A System Design of a Solar and Geothermal Hybrid Power Plant for Flores Island

Abstract

Solar and geothermal hybrid system will be promising in the upcoming years, Flores has both energies potential. The use of diesel electric power plant (PLTD) may harmed the environment, the hybrid system with storage energy can be an alternative solution to substitute PLTD. Hence, there is an opportunity to design and implement a hybrid geothermal and solar power plant for Flores Island. Based on existing geothermal fluid characteristics in Flores Island, a hybrid power plant is designed to comprising of a single flash geothermal power generation, a solar collector system with parabolic trough collectors (PTC) either in an East-West (E-W) or a North-South (N-S) alignment, and a thermal energy storage (TES) system with synthetic oil for heat transfer fluid (HTF) and a mixture of salts for storing thermal energy. The hybrid power plant's operation is designed based on the result of the electricity load study for Flores Island. Solar energy potential for Flores Island is predicted by combining clear sky model empirical formulas and 2017-2019 sunshine duration data from local wheather station. Steady mass and energy balance analyses via Aspen HYSYS were performed to obtain electric power generation capacity for each standalone geothermal power plant and hybrid power plant. Besides, a comparison of carbon dioxide emission from the same capacity of a diesel-electric power plant, a standalone geothermal power plant, and a hybrid power plant is presented. The hybrid power plant is designed to have a solar collector system with a N-S alignment PTC system in which daily average solar irradiation is predicted to be 5.5 kWh/m2/day and a TES volume of 3,000 m3. The land area to be cleared for the solar collector system is estimated as 3.0 hectares (7.5 acres). For a steam turbine inlet pressure of 10 bar, a condenser pressure of 0.08 bar, and 1,215 operation hours per year, the hybrid power plant can produce 5,450 MWh/year of electric energy. The carbon dioxide emission reduction for standalone operation and a hybrid operation are 86% and 93%, respectively, compared to that of a PLTD.