Model of Implementing Advanced Power Plant Cooling Technologies to Mitigate Water Management Challenges in Texas River Basins
Authors: Clayton Mary E. , Stillwell Ashlynn S. , Webber Michael E. 
Published: May 2012

Texas is a large state whose water resources vary from relatively abundant in the eastern half of the state to relatively scarce in the western half. In addition, Texas is one of five states nationwide that allocates surface water through a system that merges riparian rights and prior appropriation rights. In some locations and climatic conditions, water rights have been over-allocated, creating a predicament where the legal availability of water exceeds the physical availability. Complicating matters, in 2001, the Texas Legislature established an Instream Flow Program, which conducts studies to identify appropriate flow regimes to maintain an ecologically sound environment. The findings of these instream flow studies could create challenging streamflow requirements that might cause problems for water allocation planning and management. This case study analyzes the full execution of water rights in eleven of twenty-three total river basins in Texas and the corresponding relationship to water availability. Under the full execution scenario, each water rights holder diverts the full volume allocated by a water permit with zero return flow. While this full execution scenario is not necessarily practical since most water rights holders return a portion of the diverted water after use, the Texas Commission on Environmental Quality uses the full execution water availability model to evaluate new water rights applications. Using the full execution as a baseline, we created a model to estimate the potential decrease in total water diversions in Texas river basins through the implementation of three alternative cooling scenarios at thermoelectric power plants: 1) converting current open-loop cooling technologies to closed-loop cooling towers, 2) converting all current cooling technologies to hybrid wet-dry cooling, and 3) converting all current cooling technologies to dry cooling using air-cooled condensers. Total annual diversion savings for the three alternative cooling scenarios were determined and translated into human equivalence to show the significance of implementing these cooling technology changes. By implementing these alternative cooling technologies at the plants in all eleven of the river basins considered in this analysis, water diversion could be reduced by as much as 247 to 703 million m3 annually. These diversions can supply enough water for 1.3 to 3.7 million people for one year (each using 0.53 m3 per day). Improvement in volume reliability, the percentage of total demand that is actually supplied over a time period of interest, was also examined to determine the effectiveness of converting existing thermoelectric cooling technologies to alternative cooling technologies that reduce total water diversions. Our results suggest that implementation of alternative cooling technologies at Texas thermoelectric power plants do not translate into significant improvements in volume reliability but can dramatically reduce total water diversion volumes.