Study of the hydrogen potentiality from supercritical water gasification of different biomasses: thermodynamic analysis and comparison with experimental data

Awareness of climate changes and large usage of fossil fuels have attracted more attention on the other sources of energy. Hydrogen is considered nowadays as an energy carrier of great interest. It is also used as chemical in different industrial sectors. Similarly, biomass has been taken into consideration with great interest for both energy and chemical productions, as an alternative to fossil sources: this is still a challenging topic, which industries and researchers are facing with. Several technologies have been studied for the hydrogen production from biomass. Supercritical water gasification (SCWG) is a reaction of potential interest for biomass processing, particularly for biomass characterized by a high moisture content (typically more than 50 % by weight). This technology allows to obtain a rich hydrogen gas stream, with a low CO content. The reaction takes place above the water critical point, where chemical and physical properties of water are subjected to significant changes, which affect the reactivity of the system. Different authors have studied the SCWG reaction applied to different biomass materials. In this paper an analysis of the reaction performances with different models and real biomasses is presented, comparing the results with the ones found in literature (obtained by modelling and experimental). The hydrogen potential is studied using the Gibbs free energy minimization tool available in commercial process simulators, showing a good agreement between predictions and experimental results.