Page 8 - Franzitta_et_alii_2017

Sustainability 2017, 9, 106 8 of 19
Sustainability 2017, 9, 106 8 of 19

Figure 8. Biomass surplus as a function of the distance of the ATM bus depot, in the province
Figure 8. Biomass surplus as a function of the distance of the ATM bus depot, in the province of Trapani.
of Trapani.
2.3. Sea Wave Source
2.3. Sea Wave Source
Sea wave source represents nowadays an unused renewable source, despite the high levels
Sea wave source represents nowadays an unused renewable source, despite the high levels of
of exploitable energy [12]. This consideration assumes greater importance, especially in this case
exploitable energy [12]. This consideration assumes greater importance, especially in this case study
study of the province of Trapani. In fact, as exposed in [12], the higher levels of wave energy in the
of the province of Trapani. In fact, as exposed in [12], the higher levels of wave energy in the
Mediterranean Sea are identified in the western coasts of Sardinia and Sicily, with an average off-shore
Mediterranean Sea are identified in the western coasts of Sardinia and Sicily, with an average off-
wave power greater than 5 kW/m [13]. So, these particular sites are the best ones along the Italian
shore wave power greater than 5 kW/m [13]. So, these particular sites are the best ones along the
coastline in order to use the new conversion device here proposed. The main parameters through
Italian coastline in order to use the new conversion device here proposed. The main parameters
which wave energy is defined are significant wave height H s (measured in meters); peak period T p
through which wave energy is defined are significant wave height (measured in meters); peak
(measured in seconds); and main direction D p . The first one represents the average height of the

period (measured in seconds); and main direction . The first one represents the average height
highest
third of waves, while the second one is highest value of the period measured in the recording

of the highest third of waves, while the second one is highest value of the period measured in the
time. These parameters were collected thanks to the wave buoys of the Rete Ondametrica Nazionale
(RON), which operated from 1989. Additionally, the data obtained through the wave buoys were
recording time. These parameters were collected thanks to the wave buoys of the Rete Ondametrica
used to confirm the values carried out by simulating software, which used wind data as input. In
Nazionale (RON), which operated from 1989. Additionally, the data obtained through the wave
this way, it was possible to describe wave energy potential along the Sicilian coastline in more detail.
buoys were used to confirm the values carried out by simulating software, which used wind data as
input. In this way, it was possible to describe wave energy potential along the Sicilian coastline in
Furthermore, the use of GIS technology (see Figure 9) is able to identify simultaneously the wave
source and the restricted areas in which this source will not be exploited (for example, due to the
more detail. Furthermore, the use of GIS technology (see Figure 9) is able to identify simultaneously
presence of particular environmental and maritime constraints). Particularly, Figure 9 shows the
the wave source and the restricted areas in which this source will not be exploited (for example, due
presence of maritime constraints along the islands of Favignana, Marettimo and Levanzo. According
to the presence of particular environmental and maritime constraints). Particularly, Figure 9 shows
to the average wave potential, the coastlines of the province of Trapani can be divided into two parts:
the presence of maritime constraints along the islands of Favignana, Marettimo and Levanzo.
the northern and the southern part. The first one is globally characterized by a wave power comprised
According to the average wave potential, the coastlines of the province of Trapani can be divided
between 5 and 6 kW/m, while the second one is characterized by values comprised between 6 and
into two parts: the northern and the southern part. The first one is globally characterized by a wave
7 kW/m. In this text, an annual wave power of 5 kW/m is cautiously fixed for the northern part of the
power comprised between 5 and 6 kW/m, while the second one is characterized by values comprised
coastlines and 6 kW/m for the southern part.
between 6 and 7 kW/m. In this text, an annual wave power of 5 kW/m is cautiously fixed for the
Moreover, the main wave direction is north-west [12], thanks to the exposition to the wider fetch.
northern part of the coastlines and 6 kW/m for the southern part.
The correct position of the wave buoys array will have to consider this characteristic, in order to avoid
Moreover, the main wave direction is north-west [12], thanks to the exposition to the wider fetch.
interference phenomena. Finally, wave source appears to be higher during the winter season and lower
The correct position of the wave buoys array will have to consider this characteristic, in order to avoid
during the summer season. The issue connected to the variability of this source can be overridden
interference phenomena. Finally, wave source appears to be higher during the winter season and
through the use of appropriate storage tanks.
lower during the summer season. The issue connected to the variability of this source can be
overridden through the use of appropriate storage tanks.