This report analyzes how thermoelectric plants use water and the strengths, limitations, and costs of available technologies for increasing water use efficiency (gal/MWh). The report will be of value to power company strategic planners, environmental managers, and generation managers as well as regulators, water resource managers, and environmentalists.
Population and economic growth increase use of fresh water resources. Demand for electricity also is increasing. Thermoelectric generation already accounts for approximately 40% of national freshwater withdrawals at a time when ecological concerns limit freshwater availability for population, power generation, industrial, and agricultural uses and considerable uncertainty exists about how future climate variability and change may alter water supplies. A consequence of all these factors is increasing pressure on the electric power industry to consume less water and use it more efficiently.
To provide an overview of the major uses of water for power plant operations and a basic introduction to water conservation options generally available today.
The project team began with a quantitative overview of water use by application and by type of plant—fossil and nuclear steam-electric plants, gas-fired turbine plants, and renewable plants. The body of their research analyzes alternative water conservation management options available today. These include
- in-plant recycling and reuse of water to minimize water intake and discharge;
- various dry technologies for cooling, scrubbing, and ash handling, as well as wet/dry hybrid technologies and the comparative costs;
- alternative sources of water for the future, including municipal wastewater, brackish ground water, and water produced during oil and gas operations; and
- basic economics of water including cost of acquisition, delivery, treatment, and discharge.
In an effort to synthesize key elements in the report for readers, the team provided six hypothetical case studies of different types of power plants operating under different conditions in the United States.
Plant type is the dominant factor in determining water requirements. In plants with water-cooled condensers, cooling will dominate the plants' water needs. Approaches to increasing water use efficiency or decreasing water use in power generation include dry/hybrid cooling; nontraditional water sources; recycle and reuse of water within plants; combined–cycle, photovoltaic, wind, and gas turbine generation; dry scrubbing; and dry ash handling. Relative advantages, limitations, and costs of different water conserving technologies are highly site dependent.
Growing societal demands on U.S. water resources will result in pressure on the electric power industry to increase its water use efficiency and reduce its total water use. The power industry is already engaged in conserving water on many fronts—developing dry cooling, dry scrubbing, and dry ash handling technologies; creating new and innovative recycling systems for treating and reusing water for various plant functions; and pioneering ways to make use of abundant and untapped supplies of municipal waste water and other nontraditional sources. Through scientific/technical research, there exist opportunities for the power industry to develop improved and less costly technologies and procedures for conserving water.