The energy value of biomass depends on its carbon and hydrogen contents, its non-combustibles and the water content. For unprocessed biomass, namely wood, residues and dung, the C and H contents are more or less constant for each group of fuels on an ash-free and moisture-free basis. Using this information, a method is given to calculate the low heat values of unprocessed biomass at different moisture and ash contents. While most wood species have an ash content of about 1%, the ash content of crop residues vary according to species from about 1 to 20%. Similarly dung varies from about 20 to 30% ash. However, moisture is the most important factor when determining the available energy. Tables and graphs are given of unprocessed biomass energy at different ash and moisture contents. Charcoal is the most important processed biomass. A method to calculate the energy value of charcoal from biomass is given. The energy values of other forms of biomass are also given. Finally, the role of biomass as a renewable energy (RE) source as well as it being an important tool to capture and reduce greenhouses gases (GHG) is discussed.
