Salt-gradient Solar Ponds for Solar Energy Utilization

Salt-gradient solar ponds function as systems to collect and store solar energy. The upper zone of the pond is rendered non-convective by the salt gradient and serves as a partially transparent insulator, permitting some of the incident solar energy to penetrate to the bottom and heat the lower zone to a temperature as high as 95°C. A pond 3 m deep and 150 m2 in area is expected to provide all of the winter heat required by a house of the same area in Columbus, Ohio. Solar ponds occur in Nature. Research on artificial solar ponds was first begun in Israel in 1958 and some research has since been done in other countries. Recent results obtained by the author and collaborators indicate that solar ponds will be simple to operate and will provide low-temperature heat at a cost of perhaps $0.010 per kW-hr thermal. Experiments to obtain more definitive cost information are now in progress.