Solar Thermochemical Hybrid Trigeneration System With CO₂ Capture Using Dimethyl Ether-Fueled Chemical-Looping Combustion

In this paper, we propose a new solar-hybrid trigeneration system with dimethyl ether (DME)-fueled chemical-looping combustion and solar thermal energy at approximately 550°C. The system is investigated using the energy-utilization diagram (EUD). In this system, the concentrated solar thermal energy is utilized to drive the endothermic reduction of CoO with DME in the fuel reactor, producing solid fuel of Co and gaseous CO₂ as well as water vapor. Subsequently, the reduced metal oxide Co is transported into the air reactor to be oxidized for regeneration at 1,000 °C. The high-temperature flue gas from the air reactor is introduced into the gas turbine to generate power, and then it enters an absorption chiller with coefficient of performance (COP) of 1.2 to produce cooling. Finally, the high-temperature flue gas is used for the production of domestic hot water at 70 °C through a heat exchanger. The gaseous product from the fuel reactor consists only of CO₂ and water vapor, so CO₂ can be easily separated through the condensing method with super low extra energy penalty. As a result, the thermal efficiency of the new system is expected to be 96.7%, and the global exergy efficiency can reach 35%. Two important indicators of fuel energy saving ratio (FESR) and solar area saving ratio (SASR) are used to evaluate the performance of the system. FESR can reach 40.6% at a turbine inlet temperature of 1,000 °C, whereas SASR can reach 68.4%. A preliminary experiment is also conducted. The promising results obtained in this study provide a new approach for highly efficient use of solar thermal energy approximately 550°C and offer a possibility of simultaneously utilizing solar energy and alternative fuel for CO2 capture with low energy penalty.