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Sustainability 2017, 9, 106 3 of 19

Sustainability 2017, 9, 106 3 of 19
such sources as biomass or water. Currently, the European Parliament passed a law on hydrogen
vehicles’ homologation in an effort to protect the environment in urban centers.
The law applies not only to the development of fuel cell vehicles but also to the development of
hydrogen filling stations and the necessity of producing hydrogen in sustainable ways [7]. Hydrogen
The law applies not only to the development of fuel cell vehicles but also to the development of
hydrogen filling stations and the necessity of producing hydrogen in sustainable ways [7]. Hydrogenr
can be produced from biomass through several thermochemical processes, such as gasification o
pyrolysis and biological processes. One of the possible renewable energy sources to be used to
can be produced from biomass through several thermochemical processes, such as gasification or
produce hydrogen is water, through electrolysis or thermochemical processes. In this paper, we
pyrolysis and biological processes. One of the possible renewable energy sources to be used to produce
consider the hydrogen production based on the electrolysis process, since it requires only the
hydrogen is water, through electrolysis or thermochemical processes. In this paper, we consider the
electrical energy supply, that can be easily satisfied by using several renewable energy sources.
hydrogen production based on the electrolysis process, since it requires only the electrical energy
The following Section 2 analyzes the energy potential of wind, biomass and sea wave sources in
supply, that can be easily satisfied by using several renewable energy sources.
the western Sicilian context. In order to exploit the wave source, an energy converter is presented.
The following Section 2 analyzes the energy potential of wind, biomass and sea wave sources
The Section 4 evaluates the hydrogen demand in order to replace the diesel-powered buses in Trapani
in the western Sicilian context. In order to exploit the wave source, an energy converter is presented.
The Section 4 evaluates the hydrogen demand in order to replace the diesel-powered buses in Trapanir
with electrical buses equipped with fuel cells. The three different energy sources are considered fo
the hydrogen production. Finally, an economic and environmental evaluation is presented.
with electrical buses equipped with fuel cells. The three different energy sources are considered for the
hydrogen production. Finally, an economic and environmental evaluation is presented.
2. Renewable Energy Sources in Trapani
2. Renewable Energy Sources in Trapani
2.1. Wind Source
2.1. Wind Source
Firstly, we analyze the wind resource. In Sicily, this source is characterized by high potential
Firstly, we analyze the wind resource. In Sicily, this source is characterized by high potential levels
levels and the production of electrical energy from wind turbines represents [8] nowadays an
and the production of electrical energy from wind turbines represents [8] nowadays an important
important percentage of the overall electrical energy production in loco [9]. Wind source was
percentage of the overall electrical energy production in loco [9]. Wind source was accurately studied
accurately studied by CESI (Centro Elettrotecnico Sperimentale Italiano) and Physics Department of
by CESI (Centro Elettrotecnico Sperimentale Italiano) and Physics Department of University of Genova.
University of Genova. Thanks to these studies, the Italian Wind Atlas (Atlante Eolico Italiano) is now
Thanks to these studies, the Italian Wind Atlas (Atlante Eolico Italiano) is now available [10]: it is a very
available [10]: it is a very useful online tool, that can be used to evaluate the theoretical electrical
useful online tool, that can be used to evaluate the theoretical electrical energy production from wind
energy production from wind turbines. The web page reports a GIS (Geographic Information System)
turbines. The web page reports a GIS (Geographic Information System) map, in which the average
map, in which the average wind speed at different levels from the soil is expressed: 25 m, 50 m, 75 m,
wind speed at different levels from the soil is expressed: 25 m, 50 m, 75 m, 100 m from the soil. In this
100 m from the soil. In this work, we consider only the average wind speed at 50 m from the soil,
work, we consider only the average wind speed at 50 m from the soil, because the particular type of
because the particular type of wind turbine selected will be able to work at this distance. Greater
wind turbine selected will be able to work at this distance. Greater distances involve the necessity to
distances involve the necessity to introduce a higher and more visible wind turbine, while shorter
introduce a higher and more visible wind turbine, while shorter distances reduce the electrical energy
distances reduce the electrical energy production. Moreover, the authors focused their attention on
production. Moreover, the authors focused their attention on the on-shore wind source in order to not
the on-shore wind source in order to not use sea areas, which will be exploited with a Point Absorber,
use sea areas, which will be exploited with a Point Absorber, proposed in the Section 3. Moreover, the
proposed in the Section 3. Moreover, the Italian laws are a serious obstacle for the potential
Italian laws are a serious obstacle for the potential installation of off-shore wind farms. Figure 2 shows
installation of off-shore wind farms. Figure 2 shows the average wind speed in Sicily at 50 m above
the average wind speed in Sicily at 50 m above ground level.
ground level.

Figure 2. Average wind speed in Sicily at 50 m above ground level.
Figure 2. Average wind speed in Sicily at 50 m above ground level.
Particularly, most of the Sicilian lands are characterized by an average wind speed comprised
between 5 and 6 m/s. Additionally, the province of Trapani presents higher values, comprised