A CSP-desalination system using a supercritical carbon dioxide Brayton cycle in Brazil

This paper intends to study the combined production of electricity and water using a solar tower CSP system. The system comprises a series of heliostats that reflect the incident solar radiation to falling particles in a central tower with thermal energy storage (TES). The energy is transferred to a recompression closed sCO2 Brayton cycle, and the rejected heat from the power cycle is used in a steam multiple-effect distillation desalination system. It was defined a fixed production of 10 MWe, and the required number of heliostats and energy from auxiliary and TES systems, as well as the production of freshwater, were determined. Five different locations in Brazil (four in the semiarid) were evaluated (with latitudes ranging from 4.69 to 32.02° S) and the results were compared, to determine the most viable location. It was observed that the best performance was achieved for the cities closest to the Equator, with lower variations of the incident solar radiation throughout the year. Icapuí (latitude 4.69° S) required the lowest number of heliostats (673), the lowest consumption of energy from the auxiliary source (43.3% of the thermal demand), and the highest production of freshwater. Rio Grande (latitude 32.02° S) required the highest consumption of energy from the auxiliary system (51.4% of the thermal demand) and the lowest production of freshwater, requiring the second largest number of heliostats. A levelized performance index was proposed to provide a graphical representation of the system performance. The highest LPI was found for Icapuí (22.72) and the lowest, for Rio Grande (19.44).