## 3 Results
### Economic Results  
To assess the feasibility of this study, the Levelized Cost of Additional Energy (_LCOAE_) and the payback period are calculated. For LCOAE, Equation (5) [29] is used with the values in Tables 5 and 6 adjusted to the year 2023 using the Chemical Engineering Plant Cost Index (CEPCI) [30]. The terms used in Equation (5) are \(CAPEX_{E}\): the total initial costs to build the hybrid part of the plant, \(\textit{OPEX}_{E}\): the fixed and variable operation costs of the plant in year \(t\), and \(E_{ann,t}\): the total energy yield from the hybridization in year t. The lifetime of both the CST and biomass components is taken as 25 years [20; 28], as in the literature. Moreover, the discount rate is chosen as the global interest rate index at 8% (The case study involves the setting of Denizli, Turkiye. Turkiye is having an episode of very high inflation since 2017 that would disturb the calculations. As all the calculations have been made in Dollar terms, the price level changes in the local settings have been partially reflected in the calculations. Thus, the globally listed interest rate is assumed and used in this study for economic calculations) [31]. The results are presented in Table 7 and the resulting LCOAE is 81.19 USD/MWh. \[LCOAE=\frac{CAPEX_{E}+\sum_{t=1}^{n}\frac{\textit{OPEX}_{E,t}}{(1+r)^{t}}}{ \sum_{t=1}^{n}\frac{E_{ann,t}}{(1+r)^{t}}} \tag{5}\] \begin{table}
\begin{tabular}{l l l l} \hline \hline
**System** & **Subsystem** & **Value** & **Unit** & **Source** \\ \hline \hline
**CST** & & & & \\ \hline
**Direct Costs** & & & & \\ \hline Site improvements & - & 15 & 2021 USD/m\({}^{2}\) & [32] \\ Solar field & - & 100 & 2021 USD/m\({}^{2}\) & [32] \\ HTF & Piping & 27.7715 & 2021 USD/m\({}^{2}\) & [32] \\  & Other & 10.2285 & 2021 USD/m\({}^{2}\) & [32] \\  & Fluid & 21 & 2021 USD/kW & [32] \\ Power Block (PB) & Turbine & 308.11 & 2021 USD/kW & [32] \\  & Other & 416.48 & 2021 USD/kW & [32] \\  & Balance of Plant & 97.34 & 2021 USD/kW & [32] \\ \hline \hline
**Indirect Costs** & & & & \\ \hline Site cost & - & 10,000 &
\begin{tabular}{l} 2021 \\ USD/acre \\ \end{tabular} & [33] \\ EPC and owner & - & 11\% & \% direct & [32] \\ Contingencies & - & 7\% & \% direct & [32] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Cost items in LCOAE calculation. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Parameters** & **Value** & **Unit** \\ \hline PTC Gross Aperture Area & 48,384 & m\({}^{2}\) \\ Power Block Capacity—Topping & 16,000 & kW \\ Power Block Capacity—CST Share & 10,000 & kW \\ Power Block Capacity Biomass Share—Topping Only & 10,000 & kW \\ Power Block Capacity Biomass Share—Topping + IPT & 14,372 & kW \\ Land Area & 98.84 & acre \\ Energy Capacity in 1 year & 20,000 & kW-yr \\ Energy Produced in 1 year & 131,708 & MWh \\ Biomass Fuel Consumed in 1 year (max) & 177,620 & tonnes \\ Biomass Thermal Capacity & 98,565 & kW\({}_{\text{th}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Necessary plant parameters for LCOAE calculation. Another important parameter is the payback period. Two separate values are calculated for the payback period to display the difference between a support incentive like YEKDEM [19] and the spot market [35]. Equation 6 is used for both scenarios with values in Table 8, which also contains the YEKDEM prices. The results are presented in Table 9 and are discussed in the Section 4. \[\textit{Payback Period}=\frac{CAPEX}{Annual\ Savings} \tag{6}\]  
Another important parameter is the payback period. Two separate values are calculated for the payback period to display the difference between a support incentive like YEKDEM [19] and the spot market [35]. Equation 6 is used for both scenarios with values in Table 8, which also contains the YEKDEM prices. The results are presented in Table 9 and are discussed in the Section 4. \[\textit{Payback Period}=\frac{CAPEX}{Annual\ Savings} \tag{7}\]