Civil Engineering / İnşaat Mühendisliği
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Article Citation - WoS: 40Citation - Scopus: 44Geological and Hydrogeochemical Properties of Geothermal Systems in the Southeastern Region of Turkey(Elsevier Ltd., 2019) Baba, Alper; Şaroğlu, Fuat; Akkuş, I.; Özel, Nedret; Yeşilnacar, Mehmet İrfan; Nalbantçılar, Mahmut Tahir; Demir, Mustafa Muammer; Gökçen, Gülden; Arslan, Ş.; Dursun, N.; Uzelli, Taygun; Yazdani, HamidrezaThe Anatolia region is one of the most seismically active regions in the world. It has a considerably high level of geothermal energy potential thanks to its geological and tectonic settings. The Southeastern Anatolia Region (GAP) is located in the south of Bitlis-Zagros Suture Zone (BZSZ) which is in the Arabian foreland. During the neotectonic period, the folded structures have been developed under the influence of tectonic compression from the Upper Miocene in the GAP Region where it is closely related to active tectonics. These tectonic activities produce more geothermal resources. Few studies have been carried out in this region for geothermal energy. Limited portions of the geothermal resources have been used both for thermal tourism and greenhouses in the GAP region. The aim of this study is to determine geological, tectonic and hydrogeochemical properties of a geothermal system in the GAP Region. The result indicates that the surface temperatures of geothermal fluids are from 20 to 84.5 °C A large number of abandoned oil wells, whose temperature reaches 140 °C, are found in the region. Also, hydrogeochemical results show that deep circulated geothermal fluids are enriched with Na-Cl and shallow geothermal system fluids have Na−HCO 3 and Ca-SO 4 characters because of cold water mixing and water-rock interaction. Cold waters are generally of Ca-Mg−HCO 3 and Ca−HCO 3 type. Cation geothermometers were used for determining reservoir temperature of the geothermal resources in the region. The results show that the reservoir temperature of these geothermal resources ranges from 50 °C to 200 °C. The isotope data (oxygen-18, deuterium and tritium) suggests that geothermal fluid is formed by local recharge and deep circulation.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: 21Citation - Scopus: 27Increasing Solubility of Metal Silicates by Mixed Polymeric Antiscalants(Elsevier Ltd., 2019) Topçu, Gökhan; Çelik, Aslı; Kandemir, Ali; Baba, Alper; Şahin, Hasan; Demir, Mustafa MuammerThe increase of silicate solubility is a big challenge for both hot and cold water because it reduces the deposition of metal silicates frequently observed in such systems and causes operational obstacles. The deposition of silicate coats the inner surface of the pipelines in an uncontrolled manner and reduces the harvesting of energy from brines. In this work, the solubility performance of two commercial water-soluble polymeric agents (poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA)) of various molecular weights employing dosage from 25 to 100 mg/L was examined. Along with dispersant-type antiscalant, poly(acrylamide) (PAM), poly(vinylsulfonic acid, sodium salt) (PVSA), and poly(vinylphosphonic acid) (PVPA) having chelating acidic groups were employed. Metal silicate deposits were obtained artificially in the lab-scale pressurized reactor. The experimental conditions employed were quite similar to a model power plant located in Çanakkale, Turkey. The concentration of dissolved silica was increased from 130 to 420 mg/L when 100 mg/L PEG 1500 and 25 mg/L PVSA were employed as a mixture. For the atomic-level understanding of the interaction of chelating groups with metal cations, DFT calculations were performed too.Article Citation - WoS: 18Citation - Scopus: 15Thermal Fluid Circulation Around the Karliova Triple Junction: Geochemical Features and Volcano-Tectonic Implications (eastern Turkey)(Elsevier Ltd., 2019) Baba, AlperThe Karlıova triple junction (KTJ) in eastern Turkey has been subjected to incremental deformation resulting in complex kinematic and mechanical interactions throughout the upper crust. These interactions have generated tectonic inversions and uplift, extensive seismicity and volcanism. The regional tectonics generate local stresses, some of which are favorable to magma transport and thermal water circulation throughout the lithosphere. Here we evalauate hydrogeochemical, geological and numerical results relating to the mechanism of thermal fluid circulation around the KTJ. Hydrogeochemistry of the samples indicates that the thermal water springs are probably heated by steam. Volcanic rocks at the site appear to be the host rock owing to the enrichment of Na+ and Cl− ions in water and the abundance of these elements in minerals of the volcanic rocks. In addition, it is clear that the thermal fluids are sourced from depth and migrate through permeable networks of faults. The effects of crustal heterogeneities, in particular the geometry and mechanical properties of many faults and layers, on thermal fluid circulation in relation to active magma chambers were investigated under a variety of different mechanical conditions. The numerical results indicate very close relationships between the stress field causing faulting and thermal fluid movement in the KTJ. The effect of thermal transfer was modeled with depth throughout the crust and along the the crustal surface. The models show that some faults encourage thermal fluid circulation below the Varto and Özenç volcanoes. Hydrogeochemical, geological and numerical results suggest that magmas residing beneath both the Varto caldera and the Özenç volcano are the main heat source for thermal fluid in the Varto region. Fluid-solid interactions and fluid circulation models show that the permeable faults are important factors affecting heat transport and fluid circulation. In a series of thermal fluid flow models we probe the mechanism for fluid and gas transport from the 900 °C ‘hot’ zone around the deep magma chambers and investigate how heat is lost throughout the crust on the way to the surface and so eventually creates water channels of temperatures between 50 to 60 °C.Article Citation - WoS: 13Citation - Scopus: 16Experimental Modeling of Silicate-Based Geothermal Deposits(Elsevier Ltd., 2017) Çelik, Aslı; Topçu, Gökhan; Baba, Alper; Akdoğan, Yaşar; Şentürk, Ufuk; Demir, Mustafa MuammerScaling by metal silicates represents a major obstacle for geothermal systems. A composition that enables the fabrication of artificial deposits is necessary for the rapid testing of potential inhibitors. In this work, artificial deposits were synthesized by employing experimental conditions similar to those in the Tuzla Geothermal Field in Turkey. Although refluxing enabled the formation of a precipitate that was similar to naturally formed deposits in color and texture, their elemental composition and morphology showed a mismatch. An autoclave enabled the production of a precipitate that more closely resembled naturally formed deposits in color, texture, elemental composition, and structure.Article Citation - WoS: 26Citation - Scopus: 25Conceptual Model of the Gülbahçe Geothermal System, Western Anatolia, Turkey: Based on Structural and Hydrogeochemical Data(Elsevier Ltd., 2017) Uzelli, Taygun; Baba, Alper; Mungan, Gamze Gül; Dirik, Ramazan Kadir; Sözbilir, HasanThe Gülbahçe Geothermal Field is located on the eastern margin of the Karaburun Peninsula, about 45 km from the city of İzmir, western Anatolia, Turkey. The stratigraphy of the study area is represented by a Miocene volcano-sedimentary succession, including several sedimentary and volcanic units. These units overlie the basement rocks of the Karaburun Platform and Bornova Flysch Zone which consist of sandstones, shales and carbonate blocks. These rock units are cut and deformed by a series of NW-SE- to NE-SW-trending faults, extending from Sığacık Bay to Gülbahçe Bay. Structural studies suggest that while most of the geothermal systems in western Anatolia are controlled by normal faults, the geothermal system at Gülbahçe is controlled by a strike-slip dominated shear zone, previously named the İzmir-Balıkesir Transfer Zone. Along the fault zone, associations of active fault segments accommodate deep circulation of hydrothermally modified sea water, and thus the resulting negative flower structure is the primary control mechanism for the geothermal system. Hydrogeochemical properties of the field show that surface temperature of fluid ranges from 30 to 34 °C. Geothermal fluids in Gülbahçe have high salinity (EC > 34 mS/cm) and low enthalpy. Piper and Schoeller diagrams indicate that geothermal fluid is in the NaCl facies. Chemical geothermometers suggest that the reservoir temperature is around 53–136 °C. The isotopic data (oxygen-18, deuterium and tritium) suggest that geothermal fluids are formed by local recharge and deep circulation of sea water.Article Citation - WoS: 72Citation - Scopus: 90Naturally Occurring Arsenic in Terrestrial Geothermal Systems of Western Anatolia, Turkey: Potential Role in Contamination of Freshwater Resources(Elsevier Ltd., 2013) Bundschuh, Jochen; Maity, Jyoti Prakash; Nath, B.; Baba, Alper; Gündüz, Orhan; Kulp, Thomas R.; Jean, Jiin-Shuh; Kar, Sandeep; Yang, Huai-Jen; Tseng, Yujung; Bhattacharya, Prosun; Chen, ChienyenArsenic (As) contamination in terrestrial geothermal systems has been identified in many countries worldwide. Concentrations higher than 0.01mg/L are detrimental to human health. We examined potential consequences for As contamination of freshwater resources based on hydrogeochemical investigations of geothermal waters in deep wells and hot springs collected from western Anatolia, Turkey. We analyzed samples for major ions and trace element concentrations. Temperature of geothermal waters in deep wells showed extreme ranges (40 and 230°C), while, temperature of hot spring fluids was up to 90°C. The Piper plot illustrated two dominant water types: Na-HCO3 - type for geothermal waters in deep wells and Ca-HCO3 - type for hot spring fluids. Arsenic concentration ranged from 0.03 to 1.5mg/L. Dominance of reduced As species, i.e., As(III), was observed in our samples. The Eh value ranged between -250 and 119mV, which suggests diverse geochemical conditions. Some of the measured trace elements were found above the World Health Organization guidelines and Turkish national safe drinking water limits. The variation in pH (range: 6.4-9.3) and As in geothermal waters suggest mixing with groundwater. Mixing of geothermal waters is primarily responsible for contamination of freshwater resources and making them unsuitable for drinking or irrigation.Article Citation - WoS: 61Citation - Scopus: 69Leaching Characteristics of Fly Ash From Fluidized Bed Combustion Thermal Power Plant: Case Study: Çan (çanakkale-Turkey)(Elsevier Ltd., 2010) Baba, Alper; Gürdal, Gülbin; Şengünalp, FatmaIt is known that the concentration of elements of fly ash varies due to the used-coal and the used-lime qualities varying in different periods. In the Çan Thermal Power Plant (CTPP) located at northwestern Turkey, Çan (Çanakkale) basin coals, which are classified as lignite to sub-bituminous C coal with high total sulphur (0.4-12.22%) and a broad range of ash contents (3.2-44.6%) are mainly used. Performed studies reveal that some toxic elements exit in the coal, including As, U and V. Also, while the As, Cu, Co and Hg contents in coal increases, the sulphur contents in coal also increase. Additionally, trace elements that have inorganic compounds in coal are mobilized into air during the combustion process. This poses a big risk for human health and keeping the environment when Çan Basins low quality lignite is burned, it's the fly ash that contains several toxic elements which can leach out and contaminate the water resources. In this study, toxicity tests were conducted on the fly ash samples that were obtained from the fluidized bed combustion of Çan Thermal Power Plant. The results showed that water temperature, pH and the quality of the limestone used were the most important factors affecting the leaching properties. Concentration of some toxic elements found in the fly ash, such as; As, Cd, Cr, Pb, Se and Zn were analyzed. Concentration richness of some heavy metals were attributed to the increase of water temperature, especially when pH is lower than 5. At pH=5 value, there is no clear explanation of each heavy metal presence in the fly ash from fluidized bed combustion thermal power plant. © 2010 Elsevier B.V. All rights reserved.Article Citation - WoS: 35Citation - Scopus: 45Types of the Scaling in Hyper Saline Geothermal System in Northwest Turkey(Elsevier Ltd., 2014) Demir, Mustafa Muammer; Baba, Alper; Atilla, Vedat; İnanlı, MustafaTuzla is an active geothermal area located in northwestern Turkey, 80km south of the city of Canakkale and 5km from the Aegean Coast. The geothermal brine from this area, which is dominated by NaCl, has a typical temperature of 173°C. Rapid withdrawal of fluid to ambient surface conditions during sampling causes precipitation of various compounds known as scaling. Scaling is one of the important problems in Tuzla geothermal system that reduces the efficiency of the geothermal power plant and causes economical loss. The aim of this study was to determine the type of scaling as a first step towards preventing its formation. The scales formed in the geothermal system were divided into two groups according to location: the ones that formed in downhole and the ones that accumulated along the surface pipeline. Both scales were examined in terms of their elemental composition, structure and morphology using XRF, XRD, and SEM, respectively. The former was found to be mainly composed of PbS (Galena) and CaCO3 (aragonite or calcite). In contrast, the latter was heterogeneous in nature and consisted of mainly saponite like amorphous structure along with submicrometer-sized amorphous silica particles, layered double magnesium and iron hydroxide, and NaCl.