• Korean Journal of Materials Research
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• v.31 no.9
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• pp.525-531
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• 2021

Carbon-encapsulated Ni catalysts are synthesized by an electrical explosion of wires (EEW) method and applied for CO₂ methanation. We find that the presence of carbon shell on Ni nanoparticles as catalyst can positively affect CO₂ methanation reaction. Ni@5C that is produced under 5 % CH₄ partial pressure in Ar gas has highest conversions of 68 % at 350 ℃ and 70 % at 400 ℃, which are 73 and 75 % of the thermodynamic equilibrium conversion, respectively. The catalyst of Ni@10C with thicker carbon layer shows much reduced activity. The EEW-produced Ni catalysts with low specific surface area outperform Ni catalysts with high surface area synthesized by solution-based precipitation methods. Our finding in this study shows the possibility of utilizing carbon-encapsulated metal catalysts for heterogeneous catalysis reaction including CO₂ methanation. Furthermore, EEW, which is a highly promising method for massive production of metal nanoparticles, can be applied for various catalysis system, requiring scaled-up synthesis of catalysts.

• Journal of Climate Change Research
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• v.8 no.4
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• pp.377-384
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• 2017

Amid growing concerns about energy security, energy prices, economic competitiveness, and climate change, district heating (DH) system has been recognized for its significant benefits and the part it can play in efficiently meeting society's growing energy demands while reducing environmental impacts. Policy makers often need to quantify the fuel and carbon dioxide ($CO_2$) emissions savings of DH system compared to conventional individual heating (IH) system in order to estimate its actual emissions reductions. The objective of this paper is to calculate energy efficiency and $CO_2$ emissions saving, and to propose the future direction for DH system in Korea. DH system achieved total system efficiencies of 67.9% compared to 54.1% for IH system in 2015. DH system reduced $CO_2$ emissions by $381,311ton-CO_2$ (4.1%) compared to IH system. The results suggest that DH system is more preferred than IH system using natural gas. In Korea, the aim is to reduce dependence on fossil fuels and to use energy more efficiently. DH system have significant potential with regard to achieving this aim, because DH system are already integrated with power generation in the electricity since combined heating and power (CHP) are used for heat supply. Although the future conditions for DH may look promising, the current DH system in Korea must be enhanced in order to handle future competition. Thus, the next DH system must be integrated with multiple renewable energy and waste heat energy sources.

• Journal of the Korean Ceramic Society
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• v.44 no.8
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• pp.424-429
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• 2007

Novel conductive $CO_2$ membranes composed of dual phases, molten carbonates and electronic conducting ceramics, were investigated. As the microstructure control of electronic conducting ceramic supports is extremely important to keep the molten carbonates stable in the membranes by a capillary force applied by the pore structure of the supports, we have scrutinized the microstructure of the electronic conducting supports utilizing microscopic images and gas permeability measurement. From the evaluation of the electrical conductivities of the molten carbonates and the electronic conducting ceramic supports, we found that the ionic conductivity of the molten carbonates could determine $CO_2$ flux through the dual phase membranes if the surface exchange rate were relatively high enough.

• Korean System Dynamics Review
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• v.14 no.4
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• pp.91-112
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• 2013

This article aims at revealing the dynamic relationships between the energy R&D investment and economic growth in Korea. To achieve this goal, we reviewed the effects of energy R&D investments and tried to make the holistic interconnections for describing the feedback loops between energy R&D and economic system. Energy R&D investments develop the renewable energy, energy efficiency and $CO_2$ emission reductions technologies for accomplishing the national strategic targets. The rapid obsolescence of technologies makes the inefficiency and negative effects in governmental energy R&D investments.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1657-1663
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• 2022

This study uses data from 1970 to 2016 to analyze the effect of nuclear energy use on CO₂ emissions and attempts to validate the EKC hypothesis using the Fourier Autoregressive Distributive Lag model in India for the first time. Because of India's rapidly rising population, the environment is being severely strained. However, with 22 operational nuclear reactors, India boasts tremendous nuclear energy potential to cut down on CO₂ emissions. The EKC is validated in India as the significant coefficients of GDP and GDP.² The short-run estimates also suggest that most environmental externalities are corrected within a year. Given the findings, some policy recommendations abound. The negative statistically significant coefficient of nuclear energy consumption is an indication that nuclear power expansion is essential to achieving clean and sustainable growth as a policy goal. Also, policymakers should enact new environmental laws that support the expansion and responsible use of nuclear energy as it is cleaner than fossil fuels and reduces the cost and over-dependence on oil, which ultimately leads to higher economic growth in the long run. Future research should consider studying the nonlinearities in the nuclear energy-CO₂ emissions nexus as the current study is examined in the linear sense.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2019.05a
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• pp.114-115
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• 2019

• Journal of Hydrogen and New Energy
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• v.29 no.5
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• pp.530-537
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• 2018

The effect of temperature and absorption capacity on heat of reaction, which is one of the characteristic studies of $CO_2$ absorption, were investigated in a differential reaction calorimeter (DRC) by using piperazine (PZ) and 2-methylpiperazine (2-MPZ). For all absorbents, $CO_2$ loading capacity decreased with increasing the temperature, while the heat of reaction increased, it figured out that these had a linear correlation between $CO_2$ loading capacity and/or heat of reaction and the temperature. The heat of reaction of all absorbents increased with increasing $CO_2$ loading capacity, especially 2-MPZ rapidly increased at $70^{\circ}C$. The reason for increase in the heat of reaction was occurred the regeneration of $CO_2$, which is a reverse-reaction, simultaneously with the absorption.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.70-75
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• 2014

The experiment was done on traveling at the speed of 20km/h, 60km/h and 100km/h using the performance testing mode for chassis dynamometer. The experimental method were employed to measure the waveform of secondary ignition coil and exhaust emission. In this experiment, the correlation between the secondary waveform coming from ignition coil and exhaust emission were measured in decrepit vehicle. The secondary waveform characterized by the value of effective discharge energy. The following results are obtained by analyzing the data relativity between the effective discharge energy and exhaust emission. The variation rate of effective discharge energy was largest 60km/h, 20km/h, 100km/h velocity in the ordered named. As the vehicle velocity increases, the average variation rate of CO and $NO_X$ decreases and that of HC and $CO_2$ decrease. The value of effective discharge energy, CO, $NO_X$ and fuel consumption is measured badly in case of car with failures in MAP, spark plug and good in case of car with before and after maintenance regardless of vehicle velocities. The value of effective discharge energy is to be nearly parabolic shape as vehicle velocity increases. As the value of effective discharge energy increases, the value of $NO_X$, HC and $CO_2$ decrease, the value of CO increase. The most sensible factors of exhaust emission were CO, $NO_X$, and the small variation factors were HC, $CO_2$.

• Membrane Journal
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• v.23 no.5
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• pp.367-374
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• 2013

In the present study, Pebax-2533 plate membranes were prepared by drying precursor solutions which were obtained by dissolving Pebax-2533 polymer in 1-Propanol/n-Butanol mixed solvents. And then the $CO_2$ and $N_2$ permeation behaviors were tested by using a time-lag system. The prepared Pebax-2533 plate membranes showed a considerable $CO_2/N_2$ separation performance : the $CO_2$ permeability was 130 to 288 barr, and the $CO_2/N_2$ permselectivity was 5-8. The $CO_2$ permeation data obtained by varying feed pressure, permeation temperature, and solvent composition announced that not only the $CO_2$ sorption but also the $CO_2$ diffusion is equally important in the overall $CO_2$ permeation.

• Journal of Hydrogen and New Energy
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• v.27 no.5
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• pp.554-561
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• 2016

Depending on the Bio-gas sources, main component gases of $CH_4$ and $CO_2$ are shown to be variously present in amounts. For the anaerobic digester, The concentration of $CH_4$ and $CO_2$ in the gases are 60~70 and 30~35 vol%. For the landfill gas, $CH_4$ and $CO_2$ are 40~60 and 40~60 vol%. For the food wastes, $CH_4$ and $CO_2$ are 60~80 and 20~40 vol%, respectively. In this study, maximum conversion rates of $CO_2$ were obtained from the variety of concentrations of $CH_4$ and $CO_2$ by the catalysts of reforming reactions. Moreover, in order to get maximum producing amount of synthetic gas, experimental studies were performed to optimize the reaction variables. On the basis of $CH_4$, 243 ml, R [$CH_4/(O2+CO_2)$] value were varied from 0.8 to 1.35, in the study of $CH_4$ and $CO_2$ reforming reactions. It was shown that the optimal results were obtained for 1.35 of R value. And also, at $850^{\circ}C$ and 1 atm, the production rate of synthetic gas was 90% and the conversion rates of $CH_4$ and $CO_2$ were higher than 99% and 90%, respectively.