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Oh S.-D.,Blue Economy Strategy Institute | Yoo Y.,Chung - Ang University | Song J.,Seoul National University | Song S.J.,Seoul National University | And 3 more authors.
Energy and Buildings | Year: 2014

Public buildings in Korea have an obligation to supply 10% of the total energy consumption from new and renewable energy sources, which requires proper tools for installation of the energy systems. In this study, a cost-effective method for integration of existing grids with new and renewable energy sources in public buildings in Korea is suggested. A key factor of the method is based on the fact that the unit costs of the products from the energy systems depends on the capacity factor or the utilization factor which is crucially dependent on the interaction between the energy demand pattern for the building and the production time of the specific energy from the new and renewable energy sources. For several public buildings such as two business buildings located at quite different weather conditions, a welfare center and a fire station at different locations, the proper combination of new and renewable energy sources is suggested by detailed numerical calculation based on the hourly energy demand pattern data obtained from field studies for the buildings to minimize the additional cost by installing the energy systems. © 2014 Elsevier B.V. All rights reserved. Source


Oh S.-D.,Blue Economy Strategy Institute | Kim K.-Y.,Samsung | Oh S.-B.,Ajou University | Kwak H.-Y.,Chung - Ang University
Applied Energy | Year: 2012

Fuel-cell-based cogeneration systems are very attractive because of their high electrical efficiency and low emissions of air pollutants. The polymer electrode membrane fuel cell (PEMFC) is especially appropriate for distributed power generation applications because it can be operated at relatively low temperatures and the system is less sensitive to the CO2 produced during the fuel reforming process. In this study, the optimal operating condition were determined for a 1-kW PEMFC-based combined heat and power (CHP) system based on the daily electricity and heat demand patterns for an apartment house in Korea, whose average monthly electricity and heat demands are 472kWh and 1312kWh, respectively. In addition, the unit cost of electricity was estimated using a thermoeconomic analysis and the economic gain achieved by introducing the PEMFC-based CHP system in the apartment house was calculated. Approximately 20% savings can be achieved in the operational cost of the PEMFC-based CHP system, if the installation cost is supported by the government. © 2012 Elsevier Ltd. Source


Song J.,Seoul National University | Song S.J.,Seoul National University | Oh S.-D.,Blue Economy Strategy Institute | Yoo Y.,Chung - Ang University
Renewable Energy | Year: 2015

The developers of new buildings in South Korea are going to have a renewable heat obligation to meet some proportion of heating & cooling demand with renewable heat sources such as ground-source heat pumps, biomass wood pellet boilers and solar water heating panels from 2016. This study evaluated the potential fossil fuel conservation by implementation of the renewable heat obligation in Korea, based energy demand patterns of the target buildings and cost and performance of the renewable heat sources. Results show that most of the developers of new buildings will adopt a ground-source heat pump because of long lifespan and low variable cost under the current electricity tariff. Ground-source heat pumps consume electric power generated from fossil fuel as the major source for operation while solar and biomass do not. This implies that under the current plan the percentage of potential decrease of fossil fuel use will be much lower than the percentage of heating & cooling demand met by renewable heat sources. Reclassifying ground-source heat pumps as highly energy efficient conventional heat sources rather than renewable heat sources, as the International Energy Agency does, would correct this undesired outcome and is suggested as a policy correction. © 2014 Elsevier Ltd. Source


Kim J.,Blue Economy Strategy Institute | Nam Y.,Pusan National University
Energies | Year: 2016

Groundwater heat pumps have energy saving potential where the groundwater resources are sufficient. System Coefficients of Performance (COPs) are measurements of performance of groundwater heat pump systems. In this study, the head and power of submersible pumps, heat pump units, piping, and heat exchangers are expressed as polynomial equations, and these equations are solved numerically to determine the system performance. Regression analysis is used to find the coefficients of the polynomial equations from a catalog of performance data. The cooling and heating capacities of water-to-water heat pumps are determined using Energy Plus. Results show that system performance drops as the water level drops, and the lowest flow rates generally achieve the highest system performance. The system COPs are used to compare the system performance of various system configurations. The groundwater pumping level and temperature provide the greatest effects on the system performance of groundwater heat pumps along with the submersible pumps and heat exchangers. The effects of groundwater pumping levels, groundwater temperatures, and the heat transfer coefficient in heat exchanger on the system performance are given and compared. This analysis needs to be included in the design process of groundwater heat pump systems, possibly with analysis tools that include a wide range of performance data. © 2015 by the authors. Source


Kwak H.-Y.,Chung - Ang University | You Y.,Blue Economy Strategy Institute | Oh S.-D.,Blue Economy Strategy Institute | Jang H.-N.,Korea Energy Management Corporation
International Journal of Energy Research | Year: 2014

A thermoeconomic analysis of a ground-source heat pump (GSHP) system with a vertical or horizontal ground heat exchanger, a type of heat delivery system, was performed using the modified productive structure analysis method. In this analysis, the unit cost of geothermal heat delivered to a room using GSHP system was estimated. The unit cost of heat delivered was calculated to be $0.063/kWh for input of electricity with a unit cost of $0.140/kWh for a GSHP with a coefficient of performance (COP) of 3.27. Exergy destruction and monetary losses due to the irreversibility that occurs at each component of the system were also estimated. The unit cost of heat was found to be inversely proportional to the COP of the heat pump and proportional to the electricity input. The greatest monetary loss occurs in the geothermal heat exchanger in which considerable mass of brine flows in long pipes and in the fan-coil unit which features a complex configuration of pipes in the air passages, respectively. © 2013 John Wiley & Sons, Ltd. Source

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