Volume 23, No.1, Spring 2005

Presto Fresh Water

A new technology could make use of excess heat and at the same time produce millions of gallons of fresh water from power plants. The novel idea originated with two professors at the University of Florida, James Klausner and Renwei Mei.

What the two academics saw was power plants using huge amounts water for cooling. Nearly 25 gallons of water are required to produce one kilowatt-hour of electricity. So it is not surprising that power plants consume 39 percent of the water used in the United States, making them second only to agriculture in water use. At the same time, fresh water is in high demand. Desalination is one answer, but this energy-intensive technology is not cost-effective. Most plants are located in the Middle East, particularly Saudi Arabia where energy is cheap and water scarce.

The solution proposed by the professors involves taking the water that is heated in the process of cooling the power plants and flowing it through a tower structure to force evaporation. Ultimately, the captured condensed water is salt-free. This new technique— diffusion-driven desalination or DDD—could produce 1.5 million gallons of fresh water by using what would have been wasted heat from a 100-megawatt power plant.

By building adjoining DDD plants, benefits would accrue to utility companies in the form of water to sell. Other industries could also put their wasted heat to use in the same manner. Refineries, pulp and paper plants, chemical and food-processing plants could produce fresh water for sale or even supply themselves with fresh water.

The University of Florida is working with Global Water Technologies of Golden, Colo., seeking to license the technology to other firms. They expect to have a large-scale demonstration project completed this year. An even larger commercial project is anticipated for 2006.

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