Peter Meisen, Past President, Global Energy Network Institute, asked in 1997, "What if there was an existing, viable technology, that when developed to its highest potential could increase everyone's standard of living, cut fossil fuel demand and the resultant pollution?" After 23 years of sustained effort by the global scientific community, this is becoming a reality.

The technology to extract heat from granite has been revolutionized in the last few years. The classical method of creating fracture networks by hydrofracturing is being replaced by a closed-loop method where fluids are not in contact with the hot granite. Supercritical CO2 is replacing water as a circulating fluid. Certainly, the future energy road is going to be led by highly radiogenic granites. While hydrothermal sources are site-specific and have their limitations, EGS can be initiated anywhere on earth. EGS is removing all such obstacles and, in the future, will provide uninterrupted electricity for all. Energy-deficient countries can have surplus electricity; water-stressed countries can have a perennial freshwater supply; and countries can become food-secure and rise above poverty levels. Countries need not depend on energy imports and can independently evolve into carbon neutral or low carbon societies.

The contributions made by experts will help researchers and investors to close the energy demand and supply gap in the very near future by tapping the unlimited energy of the Earth.

Opportunities available for investors in Turkey are well documented with field, geophysical, and geochemical data and information on the energy generating capacity of the granite intrusive spread over a cumulative area of 6,910 km2 in western Anatolia.

With the signing of the Global Geothermal Alliance (GGA) by several countries during the December 2015 CoP 21 (Conference of Parties) summit in Paris, countries are obliged to reduce CO2 emissions by increasing the footprint of renewable energy in the primary source mix. Information provided in this book will lead the way to establishing a clean energy future for millions of people for sustainable development and help to mitigate crises arising due to food, water, and energy shortage issues. Academic and research institutes will benefit to a large extent from the expertise of the top contributors in this book. This information provided in this book will help to lay the foundation for super-hot EGS research in future.

Dornadula Chandrasekharam (Chandra: b1948, India), TUBITAK Fellow, Izmir Institute of Technology (IYTE), Turkey, obtained his MSc in Applied Geology (1972) and PhD (1980) from IITB. He has been working in the fields of geothermal energy resources, volcanology and groundwater pollution for the past 45 years. Before joining IITB, he worked as a Senior Scientist at the Centre for Water Resources Development and Management and the Centre for Earth Science Studies in Kerala, India, for 7 years. he held several important positions during his academic and research career. Before joining IYTE, He served as a Chair Professor, Indian Institute of Technology Bombay (1987-2015) and Visiting Professor, Indian Institute of Technology Hyderabad (2016-2021). He was a TWAS Visiting Professor to Sanaa University, Yemen Republic (1996-2001); Senior Associate of Abdus Salam International Centre for Theoretical Physics, Trieste, Italy (2002-2007); Adjunct Professor, China University of Geosciences, Wuhan (2011-2012), Visiting Professor to King Saud University of Saudi Arabia (2011-2017) and Adjunct Professor, University of Southern Queensland, Australia (2016-2019). He received the International Centre for Theoretical Physics (ICTP, Trieste, Italy) Fellowship to conduct research at the Italian National Science Academy (CNR) in 1997. Prof. Chandra extensively conducted research in low-enthalpy geothermal systems in India and is currently the Founder Chairman of M/s GeoSyndicate Power Private Ltd., the only geothermal company in India. He was an elected board member of the International Geothermal Association (2010-2016) and has widely represented his country at several international geothermal conferences. He conducted short courses on low-enthalpy geothermal resources in Argentina, Costa Rica, Poland, China and Turkey. He has supervised 25 PhD students, published 210 papers in peer-reviewed journals of international repute and published 7 books in the fields of groundwater pollution and geothermal energy resources. His books on geothermal energy resources (i) Geothermal Energy Resources for Developing Countries (Balkema Pub., 2002), (ii) Low Enthalpy Geothermal Resources for Power Generation (Taylor and Francis, 2008), (iii) Geothermal Systems and Energy: Turkey and Greece (CRC Press, 2014) and (iv) Red Sea Geothermal Provinces (CRC Press, 2018) are widely read. Prof Chandra served on the Board of Director of (i) Oil and Natural Gas Corporation, (ii) Western Coal Fields Ltd., (iii) Indian Rare Earths Ltd. and (iv) Mangalore Refineries and Petrochemicals. He has been appointed as the Chairperson of the Geothermal Energy Resources and Management committee constituted by the Department of Sciences and Technology, Government of India. Currently, he is with the International Water Resources Department, IYTE, Turkey.

Alper Baba (Turkey, 1970) holds a degree in geology and a doctorate in the field of hydrogeology from Dokuz Eylul University, Izmir. He has 25 years' experience in hydrogeological and environmental geology problems in different parts of the world. Since 2010, he has been a professor at the Izmir Institute of Technology as the director of the International Water Resources Department. He is teaching and conducting research in the fields of environmental geology, groundwater contamination, geothermal energy and hydrogeology. He has coordinated a variety of national and international R&D projects in cooperation with research institutes and companies, among them NATO, World Bank and EBRDfunded projects. Dr. Baba was awarded the "Successful Young Scientists Award" of the Turkish Academy of Science and the "Gold Medal Award" of the Turkish Geological Engineering Association Dr. Baba is the author of several peer-reviewed scientific publications and contributions to international conferences and is the editor of the books "Groundwater and Ecosystems," "Climate Change and its Effects on Water Resources, Issues of National and Global Security" (NATO Science Series, Springer) and "Geothermal Systems and Energy: Turkey and Greece" (CRC Press). Currently, he is the Vice Rector of the Izmir Institute of Technology, Izmir.