# A Novel Hybrid CSP-PV Power Plant Based on Brayton Supercritical CO\({}_{2}\) Thermal Machines
## 3 Results
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Component**} & **Heat Duty or Power** & **Mass Flow Rate** \\  & **[MW]** & **[kg/s]** \\ \hline Compressor (HPC) & 219 & 1025 \\ Turbine (HPT) & 122 & 1025 \\ Motor (MOT) & 97 & — \\ CO\({}_{2}\)/CO\({}_{2}\) (REC) & 279 & 1025/1025 \\ Thermal Oil/CO\({}_{2}\) (TOHX) & 128 & 582/1025 \\ CO\({}_{2}\)/Molten salts (MSHP) & 225 & 1025/798 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Energy balance at the design point of the heat pump (Figure 2). In the heat exchangers, the hot stream is designed in the first place. discharge of molten salts through the heat engine. This results in an overall production of 882 MWhe. In Figure 7a, the novel hybrid CSP-PV plant generates 50 MW of power during both radiation and non-radiation periods, summing up to 600 MWhe. While the electricity production is 282 MWhe lower in the novel design, the entire power injected into the grid comes from a synchronous generator, providing rotational inertia. Conversely, in the conventional plant, 582 MWhe come directly from the PV field. When curtailments occur, it is necessary to store all generated energy for subsequent injection into the grid. This scenario is analysed in Figure 6b for the conventional hybrid CSP-PV plant and in Figure 7b for the novel design. In Figure 6b, both the thermal output from the PTC field (128 MW) and the power converted from PV through electrical resistors (97 MW) are stored as thermal energy in molten salts during the radiation period. This stored thermal energy is then utilized through the conventional Rankine cycle (50/128 efficiency), resulting in a production of 527.34 MWhe (50 MW over 10.55 h). Regarding Figure 7b, the entire thermal output of the heat pump (225 MW) is stored within the molten salts during the radiation period. Subsequently, this stored thermal energy is converted into power (50 MW) through the S-CO2 power cycle during the discharge period (12 h), resulting in an injection of 600 MWhe into the grid. In this scenario, the electricity production originates from a synchronous generator in both plant configurations. However, the conventional plant experiences a loss of 72.66 MWhe due to the inability of the Rankine power cycle's efficiency penalty to be offset by any heat pump. Figure 6: Performance of conventional hybrid plant: (**a**) No storage of PV production; (**b**) PV production is fully stored. Tables 7-10 present the cost breakdown of different components of the proposed plant. By aggregating all on-site and direct costs and accounting for 25% of indirect costs, a total fixed capital investment of USD 416.5 M is obtained (equivalent to USD 8329/kWe). In order to facilitate a comparison of this investment with current technologies, Table 11 provides the specific costs of the main subsystems. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Component** & \begin{tabular}{c} **Heat Duty** \\ **[MW]** \\ \end{tabular} & \begin{tabular}{c} **Height** \\ **[m]** \\ \end{tabular} & \
\begin{tabular}{c} **Number of** \\ **Modules** \\ \end{tabular} &
\begin{tabular}{c} **On-Site** \\ **Cost [USD M2022]** \\ \end{tabular} \\ \hline REC & 279 & 3.92 & 96 & 39.0 \\ HTR & 226 & 2.67 & 22 & 21.7 \\ LTR & 79 & 4.25 & 32 & 17.5 \\ PC & 63 & 0.43 & 11 & 11.4 \\ TOHX & 128 & 0.40 & 8 & 10.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Size and costs of PCHE. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Component** & \begin{tabular}{c} **Heat Duty** \\ **[MW]** \\ \end{tabular} & \
\begin{tabular}{c} **Reference** \\ **PCHE** \\ \end{tabular} &
\begin{tabular}{c} **On-Site Cost** \\ **[USD M2022]** \\ \end{tabular} \\ \hline MSHP & 225 & REC & 30.0 \\ MSHE & 113 & HTR & 10.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Costs of H\({}^{2}\)X.  
Figure 7: Performance of novel hybrid plant: **(a)** half of solar radiation is stored; **(b)** the entire solar radiation is stored. Accurately determining the LCOE requires an annual simulation, taking into account the off-design response of the entire system.