In the paper a multi-objective optimization of a distributed trigeneration system for an industrial area is presented. The energy users located in the area are connected by existent district heating (DH) micro-grids, than the required heat can be produced by small scale CHP systems (e.g. micro gas turbines or internal combustion engine) or by a bigger and centralized CHP plant. Conventional integration boilers also can be installed inside the factories or in a centralized plant. The trigeneration system includes a set of absorption chillers, powered by cogenerated heat, used to produce cooling energy in substitution of conventional vapour compression chillers.
The optimisation has to determine the optimal structure of the system, the size and the load of each component inside the optimal solution, taking into account also the thermal inertia of the DH network. The multi-objective optimization is based on a Mixed Integer Linear Programming (MILP) model and it takes into account as objective function a linear combination of the total annual cost (for purchasing, maintaining and operating the whole trigeneration system) and the whole CO2 emissions, associated to system operation. The model allows generating different optimal solutions by varying the relative weight of the economic and the environmental objective. In this way the Pareto Front is identified and the possible improvements in both economic and environmental terms can be highlighted.
