## 5 Conclusions  
This paper is focused on the assessment of the Levelised Costs of Electricity that should be expected if supercritical CO\({}_{2}\) power cycles were adopted in next generation Concentrated Solar Power plants for Solar Thermal Electricity generation. A simulation platform developed by the authors for the techno-economic analysis of Concentrated Solar Power plants has been integrated with the Solar Advisor Model to produce a larger simulation tool enabling the assessment of technical and non-technical plant characteristics to a level of detail not enabled by the latter software alone. Plants based on steam turbine technology and on sCO\({}_{2}\) cycles have been analysed under different financial/economic boundary conditions and for two different locations which can be regarded as above-average for CSP installations. In all cases, the net output of the plant is 50 MW and the Thermal Energy Storage system is sized to enable operation at full capacity for ten hours. In the most favourable cases, the Partial Cooling and Allam cycles provide an \(LCoE\) of 8.56 \(\circ\)/kWh and 8.33 \(\circ\)/kWh respectively, along with a Capacity Factor of around 59% and 62.5%. On the contrary, in the worst case, the \(LCoE\) of the Partial Cooling cycle increases to 11 \(\circ\)/kWh, with a \(CF\) slightly higher than 50%, while the values of the Allam cycle are 10.38 \(\circ\)/kWh and 55.4% respectively. When these figures of merit are compared with a reference plant based on a state-of-the-art steam Rankine cycle, the main finding is that both sCO\({}_{2}\) cycles have the potential to yield \(LCoEs\) comparable to those of the reference plant, or even lower. Taking into account the conservative approach employed throughout the present work, especially in terms of installation costs, this comes to confirm that sCO\({}_{2}\) power cycles are an interesting alternative to enhance the competitiveness of CSP-STE plants in the mid to long term, even if the drastic cost reductions claimed by some authors seem not to be so straightforward in the short term. In the longer term, mass deployment and a further refinement of the technology (technology/cost-wise) will very likely increase the economic gains of CSP-sCO\({}_{2}\) plants but, at the moment, this remains yet to be verified. In this regard, it is worth highlighting the groundbreaking concept proposed by the SCARABEUS project, funded by the European Commission and running from 2019 to 2023. In this project, CO\({}_{2}\) is doped with certain compounds to modify the critical properties of the resulting mixture, shifting the critical temperature to higher values and enabling the practical implementation of condensing sCO\({}_{2}\) cycles (for instance, the _Transcritical CO\({}_{2}\)_ cycle would be realisable even at very high ambient temperatures). Substituting these new CO\({}_{2}\) mixtures for pure CO\({}_{2}\) in the same layouts would, in turn, boost the efficiency of the resulting power plant, which translates into a smaller footprint of the solar field and also smaller size of the Thermal Energy Storage system. If these were eventually possible, as already suggested by the preliminary results in [3], the resulting power plant would easily reduce the LCoE reported in this paper by a large margin, possibly achieving the ambitious targets set forth by the SunShot programme. Conceptualization, D.S. and T. S.-L.; formal analysis, G.S.M. ; funding acquisition, D.S. ; investigation, F.C. ; methodology, F.C., D.S. and F.J. J.-E.; software, F.C., G.S.M. and F.J.J.-E.; supervision, T.S.-L.; validation, T.S.-L. and F.J.J.-E.; writing--original draft, F.C. ; writing--review and editing, D.S. and T.S.-L. All authors have read and agreed to the published version of the manuscript. The SCARABEUS project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement N \({}^{\circ}\)814985.