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1、Economic assessment of geothermal district heating systems:A case study of BalcovaNarlidere, TurkeyBerkan Erdogmus a, Macit Toksoy a, Baris Ozerdem a,*, Niyazi Aksoy b a Department of Mechanical Engineering, Faculty of Engineering, Izmir Institute of Technology, Urla 35430, Izmir, Turkey b Torbali V
2、ocational School, Dokuz Eylul University, Izmir, Turkey Received 17 November 2005; received in revised form 27 December 2005; accepted 2 January 2006Abstract Geothermal energy is an important renewable energy resource in Turkey. The aim of this research is to evaluate the BalcovaNarlidere geothermal
3、 district heating system from an economic perspective. The system is the largest one in Turkey in terms of heating capacity and located in Izmir. Although there are some assessments regarding energy and exergy analysis for the BalcovaNarlidere geothermal district heating system, an economic assessme
4、nt was not performed, previously. The profitability of the investment is investigated by using internal rate of return method. Seven hundred and eighty different scenarios are developed in this assessment. In order to estimate the potential cash flows in the remaining project life, operating cost in
5、 2002 is decreased and increased, alternatively, between 5% and 30% by 5% in each step, while monthly energy utilization price is changed between US$ 17 and 72 in those scenarios. The energy utilization prices are suggested according to zero IRR value for all scenarios due to the consideration of so
6、cial and environmental concerns in this investment. It is found that, the proper monthly energy utilization price for a 100 m2 household would be US$ 55.5 when the operating cost and heating capacity in 2002 were remained constant. Keywords: Geothermal district heating; Internal rate of return; Econ
7、omic assessment1. Introduction Geothermal energy is recognized as one of the significant renewable energy resources to meet increasing energy demand of the world. Systems, using geothermal energy, are made up of three main elements: a heat source, a reservoir, and a fluid 1. In geothermal systems, h
8、eat is recovered from hot subsurface formations with the help of meteoric water, which circulates down through the fractures and pores in the rocks. It absorbs the heat and returns to the surface with elevated temperature. Geothermal energy utilization applications have been recently subject to grow
9、ing attention because of their minimum negative environmental impact, low operating cost, decentralized production advantages, and simplicity of their technologies. Geothermal energy utilization can be categorized in two groups with regard to the temperature of geothermal resources: electricity gene
10、ration and direct use 2. Space heating, domestic water heating, greenhouse heating, CO2 and dry ice production, and balneological use of geothermal fluids are the well-known direct use applications 3. In general, lower geothermal fluid temperatures are required for direct use. Geothermal resources h
11、aving fluid temperatures between 90 and 150 8C are suitable for district heating in which heat is distributed to a large number of individual houses or blocks of buildings from a central location, through a network of pipes 4,5. Geothermal resources having fluid temperatures above 150 8C are mainly
12、used to generate electricity. Turkey is poor in fossil fuel resources but rich in renewable resources such as geothermal, solar, biomass, wind, and hydraulics. The wide spread volcanism and femoral hydrothermal alterations indicate significant existence of geothermal resources in Turkey. One hundred
13、 and seventy geothermal fields and about one thousand thermal and mineralwater springs with a temperature range of 40242 8C have been discovered in Turkey which is located on Mediterranean sector of Alpine-Himalaya belt 6. This land is very active with earth crust movements, tectonic movements of th
14、e rock formations, and volcanic activities 7,8. According to the resource assessment, which has been done by the Mineral Research and Exploration Directorate of Turkey, the geothermal resources in the country are mostly moderate and low- temperatured ones and located in the North Anatolia fault zone
15、, whereas, high enthalpy fields are located on the graben structure of western Anatolia.At the moment, there are 38 geothermal space-heating systems in Turkey. However, only eleven of them are city based geothermal district heating systems. The total capacity of eleven city based geothermal district
16、 heating systems is calculated as 253.1 MW by using suggested method for energy production network 9. Table 1 shows city based geothermal district heating systems with their current mass flow rates, inlet and outlet temperatures of geothermal fluid in primary heat exchangers. As it is seen from Table 1, BalcovaNarlidere geothermal district heating system is the largest one in Turkey.In this research, it is investigated whether the Ba
