Biomass can make a large contribution to the world's future energy requirements, this is a resource we cannot ignore. Case studies are used to illustrate step-by-step methods for calculating biomass resources and uses in modern applications, based on field work experiences, or to illustrate potentially perceived major changes or trends in a particular area. There are four case studies: First case study discussed about International bioenergy trade, which examines the development of the international biotrade in biomass for energy and its wider implications. Second case study deals with biogas use in small island communities, it is an illustration of small-scale use of traditional applications. Third case study explains in detail, how to develop biomass energy flow charts. Fourth case study deals with a major issue which shaping policy towards the use of biomass for energy in general and biofuels in particular. Finally, the chapter also deals with some major Technical barriers remains in it.