WASHINGTON, DC— As part of an expanding effort to address the critical link between energy and water, the U.S. Department of Energy (DOE) has selected seven projects aimed at reducing the amount of freshwater needed by coal-fired power plants.
This work, which represents a follow-on to an initial 2003 DOE solicitation directed at power plant and water issues, specifically focuses on three areas of research: non-traditional sources of water, advanced cooling technology, and advanced water recovery and reuse technology.
Under DOE’s Innovations for Existing Plants program, which is designed to enhance the environmental performance of existing coal-fired power plants, the Energy Department and its research partners will cost-share in a broad mix of projects with a total value of more than $5 million. The projects will be managed by the Office of Fossil Energy’s National Energy Technology Laboratory.
The nexus between energy and water has become a topic of increasing concern. In the United States, thermoelectric power plants account for daily withdrawals of about 136,000 million gallons of freshwater, second only to withdrawals for irrigation.
While most of the water withdrawn is returned to its source, issues about water availability and ecological and quality impacts continue to challenge the operation of existing power plants and the permitting of new power projects. In addition, power plants will increasingly compete for freshwater with other use sectors such as residential, commercial, agricultural, industrial, and in-stream use, not only in the arid West, but in many other regions of the country as well.
In response to these challenges to national energy and water sustainability and security, the combined expertise and experience of a team of academic and industrial partners will be brought to bear on the development of technologies and concepts to reduce the demand for freshwater by the thermoelectric generating sector. The selected projects are described below:
- Building on past studies demonstrating that mine water can reduce the capital cost of acquiring cooling water and improve cooling efficiency, the National Mine Land Reclamation Center at West Virginia University will develop a framework to assess the costs, as well as the technical, regulatory, and environmental benefits, of using mine water instead of freshwater to generate thermoelectric power. Researchers will conduct a field study at the proposed 300-megawatt Beech Hollow Power Plant in Champion, Pa., to identify mine water sources to supply 2,000 to 3,000 gallons of water per minute. (DOE share: $338,250; university cost share: $86,816; project duration: 24 months)
- Lehigh University will investigate the use of condensing heat exchangers to recover water from boiler flue gas. Researchers will conduct laboratory and pilot-scale experiments to determine the amount of acid vapors from the flue gas and condensation of water vapor that can be achieved in separate stages of the heat exchanger system. Additional benefits of cooling the flue gas are the simultaneous removal of sulfuric acid and an increase in power plant efficiency.
(DOE share: $558,952; university cost share: $141,581; project duration: 30 months)
- Marley Cooling Technologies, Inc., will determine the benefits of its patented Air2Air™ condensing technology as applied to a cooling tower by adding its new technology to an existing evaporative cooling tower at a coal-fired power plant to be selected. The company will study and quantify the amount of water recovery from the normal evaporation process and subsequently determine the performance and operating parameters of the condensing technology. The ultimate benefit to be explored will be the water savings potential of the condensing technology. (DOE share: $650,106; industry cost share: $162,527; project duration: 18 months)
- The Nalco Company plans to develop novel membrane separation and scale-inhibitor technologies to enable coal-fired power plants to economically use “impaired” water for cooling. Impaired water—water of inferior quality—holds promise for cooling, but the treatment costs and other inherent problems for power plants makes the current use of impaired water improbable. By applying membrane and scale-inhibitor technologies to the problem, Nalco plans to take a major step toward removing the barriers to the use of impaired water.
(DOE share: $897,505; industry cost share: $592,489; project duration: 36 months)
- The University of Pittsburgh will assess the potential of three different impaired waters—secondary treated municipal wastewater, passively treated coal-mine drainage, and ash pond effluent—as cooling waters for coal-based thermoelectric power plants. Researchers will also operate small pilot-scale cooling towers for side-by-side evaluation of impaired waters under different condition and will assess the feasibility and relative importance of the three impaired waters by examining their availability at 12 specific power plant locations. The ultimate goal is to provide alternative sources of water for cooling systems. (DOE share: $617,703; university cost share: $205,779; project duration: 36 months)
- The URS Group will demonstrate the use of regenerative heat exchange to reduce fresh water use in coal-fired power plants equipped with wet flue gas desulfurization (FGD) systems by minimizing evaporative water loss in the FGD systems. During the demonstration, the flue gas will be cooled enough to reduce the evaporation of water in the wet FGD system by about one half. Ultimately, the demonstration will estimate the nationwide reduction in freshwater over the next 15 years. Overall, the URS Group will provide an option to address an additional 82 gigawatts of FGD capacity expected to be installed by 2020. (DOE share: $573,116; industry cost share: $143,280; project duration: 21 months)
- Drexel University will develop technologies that reduce freshwater consumption from all coal-fired power plant water-intensive components, including cooling towers, scrubbers, coal dryers, and ash handlers. Drexel proposes to develop a scale-prevention technology and a novel filtration method to ultimately increase the cycles of concentration in power plant cooling towers, thus eliminating the need for make-up water. (DOE share: $899,756; university cost share: $231,436; project duration: 36 months)