• 한국신재생에너지학회:학술대회논문집
• /
• 2006.11a
• /
• pp.20-23
• /
• 2006

Geothermal energy is the natural heat of the Earth. Enormous amounts of thermal energy are continuously generated by the decay of radioactive isotopes of underground rocks and stored in the Earth's interior. Therefore, geothermal energy is one of the most important sustainable energy resources. Recent trends of geothermal energy exploitation technologies focus on the Earth scientific approach to geothermal heat pump system, enhanced geothermal system, aquifer thermal energy storage, underground thermal energy storage, and fluid/heat flow model ing for geothermal wells. Geothermal heat pump distribution in Korea is still in its starting phase in terms of areal utilization sense, we, however, expect to come up with national supply of over 1,000,000 toe by 2020

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.782-787
• /
• 2008

The Kalina cycle simulation study was carried out for a preliminary design of a geothermal power generation system. The Kalina cycle system can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency, while a condenser, an evaporator and a regenerative heat exchanger were modeled by UA-LMTD method with a counter-flow assumption. The simulation results show that the power generation efficiency over 10% is expected when a heat source and sink inlet temperatures are $100^{\circ}C$ and $10^{\circ}C$ respectively.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.3 no.2
• /
• pp.17-23
• /
• 2007

Geothermal energy is used in various forms, such as power generation, direct use, and geothermal heat pumps. High temperature geothermal energy sources have been used for power generation for more than a century. Recent technical advances in power generation equipments make relatively low temperature geothermal energy to be available for power generation. In these applications, lower temperature geothermal energy source makes smaller difference between condensing water temperature and it. Various condensing water temperatures were investigated in analyzing its influence on power generation performance. Condensing water temperature of organic Rankine cycle imposed greater influence on power generation and its performance in lower temperature geothermal power generation.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.5 no.2
• /
• pp.13-19
• /
• 2009

This study describes energy and exergy analysis of the Maeeum-Ri Geothermal District Heating System(MGDHS) of Ganghwa Island, Incheon, Korea. Design data are used to assess the performance of the geothermal district heating system. Geothermal resources of MGDHS are found to be low quality with specific exergy index of 0.029. Exergy losses occur in the pumps and heat exchangers as well as in the geothermal Quid and direct discharge. As a result, the total exergy losses accounts for 5.2% in pumps, 47% in the discharge, and 3.3% in heat exchanger based on the total exergy input to the entire MGDHS. The overall energy and exergy efficiencies of the system are found to be 28.8% and 44.5%, respectively.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.7 no.2
• /
• pp.1-9
• /
• 2011

Geothermal heat pumps are known as the most efficient and environment-friendly heating and cooling system, and are also gaining acceptance in buildings. Building energy simulation program, EnergyPlus is used to calculate the energy consumption of residential buildings. This simulated energy consumption is essential for accurate economic analysis. Residential buildings with geothermal heat pumps have complex energy price structure. Electricity rates for residential buildings increase rapidly as the monthly use increases. This complex energy price structure makes the economic analysis complicated. The purpose of this study is to conduct economic comparison of residential geothermal heat pumps and provide a feasible approach in finding their economically feasible capacity.

• Journal of Hydrogen and New Energy
• /
• v.23 no.5
• /
• pp.551-558
• /
• 2012

Due to high oil prices and global warming problems, researching an alternative energy source and decreasing the energy usage will be the key in the future. Unlike other alternative energy sources, geothermal energy is less dependent on the surrounding environment. Geothermal energy is the ideal energy source for buildings due to the simple and space saving installation. The system is semi permanent once it is installed and this will help reduce the energy usage in controlling the climate in buildings. Geothermal energy does not emit carbon dioxide and other gases that are harmful to the environment. Therefore geothermal energy will be the key in solving high oil prices and a decrease in fossil fuels by applying the geothermal energy system to homes to counter future energy crisis.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.794-800
• /
• 2008

Due to high oil prices and global warming problems, researching an alternative energy source and decreasing the energy usage will be the key in the future. Unlike other alternative energy sources, geothermal energy is less dependent on the surrounding environment. Geothermal energy is the ideal energy source for buildings due to the simple and space saving installation. The system is semi permanent once it is installed and this will help reduce the energy usage in controlling the climate in buildings. Geothermal energy does not emit carbon dioxide and other gases that are harmful to the environment. Therefore geothermal energy will be the key in solving high oil prices and a decrease in fossil fuels by applying the geothermal energy system to detached house to counter future energy crisis.

• Journal of the Korean Solar Energy Society
• /
• v.33 no.5
• /
• pp.95-104
• /
• 2013

This study set out to devise an optimized system to take into account life cycle cost(LCC) and ton of carbon dioxide($TCO_2$) by applying the weighted coefficient method(WCM) to "public-purpose" facility buildings according to the mandatory 5% and 11% of new renewable energy in total construction costs and anticipated energy consumption, respectively, based on the changes of the public obligation system. (1) System installation capacity is applied within the same new renewable energy facility investment according to the mandatory 5% of new renewable energy in total construction costs. Both LCC and $TCO_2$ recorded in the descending order of geothermal, solar, and photovoltaic energy. The geothermal energy systems tended to exhibit an excellent performance with the increasing installation capacity percentage. (2) Optimal systems include the geothermal energy(100%) system in the category of single systems, the solar energy(12%)+geothermal energy(88%) system in the category of 2-combined systems, and the photovoltaic energy(12%)+solar energy(12%)+geothermal energy(76%) system and the photovoltaic energy(12%)+solar energy(25%)+geothermal energy(63%) system in the category of 3-combined systems. (3) LCC was the highest in the descending order of photovoltaic, geothermal and solar energy due to the influences of each energy source's correction coefficient according to the mandatory 11% of new renewable energy in anticipated energy consumption. The greater installation capacity percentage photovoltaic energy had, the more excellent tendency was observed. $TCO_2$ recorded in the descending order of geothermal, photovoltaic and solar energy with the decreasing installation capacity of photovoltaic energy. The greater installation capacity percentage a geothermal energy system had, the more excellent tendency it demonstrated. (4) Optimal systems include the geothermal energy(100%) system in the category of single systems, the photovoltaic energy(62%)+geothermal energy(38%) system in the category of 2-combined systems, and the photovoltaic energy(50%)+solar energy(12%)+geothermal energy(38%) system and the photovoltaic energy(12%)+solar energy(12%)+geothermal energy(76%) system in the category of 3-combined systems.

• Proceedings of the SAREK Conference
• /
• 2007.06a
• /
• pp.22-22
• /
• 2007

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.669-673
• /
• 2005

World geothermal resources potential is estimated to supply 189 EJ annually, which can take charge approximately a half of annual world energy consumpt ion, from considering identified resources and supplies in USA and Iceland. Present annual use of geothermal energy, on the other hand, is only $0.1\%$ of its potential, but still has $70\%$ share among total new renewables. World-wide installed capacity of geothermal power generation reaches 8,900 MWe and 27,825 MWt for direct uses in 2005 which is almost two-fold increase over 2000. This increase is mainly due to exploding expansion of geothermal heat pump utilization: USA and western European countries lead these trends. Although geothermal heat pump distribution in Korea is still in its starting phase, comparing to Swiss achievement in terms of areal utilization sense, we expect to come up with national supply of over 600,000 toe in near future.