Solar pond

Abstract

Use of shallow pools of liquid to collect low-temperature solar generated thermal energy on a large scale for commercial use becomes economically feasible when use is made of efficient means to keep the liquid in the pond clean, prevent evaporation, prevent air convection and prevent convective circulation of the liquid. Narrow elongated trenches, grouped together over a wide area, can be formed by bulldozer type equipment. Each trench is lined with a heat-absorbing black liner. The liquid in the bottom of each trench, used to absorb the solar energy, may be a brine solution or plain water, depending on the means used to remove the thermal energy from the pond. The heat-absorbing liquid is kept separate from the thermal energy removing fluid by means such as clear polyethylene material. The covering for the pond may be a fluid or solid. If the covering is a fluid, fire fighting foam, continuously generated, or siloons are used to keep the surface covering clean and insulated. If the thermal energy removing fluid is a gas, a fluid insulation layer contained in a flat polyethylene tubing is used to cover the pond. The side of the tube directed towards the sun is treated to block out ultraviolet radiation and trap in infrared radiation.