• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.562-574
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• 2023

Carbon neutrality has been suggested to overcome the global climate crisis caused by global climate change. Hydrogen energy is a major way to achieve carbon neutrality, and the developments and policies of hydrogen technology have been proposed to achieve this goal. To commercialize hydrogen energy resources, it is necessary to understand the overall value chain composed of hydrogen production, storage, and utilization and to present the direction of technological developments. In this paper the hydrogen strategies of major countries, including Europe, the United States, Japan, China, and South Korea will be analyzed, and hydrogen technologies by value chain will also be explain. This paper will contribute to understanding the overall hydrogen policy and technology, as both policy and technology are summarized.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1288-1294
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• 2022

Hydrogen as an environmentally friendly energy carrier has received special attention to solving uncertainty about the presence of renewable energy and its dependence on time and weather conditions. This material can be prepared from different sources and in various ways. In previous studies, fossil fuels have been used in hydrogen production, but due to several limitations, especially the limitation of the access to this material in the not-too-distant future and the great problem of greenhouse gas emissions during hydrogen production methods. New methods based on renewable and green energy sources as energy drivers of hydrogen production have been considered. In these methods, water or biomass materials are used as the raw material for hydrogen production. In this article, after a brief review of different hydrogen production methods concerning the required raw material, these methods are examined and ranked from different aspects of economic, social, environmental, and energy and exergy analysis sustainability. In the following, the current position of hydrogen production is discussed. Finally, according to the introduced methods, their advantages, and disadvantages, solar electrolysis as a method of hydrogen production on a small scale and hydrogen production by thermochemical method on a large scale are introduced as the preferred methods.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.607-615
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• 2022

In this study, economic analysis program was developed for economic evaluation of hydrogen production, storage/delivery, and utilization technologies as well as overseas import of hydrogen. Economic analysis program can be used for the estimation of the levelized cost of hydrogen for hydrogen supply chain technologies. This program include five hydrogen production technology on steam methane reforming and water electrolysis, two hydrogen storage technologies (high compressed gas and liquid hydrogen storage), three hydrogen delivery technologies (compressed gas delivery using tube trailer, liquid hydrogen, and pipeline transportation) and six hydrogen utilization technologies on hydrogen refueling station and stationary fuel cell system. In the case of overseas import hydrogen, it was considered to be imported from five countries (Austraila, Chile, India, Morocco, and UAE), and the transportation methods was based on liquid hydrogen, ammonia, and liquid organic hydrogen carrier. Economic analysis program that was developed in this study can be expected to utilize for planning a detailed implementation methods and hydrogen supply strategies for the hydrogen economy road map of government.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.1
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• pp.61-66
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• 2022

In order to introduce the hydrogen economy and increase supply, research in the field of hydrogen production is being actively conducted. Among the hydrogen production methods, the method of steam reforming from natural gas and producing it currently accounts for about 50% of the global hydrogen production. In the method of steam reforming process, hydrogen can be produced by adding a reformer to an existing natural gas supply pipe. Because of these advantages, it is evaluated as a realistic production method at present in Korea, where the city gas supply chain is well established. But there is concern in that it is highly likely to be installed in downtown areas and residential spaces. In this study, the risk of the process of steam reforming to produce hydrogen was reviewed.

• Environmental Engineering Research
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• v.10 no.1
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• pp.7-14
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• 2005

The feasibility of hydrogen production with a raw seed sludge through direct acclimation of feedstock was investigated at acidogenic stage, and methane was harvested at followed methanogenic stage in an anaerobic two-stage process. Hydrogen content was higher than 57% at all tested organic loading rates (OLRs) and the yield of hydrogen ranged from 1.5 to 2.4 mol H2/mol hexose consumed and peaked at 6 gVSl-1day-1. Normal butyrate and acetate were main volatile fatty acids (VFAs), whereas the concentration of propionate was insignificant. The hydrogen-producing bacteria, Clostridium thermosaccharolyticum, was detected with strong intensity at all tested organic loading rates (OLRs) by denaturing gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) analysis. From COD balance in the process, the fraction of the feed-COD converted to the hydrogen-COD at acidogenic stage ranged from 7.9% to 9.3% and peaked at 6 gVSl-1day-1, whereas the fraction of feed-COD converted to the methane-COD at methanogenic stage ranged from 66.2% to 72.3% and peaked at 3 gVSl-1day-1.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.623-635
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• 2022

As global warming accelerates, clean hydrogen production becomes more important to mitigate it. However, importing hydrogen is necessary for countries that have high energy demands but insufficient resources to produce clean hydrogen. In line with the trend, this study investigated both the economic and environmental viability of an overseas hydrogen supply chain between Australia and the Republic of Korea. Several possible methods of water electrolysis and hydrogen carriers are compared and effect of renewable electricity price on the cost of hydrogen production is evaluated.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.2
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• pp.191-197
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• 2012

The hydrogen storage is one of the key technologies to achieve the successful hydrogen economy and a chain to connect hydrogen production to its utilization. In this paper, characteristics and strong candidates of hydrogen storage technologies were analyzed from the objective information of patents. Also, the hydrogen storage technology trends and gaps were assessed using statistical or qualitative analysis. In this study the patents applied in Korea, Japan, US and EU from 10 or 20 years ago to 2011 were analyzed. The result of patent analysis could be used for developing or searching for promising technology of the hydrogen storage.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.34-50
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• 2022

Since the Paris climate agreement, reducing greenhouse gases has been the most important global issue. In particular, it is necessary to reduce fossil fuels in the mobility sector, which accounts for a significant portion of total greenhouse gas emissions. In this paper, we investigated the economic feasibility of green mobility energy supply chains, which supply hydrogen as fuel to hydrogen vehicles based on electricity from renewable energy sources. The design and operation costs were analyzed by evaluating nine scenarios representing various combinatorial possibilities such as renewable energy generation, hydrogen production through water electrolytes, hydrogen storage and hydrogen refueling stations. Simulation calculations were made using Homer Pro, widely used commercial software in the field. The experience gained in this study could be further utilized to construct actual hydrogen energy systems.

• Polymer(Korea)
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• v.32 no.6
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• pp.566-572
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• 2008

Polyethylene has been prepared via metallocene catalysts [(TMDS)$Cp_2$]$ZrCl_2$, 1, and [$(n-Bu)_2Cp_2$]$ZrCl_2$, 2, in the presence of hydrogen as a chain transfer reagent. Increase of hydrogen flow to the polymerization reactor resulted in the drop of catalytic activity, reduction of molecular weight of polyethylene, getting narrow of molecular weight distribution of polyethylene, and melting point of the polyethylene wax. It should be noticed that it was possible to control molecular weight down to 1500 and melting temperature to 60 $^\circ$C of polyethylene wax using the catalyst 1 that has been developed by authors as well as the catalyst 2 from Exxon.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.631-633
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• 2005

For biohydrogen production, hydrogenase is a key enzyme. In the present work we performed search of [NiFe]-hydrogenases from hydrogen producing microorganisms using degenerate polymerase chain reaction (PCR) strategy. Degenerate primers were designed from the conserved region of [NiFe]-hydrogenase group I especially on structural genes encoding for catalytic subunit of [NiFe]-hydrogenase from bacteria producing hydrogen. Most of [NiFe]-hydrogenase (group I) are expressed via complex mechanism with aid of auxiliary protein and localized through twin-arginine translocation pathway. [NiFe]-hydrogenase is composed of large and small subunits for catalytic activity. It is known that only small subunit has signal peptide for periplasmic localization and large & small subunitscome together before localization. During this process, large subunit is treated by endopeptidase for maturation. Based on these information we used signal peptide sequence and C-terminal of large subunit by recognized by endopeptidase as templates for degenerate primers. About 2,900 bp of PCR products were successfully amplified using the designed degenerate primers from genomic DNAs of several microorganisms. The amplified PCR products were inserted into T-vector and then sequenced to confirm.