Techno-economic analysis of a solar tower power plant with an open air brayton cycle and a combined cycle - A simplified calculation method

Abstract

In this study, a simplified calculation method to evaluate the thermodynamic performance of two solar tower power plants of 50 MW is proposed. The systems consist in an open air Brayton cycle and a Brayton-Rankine combined cycle. The electricity produced, the average annual efficiency of the heliostats field-receiver system, the efficiency of the thermodynamic cycle and of the entire plant have been determined for both systems. The performances of the two plants have been compared to conventional plants using molten salts. The analysis shows that both systems have better performances than conventional solar tower plants using molten salts. The specific annual electrical energy per square meter of heliostat is higher than that obtained for the plant using molten salts, by 11.5% and 38.7% for the Brayton and the Brayton-Rankine combined cycle respectively. Moreover, an economic analysis has been performed. The results show that a reduction of the Levelized cost of Electricity (LCOE) can be achieved compared to the traditional molten salt plants, with savings of 15% and 13.6% for the Brayton and combined cycle respectively.