Use of Alternative Water Sources for Power Plant Cooling Robert Goldstein (rogoldst@epri.com) Senior Technical Executive, Water and Ecosystems, EPRI ASME Water Management Technology Best Management Practices and Innovations Workshop May 13-14, 2009 Washington, DC
Evaluation of Non-Traditional Water Sources 2
Non-Traditional Water Sources Municipal effluent Oil and gas produced water Agricultural drainage Saline groundwater Considerations Quantity Quality Cooling tower operations (scaling, corrosion, fouling) Public and environmental health 3
Municipal Effluent Used by approximately 60 power plants Largest number in FL, CA, TX and AZ Amount used varies from 0.1mgd to 55mgd Municipal effluent Volume function of population density Quality function of treatment and technologies Individual treatment plant information at http://www.epa.gov/enviro/html/p cs/index.html 4
Wastewater Effluent vs. Thermoelectric Water Use 5
Produced Water In general, less available than sewage effluent Quality highly variable Constituents of concern Oil Grease TDS (30,000mg/l threshold) Chloride Barium Boron Produced water quality data at http://energy.cr.usgs.gov/prov/pr odwat/data.htm 6
Produced Water Production by State 7
TDS Concentrations in Produced Water 8
Agricultural Drainage 1995 national flow 26,800 mgd Quality variable depends on Geology Soil Hydrology Inputs (fertilizers, pesticides) Management practices 9
Irrigation Return Flow at the County Level 10
Saline Groundwater No national data base of available volumes, only depths Quantity estimated for some western states Quality depends largely on geology Quality expected to be similar to produced water in same basin 11
Depth to Groundwater 12
Municipal Wastewater as a Percentage of New Cooling Demand in 2025 13
Agriculture Runoff as Percent of New Cooling Demand in 2025 14
Summary Municipal effluent due to its abundance and quality is a viable alternative source for cooling water supply. Potential greatest in regions of high population density. Agricultural return flow in terms of quantity is comparable to municipal effluent. However additional treatment may be required depending on site-specific water quality. Potential greatest in western states. Oil and gas produced water represents a small quantity of degraded water, often with high TDS concentrations, and is generally not a viable alternative source, although exceptions may exist. Saline groundwater due to its large quantity can be a promising alternative source. 15
Degraded Water Treatment Power plant design and materials tailored to anticipated water chemistry Switching water sources creates possible new water treatment and equipment retrofit needs For instance, ammonia in treated sewage effluent will cause cracking in certain alloys such as admiralty brass In cooling towers, film fill is less tolerant than splash fill to degraded water Use of degraded water usually requires special pre or post cooling water treatment For sewage treatment effluent, need to consider temporal variation in quality 16
Chemical Compatibility Guidelines 17
Water Treatment Technologies Reverse osmosis External pressure forces pure water through membrane Ion exchange Natural exchange materials such as zeolite Synthetic exchange materials include resins and phenolic polymers Applied by mixing or column Impacted by particulate and colloidal matter, solvents and organic polymers Evaporative processes Brine concentrator Chloride and TDS 18
Transport Considerations Pump requirements and costs Pipeline materials and costs Installation costs Routing Chemical composition of water May require secondary containment tsystem for piping i May require pretreatment prior to pumping Redundancy for reliability Shutoff valves for repairing line sections Access shafts Cleaning 19
Pump station costs based on design capacity 20
Pipe Material Types Ductile iron Steel, high density polyethylene Polyvinylchloride Reinforced concrete Fiber reinforced plastic Factors affecting choice Quantity of fluid Quality of fluid Cost Ductile Iron Pipe (material cost per foot) 21
Acquisition Issues Volume and quality guarantees Water rights of other stakeholders Who will pay for delivery Will others users be incorporated into the system What backup source will be provided in case of system failure Costs 22
Treated Sewage Effluent Acquisition Costs 23
USEPA Suggested Guidelines for Water Reuse for Industrial Recirculating Cooling Water 24
Comparison of Federal and State Regulations (R) and Guidelines (G) for the Reuse of Water for Cooling 25
Location, Location, Location 26