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Geothermics 38 (2009) 227–237

Contents lists available at ScienceDirect

Geothermics

journa l homepage: www.e lsev ier .com/ locate /geothermics

eothermal energy in Turkey: 2008 update

mran Serpena,∗, Niyazi Aksoyb, Tahir Öngürc, E. Didem Korkmaza

Istanbul Technical University, Petroleum and Natural Gas Engineering Department, 34469 Maslak-Istanbul, TurkeyDokuz Eylül University, Torbali Technical Vocational School of Higher Education, 35120 Torbali-Izmir, TurkeyGeosan Co. Inc., Buyukdere Str 27/7, 3438 Sisli-Istanbul, Turkey

r t i c l e i n f o

rticle history:eceived 16 July 2008ccepted 2 January 2009vailable online 31 January 2009

a b s t r a c t

Geological studies indicate that the most important geothermal systems of western Turkey are located inthe major grabens of the Menderes Metamorphic Massif, while those that are associated with local volcan-ism are more common in the central and eastern parts of the country. The present (2008) installed geother-mal power generation capacity in Turkey is about 32.65 MWe, while that of direct use projects is around795 MWt. Eleven major, high-to-medium enthalpy fields in western part of the country have 570 MWe

eywords:eothermalesource potentialower generationistrict heatinghemical products

of proven, 905 MWe of probable and 1389 MWe of possible geothermal reserves for power generation. Inspite of the complex legal issues related to the development of Turkey’s geothermal resources, their useis expected to increase in the future, particularly for electricity generation and for greenhouse heating.

© 2009 Elsevier Ltd. All rights reserved.

eothermal energy codeurkey

. Introduction

Due to availability, economic and environmental issues it isxpected that the worldwide use of oil, natural gas and coal is goingo decline in the future and that geothermal energy will play anmportant role in the replacement of those fossil fuels (Fridleifsson,001). The rise of oil and gas prices during the last 3 years hasade the development of the geothermal resources of Turkey more

conomically feasible.Geothermal exploration in Turkey started in the early 1960s.

t first, the work was focused on high-enthalpy fields for poten-ial power production; Kızıldere (Fig. 1) was discovered in 1968.he Balcova and Seferihisar, two medium-temperature geothermalelds, were found and studied in the 1960s and 1970s, respec-ively. A second high-enthalpy system, Germencik, and variousther medium-enthalpy fields, such as Salavatlı and Simav, weredentified in the 1980s.

Turkey’s low- and medium-temperature resources have yeto be thoroughly explored and evaluated. With proper explo-ation methods and investments, some might be shown to contain

igher-enthalpy fluids; geochemical data seem to support such aypothesis (Serpen, 2004; Palabiyik and Serpen, 2008).

A 17.8-MWe, single-flash power plant came on line at Kızılderen 1984. Since then, on average, it has been generating 10 MWe

∗ Corresponding author. Tel.: +90 212 285 6280; fax: +90 212 285 6263.E-mail address: serpen@itu.edu.tr (U. Serpen).

375-6505/$ – see front matter © 2009 Elsevier Ltd. All rights reserved.oi:10.1016/j.geothermics.2009.01.002

(gross). An air-cooled binary cycle power plant with a gross capac-ity of 7.35 MWe was installed at Salavatlı geothermal field in 2006.Recently, a decision was made to build a 47.4-MWe, double-flashpower plant at Aydın-Germencik; it is presently under construction.

Direct use of geothermal energy in Turkey has focused mainlyon district heating. The first of these systems came on line at thelow-temperature Gönen field in 1987. During 1991–2006 other 17heating systems were installed.

Based on these recent projects it is clear that geothermal energywill contribute significantly to Turkey’s future energy supply. Herewe will examine the present status, potential, economics, trendsand legislative aspects of Turkish geothermal energy resources andprojects.

2. Turkey’s geothermal resource potential

To substantiate the importance of geothermal energy in Turkey,we will present geo-scientific aspects of the country’s geothermalresources that are relevant to the assessment of their potential.

Turkey is located in the central part of the Alpine-HimalayanMountain Belt that began developing by the closing/shrinkingof the Tethys Ocean in the Late Mesozoic. High-mountain ridgeswere formed along the northern and southern sides of Anatolia,

while some pre-Cambrian-Paleozoic metamorphic shields (i.e. theMenderes and Central Anatolian Massifs) remained at its center.

The tectonic plate convergence and subduction history of theMenderes Metamorphic Massif (MMM) was developed based onthe data for the major flyschoidal basin and ophyolithic fields of

228 U. Serpen et al. / Geothermics 38 (2009) 227–237

Fig. 1. Location of major geothermal fields in Turkey. In the Aegean Coastal Belt: (A1) Seferihisar, (A2) Cesme, (A3) Balcova, (A4) Aliaga, (A5) Dikili-Bademli, (A6) Edremit, (A7)Tuzla, and (A8) Kestanbol; in the Western Anatolian grabens: (B1) Germencik, (B2) Aydın, (B3) Salavatlı-Sultanhisar, (B4) Kızıldere, and (B5) Denizli; (B6) Salihli-Kursunlu,Caferebeyli and Sart, (B7) Turgutlu-Urganlı, (B8) Alasehir-Kavaklıdere, (B9) Dikili-Kaynarca, (B10) and Bergama and (B11) Simav; in Central Anatolia: (C1) Afyon, (C2) Cappadocia,(C3) Kırsehir, (C4) Kozaklı, and (C5) Kızılcahamam; in Eastern Anatolia: (D1) Nemrut Caldera, (D2) Ercis-Zilan, and (D3) Diyadin; in the North Anatolian Fault Zone: (E1) Erzincan,(E2) Cerkes, (E3) Bolu, (E4) Düzce, (E5) Bursa and (E6) Gönen. NAFZ: North Anatolian Fault Zone; EAFZ: East Anatolian Fault Zone. Geothermal district-heating systems: (1)Gönen-Balıkesir, (2) Simav-Kütahya, (3) Kırsehir, (4) Kızılcahamam-Ankara, (5) Balcova-Izmir, (6) Afyon, (7) Kozaklı-Nevsehir, (8) Sandıklı-Afyon, (9) Diyadin-Agrı, (10)Salihli-Manisa, (11) Dikili-Izmir, 12 Sarayköy-Denizli, (13) Edremit-Canakkale, (14) Bigadic-Balıkesir, (15) Bergama-Izmir, (16) Kuzuluk-Sakarya, (17) Armutlu-Yalova, (18)Güre-Balıkesir, (19) Sorgun-Yozgat and (20) Yerköy-Yozgat. Geothermal greenhouses: (1) Dikili-Izmir, (2) Salihli-Manisa, (3) Turgutlu-Manisa, (4) Balcova-Izmir, (5) Kızıldere-D ıkesirD dere-D

tatSAfdatfisB

tlMffid

tplzm

tvMm

arHs

enizli, (6) Gümüsköy-Aydın, (7) Diyadin-Agrı, (8) Karacaali-Urfa, (9) Sındırgı-Balora-1 and Dora-2, Salavatlı-Aydın, (4) Gürmat, Germencik-Aydın (5) Bereket, Kızıl

he Izmir-Ankara range at its western and northwestern bound-ries. Recent tectonics associated with the westward movement ofhe Anatolian Sub-plate and related N–S extension, particularly inoutheastern Anatolia, caused by the northward push of the Afro-rabian Plate, created several major E–W oriented grabens. The

aults bounding these structures created suitable conditions foreep circulation of infiltrating meteoric waters and their heatingt depth. The tectonic forces and resulting structures are thoughto be responsible for the present high-heat flow in the MMM, andor the existence of medium-to-high-enthalpy geothermal systemsn Western Anatolia, and of the many low-to-medium enthalpyystems throughout the massif, especially in the Aegean Coastalelt.

The displacement of the Anatolian Sub-plate, and particularlyhe extensional crustal stresses in Eastern and Central Anato-ia, led to the development of vast volcanic fields between the

iocene and the Holocene. There are several hydrothermal mani-estations and some indications of high-heat flow at these volcanicelds, but their geothermal potential has not yet been studied inetail.

Finally, the northern boundary of the westward moving Ana-olian Sub-plate, i.e. the Northern Anatolian Fault Zone (NAFZ),rovides permeable flow channels for the infiltration and circu-

ation of waters within its up to 17-km deep brittle deformationones, explaining the presence of several low-enthalpy hydrother-al systems in that zone.Northwestern Anatolia and the Biga Peninsula (Fig. 2) have

ransitional characteristics between the relatively young (Miocene)olcanics, the NAFZ and the exhumation and rise of the Kazdagıetamorphic Massif; these two regions host some unique geother-al systems.

In Turkey the geothermal systems (Fig. 1) mainly follow recent

nd regional structural lines and are more frequent in regions ofecent tectonism and Tertiary volcanism and/or metamorphism.owever, while these systems differ radically between regions, sub-

tantial similarities tend to exist among those of a given region. This

and (10) Simav-Kütahya. Geothermal power plants: (1) Kızıldere-Denizli, (2 and 3)enizli and (6) Tuzla-Canakkale.

zonation also defines the suitability of conditions for the existenceof possible deep geothermal resources.

2.1. Aegean Coastal Belt

There are several similar, generally of low-to-medium temper-ature, geothermal fields in the Aegean Coastal Belt (Fig. 2), suchas Seferihisar (A1), Cesme (A2), Balcova (A3), Aliaga (A4), Dikili-Bademli (A5), Edremit (A6), Tuzla (A7) and Kestanbol (A8).

The Seferihisar geothermal system developed over normal faultsthat bound horst and graben structures. The thermal fluid is sea-water strongly diluted by shallow groundwater.

The Balcova field is located in an active, E–W trending, normal-fault zone; i.e. the Agamemnon Fault on the northern side of theSeferihisar Horst. The geothermal system is limited to the narrow,nearly vertical zone where the flysch deposits appear fragmentedlargely by faults (Serpen, 2004; Aksoy et al., 2008).

The hot waters from the Cesme system of the northern coastof the Cesme Peninsula discharge from karstic Triassic limestonesbound by normal faults. The chemical composition of these watersis very close to that of seawater (Gemici and Filiz, 2001); i.e. thesystem is connected to the Aegean Sea via karstic openings.

The Aliaga geothermal field is also located in an area of activenormal faults (Gevrek et al., 1987). The thermal fluid is heated sea-water circulating deep through these faults (Öngür, 1977). Similarly,the hot fluids at Edremit are considered to be waters that havereached large depths by flowing down the northern bounding faultsof the asymmetrical graben of the Edremit Gulf Basin (Fig. 2).

The geothermal system at Tuzla occurs on the SW border ofthe young (Lower Tertiary) Kazdag Metamorphic Massif (Fig. 2),where Miocene volcanism shaped the Biga Peninsula following two

intersecting, roughly N–S and NW–SE trending regional fracturesystems. During the Pliocene, several dacitic-rhyolitic lava domeswere emplaced along a N–S line in the geothermal field and northof it (Öngür, 1977). Thermal recharge of the Tuzla system is bydeep waters ascending through this N–S structural discontinuity,

U. Serpen et al. / Geothermics 38 (2009) 227–237 229

Fig. 2. Aegean Coastal Belt of Western Anatolia. Schematic geology of the area and location of some geothermal fields. Grabens: (B) Bayramic, (BE) Bergama, (BM) BüyükMenderes, (E) Edremit, (G) Gediz, (S) Seferihisar and (SM) Simav. Major geothermal fields: (A1) Seferihisar, (A2) Cesme, (A3) Balcova, (A4) Aliaga, (A5) Dikili-Bademli, (A6)E ltanhT 11) Si

wa

wivghvhtMmIwg

stbOt

dremit, (A7) Tuzla, (A8) Kestanbol, (B1) Germencik, (B2) Aydın, (B3) Salavatlı-Suurgutlu-Urganlı, (B8) Alasehir-Kavaklıdere, (B9) Dikili-Kaynarca, (B10) Bergama, (B

hich also explains the presence of Pliocene lava domes in therea.

The chemistry of the unusually hot (102 ◦C) Tuzla springaters is dominated by Na-Cl, and has unusual characteristics,

.e. (1) the Cl/HCO3 and Cl/SO4 ratios are higher than in otherolcanic waters (3.5 times greater than in Wairakei, New Zealand,eothermal waters); (2) the total amount of dissolved solids isigh (around 60,000 mg/l and more than 4.5 times larger than theolcanic-related waters of Ahuachapán, El Salvador; and (3) theigh chloride and low-silica contents are noteworthy. In addition,here are extensive allunitic alteration zones in the Tuzla field.

oreover, a young and fairly thick sedimentary basin, where oilight be generating, extends below the seabed west of the field.

t is very likely that the thermal fluids are derived from formationaters trapped in this sedimentary basin explaining their unusual

eochemical characteristics.Summarizing, all these low-to-medium enthalpy geothermal

ystems in the Aegean Coastal Belt have formed at the edges of tec-onic grabens. Generally, the thermal fluids are seawaters that haveeen heated by the particular thermal environment of the region.n the basis of silica geothermometry, Ilkisik (1995) calculated

he regional heat flow to be about 110 mW/m2, well above nor-

isar, (B4) Kızıldere, (B5) Denizli, (B6) Salihli-Kursunlu, Caferebeyli and Sart, (B7)mav, (E5) Bursa and (E6) Gönen.

mal values; Bal (2004) confirmed that figure by using Curie depthdata.

2.2. Menderes Metamorphic Massif and Western Anatoliangrabens

The largest (in size and output) regional heat flow anomaly inTurkey is found in the Menderes Metamorphic Massif (Serpen andMıhcakan, 1999). Several recent grabens have developed withinthe MMM, where all the geothermal fields are of medium-to-highenthalpy, with temperatures in the 120–240 ◦C range. The thermalfluids are of alkaline-bicarbonate compositions, have high-CO2 con-tents, and show evidence of water–rock interactions and mixingwith shallow waters (Özgür and Pekdeger, 1995; Vengosh et al.,2002; Özen et al., 2005).

The MMM is composed of two main units, the “Core” andthe “Cover”. The Core presents highly metamorphosed schists,

leptite gneisses, augen gneisses, metagranites, migmatites andmetagabbros. On the other hand, the Cover is composed of micas-chists, phyllites, metaquartzites, metabasites, metaleucogranites,chloritod-kyanite schists, metacarbonate and metaolistostroms; i.e.the metamorphism in the Massif is poly-phased (Erdogan, 1992).

2 ermic

ottTgattMtrt

tcfsfwdTg

ra

30 U. Serpen et al. / Geoth

The geothermal reservoirs are generally hosted in different unitsf the metamorphic basement, which typically presents gneissichrust sheets. In the grabens, some shallow reservoirs are found inhe Miocene sedimentary sequence covering the basement rocks.he accumulation of these sediments in Miocene-Lower Pliocenerabens, bound by NE–SW and NW–SE striking normal faults thatre oblique to today’s structures, is typical of the MMM areas wherehe geothermal systems are located. Other widely shared charac-eristics are the very large total vertical displacement of either the

iocene or Recent graben structures through a set of stepped faults,he existence of antithetic faults in the grabens, and the occur-ence of horst-graben sets. In summary, the geologic structure ofhe MMM geothermal fields is quite complex.

In Western Anatolia there are about 10 E–W trending grabenshat are 100–150 km long and 5–15 km wide. Thick sedimentaryolumns were deposited in continental basins bounded by N–Saults resulting from Mid-Miocene to Lower Pliocene E–W exten-ional tectonics (Yılmaz et al., 2000). The extension slowed downor a short period at the end of Lower Pliocene and the regionas denuded. The present graben systems began to form when theirection of the extension changed to N–S and speeded up again.

he E–W faults of the new grabens truncated the previous NW–SEraben faults underlying them (Seyitoglu, 2002).

Either the Miocene or post-Pliocene E–W grabens and the inter-elated very low-angle gravity detachment faults developed as

result of the uplift of the MMM. Present-day seismic activity

Fig. 3. Geology of the Cappadocian volcanic re

s 38 (2009) 227–237

(Eyidogan and Jackson, 1985) over the graben faults and detach-ment environments show that the stresses in these zones are stillhigh.

The recent thermal history of the MMM has not been sufficientlyinvestigated. During the uplift of the Massif, the rocks that had pre-viously reached thermal equilibrium were rapidly raised and werenot able to cool at equal rates. It is estimated that the continentalcrust can only attain its thermal equilibration in about 100 millionyears (Sclater et al., 1981) and accordingly the MMM could not havehad enough time to cool. There has not been any recent volcanicactivity in the MMM and the youngest magmatic intrusion is about19.5 Ma old. The ages of migmatitic products accompanying somedetachment zones are younger and change along the strike (YucelYılmaz, personal communication, May 2005).

The Germencik (B1), Aydın (B2), Salavatlı-Sultanhisar (B3),Kızıldere (B4) and Denizli (B5) geothermal fields in the BüyükMenderes Graben, the Salihli-Kursunlu, Caferebeyli and Sart (B6),Turgutlu-Urganlı (B7) and Alasehir-Kavaklıdere (B8) geothermalsystems in the Gediz Graben, the Dikili-Kaynarca (B9) and Bergama(B10) geothermal systems in the Dikili-Bergama Graben, and theSimav geothermal field (B11) in the Simav Graben (Fig. 2) are all

located within the same geological framework (JICA, 1986; Serpen,2000; Karamanderesi and Helvacı, 2003).

Most of these geothermal resources are located asymmetricallyin these faulted zones, especially in the areas where the faultsobliquely intersect the Miocene grabens; i.e. on only one flank of the

gion (modified from Toprak et al., 1994).

ermics 38 (2009) 227–237 231

ga

cipi

2

matcoflgt((

ssisrtGogoN

vbtoomi

2

moa

ettwsSmtHlht

ptt

Table 1Turkey’s geothermal resource base (in 1023 J) at 3 km depth for different temperatureranges.

Reference <100 ◦C 100–150 ◦C 150–250 ◦C >250◦C Total

to the atmosphere over the entire country (i.e. the heat flux) wasestimated using geothermal gradient data and rock thermal con-ductivities (Ahlatcı, 2005). The study indicated that the heat beingreleased amounted to 84.2 GW and that the average heat flux

U. Serpen et al. / Geoth

rabens (at the northern side of southern Büyük Menderes Grabennd at the southern side of the northern Gediz Graben).

In summary, the rapid uplift and high-erosion rate of the region’somplex upper crust created an abnormally high-heat flow. Thentense fracturing of the metamorphic rocks provided substantialermeability that helped the development of geothermal systems

n some zones.

.3. Central Anatolian geothermal fields

Due to the drift of the Anatolian Sub-plate, Central Anatolia hasoved and continues moving in a westerly direction at a rate of

bout 2 cm/year (Reilinger et al., 1997). Varying drift rates duringhe late Tertiary and the differing movements of Western Anatoliareated unusual geologic structures in Central Anatolia. Regionalblique faults, NW–SE and NE–SW extending grabens, volcanic ash-ow plateaus, and stratovolcanoes characterize the region. In thiseologic environment several geothermal systems, generally of lowemperatures and differing characteristics, developed [e.g. AfyonC1), Cappadocia (C2), Kırsehir (C3), Kozaklı (C4), KızılcahamamC5); Fig. 2].

The geothermal fields around Afyon are found in young grabens,imilar to those of Western Anatolia (Cihan et al., 2003). The heatource for these systems cannot be attributed to volcanism since its very old in this area (Mutlu and Gülec, 2005). The situation is veryimilar at Kızılcahamam. On the other hand, there are no volcanicocks around Kırsehir and Kozaklı. In these two fields one findshat the metamorphic basement is overlain by young sediments.eological and geophysical studies show that the basement consistsf metamorphic and peridotitic crustal slabs, and that there areranitic stocks at relative shallow depths (at about 5–7 km basedn the geometry of nearby volcanic collapse structures such as atevsehir; Fig. 3).

The Cappadocian volcanic fields (Fig. 1) have a number of centralolcanoes (e.g. Erciyes and Hasandag; Fig. 3) and vast areas coveredy ash flows associated with the collapse of the Nevsehir Caldera;he last products of this eruption center are less than 10,000 yearsld. The geologic conditions look very suitable for the developmentf a local high-heat flow anomaly. The existence of deep geother-al resources in this region looks promising, but has not yet been

nvestigated.

.4. Eastern Anatolian geothermal systems

Eastern Anatolian does not seem to present important geother-al fields in spite of its extensive and young volcanism. The only

nes in this large region are: Nemrut Caldera (D1), Ercis-Zilan (D2)nd Diyadin (D3), apparently all of low enthalpy (MTA, 1996).

The lack of good geothermal resources requires a geologicalxplanation. The continental crust in the region has broken up ashe Anatolian Sub-plate was displaced by the northward push ofhe Arabian Plate. This fragmentation allowed the magma to rise,hich resulted in extensive volcanic activity and the formation of

everal large central volcanoes such as Agrı, Tendürek, Aladaglar,üphan and Nemrut. There were explosive eruptions of acidic mag-as and ignimbrites, eruption of lavas of intermediate composition,

he formation of stratovolcanoes (e.g Agrı and Süphan) and ofawaiian-type shield volcanoes (e.g. Tendürek) by highly fluid basic

avas. In spite of all this volcanic activity there are no regional

eat flow anomalies, only local ones that may present small, low-emperature hydrothermal systems.

There is a need for detailed volcanological and systematic geo-hysical investigations of the volcanic structures of Eastern Anatoliao determine if there are deep geothermal resources associated withhe large central volcanoes in the region.

Class 1 Class 2 Class 3 Class 4

Roberts (1978) 1.9 0.84 0.23 0.14 3.10Serpen (2000) 1.6 0.93 0.32 – 2.85

2.5. Geothermal fields located in the North Anatolian Fault Zone

The right-lateral, strike-slip NAFZ system, Turkey’s most impor-tant tectonic feature, is a narrow belt that presents severallow-temperature geothermal fields; some typical ones are (fromeast to west; Fig. 2): Erzincan (E1), Cerkes (E2), Bolu (E3), Düzce(E4), Bursa (E5), Gönen (E6).

All rock units along the NAFZ system are fractured allowingthe deep infiltration and circulation of groundwaters. Because ofthe prevailing normal heat flow conditions maximum hot-springtemperatures are in the 30–40 ◦C range (Erisen and Öngür, 1976;Imbach, 1997). This situation changes slightly towards the west cre-ating conditions that are not very favorable for the development ofdeep and relatively high-temperature geothermal resources.

3. Geothermal energy potential of Turkey

To date, there are just some rough estimates of Turkey’s geother-mal energy potential since only a small number of geothermalsystems have been evaluated. Some subjective estimates exist,although not based on scientific studies (Öngür and Serpen, 2007).The first information on the country’s geothermal potential wasgiven by Roberts (1978) who estimated that the geothermalresource base1 was 3.10 × 1023 J, while Serpen (2000) indicated thatit was 2.85 × 1023 J (Table 1). Both estimates were computed on thebasis of heat flow data; the average atmospheric temperatures inthe different areas were used as datum. As seen in Table 1, thetwo estimates were quite similar, except for Class 4 (T > 250 ◦C).Since such high-temperature resources have not been discoveredin Turkey yet, the relatively more conservative estimate by Serpen(2000) seems to better represent actual conditions.

Serpen and Mıhcakan (1999) conducted a more comprehensivestudy of the geothermal resource base using stochastic modelingtechniques and data from heat-flow maps that had been drawnbased on geothermometer and temperature gradient information.On the basis of estimated temperatures at 3 km depth these authorsidentified the following three categories of accessible geothermalresources2 in specific areas; i.e. (1) T < 100 ◦C; (2) 100 ◦C < T > 180 ◦C;and (3) T > 180 ◦C. A Monte Carlo simulation was carried out, and theexpected accessible geothermal energy resource and convertibleenergy3 estimates were computed for each of the three categories(see Table 2). Convertible energies were estimated following theapproach used by the World Energy Council (1979) and discussedby Armstead (1989, pp. 38–39).

Recently, the heat being transferred from the ground surface

1 Geothermal resource base: total heat contained in subsurface rocks and fluidsbetween the surface and down to a specified depth (datum: 15 ◦C).

2 Accessible geothermal resources: Heat contained in subsurface rocks and fluidsbetween the surface and 3 km depth in the crust beneath a specified area (datum:mean annual temperature).

3 Convertible energy: fraction of the resource base that can be usefully extractedand is suitable for direct use or for generating electricity.

232 U. Serpen et al. / Geothermic

Table 2Convertible energy categories of Turkey (Serpen and Mıhcakan, 1999).

Temperature range Convertible energy (1021 J)

DDP

waM

ltcrs

ToliiMt

•

•

•

geoCtttfp(

cfNtMit

4

4

i(oa

p

greenhouse heating areas and the estimated thermal power beingprovided; most of these greenhouses are in Western Anatolia. Theones in operation cover more than 13 ha and some 6 ha of newgreenhouses are in the planning stage and may be built in the near

irect use (<100 ◦C) 4.9irect use (100–180 ◦C) 8.0ower generation (180–250 ◦C) 0.0013

as 109 mW/m2 (Serpen, 2006). These values for Turkey are ingreement with those of other studies (Ilkisik, 1995; Serpen andıhcakan, 1999).Table 1 shows that Turkey’s highest geothermal energy potential

ies with the Class 2 resources, which is appropriate for indus-rial direct applications and for power generation using binaryycle plants. On the other hand, there are ample low-temperatureesources (Class 1) that can be utilized in direct applications (e.g.pace and greenhouse heating, food drying, aquaculture).

Serpen et al. (2000) estimated the geothermal potential for someurkish geothermal fields with appropriate data using the method-logy suggested by Muffler and Cataldi (1978). For other fields withess available data the geothermal potential was estimated utiliz-ng stochastic basin analysis methods; further details are givenn Serpen et al. (2000). For the geothermal systems in the Büyük

enderes Graben, the simulations done by these authors indicatedhat

If only half of the structures in the basin are productive, the esti-mated accessible heat was 4.75 × 1019 J.The accessible geothermal resources for electricity productionwere 2.12 × 1018 J. When assuming a heat recovery factor of 15%,and a conversion efficiency of 10%, the estimated total electricitythat could be generated amounted to about 8.8 × 106 MWh (or3.18 × 1016 J).The estimated energy for direct applications was 3.5 × 1018 J.

Serpen et al. (2008) studied 11 medium- and high-enthalpyeothermal fields in the MMM and estimated their power gen-ration potential. Based on the approach used by the Societyf Petroleum Engineers to determine reserves and applied bylotworthy et al. (2006) to geothermal resources, we consideredhe 10 percentile as “proven”, the 50 percentile as “probable” andhe 90 percentile as “possible” reserves. Serpen et al. (2008) showedhat these 11 fields had the potential to generate electricity at theollowing power levels: 570, 905 and 1389 MWe on the basis of theirroven, probable and possible geothermal reserves, respectivelyTable 3).

The potential of deep geothermal resources associated with vol-anic systems has not been systematically investigated yet, exceptor some geological and geophysical surveys done around theevsehir Caldera in the Cappadocian region (Fig. 3). We estimate

hat there is an electricity generating potential of a few thousandWe in the Menderes Metamorphic Massif, of a few hundred MWe

n Central Anatolia, and of a few tens of MWe in the region of Qua-ernary volcanoes of Eastern Anatolia.

. Direct use of geothermal resources in Turkey

.1. District heating

At present (December 2008) nearly 6 million m2 of indoor spaces being heated using geothermal energy in 20 district systems

Table 3). The calculated thermal capacity, based on the amountf hot water delivered in 2008 and the difference between inletnd outlet temperatures, is around 395 MWt.

Unfortunately few district-heating systems in Turkey have beenroperly designed or installed. Because of inadequate corrosion

s 38 (2009) 227–237

protection some have serious water losses in their distributionloops (Toksoy and Serpen, 2001). Others because of improperhydraulic design are costly to operate. In district heating systemsusing low-enthalpy geothermal waters, such as Gönen, Edremit,Kızılcahamam, Bigadic, Sandıklı and Diyadin, the pumping costsneeded to send the hot waters to the buildings and adequatelydistribute the heat in them, are excessive. Since heating tariffs areroughly based on the space being heated [i.e. in the 7–9$/(m2-year)4

range], in many cases these fees are not sufficient to cover powercosts.

The most important problem with these district systems is thatthe hydraulic characteristics of the thermal resources have beencompletely ignored in their design. For example, in the towns ofSalihli and Gönen the existing wells cannot supply sufficient vol-ume of hot fluids to satisfy the needs of the system (Serpen, 2006).As a result the local government officials in the town of Sandıklıhad to install a coal-fired boiler to send additional hot fluids to theexisting geothermal district heating system. Similarly, in Bigadicthe temperature of the geothermal waters is raised by heating themusing natural gas. These cases have been discussed by Toksoy andSerpen (2001) and Serpen (2006).

4.2. Health spas

Turkey has many natural balneological sites with thermal watersto treat different kinds of illnesses, and the health-spa businessis thriving; about four million domestic visitors enjoy them everyyear. It was found that generally the facilities are not in good con-dition. If these sites were rebuilt and proper health services wereprovided, the spas could attract many foreign patients.

Major balneological sites are in Afyon (C1), Balcova (A3), Cesme(A2), Gönen (E6), and Kızılcahamam (C5) (Fig. 1). Cesme is thelargest and is also a popular summer resort because of its severalgeothermal manifestations. The local authorities, desiring to extendthe tourist activities over the entire year, had a 42-km long pipelineinstalled to provide 18 major hotels with thermal (about 57 ◦C)waters. Up to 62 hotels with a total capacity of 10,000 beds couldbe connected to the geothermal water pipeline, making Cesme themost important spa center in Turkey. For the time being, the totalthermal capacity at this site is 20.9 MWt. One should add that atCesme, heated seawater is also available for heating and spa pur-poses.

Another emerging spa center is in Afyon where there is ageothermal district heating system (Table 3). At present, there arethree important thermal hotels with balneological facilities, andseveral others are under construction. A major pipeline is beingplanned to supply geothermal water to all the hotels in the area,which soon might become the most important spa center of CentralAnatolia.

The amount of heat being used in Turkey’s geothermal healthspas and swimming pools is difficult to control and quantify; weestimate it to be about 220 MWt.

4.3. Greenhouse heating

Heating of greenhouses using geothermal fluids has becomevery popular in Turkey in recent years. Table 4 lists the major

future. The greenhouses are geothermally heated between 1500

4 $ = U.S. dollars.

U. Serpen et al. / Geothermics 38 (2009) 227–237 233

Table 3Turkey’s geothermal district heating (updated from Erdogmus et al., 2006).

District heating Inaugurated in (year) Tin (◦C) Tout (◦C) Q(max) (kg/s) Installed capacity (MWt) Equivalent space (×100 m2)

Gönen-Balikesir 1987 67 45 200 18.4 2,500Simav-Kütahya 1991 100 50 175 36.6 6,000Kırsehir 1994 54 49 270 5.6 1,800Kızılcahamam-Ank. 1995 70 42 150 17.6 2,600Balcova-Izmir 1996 118 60 320 77.7 21,500Afyon 1996 90 45 180 33.9 5,000Kozaklı-Nevsehir 1996 98 52 100 19.2 1,500Sandıklı-Afyon 1998 70 42 250 29.3 4,000Diyadin-Agrı 1998 65 55 200 8.4 400Salihli-Manisa 2002 80 40 150 25.1 4,000Dikili-Izmir 2008 120 60 40 10.0 150Sarayköy-Denizli 2002 125 60 100 27.2 2,500Edremit-Canakkale 2004 60 45 270 16.9 2,740Bigadic-Balıkesir 2006 80 50 80 10.0 1,000Bergama-Izmir 2006 62 40 100 10.0 200Kuzuluk-Sakarya 1994 80 40 25 11.2 500Armutlu-Yalova 2000 78 40 30 4.8 250Güre-Balıkesir 2006 62 52 200 8.5 300SY

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nd 2000 h per year; tomatoes and peppers (California Wonders)re the main crops.

Since many geothermal fluids in Turkey have elevated CO2 con-ents, this gas could be pumped into the greenhouses to fasten plantrowth. An optimal daytime CO2 concentration of 1000–1200 ppms suggested for the greenhouse air, and the greenhouses wouldonsume 3000–4000 ton/(ha-year).

As seen from Table 4, the major geothermal greenhouse com-lexes utilize 165 MWt of thermal power; taking into account themaller installations the total use could be about 180 MWt.

.4. Other direct uses

Geothermal energy is also used in Turkey for drying food andgricultural products. There is a pilot plant in the Urganlı area (B7;ig. 1), supported by TÜBITAK (Scientific and Technical Researchouncil of the Turkish Republic). This type of direct geothermal heatpplication may have significant potential in the Aegean region,ince a number of this type of projects have been a success (Serpen,005).

The major direct uses of geothermal resources in Turkey amounto about 795 MWt.

. Electricity generation using geothermal energy in Turkey

Table 5 shows existing – and soon to be installed – power plantsn Turkey; three are in operation, and another three will be on lineoon.

able 4urkey’s greenhouses heated by geothermal energy (updated from Serpen, 2006).

ocation Capacity (MWt) Area (ha)

ikili-Izmir 77.8 4.59alihli-Manisa 14.3 2.50urgulu-Manisa 15.4 1.10alcova-Izmir 10.5 1.00ızıldere-Denizli 18.8 1.58ümüsköy-Aydın 2.5 0.50iyadin-Agrı 3.1 0.024aracaali-Urfa 10.0 0.6ındırgı-Balıkesir 3.0 0.2imav-Kütahya 10.0 1.0

otal 165.4 13.09

a = 104 m2.

200 20.9 1,50040 3.3 500

394.6 58,940

5.1. Kızıldere geothermal field and power plant

The geothermal field at Kızıldere (B4; Fig. 2) was discoveredthrough a joint venture with the United Nations Development Pro-gram (UNDP) in 1968. Seventeen wells were drilled during thefollowing decade to develop and assess the capacity of the system.The field is liquid-dominated, with temperatures of 195–212 ◦C at300–800 m depth. The geothermal fluid contains about 4500 ppmof dissolved solids and 1.5–2.0% of CO2 by weight.

A power plant with a rated capacity of 15 MWe [17.8 MWe(gross)], fed by six production wells, began commercial operationin 1984. Three additional production wells were drilled 2 years laterto increase the steam supply. In 1997, a deep, 240 ◦C reservoir wasdiscovered by well R-1, which was connected to the power plant in2001. Partial reinjection (∼200 t/h vs. ∼900 t/h production) beganin 2004.

The power plant at Kızıldere is a conventional, single-flash cycleunit consisting of a main moisture separator, turbine-generator,direct-contact condenser, gas-extraction system and cooling tower.It has a double-flow turbine on the same shaft and seven reac-tion stages on both sides. The turbine exhaust is connected toa direct-contact condenser with a vertical, barometric leg wherenon-condensable gases (mainly CO2) and a small fraction of steamare accumulated. A wet cooling tower, which uses four motor-driven fans, is used to cool the condensate. Gas extraction fromthe condenser is done by a two-stage compressor (low- and high-pressure) with intercoolers (Serpen and Türkmen, 2005). The planthas been generating electricity for 24 years and has produced about

1.86 × 106 MWh of electricity to date. So far, the average annualelectricity production is 76 × 106 kWh.

Since the beginning, most of the operational problems atKızıldere are related to CaCO3 scaling in wellbores and surface

Table 5Turkey’s geothermal power generation.

Power plant Commissionedin (year)

Installed capacity(MWe)

Max. temp.(◦C)

Kızıldere-Denizli 1984 17.8 243Dora-I Salavatlı-Aydın 2006 7.35 172Bereket Enerji-Denizli 2007 7.5 145Gürmat-Germencik-Aydın 2009 47.4 232Tuzla-Canakkale 2009 7.5 171Dora-II Salavatlı-Aydın 2010 9.7 174

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nstallations (pipelines and separators). The operators of the fieldoon learned how to tackle the problem by introducing and per-orming frequent mechanical cleaning operations and using a rigquipped with a rotating wellhead blow-out preventer (Serpen andürkmen, 2005).

Installation of a bottoming binary power plant (Bereket Inc.) wasompleted at the end of 2007. The water-cooled, two-level, binary-ower plant has a net capacity of 6.35 MWe. The plant has beenesigned to operate using 145 ◦C water separated at the flash plantnd transported through a 2-km long pipeline. The temperature ofhe fluid at the outlet of the binary plant is 75 ◦C.

Initially, Bereket Inc. had planned to operate the binary plantn conjunction with a 2500-subscriber district-heating system inarayköy County (8 km away), using the waste geothermal watern an integrated way. Since that system is designed to operate at aemperature differential of 90–75 ◦C, the overlapping temperatureanges have caused heat shortage problems in the district heatingystem, and it was not possible to run the binary plant in the win-er of 2008. On the other hand, further cooling of the separatedater to 50 ◦C might have caused silica precipitation if both theistrict heating system and the power plant had run simultane-usly. No comprehensive reinjection strategy has been devised yetor the Kızıldere field that takes into account all these operatingonditions.

.2. Salavatlı-Sultanhisar geothermal field

The Salavatlı-Sultanhisar geothermal field (B3; Fig. 2) was dis-overed in the mid-1980s. Two wells, AS-1 and AS-2, were drilled in987 and 1988 to 1500 and 962 m depth, presenting temperaturesf 169.5◦ and 172.5 ◦C, respectively. On average, the thermal fluidontains 0.9% of CO2 by weight, which is similar to that in othereothermal fields located in the Büyük Menderes Graben (Serpennd Tüfekcioglu, 2003). Six more wells, ASR-1, ASR-2, AS-3, AS-4,SR-3 and ASR-4, have been drilled to 1430, 1300, 1325, 1320, 1250nd 1923 m depth, respectively.

Modular, small-scale development was chosen for the initialeld exploitation. The first project includes the 7.35 MWe gross6.5 MWe net) Dora-I power plant and producers AS-1 and ASR-2nd injector AS-2. Dora-I is an integrated, dual level, binary-powerlant that uses an air-cooled condenser because of water-supplyhortages in the area; it was commissioned in 2006. The tworoduction wells discharge at a rate of 565 ton/h and the plantenerates about 60 × 106 kWh of electricity annually.

Well ASR-1, located 2.5 km from the power plant, was originallyrilled for use as an injector. It was found to be a poor injector,ut a very good producer (over 325 ton/h), and was set-aside forhe second modular development stage, the Dora-II power plant,hich will be fed by wells AS-3 and ASR-1. The Dora II binary powerlant, with an installed capacity of 9.7 MWe (net), has recentlyeen ordered; it should start operating in 2010. A third plant, oneerhaps with a higher power output, might be on line at Salavatlı-ultanhisar by 2012.

.3. Germencik-Ömerbeyli geothermal field and power plant

The Germencik geothermal field (B1; Fig. 2) was discoveredhile drilling shallow geothermal exploration wells in the early

970s. Nine deep wells, ranging from 900 to 2000 m depth, were

ompleted in the early 1980s, with temperatures as high as 232 ◦C.

A private company has obtained permission to develop the field.n additional nine-well drilling campaign and a testing programas recently been completed, and the installation of a 47.4-MWeouble-flash power plant is proceeding; it is planned to begin com-ercial electricity production during the first half of 2009.

s 38 (2009) 227–237

5.4. Tuzla geothermal field

Tuzla is one of the fields in the Aegean Coastal Belt (A7; Fig. 2).Two relatively deep (814 and 1020 m) and two shallow wells (80and 130 m) were drilled in the 1980s and 1990s. The field presentshigher enthalpy fluids than others in the region; the maximummeasured temperature is 174 ◦C.

In 2007, a utility company started to develop the field andordered a 7.5-MWe (gross) binary-power plant. Recently, six morewells were drilled to supply hot water to the future plant, but thefluid temperatures and discharge rates were lower than expected.

5.5. Seferihisar geothermal field

Several wells, up to 2000 m deep, have been drilled at Seferihisar(A1; Fig. 2) since the early 1970s, but only three wells are presentlyavailable. They are of moderate depths and have temperatures inthe 120–153 ◦C range.

A State-owned company plans to install a power plant in thefield and began a new drilling campaign, but with little success. Awell recently completed to investigate the geothermal system hada temperature of 146 ◦C and poor fluid production characteristics.

Elsewhere in Turkey, exploration and development wells arebeing drilled in medium-enthalpy fields with the purpose of iden-tifying and characterizing other geothermal systems for possiblepower production development.

6. Chemical products

Since the Kızıldere geothermal fluid has elevated non-condensable gas content, a 40,000 ton/year capacity CO2 plant wasinitially installed as an integrated part of the Kızıldere power plant.In 1988, a second plant was added, increasing the liquid CO2 pro-duction capacity at this field to 80,000 ton/year.

Another CO2 plant, also with a capacity of 40,000 ton/year, hasrecently started operation in the Salavatlı-Sultanhisar field, andother plants will soon be installed as the Dora-II and Germencik-Ömerbeyli plants start operations. Today, more than 50% of Turkey’sCO2 demand is met by the non-condensable gas from geothermalresources.

At Canakkale-Tuzla (A7; Fig. 2) well No.1 has been flowing forabout 20 years producing about 100 ton/h of highly mineralizedgeothermal brines. Initially, 30 ton/day of industrial halite (NaCl)was extracted; subsequently, table salt was produced at a rate of9000 ton/year. Today, with the decline in salt prices, 3 ton/day ofCuSO4 are being extracted from these brines.

7. Economics of geothermal energy in Turkey

Two stochastic studies on the economics of producing electricityusing Turkey’s geothermal resources were conducted by Sayi (2005)and Korcan (2007). These authors indicated that at the time oftheir analyses, when electricity was selling at around $0.055/kWh,this type of utilization only looked marginally profitable. A recentstudy by Sener and Aksoy (2007) found the cost of electricity fromgeothermal resources in Turkey to be around $0.057/kWh, with apayback time of 7–8 years for this type of investment. Because ofhigh-oil prices and recent energy shortages, electricity prices in thecountry have tended to increase, reaching $0.05–0.12/kWh in 2007;the estimated average for 2008 is $0.095/kWh.

On the other hand, Kaygan (2008) conducted a stochasticstudy of several existing geothermal district-heating systems,which indicated that they did not appear to be profitable whenconsidering the present low-fixed-rate tariffs. Other investigations,such as the conceptual planning of the extension of the Balcova

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istrict-heating system (Toksoy et al., 2005) and of a district-eating project that would use Seferihisar-Cumalı geothermaluids, have always resulted in negative economics because of thexisting tariffs (Öztürk and Serpen, 2005).

Conversely, other direct-uses, such as greenhouse heating, lookery profitable. It costs $5 million to build a 1-ha greenhouse, withays back in 2–3 years. A power plant, which consumes roughlyhe same amount of geothermal heat, costs $12 million and the payack is around 8 years. In other words, in Turkey it may be morerofitable to go into the geothermal greenhouse business than intoower production.

. Trends of geothermal energy utilization in Turkey

Unlike the worldwide trend (Lund and Freeston, 2001; Lund etl., 2005), the utilization of heat pumps and the development ofnhanced geothermal systems (EGS) have not gained a footholdn Turkey. Not a single EGS project has yet been proposed, andeat-pump utilization is very limited, due to the high-capital costs

nvolved.We should stress that carbon credit exchange may not be feasi-

le, given the high-CO2 content of most of Turkey’s high-enthalpyeothermal resources. Moreover, Turkey has not yet signed theyoto protocol. Nevertheless, the trading of carbon-credit foreothermal activities has already started.

The private sector is showing significant interest in geother-al fields that could be developed for power generation and/or

reenhouse heating. When the recent Geothermal Code came intoorce in June 2008 (see next section), several companies applied forxploration permits.

The new trend for geothermal energy in Turkey is privatization.or example, the Kızıldere geothermal power plant is now in privateands. Six other geothermal fields under State control will soone transferred to the private sector. (The competitive bidding forhese fields was held on 14 October 2008; companies have offeredo pay almost $100 million for concessions six medium- and high-nthalpy fields. The Energy Ministry is preparing another tender forow-temperature geothermal fields; it is to be held during 2009).

. Geothermal legislation in Turkey

It is unfortunate that for a long time Turkey with its largeeothermal resources, many utilization opportunities and relevantxpertise, has not been able to harness its geothermal potentialue to lack of appropriate legislation. According to the country’sonstitution, all natural resources belong to the State, which issuesermits for their exploitation. Turkey’s geothermal resources haveeen regulated and managed using inadequate codes since the920s. Many technological developments have occurred since then,ut the codes have not been updated. In the early 1980s, geothermalesources were briefly regulated based on the country’s mining leg-slation, but due to management failures that code was abolishedSerpen, 2006).

Finally, a Geothermal Code was enacted by the Turkish Assem-ly in June 2007, but with three major drawbacks: (1) all activitiesere frozen for a year; (2) no change was made to bureaucraticrocedures such as those for obtaining consents for explorationnd exploitation, and (3) it provided opportunities for subdividingeothermal fields into different leases.

Freezing activities has hindered geothermal development at a

ost inopportune time. Now geothermal investors must deal with

hree organizations [i.e. the local government, the General Direc-orate of Mining Affairs (MIGEM), and the Directorate of Mineralesearch and Exploration (MTA)] to obtain permits to explore andevelop geothermal resources (Serpen and Öngür, 2007). Finally,

s 38 (2009) 227–237 235

dividing geothermal fields may create the type of problems seenin The Geysers (California, USA); i.e. overdevelopment of geother-mal resources that may result in future sizable power generationreductions. In the upcoming years, the situation created by the newGeothermal Code may lead to conflicts of interest and, hence, neg-atively affect the development of Turkey’s geothermal resources.

10. Concluding remarks

Turkey is rich in geothermal resources, particular in the Anato-lian region. Heat-flow studies have determined that the country’sgeothermal resource base is about 3 × 1023 J. More than 270 hotsprings have been identified (MTA, 1996, 2005) most of themrelated to low-to-medium enthalpy geothermal systems (Serpenand Mıhcakan, 1999, and Satman et al., 2007). The reserves in 11major fields of Western Anatolia may be adequate to generate about1400 MWe of electricity (Serpen et al., 2008).

Most of Turkey’s geothermal resources are characterized by theirlow-to-medium enthalpy and are more suitable for direct uses.Eleven major, high-to-medium enthalpy fields studied in west-ern Turkey have 570 MWe of proven, 905 MWe of probable and1389 MWe of possible geothermal reserves for power generation.The present capacity of direct-use projects related to geothermaldistrict and greenhouse heating, and spas is around 795 MWt.

A study of Turkey’s low-enthalpy geothermal resource potentialdone by Korkmaz et al. (2008) reveals that 17 (out of 19) district-heating systems cannot be supplied with sufficient volumes ofgeothermal fluids to satisfy their heat requirements. This is mainlythe result of ignoring the hot-fluid resource when these systemswere designed. In some cases, additional heat is provided to exist-ing geothermal district-heating systems by using fossil fuel-firedboilers.

There are many technical, economic and legislative problemshindering the development of Turkey’s geothermal (Toksoy andSerpen, 2001). The Geothermal Code issued in 2007 does notaddress any of these problems. Only a code with an “IntegratedResource Management Philosophy” (Luketina, 2000; Serpen andToksoy, 2001) may be able to do that.

At present, almost all major cities and some important towns ofTurkey have access to natural-gas pipelines. A liberalized marketresulted in competitive natural gas prices for industrial uses andfor heating. It is very cheap to connect gas to houses. At the begin-ning the connection charge was only $180, but lately companies areoffering free subscription because of competition. In contrast, thecharge to connect to a geothermal district heating system is still$2000–3000. In addition, the new owners of the gas distributionnetwork at Bursa (E5; Figs. 1 and 2) that took over the State-ownedpipeline company (Botas) have recently began an aggressive cam-paign and added 84,000 new subscribers. So, it seems that plansof having a geothermal district heating system for that town havebeen cancelled. The only chance for geothermal energy to competewith natural gas under existing marked conditions is an increase inthe cost of gas (and other fossil fuels). Unfortunately, world marketoil and gas prices have lately dropped significantly.

Until recently, the $2000–3000 collected from each subscriberwas used to finance part of the geothermal district heating projects;additional monies came from local government subsidies. The situ-ation has changed completely and now from an economical point ofview there is no reason to subscribe to a geothermal district heatingsystem; it is cheaper to use natural gas. Moreover, the distributionnetwork in a geothermal district heating system is much more com-

plex, bothersome and costly that a natural gas distribution network.

We should stress that so far not a single geothermal districtheating system in Turkey has been a financially sound project.Heating tariffs have been held artificially low to attract poten-tial subscribers, with the result that these geothermal projects

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ave never paid off (Öztürk and Serpen, 2005; Toksoy et al., 2005;aygan, 2008). Local government subsidies were not recovered,nd subscribers lost the money they had invested. Some local offi-ials have started to think about dismantling existing geothermalistrict-heating facilities and connecting natural gas to the housesor heating.

On a brighter side, local government officials are consideringllocating geothermal resources to develop and promote healthourism, which is very popular and economically attractive. Otherirect applications also have a large development potential inurkey. Since the geothermal waters contain silica and soda theyould be useful for cloth washing. The textile industry in the Aegeanegion could take advantage of it. In this context, it is interesting toemember that the silk industry in Bursa used geothermal watersor dyeing the silks in the 1800s.

Heating greenhouses using geothermal fluids has grown veryast during the last decade. Much larger projects could be on theay, especially considering that major greenhouse developers are

lready exporting their products.The future of geothermal power generation looks promising in

urkey. The present (December 2008) installed capacity is about3 MWe, and it is expected to more than double by end of 2010.urrently electricity is sold to the consumers at prices in the0.10–0.15/kWh range, making the use of geothermal resourcesery attractive. Although these projects need long investment peri-ds before cash starts flowing in, and the payback times are long,he particular situation in Turkey would make them profitable.

The 2007 Geothermal Code might create confusion and conflictsf interest in the geothermal industry. Conceptually, it is copiedrom the existing Mining Code without considering the differenceetween mining and producing geothermal energy (Serpen andngür, 2007). Mineral deposits are static while geothermal sys-

ems are dynamic and heat stored underground is transported tohe surface by fluids. The Geothermal Code imposes very heavy con-rol on investors through several government institutions possiblyreating a bureaucratic nightmare, and it lacks scientific and tech-ological bases. It also allows subdividing a given geothermal fieldith the possibility that different leases are given to various own-

rs. Such division is very dangerous since it could make the optimalanagement of the resource very difficult or even impossible.Finally, the new code adds new taxes to existing ones, which will

inder the development of some of Turkey’s geothermal resources.he new royalty imposed on corporate income will especiallympact health tourism and district heating systems (Serpen andngür, 2007). As a result, after 1 year of its implementation, chang-

ng the code is beginning to be discussed. This would be importantince presently the State has no intention and no available fundso develop Turkey’s large geothermal resources; only the privateector would be able to invest in these projects.

cknowledgements

We extend our special appreciation to Susan Hodgson for Englishditing of this article. We also thank the editorial team of Geother-ics for their careful review and helpful comments.

eferences

hlatcı, B., 2005. Estimation of Surface Thermal Energy Discharge and Heat Flux forAreal and Stratigraphic Distribution of Lithology in Turkey. Graduation Thesis.Petroleum and Natural Gas Engineering Department, Istanbul Technical Univer-

sity, Istanbul, Turkey, 45 pp. (in Turkish).

ksoy, N., Serpen, U., Filiz, S., 2008. Management of the Balcova-Narlidere geother-mal reservoir, Turkey. Geothermics 37, 444–466.

rmstead, H.C.H., 1983. Geothermal Energy: Its Past, Present, and Future Contri-bution to the Energy Needs of Man, 2nd ed. E. & F.N. Spon, London, UK, 404pp.

s 38 (2009) 227–237

Bal, A., 2004. Determination of the Heat Flow from Aeromagnetic Data in the Vicinityof Aydın-Izmir and Investigation of the Diffusion of the Heat Flow. MSc Thesis.Graduate School of Natural and Applied Sciences, Ankara University, Ankara,Turkey, 141 pp.

Cihan, M., Sarac, G., Gökce, O., 2003. Insights into biaxial extensional tectonics: anexample from the Sandıklı Graben, West Anatolia, Turkey. Geol. J. 38, 47–66.

Clotworthy, A.W., Ussher, G.N.H., Lawless, J.V., Randle, J.B., 2006. Toward an industryguideline for geothermal reserves determination. Geotherm. Resources CouncilTrans. 30, 859–866.

Erdogan, B., 1992. Problem of core-mantle boundary of Menderes Massive. In: Pro-ceedings of First International Symposium on Eastern Mediterranean Geology,Adana, Turkey. Geosound 20, 314–315.

Erdogmus, B., Toksoy, M., Ozerdem, B., Aksoy, N., 2006. Economic assessment ofgeothermal district heating systems: a case study of Balcova-Narlidere, Turkey.Energy Build. 38, 1053–1059.

Erisen, B., Öngür, T., 1976. Bursa Kenti Sıcaksu Kaynakları Hidrojeoloji Etüdü. GeneralDirectorate of Mineral Research and Exploration Unpublished MTA Report No.3297, Ankara, Turkey, 62 pp.

Eyidogan, H., Jackson, J.A., 1985. A seismological study of normal faulting in theDemirci, Alasehir and Gediz earthquakes of 1969–70 in Western Turkey: impli-cations for the nature and geometry of deformation in the continental crust. J.Geophys. Res. 81, 569–607.

Fridleifsson, I.B., 2001. Energy requirements for the next millennium. Geotherm.Resources Council Bull. 30, 139–144.

Gemici, Ü., Filiz, S., 2001. Hydrochemistry of the Cesme geothermal area in westernTurkey. J. Volcanol. Geotherm. Res. 110, 171–187.

Gevrek, A.I., Sener, M., Ercan, T., 1987. Canakkale-Tuzla jeotermal alanının hidroter-mal alterasyon etüdü ve volkanik kayacların petrolojisi. MTA Bull. 103–104,55–81.

Ilkisik, O.M., 1995. Regional heat flow in western Anatolia using silica temperatureestimates from thermal springs. Tectonophysics 244, 175–184.

Imbach, T., 1997. Geology of Mount Uludag with emphasis on the genesis of the Bursathermal waters, Northwest Anatolia. In: Schindler, C., Pfister, M. (Eds.), ActiveTectonics of Northwestern Anatolia—The Marmara Poly-Project. Hochschulver-lag AG vdf ETH, Zurich, Switzerland, pp. 239–266.

JICA, 1986. The Prefeasibility Study on the Dikili-Bergama Geothermal Develop-ment Project in the Republic of Turkey, Progress Report I. Japan InternationalCooperation Agency, Tokyo, Japan, 250 pp.

Karamanderesi, I.H., Helvacı, C., 2003. Geology and hydrothermal alteration of theAydın Salavatlı geothermal field, Western Anatolia, Turkey. Turkish J. Earth Sci.12, 175–198.

Kaygan, T., 2008. Risk Analysis for Direct Use from Low Temperature Geothermal Sys-tems. Graduation Thesis. Petroleum and Natural Gas Engineering Department,Istanbul Technical University, Istanbul, Turkey, 47 pp. (in Turkish).

Korcan, M.G., 2007. Economic Evaluation of Geothermal Investments by StochasticMethods. Graduation Thesis. Petroleum and Natural Gas Engineering Depart-ment, Istanbul Technical University, Istanbul, Turkey, 60 pp. (in Turkish).

Korkmaz, E.D.B., Serpen, U., Satman, A., 2008. Geothermal potentials of the fields uti-lized for district heating systems in Turkey. In: Proceedings of the New ZealandGeothermal Workshop & NZGA Seminar 2008, November 11–13, Taupo, NewZealand, pp. 277–282.

Luketina, K.M., 2000. New Zealand geothermal resource management—a regulatoryperspective. In: Proceedings of the 2000 World Geothermal Congress, Kyushu-Tohuku, Japan, pp. 751–756.

Lund, W.J., Freeston, D.H., 2001. World-wide direct uses of geothermal energy 2000.Geothermics 30, 29–68.

Lund, W.J., Freeston, D.H., Boyd, T.L., 2005. Direct application of geothermal energy:2005 worldwide review. Geothermics 34, 691–727.

MTA, 1996. Inventory of Geothermal Resources. General Directorate of MineralResearch and Exploration, Ankara, Turkey, 480 pp. (in Turkish).

MTA, 2005. Inventory of Geothermal Resources. General Directorate of MineralResearch and Exploration, Ankara, Turkey, 849 pp. (in Turkish).

Muffler, P., Cataldi, R., 1978. Methods for regional assessment of geothermalresources. Geothermics 7, 53–89.

Mutlu, H., Gülec, N., 2005. Chemical geothermometry and fluid-mineral equilib-ria for the Omer-Gecek Thermal Waters, Afyon Area, Turkey. In: Proceedings ofthe 2005 World Geothermal Congress, April 24–29, Antalya, Turkey, pp. 804–809.

Öngür, T., 1977. Volcanology and Geothermal Possibilities at Tuzla Geothermal Field.General Directorate of Mineral Research and Exploration Unpublished MTAReport, No. 5510, Ankara, Turkey, 38 pp. (in Turkish).

Öngür, T., Serpen, U., 2007. Illusions and realities on geothermal energy in Turkey. In:Proceedings of the Geothermal Energy Congress sponsored by the Association ofTurkish Engineers and Architects, November 21–24, Ankara, Turkey, pp. 157–168(in Turkish).

Özen, T., Tarcan, G., Gemici, Ü., 2005. Hydrogeochemical study of the selected thermaland mineral waters in Dikili Town, Izmir, Turkey. In: Proceedings of the 2005World Geothermal Congress, April 24–29, Antalya, Turkey, pp. 894–905.

Özgür, N., Pekdeger, A., 1995. Active geothermal systems in the rift zones of theMenderes Massif, western Anatolia, Turkey. In: Kharaka, Y.K., Chudayev, O.V.

(Eds.), Proceedings of 8th international Symposium on Water–Rock Interaction.Vladivostok, Russia, pp. 529–532.

Öztürk, M., Serpen, U., 2005. Economic evaluation of district heating of Seferihisarcounty with geothermal energy. Termodinamik 60, 94–106 (in Turkish).

Palabiyik, Y., Serpen, U., 2008. Geochemical assessment of Simav geothermal field,Turkey. Revista Mexicana de Ciencias Geológicas 25 (3), 408–425.

ermic

R

R

S

S

S

S

S

S

S

S

S

S

U. Serpen et al. / Geoth

eilinger, R.E., McClusky, S., Oral, M.B., King, R.W., Toksöz, M.N., Barka, A.A., Kınık, I.,Lenk, O., Sanlı, I., 1997. Global positioning system measurements of present daycrustal movements in the Arabia-Africa-Eurasia plate collision zone. J. Geophys.Res. 102, 9983–9999.

oberts, V.W., 1978. Geothermal Energy Prospects for the Next 50 Years. ElectricPower Research Institute (EPRI), Report ER-611-SR, pp. 4-1–4-10.

atman, A., Serpen, U., Korkmaz, D., 2007. An update on geothermal energy poten-tial of Turkey. In: Proceedings of the 32nd Workshop on Geothermal ReservoirEngineering, Stanford University, Stanford, CA, USA, pp. 157–165.

ayi, T., 2005. Economic Analysis of Geothermal Investments with Different Models.Graduation Thesis. Petroleum and Natural Gas Engineering Department, IstanbulTechnical University, Istanbul, Turkey, 58 pp. (in Turkish).

clater, J.G., Parsons, B., Japuart, C., 1981. Oceans and continents: similari-ties and differences in the mechanism of heat loss. J. Geophys. Res. 86,11,535–11,552.

ener, A.C., Aksoy, N., 2007. A general view on geothermal power economy. In:Proceedings of the Geothermal Energy Seminar on Electricity Production fromGeothermal Energy TESKON 2007, October 25–28, Izmir, Turkey, pp. 341–348 (InTurkish).

erpen, U., Mıhcakan, M., 1999. Heat flow and related geothermal potential of Turkey.Geotherm. Resources Council Trans. 23, 485–490.

erpen, U., 2000. Technical and Economical Evaluation of Kızıldere GeothermalReservoir. PhD Dissertation. Petroleum and Natural Gas Engineering Depart-ment, Istanbul Technical University, Istanbul, Turkey, 278 pp. (in Turkish).

erpen, U., Yamanlar, S., Karamanderesi, I.H., 2000. Estimation of geothermal poten-tial of B. Menderes Region. In: Proceedings of 2000 World Geothermal Congress,May 28–June 10, Kyushu-Tohuku, Japan, pp. 2205–2210.

erpen, U., Toksoy, M., 2001. Regional geothermal management policy in Turkey—aregulatory draft. Geotherm. Resources Council Trans. 25, 267–271.

erpen, U., Tüfekcioglu, H., 2003. Developments in Salavatlı geothermal field ofTurkey. Geotherm. Resources Council Trans. 25, 459–464.

erpen, U., 2004. Hydrogeological investigations on Balcova geothermal system inTurkey. Geothermics 33, 309–335.

s 38 (2009) 227–237 237

Serpen, U., 2005. Geothermal energy and its utilization in the World andTurkey. In: Proceedings of the 1st International Symposium and Exhibition onEnvironment-Friendly Energy Sources and Technologies, ISET2005, September5–7, Altinyunus-Cesme, Izmir, Turkey, pp. 215–223.

Serpen, U., Türkmen, N., 2005. Reassessment of Kızıldere geothermal power plantafter 20 years of exploitation. In: Proceedings of 2005 World GeothermalCongress, April 24–29, Antalya, Turkey, pp. 1315–1320.

Serpen, U., 2006. Status of geothermal energy and its utilization in Turkey. Geotherm.Resources Council Trans. 30, 683–688.

Serpen, U., Öngür, T., 2007. Considerations on the new geothermal code. In: Proceed-ings of Geothermal Energy Congress by the Association of Turkish Engineers andArchitects, November 21–24, Ankara, Turkey, pp. 51–62 (in Turkish).

Serpen, U., Korkmaz, E.D.B., Satman, A., 2008. Power generation potentials of majorgeothermal fields in Turkey. In: Proceedings of the 33rd Workshop on Geother-mal Reservoir Engineering, Stanford University, Stanford, CA, USA, pp. 134–139.

Seyitoglu, G., 2002. Extensional tectonics and related basin development in WesternTurkey, http://gsa.confex.com/gsa/2002AM/finalprogram/abstract 39303.htm.

Toksoy, M., Serpen, U., 2001. Institutional, technical and economic problems in directuse geothermal applications in Turkey. Geotherm. Resources Council Trans. 25,71–76.

Toksoy, M., Gulsen, E., Serpen, U., 2005. Conceptual planning of the extension ofBalcova district heating system. In: Proceedings of the 2005 World GeothermalCongress, April 24–29, Antalya, Turkey, pp. 2310–2317.

Toprak, V., Keller, J., Schumacher, R., 1994. Volcano-tectonic features of theCappadocian volcanic province. In: Proceedings of the IAVCE-I InternationalVolcanological Congress, Ankara-Turkey Excursion Guide: B2 Post CongressExcursion September 17–22, p. 58 p.

Vengosh, A., Helvacı, C., Karamanderesi, I.H., 2002. Geochemical constraints for theorigin of thermal waters from western Turkey. Appl. Geochem. 17, 163–183.

Yılmaz, Y., Genc, S., C., Gürer, F., Bozcu, M., Yılmaz, K., Karacik, Z., Altunkaynak, S.,Elmas, A., 2000. When did Western Anatolian grabens begin to develop? In:Bozkurt, E., Winchester, J.A., Piper, J.D.A. (Eds.), Tectonics and Magmatism inTurkey and the Surrounding Area. Geol. Soc., London, Spec. Publ., pp. 353–384.