Power plant selection for medium to high enthalpy geothermal resources of Turkey

A geothermal power plant model depends on the variations not only the temperature, but also, geochemical, and physical features of resources. Most of the geothermal brines in the world and in our country contain dissolved minerals and NCGs (non-condensable gases). These minerals precipitate from the solution and non-condensable gases flash depending on the changes of temperature and pressure during production and re-injection processes. In this study, common geochemical characteristics of geothermal resources of Turkey are briefly mentioned; chemical conditions for operation and re-injection processes are discussed. Taking into account of the above features, "combined power plants" devised by a combination of single-double flash processes with atmospheric condenser and "binary" cycles are introduced. They are compared thermodynamically and economically with each other and the ones from previous studies. Power capacity and efficiency of Combined Cycle Model-2 have been found 38.13 MWe and 14.1%, respectively. Combined Cycle Model-3 with single flash atmospheric process and binary presents these figures as 37.20 MWe and 13.4%, respectively. Economically, although the previous model has a slight edge in ROR (rate of return) (27.5% over 27%) the second one should be preferred because of potential silica scaling potential problem in the first one. - Highlights: • Combined power plant designs have superiority over conventional ones both in efficiency and power production. • Economics on power plants point out similar results. • Reservoir chemistry (CO₂ content and silica scaling) largely favors the combined power plant selection.