• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.164-173
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• 2015

This study aims to design energy supply systems from various energy sources for transportation sectors and comparatively analyze the life cycle cost of different scenario-based systems. For components of the proposed energy supply system, we consider a typical oil refinery, byproduct hydrogen system, renewable energy source (RES)-based electric generation system and existing electricity grid. We also include three types of vehicles in transportation sector such as internal combustion engine vehicle (ICEV), electric vehicle (EV), fuel cell vehicle (FCV). We then develop various energy supply scenarios which consist of such components and evaluate the economic performance of different systems from the viewpoint of life cycle cost. Finally we illustrate the applicability of the proposed framework by conducting the design problem of energy supply systems of Jeju, Korea. As the results of life cycle cost analysis, EV fueled by electricity from grid is the most economically feasible. In addition, we identify key parameters to contribute the total life cycle cost such as fuel cost, vehicle cost, infra cost and maintenance cost using sensitivity analysis.

• Korean Journal of Materials Research
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• v.24 no.8
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• pp.434-442
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• 2014

Serious environmental problems have been caused by the greenhouse effect due to carbon dioxide($CO_2$) or nitrogen oxides($NO_x$) generated by the use of fossil fuels, including oil and liquefied natural gas. Many countries, including our own, the United States, those of the European Union and other developed countries around the world; have shown growing interest in clean energy, and have been concentrating on the development of new energy-saving materials and devices. Typical non-fossil-fuel sources include solar cells, wind power, tidal power, nuclear power, and fuel cells. In particular, organic solar cells(OSCs) have relatively low power-conversion efficiency(PCE) in comparison with inorganic(silicon) based solar cells, compound semiconductor solar cells and the CIGS [$Cu(In_{1-x}Ga_x)Se_2$] thin film solar cells. Recently, organic cell efficiencies greater than 10 % have been obtained by means of the development of new organic semiconducting materials, which feature improvements in crystalline properties, as well as in the quantum-dot nano-structure of the active layers. In this paper, a brief overview of solar cells in general is presented. In particular, the current development status of the next-generation OSCs including their operation principle, device-manufacturing processes, and improvements in the PCE are described.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3049-3052
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• 2008

MCFC(molten carbonate fuel cell) power generation system is prime candidate for the utilization of fossil based fuels to generate ultra clean power with a high efficiency. In the MCFC power plant system, a combustor performs a role to supply high temperature mixture gases for cathode and heat for reformer by using the stack off-gas of the anode which includes a high concentration of $H_2O$ and $CO_2$. Since a combustor needs to be operated in a very lean condition and to avoid excessive local heating, catalytic combustor is usually used. The catalytic combustion is accomplished by the catalytic chemical reaction between fuel and oxidizer at catalyst surface, different from conventional combustion. In this study, a mathematical model for the prediction of internal flow and catalytic combustion characteristics in the catalytic combustor adopted in the MCFC power plant system is suggested by using the numerical methods. The numerical simulation models are then implemented into the commercial CFD code. After verifying result by comparing with the experimental data and calibrated kinetic parameters of catalytic combustion reaction, a numerical simulation is performed to investigate the variation of flow and combustion characteristics by changing such various parameters as inlet configuration and inlet temperature. The result show that the catalytic combustion can be effectively improved for most of the case by using the perforated plate and subsequent stable catalytic combustion is expected.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.11
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• pp.889-897
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• 2014

This paper presents a method for finding an optimized result by using a genetic algorithm (GA) based on a PEMFC analysis result. The conventional analysis method designs fuel cells one-by-one, and each result is compared to obtain the best performance. Because the computational burden of the conventional analysis is enormous, the present optimization process provides an inefficient tool by automatically setting the boundary and material properties and mesh generation. As the change can be reflected automatically in the channel geometry with GA, the fuel cell analysis result with various sizes can be obtained easily. Therefore, the global maximum performance can be obtained through a GA optimization procedure.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.1-10
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• 2024

In this study, we constructed a process simulation model for an agricultural by-products based Solid Oxide Fuel Cell (SOFC) combined heat and power generation system as part of the introduction of technology for energy self-sufficiency in the agricultural sector. The aim was to reduce the burden of increasing fuel and electricity consumption due to rapid fluctuations in international oil prices and the expansion of smart farming in domestic farms, while contributing to the national greenhouse gas reduction goals. Based on the experimental results of 0.3 ton/day torrefied agricultural by-product gasification experiment, a model for an agricultural by-product-based SOFC cogeneration system was constructed, and optimization of the heat exchange network was conducted for SOFC capacities ranging from 4 to 20 kW. The results indicated that an 8 kW agricultural by-product-based SOFC cogeneration system was optimal under the current system conditions. It is anticipated that these research findings can serve as foundational data for future commercial facility design.

• Journal of Power Electronics
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• v.5 no.2
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• pp.99-103
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• 2005

In this paper, a novel circuit topology of a three-winding coupling inductor-assisting a high-frequency PWM boost chopper type DC-DC power converter with a high boost voltage conversion ratio and low switch voltage stress is proposed for the new energy interfaced DC power conditioner in solar photovoltaic and fuel cell generation systems. The operating principle in a steady state is described by using its equivalent circuits under the practical condition of energy processing of a lossless capacitive snubber. The newly-proposed power MOSFET boost chopper type DC-DC power converter with the three-winding coupled inductor type transformer and a single lossless capacitor snubber is built and tested for an output power of 500W. Utilizing the lower voltage and internal resistance power MOSFET switch in the proposed PWM boost chopper type DC-DC power converter can reduce the conduction losses of the active power switch compared to the conventional model. Therefore, the total actual power conversion efficiency under a condition of the nominal rated output power is estimated to be 81.1 ％, which is 3.7％ higher than the conventional PWM boost chopper DC power conversion circuit topology.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.683-686
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• 2001

This paper presents a novel prototype of the utility­interactive voltage source type sinewave pulse modulated power inverter using a high-frequency flyback transformer link. The proposed power conditioner circuit for the solar photovoltaic generation and small scale fuel cell has an isolation function due to the safety of the power processing system, which is more cost effective and acceptable for the small-scale distributed renewal energy conditioning and processing systems. The discontinuous current mode(DCM) of this power processing conversion circuit is applied to implement a simple circuit topology and pulse modulated control scheme. Its operation principle is described on the basis of simulation evaluations and theoretical considerations. The simulation results obtained herein prove that the proposed inverter outputs with sinusoidal waveforms and unity power factor currents are synchronized to the main voltage in utility power source grid. In this paper, the soft switching topology of high­frequency linked sinewave pulse modulation inverter is proposed and discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.268-272
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• 2005

현재 국내 수소 관련 연구는 생산, 운반, 저장 등 공급과정의 기술과 발전, 수송 등 이용기술을 중심으로 이루어지고 있다. 본 연구에서는 현재 개발 중인 MCFC 발전설비에 대한 기술 및 비용 특성을 이용하여 LEAP모형시스템 기반의 ROK2003-H2 모형을 구축하고 정부의 '제2차 신재생에너지 기술개발 및 이용보급 기본계획$(2003\~2012)$'의 계획에 따른 수소에너지(연료전지) 보급의 에너지/환경부문 파급효과를 분석한다. 분석 대상이 되는 기술은 Molten Carbonate 연료전지를 이용한 2MW급 발전기술로, 2008년 70MW가 설치되기 시작하여 2011년까지 매년 100MW증설되어 2011년 전체 설비가 370MW에 이르는 것으로 시나리오를 구축한다. 설비의 에너지효율성은 연료전지 발전설비가 처음 도입된 2008년에는 $45\%$로 가정하고 2009년-2011년 간에 $5\%$씩 상승되어 2011년에는 $60\%$에 이를 것으로 전망한다. 분석결과에 의하면 2011년에 연료전지의 발전설비를 370MW로 확대하는 경우에 CO를 비롯한 대부분의 대기오염배출량이 감소하며, 온실가스 배출량 역시 35,433백만tC로 약 295백만tC가 감소한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.11
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• pp.57-68
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• 2013

The market for distributed power generation based on renewable energy is increasing, particularly for standalone mini-grid applications in developing countries with limited energy resources. Stand-alone power systems (SAPS) are of special interest combined with renewable energy design in areas not connected to the electric grid. Traditionally, such systems have been powered by diesel engine generator sets (DEGS), but also hybrid systems with photovoltaic and/or wind energy conversion systems (WECS) are becoming quite common nowadays. Hybrid energy systems can now be used to generate energy consumed in remote areas and stand-alone microgrids. This paper describes the design, simulation and feasibility study of a hybrid energy system for a stand-alone power system. A simulated model is developed to investigate the design and performance of stand-alone hydrogen renewable energy systems. The analysis presented here is based on transient system simulation program (TRNSYS) with realistic ventilation load of a large store. Design of a hybrid energy system is site specific and depends on the resources available and the load demand.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.6
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• pp.642-648
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• 2017

The use of fossil is causing enviromental all over the world. So hydrogen energy is attracting attention as one of the alternative. The government announced that 30% of the air pollution is because of the Internal Combustion Engine Vehicle. In addition, they plans to reduce Internal Combustion Engine Vehicles by 2030 and increase (electric vehicles, EV) or (fuel cell vehicle, FCV). The FCV is evaluated as a next-generation green car because it has a long driving distance and short charging time. However, the hydrogen industry is not able to expand due to the lack of refueling infrastrucutre. This paper predicts the site of hydrogen refueling stations for the expansion of the hydrogen industry and proposes a method to supply hydrogen multi energy filling stations.