Techno-economic assessment of a numbering-up approach for a 100 MW_e third generation sodium-salt CSP system

This work presents the design and techno-economic analysis of a 100 MW_e concentrated solar power (CSP) system using a supercritical CO₂ power block with 700 °C input temperature. Aiming to leverage the relatively higher efficiency of small heliostat fields and potential multi-build discounts, a numbering-up approach is examined, developing four alternative configurations (1×100, 2×50, 3×33, and 4×25 MW˙e), in which each module has its own dedicated tower, heliostat field, receiver, thermal storage and power block. A comprehensive techno-economic model is combined with detailed annual simulations to yield levelised cost of energy (LCOE) estimations and analyse the potential of system numbering-up for high-temperature next-generation CSP systems based on liquid heat transfer fluids (HTFs). The simulations are verified against the System Advisor Model with differences in the LCOE calculations within ±1.0%. Comparing the four systems shows that a 1×100 MW˙e system leads to an LCOE of 54.88 USD/MWh˙e, lower than for the numbered-up modules. However, the LCOE difference between configurations with one and two modules is moderate, with the 2×50 MW˙e configuration showing an LCOE of 55.99 USD/MWh˙e (+2%). Despite their higher annual conversion efficiencies, the 3×33 MW˙e and 4×25 MW˙e systems are more capital-intensive and escalate LCOE by 6.9 and 12.2%, respectively. With size-dependent power block efficiency, further LCOE escalation with numbered-up systems is observed, however, multi-build savings could potentially reverse this cost escalation and a 13.9–19.6% saving on the two-module system would allow them to break even.