Alternative Cooling for Palomar Energy Project Overview of dry and wet cooling NH3 emissions from wet tower Wet towers and Legionella What is “beneficial use” of reclaimed water? What are other potential uses of reclaimed water? Impacts of dumping Palomar brine in ocean outfall Cost of dry versus wet cooling Bill Powers, P.E. Border Power Plant Working Group (BPPWG)
Wet Tower Water Demand • 500 MW combined-cycle: 4,000 acre-ft/yr (3.6 x 106 gal/day) • Fate of water: 80 - 90% lost to evaporation, 10 - 20% converted to brine with salt content of 4,000 to 5,000 mg/l. • Life of power plant: ~50 years • Retrofit to dry system: Possible, though more difficult and expensive than incorporating dry cooling in original design.
Impact on Cost of Power • CEC/Electric Power Research Institute (research consortium of electric power utilities) February 2002 report on dry cooling states: • Busbar production cost: includes all the costs of generating electricity and the plants being compared - since the cooling system costs are a small fraction of the total plant capital, operating, and fuel costs, these ratios are normally close to unity • Translation - cooling system choice, wet or dry, has no significant impact on cost of power.
Nearby States and Dry Cooling • Nevada State Engineer’s Office, April 2002: "Technology is available, which can produce significant amounts of electricity using air-cooled systems. State Engineer…does not believe it is prudent to use substantial quantities of newly appropriated ground water for water-cooled power plants in one of the driest places in the nation…"
Nearby States and Dry Cooling • Texas currently has 1,650 MW of dry-cooled combined-cycle capacity in operation and 550 MW under construction. 450 MW dry plant permitted for El Paso. • Arizona recently (2002) required dry cooling on one project and rejected a second project due to concerns over impacts on local groundwater supplies.
Nearby States and Dry Cooling • Mexico currently has seven dry-cooled combined-cycle plants in operation totaling ~3,500 MW, and is a world leader (on percentage basis) in use of dry cooling. • Mexico uses common sense approach: Locate dry plants near major load centers, to minimize (1) transmission line construction cost and (2) efficiency losses associated with long transmission lines from remote plants near water sources.
California and Dry Cooling • California Gov. Gray Davis, Border Governor’s Conference Declaration, June 2002: “Promote the development of an environmental strategy for new electrical generation plants in the border region with the goal of protecting air quality, and, where possible, conserving water resources in the region.”
NH3 Emissions - Stack • NH3 is air toxic and PM2.5 precursor • 2004 Federal NH3 inventory requirement as PM2.5 precursor • > 50% of PM2.5 in winter is ammonium nitrate in San Joaquin Valley • Stack limit 10 ppm, or 23.1 lb/hr at 100% load, 62 oF, no duct firing: 101 tons/yr • State-of-the-art NH3 slip level: 2 ppm • Per turbine SCR cost addition to reach 2 ppm guarantee level: 25% (+$250,000)
NH3 Emissions - Wet Tower • HARRF treated water NH3 concentration: • 1st quarter 2002: 31.6 mg/l, 3,589 lb/day • 2nd quarter 2002: 18.1 mg/l, 2,137 lb/day • Discharge limit: 25 mg/l, 1,877 lb/day • NH3 in reclaimed water to cooling tower: • (13 x 106 l/day)(20 mg/l) = 260 kg/day NH3 emissions = 104 tpy from wet tower (assume 100% volatilization rate in tower)
Removing NH3 in Reclaimed Water • Three LA area refineries use nitrication plants to remove NH3 in reclaimed water (20 mg/l NH3 concentration) prior to use in wet cooling towers. • Reason - wet towers built with admiralty brass pipes for use with salt water, NH3 attacks admiralty brass. • Cost of 4 Mgd nitrification plant: $5MM (Ondeo Degremont BIOFOR biofiltration system)
NH3 Emissions and PM2.5 • U.S. EPA promulgated the Consolidated Emissions Reporting Rule (CERR) on June 10, 2002. • All States required to inventory direct emissions of PM2.5 and NH3. • States must commence reporting point source emissions of PM2.5 and NH3 on June 1, 2004.
NH3 Emissions and PM2.5 • If region is “NH3 limited,” a major component of the airborne NH3 forms ammonium nitrate PM2.5 in winter. • If region is “NH3 saturated,” a small component of airborne NH3 forms PM2.5 in winter, although sources of NH3 contribute to the NH3 saturated condition and must be controlled as effectively as NH3 sources in “NH3 limited,” regions.
NH3 Recommendations for Palomar Energy Project • Minimize NH3 air toxic and PM2.5 precursor emissions issues by: • Limiting turbine NH3 slip emissions to 2 ppm • Use of dry cooling to eliminate NH3 emissions stripped from reclaimed water used in the wet cooling tower
Wet Towers and Legionella • Cooling Technology Institute (CTI) 2000 white paper on wet cooling towers and Legionella: • 4,000 deaths/yr in US from Legionella • Cooling tower drift aerosols major exposure pathway • Assume all towers contain Legionella • No substantial “body of support” for best practices to control Legionella in cooling towers
Best Practices and Legionella • Best practices are “best guess” according to CTI - bacteria is very resistant. • No specific level of organism can be assigned as safe. • Best practices minimize, but do not eliminate, risk. • Legionella capable of rapid repopulation of previously cleaned systems.
Best Practices and Legionella • Most agencies do not recommend testing for Legionella on routine basis. • Difficulties in interpreting Legionella test results and in using test results as basis for control. • Testing for Legionella is recommended in the event of an outbreak, to identify sources and effectiveness of disinfection procedures.
Legionella and Reclaimed Water • CTI states periodic hyperhalogenation may be necessary for cooling systems using reclaimed water. • Hyperhalogenation is the maintenance of 5 ppm free halogen residual for at least 6 hours. • Hyperhalogenation will discourage development of large populations of Legionella and may eliminate need to conduct higher risk off-line emergency disinfection procedures.
CTI White Paper • Despite deaths and known cooling tower exposure pathway, cooling tower disinfection practices are not currently regulated in US • In contrast, Legionella disinfection practices are heavily regulated in England and Australia
England and Legionella • Employers who operate cooling towers face stiff penalties and individual prosecutions if they fail to ensure regular cleaning and maintenance of cooling towers. • $300,000 in fines and fees imposed on two factories in Wales for failure to maintain rigorous O&M program on cooling towers (1998 incident).
US and Legionella • Two workers die of Legionella at huge Ford plant in Cleveland in 2001 - cooling towers are suspected source. • Ford claims regular maintenance program in place for cooling towers - Ford agrees to “step up” maintenance to avoid reoccurrence. • No legal action.
Palomar and Legionella Data Responses • Water treatment program will include stringent maintenance of cooling system, regular inspections, periodic flushing, use of sodium hypochlorite as biocide. • Strict maintenance necessary to prevent plugging, as plugging would adversely affect tower efficiency.
Questions on Legionella Data Responses • Will strict cooling tower O&M be maintained continuously over 50-year life of plant, given no regulatory oversight of any kind? • What is potential extent of Legionella bloom in tower before plugging is so bad that control room notices tower efficiency drop? What is time lag between noticing problem and complete cleaning of cooling tower?
Recommendations to Address Legionella Issues • Make payments to nearby residents at a rate that makes them willing participants in a large-scale, lifetime Legionella exposure experiment. • Have residents sign liability disclaimer in exchange for payments. • Or, use dry cooling at the site and eliminate the Legionella issue at the source.
Is Power Plant Cooling “Beneficial Use” of Water? • U.S. Bureau of Reclamation justification for grants to the San Diego Area Water Reclamation Program, which includes HARRF: “Greater use of reclaimed water results in decreased dependency on potable imported water including from the Colorado River.”
Summary of Escondido’s Reclaimed Water Program • $80MM cost over 5 - 7 year period. • Program funded by grant from Bureau of Reclamation and zero interest loans from State Water Resources Control Board, Division of Clean Water Programs. (source: City of Escondido Public Works website)
Summary of Escondido’s Reclaimed Water Program • 9,000,000 gal/day tertiary treatment capacity at Hale Avenue Resource Recovery Facility (HARRF). • 25 miles of reclaimed water distribution piping. • 2,000,000 gallon underground reclaimed water storage reservoir to provide equalization of variable flow demands.
Beneficial Uses of HARRF Reclaimed Water • Landscape irrigation. • Avocado grove irrigation (Ramona example). • San Pasqual Groundwater Basin Management Project – groundwater recharge using HARRF reclaimed water. • In addition to provide extensive grant funding for HARRF reclaimed water program, Bureau of Reclamation provided $360,000 for San Pasqual planning studies. (as of January 2001)
Beneficial Uses of HARRF Reclaimed Water • The three potable water displacement uses cited for reclaimed waster on the previous slide meet the “beneficial use” standard set by Bureau of Reclamation in providing grant funding for the HARRF reclaimed water program. • If properly planned and executed, these three uses can take all the reclaimed water HARRF can produce and displace an equal amount of Colorado River water imports.
Palomar Energy Project and Reclaimed Water • Use of reclaimed water at the Palomar Project will not displace one gallon of potable imported Colorado River water, as the plant could not be permitted in Escondido using potable water. • Sending 3.5 to 4.0 Mgd of HARRF reclaimed water to the Palomar Project will result in the underutilization of 25 miles of reclaimed water pipeline, and deny reclaimed water to uses that legitimately displace potable water imports.
Palomar Energy Project and Reclaimed Water • Applicant and Escondido indicate that reclaimed water production can be increased from 9 to 18 Mgd if more reclaimed customers appear. • Who will pay for this expansion? Applicant? Federal and State taxpayers, who are apparently paying for or heavily subsidizing the first 9 Mgd? New customers? • Selling ~1/2 HARRF reclaimed water output to Palomar now essentially short-circuits any use of reclaimed water in avocado groves or for groundwater recharge for the foreseeable future. • Grove irrigation and groundwater recharge are the two legitimate “big ticket” beneficial uses of HARRF reclaimed water in the Escondido area, not power plant cooling.
Can Bureau of Reclamation or SWRCB Object? • Yes • Will they? No. • Reason? Preference to leave ultimate decisions on reclaimed water uses to local authorities, apparently even if these decisions conflict with stated objective of grant/subsidy program. • Missing element: Insistence by funding agencies or watchdog groups that reclaimed water uses displace potable water imports and reduce our dependency on those imports.
Downstream Impacts of Power Plant Brine Discharge • Palomar will produce nearly 1 Mgd of high salt content cooling tower blowdown. • Current plan is to bypass HARRF and discharge into San Elijo Lagoon ocean outfall. • San Elijo Joint Powers Authority (SEJPA), Encinitas area, has constructed reclaimed water plant immediately adjacent to ocean outfall. • Locally reclaimed treated wastewater has high salt content (1,100 mg/l) and limited use for irrigation applications. Must be diluted with potable water to below 1,000 mg/l for summer irrigation use.
Downstream Impacts of Power Plant Brine Discharge • Current salt content of HARRF treated wastewater is 200 mg/l lower than local treated wastewater. • HARRF water considered “sweet water” by SEJPA, and has been identified by SEJPA as only feasible option for reducing reclaimed water salinity. Use of HARRF water would eliminate need to blend potable water with local reclaimed water. • SEJPA is planning to expand reclaimed water program by drawing water out of ocean outfall, in negotiatons with Escondido to this end. (2-14-02 SEJPA board meeting minutes)
Downstream Impacts of Power Plant Brine Discharge • “City of Escondido wants to finalize negotiations with Sempra Energy prior to finalizing any agreement with SEJPA.” • “The Sempra agreement may impact the parameters of the Escondido/SEJPA agreement.” (9-12-02 SEJPA board meeting minutes) • PE Note: In fact, dumping Palomar Energy cooling tower brine into the ocean outfall could derail the Escondido/ SEJPA agreement, as SEJPA will have little use for high salt reclaimed water.
Power Plant Reclaimed Water Use “Ripple Effect” • 4 Mgd of reclaimed water goes to power plant, displacing 0 Mgd of potable water imports. • $80MM reclaimed water system has only ½ design capacity of 9 Mgd available for potable water displacement projects. • No HARRF capacity available for “big ticket” potable water displacement projects without major new investments in HARRF tertiary treatment capacity expansion from 9 Mgd to 18 Mgd. • Discharge of cooling tower brine in ocean outfall short-circuits promising reclaimed water expansion program along ocean outfall route.
System Capital Cost Factor (%) O&M Cost Factor (%) Douglas fir wet tower (lowest cost option) 100 Plume abatement wet tower 250 – 300 Air-cooled condenser 250 – 325 Cost of Dry vs. Wet Cooling at Palomar Energy Project[EPA 316(b) New Facilities Rule, Econ. And Egr. Analysis, App. A, pg. AppA-14] 100 125 – 150 175 – 225
Cost of Dry vs. Wet Cooling at Palomar Energy Project[EPA 316(b) New Facilities Rule, Econ. And Egr. Analysis, App. A, pg. AppA-14] • EPA cost estimates for wet and dry cooling systems do not include cost of slight fuel penalty using dry cooling or the cost of water or wastewater disposal for wet systems. • In the case of the Palomar Energy Project, the cost of water and wastewater disposal using wet cooling dominates the fuel penaly associated with dry cooling.
Sempra Wet vs. Dry Cost Evaluation • July 17, 2002 Sempra submitted wet versus dry cooling cost evaluation to San Diego APCD. • Excluding fuel penalty, Sempra calculates $1.8MM/yr cost for air-cooled condenser (ACC) and $3.6MM/yr for plume abatement wet cooling tower. • Fuel penalty estimated at 1.0 to 1.5% for optimized ACC at Escondido site designed to produce rated steam turbine load at all ambient site tempertures. • Assuming 1.5% fuel penalty, 500 MW, 0.8 capacity factor, 6.86 MMBtu/MW-hr (HHV), additional fuel required by dry plant is ~360,000 MMBtu/yr.
Sempra Wet vs. Dry Cost Evaluation • At $3.33/MMBtu, mean SoCal gas price predicted by CEC for 2002 – 2012 timeframe, the 1.5% fuel penalty imposed by dry cooling at the Palomar site equals $1,200,000/yr in added fuel cost. • Annualized dry cooling cost is: $1,800,000/yr + $1,200,000/yr = $3,000,000/yr • Cost of wet cooling = $3,600,000/yr • Sempra cites high dry cooling fuel efficiency penalty in evaluation, though provides no details.
Dry Cooling Noise and Visual Bulk • Noise ~50 dbA at 400 ft. using ultralow noise fans. Nearest residence is ~1,000 ft. from plant property line. • 70 ft. overall height at site with adequate space such as Palomar site. • In contrast, the proposed plume abatement tower will be 65 ft. high and have a visible plume up to 40 ft. high, or 105 ft. total height, for an average of one daylight hour every other clear winter day.
Summary of Dry Cooling Advantages at Palomar • No reclaimed water demand, frees reclaimed water for potable water displacement uses. • No brine discharge to ocean outfall. • No PM10 emissions. • No NH3 or PM2.5 precursor emissions. • More cost-effective than plume abatement tower at Palomar site.