A thermo-economic methodology to select sCO2 power cycles for CSP applications. (March 2020)

• Record Type: Journal Article
• Authors: Crespi, Francesco; Sánchez, David; Rodríguez, José M.; Gavagnin, Giacomo
• Is Part Of: Renewable energy. Volume 147(2020)Part 3
• Page Start: 2905
• Page End: 2912
• Publication Date: 2020-03
• Subjects: sCO2 power cycle -- Thermo-economic analysis -- CSP power plant -- Thermal energy storage -- sCO2 power plant cost estimation; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2018.08.023
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: The interest in Supercritical Carbon Dioxide (sCO2 ) power cycles has grown exponentially in the last decade, thanks to distinctive features like the possibility to achieve high thermal efficiencies at intermediate temperature, small footprint and adaptability to a wide variety of energy sources. In the present work, the potential of this technology is studied for Concentrated Solar Power applications, in particular Solar Tower systems with Thermal Energy Storage. Further to a previous thorough sensitivity analysis of twelve sCO2 cycles assessing the impact of turbine inlet temperature and pressure ratio on thermal efficiency, specific work, solar share and temperature rise across the solar receiver, the present paper investigates the features of two of these cycles in more detail. The most important conclusions of this section are that: a) the peak values of these thermodynamic figures of merit are obtained at different pressure ratios; b) specific work and temperature rise across the receiver seem to follow parallel trends whilst this is not the case for thermal efficiency; c) for a given turbine inlet temperature, higher pressure ratios increase the temperature rise across the receiver strongly, but the effect on thermal efficiency is uncertain as this can either increase or decrease, depending on the cycle considered. A deeper analysis of thermal efficiency and receiver temperature rise is therefore mandatory, given that these parameters have a very strong effect on the capital cost of CSP power plants. On one hand, a higher thermal efficiency implies a smaller solar field, the largest contributor to the plant capital cost; on the other, the temperature rise across the receiver is inversely proportional to the size of the thermal energy storage systems, as it is also the case for state of the art steam turbine based CSP plants. In order to quantify these trends, an economic analysis is developed using an in-house code and the open-source software System Advisor Model to evaluate the trade-offs between these two effects. As a result, the Overnight Capital Cost is estimated at some 5000 $/kW, with the individual contributions of solar field, thermal energy storage and power block being given in the paper. Highlights: The capital cost of sCO2 cycles in CSP applications is in the order of 5000 $/kW. The cost of the TES system is dominated by the corresponding temperature rise. The cost of the solar field is dominated by thermal efficiency of the power block. The cost of the power block is dominated by cycle layout (number of major equipment). High pressure and moderate temperature at turbine inlet yield the optimum design.