Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
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Review Citation - WoS: 5Citation - Scopus: 5Geothermal Energy Potential in Relation To Black Carbon Reduction and Co2 Mitigation of Himalayan Geothermal Belt – a Review(Elsevier Ltd, 2024) Singh,H.K.; Chandrasekharam,D.; Raju,N.J.; Ranjan,S.We have compiled geochemical dataset of springs (Thermal and Cold) from the Himalayan Geothermal Belt (HGB), shows slightly acidic to moderately alkaline (pH = 4.5 – 9.4) in nature with an emerging surface temperature of 27 °C – 96 °C. The calculated reservoir temperature ranged in between 78 °C – 159 °C categorize the HGB as a low- to a moderate-enthalpy geothermal system. It was observed that geochemical facies of thermal springs dominated by the Ca-HCO3, Na-HCO3 and Na-Cl composition while cold springs are abundant in Ca-Mg-HCO3 and Ca-Mg-SO4. Interestingly, Piper diagram inferred that Puga, Chumathang, and Gaik thermal springs, lies in the western part of HGB that correlate with the Yangbajing thermal spring in Tibet (eastern part of HGB). Tectonically, the HGB is associated with the continental collision zone, shallow crustal melting, and high heat-producing younger granite (70 mW/m2 to > 400 mW/m2); therefore, the resultant geothermal gradient along the HGB is more than 200 °C/km. The present research documents that HGB have potential to reduce CO2 and BC emissions by taping the geothermal energy for power generation and we have projected that the power potential of HGB is 23,622 MWe that can help to mitigate 1.4 × 108 tCO2. © 2024 Elsevier LtdArticle Citation - WoS: 1Citation - Scopus: 1Energy and Exergy Analysis of a Geothermal Energy Sourced Hot-Air Drying System(Inderscience Enterprises, 2023) Helvacı, Hüseyin Utku; Keleş, Nazlı; Gökçen Akkurt, GüldenA geothermal energy-sourced drying system was tested for the thin-layer drying process of tomato slices at air temperatures of 40 degrees C, 50 degrees C and 60? and velocities of 0.5 m/s and 1.5 m/s to investigate system performance in terms of the first and second laws of thermodynamics. The energy and the exergy efficiency of the system were found to be 6.6% and 22.31%. The energy utilisation and energy utilisation ratio were calculated in the range of 1.271 kW-5.102 kW and 9.644%-39.56%, respectively. The exergy destruction, exergy efficiency and improvement potential of the drying chamber varied between 0.0198 kW-0.2621 kW, 59.74%-81.95% and 0.00486 kW-0.07396 kW, respectively.Article Citation - WoS: 40Citation - Scopus: 47Boron in Geothermal Energy: Sources, Environmental Impacts, and Management in Geothermal Fluid(Elsevier, 2022) Mott, A.; Baba, Alper; Hadi Mosleh, Mojgan; Ökten, Hatice Eser; Babaei, Masoud; Gören, Ayşegül Yağmur; Feng, C.; Recepoğlu, Yaşar Kemal; Uzelli, Taygun; Uytun, Hüseyin; Morata, Diego; Yüksel Özşen, AslıThe problem of hazardous chemicals in geothermal fluid is a critical environmental concern in geothermal energy developments. Boron is among the hazardous contaminants reported to be present at high concentrations in geothermal fluids in various countries. Poor management and inadequate treatment of geothermal fluids can release excessive boron to the environment that has toxic effects on plants, humans, and animals. Despite the importance of boron management in geothermal fluid, limited and fragmented resources exist that provide a comprehensive understanding of its sources, transport and fate, and the treatment strategies in geothermal energy context. This paper presents the first critical review from a systematic and comprehensive review on different aspects of boron in geothermal fluid including its generation, sources, toxicity, ranges and the management approaches and treatment technologies. Our research highlights the origin of boron in geothermal water to be mainly from historical water-rock interactions and magmatic intrusion. Excessive concentrations of boron in geothermal fluids have been reported (over 500 mg/L in some case studies). Our review indicated that possible boron contamination in geothermal sites are mostly due to flawed construction of production/re-injection wells and uncontrolled discharge of geothermal water to surface water. The dominancy of non-ionic H3BO3 species makes the selection of the suitable treatment method for geothermal waters limited. Combining boron selective resins and membrane technologies, hybrid systems have provided effluents suitable for irrigation. However, their high energy consumption and course structure of boron selective resins encourage further research to develop cost-effective and environmentally friendly alternatives.Article Citation - WoS: 8Citation - Scopus: 11Geothermal Potential of Granites: Case Study- Kaymaz and Sivrihisar (eskisehir Region) Western Anatolia(Elsevier, 2022) Chandrasekharam, Dornadula; Baba, Alper; Ayzit, Tolga; Singh, Hemant K.Radiogenic granites are gaining importance due to their ability to generate a substantial amount of electricity and support the advancement of agricultural and water sectors. In the western Anatolian region, such granites occupy a cumulative area of 6910 km2 varying from 7 to 20 μW/m3, far above the heat generated by the average continental crust of 5 μW/ m3. One cubic. The granite plutons of the Eskisehir region are amongst such granites with radioactive heat generation kilometer of such granite can generate 79 × 106 kWh of electricity. In the present case, the Eskisehir granites are capable of generating 616 million kWh of carbon-free electricity. Besides electricity, the heat from the granites can be utilized for space heating and greenhouse cultivation. This energy can also be utilized for the generation of fresh water from the sea through the desalination process. Hydrofracturing of the granites to create a fracture network connecting injection and production well is being replaced with closed-loop system that do not require knowledge about the stress pattern of the region and reduce the risk of induced micro-seismicity that was a bottleneck for developing EGS projects. Although the currently estimated cost of electricity generated from EGS projects is 9 euro cents/kWh, this cost will get reduced due to technological development in drilling technology. The Western Anatolian region has an additional advantage over the cost, since the drilling depth to capture the heat from the granites is shallow (∼3 km) which gives further benefit to the cost due to the reduction in drilling depth cost. In addition to high radiogenic granites, the presence of curie point temperature at shallow depth, high heat flow, and high geothermal gradient makes this region a warehouse of energy making Turkey energy-food and water independent in the future.Article Citation - WoS: 38Citation - Scopus: 40Exergoeconomic Analysis and Optimization of a High-Efficient Multi-Generation System Powered by Sabalan (savalan) Geothermal Power Plant Including Branched Gax Cycle and Electrolyzer Unit(Elsevier, 2022) Seiiedhoseiny, Miryasin; Khani, Leyla; Mohammadpourfard, Mousa; Gökçen Akkurt, GüldenEmploying suitable subsystems to reach high efficiency and low cost in renewable-based power plants is more crucial. The geothermal energy heat source is located in many countries, but this has never been investigated to run a multi-generation system, including a branched GAX cycle and an electrolyzer. In this path, a high-efficient multi-generation system powered by a Sabalan (Savalan) geothermal power plant consisting of a single flash cycle, a branched GAX cycle, and an electrolyzer is presented and scrutinized from thermodynamic and exergoeconomic viewpoints. In the end, a two-objective optimization, by using the Total Unit Cost of Product (TUCP) and energy efficiency as objectives, is utilized to find the optimum operating conditions. Critiques and studies of variables reveal that the produced hydrogen rate remains unchanged at 5.655 kg/h by changing the degassing value and temperature of the generator, condenser 2, and evaporator. By increasing the flash tank pressure from 5.2 bar to 7 bar, the cooling and heating loads rise about 108.4%, while the net electricity falls from 3977 kW to 3506 kW. Interestingly, the TUCP has a minimum value at the evaporator temperature of 273 K and condenser 2 temperature of 322.3 K. The optimization results indicate the values of the produced hydrogen rate and net electricity with 5.85 kg/h and 4187 kW are more than those of the base case. Also, the optimal values are 7.046 $/GJ, 36.82%, and 65.42% for the TUCP and energy and exergy efficiencies, respectively.Article Citation - WoS: 33Citation - Scopus: 42Thermodynamic Assessment of Downhole Heat Exchangers for Geothermal Power Generation(Elsevier, 2019) Yıldırım, Nurdan; Parmanto, Slamet; Akkurt, Gülden GökçenDownhole heat exchanger is a device to extract heat from geothermal fluid. While it is widely used for heating purposes, its use for power generation has not been reported. The aim of this study is to examine the feasibility of power generation from a 2500 m deep existing geothermal well with high temperature gradient and insufficient flowrate by using a downhole heat exchanger. For this purpose, a thermodynamic and an economic evaluation model are developed by the use of Engineering Equation Solver software. Additionally, the parametric studies have been carried out to identify the effects of insulation, geothermal well conditions, geometry of downhole heat exchanger, mass flowrate and type of working fluids on the performance of downhole heat exchanger system. Consequently, work output of the best alternative is computed as 2511 kW(e) with 64 kg/s mass flowrate of R-134a for 2500 m-deep downhole heat exchanger having inner pipe diameter of 0.127 m. Electricity generation cost and simple payback time are calculated as 46 $/MWh and 2.25 years, respectively. The obtained results showed that the downhole heat exchanger system can be a feasible alternative for wells with very low geothermal flowrate to generate power. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 13Citation - Scopus: 16The Injection of Co2 To Hypersaline Geothermal Brine: a Case Study for Tuzla Region(Elsevier Ltd., 2019) Topçu, Gökhan; Koç, Gonca A.; Baba, Alper; Demir, Mustafa MuammerScaling is a serious issue for geothermal power plants since it remarkably decreases the harvesting of energy. The reduction of pH by organic acids whose structure is close to CO2 for instance formic acid has been an effective solution for the minimization of scaling. Herein, the effect of CO2 injection on the formation of scaling particularly metal-silicates was investigated for the model case of Tuzla Geothermal Field (TGF) located in the northwest of Turkey. CO2 has an acidic character in aqueous systems because it leads to the formation of carbonic acid. The injection of 20.6 m3/s CO2 (approximately 88 ppm) to hypersaline brine of TGF is a promising green approach for both mitigation of scaling by reducing pH from 7.2 to 6.2 at the well-head and the minimization of potential corrosion compared to the use of formic acid (55 ppm).Article Citation - WoS: 14Citation - Scopus: 2Climate Change Mitigation With Renewable Energy: Geothermal(Springer Verlag, 2011) Baba, AlperOn a global scale, there is increasing evidence that climate is changing and of a discernible human influence. Many of scientists are confident that if current emissions of greenhouse gases continue, the world will be warmer, sea levels will rise and regional climate patterns will change. According to some scientist, global temperatures are expected to rise faster over the next century than over any time during the last 10,000 years. From this token, geothermal energy is now considered to be one of the most important alternative energy sources to minimize climate change. Geothermal technologies for power generation or direct use operate with little or no greenhouse gas emissions. Geothermal energy is generally accepted as being an environmentally-friendly energy source, particularly when compared to fossil fuel energy sources. Geothermal resources have long been used for direct heat extraction for district urban heating, industrial processing, domestic water and space heating, leisure and balneotherapy applications. Geothermal energy is used in more than 80 countries for direct heat application and 24 countries for power generation. Re-injection of fluids maintains a constant pressure in the reservoir, thus increasing the field's life and reducing concerns about environmental impacts. Geothermal energy has several significant characteristics that make it suitable for climate change mitigation.Article Citation - WoS: 25Citation - Scopus: 32District Heating System Design for a University Campus(Elsevier Ltd., 2006) Yıldırım, Nurdan; Toksoy, Macit; Gökçen Akkurt, Güldenİzmir Institute of Technology campus is in use since 2000 and still under development. At present, heating is provided by individual fuel boilers. On the other hand, the campus has a geothermal resource in its borders with a temperature of 33 °C. Because of this low geothermal fluid temperature; heat pump district heating system is considered for the campus. As an alternative, fuel boiler district heating system is studied. Each heating system is simulated using hourly outdoor temperature data. For the simulations, a control system with constant flow rate and variable return water temperature is used and the main control parameter is the indoor temperature. Various heating regime alternatives have been studied for heat pump district heating system for the various condenser outlet temperature and geothermal fluid flow rate, and two of these alternatives are given in this study. Furthermore, economic analysis has also been done for each heating system alternative based on investment and operational costs. Results indicate that heat pump district heating system has the highest investment but lowest operational cost. The alternatives are evaluated according to internal rate of return method, which shows the profit of the investment and resulted that, the heat pump district heating system has minimum 3.02% profit comparing with the fuel boiler district heating system at the end of the 20-year period.Article Citation - WoS: 30Citation - Scopus: 36Overview of Kizildere Geothermal Power Plant in Turkey(Elsevier Ltd., 2004) Gökçen Akkurt, Gülden; Öztürk, Harun Kemal; Hepbaşlı, ArifAchieving sustainable development is a target that is now widely seen as important in worldwide public opinion. In this context, the utilization of renewable energy resources such as solar, geothermal and wind energy appears to be one of the most efficient and effective ways of achieving this target. Recently, power generation from geothermal energy has become of big importance in Turkey, which is located on the Mediterranean sector of the Alpine-Himalayan Tectonic Belt and is among the first seven countries in abundance of geothermal resources around the world. The main objective in doing the present study is twofold, namely: (a) to investigate Turkey's geothermal energy potential for power generation and (b) to overview the Denizli-Kizildere geothermal power plant (DKGPP) with an installed capacity of 20.4 MWe, which is at present the only operating geothermal power plant of Turkey. Based on the drilling data, which have been gathered to date, Turkey's geothermal energy potential for power generation is determined to be 764.81 MWe. Electricity generation projections of Turkey are also 500 MWe from Germencik, Kizildere, Tuzla and several of the other fields by the year 2010 and 1000 MWe by 2020. The Denizli-Kizildere geothermal field has an estimated capacity of 200 MWe. The DKGPP was put into operation in 1984 and has been operated since then. It produced an electrical energy of 89,597 MWh in 2001, representing an electric power of 10.6 MWe in the same year. Present applications have shown that in Turkey, geothermal energy is a promising alternative and can make a significant contribution towards reducing the emission of greenhouse gases. As the public recognizes the projects, the progress will continue.