Techno-economic analysis of evaporative cooling enhancement methods of a 21 MW air-cooled geothermal power plant

Abstract

Ambient temperature is a critical parameter for the performance of binary-type geothermal power plants with air-cooled condensers. Significant losses occur in this type of geothermal power plant's performance during summer. In this study, direct spray, ecomesh, and wetted media evaporative cooling techniques have been proposed, and they are analyzed from thermodynamics and economic perspectives for cooling the inlet air of the air-cooled condenser of an existing geothermal power plant. The results indicated that the investigated evaporative cooling methods could cause a notable increase in power plant performance. The study's findings show that wetted media, ecomesh, and direct spray systems could increase the power generation of the power plant by 4.6%, 3.8%, and 2.9% on an annual basis, respectively. Besides, the economic analysis results demonstrated that direct spray, ecomesh, and wetted media systems in the studied power plant yield an internal rate of return values of 19.85%, 14.40%, and 11.00%, respectively. Conversely, the payback period is 10.08, 13.7, and 17.5 years for direct and ecomesh spray systems and a wetted media system, respectively. Therefore, the direct spray evaporative cooling method can have a nearly 43% shorter payback time than a wetted media system for the investors. Consequently, geothermal power plants with air-cooled condensers should be investigated for possible alternative evaporative cooling systems to diminish the negative effect of ambient temperature on power generation capacities during warm days of the years to meet United Nation's Sustainable Development Goal #7 and mainly target 7.1, 7.2, and 7.3.