Other technologies are pyrolysis meaning that a chemical process of decomposing biomass
to produce bio-oil in the absence of oxygen at temperature ranges of 300 - 650 C. Through thermochemical biomass gain options as direct feedstock gasification, combustion, pyrolysis or liquefaction. However, each of the processes has its own disadvantages. For example, in the gasification process there will be disadvantages such as tar yield, inefficiency in heat rate and high moisture. Some of the gasification process requires biomass with small-sized particles. The smaller the biomass size, the better would be the heat transfer. It is because the grind ability of biomass is critical to gasification process.