Page 15 - Franzitta_et_alii_2017

Sustainability 2017, 9, 106 15 of 19

maintenance costs can be found. The evaluation of the investment costs for hydrogen production can
be easily realized, because all components are already used in the chemical industry.
In order to evaluate the economic viability, the discounted cash flow is calculated in two
different hypotheses:

A. In this hypothesis, we take into account the initial investments of the biomass power plant, wind
farm, wave farm, and hydrogen station. As virtual annual income, we consider the avoided
purchase of fossil fuel.
B. In this hypothesis, we consider only the installation of the hydrogen station, run by purchasing
electrical energy from the grid. Similarly, as virtual annual income, we consider the avoided
purchase of fossil fuel.

The discounted cash flow is evaluated by the following equation:

n n 1 + ε i
DCF = −I 0 − ∑ I i i + Fc f uel − Ec energy ∑ (1)
i = 1 (1 + τ) i = 1 1 + τ

Where I 0 is the initial investment, I i the annual costs for operative and maintenance costs, F is the
avoided annual diesel consumption, E is the annual energy required to produce hydrogen (this term
is considered only in the hypothesis B), c f uel and c energy represent respectively the unitary costs of
electrical fuel (1.40 €/L) and energy (170 €/MWh), τ is the discount rate and ε is the discount rate in
the energy sector. According to [25,26], τ is fixed to 1% and ε to 3%.
Table 9 reports the main items of initial investments for the installation of the wind farm.
In particular, the costs are evaluated considering the installation of 10 wind turbines, each one having
a rated power of 330 kW [27,28]. The unitary costs are expressed in function of the installed power.

Table 9. Initial costs of the wind farm.

Item Cost €/kW €
Wind turbine 1652 5,451,600
Grid connection 354 1,168,200
Constructions 236 778,800
Others 118 389,400
Total 2360 7,778,000

Similarly, Table 10 reports the main items of initial investments for the installation of the biomass
power plant. We consider the installation of eight ORC (Organic Rankine Cycle) units, each one having
a rated electrical output of 150 kW [11,29].

Table 10. Initial costs of the biomass power plant.

Item Cost €/kW €
ORC unit 2440 2,928,000
Grid connection 150 180,000
Constructions 270 324,000
Others 50 60,000
Total 2910 3,492,000

Table 11 reports the initial costs for the installation of a wave farm, composed of 20 DEIM points
absorber, each one having a rated power of 80 kW.