DOE Selects 10 Projects to Conserve Freshwater at Coal-Fired Power Plants
August 5, 2008 // Published as a news service by IHS
The U.S. Department of Energy (DOE) announced the selection of 10 projects aimed at developing advanced technologies and concepts to minimize freshwater withdrawal and consumption by coal-based power systems.
By improving the environmental performance of coal, the projects will strengthen national energy security and help provide clean, affordable, abundant energy for future generations, said DOE.
Thermoelectric power plants are the second largest user of freshwater in the U.S., requiring significant volumes to cool and condense the low-pressure steam from the plant's electricity-generating turbines.
Only the agricultural sector, which uses large quantities of water for irrigation, withdraws more freshwater than thermoelectric power plants, said DOE.
The operation of existing thermoelectric power plants and the permitting of new plants are challenged by competing demands from other water-use sectors, increasingly stringent water-related environmental requirements and growing populations in water-constrained regions, which increases the need for electricity.
A DOE analysis projects that the consumption of freshwater by thermoelectric power stations will increase over the next 20 years as older plants using "once-through" cooling retire and are replaced by new plants with "closed-loop" cooling systems, which lose water through evaporation.
The DOE analysis shows that the demand for water by the power sector could further increase if regulations are enacted to reduce emissions of the greenhouse gas carbon dioxide (CO2). As much as 30-40% of a plant's electrical output can be required to operate a carbon-capture system - additional capacity is needed to make up for the lost output, which increases demands for cooling water and water for plant operations.
The DOE Office of Fossil Energy Innovations for Existing Plants (IEP) program maintains a portfolio of research projects to address these and other environmental challenges faced by the existing fleet of coal-fired power plants in the U.S. Specific to water, the program has established both near- and long-term technical and cost targets.
The near-term target is to have advanced technologies ready for commercial demonstration by 2015 that, when used alone or in combination, can reduce freshwater withdrawal and consumption by at least 50% for thermoelectric power plants equipped with wet recirculating cooling technology, at a levelized cost of less that $3.90 per 1,000 gallons of freshwater conserved.
The longer-term target is to have technologies ready for commercial demonstration by 2020 that, when used in combination, can reduce freshwater withdrawal and consumption at thermoelectric power plants by at least 70%, at a levelized cost of less than $2.60 per 1,000 gallons of freshwater conserved.
The Energy Policy Act of 2005 directs the DOE to address issues related to water use for energy production. In addition, Fiscal Year 2008 Omnibus Appropriations Bill language directs the IEP program to address the need for advanced energy-water technologies.
The 10 new projects, totaling approximately $9 million from DOE and $3 million in cost sharing from the recipients, will focus on three topic areas: advanced cooling technology, innovative water reuse and recovery and non-traditional sources of process and cooling water. The selected projects and these areas of interest are described below.
Advanced Cooling Technology
Research in this area is intended to develop technologies that improve performance and reduce costs associated with wet cooling, dry cooling and hybrid cooling technologies. Selected projects will conduct research into cost-effectively minimizing the amount of water withdrawn and consumed by power-plant cooling systems.
Selected projects include:
- Drexel University (Philadelphia, Pa.) - Researchers will develop a new scale-prevention technology by continuously precipitating and removing dissolved mineral ions in cooling water. Removal of the dissolved mineral ions would allow power plants to increase the number of times that the water could be recycled before it would be discharged, which would effectively reduce the amount of makeup water needed for the plant.
It is anticipated that the technology could double the cycles of concentration thereby reducing the plant's blowdown by approximately 25%. (DOE share: $1,004,174; recipient share: $254,000; duration: 36 months)
- Spx Cooling Technologies Inc. (Overland Park, Kan.) - Investigators will improve the efficiency of power plant air-cooled condensers (ACC) by developing wind guide technology for these air-cooled systems. Major drawbacks to the application of dry cooling have included efficiency variation, efficiency reduction and capital and operating costs of the ACC units.
Spx Cooling Technologies will work to reduce the efficiency variation in windy conditions by developing physical enhancements to the base ACC. The efficiency improvement for the cooling process will be measured by adding the new technology to an existing ACC cooling process at a selected coal-fired power plant. (DOE share: $751,817; recipient share: $187,954; duration: 28 months)
- Spx Cooling Technologies Inc. - Air2Air technology has the potential to reduce freshwater withdrawal and consumption by recovering 15-25% of water from cooling-tower evaporation. In this project, Spx Cooling Technologies will further develop Air2Air condensing technology, enabling it to become a cost-effective and viable water-savings technology.
Researchers will focus on solving issues of economy as they relate to superstructure volume, pack cost and costly ducting details. A more efficient heat transfer pack with watertight wet path seals will also be developed. (DOE share: $652,066; recipient share: $163,017; duration: 25 months)
Innovative Water Reuse and Recovery
Considering the great quantity of water withdrawn and consumed by power plants, any recovery or reuse of this water can significantly reduce the plant's water requirements. Selected projects in this research area will develop advanced technologies to reuse power-plant cooling water and associated waste heat and will investigate methods to recover water from power-plant flue gas.
Selected projects include:
- Applied Ecological Services Inc. (Brodhead, Wis.) - In this project, researchers will investigate the use of wetlands as a treatment method for power-plant water reuse and as tertiary treatment of wastewater treatment plant effluent prior to use in a power plant. Specific objectives include
- Conducting a literature review on the use of restored wetlands for water cooling and heat management by various industries, including power producers.
- Conducting conceptual design and technical evaluation and modeling of specific cooling strategies that employ wetlands.
- Designing a scale model followed by field testing of restored wetland cooling-effectiveness and benefits.
(DOE share: $914,472; recipient share: $233,578; duration: 36 months)
- Gas Technology Institute (Des Plaines, Ill.) - Investigators at the Gas Technology Institute will develop and test a membrane-based technology to recover water and energy from power-plant flue gas. The first of two stages will recover high-purity water and energy that can be used to replace plant boiler makeup water as well as improve plant efficiency.
The second stage will recover the larger portion of water that can be used for cooling tower makeup. Research will include membrane design and modeling, performance optimization and lab testing, design and fabrication of a pilot-scale unit, pilot-scale testing and design scale-up. (DOE share: $1,148,141; recipient share: $289,975; duration: 36 months)
- Lehigh University (Bethlehem, Pa.) - Lehigh University researchers will develop condensing heat-exchanger technology for coal-fired power plants for the recovery of water from flue gas.
In particular, researchers will expand the database on water and acid condensation characteristics by performing slip-stream tests at two different power plants, develop cost-effective solutions to reducing acid corrosion of heat-exchanger tubes, determine condensed flue gas water treatment needs and develop condensing heat-exchanger designs for full-scale applications.
The successful development of cost-effective, corrosion-resistant condensing heat-exchanger systems for use in coal-fired power plants will provide opportunities to recover water from boiler flue gas. (DOE share: $920,484; recipient share: $266,817; duration: 29 months)
Non-Traditional Sources of Process and Cooling Water
Opportunities exist for the utilization of lower-quality, non-traditional water sources. The projects in this interest area will evaluate and develop cost-effective approaches to using non-traditional sources of water to supplement or replace freshwater for cooling and other power-plant needs.
Selected projects include:
- Arthur Langhus Layne (Tulsa, Okla.) - To reduce high-quality freshwater withdrawal and consumption for power production, project researchers will create an Internet-based, Geographic Information Systems (GIS) catalog of non-traditional sources of cooling water for coal-fired power plants. Data will be developed to allow the economically beneficial use of oil and gas produced water, abandoned coal-mine water, industrial waste water and low-quality groundwater.
By pairing non-traditional water sources to power-plant water needs, the research will allow power plants that are affected by water shortages to continue to operate at full capacity without adversely affecting local communities or the environment. (DOE share: $451,385; recipient share: $177,250; duration: 36 months)
- University of Illinois Board of Trustees (Champaign, Ill.) - Investigators will evaluate the feasibility of reusing three types of non-traditional water sources for cooling or process water for coal-based power plants in the Illinois Basin:
- Produced water from CO2-enhanced oil recovery.
- Coalbed methane recovery.
- Active and abandoned underground coal mines.
Tasks will include evaluating quantity and quality of the produced water, investigating suitable treatment technologies and conducting a detailed economic and benefits analysis. The research will provide critical information for the use of these non-traditional water sources for power-plant makeup water, which would allow for increased use of non-traditional waters in the Illinois Basin and nationally. (DOE share: $830,031; recipient share: $353,027; duration: 36 months)
- Carnegie Mellon University (Pittsburgh, Pa.) - Carnegie Mellon University will provide engineering and economic data and analyses to determine optimal treatment approaches for use of wastewater treatment-plant effluent as cooling water. Investigators will evaluate the costs and benefits of implementing tertiary treatment of municipal wastewater prior to use in power plants versus chemical treatment at the power plant to manage cooling-water quality.
Research will include studying current use of wastewater treatment-plant effluent for power-plant makeup; conducting laboratory tests, followed by pilot-scale field tests, with wastewater treatment-plant effluent of different qualities; testing a variety of corrosion, scaling and biofouling control methods; and performing comparative life-cycle cost and benefit analyses. (DOE share: $740,551; recipient share: $246,554; duration: 36 months)
- General Electric Global Research (Niskayuna, N.Y.) - Researchers at General Electric (GE) Global Research will develop a new silica-removal technology that can be used in combination with other separation technologies to make non-traditional waters available for use in evaporative cooling towers in thermoelectric power plants. Research will include material selection and synthesis; material recycle and bench-top demonstration; and design engineering, scale-up and pilot demonstration.
Results are expected to allow for the economical use of many impaired waters that are currently too expensive to treat with current technology. (DOE share: $1,367,930; recipient share: $586,256; duration: 36 months)
Source: U.S. Department of Energy Office of Fossil Energy.