Behaviour of a salinity gradient solar pond during two years and the impact of zonal thickness variation on its performance

Abstract

The interest in solar energy has increased substantially as a consequence of greenhouse gas emissions that result from the combustion of fossil fuels in power generation processes. Solar energy is likely to be the energy of the future and solar ponds, in particular, salinity gradient solar ponds (SGSP), facilitate simple and cost-effective thermal energy collection and storage. In this study; the influence of varying the thicknesses of the zones present in a salinity gradient solar pond on the temperatures of the upper convective zone (UCZ) and the lower convective zone (LCZ) is investigated. The study finds that thickness variation of the zones within the pond has a considerable impact on the temperature of the LCZ while it has a small effect on the temperature of the UCZ. The optimal thicknesses of the UCZ and the non-convective zone (NCZ) have been found to be 0.2 and 2 m respectively. The results also show that the type of application plays a substantial role in determining the depth of the LCZ, and that temperature of this zone varies with the rate of heat extraction. A period of no heat extraction is required to allow the pond to warm up and the length of this period depends on the depth of the LCZ, the type of application coupled with the pond, and the rate of heat extraction. It was found that the SGSP could be deeper with less surface area, and still suitable for applications that require low-grade heat. These findings could form the basis of future studies regarding the performance and financial viability of the overall depth of SGSPs.