## 5 Results and Discussion
### Economic Analysis
#### 5.2.2 Cost Evaluation for Scenarios II and IV  
As with the previous cases, Table 14 presents the costs for the various components of the CSP plants, indicating the reference year for each value. In this table, P\({}_{\text{EH}}\) refers to the selected power for the electric heater and P\({}_{\text{COMP}}\) refers to the power of the centrifugal compressor. Both power values are expressed in MW\({}_{\text{e}}\). For the components in Scenario IV, it is important to note that, due to the novelty of this type of solution, some costs had to be estimated approximately. For instance,  
* The cost of the electric heater was based on the price of a standard molten salt heater [74]. * The heat exchanger cost was selected as a future target value for this type of component [75]. * For other equipment, such as the compressor, the cost is straightforwardly calculable based on the existing literature [76]. * For transformers and the electric heater in both scenarios, the costs were sourced from [2]. Using (14) to adjust prices to 2023, the final values for 2023 are represented in Table 15. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Equipment** & **Scenario I** & **Scenario III** & **Units** & **Variation** \\ \hline \multirow{4}{*}{A} & Heliostats & 73.3 & 73.3 & \(10^{6}\) USD & 0\% \\  & Receiver and tower & 31.9 & 32.3 & \(10^{6}\) USD & \(-1.2\%\) \\ \cline{1-1}  & Energy storage & 29.0 & 21.6 & \(10^{6}\) USD & 34.3\% \\ \cline{1-1}  & Power block/steam generator & 37.0 & 39.9 & \(10^{6}\) USD & \(-7.8\%\) \\ \hline B = 15\% of A & Installation of equipment & 25.7 & 25.1 & \(10^{6}\) USD & 2.4\% \\ C = 5\% of (A + B) & Engineering and procurement & 9.8 & 9.6 & \(10^{6}\) USD & 2.1\% \\ D = 10\% of (A + B + C) & Contingencies & 20.7 & 20.2 & \(10^{6}\) USD & 2.5\% \\ \hline E = A + B + C + D & Total construction cost & 227.4 & 222.0 & \(10^{6}\) USD & 2.4\% \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Total costs for Scenarios I and III. Figure 8 shows the LCOE values for different years during the 2016-2021 period. As observed, these values are higher than those reported for Scenarios I/III, despite the higher electricity production. Additionally, the more surplus electricity stored thermally from the grid, the higher the LCOE. These increases are attributed to the following:  
* The high cost of the electricity received, with no consideration given to scenarios where electricity might be subsidized (e.g., to balance the grid). * The high costs of the plant components, which result from the novelty of such systems. * The optimization of the plant for thermal energy production rather than cost minimization. To compare the cost of energy storage installation, the levelized cost of storage (LCOS) was calculated using (15). \[LCOS=\frac{\sum_{t=1}^{n}\frac{I+M_{\rm t}+C_{\rm t}}{(1+t)^{t}}}{\sum_{t=1}^{ n}\frac{E_{\rm t}}{(1+t)^{t}}} \tag{15}\]  
where \(M_{\rm t}\) is operating and maintenance costs in year t, based on [77]; \(C_{\rm t}\) is electricity consumption costs in year t, calculated using the average electricity price for each year [78]; R is the discount rate (5%); N is the system lifespan (25 years); and E\({}_{\rm t}\) is the energy produced solely with the Carnot battery, defined as the difference between energy produced with and without the Carnot battery, expressed in (11).