Hydrochar from winemaking industry wastes as solid biofuel: A thermal and kinetic analysis of pyrolysis and combustion

• HTC positively affects the thermal stability of hydrochar. • Hydrochar from co-HTC of VP and EGM has lower devolatilization and combustion index. • Higher fixed carbon and lower volatile and ash contents improve combustion efficiency. • Hydrochar exhibited reduced activation energy for both pyrolysis and combustion. Pyrolysis and combustion behavior of the hydrochar (HY) from co-hydrothermal carbonization (co-HTC) of vine pruning (VP) and exhausted grape marc (EGM) by using vinasse as wet catalytic vector was investigated through thermogravimetric analysis (TGA). For both raw- and co-HTC biomass, different iso -conversional methods were used for kinetic analysis, and the thermodynamic parameters were determined. Overall, even if HY exhibited a lower activation energy compared to EGM and VP during both pyrolysis and combustion, HTC has positive effects on the hydrochar’s structure, which achieved a more thermodynamically stable, structurally ordered, and energetically favorable state. The obtained kinetic and thermodynamic parameters would contribute to the development of biomass thermochemical conversion technologies and the application of hydrochar-based energy systems.