Traditionally, biomass had been utilized through direct combustion.
Burning biomass produces pollutants including dust and
the acid rain gases such as sulfur dioxide and nitrogen oxides but
the sulfur dioxide produced is 90% less than that is produced by
burning coal [8]. The combustion process is started by heating
the fuel above its ignition temperature in the presence of oxygen
or air. Under the influence of heat, the chemical bonds of the fuel
are cleaved [21].