Page 3 - Vannucchi_Cappietti_2016

Sustainability 2016, 8, 1300 3 of 21

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hotspots [20–37]. At the oceanic global scale, the richest wave power areas are between 40 and
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60 latitude of both hemispheres [10].
Concerning Europe, previous studies [1,4–11] proved that the maximum-yearly mean
wave-energy values are on the western coast of Scotland and Ireland, where 70 kW/m are achieved [4,9].
In North America, the peaks are in Oregon, British Columbia and Alaska where it ranges from 40 kW/m
to 60 kW/m. In the southern hemisphere, the highest values occur on the Pacific coasts of southern
Chile (around 100 kW/m [4,9]), western South Africa (around 50 kW/m [4,9]), southwest and southern
coasts of Australia [12] and New Zealand (around 100 kW/m [4,9]). It is worth noting that although the
wave power values in the Northern and Southern Hemispheres are similar, the Southern inter annual
variation is considerably lower [5,20] so it may foster the exploitation of the wave energy resource.
In the case of Mediterranean Sea, the first assessment of the offshore wave energy was developed
in 1996 [13] pointing out wave power values close to 1 kW/m in the northern area of the Adriatic
Sea, and 6 kW/m off the western area of Sardinia and Sicily Italian islands. In 2004, the interest on
the Mediterranean Sea started to increase when a consortium of six companies published a wave
power atlas [14], with spatial resolution of about 50 km, showing offshore wave potentials in the
range between 0.75 kW/m in the northern area of the Adriatic Sea and 14.75 kW/m in the western
area of Sardinia and Corsica islands [15]. In 2011, Vicinanza et al. [16], by using wave data collected
by the Italian wave buoys network, obtained yearly mean values lower than 2 kW/m in the central
Adriatic Sea and equal to 9.1 kW/m at the Alghero wave buoy on 100 m of water depth in the north
west offshore facing the Sardinia island. In 2013, Liberti et al. [17] assessed the wave power through
numerical simulation hindcasting of the whole Mediterranean Sea for the period 2001–2010, and their
results show that the most energetic area is in the Western Mediterranean between the Balearic Islands
and the western coast of Sardinia where it reaches values above 15 kW/m. Sierra et al. in 2014 [18]
studied the wave energy resources around Menorca Island (Mediterranean Sea) finding yearly mean
wave power close to 8.9 kW/m. In 2016, Besio et al. [19] followed the line opened by Liberti et al. [17]
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but increased the resolution of the atmospheric forcing from 1 /4 to 1 /10 , extending the range of
the numerical simulation from 10 to 35 years (from 1 January 1979 to 31 December 2013) and decreasing
the time step for the recording of wave characteristics to 1 h instead of 3 h. The Besio et al. [19] results
are similar to those obtained by Liberti et al. [17]. In summary, these previous findings show that the
offshore mean energy flux in the Mediterranean Sea has values between 1 kW/m and 2 kW/m in the
central and northern area of the Adriatic Sea and between 10 kW/m and 20 kW/m in the offshore
western area of the Sardinia and Corsica Islands.

2.2. Assessment of the Nearshore Potential
The assessment of the energy potential at coastal sites and the identification of the hotspots
are frequently obtained by means of the propagation of offshore values toward the nearshore.
Although direct measurements at coastal areas are possible, in practice, due to the need for detailed
knowledge in terms of space resolution, the use of numerical modeling is imposed. Generally,
the methodology is based on offshore wave data used as boundary conditions for the numerical
modeling of nearshore wave propagation that can be calibrated and validated using coastal buoy
measurements [21–24]. Some authors [25–31] propagated the most significant three or five wave
cases representing winter/autumn average condition, a summer/spring average condition and a
particularly energetic situation. Other authors [20,22,23,32–37] propagated the whole events in the
time series of the offshore numerical model or the offshore wave buoy measurements and estimated
the available nearshore wave power. For the Mediterranean nearshore, the wave power in the western
side of Sicily has been estimated to be close to 8 kW/m by Iuppa et al. [23] and 5 kW/m by Monteforte
et al. [32]. Iuppa et al. [23] also found a yearly mean wave power in the range 4–6 kW/m in the Strait
of Sicily and 2–3 kW/m in its north and east sides. Along the north western Sardinia Island (Italy),
Vicinanza et al. [33] pointed out values between 3.8 kW/m and 10.9 kW/m. For the western part of
the Black Sea, Akpınar and Kömürcü [34] estimated values around 3 kW/m while on the Eastern