## 4 Discussion  
Many other researchers applied advanced exergy-based analyses and reported the application of these methods to different energy conversion systems. However, none of these publications reported the implementation of the obtained results for optimization purposes. The objective of the present work is to present a method for hybridizing an existing binary geothermal power plant (GPP) through the addition of a solar powered steam Rankine topping cycle, and to investigate the system's conventional and advanced exergy-based analyses. This hybridization method has many potential benefits relative to the previously proposed solar geothermal hybrid power plant (SGHPP) including the following. In the previous work on binary SGHPPs, solar thermal energy is directly used in the binary cycle. Commercial Parabolic Trough (PT) collectors typically operate with an outlet temperature of approximately 395 \({}^{\circ}\)C while binary GPPs typically have expander inlet temperatures of approximately 150 \({}^{\circ}\)C, and this temperature mismatch results in significant exergy destruction. Some researchers have assumed that solar thermal energy can be used to increase the expander inlet temperature beyond design conditions to increase thermal efficiencies and power output without fully considering practical limitations. However, operating a binary cycle well-in-excess of design temperatures and mass flow rates can decrease reliability if modifications to components are not made, and making modifications to components can be difficult and invalidate the binary cycle's warranty. In the present work, the hybridization of an existing binary GPP using a solar topping cycle achieves the benefits of an increased power output on summer days and geothermal resource conservation without having to modify the components or operating conditions of the binary cycle as follows. The geothermal brine is used as an intermediate HTF to thermally couple the topping and bottoming cycles. Specifically, a prescribed amount of low-temperature geothermal brine leaving the binary cycle is diverted to the condenser of the topping cycle where it is heated back to the geothermal production-well temperature and then mixed with the hot geothermal brine leaving the production well in a recirculation loop. Since the topping cycle is only powered by solar energy, it has a variable and intermittent output that peaks on sunny days in the summer when the binary cycle output is lowest. Depending on how the cycle operates, it can be mentioned that the plant consists of two sources of solar and geothermal energy. During the day both sources are involved in operating the plant simultaneously. During the night, both the solar and the Rankine cycle are eliminated and only the geothermal section is active, [PERSON] et al. [34]. The bottoming binary cycle is powered by geothermal energy and/or the heat from condensation in the solar topping cycle and, therefore, can be operated as a base load or a power plant. Heating and cooling from the binary cycle can also have a high economic value in areas without sufficient base-load capacity, such as in many emerging economies, or in areas with large penetrations of variable solar