Assessing the Feasibility of an Integrated CLC-methanation system using dried and torrefied biomasses as a feedstock

This work numerically analyzes an innovative process layout considering a torrefaction processes followed by chemical looping combustion of biomass waste, solar hydrogen, and carbon methanation. System performances were evaluated by considering several agro-industrial residues (i.e., sugar beet pulp from sugar production, grape marc from winemaking and olive pits from olive oil production) as fuels, CuO supported on zirconia as oxygen carrier, and Ni supported on alumina as methanation catalyst. The torrefaction pre-treatment was proposed for upgrading the properties, namely heating values, moisture content as well as hydrophobicity, and storability, of the selected biomasses. To this aim, experimental runs were performed at 300 °C and 30 min in a lab-scale fixed bed reactor under an inert atmosphere of nitrogen. The study was complemented with an extensive investigation on fuel properties (i.e., ultimate analysis, proximate analysis, calorific values determination) of both the untreated and the torrefied samples, which provides useful input data for modelling their conversion processes. By considering that only electric energy from renewable sources is used, the capability of the proposed process to be used as an energy storage system was eventually assessed.