Thermodynamic performance assessment of a new solar tower-geothermal combined power plant compared to the conventional solar tower power plant.

Concentrating solar power plants can be a good choice for green power generation; nevertheless, this technology has low financial profitability and energy dispatch capacities compared to those based on conventional fossil fuels. On the other side, hybridization of concentrating solar power with geothermal energy is a good option for the erection of large-scale power plants with high dispatch capacity and low investment cost, due to the large potential and geographical coincidence of geothermal resources with high solar irradiation areas. Thus, the main aim of the present paper is to investigate the hourly and annual performances of a new combined solar-geothermal power plant. This layout includes a bottoming binary geothermal power cycle that recovers the waste heat from a topping solar tower thermal power plant to generate power. In this process, both steam and organic turbines produce electrical power. By using this new design, the dispatch capacity and annual thermodynamic performances have been raised by more than 30% compared to the conventional solar tower plant. Furthermore, the increase in geothermal production well temperature will increase the dispatch capacity of this new hybrid plant up to 152 GWh annually, for a temperature of 95 °C. • The design of a new CSP-geothermal plant and its performances have been presented. • The topping layout is based on a solar tower power plant similar to Gemasolar. • The bottoming layout is based on a binary geothermal power plant working with R134a. • The optimization of the mass flow rate of the bottoming plant has been performed. [ABSTRACT FROM AUTHOR]