## 3 Case Study of the Port of Aviles
### Different Modeling Approaches
#### 3.2.2 HY4 RES Modeling  
In this analysis, the objective was to select out of all the energy sectors in the Port of Aviles the ones that would be more suitable to fit the energy prosumer based on one module of the hybridization system. Then, the chosen energy need profile covered four consumption elements in the port, namely the Embarcadero, the Rula Vieja, the Iglesia, and the Luz Roja (Figure 11), and this combination presented the following key parameters:  
* Peak load = 0.604 kW;
* Average hourly consumption = 0.161 kWh;
* Total annual consumption = 1410.3 kWh. The developed study used the following proposed hybrid scenarios:  
* Scenario 3--Solar, wind, and hydrokinetic energy and electric grid;
* Scenario 4--Solar, wind, and hydrokinetic energy and PAT (PHS), eventually requiring the electric grid to meet the defined load;
* Scenario 5--Solar, wind, and hydrokinetic energy and BESS (battery energy storage system), keeping in mind the primary renewable sources being solar + wind + hydrokinetic in all scenarios. * _Scenario 3--HY4 RES Modeling: Solar, Wind, and Hydrokinetic Energy and Grid_: In this scenario, the electric grid satisfied the energy needs that had not been satisfied by the primary renewables. The system was independent of the grid for \(\sim\)60% of the total annual hours and the energy needs were covered 72%. Nonetheless, the system exported more energy to the grid than it imported:
* Total annual exported renewables = 2681.2 kWh;
* Total annual imported renewables = 609.8 kWh. Despite the positive grid balance (more renewable exports than imports), most of the renewable energy produced was not consumed for the defined demand but was exported to the grid (Figure 12). Concerning the defined demand, the primary sources contributed 800.5 kWh (57%) to its satisfaction, while the grid ensured the fulfilment of the remaining needs, 609.8 kWh (43%). * _Scenario 4--HY4 RES Modeling: Solar, Wind, and Hydrokinetic Energy and PAT_: The goal of this configuration was to maximize the performance of the PAT (PHS) system. However, the site did not possess a significant height variation, and the module's scale was small. So, the production potential of the PAT subsystem was likely insufficient to meet all the defined energy demand without grid assistance. Figure 11: Total demand from the selected four sectors: Embarcadero, Rula Vieja, Iglesia, and Luz Roja. The following were the parameters for the PHS subsystem:  
* Pump-rated power (with an efficiency equal to the one in turbine mode) = 0.523 kW;
* Reservoir capacity = 10 m\({}^{3}\). In HY4 RES modeling, the pumped hydro storage (PHS) element was used as an important storage technique with upper and bottom water reservoirs. The energy was stored by retaining water in the higher-elevation reservoir and when needed, the water was released from the upper reservoir, flowing through a Pump-as-Turbine (PAT) driven by gravity to produce hydropower. During periods of surplus renewable energy production or lower demand, the excess energy was used to pump the water from the lower reservoir back to the upper one. The selected hybrid energy system allowed for flow variations using the upper tank inside the hybrid module and the sea channel in the port (with no necessary defined volume) as the lower one. HY4 RES privileged the operation of the pump and hydropower and the storage of water volume in the top reservoir, providing potential for additional energy production. Hence, HY4 RES used the following formulation: PHS operation depended on wind/solar energy, depending on whether they were available, expressed by Equation (18), where \(H_{need}^{i}\) is the required hydropower energy to satisfy the energy needs, in kWh; if the energy needed (\(E_{n}^{i}\)) was satisfied by the solar + wind energy produced and if there was a surplus of it, then the PHS was set to pump mode to use that same energy to pump water to the higher reservoir, expressed by Equation (19), where \(P_{s}^{i}\) is the available renewable energy to be used by the pumps, in kWh.