There are efforts to switch from fossil energy to hydrogen energy around the world. In Korea, efforts are being made to move toward a hydrogen society by building hydrogen cities. Hydrogen cities are intended to use hydrogen energy for urban infrastructure, and hydrogen fuel cells are installed in residential buildings to provide heat and electricity. In this study, hazard and operability (HAZOP) which evaluates the risk of the process, and job safety analysis (JSA), which evaluates the risk of human error, were conducted for the integrated system of hydrogen extractor and fuel cell. The risk assessment is analyzed and a safety manual is prepared to ensure the safety of the integrated system.

Conventional well-to-wheel (WTW) analyses of battery electric vehicles (BEVs) typically present a single value for WTW greenhouse gas (GHG) emissions using the national average electricity mix for a specific year. However, the power generation mix used in WTW analyses of BEVs is time-dependent. This study focuses on analyzing the variability of WTW GHG emissions depending on the time of BEV charging. For this analysis, the Korean GREET model was used, which was modified from the GREET model developed by Argonne National Laboratory to reflect local conditions. The analysis shows that the highest WTW GHG emissions occur when fossil fuels make up around 70% of the power mix, while the lowest emissions occur when fossil fuels account for about 44% and renewable energy for around 10%. WTW GHG emissions of BEVs are 16% higher at their peak and 28% lower at their minimum compared to scenarios that do not consider the power mix.

Hydrogen is gaining attention as a clean energy alternative to fossil fuels. In Korea, hydrogen refueling stations (HRS) are continuously expanding as hydrogen mobility is commercialized, and it is expected to account for 33% of Korea's total energy consumption by 2050. Hydrogen is easily ignited with low ignition energy, and its wide flammability range and fast combustion rate can lead to fires/explosions after leakage, causing major accidents. In Korea, hydrogen is handled in a semi-enclosed space according to special cases, which is very dangerous due to hydrogen leakage, and explosion safety can be improved by removing the installation of explosion venting and ventilation. For this reason, we would like to study the safety management of packaging HRS, which are semi-enclosed spaces.

Hydrogen electric vehicles require dedicated components different from those needed for traditional internal combustion engines. In particular, the receptacle used for refueling the hydrogen tank operates under low temperatures and high pressures. Due to hydrogen's characteristics, experiments using it under actual operating conditions pose significant risks, necessitating alternative experiments with inert gases at room temperature and atmospheric pressure. This study conducted a numerical analysis of the internal flow within the receptacle to understand the relationship between results obtained using hydrogen and inert gases under identical conditions. Numerical analysis results were obtained using hydrogen and two inert gases under various pressure, velocity, and flow conditions, including actual operating conditions(700 bar, -40℃). The analysis revealed that the differential pressure of each gas is closely related to the dynamic pressure, enabling the prediction of hydrogen differential pressure using inert gases.

This study performed a continuous durability evaluation experiments on the proton exchange membrane (PEM) water electrolysis system. The dynamic characteristics of the system caused by the durability reduction was analyzed. A stack deterioration experiment was conducted by measuring the voltage change under a constant current conditions at the operating temperature. The water electrolysis stack durability data for long-term operation obtained through this study showed that performance decreased by about 18% during about 1,500 hours of operation. As a results, the durability of the stack rapidly decreased, and the power consumption of the stack increased on the dynamic simulation for PEM water electrolysis system.

In this study, explosion characteristics with varying initial pressure and equivalence ratio were identified under the conditions of α=43% (40% NH₃, 45% H₂, and 15% N₂), which are reported to be similar to the laminar flame properties of methane/air mixtures. The maximum explosion pressure (P_max) and explosion index (K_G) reached the maximum values at equivalence ratio of 1.1, while the explosion time (t_c) reached its minimum at 1.1. Furthermore, it was observed that as the initial pressure increased, both the explosion pressure and explosion time increased.

This paper describes the design and modeling processes for a testbed developed to evaluate the performance of helium compressors, essential components in a 5 TPD hydrogen liquefaction plant. The compressor operates under inlet of 7.0 bar and 293.1 K, and outlet of 25.9 bar and 315.1 K, and resulting in a specific energy consumption of 11.42 kWh/kgLH₂. The testbed is designed to supply gas, cooling water, and other utilities necessary for compressor operation. Furthermore, the testbed design was validated through static modeling using Aspen HYSYS, which included the compressor's performance curves, surge protection systems, stage-wise speeds, and detailed geometries of intercoolers and aftercoolers. The modeled calculations showed agreement within a 5% error compared to the testbed's design values.

In this study, an alkaline water electrolysis system was built and a hardware-in-the loop simulation (HILS) was developed that can simultaneously operate the experimental device and system simulator in real time to evaluate dynamic characteristics fault diagnosis by receiving data from the system. In order to analyze the dynamic characteristics, a numerical model was developed considering the temperature transient phenomenon according to the load of the stack. The alkaline water electrolysis simulations using various mathematical models agreed very well with experimental results. As a result, an abnormal conditions were detected in real time for system failure diagnosis using HILS.

This study analyzes one year of hydrogen sales data from an off-site hydrogen charging station in South Korea to identify factors influencing sales and develop a forecasting model using long short-term memory (LSTM) model. The LSTM model's performance was compared with the existing traditional time series models, seasonal auto-regressive integrated moving average (SARIMA) and SARIMA with exogenous factors (SARIMAX). Key factors such as the day of the week, holidays, and weather significantly impact sales, with comparatively higher sales observed on Fridays, weekends, holidays and clear days. The LSTM model outperformed SARIMA and SARIMAX, effectively capturing nonlinear relationships between sales and factors. In addition, the forecasting model proposed in this study showed improved performance compared to the forecasting model proposed in previous study. Despite some limitations, this research provides valuable insights for improving operational efficiency at hydrogen charging stations.

In this paper, the cleaning performance characteristics of the impeller in the debris filter for a heat exchanger cleaning system were investigated using response surface method (RSM) with commercial computational fluid dynamics (CFD) code. Design variables were defined with the controllable porous of debris filter shape. The objective function was defined as the differential pressure at inlet and outlet of debris filter. The design optimization of the design variables was determined using the RSM. The numerical results for the reference and optimum models were compared and discussed in this work.

To achieve carbon neutrality, many countries and companies around the world have adopted hydrogen energy as a key energy source for the future. Major countries such as Europe, China, the United States, and Japan are already conducting large-scale empirical research and commercialization to secure hydrogen production technology, a core technology of the hydrogen industry. Our government is pursuing large-scale R&D projects with related companies to secure water electrolysis technology, a core technology for the hydrogen industry. At present, for the development of domestic water electrolysis technology, it is important to increase the size of production facilities and ensure safety. In this study, we seek to discover the risk factors inherent in alkaline water electrolysis equipment and analyze the extent of damage that will occur in the event of an accident due to these risk factors. Therefore, we would like to raise awareness of the importance of ensuring the safety of water electrolysis equipment.

This study aims to evaluate the structural integrity of protective walls at hydrogen refueling stations during an explosion and to test their resistance to actual blast pressure. These protective walls are defined by the Korea Gas Safety Corporation (KGS) and play a crucial role in protecting surrounding areas and minimizing damage in the event of an explosion. The research involves constructing walls made of concrete blocks, steel plates, and reinforced concrete according to KGS specifications and validating their effectiveness through explosion tests. Through this, the study seeks to enhance the safety of hydrogen refueling stations and contribute to the expansion of infrastructure and the promotion of hydrogen vehicles, facilitating the transition to a hydrogen-based society.

In this study, a hazard and operability (HAZOP) risk assessment is conducted to identified potential risks and to improve safety level in the stage of design of a hydrogen fueled gas turbine combined cycle power plant which co-fire hydrogen with conventional fuel of natural gas. For the stable operation of a hydrogen fueled combined cycle power plant, it is crucial to identify the potential risks during the development of relevant technologies. By assessing risk factors in hydrogen supply system, improvement recommendations such as changes in the location and the number of piping accessories and facilities, as well as safety training, were proposed. The obtained results and lessons to reinforce the level of safety are expected to contribute to the safe use of hydrogen as a new decarbonized fuel for power generation.

The injection of hydrogen into urban gas pipelines has established itself as an important strategy for achieving carbon neutrality and facilitating energy transition. By utilizing existing infrastructure, it reduces economic burdens, and the successful experimental results from various countries serve as positive signals for the activation of the hydrogen economy. These international case studies will be crucial references for enhancing the safety and efficiency of hydrogen blending technologies in the future.

Fe-Pt/C nanocatalysts were prepared via spontaneous reduction reaction of nickel(II) acetylacetonate and platinum(II) acetylacetonate on the surface of carbon black in dry process, and their morphology and elemental analysis were characterized by scanning electron microscopy, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy. The loading weight of the nanocatalysts was measured by thermogravimetric analysis and the surface area was measured by BET analysis. TEM observation showed that Ni and Pt nanoparticles was well dispersed on the carbon black and their average particle size was 4.21 nm. The loading weight of Ni-Pt nanocatalysts on the carbon black was 5.96-6.83 wt%, and the value increased with increasing nickel(II) acetylacetonate content. As the Ni-Pt loading weight increased, the specific surface area decreased significantly by more than 70%, because Ni-Pt nanoparticles block the micropores of carbon black. I-V characteristics showed that water electrolysis performance increased with increasing Pt nanocatalyst content.

In order to increase the public acceptance of hydrogen in the process of expanding the supply of gaseous hydrogen and liquid hydrogen vehicle charging stations in accordance with the government's revitalization of the hydrogen economy policy, the safety of hydrogen vehicle charging stations has been strengthened through the introduction of a risk assessment system, unlike the existing liquefied petroleum gas or high-pressure gas charging stations. In this paper, a risk assessment was conducted for the newly introduced hydrogen vehicle charging station, and a comparative analysis was conducted between the results and the required legal safety distance. To this end, the node classification for the qualitative evaluation of hydrogen refueling stations was classified in the same way as the safety distance facility classification of the law, and the fire explosion caused by hydrogen leakage was separately classified among the scenarios according to the risk review results to conduct a quantitative risk assessment. As a result of quantitative risk evaluation, the personal risk level is 1.0×10^-7 (1/year) with a radius of 24 m, and the social risk is 1.5×10^-6 (1/year), which satisfies the acceptable criteria. As a result of the risk assessment of gaseous hydrogen and liquid hydrogen charging stations, it was confirmed that the legal safety distance of domestic hydrogen charging stations is longer than the results of safety distance and risk assessment in foreign countries, and it is judged that it is possible to scientifically discuss the safety distance of hydrogen vehicle charging stations on the premise that sufficient accident damage can be minimized through safety measures.