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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 Eregli
on the western Black Sea coast of Turkey
H. Keskin Citiroglu a,⇑, A. Okur b,1
a
b
YIKOB, Investment Monitoring and Coordination Presidency, Aydin, Turkey
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 2013
Received in revised form 16 May 2014
Accepted 22 May 2014
Available online 12 June 2014
Keywords:
Wave energy
Renewable energy
Shoreline converter
Geology
Eregli
Black Sea
a b s t r a c t
Major renewable energy types that are natural and sustainable and do not harm the environment include
water, wind, solar, geothermal, hydrogen, oceanic, biofuel (organic fuel), wave and tidal energies. Of
these, wave energy is a type of inexpensive and clean energy that does not require capital input and
any costs except for those of initial investment and maintenance, does not release any pollutants into
the atmosphere and thus presents a huge potential. The total amount of coal consumed in Eregli on
the 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 needs
of even households in Eregli through renewable energy sources, mainly wave energy is of utmost importance 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 the
beginning, for shoreline converters in Eregli. Eregli has suitable areas for the installation of an oscillating
water column and tapered channel systems in terms of its geological features.
Ó 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 sources
can also be referred to as alternative resources. Renewable energy
sources meet 14% of the world-wide demand [1]. As is clear from
its name, renewable energy refers to a type of energy that repeats
itself, that is to say, is renewed and will never become exhausted as
long as the world exists. Among those sources that can be cited are
water, wind, solar, geothermal, hydrogen, oceanic, biofuel (organic
fuel), wind and tidal energies. As these energy types continuously
⇑ Corresponding author. Tel.: +90 (256) 212 24 16; fax: +90 (256) 214 36 53.
E-mail addresses: [email protected] (H. Keskin Citiroglu), asliokur1983@
hotmail.com (A. Okur).
1
Tel.: +90 (543) 651 74 11; fax: +90 (372) 378 16 42.
http://dx.doi.org/10.1016/j.apenergy.2014.05.053
0306-2619/Ó 2014 Elsevier Ltd. All rights reserved.
renew themselves, they never face the danger of being depleted
and nor do they cause harm to the environment. In addition,
renewable energy sources can be used directly or converted into
another form of energy [2,3]. Also, renewable energy includes biomass, wind and solar energy applications [4]. Solar radiations are
one of the basic energy sources of the world. 70% of the sun’s radiations falling on the earth are held by the seas. Therefore, the seas
and oceans can be a good source of energy if suitable methods are
employed to harness the energy stored in them. Waves formed
through the friction between a wind and the sea surface results
in the wind’s energy being transported to water. As water is heavier than air, the energy formed by the waves is 800–1000 times
greater 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 transformation got under way following the sharp increase in oil prices
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H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747
Fig. 1. Wave power potential that the seas and oceans of the world present (kW/m) [8,9].
Table 1
Annual 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)
Heat (MTEP)
977,000
80,000
6105
500
305
25
Electric energy (GW h)
430
215
124.5
Electric energy (GW h)
Electric energy (GW h)
Electric energy (GW h)
400
–
150
110
180
18
50
–
–
Geothermal energy
Electric energy (GW h)
Heat (MTEP)
–
31,500
–
7500
1.4
2843
Biomass energy
Fuel (conventional MTEP)
Fuel (modern MTEP)
30
90
10
40
7
25
Hydraulic energy
Wind energy
Terrestrial wind energy
Marine wind energy
Sea wave energy
in 1973. Certain European countries considered exploitable wave
energy sources to be a potential power supply and put forward
support measures and relevant programmes. Since many state
and privately funded research programmes were initiated, some
European countries such as Norway, Sweden, Denmark and particularly England, Portugal and Ireland have aimed to develop wave
energy conversion technologies that can be operated industrially
in the medium and long run [6]. The first commercial wave power
plant Limpet 500 was built on the isle of Islay in Scotland in 2000
and it has supplied electricity to the UK power distribution grid
since November 2000. Limpet 500 power plant with a capacity of
0.5 MW was designed by Wavegen using an oscillatory water column to be installed on abandoned shores [7]. More than 1000 wave
energy conversion patents have been granted in Japan, North
America and Europe [6]. Fig. 1 gives the potential of wave power
stored in the seas and oceans of the world.
The coastline of Turkey is approximately 8210 km with the
exception of that of the Marmara region. A mere 1/5 of this can
be used for electricity production due to fishing, tourism and other
coastal activities [10]. The wave energy potential is presented by
this 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 Turkish
coast can be utilized to meet the electricity demand [11]. The most
efficient region in terms of wave formations in the seas of Turkey
and the qualities these waves have is the Black Sea coastline. Those
regions in Turkey should be identified which present the potential
for renewable energy and where this energy can be readily put into
use, and the values of potential energy occurring in these regions
should be calculated and investments should be made in suitable
regions in the soonest possible time [9].
A review of the energy profile of Turkey makes the role and
importance of renewable energy sources clearly seen (Table 1).
However, renewable energy sources are used to quite a small
extent. It is observed that energy sources of fossil origin accounts
for nearly half of the primary energy production. Coal accounts
for 47% of electric energy production in Turkey, oil and natural
gas 15%, hydraulic and geothermal sources 13%, non-commercial
fuels 23% and the other renewable fuels about 2% [13].
As the coasts of Turkey are densely populated, wave power
plants would locate in the same place as that of energy consumption. This would provide huge gains in energy transmission costs.
Wave energy plants would be connected to the national power grid
and, at times when energy production is at the highest level, the
existing hydroelectric power plants would be disconnected and
be held in reserve. Since electric energy that would be produced
by wave power plants, it would be preferred over other fuels,
forests would be preserved and expand, thus improving air
quality [14].
2. Systems employed in wave energy production
The method used in the production of wave energy is as follows; storing the force created by the Archimedes’ principle and
gravity as a potential energy and balancing the energy imparted
by waves with the stored energy and thus obtaining linear energy
followed by converting this energy into electrical energy by using
present technologies.
2.1. Closed cycle systems
In closed cycle systems, when a special fluid meets with hot
water, it vaporizes and drives the steam turbine. After that, the
steam meets the cold water at the bottom and condenses again.
This process repeats itself in a cyclic manner. In order for this system to operate well, there must be a temperature difference of
20 °C between the surface and water at a depth of 1000 m. Moreover, the water in the cycle pipes must have a flow rate of 48 m3.
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H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747
Another challenge is the necessity to use pipes 300–400 m in
length and 2.5 m in diameter [14].
2.2. Open cycle systems
Open cycle systems use water in place of a special fluid. As sea
water has a high boiling point, the external pressure is reduced sufficiently to achieve boiling at low temperatures. Similarly, the
pressure is changed to realize the condensation process as well.
The amount of water that is vaporized for these changes of state
to occur is 1500 m3 per 1 MW. This means fresh water yield. This
feature 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 determine
the amount of wave energy to be produced. Therefore, there has
been a sharp increase in studies conducted to produce wave
energy.
3.1. Shoreline converters
In these applications, energy producing installations are
mounted on or buried under shores. They are easier to build and
maintain compared to other converters. In addition, they do not
require deep water connections and long underwater cables. On
the other hand, due to the wave regime with less power, relatively
a small amount of wave energy can be produced. These converters
are prevented from becoming widespread by such factors as shoreline 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 system
incorporates a water column and an air column above it. When the
system is hit by waves, the water column rises and lowers, which
in turn causes the air column to become pressurized or the pressure in it to be relieved depending on the position of water column.
The compressed air is transferred to the turbine which drives the
electric generator. Thus, the system produces energy and the
energy 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 feeds
into a reservoir constructed on the edge of a cliff. The narrowing of
the channel causes the wave height to increase and the rising
waves spill over the walls of the channel into the reservoir. As
the water is stored in the reservoir, the kinetic energy of the moving waves is converted into potential energy. The stored water is
fed through a turbine. Since the system has few moving parts, it
has a low-cost maintenance and has a high reliability. However,
tapered channel (TAPCHAN) systems are not suitable for installation on all types of shores [6].
3.1.3. Pendular device
These systems consist of a box rectangular in shape which is
open to the sea at one end. A flap is hinged over this opening. As
the wind hit the flap, it moves back and forth. This motion is used
to power a hydraulic pump and a generator [6].
3.2. Nearshore converters
These converters are realized at water depths of 10–25 m and
varying designs of oscillating water column (OWC) are applied in
these systems.
3.2.1. Osprey
The 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 of
this system and work is underway aimed at reducing the installation 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 wind
generating capacity of 1.5 MW increases the capacity of the plant
to 3.5 MW [15].
3.3. Offshore converters
These converters involve using devices offshore at water depths
more than 40 m. These types of systems require long electric
cables. Major offshore converter systems include the McCabe Wave
Pump, the OPT Wave Energy Converter (WEC), Pelamis and the
Archimedes 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. It
extends over 1200 km from east to west and about 600 km in the
north–south direction [17]. Eregli is located at the far western tip
of Zonguldak Province and the south-west part of the Black Sea
at 41°510 North latitudes and 31°250 east longitudes. The township
borders the Black Sea to the north and west, the province of Zonguldak to the east, and the townships of Akcakoca and Yigilca of
Bolu Province and the township of Alapli of Zonguldak Province
to the south (Fig. 2).
Eregli is the largest township of Zonguldak Province with an
area of 782 km2 (73.008 hectares). Eregli is predominantly characterized by a natural landscape with steep cliffs extending to the
Black Sea. Hills with a height ranging from 200 m to 250 m are
major landmarks in the town. Moreover, the hill ranges extending
between Eregli and Alapli are an important feature of the town. It
has a mostly mountainous and rough terrain. The terrain, which is
interrupted by valleys in some places, is inclined upwards towards
Zonguldak. Unlike the province in general, Eregli, with an inclination of 0–10° %, has a landscape that is well suited for industrial
urbanization [18]. With the exception of beach areas, the shores
have a high elevation and consist of step cliffs. In fact, the township
has cliffs to the south which are 150 m and, in some places, as low
as 1–2 m. To the northwest, cliffs extend landward between
Koseagzi and Degirmenagzi at an inclination of 10–20° which have
a height of 100–150 m and are composed of limestone layers.
These occur between ‘‘active cliffs’’. The natural landscape of Eregli
assumed its present appearance when dry land was reclaimed
from the sea to build Erdemir highway and a railway line. Since
the construction of the coast road stretching from the foot of Goztepe Hill to Cape Baba, the steep shore and houses which were
built 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].
H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747
741
Fig. 2. Site location map of the study area.
Eregli has a warm climate peculiar to the Black Sea region. Summers are not very hot and dry. Average temperature does not
exceed 35 °C and nor does it fall below 10 °C. The difference
between summer and winter temperatures is around 15 °C. The
temperature 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 township
has an average annual temperature of 13.7 °C. The area experiences 22 days of frost. The months when frost is experienced are
January and February. The average annual temperature in these
coldest months of the year is 6 °C. Eregli, which does not receive
continuous snowfall, has on average 6.5 snowy days per year.
The township is dominated by northern winds in January, February
and March. The average wind speed the region experiences is
8.8 m/s. In April and May, the weather is very still. These are the
months with the least wind. The township only receives a light
breeze called southeasterly wind blowing at night from the land
out towards the sea. June, July and August are the hottest and driest moths of the year, with July having an average temperature of
21 °C. In September, the region experiences various winds such as
northwesterly, northeasterly and southwesterly winds. In October
and November, the township is dominated by northwesterly and
southwesterly winds and receives heavy rainfall. The rainfall
comes to an end in March [18]. Winter months have stronger
winds and in summer months wind speed is at its lowest. Characteristics of solar irradiance and wind conditions at a potential area
should be investigated for efficiently utilize renewable energy
using 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 predominant in the study area (Table 2, Fig. 3). The directions from
which the winds blows at the highest speed in the study area are
ESE, SE and SSE and those of winds having the second-highest
speed are NNW, NW and WNW. The most prevalent wind direction
in Eregli is the south east. The secondary wind direction is the
northwest. This is the northwesterly wind which blows inland
from the sea and causes temperatures to drop. In other words,
the study area is primarily under the influence of the force of winds
blowing from the Central Anatolia Region and secondarily under
the influence of that blowing from The Black Sea.
The wind wave conditions in the western Black Sea shelf are
hindcasted by Valchev et al. [22]. With the displacement of Mediterranean cyclones to the north-east the densification of south-east
wind 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 the
youngest, Tasmaca, Basköy, Dinlence, Liman, Kale, Sarikorkmaz
and Alapli formations, and alluvium (Fig. 4).
The Tasmaca formation (Crt) is blue and grey in color, and is
composed of marl, claystone, rare siltstone and sandstone. The
Basköy formation (Crb), which is white, cream and red in color,
is made up of marl-clayey limestone and a tuffite sequence with
a thin layer overlying Tasmaca formation. Over the Basköy formation laid the grey and ash colored Dinlence formation (Crd), which
is composed of a thick layer of a massive agglomerate-tuff intercalation. Lying over the Dinlence formation is the Liman formation
(Crl) yellow, green and crimson in color, which comprises tuff,
742
H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747
Table 2
Average 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
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
N
97
97
66
98
343
533
472
336
149
133
143
210
237
268
179
188
89
80
62
101
299
416
362
277
146
97
191
224
231
255
224
195
122
96
66
149
343
396
274
229
108
109
263
220
296
330
294
216
96
46
51
120
316
375
288
175
103
91
245
292
320
353
284
155
87
58
78
134
387
355
229
134
38
71
202
270
334
448
359
164
75
77
85
184
417
359
228
146
83
80
152
211
288
392
332
202
133
74
84
197
469
419
209
115
69
66
132
137
261
353
378
303
113
82
77
166
603
594
221
146
69
53
88
135
211
288
337
291
111
80
73
139
622
670
277
170
67
41
73
90
204
289
266
282
141
111
68
137
603
641
347
203
88
69
98
128
232
244
245
243
89
84
62
123
525
503
432
298
119
95
136
179
206
229
195
184
100
72
62
140
402
505
517
363
159
121
162
172
240
210
165
136
1253
957
834
1688
5334
5766
3856
2592
1248
1026
1885
2268
3040
3659
3258
2559
Fig. 3. Wind directions prevalent in the study area.
limestone, limestone and sandstone. Alluvium (Qal), which is the
youngest unit occur in the study area and comprises uncemented
sand, silt and gravel, occurs over large areas of river beds and plain
bases [23].
The seismicity and tectonic structure of Turkey and adjacent
areas are explained by reference to the relative movements of
the Africa, Arabia, Eurasia and Anatolia [24]. The fact that the
region where Turkey is located contains small plates between large
plates indicates that much of Turkey lies within the earthquake
zone. Anatolia has such active tectonic lines as the Alpine Fold System and its continuation The North Anatolian Faultline (NAF), The
Aegean Graben System, The East Anatolian Faultline (EAF) and The
Bitlis Overthrust. The North Anatolian Faultline is a bow-shaped
right lateral strike-slip fault system 1200 km in length. It extends
from Karliova to the east of Greece and forms the boundary
between the Eurasia and Anatolia plates. Anatolia is pushed to
the west along the right lateral shear zone formed by this fault
zone [24]. Earthquakes of various magnitudes have occurred
around the study area located in a second-degree earthquake zone
according the Seismic Zoning Map of Turkey. The earthquakes that
caused severe damage are as follows; the Adapazari–Hendek
Earthquake which occurred on June 20, 1943 (Ms = 6.4), the
Bolu–Gerede Earthquake on February 1, 1944 (Ms = 7.2) the
Bolu–Abant Earthquake on May 26, 1957 (Ms = 7.1), the Adapazari
Earthquake on July 22, 1967 (Ms = 7.2) the Izmit Gulf Earthquake
on August 17, 1999 (Ms = 7.8) and the Düzce Earthquake on
November 12, 1999 (Ms = 7.2) [25].
4.3. The consumption of coal
Fig. 4. Stratigraphic columnar section of the study area [23].
agglomerate, rare sandstone and siltstone forming a thin layer. The
formation which overlies this formation is the crimson, grey and
yellow Kale formation (Crkl), which is made up of a thin-medium
layer of intercalated marl, claystone and tuff. The Sarikorkmaz formation (Crsa), which comprises an intercalation of sandstone and
claystone, and rare khaki tuff gravels lies over the Liman formation,
which is discordantly overlapped by the grey and yellow Alapli
formation with a thin-medium layer, composed of marl, clayey
Due to unfavorable effects of coal on the environment, natural
gas and nuclear energy will inevitably gain in importance in the
near future, but rising oil prices will affect natural gas prices as
well. As country is considered to be a developing country and is
not self-sufficient with regard to energy, the energy problem is
our primary concern. Efficient measures must be taken to cope
with ever-increasing energy deficit. It is obvious that Turkey still
needs to import energy although energy production has been
increased by developing new production methods and concentrating on R–D (research and development) activities aimed at
utilizing new and renewable resources [26]. Therefore, serious
consideration should be given to wave energy, which is a renewable energy sources. Although 1350 households consume natural
gas in the township, the total annual coal consumption in Eregli
accounts for about 29% of overall coal consumption in Zonguldak.
743
H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747
Table 3
Report 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
23.07.2008
13.08.2008
5
60
300
3
10
34
1840
2000
10
Erdemir beach
18.06.2008
23.07.2008
13.08.2008
9
110
100
0
20
0
3000
0
8
Municipal beach
18.06.2008
23.07.2008
13.08.2008
40
700
10
0
160
0
0
1400
30
Mervealti beach
18.06.2008
23.07.2008
13.08.2008
0
900
40
0
60
28
0
620
320
Table 4
SO2 emissions released by The Eregli Iron and Steel Plants [27].
Table 5
CO emissions released by The Eregli Iron and Steel Plants [27].
Units
Emission
(mg/m3)
Permissible limits
(mg/m3)
Units
Emission
(mg/m3)
Permissible limits
(mg/m3)
Coking plant stack no 1
Coking plant stack no 2
Thermal power station no
Thermal power station no
Thermal power station no
Thermal power station no
Thermal power station no
Lime plant no 1
Lime plant no 2
Lime plant no 3
Lime plant no 4
Sinter
Slab furnace no 1
Slab furnace no 2
Blast furnace no 1
Blast furnace no 2
0
0
240
72
228
1649
0
0
0
0
0
0
88
214
0
0
60
Coking plant stack no 1
Coking plant stack no 2
Thermal power station no
Thermal power station no
Thermal power station no
Thermal power station no
Thermal power station no
Lime plant no 1
Lime plant no 2
Lime plant no 3
Sinter
Slab furnace no 1
Slab furnace no 2
Blast furnace no 1
Blast furnace no 2
3301
1583
21
52
13
24
4
21145
18,160
15
46,304
53.3
79
1207
23
100
1
2
3
4
5
1108
818
1048
592
60
–
–
–
–
–
–
–
–
–
4.4. Pollution
It is acknowledged today that, with burning of fossil fuels and
particularly progressive destruction of forests, CO2 along with
other gases in the air create the greenhouse effect and trap the
sun’s radiations at a close distance from the earth surface, which
in turn causes the earth to get warm and alters the climate. Sulfur
dioxide (SO2) and nitrogen oxide (NOx) released into the atmosphere combine with water vapor to change into sulfate and
nitrate. Similarly, nitrogen monoxide (NO) emitted into the atmosphere 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 altitudes and descends to the ground. Thus, as the soil is acidized,
most of the toxic metals become dissolved and mix with underground water. As we can provide more examples of similar phenomena to summarize the situation, the atmosphere is not a
system in which we can dump our wastes indefinitely [26]. Table 3
gives the results of analyses conducted by the Zonguldak Regional
Health Authority on sea water samples taken from Eregli [27].
As The Iron and Steel Plants in Eregli use novel technology, they
cause little air pollution [27] (Tables 4–7). In view of the facts that
sea, air and soil pollution is a challenge that must be handled in
order to create a healthy life and environment and even a negligible amount of pollution will have an unfavourable effect on our
quality of life, it is clear that it will pose a serious problem unless
drastic measures are taken to deal with it. Although renewable
energy sources are natural, mechanical and thermal, repeat
1
2
3
4
5
145
131
142
124
100
–
themselves as long as life continues, it is possible to produce as
much energy as envisaged, and they harm the environment to a
lesser extent than fossil fuels, they will not probably achieve industrial efficiency as fast as fossil fuels did [1]. Therefore, although
heavy industry in Eregli continues to use fossil fuels, it is important
that at least the energy demand of households be satisfied with
renewable energy, particularly wave energy in order to have a
clean and healthy environment and produce cheap energy in
Eregli, 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 created
by the effects of storms and winds that are frequently experienced
in the western Black Sea region, carried out practical and theoretical investigation into the subject and emphasized that it is important that the wave energy potential presented by the Akcakoca
shoreline be identified because the region is home to many sectors,
mainly tourism, agriculture and animal husbandry and has transit
connections to major cities. They studied observational data
recorded between 07.00, 14.00 and 21.00 h in previous years
(1996–2000) at Akcakoca Meteorological Observatory of the General Directorate affiliated with the Turkish Meteorological Service.
As a result of studies conducted, total annual wave height of the
Akcakoca shores over 5 years was calculated to be 0.55 m [9]
(Table 8).
In order to calculate the real wave energy potential, it is
necessary to measure wave speed as well. Therefore, the energy
744
H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747
Table 6
NOx emissions released by The Eregli Iron and Steel Plants [27].
Table 9
Main renewable energy sources and their usage forms [1].
Units
Emission
(mg/m3)
Permissible
limits (mg/m3)
Coking plant stack no 1
Coking plant stack no 2
Thermal power station no
Thermal power station no
Thermal power station no
Thermal power station no
Thermal power station no
Lime plant no 1
Lime plant no 2
Lime plant no 3
Sinter
Slab furnace no 1
Slab furnace no 2
Blast furnace no 1
Blast furnace no 2
602
–
456
606
360
382
63
81
100
83
1432
756
214
70
59
500
1
2
3
4
5
800
800
800
597
500
Energy source
Energy conversion and usage options
Hydropower
Modern
biomass
Geothermal
Power generation
Heat and power generation, pyrolysis, gasification,
digestion
Urban heating, power generation, hydrothermal, hot dry
rock
Solar home system, solar dryers, solar cookers
Photovoltaics, thermal power generation, water heaters
Power generation, wind generators, windmills, water
pumps
Numerous designs
Barrage, tidal stream
Solar
Direct solar
Wind
Wave
Tidal
–
Table 7
Particulate emissions (PM) released by The Eregli Iron and Steel Plants [27].
Units
Emission
(mg/m3)
Permissible
limits (mg/m3)
Coking plant stack no 1
Thermal power station no 5
Lime plant no 1
Lime plant no 2
Lime plant no 3
Sinter
Slab furnace no 1
Slab furnace no 2
Blast furnace no 1
8
12
1510
517
10
300
2
2.4
2
250
200
–
Table 8
Observational wave data obtained from The Akcakoca Observatory [9].
Years
Max. wave
height (m)
Average wave
height (m)
Number of waves with a height
of more than 3 m
1996
1997
1998
1999
2000
6
9
6
10
7
0.48
0.54
0.55
0.62
0.49
4
17
10
20
8
Average
7.60
0.54
11.80
potential was calculated parametrically and the wave power
potential of the shores in Akcakoca was found to be (P): P = 690–
2802 Cg (W/m). If wave group velocity (Cg) is assumed to be
10 m/s (36 km/h), wave power potential of the shores in Akcakoca
is found to be the lowest 6 kW/m and the highest 28 kW/m.
Although these semi-empirical results help produce some suggestions, wave velocity, average wave height and period must be measured by means of electronic devices in order to make more
accurate judgments [9]. Considering the existing systems used to
convert wave energy into mechanical and electrical energy, and
investment costs involved, it can be said that the power potential
calculated is sufficient, but not cost-efficient [28]. As systems that
produce electrical energy from sea waves are developed for ocean
shores with a very high wave height, suitable technologies must be
developed for the seas surrounding Turkey [9].
Akpinar and Komurcu [17] studied the quantity of wave energy
resource in deep and shallow waters in the Black Sea and map the
available energy and its monthly and seasonal variations. They
estimated wave parameters for 15 years (1995–2009) and calculated the annual, seasonal, and monthly mean wave energy. The
south-western part of the Black Sea is affected from the waves
more than the eastern part, and identified to possess higher wave
energy and power compared to the eastern part of the Black Sea
and mean annual wave energy resource in the Black Sea is up to
3 kW/m. Levels of significant wave height and wave power in the
western part of the Black Sea are up to 160% and 250% larger than
those in the eastern part of the Black Sea, respectively [17].
The seasonal distribution of storm events in the Black Sea was
assessed by Arkhipkin et al. [29]. They observed wave heights
exceeding 5 m in February and wave heights exceeding 4 m in July.
Arkhipkin et al. [29] calculated average significant wave height is
0.5–0.55 m, maximal significant wave height is 5–5.5 m, maximal
wave length is 55 m, maximal wave period is 7 s and wave height
of 100 year repeatability is 5–6 m at the south-west part of the
Black Sea including close area of Eregli [29].
The Black Sea shoreline is the most efficient region in Turkey as
regards the formation of waves in its seas and their features. Those
regions of Turkey should be identified which have renewable
energy potential and where energy generated can be readily distributed, and the potential energy values of these regions should
be calculated and investments should be made in suitable regions.
Studies conducted in this framework have investigated the energy
capacity of sea waves created by storms and winds that frequently
occur in the western Black Sea region and theoretical and practical
_
work has been carried out on the subject [30]. A TÜBITAKsponsored project (Turkish abbreviation for the Turkish scientific
and technical researches institution) in 2004 involving a model
study initiated in Eregli had to be abandoned due to the lack of
funds [31]. It is evident from Table 9 that main renewable energy
sources are used for various purposes; wave energy is still undergoing 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 in
Eregli in parallel to ever-developing technology reveals that, due to
the necessity of a temperature difference of 20 °C between the surface and water at a depth of 1000 m and pipes 300–400 m in length
and 2.5 in diameter, closed cycle systems have not been found
economic. Open cycle systems, despite their low efficiency, are
preferred because they are advantageous in that they can be used
for producing fresh water and practicing sea food husbandry. Since
nearshore and offshore converters have to be installed in geographically distant locations and accordingly require additional
costs (sea bed cables etc.) and investments to efficiently transmit
the energy produced by systems floating in the middle of the sea,
Eregli is more suitable for wave energy production through shoreline converters rather than other converters, at least in the beginning [32]. In shoreline converters, energy production systems are
installed on the shore or buried. They are easier to built and maintain compared to other converters. In addition, they do not require
H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747
Fig. 5. The oscillating water column system (OWC) [33].
deep water connections or underwater electrical cables. However,
due to the wave regime characterized by less power, they tend to
produce less wave energy. Moreover, these types of converters
cannot become widespread due to limitations such as shoreline
geology, tides and the concern for shoreline preservation. ‘‘oscillating 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 column
of water. As waves impinge upon the device, they cause the water
column to rise and fall, which alternatively compresses and
depressurises the air column. If this trapped air is allowed to flow
to and from the atmosphere via a turbine, energy can be extracted
from the system and used to generate electricity. Energy is usually
extracted from the reversing air flow by Wells’ turbines, which
745
have the property of rotating in the same direction regardless of
the direction to the airflow’’ [33]. As the oscillating water column
systems (OWC), a shoreline converter, a partially submerged structures below sea level that are made of steel or concrete and
extends into the sea, they can be installed on and in alluvium made
up of uncemented sand, clay, silt and conglomerate of Quaternary
age which stretch along the west of Eregli, beach areas composed
of seaside sand and slope wash consisting of clastic rock fragments
occurring in valley bases. Before an oscillating water column system (OWC) is installed in beach areas that offer flat land close to
the sea, plans should be made which put into consideration population density, tourism movement and landscape designing as well
as social life. The flat land which comprises the plains around the
shores of Kepez Stream and Guluc River to south of Goztepe and
the 2.5 km Uzunkum beach on the shores of these plains, and the
flat area between Eregli Iron and Steel Plant and the shoreline
are suitable for oscillating water column (OWC) converters that
would not put much burden on the tourism movement, social life
and landscape in Eregli.
The tapered channel system (TAPCHAN) (Fig. 6), a shoreline
converter 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 feeds into a reservoir constructed on the edge of a cliff. ‘‘Waves enter the wide end
of the channel and, as they propagate down the narrowing channel,
the wave height is amplified until the wave crests spill over the
Fig. 6. The tapered channel system (TAPCHAN) [33].
Fig. 7. The geological structure of the study area [23] and a map showing 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 in
the reservoir returns to the sea via a conventional low head turbine, which generates a stable output due to the storage effects
of the reservoir’’ [33]. With the exception of beach areas, the shores
have a high elevation and consist of step cliffs in Eregli. In fact, the
township has cliffs to the north which are 150 m and, in some
places, as low as 1–2 m. To the northeast, between Koseagzi and
Degirmenagzi cliffs extend landward at an inclination of 10–12°
which have a height of 100–150 m and are composed of limestone
layers. These areas which comprise Baskoy formation composed of
a thin layer of a marl and clayey limestone intercalation with tuffite and sandstone, the Dinlence formation lying over this formation to the south west of these areas and to the north west of
Eregli, which is composed of a thick layer of a massive agglomerate–tuff intercalation, the Liman formation lying to the northwest
of Eregli, which is made up of tuff, agglomerate, rare sandstone and
siltstone, and the Alapli formation lying to the southwest of Eregli,
which is composed of marl, clayey limestone, limestone and sandstone, are all suitable areas for the installation of tapering channel
systems (TAPCHAN) that have a wall height above sea level (Fig. 7).
Yan [34] indicated the expedited transition towards a lowercarbon energy system presented opportunities to ensure energy
security, rebuild national and regional economies, and address
climate change and local pollution [34]. Li and Willman [35] presented results of introducing tidal power in Southern Alaska. They
stated that it is necessary to distribution and transmission analysis
in the future [35]. However it seems unlikely that sea based energy
devices will be able to satisfy the electricity needs of the whole
world, it can form one of a suite of measures necessary to find a
sustainable solving to future energy demands [36]. However wave
energy is a new, rapidly expanding field promising to generate significant amounts of electricity in coastal areas [37]. Owing to the
deterioration of the worldwide environment, the increasing scarcity and high cost of the conventional energy sources (fossil fuels),
renewable energy is currently one of the main areas of research
and investment [38].
Wave measurements in Akcakoca located very close to Eregli [9]
and the studies in whole Black Sea basin [17] show that Eregli is
more suitable for establish a wave measurement station to wave
energy converters. For a analyses and applications of wave converters in Eregli and to help relevant decision makers it is necessary to measure wave velocity, wave period, wave height,
distance between two waves like a other applications about wave
converters. This study has been completed without financial support. Instrumented measurement system is required instead of
observational meteorological and geological measurements. Financial support, specialist team and equipment are required for process measurement and observation. So this study might be used
as 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. Renewable
energy sources satisfy 14% of the world-wide energy demand.
Although wave energy, a renewable energy source, is clean, inexpensive and eco friendly, cannot be a primary energy source and
cannot be stored primarily. Main renewable energy sources are
used for various purposes, whereas wave energy is still undergoing
the processes of design, trial, application and development.
The most efficient region as regards wave formations in the seas
of Turkey and features that these waves have is The Black Sea
shoreline. Although Eregli consumes 17,740,906 m3 of natural gas
and 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 cause
little air pollution. The heavy industry in Eregli still uses fossil
fuels. However, it is important that the energy need of households
alone be met with renewable energy source, particularly wave
energy, for this would not only help achieve a clean and healthy
environment, but also produce clean and inexpensive energy wave.
Considering energy systems that can be installed in Eregli in parallel to ever-developing technology, it is obvious that, due to the
necessity of a temperature difference of 20 °C between the surface
and water at a depth of 1000 m and pipes 300–400 m of length and
2.5 of diameter, closed cycle systems have not been established not
to be ergonomic. Despite their low efficiency, open cycle systems
are preferred to closed ones because they provide the advantage
of being used for producing fresh water and practicing sea food
husbandry.
Wave energy has shoreline, nearshore and offshore converters.
Since near shore and offshore converters have to be installed in
geographically distant locations and thus require additional costs
(sea bed cables etc.) and investments to efficiently transmit the
energy to grid systems that is produced by systems floating in
the middle of the sea, shoreline converters in Eregli, at least in
the beginning, are more suitable for wave energy production compared to other converters.
The study area comprises, in order of age from the oldest to the
youngest, 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 tuffite
sequence with a thin layer, the Dinlence formation (Crd), which
is made up of a massive agglomerate–tuff intercalation, the Liman
formation, which comprises tuff, agglomerate, rare sandstone and
siltstone forming a thick layer, Kale formation (Crkl), which is
made up of a thin-medium layer of intercalated marl, claystone
and tuff, the Sarikorkmaz formation (Crsa), which comprises an
intercalation of sandstone and claystone, and rare khaki tuff gravels, the Alapli formation with a thin-medium layer, composed of
marl, clayey limestone, limestone and sandstone, slope wash composed of clastic rock fragments, and alluvium comprising uncemented sand, silt and gravel and occurring over large areas of
river beds and plain bases.
As the oscillating water column systems (OWC), a shoreline
converter, are a partially submerged structures below sea level that
are made of steel or concrete and extend into the sea, they can be
installed on and in alluvium made up of uncemented sand, clay, silt
and conglomerate of Quaternary age which stretch along the west
of Eregli, beach areas composed of seaside sand and slope wash
consisting of clastic rock fragments occurring in valley bases. The
Uzunkum beach and the flat area between Eregli Iron and Steel
Plants (Erdemir) built in plains and the shoreline are suitable for
oscillating water column converters, for they would not put a
straint on the tourism movement, social life and landscape in Eregli. The Basköy formation lying to the northeast of Eregli, which
consists of a thin layer of a marl-clayey limestone intercalation
with tuffite and sandstone, the Dinlence formation to the northwest, composed of a massive intercalation of agglomerate and tuff,
the Liman formation, made up of tuff, agglomerate, rare sandstone
and siltstone, and the Alapli formation to the southwest which is
made up of marl, clayey limestone, limestone and sandstone are
all regions that are suitable for the installation of tapered channel
system (TAPCHAN) with a wall height above sea level.
Since systems for electrical energy production from sea waves
have been developed for ocean shores with very high wave height,
technologies must be developed that can be applied on the shores
of the seas surrounding Turkey. Those regions in Turkey must be
identified that represent renewable energy potential and where
the energy produced can be readily transmitted to main power
H. Keskin Citiroglu, A. Okur / Applied Energy 135 (2014) 738–747
grids, and the potential energy that these regions have must be calculated and investments should be made in suitable in suitable
regions in the soonest possible time.
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