Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Sustainable Recovery of Critical Raw Materials From Geothermal Igneous Systems: Geochemical, Mineralogical, and Techno-Economic Insights from the Dikili-Bergama Field (Western Anatolia, Turkiye)(Elsevier, 2026) Ayzit, Tolga; Baba, AlperThe sustainable co-extraction of critical raw materials (CRMs) with renewable geothermal energy offers a dual pathway to support the circular economy and low-carbon transition. In this study, an integrated geochemical and mineralogical approach is used to comprehensively assess the recoverable lithium (Li) boron (B), strontium (Sr) and other critical raw materials in the geothermal reservoirs of the Dikili-Bergama region Turkiye. A geochemical analysis was carried out by systematic sampling and multi-element testing of geothermal water and reservoir rock. Hydrogeochemical studies of the geothermal fluids indicated the presence of remarkable concentrations of B (4.6 ppm), Sr (2.8 ppm) and Li (1.2 ppm), suggesting the possibility of active leaching processes in the deposit. Mineralogical studies using X-ray diffraction (XRD) have revealed a number of secondary mineral phases, such as quartz and labradorite, indicating the interaction between water and rock. These interactions affect not only the permeability and porosity of the deposit, but also the mobilization and precipitation of CRMs. A techno-economic analysis will be used to identify potential synergies that could improve the economic feasibility of geothermal projects in the region. The Monte Carlo simulation has shown that the Dikili-Bergama geothermal reservoirs have a potential of similar to 712 tons of Li. In this study, the CRM potential that emerged during the geothermal energy exploitation process in the region was calculated. The temporality and the process of obtaining are completely related to the extraction technology. This offers the dual benefit of renewable energy and strategic mineral extraction, contributing to sustainable resource management in volcanic environments.Article Development and Validation of Regression Model via Machine Learning to Estimate Thermal Conductivity and Heat Flow Using Igneous Rocks from the Dikili-Bergama Geothermal Region, Western Anatolia(Pergamon-Elsevier Science Ltd, 2026) Ayzit, Tolga; Sahin, Onur Gungor; Erol, Selcuk; Baba, AlperThermal conductivity is a fundamental parameter that significantly influences the thermal regime of the lithosphere. It plays a crucial role in a variety of geological applications, including geothermal energy exploration, igneous system assessment, and tectonic modeling. In this study, a machine learning approach is used to predict the thermal conductivity of igneous rocks based on the composition of major oxides. A total of 488 samples from different regions of the world were analyzed. The thermal conductivity values ranged from 1.20 to 3.74 Wm(-1) K-1 and the mean value was 2.61 Wm(-1) K-1. The Random Forest (RF) algorithm was used, resulting in a high coefficient of determination (R-2 = 0.913 for training and R-2 = 0.794 for testing) and a root mean square error (RMSE) of 0.112 and 0.179, respectively. Significance analysis of the traits identified SiO2 (>40 %), Na2O (>15 %) and Al2O3 (>10 %) as the most influential predictors. The study presented results from the Western Anatolia region, where felsic rocks had the highest thermal conductivity (mean = 2.69 Wm(-)(1)K(-)(1)) compared to mafic (mean = 2.34 Wm(-)(1)K(-)(1)) and ultramafic rocks (mean = 2.39 Wm(-)(1)K(-)(1)). In addition, the study evaluated the predictive capabilities of machine learning models for the igneous rocks of the Dikili-Bergama region and compared the results with those of saturated models. Using these data, we calculated heat flow values of up to 400 mWm(-2) under saturated conditions in western Anatolia. These results highlight the value of integrating geochemical data with machine learning to improve geothermal resource exploration and lithospheric modeling.Article Citation - WoS: 1Citation - Scopus: 1Petrogenesis and Comprehensive Thermal Assessment of the Dikili-Bergama Region, Western Anatolia(Pergamon-elsevier Science Ltd, 2025) Ayzit, Tolga; Erol, Selcuk; Baba, AlperVarious methods are available to evaluate the thermal properties and energy potential of geothermal fields. The heat flow method is crucial for thermal modeling and understanding geological evolution. It helps to assess the impact of geological formations on various processes, including hydrocarbon generation and structural modeling. This study focuses on the Dikili-Bergama geothermal region and presents heat flow trends based on thermal modeling. The analysis of volcanic rock petrogenesis data and a thermal model are presented based on data from deep and shallow boreholes. The geothermal gradient is found to vary between 66.28 degrees C km-1 and 121.68 degrees C km-1, according to the interpolated data. Additionally, the study investigates the geochemical and lithological properties of magmatic rocks in the Dikili-Bergama region. The Kozak pluton group's has been measured to have radioactive heat production of up to 7.4 mu Wm-3. Thermal conductivity properties and correlations, along with heat flow assessment, contribute to the understanding of geothermal potential. The mean dry thermal conductivity of the rocks in the study area is 2.33 Wm-1K-1. The data for the terrestrial heat flow and the radioactive heat flow values are up to 200 mWm-2. The integration of 3D geological models and thermal models has highlighted the south western area of the study as a promising location for unconventional geothermal operations.Article Citation - WoS: 4Citation - Scopus: 6A Sustainable Clean Energy Source for Mitigating Co<sub>2</Sub> Emissions: Numerical Simulation of Hamit Granitoid, Central Anatolian Massif(Springer Heidelberg, 2024) Ayzit, Tolga; Singh, Mrityunjay; Chandrasekharam, Dornadula; Baba, AlperT & uuml;rkiye relies on coal-fired power plants for approximately 18 GW of annual electricity generation, with significantly higher CO2 emissions compared to geothermal power plants. On the other hand, geothermal energy resources, such as Enhanced Geothermal Systems (EGS) and hydrothermal systems, offer low CO2 emissions and baseload power, making them attractive clean energy sources. Radiogenic granitoid, with high heat generation capacity, is a potential and cleaner energy source using EGS. The Anatolian plateau hosts numerous tectonic zones with plutonic rocks containing high concentrations of radioactive elements, such as the Central Anatolian Massif. This study evaluates the power generation capacity of the Hamit granitoid (HG) and presents a thermo-hydraulic-mechanical (THM) model for a closed-loop geothermal well for harnessing heat from this granitoid. A sensitivity analysis based on fluid injection rates and wellbore length emphasizes the importance of fluid resident time for effective heat extraction. Closed-loop systems pose fewer geomechanical risks than fractured systems and can be developed through site selection, system design, and monitoring. Geothermal wellbore casing material must withstand high temperatures, corrosive environments, and should have low thermal conductivity. The HG exhibits the highest heat generation capacity among Anatolian granitoid intrusions and offers potential for sustainable energy development through EGS, thereby reducing CO2 emissions.Book Part Citation - Scopus: 3High Radiogenic Granites of Western Anatolia for Egs: a Review(CRC Press, 2023) Chandrasekharam, Dornadula; Baba, Alper; Ayzit, TolgaTurkey has made remarkable progress in the hydrothermal sector by promoting both electricity generation and direct application. In terms of power generation, this country is the fourth top country in the world. Nearly 1 billion kWh of energy is being utilized to keep 150,000 homes warm in the winter. In addition, Turkey has huge amounts of uptapped energy in its high radiogenic granites in western Anatolia, spread over a cumulative area of 6,910 km2. The radioactive heat generated by these granites varies from 5 to 13 µW/m3. These granite plutons are located over a region with high heat flow values (120 mW/m2) and the Curie temperature isotherm in this region is located at a depth varying from 6 to 12 km. The heat flow values here are 50% higher than the world average. This thermal regime concurs well with the wet granite melting curve at a heat flow of 85 mW/m2. The entire thermal regime indicates a visco-elastic lower crustal layer in this region. Thus, these granites provide excellent sites for initiating Enhanced Geothermal Systems projects in Turkey. Earlier EGS projects in France and Australia gave power estimates of 79×106 kWh of electricity from 1km3 of such granite. With ongoing development in drilling technology, the classical concept of creating a fracture network is being replaced with loop technology that reduces minor seismic risks and also the cost of power. The most important additional advantage Turkey has is the high-temperature regime at shallow depth, unlike other countries where the granites are located at depths >5km. These factors cause the cost of power to fall below 6 euro cents per kWh. Besides the power and heat, the greatest advantage is the reduction in emissions and achieving UN sustainable development goals. A conservative estimate shows that these radiogenic granites of western Anatolia are capable of generating a minimum of 546×109 kWh of power. Energy from these granites can be utilized to generate freshwater using the desalination method. Earlier studies indicate that to produce 1 m3 of desalinated water, ~16 kWh of electrical energy are needed. The cost of fresh water generated using geothermal energy sources will be <1.5 euros per 1m3. Turkey can utilize the energy from granite for water and food security in the future. © 2024 selection and editorial matter, Dornadula Chandrasekharam and Alper Baba.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.