3 - The Solar Pond Concept

Abstract

The solar pond concept in its present form was initiated and developed in Israel more than 15 years ago. It consists of shallow ponds about one-meter deep with darkened bottoms, in which a hypersaline solution is overlaid by a lighter fresh water layer. A nonconvecting situation is, thus, created and after a relatively long starting time, temperatures approaching 100°C can be achieved in the dense accumulating layer. Under such conditions, and providing that the hot water can be pumped out at a usable flow rate without disturbance of the interface between the dense and the light layers, it is possible to run a thermodynamic cycle using as the cold source any superficial water that may exist in the direct vicinity of the solar ponds. An efficiency of the solar pond as solar energy collector of over 20 percent can be achieved, approximately 4 percent of the incident energy being possibly converted into electricity through the thermal Rankine cycle. Each square meter of pond produces a peak net mechanical power of about 5 to 10 watts.