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L. Liberti et al. / Renewable Energy 50 (2013) 938e949

Fig. 8. Distribution of average power per unit crest in the Mediterranean between 2001 and 2010. Wave power values are tabulated for selected sites marked by circles in Table 8.

wave directions as described by Mardia and Jupp [29]. Given a set of significant period. Te represents the period of a sinusoidal wave
having the same energy content of the sea state [31]. When sea
n model directions yi and corresponding measures xi the directional
bias (bias) and directional variance (var) of the residuals yiÀxi are state is described by the directional wave energy density spectrum

calculated as: function S(f,q), Te has the expression:

S ¼ 1 Xn (6) Z2p ZN
n sinðyi À xiÞ;
f À1Sðf ; qÞdf dq
i¼1
mÀ1
Xn Te ¼ m0 ¼ 00 : (12)
cosðyi À xiÞ;
C ¼ 1 (7) Z2p ZN
n i¼1
Sðf ; qÞdf dq

00

R ¼ 2 þ S2 1 ; (8) Equation (12) is equivalent to the definition of the integral wave
C 2 (9) parameter Te calculated by the WAM code that was used in our
calculations [17].

bias ¼ arctan S=C ;

var ¼ ÀÁ (10) 3.1. Wave power distribution in the Mediterranean
1ÀR :
Fig. 8 shows a map of the available wave power flux per unit
Table 7 shows for each buoy the values of the computed crest averaged over the entire 10 years simulation period in the
statistics. Since the wave direction is not well defined for calmer sea Mediterranean. The most productive area, showing average values
states, we excluded from the analysis all the records where the
buoy Hs was less than 1 m. The agreement between the model and Table 8
buoy direction seems satisfactory for the scope of the present study. Average wave power flux Jmean and average annual energy flux Emean over the entire
Circular biases between 10 and 15 are found only at Catania, simulation period at selected sites along the coast of the Mediterranean as shown in
Ortona and Mazara del Vallo buoys and the values of the circular Fig. 8. Values were extracted from the second cell offshore.
variance of the residuals are on the lower end of the admissible
range [0,1] with the highest value found at Ancona. The main Site Location Lon. Lat. Depth Jmean Eannual
directional characteristics of the wave climate are well described by
the model as shown in Figs. 6 and 7 where the model and buoy (m) (kW/m) (MWh/m)
frequency distribution of average wave direction are compared.
1 Cabo de Palos (Es) À03304500 373403000 121 3.91 34.25
95.48
2 Menorca (Es) 4 150 000 40 40 3000 65 10.90 46.78
56.68
3 Cabo Creus (Es) 32601500 421903000 439 5.34 26.02
73.93
4 Hyères (Fr) 61101500 425301500 1476 6.47 30.70
32.41
3. Model results and discussion 5 Livorno (It) 101101500 433004500 83 3.24 43.01
62.20
6 Ajaccio (Fr) 8 300 000 41570000 786 8.44 45.20
19.80
The results of the model were used to prepare wave energy 7 Napoli (It) 14703000 403004500 782 3.51 33.55
maps of the entire Mediterranean and to analyze the wave energy 35.22
availability and variability along the Italian coast. Following [30], in 8 Crotone (It) 171804500 39004500 615 3.70 46.43
deep water, the available energy flux per unit crest can be 57.73
expressed as: 9 Kefallonia (Gr) 20150000 38120000 1512 4.91 49.76
81.03
10 Ag. Gramvousa (Gr) 233304500 35420000 374 7.10 90.49
45.11
11 Skyros (Gr) 24450000 384903000 269 5.16

12 Gelydonia Burnu (Tr) 302601500 36801500 444 2.26

13 Peyia (Cy) 321101500 345301500 1290 3.83

rg2 14 Haifa (Il) 344804500 324504500 252 4.02
64p
J ¼ Te Hs2 (11) 15 Ras El-Kanayis (Eg) 275203000 311903000 420 5.30

16 Ras Al Hilal (Ly) 233304500 35420000 374 6.59

17 Misrata (Ly) 151101500 323004500 161 5.68

where J is the energy flux in Watt per meter of wave crest, g is the 18 Ras Angela (Tn) 94101500 37270000 250 9.25

gravity acceleration, r the sea water density assumed to be 19 Cap Bougaouni (Dz) 62601500 37120000 2354 10.33
r ¼ 1025 kg/m3, Hs the significant wave height and Te the wave
20 Orano (Dz) À02203000 36004500 1428 5.15