This e-book presents eight papers dealing with different and interesting management problems in the energy sector, from issues related to energy markets in a context of restructuring and deregulation to load forecast and unit commitment optimisation. Besides their methodological contributions these papers possess an applied, practical-oriented, problem-solving nature, which can be of help for researchers and decision-makers facing similar problems. It is hoped these papers reveal to the audience the importance and value-added of using OR models and methods to tackle in a creative and effective manner the challenging problems arising in the energy sector in order to support sound decision-making.