Environmental Innovations for Fossil Energy Applications; Development of Technologies to Reduce Freshwater Use and Consumption in Coal-Fired Power Plants

The steam cycle process used in coal-fired plants requires about 38 gallons of water per kilo-watt hour of electricity produced. The water is used mostly for steam cooling with a lesser quantity used for pollution control devices. This project will develop a novel, low-cost, vapor distillation technology that will enable municipal wastewater and non-traditional waters to be used as process water for coal power plants. An important feature the approach is the use of stack gas waste heat ¿ which otherwise would be discharged into the atmosphere ¿ for cleaning the contaminated water through a humidification/dehumidification process carried out at atmospheric pressure. Access to this heat stream is relatively easy and would not require a major redesign of the plant or a major shutdown for installation, making this technology economically attractive. Technical feasibility was demonstrated in Phase I. Phase II will involve measuring the operating parameters of the vapor distillation concept in a 1000 gallon per day pilot plant, producing a preliminary design for a representative plant, and using the design to estimate construction and operating costs. Commercial Applications and Other Benefits as described by the awardee: The technology should become suitable for retrofit to a large number of U.S. power plants. If 500 power plants (at an average size of 600 MW) used the technology, the volume of water recovered would be one billion gallons per day.