Thermodynamic Modeling by Entropy Maximization Applied to SCWG of Biomass: Implementation and Validation of TeS

Supercritical water gasification (SCWG) is a promising thermochemical pathway for the complete conversion of wet biomass into hydrogen-rich syngas, offering high efficiency while eliminating the need for energy-intensive drying steps. Thermodynamic modeling plays a central role in understanding equilibrium limits and optimizing operating conditions; however, the widespread reliance on commercial simulators (e.g., Aspen Plus, FactSage, GAMS) still imposes economic barriers and compromises scientific reproducibility. In this context, the present work employs TeS – Thermodynamic Equilibrium Simulation, a free and open-source Python-based software that implements a total entropy maximization (MaxS) framework grounded in non-stoichiometric elemental balancing and global enthalpy conservation to assess the equilibrium behavior of multicomponent reactive systems. Non-idealities in the fluid phase were treated using the Peng–Robinson equation of state. The MaxS model was validated against literature datasets—both experimental and simulated—for the SCWG of cellulosic materials, achieving mean absolute errors (MAE) below 4% relative to experimental results and below 2% when compared with outputs from commercial simulators under identical conditions. Computational experiments performed with the MaxS module further confirmed the technical feasibility of producing high-purity hydrogen via SCWG of sugarcane bagasse, demonstrating favorable thermochemical behavior and efficient hydrogen selectivity at equilibrium. Overall, TeS and its MaxS interface provide a robust, transparent, and reproducible platform for thermodynamic analyses of biomass SCWG, enabling accessible research and supporting the development of sustainable hydrogen and bioenergy technologies.