The authors have tried to strike a balance between a short book chapter and a very detailed book for subject experts. There are three prime reasons behind for doing so: first, the field is quite interdisciplinary and requires simplified presentation for a person from non-parent discipline. The second reason for this short-version of a full book is that both the authors have seen students and technically oriented people, who were searching for this type of book on hydro energy. The third reason and motivation was considering engineers who are starting their career in hydro energy sector. This book is targeted to present a good starting background and basic understanding for such professionals.

Prof. Dr.-Ing. Hermann-Josef Wagner holds postgraduate and doctorate degree in electrical and mechanical engineering from the Technical University of Aachen, Germany. He is Professor for Energy Systems and Energy Economics at the Ruhr-University of Bochum, Germany. He worked as a scientist for the Juelich Research Centre, for the German Parliament and for different universities. His relevant experiences are in the fields of energy systems analysis, renewable energies like wind and water energy and life cycle analysis.

 Dr.-Ing. Jyotirmay Mathur is a mechanical engineer with a postgraduate degree in energy studies from Indian Institute of Technology, Delhi, India; and doctorate from the University of Essen, Germany. He specializes in the areas of renewable energy systems, energy policy modeling and energy efficiency in buildings. As Associate Professor in the Mechanical Engineering Department of Malaviya National Institute of Technology, Jaipur, Dr. Mathur has been the founder coordinator of the postgraduate program in energy engineering and is presently working as coordinator of the Center for Energy and Environment at his institute.