The sub-chapters of the book were openly presented during the 4th Edition of the Conference for Sustainable Energy, held 6-8 November, 2014 and organized by the R&D Centre Renewable Energy Systems and Recycling at the Transilvania University of Brasov, Romania. This event was developed under the patronage of the International Federation for the Promotion of Mechanism and Machine Science (IFToMM), through the Technical Committee Sustainable Energy Systems.