May 1, 2009


Yazar : 

Geothermal Energy

            Geothermal Energy is a kind of energy, which is developed  by the help of very hot water  existing in the Earth’s core in appropriate  conditions. Geothermal" comes from the Greek words geo (earth) and therme (heat) so, geothermal means earth heat.

When mankind first met hot water springs and saw steam coming out of the earth, they were very afraid, but with this experience they also understand that the earth is hot inside. Prior to this century geothermal energy was not used to any great extent. Since population was relatively low and technology  was not developed enough, this source was mostly used for bathing rather than as sources of energy, especially in Rome. It is first used in America for heating in 1901 and Italy Lorderello for producing electiricity in 1904.

With an expanding population and the development of transport and technology, many areas with significant geothermal manifestations become more readily accessible. Today we drill wells into the geothermal reservoirs to bring the hot water to the surface. Geologists, geochemists, drillers and engineers do a lot of exploring and testing to locate underground areas that contain this geothermal water, so we'll know where to drill geothermal production wells. Then, once the hot water and/or steam travels up the wells to the surface, they can be used to generate electricity in geothermal power plants or for energy saving non-electrical purposes.

Due to increasing energy demand all countries search for new energy sources. And this situation is very important for Turkey because of limited petroleum and natural gas reserves. Geothermal Heating is about % 50-70 cheaper than Natural Gas Heating. We can understand its importance by this comparison clearly.

            Geothermal Energy in Turkey
            Turkey is in the fifth place in the world according to the geothermal  reserves. With the total geothermal heat potential in Turkey, 5 % of the electricity demand and 30 % of the heat energy demand of Turkey can be met. This equals to 14% of the total energy demand of Turkey (Turkey IV Energy Symposium). There is a high thermal tourism potential in Turkey. Moreover combining thermal tourism with the sea/sun/cultural tourism brings important economical development to the region and country. Because of these MTA gave importance to geothermal fields. Especially Denizli-Kızıldere.

Denizli – Kızıldere Geothermal Field

            Denizli-Kızıldere geothermal  project  was carried on  as  a joint venture  project with MTA and United Nations Development Programme. The field is on the road of Denizli, İzmir. It is 35 km far from Denizli (west of Denizli)  100 km far from Aydın. 

            In the first drilling operations they saw nearly 200 C hot water and steam mixture in Kızıldere field in 1968. After finishing and drilling and testing operations on Kızıldere field it is recognized that Kızıldere is suitable  for electiricity generation.

            Kızıldere is very important for Turkey  because the first greenhouse  which is heated with  geothermal energy is in Kızıldere. (6000 m2). It is constructed in  1985 and now also so many houses are heating with geothermal energy in Kızıldere. Also, the first and only operating electricity plant using geothermal energy  is in Kızıldere. Turkish Electricity Authority have installed the power plant with 20 MWe capacity in the area in 1984. The second will be constructed in a very near future in Aydın Germencik.

Because of it’s relatively low installation and operational cost as well as being more environmental friendly, in comparison to the conventional thermic and hydraulic power plants geothermal electricity production is advantageous. At present, nine of the geothermal fields of Turkey are of high enthalpy and are appropriate for the geothermal-electric energy conversion by Binary Cycle or by Flashing Cycle (Table 1).

Denizli-Kizildere (242 °C)
Aydin-Germencik-Omerbeyli (232 °C)
Canakkale-Tuzla (173 °C)
Aydin-Salavatli (171 °C) economy is doubtfull
Kutahya-Simav (162 °C) at limited conditions
Manisa-Salihli-Caferbeyli (155 °C)
Izmir-Seferihisar (153 °C)
Table 1 : Appropriate Geothermal Fields of Turkey for the geothermal-electric energy

            These are not the only topics that makes Denizli-Kızıldere Geothermal Field important. Also the  factory started production of CO2 in 1986 with a capacity of 120,000 ton/year in that field. It has another interesting property that; the reinjection explanatory well (R-1 and R-2), which is the depth of 2261 m. was drilled by MTA at 1998 and the highest reservoir temperature (242 ºC) in the metamorphic basement has been determined at R-2 in this field, also in Turkey.And also this well connected to the electricity system. This third reservoir was assumed to exist in the area by hydrogeological and chemical indications. 
How is Electricity Generated Using Geothermal Energy

In Geothermal Power Plants steam, heat or hot water from geothermal reservoirs provides the force that spins the turbine generators and produces electricity. The used geothermal water is then returned down an injection well into the reservoir to  be reheated, to maintain pressure, and sustain the reservoir.

There are three kinds of Geothermal Power Plants. The kind we build depends on the temperatures and pressures of a reservoir. These are; Dry Steam Power Plant, Flash Power Plant and Binary Power Plant.
In Denizli – Kızıldere Geothermal Field electricity is generating by a Dry Steam Power Plant. The plant operates on Single Flash with Condensing Cycle. Geothermal steam and brine mixture of about 12% quality with 150°C well head temperature and 15 bar pressure is separated to dry steam and brine at 147 °C and 3.5 bar. The dry steam is supplied to turbine which drives an electric generator and a compressor. A “dry” steam reservoir produces steam but little water. The steam is piped directly into a “dry” steam power plant to provide the force to spin the turbşne generator. The largest dry steam field in the world is The Geysers, north of San Francisko.

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