Alternative energies are a term and perhaps also a buzzword of our time. Indeed: The future of humanity depends on whether and how early it addresses the related questions if it does not want to risk a collapse of our highly complex world. In particular, renewable energy sources such as solar, ocean, and wind energy, as well as biomass utilization, could help avoid this. The present book is intended as a contribution to such an energy discussion. It has emerged from a thorough revision of a seminar at the University of Tübingen on the topic of alternative energies. W. Kremers has undertaken this extensive work, selecting from the wealth of ideas and implementations those forms of energy that can be predicted to have a certain future. In addition to the physical and technical projects, the...