Solar ponds using ammonium salts

Ammonium salts have good potential for use in salt gradient solar ponds. The environmental problems associated with NaCl are eliminated by incorporating the salt discharge from the solar pond into the fertilizer cycle of an agricultural system. Thermophysical and optical properties of several ammonium salts are sufficiently close to those of NaCl to suggest that the thermal efficiency of solar ponds using ammonium salts should be equivalent to that of a NaCl pond. Ammonia outgassing is minimal, and algae growth is curtailed by precipitating soluble phosphates. Because fertilizer is purchased for the agricultural system, the cost of salt for the solar pond is determined by the real interest for holding the fertilizer in inventory. These economics make feasible several desirable maintenance schedules for the solar pond.