Optimization design of solar enhanced natural draft dry cooling tower

•We proposed a cost model for solar enhanced natural draft dry cooling tower.•We proposed an optimization scheme for this new cooling system.•We optimally designed one for a 50MW EGS geothermal plant as a demonstration.•Results proved its economic advantages for EGS geothermal application. This paper proposed an optimization scheme for solar enhanced natural draft dry cooling tower design, in which a detailed cost model was proposed including capital, labour, maintenance and operation costs of each component. Based on the developed cost model, the optimal design option can be identified in terms of the relatively lower annual cost and the relatively higher total extra income over the Solar Enhanced Natural Draft Dry Cooling Tower (SENDDCT) lifetime. As a case study, a SENDDCT was optimally designed to meet the cooling demand for a 50MW geothermal power plant with Engineered Geothermal System (EGS) technology. The results showed that the optimized SENDDCT not only has better cooling performance during the daytime but also is a cost effective option for EGS geothermal power plants.