USE OF IMPAIRED WATERS in POWER PLANT COOLING TOWER SYSTEM: REVIEW OF REGULATIONS AND FEASIBILITY ANALYSIS

In 2000, the freshwater withdrawn for industrial use in the U.S., including mining, industrial process usage, power generation, etc., has reached 45% of the total daily freshwater withdrawal of 346 billion gallons. Among these industries, thermoelectric generation is the largest freshwater user with a withdrawal of 136 BGD. Fierce competition for this valuable resource will force difficult decisions to be made about allocation priorities and water availability for electric power production. Studies have shown that impaired waters can be used as alternative water sources for certain applications, including makeup water in electric power plant cooling systems. Among all possible impaired waters that could potentially be used in power production, secondary treated municipal wastewater is the most common and widespread source. Review of regulations that govern water reuse revealed that there are no federal regulations specifically addressing water reuse and that a number of states have implemented their own regulations. Several states were investigated for specific regulations and/or guidelines related to water reuse in power plant cooling water systems.The geospatial analysis performed in this study was designed to evaluate the feasibility of using treated municipal wastewater for cooling in power industry. By utilizing the geoprocessing tools of a geographic information system (GIS), this study evaluated if the water demand of a particular facility can be satisfied by nearby Publicly Owned Treatment Works (POTWs). Datasets of 110 power plants proposed for development and 11785 POTWs were evaluated as part of this feasibility analysis. Estimated cooling water needs for the proposed power plants were compared with the total wastewater flowrates discharged by nearby POTWs. Data analysis revealed that 81% of the proposed power plants would have sufficient cooling water supply from POTWs within a 10 mile radius, while 97% of the proposed power plants would be able to meet their cooling water needs from POTWs located within 25 miles from these plants. On average, 1.15 POTWs were needed to completely satisfy the cooling water demand for each of these power plants. In other words, one fairly large POTW within a reasonable distance from each power plant could meet most of its cooling water needs.Dataset of 407 existing coal fired power plants was also evaluated using the same process. All of the existing power plants were assumed to be renovated to wet recirculating cooling systems regardless of their original design. Results indicate 49.4% of the existing power plants would have sufficient cooling water supply from POTWs within a 10 miles radius; 75.9% of the existing power plants would have sufficient cooling water supply from POTWs within a 25 miles radius. For those power plants which have sufficient water supply, an average number of 1.46 POTWs are required to satisfy the cooling water demand.The tools developed in this study can be used to evaluate a number of scenarios for alternative cooling water supply needed for energy generation in the future. It is clear that the reclaimed municipal wastewater can and will likely play a more prominent role in this critical industrial sector.