Energy and exergy analysis of an innovative solar system for hydrothermal carbonization process using photovoltaic solar panels

Using renewable energy is a solution to combat environmental problems; in this context, hydrothermal carbonization is an excellent method for converting biomass into solid fuels. However, this process is energyintensive. Systems utilizing parabolic trough solar collectors proposed in the literature present some limitations and challenges. Therefore, to overcome this issue, a novel conception combining photovoltaic solar panels and a batch reactor with a heating collar has been proposed. It was experimentally investigated and subjected to energy and exergy analyses. The experimental results showed that subcritical conditions (220 degrees C temperature and 40 bar pressure) were achieved. The chemical exergy of the biomass increased from 19.89 MJ/kg to 29.2 MJ/kg for the hydrochar. Due to dehydration and decarboxylation, the O/C and H/C atomic ratios decreased over time, and the hydrochar properties approximated lignite. The solar panel system achieved average energy and exergy efficiencies of 14 % and 15 %, respectively, with high thermal exergy destruction of 825.94 kWh under higher wind speeds and cell temperatures, resulting in a total entropy of 1.4 kW/K. The system's Improvement Potential ranged from 15 kW to 23 kW. The results demonstrate the feasibility of this innovative system to achieve the necessary conditions for HTC in an environmentally friendly manner.