Modeling and process optimization of hydrothermal gasification for hydrogen production: A comprehensive review

Hydrothermal gasification of biomass is an alternative method of producing hydrogen-rich syngas. Modeling and optimization of hydrothermal processes are important to evaluate the economic feasibility of the process. Furthermore, developing a mathematical model to represent the many underlying mechanisms during hydrothermal gasification could contribute to lower process expenditures, improve efficiency and provide an in-depth understanding of the process. The present study outlines different modeling and optimization strategies for hydrothermal gasification of biomass and waste materials to produce hydrogen-rich syngas. The modeling techniques (e.g. thermodynamic, kinetic and computational fluid dynamic modeling) and process optimization approaches (e.g. univariate, factorial, Taguchi, response surface methodology and mixture design of experiments) are discussed in this review comprehensively together with their merits and limitations. The knowledge gaps and prospects of modeling and optimization of hydrothermal conversion are also elucidated.