Multi-objective optimization of a novel solar-based multigeneration energy system

A new multigeneration system based on an ocean thermal energy conversion system and equipped with flat plate and PV/T solar collectors, a reverse osmosis desalination unit to produce fresh water, a single effect absorption chiller and a PEM electrolyzer is proposed and thermodynamically assessed. Energy and exergy analyses are employed to determine the irreversibilities in each component and assess system performance. A multi-objective optimization method based on a fast and elitist non-dominated sorting genetic algorithm (NSGA-II) is applied to determine the best design parameters for the system. The two objective functions utilized in the optimization are the total cost rate of the system, which is the cost associated with fuel, component purchasing and environmental impact, and the system exergy efficiency. The total cost rate of the system is minimized while the cycle exergy efficiency is maximized using an evolutionary algorithm. To provide further insight, the Pareto frontier is shown for a multi-objective optimization. In addition, a closed form relation between exergy efficiency and total cost rate is derived, and a sensitivity analysis is performed to assess the effects of several design parameters on the system total exergy destruction rate, total cost rate and exergy efficiency.