Super critical water gasification (SCWG) technology is suitable for wet biomasses and organic wastes. This technology takes advantage of the large amount of water in biomasses by using the water as a reaction medium, eliminating the costly feedstock-drying step. Supercritical water has a low dielectric constant close to that of organic compounds. The organic reactions under supercritical water, therefore, become more homogeneous, resulting in a higher reaction rate. The free radical condition of supercritical water also enhances the gas formation, leading to the high gas yield. As compared to conventional dry gasification,

SCWG produces a lower amount of tarry material and char as byproduct, due to the higher solubility and reactivity of the organic compounds in supercritical water. Nevertheless, because tar and char are difficult to gasify, they act as a drier to achieve complete gasification. The formation of tar and char also causes a reduction in the energy efficiency of the process by means of reactor plugging, heat exchanger fouling, and catalyst deactivation (Chuntanapum and Matsumura, 2010).