Summary.- Problem Definition, Tasks, Procedure and Derivation of Recommendations for Action.- Terminological and Conceptional Foundations.- Normative Criteria for Evaluation and Decision-Making.- Towards a Sustainable Energy System - Legal Basis, Deficits and Points of Reference.- Potentials for the Sustainable Development of Energy Systems.- The Reality of Sustainability: Conflicts of Aims in the Choice of Instruments.- Strategies for Accelerating...