# Thermoeconomic Analysis of Concentrated Solar Power Plants Based on Supercritical Power Cycles
## 4 Conclusions  
This work focuses on the study of a STPP configuration that is included in the new generation of STPPs, aiming to reduce costs through improved performance by employing supercritical power cycles [2]. Specifically, this STPP is based on a central solar receiver refrigerated by a pressurised gas and coupled to a supercritical power cycle. Compared to more conventional configurations of the aforementioned scheme, this STPP presents two innovative elements. Firstly, the power cycle is a SCO\({}_{2}\) partial-cooling layout, which presents significant advantages compared to conventional recompression, such as lower investment due to the smaller recuperator volume, higher thermal efficiency, and higher temperature increment of the sCO\({}_{2}\) in the primary heat exchanger. This leads to a smaller volume of gas to be heated in the receiver, which directly reduces the receiver sizing and the solar field cost. Secondly, the STPP features a novel receiver design based on compact structures in a radial configuration. This design is particularly suitable for working with pressurised gas. The comparative analysis conducted in this study involves keeping a constant thermal power supplied by the solar receiver while varying its design through the number and dimensions of the absorber panels. The analysis demonstrates that there is an optimal configuration that balances two opposing effects: the increase in receiver thermal efficiency as the number of absorber panels increases, and the decrease in optical efficiency due to increased spillage as the receiver size is reduced. Although this optimum will depend on the specific working conditions chosen, it provides an idea of the range in which the solar thermal plant operates optimally, resulting in lower electricity generation costs. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{8}{c}{**Number of Converging Absorber Panels**} \\ \cline{2-10}  & **6** & **7** & **8** & **9** & **10** & **11** & **12** & **14** & **16** \\ \hline \multicolumn{10}{c}{Design parameters} \\ \hline Tower height (m) & 109 & 109 & 109 & 109 & 109 & 109 & 109 & 109 & 109 \\ Receiver absorber area (m\({}^{2}\)) & 718.123 & 621.922 & 549.965 & 494.547 & 450.917 & 414.842 & 384.996 & 333.777 & 292.227 \\ Number of heliostats & 1243 & 1245 & 1259 & 1269 & 1294 & 1339 & 1401 & 1566 & 1869 \\ \hline \multicolumn{10}{c}{Economic parameters} \\ \hline Tower cost (Mio. \$) & 10.281 & 10.281 & 10.281 & 10.281 & 10.281 & 10.281 & 10.281 & 10.281 & 10.281 \\ Receiver cost (Mio. \$) & 59.546 & 53.843 & 49.402 & 45.863 & 42.991 & 40.554 & 38.489 & 34.828 & 31.733 \\ Site improvements cost (Mio. \$) & 2.871 & 2.875 & 2.910 & 2.930 & 2.989 & 3.093 & 3.236 & 3.617 & 4.317 \\ Heliostat field cost (Mio. \$) & 26.021 & 26.063 & 26.356 & 26.560 & 27.089 & 28.031 & 29.329 & 32.783 & 39.126 \\ Contingency cost (Mio. \$) & 4.210 & 4.052 & 4.620 & 4.355 & 4.18 & 4.069 & 4.031 & 4.115 & 4.46 \\ Total direct cost (Mio. \$) & 102.929 & 97.114 & 93.569 & 89.989 & 87.530 & 86.028 & 85.366 & 85.624 & 89.917 \\ Land cost (Mio. \$) & 2.842 & 2.812 & 2.930 & 2.876 & 2.889 & 2.956 & 3.075 & 3.443 & 4.314 \\ Sales tax cost (Mio. \$) & 2.574 & 2.477 & 2.940 & 2.778 & 2.671 & 2.606 & 2.59 & 2.654 & 2.899 \\ Total indirect cost (Mio. \$) & 5.416 & 5.289 & 5.870 & 5.654 & 5.560 & 5.562 & 5.665 & 6.097 & 7.213 \\ \hline Total capital cost (Mio. \$) & 108.345 & 102.403 & 99.439 & 95.643 & 93.090 & 91.590 & 91.031 & 91.721 & 97.130 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Summary of the total capital cost of the solar subsystem of each solar thermal power plant, based on a partial-cooling sCO\({}_{2}\) cycle.