New comprehensive investigation on the feasibility of the gel solar pond, and a comparison with the salinity gradient solar pond

Abstract

Solar energy is increasingly being exploited to supply energy for many purposes. This paper explores the feasibility of gel solar ponds as a source of renewables, using theoretical evaluation. This could be of critical future utilization in areas such as desalination, where the gel solar pond could in effect be a means to deliver fresh water in the Middle East and other regions where water scarcity is predicted to become an increasingly critical issue to resolve. This study explores all aspects of the gel solar pond’s functioning, including optimal thicknesses for its different layers, and explores its strengths and weaknesses. In this study; temperature profiles in the upper convective zone (UCZ) and lower convective zone (LCZ) of a gel pond are investigated. The impact of the thickness of the pond’s layers on the temperatures of these zones was also investigated. The cost of the gel pond was calculated and compared with that of the salinity gradient solar pond (SGSP) for a particular application, the multi-effect desalination (MED), which is frequently used to desalinate sea water. The results showed that the gel pond could supply thermal energy to applications requiring low-grade temperatures, and that temperatures in the LCZ of the gel pond could reach values similar to those achieved in the SGSP. Varying the thicknesses of the gel layer and the LCZ affects the temperature of the storage zone. The optimal thickness of the upper water layer and the gel layer was found to be 0.05 and 0.9 m respectively, while the optimal thickness of the storage zone depends on the particular application for which the pond is being used in each case. The results also show that a gel pond normally costs more than a SGSP. This study illustrates that gel solar ponds can offer solutions to some of the challenges posed by the SGSP; however, difficulties relating to cost and labour decrease their potential exploitation. Gel ponds can be seen as a viable alternative to SGSPs only if cheap and environmentally friendly polymers are used to form the gel layer.