Obtaining biogas through the process of anaerobic fermentation is considered the most efficient method due to that it does not contribute to existing pollution, it protects the environment and brings added value to both social and economic level. Thus,"The influence of substrate processing degree on biogas yielding process" represents a contribution of the author to the enrichment of worldwide experimental researches, through the different mixtures used as substrate during testing, as well as through the analysis of the plant behavior during the comminution mechanical processing, respective mixing in liquids, simulating the mechanical process of stirring from anaerobic fermentation. Also, the book is in alignment with the innovative requirements and recommendation of the European Union regarding energetic security and independence and the exploitation of renewable sources of energy.