Preface

The term "geothermal energy" refers to the Earth's natural heat energy. The continual heat energy flux coming from the Earth's core to the surface is the source of geothermal energy. The Earth's geothermal resources are huge; for example, the portion of geothermal energy stored at a depth of 3 km is estimated to be 1,194,444,444 TWh, which is substantially more than the total energy equivalent of all fossil fuel resources combined, which is estimated to be 1,010,361 TWh. In general, geothermal energy can be utilized for power generation or direct heating applications. It is regarded as an environmentally beneficial clean energy source that, when used to generate electrical power, has the potential to considerably reduce greenhouse gas (GHG) emissions. It is reported that global net electrical power demand will increase by nearly 85% between 2004 and 2030 to 30,364 TWh in 2030 from 16,424 TWh in 2004, making the use of geothermal energy for electricity generation an appealing solution, especially with advances being made in innovative technological methods of drilling and power generation schemes.

This book covers various interesting topics of research related to geothermal energy due to its significant utilization and prospects. It is the result of contributions from several researchers and experts worldwide. It is hoped that the book will be a useful source of information and basis for extended research for researchers, academics, policy makers, and practitioners in geothermal energy.

This book contains seven chapters. Chapter 1 introduces some fundamental aspects of Organic Rankine Cycle (ORC) binary-fluid power technology using low-temperature geothermal energy resources with a detailed numerical example as an illustration of its thermodynamic performance. Chapter 2 presents the geothermal energy resource in terms of the types of power plants, principle of electricity generation, and current world status of geothermal resource utilization. Chapter 3 discusses a simple technique by means of the exploration study at a field site in Eastern India. It estimates the potential of geothermal energy generated inside the Bakreswar reservoir. Chapter 4 describes the state of the art of several existing low-temperature district heating systems (LTDHs). The advantages of LTDH networks over the traditional district heating networks were discussed. Reviewed cases and studies intensified the energy efficiency potential of LTDH. This chapter suggests that this system provides a unique opportunity to integrate renewable heat sources such as geothermal and solar as much as possible.

Chapter 5 describes an approach to estimate a geothermal reservoir's productivity during active exploration and development of a geothermal prospect. This approach allows a reservoir model to be updated by overcoming the severe time limitations associated with accessing sites for drilling and well testing under snowy and mountainous conditions. Chapter 6 discusses the results of hydrogeochemical prospecting of hot springs in central northern Algeria. Finally, Chapter 7 discusses the numerical evaluation of thermal response test results in Bangkok, Thailand, and Hanoi, Vietnam. In this chapter, a moving infinite line source analytical model to evaluate the value of thermal conductivity and groundwater flow velocity is

applied. Furthermore, the five-year performance of the ground source heat pump system coupled with two vertical ground heat exchangers in Bangkok and Hanoi are evaluated.

I would like to thank all chapter authors for their efforts. I would also like to thank Author Service Manager Ms. Romina Rovan at IntechOpen for her excellent efforts in managing the publication of this book.
