Multi-objective optimization in unit sizing of a gas turbine cogeneration plant

An optimal planning method for cogeneration plants proposed earlier is extended to the case with multiple optimization criteria. Equipment capacities and utility maximum demands are determined so as to minimize both the annual total cost and the annual primary energy consumption in consideration of plants` operational strategies for energy demand requirements. This problem is considered as a multi-objective optimization one, and a discrete set of Pareto optimal solutions is derived numerically by the weighting method. Through a numerical study on a simple cycle gas turbine cogeneration plant used for district heating and cooling, a trade-off relationship between the economic and energy-saving properties is clarified.