Optimization of an Industrial Area Energy Supply System With Distributed Cogeneration and Solar District Heating

Abstract

The paper presents the optimization of an energy supply system for an industrial area. The system is mainly composed of a district heating network (DHN), of a solar thermal plant with long term heat storage, of a set of combined heat and power units (CHP) and of additional thermal/cooling energy supply machines. The thermal vector can be produced by solar thermal modules, by fossil-fuel cogenerator or by conventional boilers. The optimization algorithm is based on a Mixed Integer Linear Programming (MILP) model and it has to determine the optimal structure of the energy system and the size of the components (solar field area, heat storage volume, machines sizes, etc.). The model allows to calculate the economical and environmental benefits of the solar thermal plant compared to the cogenerative production, as well as the share of the thermal demand covered by renewable energies. The aim of the paper is to identity the optimal energy production mix able to meet the user energy demands and furthermore how the solar thermal energy integration affects the optimal energy system configuration. The average costs of the heat produced for the users have been evaluated for different optimal configurations, and it emerges that the solution including some cogenerators located in strategic production units, the district heating network, the long term heat storage and a solar plant of proper size, allows achieving the lowest cost of the heat. Thus, the integrated solution turns out to be the best from both the economical and environmental point of view.