Page 4 - Franzitta_et_alii_2017

Sustainability 2017, 9, 106 4 of 19

Sustainability 2017, 9, 106 4 of 19
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 between
between 6 and 7 m/s, with a maximum of 8 m/s in the coastlines. This is due to the higher fetch in
6 and 7 m/s, with a maximum of 8 m/s in the coastlines. This is due to the higher fetch in which the
which the wind is able to blow. So, Trapani is an excellent place to adequately exploit the wind source.
wind is able to blow. So, Trapani is an excellent place to adequately exploit the wind source.
Figure 3 shows the GIS map of the annual theoretical energy production by wind in Sicily. Most
Figure 3 shows the GIS map of the annual theoretical energy production by wind in Sicily.
of Sicily shows an average production between 1500 and 2000 MWh/MW, while the values shown in
Most of Sicily shows an average production between 1500 and 2000 MWh/MW, while the values
the province of Trapani remain higher. It is marked by values comprised between 2000 and 2500
shown in the province of Trapani remain higher. It is marked by values comprised between 2000 and
MWh/MW, with a maximum of 3000 MWh/MW in the coastlines. Prudently, an average value of 2000
2500 MWh/MW, with a maximum of 3000 MWh/MW in the coastlines. Prudently, an average value
MWh/MW is fixed in this text.
of 2000 MWh/MW is fixed in this text.

Figure 3. Energy production in Sicily at 50 m above ground level.
Figure 3. Energy production in Sicily at 50 m above ground level.

2.2. Biomass Source
2.2. Biomass Source
As regards the biomass resource, we consider the installation of a power plant with a rated
As regards the biomass resource, we consider the installation of a power plant with a rated power
power of 1.2 MW (electrical output). The biomass power station is composed of eight small ORC
of 1.2 MW (electrical output). The biomass power station is composed of eight small ORC (Organic
(Organic Rankine Cycle) units, each one having a rated electrical output equal to 150 kW [11]. This
Rankine Cycle) units, each one having a rated electrical output equal to 150 kW [11]. This kind of plant
is able to use several types of biomass, for example straw, pruning residues of olives and vineyards.
kind of plant is able to use several types of biomass, for example straw, pruning residues of olives
Before the use, the biomass is dried and converted into woodchips and pellets.
and vineyards. Before the use, the biomass is dried and converted into woodchips and pellets.
The annual biomass consumption of the power plant is estimated at about 13,600 t/year,
The annual biomass consumption of the power plant is estimated at about 13,600 t/year,
considering a lower heating value (LHV) equal to 17 MJ/kg, an electrical efficiency fixed to 16%
considering a lower heating value (LHV) equal to 17 MJ/kg, an electrical efficiency fixed to 16% and
a boiler efficiency fixed to 85% [11]. [11].
and a boiler efficiency fixed to 85%
Based on the information given below, we will try to identify a suitable site for the installation
Based on the information given below, we will try to identify a suitable site for the installation of
a biomass power plant, in the city of Trapani. The biomass catchment area is selected according to
of a biomass power plant, in the city of Trapani. The biomass catchment area is selected according to
these conditions:
these conditions:
 collection of at least 50% of biomass from straw, sufficient to cover 30% of the biomass demand
• collection of at least 50% of biomass from straw, sufficient to cover 30% of the biomass demand of
of the power plant;
the power plant;
 collection of at least 50% of biomass from pruning residues of olives and vineyards, sufficient to
• collection of at least 50% of biomass from pruning residues of olives and vineyards, sufficient to
cover 70% of the biomass demand of the power plant.
cover 70% of the biomass demand of the power plant.
The analysis firstly evaluates the territory of Trapani, having a surface of 3555 ha at the northern
The analysis firstly evaluates the territory of Trapani, having a surface of 3555 ha at the northern
part of the town and 25,500 ha at the southern part. The following Figure 4 shows the land uses in
part of the town and 25,500 ha at the southern part. The following Figure 4 shows the land uses in the
the territory of Trapani. The greatest part of the territory is used for cultivation, in particular 42.8%
territory of Trapani. The greatest part of the territory is used for cultivation, in particular 42.8% for
for extensive farming and 31.8% for vineyards.
extensive farming and 31.8% for vineyards.