Solar Ponds - What Are They?

Abstract

Solar ponds can provide low cost solar energy collection as well as low temperature heat storage. Currently there are two types of solar ponds in an advanced state of development in the U.S. Each system uses a different collection and energy storage technique. The first system uses a large bag of water (a water bed in a greenhouse) which collects the solar energy during the day. After the sun's energy can no longer be collected the water is transferred to an insulated storage tank for use the next day. The second system uses a salt gradient within a water filled pond. The gradient prevents natural convective currents from dissipating the collected energy. The gradient pond has a solar heated layer within the pond. In this layer, a heat exchanger is installed to retrieve the collected solar energy. A solar pond of this design is providing heated pool water for a municipal pool in Miamisburg, Ohio.

This overview paper reviews the various designs of solar ponds and how they can be used to collect and store solar energy. The performance and cost data available will be presented and discussed.