Analysis of citrus peels-based polygeneration plant for hydrogen, heat, power and DME production: energy and exergy analysis

The energy sustainability of producing biofuel from wet bioresidues needs proper energy integration to ensure sustainable exploitation. This study analyses the potentials of combined hydrogen, heat, power, and LOHC (Liquid Organic Hydrogen Carrier) production from the residues of citrus juice production, at a factory scale. In this work, the main constituents of LOHC are DME (Dimethyl ether) and methanol. The proposed system is based on air-steam gasification and direct CO2-to-DME process, integrated with hydrogen purification and a CHP unit. The DME reactor is operated at 30 bar in the temperature range 493-533 K. A thermodynamic model, which is validated experimentally, simulates the proposed polygeneration system. In addition to the potential amount of biofuel, hydrogen production, and net power production, the energy and exergy efficiencies are analyzed. Despite the variation of LOHC yield with the temperature, the results show that the whole system's energy efficiency is not affected, while the small difference among the exergy efficiencies is negligible.