Biomass is one of humanity's earliest sources of energy. Traditionally, biomass has been utilized through direct combustion, and this process is still widely used in many parts of the world. Biomass thermo-chemical conversion investigations are certainly not the most important options at present; combustion is responsible for over 97% of the world's bio-energy production. Biomass combustion is a series of chemical reactions by which carbon is oxidized to carbon dioxide, and hydrogen is oxidized to water. Biomass fired domestic stoves are commonly used for space heating and cooking in the rural areas. Biomass residues are now widely used in many countries to provide centralized, medium and large-scale production of process heat for electricity production. Biomass is burned by direct combustion to produce steam, the steam turns a turbine and the turbine drives a generator, producing electricity.