Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Subject: search.filters.subject.Geothermal power plants

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  • Master Thesis
    Kinetics of Silica Polymerization at Various Conditions
    (01. Izmir Institute of Technology, 2022) Baba, Alper; Demir, Mustafa Muammer; Demir, Mustafa Muammer; Baba, Alper; 03.03. Department of Civil Engineering; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Silica is the most abundant element on Earth because the Earth's crust is composed mainly of metal silicates. The source of this silica is mainly volcanic rocks, which come to the surface through tectonic activity and are the primary source of heat for geothermal activity. The silica concentration in a geothermal fluid is higher than the solubility limit of natural waters, so scaling of (metal) silicates is often observed in geothermal operations. This situation has become critical for geothermal power plants. Since silicates have an insulating structure, they lead to a reduction in energy efficiency during fluid transport. The formation of silica-rich deposits should be understood to minimize the negative effects of the scaling. Briefly, silicic acid molecules in the reservoir system are condensed, and the monomeric silicic acid molecules bind to each other via covalent bonds. In the course of this reaction, dimers, tetramers and short oligomers are formed, and eventually a large polymeric silica network is formed. In the presence of metals, both the kinetics of polymerization and the structure of the network are inevitably affected. In this study, the presence of kinetic parameters (different salts such as FeCl3, MgCl2, AlCl3 and NaCl), the reaction process, the rate and the activation energy of silica polymerization at different temperatures between 25 and 90 °C were investigated. The yellow silicomolybdate method was used to determine the concentration of monomeric silica. The order of the polymerization reaction was given as 3. The polymerization occurs in the initial phase, in the first 40 minutes, where the activation energy was about 29.52 ± 2.28 kJ/mol and the rate constant was of the order of 4x10-8 mol-2∙L2∙s-1. The results also confirmed that pH has a stronger effect on the kinetics of silica polymerization than temperature. The neutral solution decreases rapidly, while the acidic solution has an induction phase in the first hour of polymerization. Different temperatures did not affect the polymerization rate as much as pH. At 25°C the experiment showed the fastest polymerization, but at 90°C the low concentration changed from the beginning. During all these experiments, no scaling of amorphous silica was observed, only the polymerization of silica.
  • Master Thesis
    Evaluating the Impacts of Geothermal Energy Plants on Quality of Life: Case of Alasehir (manisa)
    (01. Izmir Institute of Technology, 2021) Velibeyoğlu, Koray; Velibeyoğlu, Koray; 02.03. Department of City and Regional Planning; 02. Faculty of Architecture; 01. Izmir Institute of Technology
    Quality of life has been handled with different approaches by many disciplines from past to present, and it has started to be used frequently in the international agenda in order to meet the needs of the increasing world population and to find solutions to problems such as climate change. Due to the multidimensional and complex nature of the concept, there is no consensus on the definition and measurement method. Quality of life definitions, and indicators varies in the context of scale, approach, and method. The study concentrates on the perceived quality of life of people close proximity to geothermal power plants in the case of Alaşehir. First, the indicators used in neighbourhood, rural and environmental quality of life studies were examined and grouped under the parameters of built environment, accessibility, vulnerability, degradation, health, contamination, and resilience. Then, the historical background, usage, geothermal systems, environmental impacts and social acceptance of geothermal energy and geothermal energy studies in Turkey were evaluated. As a result of this evaluation, the participation parameter was added to the research. In line with socio-spatial analysis, the areas under the influence of geothermal power plants were determined and semi-structured interviews were conducted with the parameters. As a result of the analyses and interviews, it has been determined that the impact of geothermal energy on the quality of life in Alaşehir district is perceived through agricultural production. Contamination, vulnerability, and participation parameters come to the fore, and show that geothermal power plants negatively affect the perceived quality of life.
  • Master Thesis
    A Case Study on Settlement Analysis of Geothermal Power Plant Foundation
    (01. Izmir Institute of Technology, 2018) Elmas, Hakan; Elmas, Hakan; Ecemiş Zeren, Nurhan; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Foundation settlement criteria are highly sensisitive for geothermal power plants. In geotechnical literature there are several settlement analyses which can be done by using elastic approaches, in-situ test results or numerical methods. Unfortunately, all these methods cannot give close results with each other. As a result, the unrepresentative analyses influence the safety, economy and time of the projects. In this study, the settlement of the geothermal power plant located in Aydın / İncirliova which constructed on a raft foundation was investigated. According to soil investigations, the raft foundation is located on multilayer soil profile and a compacted high qualified fill layer is placed under the raft foundation. Soil parameters were obtained from in-situ tests (standard penetration tests, cone penetration tests, pressuremeter tests and plate load test and) and laboratory experiments. Settlement results were obtained by 1D stress – strain analyses and 3D continuum numerical analyses (Hardening Soil Model with Small Strain Stiffness and Mohr Coulomb Soil Model) using the commercially available Settle 3D and Plaxis 3D software, respectively. The results of these analysis were also compared with the field monitoring data. The results show that Hardening Soil Model with Small Strain Stiffness gave more accurate result than other models due to the representation of real soil behavior, obtaining non-uniform stress distribution of foundation and obtaining effective stress depth accurately for settlement.
  • Master Thesis
    Thermodynamic Optimization of Downhole Heat Exchangers for Geothermal Power Generation
    (Izmir Institute of Technology, 2016) Parmanto, Slamet; Gökçen Akkurt, Gülden; Yıldırım, Nurdan; Gökçen Akkurt, Gülden; Yıldırım Özcan, Nurdan; 03.10. Department of Mechanical Engineering; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Geothermal reservoirs have various thermodynamic and physical properties. The heat extraction and power generation from the geothermal reservoirs depend on the reservoir properties. Downhole heat exchangers (DHEs) are designed to move the heat extraction process into the geothermal well. The working fluid is injected to the DHE which suspends in the geothermal well, heated by geothermal fluid and then returned to the surface through the inner pipe. DHEs have been used for heating purposes widely but there is no application for electricity generation. Because of the natural convection on the geothermal fluid side, convective heat transfer coefficient is low and simultaneously the heat extraction rate is low comparing with extracting geothermal fluid by downhole pumps. Therefore if the temperature is high but flowrate is low in a geothermal well, DHEs are good alternatives to harness the energy from that well. Considering the number of wells with abovementioned conditions in the World, there is a potential for electricity generation coupling geothermal power plants with DHEs. The main purpose of the Thesis is to develop a thermodynamic and economic evaluation model of DHEs for power generation and to examine the feasibility of the model. The thermodynamic model is developed by EES software and over 300 simulations have been conducted to identify the effects of the insulation, geothermal well conditions, geometry of DHE, mass flowrate and the type of working fluids to the performance of DHE system. The economic analyses are conducted to evaluate the thermodynamic results regarding the economic consideration such as Net Present Value (NPV), simple payback time and electricity production rate. The results show that the insulation on the inner pipe is desirable to prevent heat loss along DHEs. The best design of the DHE is a design with deeper the depth, larger the diameter of the inner pipe, and higher mass flowrate for a specific geothermal heat source. The best design for the case study resulted as a work output of 3152 kW with annual net revenue and payback time of $1.75 million and 2.24 years, respectively. Besides, the economic evaluation gives positive value for NPV which means investment in DHE for geothermal power generation is acceptable.
  • Master Thesis
    Performance Assessment of a Binary Cycle Geothermal Power Plant
    (Izmir Institute of Technology, 2013) Karadaş, Murat; Çelik, Hüseyin Murat; Çelik, Hüseyin Murat; 02.03. Department of City and Regional Planning; 02. Faculty of Architecture; 01. Izmir Institute of Technology
    An air cooled binary cycle GPP is thermodynamically modeled by using the design data of an actual plant. Effects of design parameters are investigated to plant performance. The modeling binary cycle power plant is produced 6514 kWe by using 542.65 ton/hour brine, 22.45 ton/hour steam and 33.4% NCGs content of steam at 157.9 °C geothermal resource temperature and 17.1 °C average ambient air conditions. The thermal efficiency of the model plant is found 11.32 %. The performance equations and the theoretical net power correction factors of the plant are created by using the thermodynamic model. According to this model, the net power generation of the plant increases with an increase in brine temperature, and mass flow rates of brine and steam; decreases with an increase of ambient air temperature and NCGs content of the steam. Furthermore, regression analysis of DORA-1 GPP is conducted using actual plant data to assess the plant performance. The annual multiple linear regression models are developed from 2006 to 2012 to estimate the performance of a geothermal power plant by using three measured dependent variables: the ambient air temperature, the brine flow rate and temperature. These models are tested by using classical assumptions of linear regressions, positive serial autocorrelation is found in all models. Autocorrelations are eliminated by using Orcutt-Cochran method. Although the performance model trends from 2006 to 2008 are found to be close, the performance status of the plant is generally variable from year to year. According to perennial regression models, the plant performance has started to decline with 270 kWe electricity generation capacity since 2009. The total degradation of the plant performance reached to 760 kWe capacity by 2012. Additionally, the statistical net power correction factors are calculated using regression model of 2008. Consequently, the net power correction factors for thermodynamic model and regression analysis are compared with DORA-1’s manufacturer, Ormat, correction factors. Although there are some minor differences, all of the net power correction factors have similar trends. The comparison shows that Ormat’s correction factors don’t exactly express the performance status of the DORA-1 GPP.
  • Master Thesis
    Financial Evaluation Of Kızıldere Geothermal Power Plant
    (Izmir Institute of Technology, 2010) Konyalı, Ayşe; Özkol, Ünver; Özkol, Ünver; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    A capacity increase is of concern in the Kızıldere Geothermal Power Plant-the first geothermal plant in Turkey. In this study, the feasibility of possible future investments in Kızıldere has been analyzed financially using methods such as internal rate of return, net present value, payback and benefit-cost. Two scenarios with different financial structures have been formed and both scenarios have been applied to 20MW, 40 MW, and 60 MW power plants. The choice among different alternatives has been made according to the unit energy cost, which is a significant parameter in power plants. The first scenario represents a government project which establishes the project finance on a debt ratio of 75%. The debt term has been taken as 12 years and the debt interest rate as 7%. In this scenario, unit energy cost has been estimated as 4,33 cent/kWh for 20 MW, 4,10 cent/kWh for 40 MW and finally 3,88 cent/kwh for 60 MW. The second scenario represents a private project with a debt ratio of 50%, where the debt term is 8 years and the debt interest rate is taken as 5%. As for the unit energy cost for this particular scenario, it has been estimated as 3.8 cent/ kWh, 3.59 cent/kWh and 3.40 cent/kWh for 20 MW, 40 MW and 60 MW respectively. Kızıldere geothermal Plant has been financially evaluated in this study and it has been concluded that although both scenarios are feasible, the best alternative is 60MW private project.