This textbook provides an introduction to the fundamentals of energy and power engineering. While the focus is primarily on the technical and scientific challenges, ecological and economic questions are also appropriately addressed. The book presents the current state of technology and future development possibilities. Specifically, it includes an overview of available energy sources (fossil, renewable, nuclear), discusses the principles of converting each type of primary energy into electricity, outlines potential environmental impacts and methods to avoid them, and provides an overview of achievable efficiencies, plant availability, and costs. The aim of the book is to enable the reader to assess the possibilities for utilizing various energy sources and to estimate the necessary efforts involved.