INTERNATIONAL SUMMER SCHOOL on Direct Application of Geothermal Energy

Under the auspice of the Division of Earth Sciences

THE KIMOLOS GEOTHERMAL DESALINATION PROJECT

C. Karytsas, V. Alexandrou and I. Boukis Centre for Renewable Energy Sources (CRES), 19th km Marathonos Ave, 190.09, Pikermi

ABSTRACT According to the results of this project the exploitation of low enthalpy geothermal The Kimolos Geothermal Desalination energy in the unit results in the substitution Project is concerned with the exploitation of at least 500 TOE/year [1 TOE (Tonnes of the low enthalpy geothermal potential of Oil Equivalent) = 8,000,000 kcal/h]. Kimolos island for the production of fresh Our intention in this demonstrative water through geothermal water desalina- project is to demonstrate the technology of tion, with the intent of achieving water producing clear fresh desalinated water sufficiency for the island. from low enthalpy geothermal resources Funding for the project was provided on Kimolos Isl. Further-on, we investigate by the THERMIE EU-DGXVII program the technical and financial feasibility for through contract No. GE-438-94-HE. applying and disseminating such innova- The island of Kimolos, faces pronoun- tive desalination schemes in other regions ced water scarcity problems, as other of and the EU with similar islands also do. Never- renewable energy sources potential. theless, Kimolos Isl. is fortunate enough to possess a very significant source of 1. OBJECTIVES environmentally friendly energy which is renewable and of low cost, that is the low The main objective of this project is to enthalpy geothermal energy potential. exploit part of the low enthalpy geothermal potential of Kimolos island for the The desalination method applied is production of fresh water through sea- that of Multiple-Effect Distillation (MED) water or geothermal water desalination, with distillation under vacuum in vertical with the intent of achieving water tubes. The unit will use low enthalpy geo- sufficiency for Kimolos Island inducing thermal energy (with a wellhead tem- further agricultural, industrial and tourist o perature of approximately 61 C) as the development on the island. heating and feed-water medium. The desalination method applied is the The unit, built during the period of Multiple-effect Distillation (MED) method 1998-1999 produced, in average, 3.24 with distillation under vacuum in vertical 3 m /h of fresh water, when a geothermal tubes. The unit will use low enthalpy 3 water flow-rate of 50 m /h at a wellhead geothermal energy as the heating and o temperature of 61 C was utilized. The feed-water medium. fresh water produced had a Total Dissolved Solid (TDS) content of less than Renewable Energy Source driven sea 10 ppm, according to the plant’s built-in water desalination units, such as those salinity meter. driven by low enthalpy geothermal energy, guarantee friendly to the environment, cost Several tests to measure and quantify effective and energy efficient production of the differential production of the unit took- desalinated water in regions with severe place during the monitoring period. water supply problems (such as several of Different geothermal water yields were the ), which nevertheless tested against the fresh-water production are fortunate enough to have renewable rate of the unit.

- 206 - energy resources at first hand for cene being presently exhausted, the last immediate exploitation. volcanic eruptive cycle taking place, on the The island of Kimolos, similarily to east side of the island, just 900,000 years numerous other Aegean Sea islands, ago. faces pronounced water scarcity prob- On the Northern part of Kimolos island lems. On Kimolos Isl. drinking water is the geological, geophysical, geothermal available through transportation by water and hydrogeological data all lead to the tankers from Peireus, which lies some assumption that a significant reservoir lies sixty nautical miles away and costs more at depths of 100 to 300 m within volcano- than 5,28 per cubic meter or in the form clastic and volcanic (lavas) rocks, being of bottled water at 0,44 per 1.5 litres. supplied from a system of deep faults. Water for sanitary purposes originates A NE-SW tectonic lineament with from rain collector tanks gathered from the numerous thermal springs aligned on it water rained down on the roof of the with temperatures of up to 65oC seems to houses. Rain in the Western is continue to be active. Most of the volcanic very scarce (with a rainfall less than 450 eruptive activity has been affected by this, mm rain annually). still active, lineament (Fytikas and Vougi- Nevertheless, Kimolos Isl., like other oukalakis, 1992). The existence of this islands or regions facing similar water tectonic lineament together with an older scarcity problems, is fortunate enough to one, with a NW-SE direction, allow the possess a very significant source of flow of sea-water parallel to these sys- environmentally friendly energy which is tems, cold-water descending and hotwa- renewable and of low cost, that is the low ter ascending. According to geological, enthalpy geothermal energy potential. geochemical, geophysical, volcanological With this desalination unit we intend not and geothermal data (Fytikas, 1995) it is only to minimize this water scarcity determined that the geothermal resources problem but also to induce development on Kimolos Isl. are formed by the entrap- on the island through water sufficiency. ment of ascending hot sea-water in porous Our intention in this demonstrative volcanoclastic aquifers. The main hydro- project is to demonstrate the technology of geological characteristic is the existence of produ-cing clear fresh desalinated water at least 6 aquifers isolated by imperme- from geothermal water on Kimolos Isl. In able pyroclastic material. These aquifers paral-lel we investigate the technical and are characterized by very low resistivity finan-cial feasibility for further applying and values when geoelectrical surveying is disseminating such innovative desalination performed (Tsokas, 1985 and Thanas- schemes in other regions of Greece and oulas and Tsokas, 1985). The aquifers at the EU. the depth of 20-30 m have been found to have temperatures of 40 to 45oC, at depths of 50m temperatures of over 59oC 2. GEOLOGICAL AND GEOTHERMAL and at depths of 200m bottom-hole BACKGROUND temperatures of at least 61oC. The Island of Kimolos belongs to the At greater depths (deeper than 800m), Island Volcanic Complex, which is especially in the southeastern side of the part of the Active Aegean Volcanic Arc. island, temperatures may rise over 100oC High, Medium and Low Enthalpy geother- or even higher. mal resources have been detected in the The island is covered with a plentitude Milos Island Volcanic Complex with tem- of rocks, products of extensive hydro- peratures rising on Milos Island as high as thermal alterations, in fact one of the 330oC at a depth of 1100m and with o largest and of finest quality bentonite in numerous thermal springs of up to 90 C the world lies just 2 Km from the region of on Milos and Kimolos Isl (see Map 1). Prassa (NNE region of the island). The island of Kimolos, with a surface 2 Shallow exploratory boreholes (at area of 36 km is located in the northern least 10) drilled to depths of 40m have part of the previously mentioned Milos given temperatures of up to 35oC. Island Volcanic Complex (Fytikas et al., 1984). The volcanic activity of the island Two boreholes were drilled in the regi- was manifested before the lower Pleisto- on of Prassa . The boreholes were named

207 PRASSA-1 and PRASSA-2. The technical given in the following Table 2.1. specifications of the two boreholes are

Table 2.1: Technical specifications of the Prassa-1 and Prassa-2 boreholes

PRASSA-1 PRASSA-2 Total Depth 188 m 238 m Diameter of Piping 8 5/8 ” 8 5/8 ” Piezometer 100 m 115 m Total Thickness of Aquifers 60 m 54 m Hydraulic Conductivity (k) 2.2 10-6 m/sec 0.9 10-6 m/sec Transmissivity (T) from the 0.640 m2/h 0.289 m2/h recovery pumping test Number of Aquifers 6 3 Well head Temperature 61.5 oC 49.2 oC Optimal Flow-rate 80 m3/h 30 m3/h

208 The chemical composition of the geo- a) The geothermal water has a thermal water of PRASSA-1 and PRAS- composition very similar to that of sea- SA-2 boreholes based on analyses per- water, with a slightly increased content of formed by IGMR on Oct. 1995 (537/13-10- CO2, Ca and SO4 and a decreased content 95) is provided in the following Table 2.2. of Na and Cl. A remarkable point of these analyses b) Harmful elements such as As, Pb, Zn is the similarity of the geothermal water etc. are almost not detectable and composition among the thermal springs, therefore, since the chemical composition CRES-1 exploratory borehole, PRASSA-1 of the geothermal water permits its use for and PRASSA-2 and sea-water, the only desalination. difference being a slightly higher CO2, Ca Based on the previously mentioned re- and SO4 content of the geothermal water. sults it was further decided to proceed and This is probably due to dissolution of car- carry-on with our project by utilizing the bonate rocks in the subsurface, proving geothermal energy provided from the that the previously mentioned mechanism PRASSA-1 borehole, due to it’s suitable is responsible for the formation of the well-head temperature, hydraulic charac- geothermal resources on this island. teristics and chemical composition. From all chemical analyses performed The second borehole PRASSA-2 al- on the low enthalpy geothermal water though perfect in chemical composition samples from Kimolos Isl. we obtain reser- has been abandoned due to its poor hyd- o voir temperature of approx. 64 - 78 C from raulic characteristics and rather low tem- o the SiO2 geothermometer, 108-114 C from perature. On April 1996, Geotech Ltd. the Na/K geothermometer and 169 to proceeded with further pump tests on the o 228 C from the Na-K-Ca geothermometer. PRASSA-2 borehole which lead to similar Two very important facts concerning conclusions as previously. the chemical composition of the geother- mal water of PRASSA-1 are pointed out:

Table 2.2: The chemical composition (in ppm [mg/l]) of the liquid phase of the geothermal waters of boreholes PRASSA-1 and PRASSA-2 (Samples 1c and 2c analysed by IGMR 1995) Element PRASSA-1c PRASSA-2c Ca 1,066.1 1,042.1 Mg 1,240.3 1,230.6 K 391.0 391.0 Fe 1.3 0.9 Na 10,345.5 10,115.6 Mn 0.19 0.18 Zn 1.9 1.9 Pb <0.05 <0.05 Cd <0.005 <0.005 Ba 0.05 0.03 Ni 0.02 0.12 As <0.010 <0.010 Hg <0.001 <0.001 Cr <0.05 <0.05 Al 0.275 0.080 Li 0.40 0.40 Sr 14.0 14.0

SiO2 35.0 28.0

CO2 128.0 110.0

- 209 - - HCO3 108.6 109.8 Cl- 19,217.2 18,578.9

2- SO4 3,563.8 3,568.6 - NO3 <0.5 <0.5 + NH4 <0.1 <0.1 F 0.75 0.60 B 2.75 2.75 pH 6.80 6.80 Conductivity (_S/cm) 47,986 45,965

Another scenario examined the use of to the Kimolos project, instead of the origi- PRASSA-2 as a reinjection borehole if the nally planned 3-effect desalination unit. hydraulic properties permit it, which is Another significant point concerning however doubtful due to high bento- the design of the unit is the slight differ- nitization rate of this particular borehole. ence among the geothermal water com- The final design of the Geothermal position and that of the seawater, espe-

Energy Desalination Plant, the sizing and cially Ca and SO4 content. This, according order of equipment, the manufacturing, to the desalination unit provider ALFA assembly/installation have all been based LAVAL, can be easily overcome by incre- on the following characteristics and asing the anti-scalant dosage versus the features: typical figures or even through the blen- • The well-head temperature level of the ding of two suitable anti-scalants instead geothermal water of one. • The chemical composition and, hence, Moreover, since no corrosive substan- the possibility to desalinate the very ces or gases, such as H2S, have been same geothermal water detected in the geothermal water, it is obvious that it can be freely desalinated. • The geothermal water quantity and hydraulic parameters of the aquifers Another important parameter that af- fected the optimal-final design of the plant • The water needs of the island and assisted us to proceed with the D-TU- • The technical and financial feasibility 2-1200 ALFA LAVAL unit, is that in case of • The possibility of future extension of an increase of the well-head temperature the unit’s production capability. during the development of the geothermal A very important factor that had a field (which is according to the world-wide direct effect on the size and productivity of accepted geothermal field usual practice) our unit water, and consequently on the we may expect a 3-4% rise of fresh-water o optimal and final design of the unit, was productivity per 1 C increase of well-head the level of the well-head temperature of temperature. the geothermal water. Furthermore, it may be possible in the Nevertheless, since the well-head near future to proceed with the drilling of a temperatures from PRASSA-1 finally is third borehole, PRASSA-3, in the close between vicinity of PRASSA-1 to deeper aquifers 58 and 62oC the direct consequence within the Lavas (depths larger than 160m) has been an inevitable drop in the ex- and to depths of 250-300m which pected water production rate. As a result, according to the geological-geothermal o the utilization of desalination systems facts, may be able to give over 68 C with 3 larger than 2-effect were strictly prohibited flow-rates of over 100 m /h, resulting to an due to the limits in the temperature gradi- increase of the D-TU-2-1200 fresh-water 3 ent between effects. Hence, a smaller 2- production over 5 m /h. Moreover, effect desalination unit (namely D-TU-2- according to a probable future scenario, if o 1200 Ð ALFA LAVAL DESALT) was well-head temperatures are over 70 C, it considered, manufactured and contributed would be feasible (and this has actually been taken into account) to increase the

210 size of the unit to a 3-effect by just adding 3. DISTILLATION OPERATION and properly adjusting a third effect to the PRINCIPLE existing 2-effect D-TU-2-1200 unit, The proposed MED-Vertical Tube increasing the production capacity of distillation method is based on the multi- 3 fresh-water of the plant to over 9 m /h. effect distillation rising film principle at low Another important issue, taken into evaporation temperatures (less than 70°C consideration during the design phase of -ALFA LAVAL, 1993), due to the reduced the desalination unit are the actual water pressure (almost vacuum). The rising film needs of the island. It should be noted that principle takes advantage of the fact that during winter time the permanent the inner tube surfaces are always population of the island is approximately covered with a thin film of feed water that 800 inhabitants, with water needs of prevents scale formation. The working approximately 40 to 50 m3/day, whereas principle is as follows: during the summer time the population The vapor forms a column around the and water needs doubles to 1,600 tube center which presses the feed water 3 inhabitants and 100 to 120 m /day. This against the tube surface ensuring a results to a total water demand, for both continuous thin film of water on the tube drinking and sanitary purposes, of 22,000 surfaces hereby eliminating dry spots 3 3 m /y. From this quantity 6,500 m /y or where scale may deposit. 29,5% are covered by rain-water manage- ment practices and from bottled-water, A controlled amount of sea feed water leaving a water deficit of approximately is led into the bottom of each effect and 15,500 m3/y or 42.6 m3 per day which into the tubes in the heat exchanger, 3 where the low enthalpy geothermal energy equals to a production rate of 3.55 m /h in ° 12 hours per day. in the form of hot water of less than 70 C, as the heating medium, heats it up (see The desalination unit has been Figure 1). designed to operate at this time stage in such a manner to produce with an average Part of the sea-water is evaporated rate of approximately 75 m3/day of fresh under vacuum, which is created by means water through the pumping of 60 m3/h of of water ejectors connected to each effect. geothermal water with a well head The vacuum makes it possible to lower the temperature of approximately 60 oC, see boiling temperature and thereby minimi- also Table 4.1. zing the amount of energy necessary for evaporating the feed water, and Nevertheless, as already explained, furthermore the low boiling temperature this production capacity may be easily prevents deposits of scale inside the changed by simply decreasing or increa- tubes. sing the borehole pumping capacity from 50 m3/h to 100 m3/h. The vapour generated in the first ef- fect passes a separation compartment With this planning we achieve whole where the remaining feed water droplets availability of the fresh-water production are separated from the vapour and are and provide for future modest increase of extracted with the brine. The separated the water needs or giving solution to vapour leaves the first effect and flows draught problems. The cost of the produ- through the vapour connection pipe to the ced fresh-water, since there is provision heat exchanger in the second effect, and for subsidy of up to 50% (or even higher), the vapour is now used as the heating according to the Greek Law for the medium for the second effect. Brine operational costs of desalination units extracted from the first effect is mixed with operated by municipalities, is estimated to sea feed water and is brought to 3 3 be 1,03 /m for the case of a 90 m /day evaporation by means of the heat from the unit, when subsidy to the initial investment vapour generated in the first effect. This of 80% is achieved then the price of the process is repeated in the second, third, 3 water produced falls down to 0,94 /m ). fourth etc., when these occur.

211 The vapor used for heating of the second, According to the GE/438/94/HE contract third, fourth etc. effects condenses on the the desalination unit can be designed in outside of the heat exchanger tubes, and such an innovative way so that in the case flows through the flash pipe in the bottom that the geothermal water chemical com- of the heat exchanger into the flash tank. position allows it, it will be feasible to Separated vapour from the third effect is desalinate the low enthalpy geothermal led into the condenser where it is water itself, instead of the sea-water. This condensed on the outside of the con- will result in an increase of the energy denser tubes in which sea cooling water is efficiency of the unit simultaneously dec- flowing. The condensate flow down into reasing the required capital investments the flash tank at the bottom of the and operational costs (no heat exchan- condenser. The condensate is extracted gers, no sea-water preheating etc.). from the flash tank by the freshwater pump and is pumped into the fresh-water tank. 4. THE DESALINATION PLANT

212 The desalination plant has been ins- The D-TU-2-1200 desalination unit was talled at the Prassa site in an engine-room manufactured in Denmark by ALFA erected for the purposes of the project LAVAL DESALT A/S. during the winter 1999 and the spring The productivity of the DTU-2-1200 2000. The dimensions of the engine-room desalination unit was tested, at the are 8.15m in length by 5.00 m in width by facilities of KYNDBY Power station in Den- 4.20 m in height. Within the engine-room mark, before the unit was transported to is included the well-head, the D-TU-2- Greece. 1200 distillation unit and the electrical- The basic parameters taken into con- automation panel. sideration were the rate of the production A geothermal water flow of an esti- of fresh-water versus changing parame- 0 mated well-head temperature of 60-62 C ters such geothermal (hot) water flow-rate, 3 with a flow rate of about 80 m /h is brought temperature, feed-water flow-rate and as the heating medium to the heat temperature. exchange stage of the first effect. The Table 4.1 below, shows the change of geothermal water after providing its productivity of the DTU-2-1200 unit based thermal energy from 60-620C to 530C is on variations of the geothermal water flow- divided into two streams, the first of which rate (from 50 m3/h to 80 m3/h) and well- enters to the desalination unit as the feed head temperatures (from 60 to 62oC). water (with a flow rate of 50 m3/h at 530C). The remainder of the geothermal water, The calculations are based on the which is not fed into the unit as the feed following assumptions: water, is discarded to the sea or may be a) Feed-water flow-rate 50 m3/h reinjected. Following the desalination of b) Feed-water temperature 53oC the feed water there is a stream of brine c) Seawater cooling temperature 20oC water equal to approximately 46 m3/h at approximately 320C which is also dis- d) Evaporation Temperature in second o carded to the sea. effect 40 C A second sea-water pump room exists just by the sea. This sea-water pump room 4.2. The geothermal water system has been erected to enclose the sea-water The Geothermal water system of the cooling system sea-water pump, the sea- unit consists of the PRASSA 1 borehole water filter, electrical panel and the head (which has been detailed in Chapter 2), of of the sea-water cooling system piping. the Geothermal Water Pump (GWP) and For details see Photos 1-5. of the piping which connects the borehole well-head, through the GWP, with the hot- 4.1. The D-TU-2-1200 Desalination Unit water entrance of the Desalination Unit.

Table 4.1: The change of productivity of the DTU-2-1200 unit based on changes of the geothermal water flow-rate Geothermal water Geothermal water Well-head Temperature 60 Well-head Temperature oC 62 oC

Geothermal water flow-rate Fresh water production (m3/h) (m3/h)

50 2.89 3.09

60 3.55 3.80

70 3.98 4.25

80 4.33 4.62

213 4.2.1. The geothermal water pump The sea-water cooling system consists of the following components: The geothermal water pump installed • Sea-water pump at PRASSA-1 is a multi-stage down-hole vertical shaft pump. • Sea-water filters The technical specifications of the • The supply system pipeline to the geothermal water pump are given in the desalination plant following Table 4.2. The seawater pump has a yield of 250 m3/h and pressure of 5 bar. 4.2.2. The sea-water cooling system and the sea-water and brine rejection The supply system pipeline is further system divided to three pipes which have been Sea-water is used for the unit’s cool- buried within a trench 0.5 m wide and 0.6 ing system, which is necessary to produce m deep, and covered by the excavation the vacuum in the distillation effects. The products. The pipes are plastic High sea-water is pumped from a site near the Density Polyethylene (HDPE) 125 mm in Prassa geothermal springs, where a diameter. The total pipe length from the pumping station has been built just on the sea pumping unit to the plant is 522 m sea-side (see Map 2). The distance of this (3x171m). site from the plant site is approximately According to the final design the brine 200 m. This sea-water pump room has together with the remaining geothermal been erected to enclose the sea-water water are discarded into the sea. This is cooling system, the sea-water pump, the permitted due to the chemical composition sea-water filter, electrical panel and the (very close to sea water) of both fluids and head of the sea-water cooling system their temperatures. This has been based piping. on the Environmental Impact Assessment that has been carried out for the plant.

Table 4.2: Technical specifications of the geothermal water pump

Type of pump rotor 8 KHM

Number of stages 20 Nominal Power Consumption of Motor 60 HP

Nominal Head Pressure 90 m

Capacity - Speed 100 m3/h - 1450 rpm

Water Pump Performance Rate 78-79%

Diameter of water outlet 5”

Impeller Material Seawater resistant bronze

Material of Shaft Stainless steel

Inverter 45 kW ABB

The sea-water and brine rejection 80m south-east of the site of springs and system consists of 5 pipes, each with a 150m to the south-southeast of the plant diameter of 125 mm, which discards the site. The pipes have been placed within a sea-water and brine to the sea 50m to trench 0.5 m wide and 0.6 m deep, and

- 214 - covered by the excavation products. They 125 mm and the total length of the pipes is are also HDPE pipes with a diameter of 456m (5x91m).

5. THE UNIT OPERATION For example in one instance that the geothermal production flow-rate increased The operation of the unit has proven to the level of 70 m3/h the fresh-water that the Kimolos geothermal desalination production of the unit exceeded 4.12 m3/h. unit operates in a very efficient way When the geothermal water yield fell down producing a considerable quantity of clear to 60 m3/h the fresh-water production desalinated water with a noteworthy decreased to approximately 3.63 m3/h. rational use of energy. The tests were performed in order to The unit, in average, produced 3.24 prove that the geothermal desalination unit m3/h fresh water when geothermal water fresh-water production depends largely on of 50 m3/h at 61oC was used. The the geothermal water production rate, a produced fresh water was crystal clear fact that was proven during the initial with a Total Dissolved Solid content of less monitoring stages of the unit operation. than 10 ppm, as directly measured by the A remarkable point was that even with plant’s built-in salinity meter. a water yield of only 30 m3/h the unit was Several tests to measure and quantify able to produce 1.18 m3/h of fresh-water. the differential production of the unit took- Another significant parameter which place during the monitoring period. seems to have contributed to the success Different geothermal water yields were of the project and the unit operation was tested against the fresh-water production that the well-head temperature of the rate of the unit. PRASSA-1 borehole was measured at 61

215 Ð 61.5oC, two degrees higher than the The exploitation scheme under investi- anticipated well-head temperature of 59oC, gation concerns sea water or geothermal which was employed during the optimal water desalination by the method of multi design of the unit. This improved effect distillation under vacuum [MED unit] temperature level difference, a factor with the low enthalpy geothermal water crucial for thermal distillation units working acting as the heating medium (with tem- under vacuum, has led to a significant peratures of over 55oC and up to 65oC). increase of the finally measured Several cases are investigated, depending production rate of the unit. on the final wellhead temperature of the geothermal water, and the actual 6. CONCLUSIONS freshwater demands of the island. The possibility of desalinating the geothermal The final success of this geothermal water itself is also examined. All of these application project is very crucial for the parameters are correlated with the actual local population since this island encoun- cost effectiveness of the desalination ters serious freshwater (drinking and irri- plant. gation) scarcity problems, not only during the summer Tourist period (which is very According to the results of this project pronounced) but all around the year. It the exploitation of low enthalpy geothermal should be noted that during the winter time energy in the unit results in the substitution the permanent population of the island is of at least 500 TOE/year [1 TOE (Tonnes approximately 800 inhabitants, with water Oil Equivalent) = 8,000,000 kcal/h]. needs of approximately 40 to 50 m3/day, The actual dissemination of the results whereas during the summer time the of this project will provide fresh water to population and water needs rise to at least developing regions of Greece, which face 1600 inhabitants and 100 to 120 m3/day. significant water scarcity problems, such The Geothermal Energy Desalination as Milos, , , , Plant designed, manufactured, installed, etc. The proposed utilization schemes will commissioned and operated through the exploit a friendly to the environment GE/438/94/HE innovative-demonstrative energy source, which is at the same time project is virtually just the core unit on of low energy production cost, being which the Municipality of Kimolos may capable for further application in other proceed for further development de- geothermal rich EU regions which also pending on the needs and financial face similar fresh water supply problems. feasibility, having a pronounced impact to the local population.

th REFERENCES Complex)”, 6 Congress of the Greek Geologic Society, pp. 221-237, , [in Greek]. ALFA LAVAL (1993) “The Desalt D.TU GEOTECH, (1996) “Pumping tests at PRASSA Concept”, pp.12 2 borehole”, Report for CRES, THERMIE Fytikas M., et al. (1984) “Tertiary to Quaternary GE.438.94.HE, 8 p. and Diagrams [in evolution of the volcanism in the Aegean Greek]. Region”, In: Dixon, G.E., and Robertson, I.G.M.R. (1995) “Drilling of Geothermal Bore- A.H.F. (eds), The Geological evolution of holes at Prassa Kimolos Ð Execution and the Eastern Mediterranean, Special estimation of results”, Internal Report, 38 Publication of the Geological Society No. p. [in Greek]. 17, Blackwell Scientific Publications, Oxford, pp. 687-699. Karytsas, C., (1998) “Geothermal Energy Driven Fytikas, M., (1995) “Geological-Geothermal Desalination Plants”, Geothermal Resour- survey of the region of Prassa Kimolos Isl.- ces Council Bulletin, Vol. 27., No 4. pp. Selection of the geothermal productive 111-115. borehole drilling sites”, Report for CRES, THERMIE GE.438.94.HE, 25 p. [in Louis, J., (1995) “Technical report of the geo- Greek]. physical survey at Prassa Kimolos”, Univ. Athens Report for CRES, THERMIE Fytikas, M., and Vougioukalakis, G., (1992) GE.438 94.HE, 14 p. [in Greek]. “Volcanic Structure and evolution of Kimolos and Isl., (Milos Island Thanassoulas, C., and Tsokas, G., (1985) “Geo-electrical Study of Kimolos Isl”.,

216 IGMR Internal Report, 9 p. and Tsokas, G., (1985) “Geophysical survey of the Appendices, [in Greek]. islands of Milos and Kimolos”, unpublished Doctorate Thesis, The University of Thessaloniki.

PHOTOGRAPHS

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