Salinity gradient solar ponds hybrid systems for power generation and water desalination

Abstract

Solar energy is preferred over other energy sources because of its low cost, ease of collecting, and availability as a source of power, as well as its effectiveness in reducing pollution and water scarcity. Solar ponds are low-grade thermal energy systems that can also be used to absorb/store solar radiation. Extensive research/advances in solar pond performance have been sparked by the potential influence of various types of heat storage systems with heat extraction mechanisms. This article provides a comprehensive review based on the most recent accomplishments in the progress of solar pond technologies, salinity gradient solar ponds (SGSPs) for hybrid solar power generation, and water desalination systems. Applications of these technologies, including refrigeration and air-conditioning, and domestic and industrial process heating, have been explored and discussed. The literature review revealed that the low thermal efficiency of the solar ponds, which is considered the main challenge for a large-scale operation, could be overcome by considering stable salinity gradients, temperature gradients, and optimum thicknesses of zones. The novel advancements of hybrid systems and poly-generation energy systems for power generation and water desalination with a focus on the improvement of overall energy/exergy efficiency of salinity gradient solar ponds are the highlighting features of this review for imminent researchers. With the integration of salt gradient solar pond hybrid systems, a maximum lower convective zone (LCZ) temperature of 90 °C, more than 50 % energy/exergy efficiency, and power generation of up to 5 MW are reported in this review. For instance, an autonomous desalination unit exhibited about 54 % exergy efficiency and a production of about 2381 m3 (annually 73.3 %) of potable water.