Monday, December 10, 2007

Power Plant Carbon Capture Will Vastly Increase Water Use

Dec 6: The U.S. Department of Energy Office of Fossil Energy's National Energy Technology Laboratory (NETL) has released a 2007 update to its groundbreaking study, Estimating Freshwater Needs to Meet Future Thermoelectric Generation Requirements. The updated analysis increases understanding of regional and national water needs and usage in the power industry, and provides input for research and development aimed at water-use reduction.

It is important to understand the difference in the terminology -- withdrawal v. consumption. The water required for thermoelectric plants is "withdrawn" primarily from large volume sources, such as lakes, rivers, oceans, and underground aquifers. While both freshwater (approximately 70%) and saline water (approximately 30%) are currently used for thermoelectric generation, the report focuses on freshwater because freshwater sources are becoming increasingly strained. Water "consumption" is used to describe the loss of that water, typically through evaporation into the air.

New in this year's report is a response to heightened concerns over atmospheric carbon dioxide. The report examines the possibility that future policies to combat climate change may result in the addition of carbon capture technologies to many coal-fired power plants by 2030. Since these technologies require additional water, the 2007 report includes case study scenarios that predict how much water may be needed by power plants when carbon capture technology is installed.

NETL notes that water has become a pivotal issue in the Nation since economic development hinges on the availability of freshwater. Public water systems, agriculture, power generation, and other industries all compete for limited regional water supplies. Although the power industry is only responsible for around three percent of the freshwater "consumed" in the United States, it accounts for nearly 40 percent of "withdrawals." Recently, construction of new power plants had to be shelved because water-use permits could not be obtained, and insufficient supplies of water due to extended drought and population growth have resulted in a reduction in plant output in several regions of the country.

The new analysis examines five separate future cases using NETL's Water Use Projections Model and projections for regional electricity demand and capacity from the Energy Information Administration's Annual Energy Outlook 2007. Like the 2006 report, the new report predicts freshwater withdrawal and consumption by thermoelectric plants regionally and nationally, by decade, through 2030. Four of the five cases presented in the 2007 report predict that, on a national basis, water withdrawals by the power industry will decrease. On average, water withdrawals by thermoelectric plants are projected to decline more than 3.5 percent. However, water consumption by thermoelectric plants is predicted to grow. By 2030, the average expected increase is 35.7 percent.

On a regional basis, water withdrawal projections for thermoelectric plants range from a 42 percent increase in the Northwest, to a 24 percent decline in the Rocky Mountain and southwest desert region. Freshwater consumption will increase in all regions, showing the largest gains in areas where the population is expected to increase the most - New York: 396 percent, California: 274 percent, and Florida: 250 percent.

According to the report, when carbon capture technologies are added to coal-fired power plants, water withdrawal nationally is projected to increase from 4.1 to 6.0 billion gallons per day, with an average projected increase of water withdrawal of seven percent. Water consumption is expected to rise from 2.2 to 4.3 billion gallons per day. The average increase of water consumption from all cases with carbon capture is 90 percent.

NETL is working to reduce water usage by fossil-fuel-fired power plants through their Innovations for Existing Plants program. The program's goals are to enhance the efficiency and environmental performance of existing coal-fired power plants and to apply novel concepts to advanced power systems. NETL recently joined with Sandia National Laboratories through a memorandum of understanding to advance research, development, demonstration, and, ultimately, the commercialization of technologies to reduce freshwater usage related to thermoelectric power production while minimizing its impact on water quality.

The report indicates, "At the nexus of water and energy lies a wide variety of societal issues, policy and regulatory debate, environmental questions, technological challenges, and economic concerns. Water is emerging as a significant factor in economic development activities. Planning efforts must consider the availability and quality of water resources in a given locality or region to ensure that supplies are available to accommodate existing and future water consumers over the long term. Failure to do so can result in stunted growth, economic flight, inequitable development, and even open conflict. In order for the power industry to be ecologically responsible, technologically ready, and economically stable, advanced research is imperative. Energy-water issues have become increasingly visible in recent years, with a variety of concerns on the mind of industry, regulators, Congress, DOE, and the general public... current trends indicate that demands on the nation’s supplies are growing while the nation’s capacity to store surface-water is increasingly more limited and ground-water is being depleted. Water availability issues are intensified by the fact that population increases are occurring in water-stressed areas..."

Access a release from NETL (click here). Access the 107-page updated report (click here). Access the NETL website on Water-Energy Interface for Power Plant Water Management (click here). [*Energy, *Water, *Climate]