Special issue Title: Sustainable development and utilization of geothermal systems Geothermal energy is continuously renewed, clean energy which has a substantial net positive impact on the environment compared to the conventional energy resources. In recent years, great advances have been achieved in geothermal exploration, deep drilling, reservoir stimulation, reservoir modelling, geochemistry, and other areas of geosciences. These exercises have contributed to the primary understanding and the steady growth of the geothermal industry. Although the deep geothermal systems have huge resource potential, present commercial geothermal energy production has mostly been limited to geothermal areas with accessible heat sources where significant amounts of fluids are available. Utilization of the unconventional geothermal resources is currently a great challenge for the geothermal industry which require high-levels of innovation, research and development, and technological advances. This includes enhancing the permeability of the reservoir rock to enlarge the extent of productive geothermal fields (by means of hydraulic, thermal, and chemical stimulation technologies), improving drilling and reservoir assessment technology, improving the thermodynamic cycle, introducing supercritical/smart fracturing and circulation fluids and improving resource exploration and reservoir characterization techniques. Facing the dynamic and fast-growing progression of the industry, the goal of this special issue is to explore the recent contributions on science and technology to enhance the heat recovery from the geothermal systems. We will particularly welcome submissions on the following topics: • Conventional geothermal systems • Enhanced geothermal systems • Heat pumps and geothermal direct use applications • Geothermal resource exploration and assessment • Challenges in deep drilling in geothermal reservoir rocks • Geothermal reservoir stimulation techniques • Coupled thermo-hydro-chemical-mechanical processes in the geothermal reservoir • Analysis and modelling of hydraulic fracture initiation and propagation • Use of innovative fracturing and circulations fluids • Geochemical interactions in the geothermal reservoir • Theoretical and numerical modelling of coupled thermal-mechanical-fluid flow systems • Field and laboratory scale experimental studies on rocks at high temperature • Induced seismicity in geothermal reservoirs • Environmental, economic and social concerns of geothermal development • Case studies of international interest Deadline: 30th of July Guest Editors 1. Prof. Ranjith Pathegama Gamage Deep Earth Energy Laboratory, Civil Engineering Dept, Monash University, Australia email: [email protected] Research Interests Deep geothermal energy, Geological sequestration of carbon dioxide, Unconventional oil and gas (Shale gas, tight gas, coal seam gas), Petroleum geomechanics, In-situ leaching, Mining geomechanics, Rock mechanics, Enhanced oil recovery methodologies (EOR), Sand production from unconsolidated reservoirs, Wellbore stability, Well cement. 2. Prof. D. Chandrasekharam Department of Earth Sciences Indian Institute of Technology Hyderabad, India email: [email protected] Research Interests Groundwater resources assessment/ evaluation, Chemical evolution of geothermal springs, Geothermal energy resources evaluation, Deccan volcanics, Barren island and narcondum volcanos 3. Prof. Ilmutdin Abdulagatov Thermophysical Division at the Geothermal Research Institute of the Russian Academy of Sciences, Dagestan State University, Russia email: [email protected] Research Interests Renewable energy technologies, hydro-thermal treatment, Thermodynamic properties of ionic liquids, nano-fluids, Biofuel production, Geological sequestration of carbon dioxide, 4. Assistant Professor Bisheng Wu State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China email: [email protected] Research Interests Numerical modelling on hydraulic fracturing in unconventional gas/oil extraction, enhanced geothermal systems, Multiscale modelling on heat and mass transfer, carbon dioxide storage, sand production 5. Dr. Pabasara Wanniarachchige Deep Earth Energy Laboratory, Civil Engineering Dept, Monash University, VIC 3800, Australia email: [email protected] Research Interests Deep geothermal extraction, Hydraulic fracturing in unconventional geothermal systems, gas/oil extraction, Thermo-hydro-mechanical and chemical coupling http://www.springer.com/journal/40948.