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 CO 2 (sCO 2 ) 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 sCO 2 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 sCO 2 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 sCO 2 -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. • CSP plants with sCO 2 cycles have a higher levelized cost than those with steam cycles. • Costs of sCO 2 main components need to be lowered dramatically to reach cost parity • Simple, low-efficiency sCO 2 cycle are as cost effective as high-performance ones. • Off-design performance of cycles has low impact on annual yield.