“Power Plant Cooling Towers and Cooling Water Issues” - Hot Topic Hour on February 16, 2012

Power plants use significant quantities of water, mostly for cooling purposes while generating electrical energy. However, proposed rules on power plant water intakes and discharges, as well as the increasing scarcity of fresh water, will drive changes in water use and management strategies at power plants. Tighter air pollution rules may also drive utilities to upgrade cooling water systems to help reduce SO₃ and particulate emissions. Upgrading cooling water systems raises other issues, such as maintaining water quality to prevent scaling and fouling. Our speakers this week provided a wide range of information for utilities to consider as they develop strategies for complying with the upcoming rules, and for meeting future power plant water demands.

Ivan A. Cooper, P.E., B.C.E.E., Practice Leader at Golder Associates NC, Inc, stressed the increasing importance of water management in the power sector. Water is becoming more scarce and roughly 40 percent of the fresh water withdrawals in the U.S. are for power plant use. Since half of existing power plants are within ten miles of a municipal wastewater treatment plant, he believes that power plants will increasingly look to reclaimed wastewater for cooling water systems.  He went on to describe a number of concerns with using reclaimed water, including biofouling, corrosion and scaling. He also outlined a number of impediments to doing so including transport, storage and discharge issues. Ivan reviewed three case studies in Maryland, Florida and California, and stressed the importance of managing public perceptions when undertaking a water reuse project.    

Mark Gerath, Technical Director, Water Resources, AECOM Environment, discussed strategies for complying with the Section 316(b) rule, which is scheduled to be finalized in July 2012.  The rule will not require closed loop cooling water systems.  It will, however, require upgrades to intake structures to reduce “impingement” of aquatic life.  Mark said that the retrofits are fairly straightforward, but achieving an impingement mortality (IM) performance standard may be difficult.  He expects the IM standards to be downplayed or even eliminated in the final rule. The rule will also require costly studies based on Best Professional Judgment (BPJ) to reduce “entrainment” of aquatic life.  While EPA was attempting to allow some flexibility, Mark pointed out a number of inconsistencies in the proposed rule related to the completion of these studies.

Larry Schimmoller, P.E., Global Technology Leader - Water Reuse at CH2M Hill, reviewed two case studies where reclaimed municipal wastewater is used for cooling water at power plants.  The Denver Water Recycling Plant is a traditional reclamation plant that generates water for not-potable uses. The largest customer is Xcel Energy’s Cherokee Power Plant which uses up to 10 MGD of reclaimed water. The second example was the Western Corridor Recycled Water Project on the east coast of Australia near Brisbane. This project includes three advanced water treatment plants which supply reclaimed water to two power plants and a drinking water reservoir. The water is of very high quality and must meet drinking water standards.  

Kaveh Someah, with Ovivo USA, LLC, discussed cooling water intake structures including screens and methods for removing debris, fish recovery techniques and fish deterrent systems using sound, light or air bubbles. He mentioned that while fish deterrent systems are common in Europe, EPA’s focus on survival percentages and impingement mortality rates discourages the use of such systems in the US.

Matthew L. Haikalis, Technical Resource Engineer at Veolia Water Solutions & Technologies of Crown Solutions, discussed water treatment for recirculating cooling water systems. Primary concerns include the ability to control biofilm and microbiological activity, and the impact of cycling on scaling and corrosion. He discussed a number of treatment options, stressing that solutions will differ based on the quality of the raw water, system metallurgy and system volume.

The Bios, Abstracts and Photos are linked below.

Bios, Abstracts, Photos - 2-16-12.htm