Contents lists available at ScienceDirect Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser Geothermal exploration using airborne gravity and magnetic data at Siwa Oasis, Western Desert, Egypt Mohamed Abdel Zaher a , Hakim Saibi b,c, ⁎ , Khamis Mansour a , Ahmed Khalil a , Mamdouh Soliman a a National Research Institute of Astronomy and Geophysics (NRIAG), 11421 Helwan, Cairo, Egypt b Department of Geology, College of Science, United Arab Emirates University, Al-Ain 15551, United Arab Emirates c Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan ARTICLE INFO Keywords: Aerogravity Aeromagnetic Curie Point Depth Geothermal resources Temperature gradients Heat flow ABSTRACT Siwa Oasis is a part of the greatest northern depression in the Egyptian Western Desert, located just 50 km east of the Libyan border. It represents one of the most interesting potential candidates for the development of the Northern Western Desert of Egypt. Temperature data from deep wells in the Western Desert of Egypt indicate low geothermal resources. Here, we present the contribution of airborne gravity and magnetic geophysical data for the preliminary exploration of geothermal potential in Siwa Oasis. To achieve this objective, a 3D inversion of aerogravity data was used to delineate the depths to basement rocks, while spectral analysis of the aero- magnetic data was used to estimate the Curie Point Depth (CPD) and provide geothermal gradient and heat flow maps for the Siwa Oasis. The depth to the Precambrian basement rock is commonly greater than 2 km, ranging from 2 km to 5 km, whereas the CPDs range from 21 km to 28 km. Our results imply an inverse relationship between these two depths, in which the deeper basement regions are associated with shallow Curie depths. The derived geothermal gradients range from 21 to 27 °C/km and the heat-flow values range from 49 to 64 mW/m 2 for the study area. 1. Introduction In a national appeal, the Egyptian Supreme Energy Council reported the state's arrangement, which plans to get the commitment of new and renewable energy at around 20% in power production of the aggregate demand. Among the promising renewable energies are the geothermal sources. Geothermal resources supplies crucial information on the re- newable vitality source tapped from the Earth's interior heat. They can be used as energy sources in several ways, from extensive and complex power stations, to small and relatively simple pumping systems. Similar to other renewable energy, the use of geothermal resources can reduce emissions of CO 2 and local air pollutants and can provide a magnificent fence against energy price shocks and contribute to energy security. The Western Desert of Egypt is comprised of various extensive de- pressions, which form inhabited oases. The Siwa Oasis is located in the far west of Egypt, approximately 50 km east of the Libyan border, sit- ting approximately 18 m below sea level [1] and stretching for more than 50 km from the East to the West (Fig. 1). Several studies provide insight into the structure geology and hydrogeology of the Western Desert of Egypt; however, few attempts have been made to compre- hensively analyze and describe its geothermal potentiality [2]. used gravity and borehole data to determine the thickness of the main sandstone water-bearing formation in the southern part of Western Desert of Egypt by developing an Artificial Neural Network (ANN) model [3]. Carried out proposing and testing chain water management scenarios in Siwa Oasis to ensure its sustainable development [4]. De- veloped multilayer groundwater model for water resource management in Siwa Oasis to characterize the ideal pumping scenarios able to moderate environmental issues In the present study, we briefly reviewed the geothermal resources potentiality of Egypt with a particular focus on the Western desert and Siwa Oasis. Additionally, airborne geophysical data in forms of aero- gravity was used to delineate the subsurface basement configuration and its correlation with the obtained thermal characteristics from available aeromagnetic data analyses using power spectrum method. This correlation will ultimately help to estimate the geothermal po- tential in the Siwa Oasis. 3D unconstrained inversion was applied to the aerogravity data to estimate a 3D density model, whose gravity re- sponse fits the measured gravity anomaly. While, spectral analysis of the aeromagnetic data was conducted to estimate the Curie Point Depth (CPD) and provide geothermal gradient and heat flow maps for the Siwa Oasis. The results will be helpful for future geothermal http://dx.doi.org/10.1016/j.rser.2017.10.088 Received 23 August 2016; Received in revised form 4 June 2017; Accepted 28 October 2017 ⁎ Corresponding author at: Department of Geology, College of Science, United Arab Emirates University, Al-Ain 15551, United Arab Emirates. E-mail address: hakim.saibi@uaeu.ac.ae (H. Saibi). Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx 1364-0321/ © 2017 Elsevier Ltd. All rights reserved. Please cite this article as: Abdel Zaher, M., Renewable and Sustainable Energy Reviews (2017), http://dx.doi.org/10.1016/j.rser.2017.10.088