3.5.4. Cost Results

Given the high fluctuation of fuel costs due to geopolitical variables, the highest price was taken. This affects the projection as at the beginning of this project the price of the *LH*<sup>2</sup> was three-times lower than the stipulated price. *CO*2, *NOx* and Noise costs were charged to the reference aircraft based on the methodology of Johanning and Scholz [72].

This new methodology includes the additional cost applied in the form of tax for pollution and noise at airports from 2000. The results for the benchmark mission are shown in Figure 13. These prices are reflected mainly in the reference aircraft. Pollution and noise charges represent 0.2% and 0.02%, respectively, of the total DOC.

The costs were divided into their respective categories, and the unit EUR/Seat-100 km represents the costs in Euros per seat per 100 km. These results indicate a total cost saving of approximately 19% on the total DOC only taking into consideration the prices for green hydrogen. On the design route, this implies a saving of 2 million euros per year per aircraft. However, hydrogen prices can have a significant impact on the cost of the mission depending on the type of hydrogen to be used, i.e., blue or gray hydrogen as can be seen in Figure 13. For example, using blue hydrogen produces a 25% savings in DOC and approximately 28% in the case of using gray hydrogen, actions that nevertheless would not nullify polluting emissions due to the way in which these fuels are obtained.

Additionally, although the variable that most influences operating costs in a positive way is fuel, in this study, a negative performance was observed in other variables, such as depreciation, interest, crew, maintenance and taxes, where there is a slight increase in prices.

#### *3.6. Turnaround Process*

As discussed in Section 2.4, the passengers are the critical path for the turnaround. Both refueling and baggage take less time, while the battery recharging takes the exact same time as the passengers. Specifically for the refueling, a total time of 9 min was achieved, while a maximum time of 21 s was required for actual hydrogen flow. Table 14 lists the total times for all considered turnaround segments.

**Figure 13.** Cost for design mission for HAIQU based on 1500 flights per year.

**Table 14.** Turnaround process times.

