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Installed capacity

In order to maintain an appropriate safety of supply, adequate levels of redundancy are needed in
case of a failure for a producing unit; also, due to the need for a more flexible operation to follow
the highly fluctuating loads, the installation of several smaller diesel engines is usually preferred
to the installation of one or two large generators. In Table 2 details on the installed capacity, the
waste heat production rate (values are calculated at a 75% maximum load, following the
suggestions received by plant owners about the typical operating strategy adopted) and the
number of individual units installed are given. As concerns the heat production rate, low
temperature waste heat from the cooling jacket water circuits is distinguished by high-grade heat
from exhaust gases.

Table 2. Technical data concerning the power generation systems

Installed Low temp. waste High temp. waste Number of units installed to
Island
capacity [MWe] heat rate [MWt] heat rate [MWt] fraction the overall capacity
Lampedusa 22.56 6.67 8.63 8
Pantelleria 25.03 7.40 9.65 8
Favignana 9.62 4.74 3.71 7
Ustica 5.87 2.88 2.25 5
Giglio 8.19 4.03 3.16 7
Linosa 2.61 1.29 1.01 6

METHODOLOGY

(i) The assessment of energy loads
The methodology discussed in this section was applied to all the examined islands. All
potential users in the territory were grouped in suitable clusters, whose limits were defined
looking at the actual spatial distribution of buildings. The methodology requires determining,
for each spatial cluster, an overall monthly energy demand as well as its shares for two main
categories: (i) residential users (usually grouped in quite omogenous areas) and (ii) spot users
of the tertiary sector. In order to provide a reliable assessment of aggregated energy loads,
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specific energy loads (referred to m of building area or to occupant) were preliminarily
calculated. Thus an integration over the set of buildings located in each specific cluster was
carried out. In particular, footprint area was used as reference unit for residential users. For
this user category the final energy demand was calculated by means of dynamic building
simulation software. The specific energy demand of spot users refers to literature values. H/C
energy needs for schools and prison have been referred to their built volume while DHW
energy needs for hotels depends on the number of beds being these values reported in many
reports/standards usually used for rapid energy audits. Energy demand of “outliers” has been
assessed from available energy audits.
Residential energy demand has been estimated using the EnergyPlus software [21] doing
simulations for a set of reference buildings . Their geometrical and constructive characteristics
have been defined from the information available in the ISTAT Census database 2011 and
from the Report 2/2003 issued by the Thermo technic Italian Committee (Comitato
Termotecnico Italiano - CTI) [22].
In particular, information about building age and construction typology has been extracted
from the ISTAT database, available for each island, and have been arranged and crossed with

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