4E analysis and multi-objective optimization of hybrid solar-biomass assisted combined cycle for power generation: A case study in Yazd, Iran

Integrated solar combined cycle power plants provide substantial environmental benefits; however, their performance is strongly influenced by the intermittent nature of solar energy, which can induce operational instability. Building on previous studies that have explored various strategies to address this limitation, the present study investigates the potential of biomass gasification as a relatively underexplored approach to mitigate solar intermittency. An innovative solar-biomass-assisted combined cycle configuration for the Yazd power plant is evaluated and optimized to enhance both operational stability and sustainability. Two configurations are considered: in the first, the plant operates in a solar-driven daytime mode and a biomass-assisted nighttime mode, with syngas produced via biomass gasification injected into the duct burner to compensate for solar unavailability. In the second configuration, the solar field and gasification unit operate concurrently during daytime to assist the power plant. A thermodynamic, exergy, exergo-economic, and pollution analysis is conducted using a numerical approach. A multi-objective optimization using the NSGA-II algorithm is applied to the second configuration. The results demonstrate that the optimized hybrid system achieves an 8.63% increase in exergy efficiency, accompanied by reductions of 6.47% in the levelized cost of electricity and 6.60% in specific CO2 emissions compared to the reference ISCC plant. These findings highlight the effectiveness of biomass-assisted hybrid configurations in improving both the efficiency and sustainability of solar combined cycle power plants under intermittent operating conditions.