Sensitivity analysis

A sensitivity analysis has been performed on two main parameters to understand how they affect the net present cost: the system lifetime and the hydrogen technologies investment cost. For the first case, three other possible system lifetimes are adopted in addition to 20 years as in the base scenario, that are 15, 25 and 30 years. Instead in the second case, only a possible future scenario is analyzed, when the hydrogen technologies development reaches a good situation with the reduction of the investment to about half of the present value; this could be considered as a 2030-scenario. In the following subchapters, the sensitivity analysis results are described in more detail.

6.3.1 System lifetime

A possible analysis on how the system lifetime affects the economic results can be done in this study. As initial hypothesis, an increase in the net present value is expected because of the higher operational and maintenance cost during the year but also for the higher number of replacements for some components. The main investment increase is probably due to the electrolyzer and fuel cell systems, because of the limited lifetime and the higher initial and

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replacement cost; also the dispenser for the hydrogen refueling station is replaced after 10 years, so increasing the lifetime more than 20 years, a second replacement is applied. Other replacements but of lower contribution in the NPV increase for a system lifetime higher than 20 years are the auxiliary battery and some of the CHP equipment, as dryer and gasifier.

Instead, a different reasoning must be done for the LCOE and LCOH evaluation; from one side, the NPV increase, so a possible increase can be expected for both the parameters, but also the electricity load satisfied and the hydrogen production for mobility increase, that can result a reduction for them. The behavior of the two parameters can be different, because the increase in NPV can be also due to only one of the two loads considered. In the following figure, the net present value variation is shown to better understand the system behavior; instead, in the next table the variation of LCOE and LCOH is explained.

Figure 55 NPV variation respect to system lifetime variation (sensitivity analysis)

Table 50 LCOE and LCOH variations respect to system lifetime variation (sensitivity analysis)

15 years 20 years 25 years 30 years LCOE [€/kWh] 1.23 1.28 0.98 0.92

LCOH [€/kg] 56.46 38.29 45.20 42.55

As expected, the NPV increase with the system lifetime for the higher replacements number but also the higher O&M costs; the variation is almost linear, and increasing or decreasing

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the system lifetime is expected to follow the same behavior. Considering an average lifetime of 6.7 and 4.8 years respectively for PEM electrolyzer and PEM fuel cell, the replacements are high affected by the system lifetime; for this reason, the NPVs of these systems are two of the main variations.

Instead, a stranger comportment is obtained for the LCOE and LCOH. For the first parameter, both increasing and decreasing the lifetime of the system a lower LCOE is obtained; this means that for a lower lifetime, the main contribution for the electricity part is the lower total NPV, but for higher lifetime instead, the lower value is due to the higher electricity load satisfied during the year. The opposite behavior instead is found for the LCOH, because for the 20 years scenario the minimum value is achieved; decreasing the lifetime, a higher LCOH is due mainly to the lower hydrogen mobility production although the lower total NPV. For higher lifetimes instead, initially an increase is evaluated because of the higher investment but for 30 years there is a reduction, mainly due to the increase in the mobility load satisfied during the years. So, the increase in NPV is mainly due to the mobility part.

6.3.2 Hydrogen technologies costs (future scenario)

Hydrogen-based energy production system at the moment are not developed as conventional technologies and this situation is also reflected in the global market with a higher investment cost. So, a future scenario with the half of the present costs is analyzed.

Obviously, considering a lower investment cost also the total net present value must be lower, but from the optimization algorithm the new set of components sizes must be examined to understand if there will be some variations respect to the base scenario. Both the base scenario and the CHP-optimized scenario are considered, and the variations are shown in the following figure.

As expected, the NPV is lower for both the scenarios considered. The LCOE and LCOH variation instead are explained in the next table; as an initial assumption, lower values for both the parameters are expected, but mainly for the LCOE because of fuel cell investment that affects only the electricity part.

Different behaviors are observed for the two scenarios under study; initially, for the completely CO2-free scenario (without CHP) the LCOE decrease but the LCOH increase in the future configuration. For the electricity part, this is mainly due to the reduction in fuel cell

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investment cost in concomitance with the reduction of electrolyzer cost, that in part affects the LCOE. But for the mobility part instead, an increase of the LCOH is cannot be explained;

part of the reduction in the electrolyzer NPV affects it, but this does not contribute for a LCOH reduction. The only possible reason is that the little sizes variations for electrolyzer and low pressure H2 storage tank, with an increase for both, affects only the mobility part.

The opposite comportment is achieved instead for the CHP-optimized scenarios, with an increase of the LCOE and a reduction in the LCOH. In this case, a little PV size reduction is obtained, so this probably affects mainly the LCOH value, instead the low increase of the hydrogen tank size is mainly due to the electricity part.

Figure 56 NPV variations with FC and EL investment variations (sensitivity analysis)

Table 51 LCOE and LCOH variations respect to FC and EL investment variations (sensitivity analysis)

No CHP CHP optimized

Actual Future Actual Future

LCOE [€/kWh] 1.28 0.87 0.29 0.34

LCOH [€/kg] 38.29 40.31 33.06 25.41

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