Biomass gasification in near- and super-critical water: Status and prospects

The current status of biomass gasification in near- and supercritical water (SCWG) is reviewed. There are two approaches to biomass gasification in supercritical water. The first: low-temperature catalytic gasification, employs reaction temperature ranging from 350 to 600 °C, and gasifies the feedstock with the aid of metal catalysts. The second: high-temperature supercritical water gasification, employs reaction temperatures ranging from 500 to 750 °C, without catalyst or with non-metallic catalysts. Reviews are made on reaction mechanism, catalyst, and experimental results for these two approaches. Engineering technologies for SCWG gasification, and an example of process analysis are also introduced. Finally, the authors' prognostications on the future prospects of this technology are offered.