Thermo-economic analysis of an integrated solar thermal cycle (ISTC) using thermal storage

Solar integrated power plants are a combination of the concentrated solar power plant and thermal power plant. The thermal energy storage systems, when integrated with concentrated solar power based solar cycle, can address issues related to energy availability during non-solar hours.This study presents an integration of concentrated solar power technology based solar energy capture and storage with the 210 MW conventional Rankine cycle based thermal power plant in Dadri (India). The mathematical model of Integrated Solar Thermal Cycle (ISTC) has been developed which includes the modelling of the Linear Fresenel reflector solar system, steam power cycle, and two tank thermal storage method. Here, water and molten salt are chosen as heat transfer fiuid in the collector loops as a medium to transfer and store the solar thermal energy. A MATLAB code is used as a simulation tool to analyse the ISTC performance for different parametric variations such as temperature difference in the solar receiver, solar output, the mass flow rate of heat transfer fluids, fuel-saving ratio by varying direct normal irradiation. Based on the simulation, it is discussed that the integration of solar field with power cycle offers enhanced efficiency along with the reduction of emission of carbon dioxide. Integration of solar field with Thermal Energy Storage (TES) using two tank method with molten salt further improves the efficiency of the power cycle up to 40%. Based on results of simulations, it is discussed that ISTC using two tank method with molten salt results into the saving of large amount of fuel by replacement of one and two feed water heater(s) which ensures the recovery of the capital expenditure within approximately 10 years. Further, this improvisation contributes to environment and society by curtailing the emission of carbon dioxide drastically.