Tuesday, November 1, 2011

Impacts Of Power Plants On Great Lakes Water Resources

Nov 1: Approximately 90 percent of the electrical power in the basin is produced by thermoelectric plants, which use 26 billion gallons of water a day for cooling. A recently completed research project by the Great Lakes Commission (GLC), as part of the Commission's Great Lakes Energy-Water Nexus (GLEW) Initiative, sponsored by the Great Lakes Protection Fund, examined how water withdrawal or consumption associated with power production could impact the health of the Great Lakes basin's rivers and streams. Findings from the 18-month effort are summarized in the report entitled, Integrating Energy and Water Resources Decision Making in the Great Lakes Basin: An Examination of Future Power Generation Scenarios and Water Resource Impacts.
    Dr. Vincent Tidwell, principle member of the technical staff at Sandia National Laboratories and a technical adviser to the project said, "Although most water used for power generation in the basin comes directly from the Great Lakes, about one-quarter uses water from groundwater or a Great Lakes tributary. That's not insignificant." The report synthesizes several background reports examining technical and policy aspects of power and water in the Great Lakes basin. The technical analysis examines how changes in the type of power generation could affect sensitive watersheds in the future. That analysis is complemented by a review of relevant water and energy policies that identifies gaps and opportunities for improvements.
    According to a release from GLC, new metrics developed as part of the project revealed that approximately one-quarter of all of the watersheds in the Great Lakes basin may be ecologically vulnerable to water withdrawals under certain "low-flow" conditions – conditions that are likely to be more frequent in the future as the impacts of climate change become more severe. Additionally, more than half (57 percent) of the 102 watersheds studied were found to be at moderate to high risk of degrading ecological health due to additional thermal impacts, and 36 percent have water quality that is moderately to highly impaired according to U.S. EPA and state reports. All told, one-fifth of the Great Lakes basin's sub-watersheds rank high for two or more of these risk factors.
    Professor Mark Bain of Cornell University, another project partner, said, "Because of the Great Lakes Energy-Water Nexus project, we now know which areas in the basin are most susceptible to ecological impairment from new water uses, including power production." Using a model developed by Sandia National Laboratories, five future power scenarios were analyzed for the period 2007 to 2035: 1) Business as usual, including use of open-loop cooling where water used for cooling is returned to the river, lake or aquifer from which it was withdrawn; 2) no new open-loop cooling; 3) open-loop cooling totally prohibited; 4) a renewable energy portfolio with 50 percent wind, 25 percent biofuel and 25 percent natural gas; and 5) that same portfolio with carbon capture and sequestration.
    For all five scenarios, water withdrawals would decrease, but by far the largest decreases (87 percent) would occur where there is no open-loop cooling at all. In every case except the open-loop cooling prohibited, thermoelectric water withdrawals would continue to be the basin's predominant water use through 2035. In contrast, consumptive water use would increase under all five scenarios with the largest increase in consumptive use (24 percent) occurring under the carbon capture and sequestration scenario, in part due to increased water required for this process.
    The lowest increase in consumptive use (7.6 percent) would occur under the renewable energy portfolio, reflecting the considerably lower water use associated with natural gas combined cycle technologies as well as wind power generation, which uses no water. Under all scenarios, consumptive uses from the thermoelectric power sector would be lower when compared to industrial and municipal water use sectors. Tim Eder, executive director of the Great Lakes Commission said, "The GLEW project takes us one step further in our understanding of how our energy choices today could impact our water resources in the future."
    Access a release from GLC (click here). Access the summary report and background papers (click here).