Today energy consumption and demand are growing up all over the world and most of the resources used like petroleum, natural gas, coal are not sustainable sources of energy. The combustion of these traditional energy sources creates greenhouse gases which causes global warming. The problems arising from non sustainable use of energy sources have led to increased awareness and widespread research on the accessibility of new and renewable energy resources and technologies. Biogas is one of the most efficient and effective options among the various other alternative sources of renewable energy especially for developing country like Ethiopia. This green energy technology have great contribution in economic, social, health and environmental aspects of the society which are pillars of sustainable development. Despite of its numerous advantages, the potential of biogas technology could not be fully harnessed due to various characteristics of substrates used for biogas production. Researchers have tried different techniques to enhance biogas production from various types of substrates and these techniques are reviewed in this book.