Cost benefit analysis of supercritical CO2 cycles in next-generation solar thermal power plants

Proposed future solar thermal power plant technologies commonly feature high-temperature supercritical CO2 (sCO2) power cycles due to predicted high thermal efficiencies and low capital costs. However, as the technology also poses significant challenges, a detailed techno-economic comparison is needed to assess potential benefits over state-of-the-art steam cycles. In this study, detailed thermodynamic models of six sCO2 cycles and a reference steam cycle as well as cost correlations for their main components were developed. The models were used for hourly simulations to derive the plants’ annual energy yields and levelized cost of electricity. Results show that the levelized cost of any sCO2 process is at least 9% higher than that of the reference system. Although there is considerable uncertainty in some of the components’ cost models, even lowering the costs of most sCO2-specific components by 50% did not lead to cost parity. This indicates that the development of next-generation solar thermal plants should include modern steam power cycles.