• Journal of Hydrogen and New Energy
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• v.33 no.2
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• pp.121-129
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• 2022

With the advent of the post-2020 climate regime, the hydrogen industry is growing rapidly around the world. In order to build the hydrogen economy, it is important to identify social issues related to hydrogen and prepare countermeasures for them. Accordingly, this study conducted a semantic network analysis on hydrogen news from NAVER. As a result of the analysis, the number of hydrogen news in 2020 increased by 4.5 times compared to 2016, and as of 2018, the hydrogen issue has shifted from an environmental aspect to an economic aspect. In addition, although the initial government-led hydrogen industry is expanding to the mobility field such as privately-led fuel cell electric vehicles and hydrogen fuel, terms showing concerns about the safety such as explosions are constantly being exposed. Thus, it is necessary not only to expand the hydrogen ecosystem through the participation of private companies, but also to promote hydrogen safety.

• Journal of Hydrogen and New Energy
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• v.34 no.5
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• pp.389-397
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• 2023

This study compares domestic and foreign research on renewable energy-based water electrolysis clean hydrogen. Domestic studies from 2010 to 2023 focused on technological efficiency, energy efficiency, and system efficiency, with few analyzing infrastructure and technology trends. Overseas research initially focused on technological efficiency and stability, but has since shifted to economic and environmental impact, policy effectiveness, industry-university-research cooperation, and sustainability. To improve water electrolysis technology production, this study suggests prioritizing technology stability over efficiency, resolving government regulations and resident acceptance issues, promoting industry-university-institute cooperation for rapid commercialization of research results, and developing a strategy for sustainable development of renewable energy-based water electrolysis technology.

• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.608-614
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• 2023

The fast filling process of high-pressure hydrogen has an important impact on the filling efficiency and safety. In this paper, a specific study is carried out on the thermophysical phenomena during the fast filling process. Starting from the gas state equation of hydrogen, the change law of the hydrogen storage temperature is obtained, and then the temperature rise prediction is constructed. The model can clarify the relationship between the filling parameters and the temperature rise during the fast filling process, thereby revealing the flow and heat transfer laws of the fast charging process. To improve the theoretical research basis for the evaluation of vehicle-mounted hydrogen fast charging capacity, temperature prediction and optimization of hydrogenation methods.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.407-413
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• 2006

Artificial aggregates made by coal fly ash that is classified as an industrial by-product was tested to oxidize hydrogen sulfide under various testing conditions. For the determination of optimum condition for converting coal fly ash to aggregates, specimens were prepared by varying ratio of fly ash, cement, water content, and foaming agent. These specimens were tested to determine specific gravity, water absorption, and compressive strength. Specimens, which were used for the removal of hydrogen sulfide, were selected based on the measured specific gravity, water absorption, and compressive strength. Tests for hydrogen sulfide removal were performed via batch and column tests. Under the testing conditions used in this study, removal rates of hydrogen sulfide were linearly proportional to amounts of coal fly ash, and further increased when water was added.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2010.04a
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• pp.192-192
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• 2010

현재 산업과 과학의 발달로 인한 무분별한 화석연료의 사용은 에너지자원의 고갈과 환경오염의 문제를 야기시켜, 이의 해결을 위한 청정 신에너지에 대한 연구가 전 세계적으로 집중되고 있다. 이 중 바이오매스는 화석연료보다 비교적 높은 H/C 비를 갖기 때문에 신에너지인 수소 또는 Syngas를 생산하기 위한 가스화 특성이 우수한 특징을 가지고 있으며, 구성성분 내 중금속, 황, 질소를 거의 함유하지 않는 점에서 환경오염 저감과 동시에 대체 신에너지로써 각광을 받고 있다. 이에 본 연구에서는 목질계 바이오매스인 Wood pellet (미송)에 대하여 고정층 반응기를 이용하여 질소분위기하에서 온도 및 Steam/Biomass Ratio(이하 SBR) 조건에 따른 가스화 특성으로 고찰하는데 그 목적을 둔다. 온도의 영향에 대하여, 높은 온도 범위에서 수소 수율이 증가함을 알 수 있었다. SBR에 대한 영향으로서, 저온 (700, $800^{\circ}C$)에서는 SBR=1에서는 수소의 수율이 증가하였으나 SBR=2, 3에서 감소하는 것을 보였다. 하지만 $900^{\circ}C$에서는 SBR이 증가 할수록 수소의 수율이 증가하는 것으로 나타났다. 또한 볼륨비로 나타내었을 경우 $H_2/CO(vol/vol)$의 경우 $900^{\circ}C$, SBR=3에서 0.73%로 water gas shift reaction이 가장 잘 일어난 것을 확인했고, $H_2/CH_4(vol/vol)$의 경우 마찬가지로 위의 조건과 동일조건에서 2.59%로 steam reforming이 가장 잘 일어난 것을 확인할 수 있었다. 최종적으로 본 실험에서는 $900^{\circ}C$, SBR=3인 경우에 가장 높은 수소수율을 얻을 수 있으며, 이때 수소의 수율은 32.7 Vol%였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.24-28
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• 2006

Electrochemical hydrogenation/dehydrogenation properties were studied for a single particle of a Mm-based(Mm : misch metal) hydrogen storage alloy($MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3}$) for the anode of Ni-MH batteries. A carbon fiber microelectrode was manipulated to make electrical contact with an alloy particle, and the cyclic voltammetry and the galvanostatic charge/discharge experiments were performed. A single particle of the alloy showed the discharge capacity of 280[mAh/g], the value being 90[%] of the theoretical capacity. Data were compared with that of the composite film consisting of the alloy particles and a polymer binder, which is more practical form for Ni-MH batteries. Additionally, pulverization of the alloy particles are directly observed. Compared with the conventional composite film electrodes, the single particle measurements using the microelectrode gave more detailed, true information about the hydrogen storage alloy.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.629-636
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• 2022

Domestic eco-friendly vehicles currently account for 5.8% of the total registered vehicles in Korea. Hydrogen vehicles, one of the representative eco-friendly vehicles, have grown rapidly as they have been expanded to the market based on the government's policy to boost the hydrogen industry. Therefore, it is time to expand the safety review of hydrogen vehicles in various directions according to the increase in supply. In this study, the effect of internal heat damage was analyzed when a jet flame was generated by a hydrogen car in a road tunnel. It was simulated using Fluent, and the amount of jet flame injection was selected in consideration of the hydrogen tank capacity of commercial hydrogen vehicles for road tunnels. In addition, the study was conducted with the direction of the jet flame and the nozzle distance from the tunnel wall as variables. From the results, when the jet flame erupted in the road tunnel, high radiant heat emission of more than 20 kW/m² was generated in most areas within ±5 m in the longitudinal direction based on the vehicle (spray nozzle) and 5 to 7 m in the lateral direction based on the adjacent tunnel wall.

• Environmental and Resource Economics Review
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• v.31 no.4
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• pp.645-668
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• 2022

Hydrogen energy is emerging as an important means of carbon neutrality in the various sectors including power, transportation, storage, and industrial processes. Fuel cell power plants are the fastest spreading in the hydrogen ecosystem and are one of the key power sources among means of implementing carbon neutrality in 2050. However, high volatility in system marginal price (SMP) and renewable energy certificate (REC) prices, which affect the profits of fuel cell power plants, delay the investment timing and deployment. This study applied the real option methodology to analyze how the dual uncertainties in both SMP and REC prices affect the investment trigger price level in the irreversible investment decision of fuel cell power plants. The analysis is summarized into the following three. First, under the current Renewable Portfolio Standard (RPS), dual price uncertainties passed on to plant owners has significantly increased the investment trigger price relative to one under the deterministic price case. Second, reducing the volatility of REC price by half of the current level caused a significant drop in investment trigger prices and its investment trigger price is similar to one caused by offering one additional REC multiplier. Third, investment trigger price based on gray hydrogen and green hydrogen were analyzed along with the existing byproduct hydrogen-based fuel cells, and in the case of gray hydrogen, economic feasibility were narrowed significantly with green hydrogen when carbon costs were applied. The results of this study suggest that the current RPS system works as an obstacle to the deployment of fuel cell power plants, and policy that provides more stable revenue to plants is needed to build a more cost-effective and stable hydrogen ecosystem.

• Journal of Hydrogen and New Energy
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• v.32 no.4
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• pp.277-284
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• 2021

This paper deals with multi-objective optimization using response surface method to improve the hydraulic performances of a 2 vane pump for wastewater treatment. For analyzing the internal flow field in the pump, steady Reynolds-averaged Navier-Stokes equations were solved with the shear stress transport turbulence model as a turbulence closure model. The impeller and volute variables were defined in the shape of the 2 vane pump. The objective functions were set to satisfy the total head at the design flow rate as well as to improve the efficiency. The hydraulic performance of the optimally designed shape was verified by numerical analysis results.

• Membrane Journal
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• v.32 no.4
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• pp.218-226
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• 2022

Hydrogen, a carrier of large-capacity chemical and clean energy, is an important industrial gas widely used in the petrochemical industry and fuel cells. In particular, hydrogen is mainly produced from fossil fuels through steam reforming and gasification, and carbon dioxide is generated as a by-product. Therefore, in order to obtain high-purity hydrogen, carbon dioxide should be removed. This review focused on free-standing polymeric membranes and mixed-matrix membranes (MMMs) that separate hydrogen from carbon dioxide reported in units of Barrer [1 Barrer = 10^-10 cm³ (STP) × cm / (cm² × s × cmHg)]. By analyzing various recently reported papers, the structure, morphology, interaction, and preparation method of the membranes are discussed, and the structure-property relationship is understood to help find better membrane materials in the future. Robeson's upper bound limits for hydrogen/carbon dioxide separation were presented through reviewing the performance and characteristics of various separation membranes, and various MMMs that improve separation properties using technologies such as crosslinking, blending and heat treatment were discussed.