Applied Energy 135 (2014) 738–747

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Applied Energy

journal homepage: www.elsevier .com/ locate/apenergy

An approach to wave energy converter applications in Ereglion the western Black Sea coast of Turkey

http://dx.doi.org/10.1016/j.apenergy.2014.05.0530306-2619/� 2014 Elsevier Ltd. All rights reserved.

⇑ Corresponding author. Tel.: +90 (256) 212 24 16; fax: +90 (256) 214 36 53.E-mail addresses: keskinhc@yahoo.com (H. Keskin Citiroglu), asliokur1983@

hotmail.com (A. Okur).1 Tel.: +90 (543) 651 74 11; fax: +90 (372) 378 16 42.

H. Keskin Citiroglu a,⇑, A. Okur b,1

a YIKOB, Investment Monitoring and Coordination Presidency, Aydin, Turkeyb Alapli District National Education Directorate, Eregli, Zonguldak, Turkey

h i g h l i g h t s

� General information on wave energy was given.� Geological, energy consumption and pollution characteristics of Eregli was given.� Possible use of wave energy in Eregli, Zonguldak (Turkey) was investigated.� Shoreline converters seems more suited, at least in the beginning, for in Eregli.� Eregli has suitable areas for the installation of an OWC and TAPCHAN systems.

a r t i c l e i n f o

Article history:Received 3 November 2013Received in revised form 16 May 2014Accepted 22 May 2014Available online 12 June 2014

Keywords:Wave energyRenewable energyShoreline converterGeologyEregliBlack Sea

a b s t r a c t

Major renewable energy types that are natural and sustainable and do not harm the environment includewater, wind, solar, geothermal, hydrogen, oceanic, biofuel (organic fuel), wave and tidal energies. Ofthese, wave energy is a type of inexpensive and clean energy that does not require capital input andany costs except for those of initial investment and maintenance, does not release any pollutants intothe atmosphere and thus presents a huge potential. The total amount of coal consumed in Eregli onthe west coast of the Black Sea accounts for about 29% of overall coal consumption in Zonguldak.Although the heavy industry in Eregli is still dependent on fossil fuels, the satisfaction of the energy needsof even households in Eregli through renewable energy sources, mainly wave energy is of utmost impor-tance to not only build a clean and healthy environment but also to achieve a cheap energy in Eregli,where a large amount of coal is consumed. Wave energy production seems more suited, at least in thebeginning, for shoreline converters in Eregli. Eregli has suitable areas for the installation of an oscillatingwater column and tapered channel systems in terms of its geological features.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction

Energy sources can be broken into three categories: fossil fuels,renewable sources and nuclear sources. Renewable energy sourcescan also be referred to as alternative resources. Renewable energysources meet 14% of the world-wide demand [1]. As is clear fromits name, renewable energy refers to a type of energy that repeatsitself, that is to say, is renewed and will never become exhausted aslong as the world exists. Among those sources that can be cited arewater, wind, solar, geothermal, hydrogen, oceanic, biofuel (organicfuel), wind and tidal energies. As these energy types continuously

renew themselves, they never face the danger of being depletedand nor do they cause harm to the environment. In addition,renewable energy sources can be used directly or converted intoanother form of energy [2,3]. Also, renewable energy includes bio-mass, wind and solar energy applications [4]. Solar radiations areone of the basic energy sources of the world. 70% of the sun’s radi-ations falling on the earth are held by the seas. Therefore, the seasand oceans can be a good source of energy if suitable methods areemployed to harness the energy stored in them. Waves formedthrough the friction between a wind and the sea surface resultsin the wind’s energy being transported to water. As water is hea-vier than air, the energy formed by the waves is 800–1000 timesgreater than that produced by the friction between wind and air.This is why waves are also referred to as high density wind energy[5]. In Europe, intensive research and work on wave energy trans-formation got under way following the sharp increase in oil prices

Fig. 1. Wave power potential that the seas and oceans of the world present (kW/m) [8,9].

Table 1Annual renewable energy potential of Turkey [13].

Type of renewable energy Type of energy use Natural potential Technical potential Economic potential

Solar energy Electric energy (GW h) 977,000 6105 305Heat (MTEP) 80,000 500 25

Hydraulic energy Electric energy (GW h) 430 215 124.5

Wind energy Terrestrial wind energy Electric energy (GW h) 400 110 50Marine wind energy Electric energy (GW h) – 180 –Sea wave energy Electric energy (GW h) 150 18 –

Geothermal energy Electric energy (GW h) – – 1.4Heat (MTEP) 31,500 7500 2843

Biomass energy Fuel (conventional MTEP) 30 10 7Fuel (modern MTEP) 90 40 25

H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747 739

in 1973. Certain European countries considered exploitable waveenergy sources to be a potential power supply and put forwardsupport measures and relevant programmes. Since many stateand privately funded research programmes were initiated, someEuropean countries such as Norway, Sweden, Denmark and partic-ularly England, Portugal and Ireland have aimed to develop waveenergy conversion technologies that can be operated industriallyin the medium and long run [6]. The first commercial wave powerplant Limpet 500 was built on the isle of Islay in Scotland in 2000and it has supplied electricity to the UK power distribution gridsince November 2000. Limpet 500 power plant with a capacity of0.5 MW was designed by Wavegen using an oscillatory water col-umn to be installed on abandoned shores [7]. More than 1000 waveenergy conversion patents have been granted in Japan, NorthAmerica and Europe [6]. Fig. 1 gives the potential of wave powerstored in the seas and oceans of the world.

The coastline of Turkey is approximately 8210 km with theexception of that of the Marmara region. A mere 1/5 of this canbe used for electricity production due to fishing, tourism and othercoastal activities [10]. The wave energy potential is presented bythis ratio of Turkish coasts is estimated to be 18.5 billion kW h[11]. This corresponds to about 13% of Turkey’s energy demand[12]. It follows that the wave energy potential along the Turkishcoast can be utilized to meet the electricity demand [11]. The mostefficient region in terms of wave formations in the seas of Turkeyand the qualities these waves have is the Black Sea coastline. Thoseregions in Turkey should be identified which present the potentialfor renewable energy and where this energy can be readily put intouse, and the values of potential energy occurring in these regionsshould be calculated and investments should be made in suitableregions in the soonest possible time [9].

A review of the energy profile of Turkey makes the role andimportance of renewable energy sources clearly seen (Table 1).However, renewable energy sources are used to quite a smallextent. It is observed that energy sources of fossil origin accounts

for nearly half of the primary energy production. Coal accountsfor 47% of electric energy production in Turkey, oil and naturalgas 15%, hydraulic and geothermal sources 13%, non-commercialfuels 23% and the other renewable fuels about 2% [13].

As the coasts of Turkey are densely populated, wave powerplants would locate in the same place as that of energy consump-tion. This would provide huge gains in energy transmission costs.Wave energy plants would be connected to the national power gridand, at times when energy production is at the highest level, theexisting hydroelectric power plants would be disconnected andbe held in reserve. Since electric energy that would be producedby wave power plants, it would be preferred over other fuels,forests would be preserved and expand, thus improving airquality [14].

2. Systems employed in wave energy production

The method used in the production of wave energy is as fol-lows; storing the force created by the Archimedes’ principle andgravity as a potential energy and balancing the energy impartedby waves with the stored energy and thus obtaining linear energyfollowed by converting this energy into electrical energy by usingpresent technologies.

2.1. Closed cycle systems

In closed cycle systems, when a special fluid meets with hotwater, it vaporizes and drives the steam turbine. After that, thesteam meets the cold water at the bottom and condenses again.This process repeats itself in a cyclic manner. In order for this sys-tem to operate well, there must be a temperature difference of20 �C between the surface and water at a depth of 1000 m. More-over, the water in the cycle pipes must have a flow rate of 48 m3.

740 H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747

Another challenge is the necessity to use pipes 300–400 m inlength and 2.5 m in diameter [14].

2.2. Open cycle systems

Open cycle systems use water in place of a special fluid. As seawater has a high boiling point, the external pressure is reduced suf-ficiently to achieve boiling at low temperatures. Similarly, thepressure is changed to realize the condensation process as well.The amount of water that is vaporized for these changes of stateto occur is 1500 m3 per 1 MW. This means fresh water yield. Thisfeature is the greatest advantage of the system [14].

3. Wave energy conversion technologies

Wave energy conversion technologies falls into three groups;those applied in regions along, close to and away from shores.The height and period of waves formed are factors that determinethe amount of wave energy to be produced. Therefore, there hasbeen a sharp increase in studies conducted to produce waveenergy.

3.1. Shoreline converters

In these applications, energy producing installations aremounted on or buried under shores. They are easier to build andmaintain compared to other converters. In addition, they do notrequire deep water connections and long underwater cables. Onthe other hand, due to the wave regime with less power, relativelya small amount of wave energy can be produced. These convertersare prevented from becoming widespread by such factors as shore-line geology, tide levels and concerns for shore protection.

3.1.1. Oscillating water column (OWC)These are partially submerged structures below sea level that

are made of steel or concrete and extend into the sea. This systemincorporates a water column and an air column above it. When thesystem is hit by waves, the water column rises and lowers, whichin turn causes the air column to become pressurized or the pres-sure in it to be relieved depending on the position of water column.The compressed air is transferred to the turbine which drives theelectric generator. Thus, the system produces energy and theenergy produced in this way is used to generate electricity [15].

3.1.2. Tapered channel system (TAPCHAN)This system is an adaptation of the conventional hydroelectric

energy production system. These systems have wall height of 3–5 m above sea level and consist of a tapering channel which feedsinto a reservoir constructed on the edge of a cliff. The narrowing ofthe channel causes the wave height to increase and the risingwaves spill over the walls of the channel into the reservoir. Asthe water is stored in the reservoir, the kinetic energy of the mov-ing waves is converted into potential energy. The stored water isfed through a turbine. Since the system has few moving parts, ithas a low-cost maintenance and has a high reliability. However,tapered channel (TAPCHAN) systems are not suitable for installa-tion on all types of shores [6].

3.1.3. Pendular deviceThese systems consist of a box rectangular in shape which is

open to the sea at one end. A flap is hinged over this opening. Asthe wind hit the flap, it moves back and forth. This motion is usedto power a hydraulic pump and a generator [6].

3.2. Nearshore converters

These converters are realized at water depths of 10–25 m andvarying designs of oscillating water column (OWC) are applied inthese systems.

3.2.1. OspreyThe power of OSPREY developed by Wavegen was upgraded to

2 MW with the incorporation of a 1.5 MW turbine into the system.Much work has been conducted on potential commercial uses ofthis system and work is underway aimed at reducing the installa-tion costs in particular [6].

3.2.2. WOSP 3500 (Wind and Ocean Swinging Power)WOSP (Wind and Ocean Swinging Power) is an abbreviation for

combined nearshore wave and wind energy plants. An added windgenerating capacity of 1.5 MW increases the capacity of the plantto 3.5 MW [15].

3.3. Offshore converters

These converters involve using devices offshore at water depthsmore than 40 m. These types of systems require long electriccables. Major offshore converter systems include the McCabe WavePump, the OPT Wave Energy Converter (WEC), Pelamis and theArchimedes Wave Swing Mechanism [6,16].

4. General characteristics of the study area

4.1. Location, climatic and geographical characteristics

Black Sea is located in the Northern hemisphere at between 41�and 46� North latitudes and 28� and 41.5� east longitudes. Itextends over 1200 km from east to west and about 600 km in thenorth–south direction [17]. Eregli is located at the far western tipof Zonguldak Province and the south-west part of the Black Seaat 41�510 North latitudes and 31�250 east longitudes. The townshipborders the Black Sea to the north and west, the province of Zon-guldak to the east, and the townships of Akcakoca and Yigilca ofBolu Province and the township of Alapli of Zonguldak Provinceto the south (Fig. 2).

Eregli is the largest township of Zonguldak Province with anarea of 782 km2 (73.008 hectares). Eregli is predominantly charac-terized by a natural landscape with steep cliffs extending to theBlack Sea. Hills with a height ranging from 200 m to 250 m aremajor landmarks in the town. Moreover, the hill ranges extendingbetween Eregli and Alapli are an important feature of the town. Ithas a mostly mountainous and rough terrain. The terrain, which isinterrupted by valleys in some places, is inclined upwards towardsZonguldak. Unlike the province in general, Eregli, with an inclina-tion of 0–10� %, has a landscape that is well suited for industrialurbanization [18]. With the exception of beach areas, the shoreshave a high elevation and consist of step cliffs. In fact, the townshiphas cliffs to the south which are 150 m and, in some places, as lowas 1–2 m. To the northwest, cliffs extend landward betweenKoseagzi and Degirmenagzi at an inclination of 10–20� which havea height of 100–150 m and are composed of limestone layers.These occur between ‘‘active cliffs’’. The natural landscape of Eregliassumed its present appearance when dry land was reclaimedfrom the sea to build Erdemir highway and a railway line. Sincethe construction of the coast road stretching from the foot of Goz-tepe Hill to Cape Baba, the steep shore and houses which werebuilt on it and once overlooked the sea (waterfront residences)have been in their present position, in which they are up to 50–60 m inland, for more than 30 years [18].

Fig. 2. Site location map of the study area.

H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747 741

Eregli has a warm climate peculiar to the Black Sea region. Sum-mers are not very hot and dry. Average temperature does notexceed 35 �C and nor does it fall below 10 �C. The differencebetween summer and winter temperatures is around 15 �C. Thetemperature difference between day and night is 5 �C on average.The region experiences an annual humidity level of around 75%.Eregli is located in a region that receives abundant precipitation.It receives an average total annual precipitation of 1163 kg/km2.The total number of days with precipitation is 157. The townshiphas an average annual temperature of 13.7 �C. The area experi-ences 22 days of frost. The months when frost is experienced areJanuary and February. The average annual temperature in thesecoldest months of the year is 6 �C. Eregli, which does not receivecontinuous snowfall, has on average 6.5 snowy days per year.The township is dominated by northern winds in January, Februaryand March. The average wind speed the region experiences is8.8 m/s. In April and May, the weather is very still. These are themonths with the least wind. The township only receives a lightbreeze called southeasterly wind blowing at night from the landout towards the sea. June, July and August are the hottest and dri-est moths of the year, with July having an average temperature of21 �C. In September, the region experiences various winds such asnorthwesterly, northeasterly and southwesterly winds. In Octoberand November, the township is dominated by northwesterly andsouthwesterly winds and receives heavy rainfall. The rainfallcomes to an end in March [18]. Winter months have strongerwinds and in summer months wind speed is at its lowest. Charac-teristics of solar irradiance and wind conditions at a potential areashould be investigated for efficiently utilize renewable energyusing wind power and solar energy because climatic conditions,including variations in wind speed, always change [19,20]. Based

on the data on how often the wind blows from different directions,a wind rose diagram was drawn that shows wind directions pre-dominant in the study area (Table 2, Fig. 3). The directions fromwhich the winds blows at the highest speed in the study area areESE, SE and SSE and those of winds having the second-highestspeed are NNW, NW and WNW. The most prevalent wind directionin Eregli is the south east. The secondary wind direction is thenorthwest. This is the northwesterly wind which blows inlandfrom the sea and causes temperatures to drop. In other words,the study area is primarily under the influence of the force of windsblowing from the Central Anatolia Region and secondarily underthe influence of that blowing from The Black Sea.

The wind wave conditions in the western Black Sea shelf arehindcasted by Valchev et al. [22]. With the displacement of Medi-terranean cyclones to the north-east the densification of south-eastwind is monitored over the whole Black Sea basin [22].

4.2. Geological characteristics

The study area comprises, in order of age from the oldest to theyoungest, Tasmaca, Basköy, Dinlence, Liman, Kale, Sarikorkmazand Alapli formations, and alluvium (Fig. 4).

The Tasmaca formation (Crt) is blue and grey in color, and iscomposed of marl, claystone, rare siltstone and sandstone. TheBasköy formation (Crb), which is white, cream and red in color,is made up of marl-clayey limestone and a tuffite sequence witha thin layer overlying Tasmaca formation. Over the Basköy forma-tion laid the grey and ash colored Dinlence formation (Crd), whichis composed of a thick layer of a massive agglomerate-tuff interca-lation. Lying over the Dinlence formation is the Liman formation(Crl) yellow, green and crimson in color, which comprises tuff,

Table 2Average number of blowing data covering a long period of time (35 years) [21].

Directions January February March April May June July August September October November December Total

NNE 97 89 122 96 87 75 133 113 111 141 89 100 1253NE 97 80 96 46 58 77 74 82 80 111 84 72 957ENE 66 62 66 51 78 85 84 77 73 68 62 62 834E 98 101 149 120 134 184 197 166 139 137 123 140 1688ESE 343 299 343 316 387 417 469 603 622 603 525 402 5334SE 533 416 396 375 355 359 419 594 670 641 503 505 5766SSE 472 362 274 288 229 228 209 221 277 347 432 517 3856S 336 277 229 175 134 146 115 146 170 203 298 363 2592SSW 149 146 108 103 38 83 69 69 67 88 119 159 1248SW 133 97 109 91 71 80 66 53 41 69 95 121 1026WSW 143 191 263 245 202 152 132 88 73 98 136 162 1885W 210 224 220 292 270 211 137 135 90 128 179 172 2268WNW 237 231 296 320 334 288 261 211 204 232 206 240 3040NW 268 255 330 353 448 392 353 288 289 244 229 210 3659NNW 179 224 294 284 359 332 378 337 266 245 195 165 3258N 188 195 216 155 164 202 303 291 282 243 184 136 2559

Fig. 3. Wind directions prevalent in the study area.

Fig. 4. Stratigraphic columnar section of the study area [23].

742 H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747

agglomerate, rare sandstone and siltstone forming a thin layer. Theformation which overlies this formation is the crimson, grey andyellow Kale formation (Crkl), which is made up of a thin-mediumlayer of intercalated marl, claystone and tuff. The Sarikorkmaz for-mation (Crsa), which comprises an intercalation of sandstone andclaystone, and rare khaki tuff gravels lies over the Liman formation,which is discordantly overlapped by the grey and yellow Alapliformation with a thin-medium layer, composed of marl, clayey

limestone, limestone and sandstone. Alluvium (Qal), which is theyoungest unit occur in the study area and comprises uncementedsand, silt and gravel, occurs over large areas of river beds and plainbases [23].

The seismicity and tectonic structure of Turkey and adjacentareas are explained by reference to the relative movements ofthe Africa, Arabia, Eurasia and Anatolia [24]. The fact that theregion where Turkey is located contains small plates between largeplates indicates that much of Turkey lies within the earthquakezone. Anatolia has such active tectonic lines as the Alpine Fold Sys-tem and its continuation The North Anatolian Faultline (NAF), TheAegean Graben System, The East Anatolian Faultline (EAF) and TheBitlis Overthrust. The North Anatolian Faultline is a bow-shapedright lateral strike-slip fault system 1200 km in length. It extendsfrom Karliova to the east of Greece and forms the boundarybetween the Eurasia and Anatolia plates. Anatolia is pushed tothe west along the right lateral shear zone formed by this faultzone [24]. Earthquakes of various magnitudes have occurredaround the study area located in a second-degree earthquake zoneaccording the Seismic Zoning Map of Turkey. The earthquakes thatcaused severe damage are as follows; the Adapazari–HendekEarthquake which occurred on June 20, 1943 (Ms = 6.4), theBolu–Gerede Earthquake on February 1, 1944 (Ms = 7.2) theBolu–Abant Earthquake on May 26, 1957 (Ms = 7.1), the AdapazariEarthquake on July 22, 1967 (Ms = 7.2) the Izmit Gulf Earthquakeon August 17, 1999 (Ms = 7.8) and the Düzce Earthquake onNovember 12, 1999 (Ms = 7.2) [25].

4.3. The consumption of coal

Due to unfavorable effects of coal on the environment, naturalgas and nuclear energy will inevitably gain in importance in thenear future, but rising oil prices will affect natural gas prices aswell. As country is considered to be a developing country and isnot self-sufficient with regard to energy, the energy problem isour primary concern. Efficient measures must be taken to copewith ever-increasing energy deficit. It is obvious that Turkey stillneeds to import energy although energy production has beenincreased by developing new production methods and concentrat-ing on R–D (research and development) activities aimed atutilizing new and renewable resources [26]. Therefore, seriousconsideration should be given to wave energy, which is a renew-able energy sources. Although 1350 households consume naturalgas in the township, the total annual coal consumption in Eregliaccounts for about 29% of overall coal consumption in Zonguldak.

Table 3Report on monitoring sea pollution in Eregli [27].

Sampling point Date of sampling Total coliform Faecal coliform Faecal streptococcus

Kdz. Eregli 10 km beach 18.06.2008 5 3 184023.07.2008 60 10 200013.08.2008 300 34 10

Erdemir beach 18.06.2008 9 0 300023.07.2008 110 20 013.08.2008 100 0 8

Municipal beach 18.06.2008 40 0 023.07.2008 700 160 140013.08.2008 10 0 30

Mervealti beach 18.06.2008 0 0 023.07.2008 900 60 62013.08.2008 40 28 320

Table 4SO2 emissions released by The Eregli Iron and Steel Plants [27].

Units Emission(mg/m3)

Permissible limits(mg/m3)

Coking plant stack no 1 0 60Coking plant stack no 2 0Thermal power station no 1 240 1108Thermal power station no 2 72 818Thermal power station no 3 228 1048Thermal power station no 4 1649 592Thermal power station no 5 0 60Lime plant no 1 0 –Lime plant no 2 0 –Lime plant no 3 0 –Lime plant no 4 0 –Sinter 0 –Slab furnace no 1 88 –Slab furnace no 2 214 –Blast furnace no 1 0 –Blast furnace no 2 0 –

Table 5CO emissions released by The Eregli Iron and Steel Plants [27].

Units Emission(mg/m3)

Permissible limits(mg/m3)

Coking plant stack no 1 3301 100Coking plant stack no 2 1583Thermal power station no 1 21 145Thermal power station no 2 52 131Thermal power station no 3 13 142Thermal power station no 4 24 124Thermal power station no 5 4 100Lime plant no 1 21145Lime plant no 2 18,160Lime plant no 3 15Sinter 46,304 –Slab furnace no 1 53.3Slab furnace no 2 79Blast furnace no 1 1207Blast furnace no 2 23

H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747 743

4.4. Pollution

It is acknowledged today that, with burning of fossil fuels andparticularly progressive destruction of forests, CO2 along withother gases in the air create the greenhouse effect and trap thesun’s radiations at a close distance from the earth surface, whichin turn causes the earth to get warm and alters the climate. Sulfurdioxide (SO2) and nitrogen oxide (NOx) released into the atmo-sphere combine with water vapor to change into sulfate andnitrate. Similarly, nitrogen monoxide (NO) emitted into the atmo-sphere by car exhausts is converted into nitrogen dioxide (NO2).Nitrogen dioxide in turn (NO2) is oxidized to nitrate acid (HNO3)by hydroxyl radicals. As a result, rain absorbs acids at high alti-tudes and descends to the ground. Thus, as the soil is acidized,most of the toxic metals become dissolved and mix with under-ground water. As we can provide more examples of similar phe-nomena to summarize the situation, the atmosphere is not asystem in which we can dump our wastes indefinitely [26]. Table 3gives the results of analyses conducted by the Zonguldak RegionalHealth Authority on sea water samples taken from Eregli [27].

As The Iron and Steel Plants in Eregli use novel technology, theycause little air pollution [27] (Tables 4–7). In view of the facts thatsea, air and soil pollution is a challenge that must be handled inorder to create a healthy life and environment and even a negligi-ble amount of pollution will have an unfavourable effect on ourquality of life, it is clear that it will pose a serious problem unlessdrastic measures are taken to deal with it. Although renewableenergy sources are natural, mechanical and thermal, repeat

themselves as long as life continues, it is possible to produce asmuch energy as envisaged, and they harm the environment to alesser extent than fossil fuels, they will not probably achieve indus-trial efficiency as fast as fossil fuels did [1]. Therefore, althoughheavy industry in Eregli continues to use fossil fuels, it is importantthat at least the energy demand of households be satisfied withrenewable energy, particularly wave energy in order to have aclean and healthy environment and produce cheap energy inEregli, where a considerable amount of coal is mined.

4.5. Studies performed in the study area and its vicinity

Uygur et al. [9] studied the energy capacity of sea waves createdby the effects of storms and winds that are frequently experiencedin the western Black Sea region, carried out practical and theoret-ical investigation into the subject and emphasized that it is impor-tant that the wave energy potential presented by the Akcakocashoreline be identified because the region is home to many sectors,mainly tourism, agriculture and animal husbandry and has transitconnections to major cities. They studied observational datarecorded between 07.00, 14.00 and 21.00 h in previous years(1996–2000) at Akcakoca Meteorological Observatory of the Gen-eral Directorate affiliated with the Turkish Meteorological Service.As a result of studies conducted, total annual wave height of theAkcakoca shores over 5 years was calculated to be 0.55 m [9](Table 8).

In order to calculate the real wave energy potential, it isnecessary to measure wave speed as well. Therefore, the energy

Table 6NOx emissions released by The Eregli Iron and Steel Plants [27].

Units Emission(mg/m3)

Permissiblelimits (mg/m3)

Coking plant stack no 1 602 500Coking plant stack no 2 –Thermal power station no 1 456 800Thermal power station no 2 606 800Thermal power station no 3 360 800Thermal power station no 4 382 597Thermal power station no 5 63 500Lime plant no 1 81Lime plant no 2 100Lime plant no 3 83Sinter 1432 –Slab furnace no 1 756Slab furnace no 2 214Blast furnace no 1 70Blast furnace no 2 59

Table 7Particulate emissions (PM) released by The Eregli Iron and Steel Plants [27].

Units Emission(mg/m3)

Permissiblelimits (mg/m3)

Coking plant stack no 1 8 250Thermal power station no 5 12 200Lime plant no 1 1510Lime plant no 2 517Lime plant no 3 10Sinter 300 –Slab furnace no 1 2Slab furnace no 2 2.4Blast furnace no 1 2

Table 8Observational wave data obtained from The Akcakoca Observatory [9].

Years Max. waveheight (m)

Average waveheight (m)

Number of waves with a heightof more than 3 m

1996 6 0.48 41997 9 0.54 171998 6 0.55 101999 10 0.62 202000 7 0.49 8

Average 7.60 0.54 11.80

Table 9Main renewable energy sources and their usage forms [1].

Energy source Energy conversion and usage options

Hydropower Power generationModern

biomassHeat and power generation, pyrolysis, gasification,digestion

Geothermal Urban heating, power generation, hydrothermal, hot dryrock

Solar Solar home system, solar dryers, solar cookersDirect solar Photovoltaics, thermal power generation, water heatersWind Power generation, wind generators, windmills, water

pumpsWave Numerous designsTidal Barrage, tidal stream

744 H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747

potential was calculated parametrically and the wave powerpotential of the shores in Akcakoca was found to be (P): P = 690–2802 Cg (W/m). If wave group velocity (Cg) is assumed to be10 m/s (36 km/h), wave power potential of the shores in Akcakocais found to be the lowest 6 kW/m and the highest 28 kW/m.Although these semi-empirical results help produce some sugges-tions, wave velocity, average wave height and period must be mea-sured by means of electronic devices in order to make moreaccurate judgments [9]. Considering the existing systems used toconvert wave energy into mechanical and electrical energy, andinvestment costs involved, it can be said that the power potentialcalculated is sufficient, but not cost-efficient [28]. As systems thatproduce electrical energy from sea waves are developed for oceanshores with a very high wave height, suitable technologies must bedeveloped for the seas surrounding Turkey [9].

Akpinar and Komurcu [17] studied the quantity of wave energyresource in deep and shallow waters in the Black Sea and map theavailable energy and its monthly and seasonal variations. Theyestimated wave parameters for 15 years (1995–2009) and calcu-lated the annual, seasonal, and monthly mean wave energy. Thesouth-western part of the Black Sea is affected from the waves

more than the eastern part, and identified to possess higher waveenergy and power compared to the eastern part of the Black Seaand mean annual wave energy resource in the Black Sea is up to3 kW/m. Levels of significant wave height and wave power in thewestern part of the Black Sea are up to 160% and 250% larger thanthose in the eastern part of the Black Sea, respectively [17].

The seasonal distribution of storm events in the Black Sea wasassessed by Arkhipkin et al. [29]. They observed wave heightsexceeding 5 m in February and wave heights exceeding 4 m in July.Arkhipkin et al. [29] calculated average significant wave height is0.5–0.55 m, maximal significant wave height is 5–5.5 m, maximalwave length is 55 m, maximal wave period is 7 s and wave heightof 100 year repeatability is 5–6 m at the south-west part of theBlack Sea including close area of Eregli [29].

The Black Sea shoreline is the most efficient region in Turkey asregards the formation of waves in its seas and their features. Thoseregions of Turkey should be identified which have renewableenergy potential and where energy generated can be readily dis-tributed, and the potential energy values of these regions shouldbe calculated and investments should be made in suitable regions.Studies conducted in this framework have investigated the energycapacity of sea waves created by storms and winds that frequentlyoccur in the western Black Sea region and theoretical and practicalwork has been carried out on the subject [30]. A TÜB_ITAK-sponsored project (Turkish abbreviation for the Turkish scientificand technical researches institution) in 2004 involving a modelstudy initiated in Eregli had to be abandoned due to the lack offunds [31]. It is evident from Table 9 that main renewable energysources are used for various purposes; wave energy is still under-going the processes of draft, trial, application and development [1].

5. Shoreline converters and geological structure

An examination of wave energy systems that can be installed inEregli in parallel to ever-developing technology reveals that, due tothe necessity of a temperature difference of 20 �C between the sur-face and water at a depth of 1000 m and pipes 300–400 m in lengthand 2.5 in diameter, closed cycle systems have not been foundeconomic. Open cycle systems, despite their low efficiency, arepreferred because they are advantageous in that they can be usedfor producing fresh water and practicing sea food husbandry. Sincenearshore and offshore converters have to be installed in geo-graphically distant locations and accordingly require additionalcosts (sea bed cables etc.) and investments to efficiently transmitthe energy produced by systems floating in the middle of the sea,Eregli is more suitable for wave energy production through shore-line converters rather than other converters, at least in the begin-ning [32]. In shoreline converters, energy production systems areinstalled on the shore or buried. They are easier to built and main-tain compared to other converters. In addition, they do not require

Fig. 5. The oscillating water column system (OWC) [33].

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deep water connections or underwater electrical cables. However,due to the wave regime characterized by less power, they tend toproduce less wave energy. Moreover, these types of converterscannot become widespread due to limitations such as shorelinegeology, tides and the concern for shoreline preservation. ‘‘oscillat-ing water column system (OWC) consists of a partially submerged,hollow structure, which is open to the sea below the water line(Fig. 5). This structure encloses a column of air on top of a columnof water. As waves impinge upon the device, they cause the watercolumn to rise and fall, which alternatively compresses anddepressurises the air column. If this trapped air is allowed to flowto and from the atmosphere via a turbine, energy can be extractedfrom the system and used to generate electricity. Energy is usuallyextracted from the reversing air flow by Wells’ turbines, which

Fig. 6. The tapered channel s

Fig. 7. The geological structure of the study area [23] and a map s

have the property of rotating in the same direction regardless ofthe direction to the airflow’’ [33]. As the oscillating water columnsystems (OWC), a shoreline converter, a partially submerged struc-tures below sea level that are made of steel or concrete andextends into the sea, they can be installed on and in alluvium madeup of uncemented sand, clay, silt and conglomerate of Quaternaryage which stretch along the west of Eregli, beach areas composedof seaside sand and slope wash consisting of clastic rock fragmentsoccurring in valley bases. Before an oscillating water column sys-tem (OWC) is installed in beach areas that offer flat land close tothe sea, plans should be made which put into consideration popu-lation density, tourism movement and landscape designing as wellas social life. The flat land which comprises the plains around theshores of Kepez Stream and Guluc River to south of Goztepe andthe 2.5 km Uzunkum beach on the shores of these plains, and theflat area between Eregli Iron and Steel Plant and the shorelineare suitable for oscillating water column (OWC) converters thatwould not put much burden on the tourism movement, social lifeand landscape in Eregli.

The tapered channel system (TAPCHAN) (Fig. 6), a shorelineconverter is an adaptation of the conventional hydroelectric energyproduction system. These systems have wall height of 3–5 m abovesea level and consist of a tapering channel which feeds into a res-ervoir constructed on the edge of a cliff. ‘‘Waves enter the wide endof the channel and, as they propagate down the narrowing channel,the wave height is amplified until the wave crests spill over the

ystem (TAPCHAN) [33].

howing possible locations suitable for wave energy converter.

746 H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747

walls to the reservoir, which is raised above sea level. The water inthe reservoir returns to the sea via a conventional low head tur-bine, which generates a stable output due to the storage effectsof the reservoir’’ [33]. With the exception of beach areas, the shoreshave a high elevation and consist of step cliffs in Eregli. In fact, thetownship has cliffs to the north which are 150 m and, in someplaces, as low as 1–2 m. To the northeast, between Koseagzi andDegirmenagzi cliffs extend landward at an inclination of 10–12�which have a height of 100–150 m and are composed of limestonelayers. These areas which comprise Baskoy formation composed ofa thin layer of a marl and clayey limestone intercalation with tuf-fite and sandstone, the Dinlence formation lying over this forma-tion to the south west of these areas and to the north west ofEregli, which is composed of a thick layer of a massive agglomer-ate–tuff intercalation, the Liman formation lying to the northwestof Eregli, which is made up of tuff, agglomerate, rare sandstone andsiltstone, and the Alapli formation lying to the southwest of Eregli,which is composed of marl, clayey limestone, limestone and sand-stone, are all suitable areas for the installation of tapering channelsystems (TAPCHAN) that have a wall height above sea level (Fig. 7).

Yan [34] indicated the expedited transition towards a lower-carbon energy system presented opportunities to ensure energysecurity, rebuild national and regional economies, and addressclimate change and local pollution [34]. Li and Willman [35] pre-sented results of introducing tidal power in Southern Alaska. Theystated that it is necessary to distribution and transmission analysisin the future [35]. However it seems unlikely that sea based energydevices will be able to satisfy the electricity needs of the wholeworld, it can form one of a suite of measures necessary to find asustainable solving to future energy demands [36]. However waveenergy is a new, rapidly expanding field promising to generate sig-nificant amounts of electricity in coastal areas [37]. Owing to thedeterioration of the worldwide environment, the increasing scar-city and high cost of the conventional energy sources (fossil fuels),renewable energy is currently one of the main areas of researchand investment [38].

Wave measurements in Akcakoca located very close to Eregli [9]and the studies in whole Black Sea basin [17] show that Eregli ismore suitable for establish a wave measurement station to waveenergy converters. For a analyses and applications of wave con-verters in Eregli and to help relevant decision makers it is neces-sary to measure wave velocity, wave period, wave height,distance between two waves like a other applications about waveconverters. This study has been completed without financial sup-port. Instrumented measurement system is required instead ofobservational meteorological and geological measurements. Finan-cial support, specialist team and equipment are required for pro-cess measurement and observation. So this study might be usedas a basis for the next researches.

6. Conclusions

Energy sources can be broken into three categories: fossil fuels,renewable sources and nuclear sources. Renewable energy sources(RES) are also referred to as alternative resources. Renewableenergy sources satisfy 14% of the world-wide energy demand.Although wave energy, a renewable energy source, is clean, inex-pensive and eco friendly, cannot be a primary energy source andcannot be stored primarily. Main renewable energy sources areused for various purposes, whereas wave energy is still undergoingthe processes of design, trial, application and development.

The most efficient region as regards wave formations in the seasof Turkey and features that these waves have is The Black Seashoreline. Although Eregli consumes 17,740,906 m3 of natural gasand 350,000,000 kW h of electricity per year, the amount of coal

consumed accounts for 29% of the total consumption in Zonguldak.As Eregli Iron and Steel Plants employ novel technology, they causelittle air pollution. The heavy industry in Eregli still uses fossilfuels. However, it is important that the energy need of householdsalone be met with renewable energy source, particularly waveenergy, for this would not only help achieve a clean and healthyenvironment, but also produce clean and inexpensive energy wave.Considering energy systems that can be installed in Eregli in paral-lel to ever-developing technology, it is obvious that, due to thenecessity of a temperature difference of 20 �C between the surfaceand water at a depth of 1000 m and pipes 300–400 m of length and2.5 of diameter, closed cycle systems have not been established notto be ergonomic. Despite their low efficiency, open cycle systemsare preferred to closed ones because they provide the advantageof being used for producing fresh water and practicing sea foodhusbandry.

Wave energy has shoreline, nearshore and offshore converters.Since near shore and offshore converters have to be installed ingeographically distant locations and thus require additional costs(sea bed cables etc.) and investments to efficiently transmit theenergy to grid systems that is produced by systems floating inthe middle of the sea, shoreline converters in Eregli, at least inthe beginning, are more suitable for wave energy production com-pared to other converters.

The study area comprises, in order of age from the oldest to theyoungest, the Tasmaca formation (Crt), which is composed of marl,claystone, rare siltstone and sandstone. The Basköy formation(Crb), which is made up of marl, clayey limestone and a tuffitesequence with a thin layer, the Dinlence formation (Crd), whichis made up of a massive agglomerate–tuff intercalation, the Limanformation, which comprises tuff, agglomerate, rare sandstone andsiltstone forming a thick layer, Kale formation (Crkl), which ismade up of a thin-medium layer of intercalated marl, claystoneand tuff, the Sarikorkmaz formation (Crsa), which comprises anintercalation of sandstone and claystone, and rare khaki tuff grav-els, the Alapli formation with a thin-medium layer, composed ofmarl, clayey limestone, limestone and sandstone, slope wash com-posed of clastic rock fragments, and alluvium comprising unce-mented sand, silt and gravel and occurring over large areas ofriver beds and plain bases.

As the oscillating water column systems (OWC), a shorelineconverter, are a partially submerged structures below sea level thatare made of steel or concrete and extend into the sea, they can beinstalled on and in alluvium made up of uncemented sand, clay, siltand conglomerate of Quaternary age which stretch along the westof Eregli, beach areas composed of seaside sand and slope washconsisting of clastic rock fragments occurring in valley bases. TheUzunkum beach and the flat area between Eregli Iron and SteelPlants (Erdemir) built in plains and the shoreline are suitable foroscillating water column converters, for they would not put astraint on the tourism movement, social life and landscape in Ere-gli. The Basköy formation lying to the northeast of Eregli, whichconsists of a thin layer of a marl-clayey limestone intercalationwith tuffite and sandstone, the Dinlence formation to the north-west, composed of a massive intercalation of agglomerate and tuff,the Liman formation, made up of tuff, agglomerate, rare sandstoneand siltstone, and the Alapli formation to the southwest which ismade up of marl, clayey limestone, limestone and sandstone areall regions that are suitable for the installation of tapered channelsystem (TAPCHAN) with a wall height above sea level.

Since systems for electrical energy production from sea waveshave been developed for ocean shores with very high wave height,technologies must be developed that can be applied on the shoresof the seas surrounding Turkey. Those regions in Turkey must beidentified that represent renewable energy potential and wherethe energy produced can be readily transmitted to main power

H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747 747

grids, and the potential energy that these regions have must be cal-culated and investments should be made in suitable in suitableregions in the soonest possible time.

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