Solar Desalination Technology for Mid-Sized Applications

Secure sources of clean fresh water are essential to the welfare of communities throughout the world. To meet the growing demand for fresh water, communities are increasingly relying on large-scale desalination plants. Unfortunately, the source of energy to run these plants has almost always been fossil fuels. This project will develop a desalination technology that runs primarily on solar energy and can be economically competitive with fossil-fuel based systems. All thermal desalination processes first evaporate seawater and then condense the water vapor to produce freshwater. The new approach will employ a novel configuration for the evaporator and condenser, which will: (1) eliminate the need for large, costly vacuum shells; (2) convert the shells from expensive metallic heat exchangers to low-cost, corrosion-resistant plastic heat exchangers; and (3) retain high efficiency when a solar thermal energy source. In addition, a solar collector, designed specfically for desalination applications and much less expensive than conventional collectors, will be developed. Phase I will include: small scale bench-top experiments to both optimize and prove the performance of the novel evaporator/condenser; a proof-of-concept demonstration of a low-cost solar thermal collector, which is integrated into the desalination plant; a conceptual design for a full-scale plant; and an estimate for the cost of producing water from this plant. Commercial Applications and other Benefits as described by the awardee: In addition to desalination, the technology also should be applicable to the purification of brackish water ¿ which would be extremely important in the Southwest, where economic growth is straining water supplies and brackish water is frequently available. By efficiently producing mineral-free water, the novel desalination technology also could increase the use of high-efficiency evaporative coolers for HVAC applications