## 3 Results
#### 3.1.1 Power-Generation Sector  
Figure 4 exemplifies the operation of the decarbonised power-generation sector through the condition of full energy autonomy. The road transport demand is been included in order to show its impact in a latter stage. Power injection per technology and the operation of the energy storage system (both electricity and H\({}_{2}\)) are shown for two representative weeks. Left-side plots show a week with large WE resources whereas the right-side plot corresponds to limited WE resources.  
The remarkable PV generation, together with high wind resources, entail a large amount of RE production, as Figure 4a shows. This excess of RE is mostly employed to feed the electrolysers that generate the gas turbine fuel, as Figure 4c depicts. The remaining renewable power that can neither be injected nor stored (see Figure 4e) is computed as surplus RE energy. The 3 rd and 4 th days show curtailment levels that reach up to 1500 MW.  
Despite the large EES capacity considered in this scenario, a short intermittency of WE generation changes the system's operation considerably. In a first instance, the EES injects power until total depletion (see Figure 4c,e). Then, the H\({}_{2}\) storage level is significantly reduced, since turbines must operate to partially cover the grid demand and there are limited opportunities to switch on the electrolysers. This behaviour becomes critical for larger periods with limited or no WE resources, as right-side plots evince. The island energy system responds with backup power fuelled with H\({}_{2}\), depleting the gas reserves until relevant wind resources are available again. In addition, the PV power excess is mainly used to feed the electrolysers, limiting the available energy to be stored.  
A summary of the simulation outcome for an entire year is included in the first column of Table 6. The WE intermittency and the limited PV capacity factor implies a large operation of H\({}_{2}\) turbines, with 1665 h of annual working time and almost 1 TWhe of electricity generation. The simulation results suggest that 650 MW of capacity would be required, similar in size to the current conventional park. The H\({}_{2}\) provision (2.1 TWh) would be supplied with 1.1 GW of electrolysis, demanding 2.8 TWhe of electricity and 0.56 h\(\mathrm{m}^{3}\) of water. The estimated capacity factor exhibits the poor value of 2475 heq, which might put the economic viability into question.  
Despite the large storage capacity and the use of H\({}_{2}\) as an energy vector, the estimated amount of RE curtailed is 2.6 TWhe (27.3%). This behaviour, which causes inefficiencies and profitability losses, might discourage the implementation of RE and the entry of private investment capital.  
\begin{table}
\begin{tabular}{c c} \hline  & **Efficiency Values** \\ \hline Average H\({}_{2}\) turbine thermoelectric efficiency & 0.40 \\ Electolysis efficiency & 0.75 \\ ESS charging/discharging efficiency & 0.90 \\ \(\eta_{ICE_{P}}\) & 0.28 \\ \(\eta_{ICE_{D}}\) & 0.32 \\ \(\eta_{FV}\) & 0.86 \\ \(\eta_{Charging}\) & 0.90 \\ \(\eta_{trans}\) & 0.93 \\ \(\eta_{ICE_{HD}}\) & 0.39 \\ \(\eta_{FCEV}\) & 0.54 \\ \hline \end{tabular}
\end{table}
Table 5: Overall efficiency values applied to obtain the LDV electricity demand.