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In this paper we present results of a global resource assessment for geothermal energy within deep aquifers for direct heat utilization. Greenhouse heating, spatial heating, and spatial cooling are considered in this assessment. We derive subsurface temperatures from geophysical data and apply a volumetric heat-in-place method to improve current global geothermal resource base estimates for direct heat applications. The amount of thermal energy stored within aquifers depends on the Earth's heat flow, aquifer volume, and thermal properties. We assess the thermal energy available by estimating subsurface temperatures up to a depth of three kilometer depending on aquifer thickness. The distribution of geothermal resources is displayed in a series of maps and the depth of the minimum production temperature is used as an indicator of performance and technical feasibility. Suitable aquifers underlay 16% of the Earth's land surface and store an estimated 4·105 to 5·106 EJ that could theoretically be used for direct heat applications. Even with a conservative recovery factor of 1% and an assumed lifetime of 30 years, the annual recoverable geothermal energy is in the same order as the world final energy consumption of 363.5 EJ yr−1. Although the amount of geothermal energy stored in aquifers is vast, geothermal direct heat applications are currently underdeveloped with less than one thousandth of their technical potential used. © 2017 The Author(s)

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Avrasya Yer Bilimleri Enstitüsü, Thesis (M.Sc.) -- İstanbul Technical University, Eurasia Institute of Earth Sciences, Bu araştırma, İ.T.Ü Avrasya Yer Bilimleri Enstitüsü Jeodinamik Anabilim Dalı'nda yüksek lisans tez çalışması kapsamında yapılmıştır. Çalışma alanı için İstanbul Boğazı'nın doğu yakasında, batıda Akbaba Köyü , doğuda Paşamandıra, kuzeyde Kaynarca bölgesi güneyde Gümüşsuyu mahallesi arasındaki bölge seçildi. Bu bölgenin seçilmesinin nedeni hızla gelişen yerleşime bağlı olarak açılan yol ve yarmalar, inceleme alanını, İstanbul-Kocaeli Paleozoik yaşlı istifin deformasyon özelliklerini aydınlatmak için oldukça elverişli duruma getirmesidir. Ayrıca görece yeni açılmış mostralar, özellikle deforme olmuş bölgelerdeki küçük ölçekli mostraların gerek atmosferik koşullara gerekse hızla tahrip olmasına neden olmaktadır. Bu nedenle, bölgedeki yapısal evrime ışık tutacak mostralardaki değerli mikro-yapısal verilerin hızlıca belgelenmesi büyük önem taşımaktadır. İnceleme alanında, ayrıca İstanbul-Kocaeli Paleozoik istifinde tanımlanan neredeyse tüm farklı formasyonların mostra vermiş olması ve bu formasyonlar için tanımlayıcı ayrıntılı ölçülü yapısal kesitler almaya elverişli mostralar bulunmaktadır., Yüksek Lisans, M.Sc.

We present a new model of P-velocity anomalies in the upper mantle beneath the Arabian Peninsula, Red Sea, and surrounding regions. This model was computed with the use of travel time data from the global catalogue of the International Seismological Center (ISC) for the years of 1980–2011. The reliability of the model was tested with several synthetic tests. In the resulting seismic model, the Red Sea is clearly associated with a higher P-velocity anomaly in the upper mantle at least down to 300 km depth. This anomaly might be caused by upward deviation of the main mantle interfaces caused by extension and thinning of the lithosphere due to passive rifting. Thick lithosphere of the Arabian Platform is imaged as a high-velocity anomaly down to 200–250 km depth. Below this plate, we observe a low-velocity structure that is interpreted as a hot mantle upwelling. Based on the tomography results, we propose that this upper mantle anomaly may represent hot material that migrates westward and play a major role in the formation of Cenozoic basaltic lava fields in western Arabia. On the northeastern side of the Arabian Plate, we clearly observe a dipping high-velocity zone beneath Zagros and Makran, which is interpreted as a trace of subduction or delamination of the Arabian Plate lithosphere.