Year 2021 is USD 285 million representing 0.81% of the total DOE budget for 2021. The DOE hydrogen budget of 2021 is estimated to increase to USD 400 million in Fiscal Year 2022. The global hydrogen market is growing and the US is playing an active role in ensuring its growth. Depending on the electricity source used the electrolysis of hydrogen can have no greenhouse gas emissions. When assessing the advantages and economic viability of hydrogen production by electrolysis it is important to take into account the source of the necessary electricity as well as emissions resulting from electricity generation. In this study to evaluate the levelized cost of nuclear hydrogen production the International Atomic Energy Agency Hydrogen Economic Evaluation Program is used to model four types of LWRs: Exelon’s Nine Mile Point Nuclear Power Plant (NPP) in New York; Palo Verde NPP in Arizona; Davis-Besse NPP in Ohio; and Prairie Island NPP in Minnesota. Each of these LWRs has a different method of hydrogen production. The results show that the total cost of hydrogen production for Exelon’s Nine Mile Point NPP Palo Verde NPP Davis-Besse NPP and Prairie Island NPP was 4.85 ± 0.66 4.77 ± 1.36 3.09 ± 1.19 and 0.69 ± 0.03 USD/kg respectively. These findings show that among the nuclear reactors the cost of nuclear hydrogen production using Exelon’s Nine Mile Point NPP reactor is the highest whereas the cost of nuclear hydrogen production using the Prairie Island NPP reactor is the lowest.

Leading countries are developing clean energy to replace fossil fuels. In this context Russia is changing its energy policy towards fostering new energy resources such as hydrogen and helium. Hydrogen will not only contribute to Russia’s financial revenue by replacing natural gas but will also provide a basis for it to maintain its dominance over the international energy market by pioneering new energy markets. Russia is aiming to produce more than two million tons of hydrogen fuel for export to Europe and Asia by 2035. However it is facing many challenges including developing hydrogen fuel storage systems acquiring the technology required for exporting hydrogen and building trust in the fuel market. Meanwhile South Korea has a foundation for developing a hydrogen industry as it has the highest capacity in the world to produce fuel cells and the ability to manufacture LNG: (liquefied natural gas) carriers. Therefore South Korea and Russia have sufficient potential to create a new complementary and reciprocal cooperation model in the hydrogen fuel field. This study examines the present and future of Russia’s energy policy in this area as well as discusses South Korea and Russia’s cooperation plans in the hydrogen fuel sector and the related implications.

Predicting lower flammability limits (LFL) of hydrogen has become an ever-important task for safety of nuclear industry. While numerous experimental studies have been conducted LFL results applicable for the harsh environment are still lack of information. Our aim is to develop a calculated non-adiabatic flame temperature (CNAFT) model to better predict LFL of hydrogen mixtures in nuclear power plant. The developed model is unique for incorporating radiative heat loss during flame propagation using the CNAFT coefficient derived through previous studies of flame propagation. Our new model is more consistent with the experimental results for various mixtures compared to the previous model which relied on calculated adiabatic flame temperature (CAFT) to predict the LFL without any consideration of heat loss. Limitation of the previous model could be explained clearly based on the CNAFT coefficient magnitude. The prediction accuracy for hydrogen mixtures at elevated initial temperatures and high helium content was improved substantially. The model reliability was confirmed for H2-air mixtures up to 300 C and H2-air-He mixtures up to 50 vol % helium concentration. Therefore the CNAFT model developed based on radiation heat loss is expected as the practical method for predicting LFL in hydrogen risk analysis.

Recently severe accidents in nuclear power plants (NPPs) have become a global concern. The aim of this paper is to predict the hydrogen buildup within containment resulting from severe accidents. The prediction was based on NPPs of an optimized power reactor 1000. The increase in the hydrogen concentration in severe accidents is one of the major factors that threaten the integrity of the containment. A method using a fuzzy neural network (FNN) was applied to predict the hydrogen concentration in the containment. The FNN model was developed and verified based on simulation data acquired by simulating MAAP4 code for optimized power reactor 1000. The FNN model is expected to assist operators to prevent a hydrogen explosion in severe accident situations and manage the accident properly because they are able to predict the changes in the trend of hydrogen concentration at the beginning of real accidents by using the developed FNN model.