Page 22 - Beccali_Ciulla_alii_2016

0332-22

and heat production (fixed equal to 0.46 and 0.90 by the referenced National legislation),
and ECHP, HCHP and FCHP represent the Electricity and useful Heat produced and the Fuel
consumed in “efficient CHP mode”, according to the provisions of Directive 2004/8/EC
[36]. It is assumed that the whole amount of heat cogenerated is produced in “efficient
CHP” mode; this condition is realistic, due to the low reference efficiency recommended
for diesel-fuelled units.

Table 7. Synthetic indicators of economic viability for the scenarios with and without incentives

NPV [k€] DPT [years] PI [dimensionless]
Island Without With Without With Without With
incentives incentives incentives incentives incentives incentives
Lampedusa 2686.9 5458.7 17.4 9.8 0.405 1.199
Favignana -1199 651.8 Not available 21.1 -0.271 0.231

Pantelleria 687.7 1863.8 20.2 11.1 0.225 0.852
Ustica 23.9 535.5 > 30 13.7 0.02 0.659
Giglio -21.7 396.7 Not available 13.8 -0.023 0.651

Linosa -194.8 52.1 Not available 24.2 -0.324 0.135

The results are shown in Tab. 7 and their comparison with the detailed data provided for each
island in the previous sections allow us to draw some interesting considerations:
1. In case of absence of any support mechanism, in all the examined islands the investment for
the “CHP retrofit + DH network installation” is not economically viable. This is an obvious
consequence of the low heat density, associated in its turn with the limited demographic
density and the prevalence, in the residential sector, of small buildings where space heating
and cooling needs are prevalently covered by small split systems;
2. If sufficient incentives are provided, justified by the aforementioned public interests in
increasing the average energy conversion efficiency of the existing power units, positive
NPVs over the expected plant life cycle span may be achieved. Actually, even in this more
favourable scenario the attractiveness of investment remains low, due to the Payback Time
often above 10 years and the Profitability Index assuming values below 1 (this value is
usually assumed as a minimum threshold for economic viability);
3. The influence of geographical/climatic and demographic variables on the feasibility of the
examined solutions is easy-to-examine. Differently than in the analysis of urban DH
projects, the climatic conditions (represented by the number of Heating Degree days
presented in Table 1) do not seem to play a primary role; despite its largely highest HDD,
the “Isola del Giglio” resulted scarcely promising as concerns the feasibility of “CHP retrofit
+ DH network installation”. Conversely, the number of residential/permanent inhabitants
seems to favour the attractiveness of this technical solution: the two most populated islands
(see Figure 1), Lampedusa and Pantelleria, achieved the highest Profitability Index and the
lowest DPT (which resulted below 12 years for the scenario “with incentives”). Ultimately,
the relative position between the power plant and the most densely populated area resulted
to be another key factor. The island of Favignana, for instance, in spite of its high number of
nd
permanent inhabitants, resulted to be 2 least attractive among the examined islands (see
Table 7), being the unique having the power plant being located at high distance from the
most densely populated area, as evident in Figure 2.

22