BIOMASS AND SOLAR THERMAL ENERGY IN THE SYNTHESIS AND OPTIMIZATION OF POLYGENERATION SYSTEMS

Abstract

The optimal synthesis of a polygeneration system can be obtained from information on the energy demands of the consumer center, based on the technical characteristics of the equipment and on the energy resources available. The optimal design comprehends the optimal configuration of the system to be installed as well as the optimal operation mode throughout the year, considering energy flows at market prices and utilizing the productive capacity of the installed equipment. The optimization model compares the annual economic balances for all the feasible configurations of the system through a polygeneration superstructure. A hospital located in João Pessoa, Paraíba, Brazil, was considered herein. The energy services considered were electricity, heat (hot water and laundry), steam (sterilization), and coolth (ar-conditioning). Commercially available equipment were considered, from the most conventional (diesel engines) to the least usual (absorption chillers), and renewable energy resources were included in the form of biomass and solar thermal energy. An objective function is minimized, always meeting the energy demands of the consumer center. The optimal synthesis is obtained as a result of the solution of a mixed integer linear programming model, in which the objective function was the annual cost (R$/year). For the actual scenario defined in João Pessoa, the optimal solution included the utilization of biomass as an energy resource, besides the installation of 284 flat plate solar collectors for the production of hot water, resulting in annual savings of R$ 146,867 in comparison with the traditional system. It was observed that an investment strategy that allows for slow amortizations will incentivize the use of solar collectors and biomass, with high investments in equipment, but with considerable benefits in the long term.