A comprehensive thermodynamic modeling and multi-objective optimization is reported of a multigeneration
energy system, based on a micro gas turbine, a dual pressure heat recovery steam generator, an
absorption chiller, an ejector refrigeration cycle, a domestic water heater and a proton exchange
membrane electrolyzer, that produces multiple commodities: power, heating, cooling, hot water and
hydrogen. Energy and exergy analyses and an environmental impact assessment are included. A multiobjective
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 study 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 insight, the Pareto frontier is shown for a multi-objective optimization. In addition,
a closed form equation for the relationship between exergy efficiency and total cost rate is derived. A sensitivity
analysis is performed to assess the effects of several design parameters on the system total exergy
destruction rate, CO2 emission and exergy efficiency.