• Title/Summary/Keyword: Energy costs

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Optimal Operation Scheme and Reliability Index Improvement of Micro Grid Using Energy Storage Systems (에너지 저장장치를 이용한 마이크로 그리드의 최적운영 및 신뢰도 지수 개선)

  • Kim, Kyu-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.2
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    • pp.205-210
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    • 2014
  • The micro grid considered in this paper consists of a diesel generator, a photovoltaic array, a wind turbine, a fuel cell, and a energy storage system. This paper explains and simulates the micro grid components in terms of accuracy and efficiency of having a system model based on the costs of fuel as well as operation and maintenance. For operational efficiency, the objective function in a diesel generator consists of the fuel cost function similar to the cost functions used for the conventional fossil-fuel generating plants. The wind turbine generator is modeled by the characteristics of variable output. The optimization is aimed at minimizing the cost function of the system while constraining it to meet the customer demand and safety of micro grid. The operating cost in fuel-cell system includes the fuel costs and the efficiency for fuel to generate electric power. To develop the overall system model gives a possibility to minimize of the total cost of micro grid. The application of optimal operation can save the interruption costs as well as the operating costs, and improve reliability index in micro grid.

Environmental awareness and economical profits of replacing gas turbines in gas compressor stations: A case study of Polkalleh station in Iran

  • Sadrnejad, Amin;Noorollahi, Younes;Sadrnejad, Tohid
    • Environmental Engineering Research
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    • v.21 no.2
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    • pp.132-139
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    • 2016
  • In early 90s the worldwide awareness about the energy crisis and global warming had been increased and emission reduction (by improving energy efficiency), as well as increasing the capacity of clean and renewable energies, showed themselves as the most important steps towards the sustainable development approach. However, investigations on Iran's environmental situation show huge decline in recent decades and apparently there is no sense of urgency about these issues through the vision of Iranian politicians. In this article the idea of replacing the old gas turbines of Polkalleh natural gas compressor station - as one of the main compressor stations of Iran - with newer and more efficient gas turbines is evaluated, emphatically for reducing greenhouse gases emissions and their environmental costs and decreasing natural gas consumption as well. Clearly such idea is costly, but analyzing its economic impacts, huge declines in annual costs and greenhouse gases emissions can be seen as well. So an investment about $95 million can decrease 40% of Polkalleh compressor station annual costs, 25% of natural consumption and 30% of $CO_2$ and $NO_x$ emissions. Besides the simple payback period of this investment is about 2.5 years from the cut-expenses of annual costs.

A Study on Life Cycle Cost on Railway Locomotive Systems

  • Egamberdiev, Bunyod;Lee, Kookchan;Lee, Jongwoo;Burnashev, Shamil
    • International Journal of Railway
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    • v.9 no.1
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    • pp.10-14
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    • 2016
  • Life cycle cost analysis is compulsively required for the system operation. System operation costs are consisted of acquisition, operation, maintenance and so on. In the beginning of the system planning, we need to take into account of various costs following the system operating. To implement LCC, we need to analyze system life cycle to identify all costs during system life. The costs can be divided into three parts. The first part is purchasing cost, the second for operating cost and the last for disposal cost. The second operating cost can be decomposed of operating cost included labor, energy consumption cost for system running, maintenance costs to keep systems healthy, delay cost caused from maintenance and hazard cost, and so on. In this paper, we carried out for railway locomotives which operate over more 30years and which cost about 10 million USD. We decompose the life cycle of the locomotives and break down the locomotives into subsystems to require maintenance or not, and subsystems to need energy or not. We showed how to decide optimal locomotives through cost identification and system breakdown.

A Study on the Energy Consumption of Elementary Schools in Daejeon Metropolitan City (대전광역시 초등학교의 에너지 사용에 관한 조사연구)

  • Lee, Sang Hyeok;Park, Seung Ik
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.14 no.1
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    • pp.8-15
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    • 2018
  • The purpose of this study was to analyze the energy consumption according to the HVAC systems in 122 elementary schools. To do this, we classified schools according to the HVAC systems. Selected schools were classified to the following groups by the HVAC equipments: EHP, EHP and GHP together and GHP. In addition we divided schools by the number of classes. The main results are as follow: 1) Annual average energy consumption at schools was about 300~900(kWh/students), $30{\sim}50(kWh/m^2)$, 9,000~29,000((kWh/class) 2) The smaller schools, the higher the energy consumption per class; energy usage of 10~19 classes's schools were approximately 3 times higher than 40 classes's schools. 3) Schools where the EHP was installed had the lowest energy costs and energy usage. The difference in energy costs was lower than the difference in energy usage because of the fuel price and the ratio of energy sources.

Economic Analysis of a Residential Ground-Source Heat Pump System (단독주택용 지열원 열펌프 시스템의 경제성 분석)

  • Sohn, Byong-Hu;Kang, Shin-Hyung;Lim, Hyo-Jae
    • New & Renewable Energy
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    • v.3 no.4
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    • pp.31-37
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    • 2007
  • Because of their low operating and maintaining costs, ground-source heat pump(GSHP) systems are an increasingly popular choice for providing heating, cooling and water heating to public and commercial buildings. Despite these advantages and the growing awareness, GSHP systems to residential sectors have not been adopted in Korea until recently. A feasibility study of a residential GSHP system was therefore conducted using the traditional life cycle cost(LCC) analysis within the current electricity price framework and potential scenarios of that framework. As a result, when the current residential electricity costs for running the GSHP system are applied, the GSHP system has weak competitiveness to conventional HV AC systems considered. However, when the operating costs are calculated in the modified price frameworks of electricity, the residential GSHP system has the lower LCC than the existing cooling and heating equipments. The calculation results also show that the residential GSHP system has lower annual prime energy consumption and total pollutant emissions than the alternative HVAC systems considered in this work.

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Energy Efficiency & Sustainability the Cleanliness Management Role of Components and System in Automotive and Hydraulics

  • Hong, J.H.;Day, Mike
    • Journal of Drive and Control
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    • v.9 no.4
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    • pp.19-25
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    • 2012
  • This paper explains how eliminating contamination from the manufacturing processes will lead to better product quality and hence the need for reworking, a trouble free commissioning period and greatly improved production efficiency. All of these will reduce costs and energy usage. It will also ensure that the product is delivered to the customer in a condition that will ensure improved reliability and longer life, again reducing both energy and other operating costs. Correctly designing the contamination control measures will achieve and maintain the level of fluid cleanliness that is required by the end user. The filter is critical to cleanliness management and should be selected with the same degree of thought and consideration as for other major components. This paper explains the role that Cleanliness Management plays in the reducing the carbon footprint of systems and processes by making them perform more efficiently for longer periods. It also examines two differing ways of selecting filters to incorporate the features of newer designs, and shows how significant savings in the costs of ownership can be achieved using these approaches.

Analysis of Costs for a Hydrogen Refueling Station in Korea (한국 수소 충전소 건설의 경제성 분석)

  • KANG, BYOUNGWOO;KIM, TAEHYUN;LEE, TAECKHONG
    • Journal of Hydrogen and New Energy
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    • v.27 no.3
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    • pp.256-263
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    • 2016
  • As the hydrogen era comes near future, hydrogen fuel cell vehicles are core of hydrogen economy. Until now, Korea has 17 hydrogen refueling stations but 9 hydrogen refueling stations have been retired already and 8 hydrogen refueling stations are still running. With a limited number of hydrogen refueling stations, it is very difficult to get scientific data for the economy of hydrogen refueling stations in Korea. Thus, based on NREL(National Renewable Energy Laboratory) study, we analyzed most recent data for the construction of hydrogen refueling stations in one specific site in Korea. The cost comparison data between Korea and USA shows 14% difference, saying higher costs of Korea. Korea looks 5 years delay compared to USA. This data will be an important tool for the investment from every industrial parties.

Safety Stock Management Framework for Semiconductor Enterprises Under Demand and Lead Time Uncertainties (반도체부품 수요 및 납기 불확실성을 고려한 안전재고 설정 프레임워크)

  • Ho-Sin Hwang;Su-Yeong Kim;Jin-Woo Oh;Se-Jin Jung;In-Beom Park
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.2
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    • pp.104-111
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    • 2023
  • The semiconductor industry, which relies on global supply chains, has recently been facing longer lead time for material procurement due to supply chain uncertainties. Moreover, since increasing customer satisfaction and reducing inventory costs are in a trade-off relationship, it is challenging to determine the appropriate safety stock level under demand and lead time uncertainties. In this paper, we propose a framework for determining safety stock levels by utilizing the optimization method to determine the optimal safety stock level. Additionally, we employ a linear regression method to analyze customer satisfaction scores and inventory costs based on variations in lead time and demand. To verify the effectiveness of the proposed framework, we compared safety stock levels obtained by the regression equations with those of the conventional method. The numerical experiments demonstrated that the proposed method successfully reduces inventory costs while maintaining the same level of customer satisfaction when lead time increases.

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Latest greenhouse product industry in Japan and newest computational techniques for aerodynamics in greenhouses

  • Lee, In-Bok
    • Proceedings of the Korean Society for Bio-Environment Control Conference
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    • 2000.10b
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    • pp.3-16
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    • 2000
  • Protection agriculture is the essential choice for human to increase the efficiency of limited crop production area under harsh and changeable weather boundary conditions, extend growing season, maximize the crop yields, and then increase the sustainable income of the grower. The investment costs far greenhouses as well as labor and energy costs are much higher than for conventional plant production systems, so these can only be balanced by better crop yields, higher labor productivity, and higher energy efficiency. (omitted)

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