This document discusses the potential for ocean energy resources in the Hellenic seas. It analyzes wave and current data from several basins in the region and finds the East Aegean has the highest average current velocity at 0.17 m/s. Wave energy is highest in the South Aegean, with an average of 1.09 kJ/m2. Suitable areas for wave energy extraction are identified as Kassos, Karpathos, and Antikythera Islands due to high wave power reinforced by winds and coastal geography. While current velocities are moderate, further high-resolution modeling and data collection is needed to better identify locations with potential for marine energy development.

1. NATIONAL AND KAPODISTRIAN UNIVERSITY OF ATHENS
FACULTY OF PHYSICS
DIVISION OF ENVIRONMENTAL PHYSICS - METEOROLOGY
Ocean Physics and Modelling Group

2. Oceans:
 Colossal reservoir of energy
 Highest energy density among all the renewables
 Only the 0.02% of the available energy would satisfy the present world
energy consumption (M. Amundarain et al., 2010)
Ocean energy resources:
 Marine currents
 Waves
 Tides
 Temperature gradients (OTEC)
 Salinity Gradients (Osmotic
Power)
(IEA-OES, 2009)

3. Seagen
HS1000 Open Hydro
Stingray
Rotech Tidal Turbine
Deep Green

4. Wave Dragon (Offshore)
AWS
(Offshore)
Mighty Whale (Offshore)Anaconda (Offshore)
Aqua Buoy
(Offshore)
Pelamis (Offshore)
OWC (Shoreline)
Oceanlinx (Nearshore)
WaveRoller (Nearshore)
TAPCHAN (Shoreline)
Point Absorber
Oyster (Nearshore)
SSG
OWC (Shoreline)

5. Scope:
 Investigation of the power from marine currents and waves in the Hellenic seas.
 Identification of possible suitable sites for electricity production.
Data and Methods:
 Analysis of wave and hydrodynamical model outputs.
Operational
Forecasting
Systems
3-hourly wave data
1/1/2004 - 31/12/2010
Parameters used:
Significant wave height
(Hs) and direction
Weekly circulation data
2/3/2007 - 30/4/2010
Parameters used: Zonal
and meridian horizontal
velocities for the surface
layer of 10 meters.
TRITON (1o/10×1o/10)
ALERMO (1o/30×1o/30)

6. • Wave energy density (J/m2)
ρ=1024kg/m3 the fluid density
g=9.81m/s2 the acceleration of gravity
Ηs (m) the significant wave height
• Power from marine currents (W)
ρ=1024kg/m3 the fluid density
A=1 m2 the cross sectional area of the turbine
V (m/s) the fluid stream velocity.
VAP
3
2
1

(Fraenkel, 2002))

7. Segmentation of study area into four sub-
basins:
 North Aegean: 22.6-27.8°E & 38.6-41.2°Ν
 East Aegean:26-30°Ε & 33-38.6°Ν
 South Aegean: 22.6-26°E & 33-38.6°N
 Ionian Sea: 20-22.6°E & 33-41.2°N
20-30°Ε & 33-41.2°Ν
(1/10°x1/10°)
IONIAN
SEA
NORTH AEGEAN
SOUTH
AEGEAN
EAST
AEGEAN

8. (Soukissian et al.,2008)

12. Study sub-
basins
Parameter Mean Max Min Std
East Aegean V (m/s) 0.170 1.112 0 0.006
P (KW/m2) 0.008 0.704 0 0.001
South Aegean V (m/s) 0.139 1.087 0 0.005
P (KW/m2) 0.005 0.657 0 0.004
Ionian Sea V (m/s) 0.143 1.071 0 0.007
P (KW/m2) 0.005 0.629 0 0.004
North Aegean V (m/s) 0.075 1.000 0 0.010
P (KW/m2) 0.002 0.513 0 0.004

17. Study sub-
basins
Parameter Mean Max Min Std
North Aegean Hs (m) 0.630 10.500 10-5 0.038
E (KJ/m2) 0.499 69.219 6.28·10-11 0.038
South Aegean Hs (m) 1.086 11.800 10-5 0.029
E (KJ/m2) 1.093 87.420 6.28·10-11 0.029
East Aegean Hs (m) 1.172 11.800 2.47·10-5 0.034
E (KJ/m2) 1.236 87.420 3.83·10-10 0.034
Ionian Sea Hs (m) 1.178 8.890 9.18·10-5 0.027
E (KJ/m2) 1.309 49.619 5.29·10-9 0.027

20. days/yearThreshold (1<Hs<5) Threshold (1<Hs<5)
Threshold (1<Hs<5)
Threshold (1<Hs<5)

21. Offshore
Wave Energy
1. Distance
from shore
2. Installation
depth

22. Calculation of the optical horizon considering the effect of atmospheric refraction and the
curvature of earth:
Where d: is the distance from shore (Km), h1: height of an hypothetical observer (m),
h2: height of a typical wind turbine (m). Assuming that h1=1.7m και h2=40m the distance to
the horizon is approximately 30Km.
)21(2.4min hhd 

24. Ocean energy in our region is therefore a promising source of
renewable energy with high energy density and predictability.
Marine current power seems to be reinforced along the different
circulation patterns, detected in the Hellenic seas, whereas its
temporal variability appears to be influenced by the wind regime, the
BSW inflow as well as by the seasonality that characterizes the
several circulation features.
The exploitation of marine currents is not considered economically
viable yet as the current velocity presents relatively moderate values
and the minimum operational threshold of today’s turbines, is still
too high.
Wave energy even though it displays lower values than in other
European countries, it may be harnessed and thus contribute to the
energy independence of several islands of the Aegean and
furthermore to ensure potable water through desalination.
Suitable areas that combine high levels of power and efficiency on a
mean annual basis, are considered to be Kassos Isl., Karpathos Isl.
and Antikythera Isl. where the wave field seems to be reinforced by
the strong winds, the long fetch lengths and the channeling effect.

25.  Extensively study is required focused on:
 potential sites
 coastal regions where wave transformation may
lead to “hot spots” generation
 Euripus Straights where high current velocities
have been measured.
 Implementation of a high resolution numerical model
 Combination with satellite data
 Combination with in situ data