| Abstract |
First geothermal power plant installed in 1904 was a process composed of atmospheric turbine, which was fed by a vapor dominated geothermal system. Later on in 1930s and 1940s, similar processes enhanced by condensers have been installed in Larderello area. First geothermal power plant based on flash process fed by water dominated systems was installed in 1958 at Wairakei, New Zealand. Afterwards in 1960s and 1970s, beside single-flash processes, double-flash processes for higher enthalpy geothermal fields have been installed and operated. In 1980s first prototype binary geothermal power plants were introduced and they were started to be widely used in 2000s. As seen from aforementioned, geothermal power plant technology has greatly improved in the last 50 years. Geothermal power plants, which are essentially thermal plants, and are operated as base-load power plants like them. They also differ from thermal plants for having lower efficiencies due to low resource temperatures. As they depend upon underground resource, they are dependent upon not only resource temperatures, but also physico-chemical properties of those resources. In this context, scaling is also a major issue to be taken into account in designing geothermal power plants. High carbon dioxide content of Turkish geothermal resources is also a major concern in power plant design. Therefore power plant type selection is a very critical and important issue. We have various geothermal resources with different temperatures in Turkey. Some of them are resources with middle enthalpies, and therefore, binary type power plants are suitable solution for them. Single and double flash processes have already been used for higher enthalpy resources in our country. In recent years, in order to increase the efficiencies of flash geothermal processes, bottoming binary and combined geothermal power plants have been introduced in the industry for higher enthalpy geothermal fields. In this study, old flash processes are compared with new combined systems; advantages and disadvantages are reported, and suitability of them for Turkish geothermal resources has been discussed and results are presented. Several solutions are considered for higher enthalpy resources. The first model is double flash process with efficiency of 10% compared with the second solution of single flash with bottoming binary model with efficiency of 12%. And the last model is combined cycle solution and its efficiency is calculated as 13%. In selection of suitable plants together with efficiencies silica scaling and high CO2 content issues are also taken into account. |