Multicriteria approach for the improvement of energy systems design

A procedure is suggested to help designers and operators find optimized configurations and correct operation modes for energy conversion plants according to specific targets related to energetic, economic and environmental requirements. The search for a satisfactory plant solution is based on a sequential iterative procedure matching and using the information supplied by different methods: First-Law and Second-Law Analysis, Thermoeconomic Analysis, Emergy Analysis, Life Cycle Assessment. Selected groups of “Performance Indicators” are derived from these methods and each group is employed within its own field of application, over a proper space-time scale. This procedure is not a traditional “optimization method”, which can pose some practical problems because of the very high number of variables and constraints competing with each other that not always can be quantified. With this method, the designer, beginning from a tentative preliminary configuration, is guided towards a suitable solution step by step, according to given priorities, objectives and constraints of the design and/or the operation suggested by energetic, economic or environmental concerns. The procedure is applied to a cogenerative system working in a town of Northern Italy: starting from the actual configuration and operation mode of the plant, some modifications are suggested and assessed, thus identifying the way for improving the performance under various viewpoints.