Comparative exergoeconomic evaluation of integrated solar combined-cycle (ISCC) configurations

Abstract

This paper provides an exergy, economic, and exergoeconomic comparative analysis for the three most promising solar thermal technologies of integrated solar combined-cycle systems: direct steam generation linear Fresnel collectors, solar power tower, and oil parabolic trough collectors. The exergetic analysis shows that configurations using Fresnel collectors result in the highest exergetic efficiencies (44.1%), while the configuration using a solar tower leads to the lowest efficiency of 33.2%. Integrating the solar field into the high-pressure part results in higher efficiencies for day operation. However, this limits the steam cycle to benefit from higher pressure levels, especially during night operation, as the cycle has to operate on the same design pressure level to avoid possible part-load losses. Findings of the economic analysis show that sharing the same power block of the combined-cycle plant results in a significantly lower incremental specific investment cost for concentrated solar power (2545 $/kW) that helps new installations at moderate investments, leading to steeper learning curves of the technology. Configurations using solar collectors with direct steam generation produce electricity at the lowest price of 36.75 $/MWh. The configuration using oil parabolic trough produces electricity at the highest price (38.62 $/MWh).