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At the same time, the most populated island is Pantelleria although its demographic density is not
actually the highest. The less populated island is Linosa. Lampedusa and Favignana reach the
highest population density values, as shown in Tab. 1.
Figure 1 shows how the examined islands may be effectively grouped in clusters, in order to
make possible a meaningful comparison of the outputs of the analyses. In particular, blue circles
identify islands showing similar characteristics in terms of number of inhabitants, while red
circles define sets of islands sharing the same climatic features in terms of HDD.

Figure 1. Clusters of islands according to population and climatic criteria.

Other issues concerning the feasibility of district heat networks deal with the peculiar orography
of islands.
Figure 2 highlights these issues by showing: the position of the power plant and the distance
from the most densely populated areas; the possible “DH main” line sketched from the power
plant to the urbanized area and, by the use of additional elements (blue and white circles with
numbers, as depicted in the legend), the number and location of spot users belonging to the
tertiary sector (e.g. hotels, schools). Potential ”outliers”, such as airports and prison, are also
highlighted in Lampedusa, Pantelleria and Favignana districts. In general, it is worth noting
that in each island we may distinguish between a relatively dense “urban area” (indicated in
Figure 2) and large zones having a diffuse “low density” urbanization where the heat load
density is evidently too low to justify any possible hot/warm/cold fluids distribution. For these
reasons these areas are not considered in the rest of the analysis as concerns the evaluation of
energy loads. Moreover, looking at islands orography, it is worth noting that Pantelleria and
Isola del Giglio are characterized by the presence of hills in the area of main interest for the
project. This represents an additional barrier and influence the definition of the “useful area”
to be evaluated for the feasibility of a District Heating/Cooling network.
Finally, the pre-feasibility study cannot neglect the effects on the big asimetry during the year of
load profiles strongly influenced by the touristic vocation of the islands. In particular, it has been
noticed that almost 50% of houses in the Pantelleria, Lampedusa and Favignana, 30% in Isola
del Giglio and 70% in Ustica are not generally occupied during winter [19] while touristic
reports [20] confirm that the peak of touristic fluxes are everywhere registered during August.

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