• New & Renewable Energy
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• v.5 no.3
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• pp.40-48
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• 2009

Recovered heat has been considered as a renewable energy in Europe since 2008 because its great effect on energy saving and carbon decreasing in plant process. Energy saving and decreasing green gas are critical issue today, so various technologies to save energy and decrease carbon dioxide in plant process have been applied to many industrial area. In this paper, the feasibility of condenser heat recovery by heat pump in power plant for district heating and fuel line preheating were reviewed by verifying energy (heat) balance and mass balance of power plant model. Some ways to compose proper system to recover heat of condenser are suggested and their possibilities are also reviewed. Limitations on heat recovery in power plant are also reviewed. The results are verified by calculating input/output energy based on actual performance test data of Taean Thermal Power Plant in Korea. There is noticeable improvement of plant performance in some cases which demand low temperature (<100 C) heat like distrcit heating, fuel line heating, and so forth.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.1
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• pp.60-68
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• 2009

The steam reformer for hydrogen production from methane is studied by a numerical method. Langmuir- Hinshelwood model is incorporated for catalytic surface reactions, and the pseudo-homogeneous model is used to take into account local equilibrium phenomena between a catalyst and bulk gas. Dominant chemical reactions are Steam Reforming (SR) reaction, Water-Gas Shift (WGS) reaction, and Direct Steam Reforming (DSR) reaction. The numerical results are validated with experimental results at the same operating conditions. Using the validated code, parametric study has been numerically performed in view of the steam reformer performance. As increasing a wall temperature, the fuel conversion increases due to the high heat transfer rate. When Steam to Carbon Ratio (SCR) increases, the concentration of carbon monoxide decreases since WGS reaction becomes more active. When increasing Gas Hourly Space Velocity (GHSV), the fuel conversion decreases due to the heat transfer limitation and the low residence time. The reactor shape effects are also investigated. The length and radius of cylindrical reactors are changed at the same catalyst volume. The longer steam reformer is, the better steam reformer performs. However, system energy efficiency decreases due to the large pressure drop.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.79-84
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• 2024

Methane is an abundant and renewable hydrocarbon, but it causes global warming as a greenhouse gas. Therefore, methods to convert methane into useful chemicals or energy sources are needed. Methanol is a simple and abundant chemical that can be synthesized by the partial oxidation of methane. Methanol can be used as a chemical feedstock or a transportation fuel, as well as a fuel for low-temperature fuel cells. However, the electrochemical oxidation of methanol is a complex and multi-step reaction. To understand and optimize this reaction, new electrocatalysts and reaction mechanisms are required. This review discusses the methanol oxidation reaction mechanism, recent research trends, and future research directions.

• Journal of Climate Change Research
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• v.5 no.3
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• pp.189-197
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• 2014

Carbon footprint of apple was a sum of $CO_2$ emission in the step of manufacturing waste of agri-materials, and greenhouse gas emission during apple cultivation. Input amount of agri-materials was calculated on 2007 Income reference of Apple by Rural Development Administration. Emission factor of each agri- materials was based on domestic data and Ecoinvent data. $N_2O$ emission factor was based on 1996 IPCC guideline. Carbon dioxide was emitted 0.64 kg $CO_2$ to produce 1 kg apple fruit, and carbon dioxide was emitted 43.6% in the step of the manufacturing byproduct fertilizer, 1.3% in the step of the manufacturing single fertilizer, 4.7% in the step of the manufacturing composite fertilizer, 6.3% in the step of the manufacturing agri-chemicals, 14.6% in the step of the manufacturing fuel, 11.5% in the step of the fuel combustion, 17.7% of $N_2O$ emission by nitrogen application and 0.18% of disposal of agri-materials. It is needed for farmers to use fertilization recommendation based on soil testing (soil. rda.go.kr) because scientific fertilization is a major tools to reduce carbon dioxide of apple production. The fertilization recommendation could be also basic data in Measurable-ReporTablele-Verifiable (MRV) system for carbon footprint.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.555-561
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• 2023

In this study, we proposed a standard model for the design, construction and demonstration of the technology development and substantiation of small hydrogen powered vessel in order to respond to the alternative fuel-using vessel market that requires the use of low-carbon/carbon-free fuel as a greenhouse gas reduction measure. The hydrogen fuel cell-based electric propulsion system developed through this is optimized through performance and durability tests on the land-based test site (LBTS), and the electric propulsion system applied to this result is mounted on a small hydrogen propulsion vessel and operated. Simultaneously, through the digital twin technology between the LBTS and the hydrogen-propelled vessel on the sea, the technology that can predict and diagnose the problems that can occur in the electric propulsion system of the vessel is applied to carry out the empirical study of the hydrogen-propelled vessel. In addition, we propose a commercialization model by analyzing the economic feasibility of the demonstration vessel.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.2
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• pp.114-121
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• 2009

There are increased in using the bio-ethanol, as the carbon neutral attracts many researchers due to a reduction in carbon dioxide spotted as the global warming gas. A gasoline engine with 100% of the bioethanol was developed and used in Brazil already, but researches of using the bio-ethanol in diesel engines are lack. In this study, combustion tests with blend fuel of the gas oil and bio ethanol by 50% maximally due to a low cetane number of bio-ethanol were accomplished as a basic study of introduction of using the bioethanol in diesel engines. The result was that smoke emission was decreased with increase in proportion of the bio-ethanol, due to the increase of a amount of pre-mixed combustion with ignition delay. Although the amount of $CO_2$ is reduced according as the bio-ethanol is used(carbon neutral), the emission of $CO_2$ with increase in the proportion of the bio-ethanol was more increased due to lower a heat value of bio-ethanol than gas oil.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.549-555
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• 2019

Electrocatalysis of oxygen reduction reaction (ORR) using Pt nanoparticles or bimetal on carabon was studied. Currently, the best catalyst is platinum, which is a limited resource and expensive to commercialize. In this paper, we investigated the cheaper and more active electrocatalysts by making Pt nanoparticles and adding 3D transition metal such as copper. Electrocatalysts were obtained by chemical reduction based on ethylene glycol solutions. Elemental analysis and particle size were confirmed by XRD and TEM. The electrochemical surface area (ECSA) and activity of the catalyst were determined by electrochemical techniques such as cyclic voltammetry and linear sweep voltammetry method. The commercialized Pt support on carbon (Pt/C, JM), synthesis Pt/C and synthesis Pt3Cu1 alloy nanoparticles supported on carbon were compared. We confirmed that the synthesized Pt3-Cu1/C has high electrochemical performance than commercial Pt/C. It is expected to develop an electrocatalyst with high activity at low price by increasing the oxygen reduction reaction rate of the fuel cell.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.70-70
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• 2013

As the costs of carbon-footprinetd fuels grow continuously and simultaneously atmospheric carbon dioxide concentration increases, solar fuels are receiving growing attention as alternative clean energy carriers. These fuels include molecular hydrogen and hydrogen peroxide produced from water, and hydrocarbons converted from carbon dioxide. For high efficiency solar fuel production, not only light absorbers (oxide semiconductors, Si, inorganic complexes, etc) should absorb most sunlight, but also charge separation and interfacial charge transfers need to occur efficiently. With this in mind, this talk will introduce the fundamentals of solar fuel production and artificial photosynthesis, and then discuss in detail on photoelectrochemical (PEC) water splitting and CO2 conversion. This talk largely divides into two section: PEC water oxidation and PEC CO2 reduction. The former is very important for proton-coupled electron transfer to CO2. For this oxidation, a variety of oxide semiconductors have been tested including TiO2, ZnO, WO3, BiVO4, and Fe2O3. Although they are essentially capable of oxidizing water into molecular oxygen, the efficiency is very low primarily because of high overpotentials and slow kinetics. This challenge has been overcome by coupling with oxygen evolving catalysts (OECs) and/or doping donor elements. In the latter, surface-modified p-Si electrodes are fabricated to absorb visible light and catalyze the CO2 reduction. For modification, metal nanoparticles are electrodeposited on the p-Si and their PEC performance is compared.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.478-485
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• 2022

The certification performance issued through an external business is sold to companies subject to the emission trading system allocation, and the company subject to the allocation can secure the quota by converting the purchased external business certification performance into offset credits. In this methodology, when fossil fuels that used existing oil boilers (by oil type) were replaced with boilers using propane gas with a relatively low carbon content, the amount of carbon dioxide emission reduction by oil type was recognized. As an initial analysis to make up for the insufficient quota of large corporations, the amount of carbon reduction emissions and emission rights trading was calculated.

• Journal of ILASS-Korea
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• v.28 no.2
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• pp.55-61
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• 2023

Natural gas is a high-octane fuel that is effective in controlling knocking combustion. In addition, as a low-carbon fuel with a high hydrogen-carbon ratio, it emits less carbon dioxide and almost no particulate matter compared to conventional fossil fuels. Stoichiometric combustion engines equipped with a three-way catalyst are useful in various fields such as transportation and power generation because of their excellent exhaust emission reduction performance. However, stoichiometric combustion engines have a disadvantage of lower thermal efficiency compared to lean combustion engines. In this study, a combination of high compression ratio and Atkinson cycle was implemented in a 11 liter, 6-cylinder, spark-ignition engine to improve the thermal efficiency of the stoichiometric engine. As a result, pumping and friction losses were reduced and the operating range was extended with optimized Atkinson camshaft. Based on the exhaust gas limit temperature of 730℃, the maximum load and thermal efficiency were improved to BMEP 0.66 MPa and BTE 35.7% respectively.