• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.4
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• pp.529-545
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• 2013

Strong restrictions on emissions from marine power plants (particularly $SO_x$, $NO_x$) will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC) and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heat-recovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency.

• Journal of Climate Change Research
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• v.8 no.3
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• pp.213-220
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• 2017

The purpose of this study is to analyze effects of Greenhouse Gas (GHG) emission reduction in district energy business mainly based on Combined Heat and Power (CHP) plants. Firstly this paper compares the actual carbon intensity of power production between conventional power plants and district energy plants. To allocate the GHG from CHP plants, two of different methods which were Alternative Generation Method and Power Bonus Method, have been investigated. The carbon intensity of power production in district energy plants ($0.43tonCO_2e/MWh$) was relatively lower than conventional gas-fired power plants ($0.52tonCO_2e/MWh$). Secondly we assessed the cost effectiveness of reduction by district energy sector compared to the other means using TIMES model method. We find that GHG marginal abatement cost of 'expand CHP' scenario (-$134/ton$CO_2$) is even below than renewable energy scenario such as photovoltaic power generation ($87/ton$CO_2$). Finally the GHG emission reduction potential was reviewed on the projected GHG emission emitted when the same amount of energy produced in combination of conventional power plants and individual boilers as substitution of district energy. It showed there were 10.1~41.8% of GHG emission reduction potential in district energy compared to the combination of conventional power plants and individual boilers.

• The KSFM Journal of Fluid Machinery
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• v.12 no.2
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• pp.46-51
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• 2009

Recently, microturbines have received attention as a small-scale distributed power generator. Since the exhaust gas carries all of the heat release, generating hot water is usual method of heat recovery from microturbine CHP (combined heat and power) systems. The power of microturbines decreases as ambient temperature increases. This study predicted micoturbine power boost by injecting hot water generated by heat recovery. Influence of injecting water at two different locations was examined. Water injection improves power, but efficiency depends much on the injection location. Injecting water at the compressor discharge shows a much higher efficiency than the combustor injection. However, the combustor injection may have as much available cogeneration heat as the dry operation, while the available heat in the compressor discharge injection is much smaller than the dry operation.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.141-151
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• 2016

Recently, technology for energy recovery from waste has been increasing interest globally including the Korea. In Korea, we have interested in using biogas generated from the sewage treatment process. As one alternative, there are operating biogas combined heat and power plant. The generation amount of the Sewage Sludge are expected to grow in the future. For this reason, total processing cost of Sewage Sludge will increase. To solve this problem, it seems will be invested with the expansion of facilities that use biogas as energy. Therefore, quantitative information on such facilities is required. Thus, this study attempts to economic feasibility analysis for Seonam Biogas Combined Heat and Power Plant. Meanwhile, as the benefit items for economic feasibility analysis consider electricity supply benefit except for heat supply benefit. The average prices of electricity use were residence 123.69, commercial 130.46, and industry 102.59 won per kWh for the year 2015, In addition, the economic benefit are calculated to be residence 310.21, commercial 378.49, and industry 222.87 won per kWh. The results of economic feasibility analysis is NPV 72.18 billion won, B/C 1.90, IRR 37%, shows that economic validity of Seonam Biogas Combined Heat and Power Plant.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.183-186
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• 2001

This paper describes the optimal operation scheduling of total cogeneration system which is interconnected with combined heat power plant of utility and district heat devices. The numerical modeling about the cogeneration system and the auxiliary thermal energy devices are established and simulation is carried out by LINDO program in order to minimize the operation cost under the national viewpoint. The results reveal that the established numerical modeling and the operation strategy can be effectively applied to the total cogeneration systems to reduce the energy cost.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.12
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• pp.570-575
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• 2006

This paper develops methodology in order to consider CHP(Combined Heat and Power) capacity in the Basic Plan of Long Term Electricity Supply & Demand. We develop generating cost of CHP considering electric and heat. Also we develop mixed load duration curve which includes the electric load and heat load and then apply CHP capacity to SCM(Screening Curve Method) considering CHP feature. Accordingly, it decide the optimal CHP capacity in the Basic Plan of Long Term Electricity Supply & Demand. Also, We perform the sensitivity analysis according to cost variation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.162-163
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• 2022

Maritime transportation is going to transfer to alternative fuels as a result of the worldwide demands toward decarbonization and tougher maritime emissions regulations. Methanol is considered as a potential marine fuel, which has the ability to reduce SOx and CO₂ emissions, reduce climate change effects, and achieve the objective of green shipping. This work proposes and combines the innovative combination system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbines (GT), and organic Rankine cycles (ORC) for maritime vessels. The system's primary power source is the SOFC, while the GT and PEMFC use the waste heat from the SOFC to generate useful power and improve the system's ability to use waste heat. Each component's thermodynamics model and the combined system's model are established and examined. The multigeneration system's energy and exergy efficiency are 76.2% and 30.3%, respectively. When compared to a SOFC stand-alone system, the energy efficiency of the GT and PEMFC system is increased by 19.2%. The use of PEMFC linked SOFC has significant efficiency when a ship is being started or maneuvered and a quick response from the power and propulsion plant is required.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.102.2-102.2
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• 2010

We are to evaluate the stabilization technology of actual biogas plant facilities, which is operating currently. It describes the traits of the consistent facilities of mesophilic anaerobic digestion using Unison Biogas plant Recovery system(UBR). Also the economical efficiency is examined with the electric power sales earnings and applying the deserted heating by generating electric power, which is generated by operated combined heat and power using biogas produced by mesophilic anaerobic digestion. We have generated the 481,113kw for electric power and 1,376Gcal for thermal energy simultaneously. If these electric power and thermal energy are converted into diesel, we can achieve savings equal to 114,300L, and 152,109L in the quantity of heat. Finally, if CDM, RPS, liquid fertilizer sales business, etc. is activated, the earnings will be expected to improve dramatically and is considered to contribute a drop of the greenhouse gas.

• New & Renewable Energy
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• v.2 no.3
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• pp.15-22
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• 2006

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This new market penetration using the distributed generation technology is linked to a large number of factors like economics and performance, safety and reliability, market regulations, environmental issues, or grid connection standards. KEPCO, a government company in Korea, has performed the project to identify and evaluate the performance of Micro Gas Turbine(MGT) technologies focused on 30, 60kW-class grid-connected optimization and combined Heat & Power performance. This paper describes the results for the mechanical, electrical, and environmental tests of MGT on actual grid-connection under Korean regulations. As one of the achievements, the simulation model of Exhaust-gas Absorption Chiller was developed, so that it will be able to analyze or propose new distributed generation system using MGT. In addition, KEPCO carried out the field testing of the MGT Cogeneration system at the R&D Center Building, KEPCO. The field test was conducted in order to respond to a wide variety of needs for heat recovery and utilization. The suggested method and experience for the evaluation of the distributed generation will be used for the introduction of other distributed generation technologies into the grid in the future.

• The KSFM Journal of Fluid Machinery
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• v.20 no.1
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• pp.41-47
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• 2017

This study aimed to analyze organic Rankine cycle(ORC) which recovers discarded heat from a gas turbine based combined cycle cogeneration(CC-cogen) plant in terms of both performance and economics. The nominal electric power of the CC-cogen plant is around $120MW_e$, and heat for district heating is $153MW_{th}$. The major purpose of this study is to compare various options in selecting heat source of the ORC. Three heat sources were compared. Case 1 uses the exhaust gas from the HRSG, which is purely wasted to environment in normal plant operation without ORC. Case 2 also uses the exhaust gas from the HRSG. On the other hand, in this case, the DH economizer, which is located at the end of the HRSG, does not operate. Case 3 generates power using some of the district heating water which is supplied to consumers. The estimated ORC power generation ranges between 0.3 to 2.3% of the power generation capacity of the CC-cogen plant. Overall, Case 3 is evaluated to be better than other two options in terms of system design flexibility and power generation capacity.