**8. Conclusions**

The main objective for this project was to design an energy system after analyzing different alternatives of renewable energy integration to reduce the current electricity cost to 52 p/kWh from August 2018 to 2019 and then reduce it to a minimum of 49 p/kWh from 2019 to 2020. One of the main requirements at the start of this project was to be able to obtain an annual load profile from the island itself, but after conducting research, we determined that this was not possible due to lack of available data. The annual load has been estimated as an hourly consumption profile for Sark Island, which directly influenced the results of this study by adding currently unknown uncertainty to the calculations. Because of this, the results can vary if real data is obtained and the assumed consumption profile is different. As an example, the load profile selected resembles the behavior of the UK mainland, with peak consumption in winter due to the similar average temperatures in the year, but it was also valid to assume a higher demand in the summer months due to an increase in tourists, just as the NAREC did in their report [19]. This report presents the case for electricity generation for the island, where a mix of solar and wind is used for the worst-case scenario, focusing on the estimated monthly energy consumed. The system sizing was undertaken by oversizing to reduce the risk of not enough energy being available. The method implemented in this research takes this into account and combines the current diesel generators to be able to reduce the uncertainty. By reducing the uncertainty, it has been possible to reduce the size of the solar system by 80% and both the wind turbine capacity and battery size by 50%.

After the data analysis, assumptions and the different sets of results for the installation cost, carbon emissions, and levelized cost of energy, the findings of this study can be summarized as follows.


• Case 3: The final case used a mix of solar and wind to have a more stable energy output during the day, when the peak on the load occurs with a 150 kW wind turbine and 150 kWp solar-PV system, producing 39% of the total annual load—75% comes from wind and 25% from the solar arrangement. This set up ends with an energy surplus of 6%. For this case in particular, the battery storage was eliminated in order to reduce the initial installation cost, and instead, the grid stabilization relies on the diesel generator of 600 KVA working constantly at a minimum base generation of 20% is nominal capacity and supplying the load when the renewable are not enough. This system has a minimum installation cost but elevated O&M and GHG emissions, with a reduction of only 20% on the emissions. Finally, this set up will have a higher cost of energy than the actual by 33%.

After summarizing all the results of this research and as previously explained, the results of this report depend vastly on the assumptions realized at the research and calculation stage. However, the case 2 renewable energy generation system is the most suitable in terms of the reduction of CO2 emissions and expected earnings from a lower LCOE. This study can be re-evaluated if actual data from the island is available, following the same methodology, in order to find the best solution for the island's current energy generation problem.

As Supplementary Material, a new load profile has been created where the load reaches a peak during the summer, in contrast to the previous assumption where the peak took place in the winter. This is based on the assumption that the large influx of visitors on the island will have an equivalent impact on the electricity consumption. The analysis was re-run to evaluate the results obtained for the new "worst case" scenario profile. This profile is based on the island of Cyprus that in similitude with Sark has a high tourism arrival during summer months thus a higher energy consumption.

#### **9. Further Studies and Suggestions**


**Supplementary Materials:** The following are available online at http://www.mdpi.com/1996-1073/12/24/4722/s1, Figure S1: UK-CY Load comparison, Figure S2: UK-CY Temperature comparison, Figure S3: Annual energy balance under di fferent levels of renewable energy production, Figure S4: Case 1: Scenario 5 instantaneous generation and load variation (top) and energy balance (bottom), Figure S5: Case 1: Scenario 6 instantaneous generation and load variation (top) and energy balance (bottom), Table S1: Case 1: Summary of all energy mix scenarios with estimated battery size comparison with the two different load profiles, Figure S6: Case 1 installation and O & M, Table S2: UK-CY: Case 6 performance evaluation and comparison under di fferent load profiles.

**Author Contributions:** Conceptualization, S.P. and T.M.; methodology, S.P., S.R. and T.M.; software, S.P., S.R. and T.M.; validation, S.P., S.R. and T.M.; formal analysis, S.P., S.R. and T.M.; investigation, S.P., S.R. and T.M.; resources, S.P., S.R. and T.M.; data curation, S.P., S.R. and T.M; writing—original draft preparation, E.J.G.; writing—review and editing, E.J.G.; visualization, E.J.G.; supervision, E.J.G.

**Funding:** This research received no external funding. **Conflicts of Interest:** The authors declare no conflict of interest.
