Fuzzy optimization of a geothermal-solar-wind multi-energy microgrid considering energy quality

• A fuzzy optimization of a geothermal-solar-wind MEM considering energy quality is proposed. • Geothermal-solar-wind complementarities are fully exploited based on electrolytic thermos-electrochemical effects. • Exergy is introduced to understand and quantify the quality of energy carriers. • A trade-off between system economy and exergy efficiency can be achieved. The traditional multi-energy microgrid (MEM) generally focuses on optimizing the energy quantity, whereas the quality distinctions between diverse energy carriers are often overlooked. This paper aims to propose a fuzzy optimization of a geothermal-solar-wind MEM considering energy quality. In this MEM, geothermal, solar, and wind energy are converted and conditioned for electricity, thermal energy, and gas production, in which multi-energy complementarities are fully exploited based on electrolytic thermos-electrochemical effects. Exergy is introduced to understand and quantify the quality of energy carriers, which is formulated as an objective function to reduce the exergy loss rate. The proposed MEM shows a significant challenge as a result of the increasing complexity of energy couplings and intricate nature of energy-exergy objectives. The aforementioned issue is thus addressed through the implementation of fuzzy optimization to achieve a trade-off between two conflicting objectives. Simulation results show that the system operating cost can be reduced by at most 28.22% with higher operational flexibility.