Use of Supercritical and Subcritical Binary Models for Geothermal Power Plants and Effects of Geothermal Resource Temperature on Power Plant Design

Abstract

The power plant technology used for geothermal resources has been continuously developing. Binary power plants designed to generate power especially for middle and low enthalpy geothermal resources are rapidly increasing. In this study, a single stage binary power plant is designed under supercritical and subcritical conditions with different working fluids and then the results are compared. The optimum geothermal resource temperature for binary plants is investigated. The geothermal resource used in all models of this study is water dominated and has high non-condensable gas content. All parameters used in modeling are the same except for geothermal resource temperature. The temperature of geothermal resource is assumed varying between 155°C and 190°C. Depending on changing geothermal resource temperatures, the results of net powers and thermal efficiencies are compared. At the same time, the effects of subcritical and supercritical working conditions with different working fluid utilized are investigated and their results are presented.