**3. Results and Discussion**

Al-Tafilah has a hydropower potential of 1 MW and a high potential of solar and wind resources that can achieve both economic and technical feasibilities. The RES sizing in this study was made based on maximizing the RES fraction and constraining the *LCOE* to the electricity purchase tariff in Al-Tafilah. This will maximize the environmental benefits of the system by meeting the highest demand possible, at the same time guaranteeing the economic feasibility of the system. The technical and economic parameters of the optimal sized PV/wind-hydro without ESS are shown in Table 3. Without an energy storage system, the tri-hybrid system comprises a 29.4 MW PV system and a 56 MW wind system. This system can supply the demand with a RES fraction equal to 71.5%, as seen in Table 3. In the case where no constraints were forced on the *LCOE*, the RES fraction reached a value of 87.9%; however, the system was very large and not feasible, hence, unrealistic for consideration.



Figure 3 shows the demand-met energy profile of the hybrid system components and how their summation compares with the demand profile. It is clearly seen from the superposition of the demand met by the system components that these RES can work synergistically as a hybrid system, as the hybridization mode could achieve higher RES fractions. However, although the amount of energy generated is enough, the profiles of the energy generation and energy demand do not match; a result of the fluctuation of the solar and wind resources and the limited hydropower capacity of the system. Consequently, the system is not capable of meeting the demand at 100%. This is seen in Figure 4, where the mismatch is represented by the deficit portion of the bar chart. Figure 4 shows that although the quantity of energy can be more than enough, the mismatch between the supply and demand profiles could still cause energy deficiency. Therefore, when a RES is to be assessed, not only energy quantity should be taken into account, but rather the time it is needed in as well. Since 100% could not be reached solely by the RES, an ESS must be integrated into the system to supply the deficit.

**Figure 3.** Demand met by the renewable energy system (RES) components without ESS (levelized cost 4 of electricity (LCOE) of 0.12 \$/kWh).

To ensure Al-Tafilah could base its decentralized grid on the hybrid RES proposed, 100% of their demand must be met and matched. Therefore, an ESS that can supply the deficit must be integrated. The technical and economic parameters of the optimal sized PV/wind-hydro with ESS are shown in Table 4. The table examines two scenarios for the ESS-integrated system; a constrained and unconstrained LCOE. In the first scenario, the LCCOE was again fixed to the electricity purchase tariff at Al-Tafilah. Results showed that the system would comprise of 75.4 MW PV system and 28 MW wind system. It worth noting that the size of the PV system is larger than in the case where no ESS was integrated, while the size of the wind system decreased. The size increase could be attributed to the utilization of more energy to supply the storage system as well as the demand in the time when

solar energy is available. The result is a larger system, but with the great advantage of meeting the demand at 98.8%, RES fraction compared to only 71.5% previous value. If RES size was optimized to maximize the RES without any constraints on the LCOE, the system could meet 99.9% of the demand, with an acceptable LCOE of 0.165 \$/kWh compared with the current value of 0.12 \$/kWh. It is worth mentioning that the presented calculation of the LCOE was based on current prices of the RES technologies, which means these values will be less in the future as the prices of these technologies are expected to drop significantly in the next decades [53]. Figure 5 shows the demand-met energy profile of the hybrid system components when integrated with an ESS, and how their summation compares with the demand profile. The difference between this and Figure 3 resembles the power of the integration of the ESS in solving the mismatch problem. It is apparent in the figure that the demandmet and the actual demand curves coincide almost all the time. This is further clarified by Figure 6, with a significant reduction in the deficit portion when compared to Figure 4 that had no ESS backup. As explained earlier, there is still a 1% deficit due to the constraint forced on the LCOE. However, as this constraint is removed, Figure 7 shows that the demand and demand-met profiles coincide at all times, and no deficit portion is seen, which is further confirmed in Figure 8; i.e., the demand was met at 100%, but with a slightly higher LCOE compared to the current value.

**Figure 5.** Demand met by the RES components with ESS (LCOE of 0.12 \$/kWh).

**Figure 6.** Monthly energy generation by the RES components with ESS (LCOE of 0.12 \$/kWh).

**Figure 7.** Demand met by the RES components with ESS (LCOE of 0.165 \$/kWh).

**Table 4.** Technical and economic performance parameters of the PV/wind-hydro system with ESS.


**Figure 8.** Monthly energy generation by the RES components with ESS (LCOE of 0.165 \$/kWh).

The RES system with an ESS not only supply Al-Tafilah with decentralized electricity and help Jordan take a step further towards reducing energy-import dependency, but it also comes with economic and environmental benefits. In Jordan, power plants operated on combined cycles and fired with natural gas are used to supply part of the demand. When the proposed system provides the energy demand, the annual saving of fuel from a typical Jordanian plant, for example, the Al-Qatrana power plant, is equal to 20,365 tons-saved, which is equivalent to a reduction of 47,160 MtCO2 [3,54]. The fuel-saving and reduction in CO2 calculations were based on a previously developed code for the simulation of the power plant presented in those latter references, where detailed analysis of fuel consumption and CO2 emission calculations for the power plant can be found. Based on estimations by the United States Environmental Protection Agency, this CO2 reduction is equivalent to the carbon sequestered annually by US forest spreading an area of 61,589 acres. Therefore, the presented system also progresses Jordan's adherence to the greenhouse gas limit set by the Paris agreement. For a developing country like Jordan, a transition towards 100% is crucial, as a study by Mathiesen et al. [55] associated such transition with large earnings on export potential, creating jobs, and economic growth. So, this work, which demonstrated a step further towards a 100% renewable energy grid, will support a more robust economy, at the same time, a greener Jordan.

The fluctuations in the renewable energy resources (solar and wind resources), as well as the variation in the electrical demand, significantly affect the performance of RESs where the amount of variations depends on the RES configurations and the existence of ESS, as shown in Figure 9. It can be depicted from Figure 9 that the RES fraction of the hybrid PV/wind/hydro system without ESS is the most sensitive one to the variation in the resources and the electrical demand, which is expected because the ESS acts as a backup system to cover the deficit caused by the drop in the resources or the increase in the demand. Moreover, it can be seen that the increase in the resources and the decrease in the demand do not change the RES fraction of the hybrid system with ESS (specifically for the unconstraint scenario) since they reached almost 100% RES fraction.

**Figure 9.** The sensitivity of the RES fraction to the variations in the: (**a**) Solar and wind resources and (**b**) demand.

RES fraction Likewise, the LCOE of the system is sensitive to the variations in the renewable energy resources and the demand and also to the variations in the RES's costs (capital and maintain ace costs) as well as the annual discount rate where the largest variations in the LCOE is caused by the change in the resources and demand as shown in Figure 10 since the amount of energy met by the RES is controlling the LCOE which is in return affected by the change in the resources and the demand. It can be depicted from Figure 10c that all the LCOE of the hybrid system configurations have almost the same sensitivity to the variation in the RES costs. At the same time, it can be seen in Figure 10d that the LCOE of the system without ESS is less sensitive to the variation in the annual discount rate, unlike the systems with ESS.

**Figure 10.** The sensitivity of the LCOE to the variations in the: (**a**) Solar and wind resources, (**b**) demand, (**c**) RES costs, and (**d**) annual discount rate.

#### **4. Conclusions**

Many developing countries across the globe rely heavily on imported sources to cover their energy needs. As such, the development of a reliable yet cost-efficient means of energy production is vital for advancing the movement toward sustainable societies and fastening the economic growth in the desired country. Jordan, with no exception, relies on imported oil from neighboring countries to cover their domestic demand. Additionally, the lack of services and poor electrification of rural areas in the kingdom worsens the poverty problem. In this work, Al-Tafilah of Jordan was presented as a case study, and the technical, economic, and environmental benefits of a decentralized renewable energy system that can supply and match 100% of the city energy demand were investigated. Other rural cities in Jordan have higher RES potential; therefore, this study can be expanded to other parts of Jordan. A tri-hybrid system of wind, solar, and hydropower, and an energy storage system were modeled and optimized to maximize the matching between the energy demand and production profiles. Three main scenarios were considered, first a tri-hybrid RES without an energy storage system, with a constraint

on LCOE (a maximum of LCOE equal to the electricity purchase tariff was set). The second and third scenarios were investigations of the RES system integrated with an ESS, with and without constraints on the LCOE. Results showed that without an ESS, the hybrid system could only reach up to 71.5% RES fraction. However, the techno-economic analysis of the PV/wind-hydropower system with an ESS showed that the optimal system in Al-Tafilah comprising a 28 MW wind turbine, 75.4 MW PV, 1 MW hydropower, and a 259 MWh energy storage facility could achieve a 99% RES fraction. It offers an attractive LCOE of 0.12 \$/kWh (equal to the purchase tariff) and a payback period of 9 years. Results also indicated that with the installation of this system, an equivalent of 47,160 MtCO2 emissions could be avoided yearly, which demonstrates the environmental benefits of the proposed work. Therefore, these finding are essential not only for future renewable energy planning in the country and improving its economy but also for contributing to the ongoing force against climate change. When the constraint on the LCOE was removed, the RES fraction achieved was equal to 100%, with a slightly higher LCOE of 0.165 \$/kWh. Since the prices of RES technologies are expected to drop dramatically in the next decades, the last scenario can also be adopted as the LCOE drops significantly with the RES price reduction. Finally, sensitivity analysis showed that the RES fraction of the hybrid PV/wind/hydro system without ESS is the most sensitive configuration to the variation in the resources and electrical demand. In contrast, the LCOE of the three configurations showed the largest sensitivity to the variation in the resources and demand compared to its sensitivity to the RES costs and annual discount rate variations.

**Author Contributions:** Conceptualization, L.A.-G., A.D.A. and M.A.; methodology, L.A.-G.; software, L.A.-G.; formal analysis, L.A.-G. and A.D.A.; investigation, L.A.-G., A.D.A. and A.M.A.; data curation, L.A.-G. and A.D.A.; writing—Original draft preparation, L.A.-G., A.D.A., A.M.A. and M.A.; writing—Review and editing, L.A.-G., A.D.A., M.A. and N.K.A.; supervision, O.T., M.F. and N.K.A.; project administration, O.T., M.F. and N.K.A.; funding acquisition, N.K.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded internally by the Institute of Research for Technology Development, University of Kentucky.

**Acknowledgments:** The authors would like to thank Prof. Derek Baker from Middle East Technical University for providing the TMY data of Al-Tafilah.

**Conflicts of Interest:** The authors declare no conflict of interest.
