• 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.

• Journal of the Korean Solar Energy Society
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• v.38 no.4
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• pp.55-66
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• 2018

nZEH (net-Zero Energy House) is defined as a self-sufficient energy building where the sum of energy output generated from new & renewable energy system and annual energy consumption is zero. The electricity generated by new & renewable energy system with the form of distributed generation is preferentially supplied to electrical demand, and surplus electricity is transmitted back to grid. Due to the recent expansion of houses with photovoltaic system and the nZEH mandatory by 2025, the rapid increase of distributed generation is expected. Which means, we must prepare for an electricity-power accident and stable electricity supply. Also electricity charges have to be reduce and the grid-connected should be operated efficiently. The introduction of ESS is suggested as a solution, so the analysis of the load matching and grid interaction is required to optimize ESS design. This study analyzed the load matching and grid interaction by expected consumption behavior using actual data measured in one-minute intervals. The experiment was conducted in three nZEH with photovoltaic system, called all-electric houses. LCF (Load Cover Factor), SCF (Supply Cover Factor) and $f_{grid}$ (Grid Interaction Index) were evaluated as an analysis indicator. As a result, LCF, SCF and $f_{grid}$ of A house were 0.25, 0.23 and 0.27 respectively; That of B house were 0.23, 0.23, 0.19, and that of C were 0.20, 0.19, 0.27 respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.238.2-238.2
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• 2010

Recently, environmental pollution and energy depletion problems have been issued over the world. For this reason, many renewable systems have been developing. Of these, the Ocean Thermal Energy Conservation(OTEC) is drawing attention as the upcoming alternative energy source. In this paper, the efficiency of each of OTEC which harness the effluent from nuclear power plant was analyzed by using computer calculation. The result, shows that Ul-jin Nuclear Power Plant is the best place geographically and the regenerative cycle is most outstanding performance cycle for OTEC. The difference of temperature between surface water and deep water temperature should be greater than $20^{\circ}C$ in order to increase the efficiency.

• New & Renewable Energy
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• v.9 no.1
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• pp.17-24
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• 2013

Eddy Current is one of ways to make heat using rotational energy of wind turbine rotor. Four difference arrays of permanent magnets around rotor surface are used to generate heat using eddy current in this study. For the evaluation of heating performance, new test rig is prepared to measure water flow and temperatures in the inlet and outlet of the eddy current heat generator. In the test, torque and rotational speed are also measured in the motor driven system, and evaluated if the torque is matched with it of wind turbine rotor or not. It will be shown that the eddy current heat generator can be applied to real urban wind energy systems in this study.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.608-609
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• 2008

Photovoltaics and wind energy sources are being increased recognised as cost effective generation sources in small isolated power systems(SIPS) primarily supplied by costly diesel fuel. Deterministic and probabilistic techniques are combined using a system well-being approach to provide useful reliability indices for SIPS containing renewable energy. An evaluation of the contribution from photovoltaics and wind energy sources to SIPS reliability is presented. The practicality and effectiveness of the methodology is illustrated by a case study.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.439-442
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• 2009

As a result of increasing environmental concern, the penetration of renewable power on power systems is now increasing. Wind energy can be considered as the most economical energy sources to generate electricity without depletion of fossil fuel. The penetration of wind energy from wind farm is getting larger and larger, so we need adequate control strategies for wind farm. To devise adequate control strategies for wind farm, time domain simulation analysis needs to be performed. This presents a Simultaneous Implicit-based time domain simulation algorithm for wind farm with DFAG (Doubly Fed Asynchronous generator) connected to the external power systems. This paper shows an illustrative example with a 5-bus test system.

• New & Renewable Energy
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• v.10 no.1
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• pp.41-49
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• 2014

For a proper valuation of wind power project, it is necessary to consider volatilities of key parameters such as annual energy production, electricity sales price, and long term interest rate. Real option methodology allows to calculate option values of these parameters. Volatilities to be considered in wind project valuation are 1) annual energy production (AEP) estimation due to meteorological variation and estimation errors in wind speed distribution, 2) changes in system marginal price (SMP), and 3) interest rate fluctuation of project financing which provides refinancing option to be exercised during a loan tenor for commercial scale projects. Real option valuation turns out to be more than half of the sales value based on a case study for a FIT scheme wind project that was sold to a financial investor.

• New & Renewable Energy
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• v.20 no.2
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• pp.2-16
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• 2024

Various loads induced by marine environmental conditions, such as waves, currents, and wind, are crucial for the operation and viability of offshore wind power (OWP) systems. In particular, waves have a significant impact on the stress and fatigue load of offshore structures, and highly reliable design parameters should be derived through extreme value analysis (EVA) techniques. In this study, extreme wave analyses were conducted with various Weibull distribution models to determine the reliable design parameters of an OWP system suitable for the Ulsan area. Forty-three years of long-term hindcast data generated by a numerical wave model were adopted as the analyses data, and the least-squares method was used to estimate the parameters of the distribution function for EVA. The inverse first-order reliability method was employed as the EVA technique. The obtained results were compared among themselves under the assumption that the marginal probability distributions were 2p, 3p, and exponentiated Weibull distributions.

• New & Renewable Energy
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• v.20 no.2
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• pp.55-64
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• 2024

To ensure the frequency stability of wind power generation, we analyzedd the existing technology and proposedd a method for changing the gain value with respect to to the rotor speed by adding the MPPT reference value and output reference value that reflect the system frequency. The MPPT control and output were compared and calculated for performance verification. Subsequently, the application of the proposed algorithm led to an increased output when compared with that of the existing control method.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.1
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• pp.7-13
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• 2014

This study intends to analyse the economical aspect of a GSHP(Ground Source Heat Pump) system compared to the conventional system which is consisted with a boiler and a chiller. This study has simulated four systems in Incheon. It developed and analyzed for applications in a residential and an office building which was based on the hourly EPI(Energy Performance Index, $kWh/m^2yr$). Case 1 is utilizing a boiler and a chiller to meet heating and cooling demand of a house. Case 2 is utilizing the same conventional set up as Case 1 of a office. Case 3 is summation of Case 1(house) and 2(office) systems and loads. And Case 4 is utilizing a GSHP to meet the combined loads of the house and office. The method of the economic assessment has been based on IEA ECBCS Annex 54 Subtask-C SPB(Simple Payback) method. The SPB calculated the economic balanced year of the alternative system over the reference system. The SPB of the alternative systems (GSHP) with 10%, 30% and 50% initial incentive has been calculated as 9.38, 6.72 and 4.06 year respectively while the SPB without initial incentive of systems was 10.71 year.