Torrefaction can be divided into two groups, namely, (1) dry torrefaction and (2) wet torrefaction. Dry torrefaction is operated at temperature range between 200 and 300C, under atmospheric pressure and inert nitrogen gas atmosphere with absence of oxygen. Dry torrefaction is also known as mild pyrolysis or low temperature pyrolysis, as lower reaction temperature is used as compared with conventional pyrolysis (>400C) [74].