This book is open access under a CC BY 4.0 license. This book focuses on the global cycles of energy, water and carbon, which are not only the essentials of our main energy carriers, the fossil fuels, but are also the building blocks of life. The book offers an overview of the basic scientific facts and relationships that are needed to understand today’s energy generation and use, how they relate to global climate, the water cycle and other resources, and the complexities of energy policy. Building on the work of the Desertec project, it presents the main technological options that we will have in a world after the “Energiewende” and presents the possible future solutions for a sustainable world. The book is written in an engaging, descriptive style that can be understood by those without specific knowledge of science or economics and allows readers to form their own conclusions.  Controversy rages over energy problems, climate change and their possiblesolutions. Expressions like “climate deniers”, “renaissance of nuclear energy”, “stop the war on coal”, and “Energiewende now” represent a diversity of opinions that divide our society and political leaders. This book shows the reader the whole energy picture and how it is part of the wider global problems of overpopulation and uncontrolled economies in a world of limited resources.