Multi-objective optimization of a solar-assisted cogeneration system in hot climate: An exergoeconomic and exergoenvironmental assessment

The research investigated a solar-fossil fuel cogeneration system designed to generate power, freshwater, and hydrogen and oxygen in a hot climate. The system comprises multiple components, including the Brayton cycle, heat recovery steam generator, steam turbine, parabolic trough collectors, desalination unit, organic Rankine cycle, and a polymer electrolyte membrane electrolyzer. The optimization approach employed the NSGA-II, aiming to maximize exergy efficiency while minimizing total annual cost. Comprehensive analyses, including energy, exergy, economic, environmental, exergoeconomic, and exergoenvironmental assessments, were conducted. The optimal results indicated that exergy efficiency improved with higher gas turbine inlet temperatures and air compressor pressure ratios, but declined with increasing solar water fractions. Exergoeconomic and exergoenvironmental analyses identified that DB as having the highest exergy destruction cost rate, while the CC exhibited the largest exergy destruction ecological impact rate. In contrast, the solar field demonstrated the lowest cost rate of exergy destruction and minimal ecological impact. The production costs for power, freshwater, and hydrogen–oxygen were determined to be 0.0378 $/kWh, 2.2346 $/${\text{m}}^{\text{3}}$, and 4.0139 $/kg, respectively. The corresponding ecological impact rates were 0.0206 Pts/kWh, 0.7447 Pts/${\text{m}}^{\text{3}}$, and 1.2249 Pts/kg. These findings provide a thorough overview of the system’s performance and optimization from multiple perspectives, highlighting its economic and environmental viability.