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Iowa State University Power Plant

Iowa State University Power Plant. Iowa State University Utility Enterprise. Operates as a rate-based enterprise Charges university entities for the utilities they consume Employs 78 people Operates two facilities on main campus and two satellite facilities

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Iowa State University Power Plant

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  1. Iowa State UniversityPower Plant

  2. Iowa State University Utility Enterprise • Operates as a rate-based enterprise • Charges university entities for the utilities they consume • Employs 78 people • Operates two facilities on main campus and two satellite facilities • Has the capability to provide all the energy needs of the university

  3. Iowa State University Utility Enterprise • Overall budget of $35.7 million • Coal - $13.7 million • Limestone - $412,000 • Ash disposal - $780,000 • Purchased electricity - $2.05 million • Last year the cost of these items averaged $45,000 every day

  4. Power Plant • 6 boilers – total capacity of 900,000 lbs of steam per hour – peak load of 488,000 lbs/hr • 4 turbine-generators – total capacity of 46 megawatts – peak load of 34.1 megawatts • 5 chillers – total capacity of 21,000 tons of cooling – peak load of 15,169 tons • 4 air compressors – total capacity of 4,000 cubic feet per minute – peak of 1800 cfm • 1 water plant – capacity of 1,000,000 gallons per day – peak requirements of 1.3 million gpd • Replacement value of $282 million

  5. FY08 Plant Production • Steam produced – 2,623,141,000 lbs • Steam to campus – 1,095,721,000 lbs • Chilled water – 33,343,000 ton-hrs • Electricity consumed – 200,886,000 kwh • Generated electricity – 151,831,000 kwh • Purchased electricity – 45,956,000 kwh • Coal burned – 154,463 tons • Limestone used – 14,749 tons • Ash produced – 28,178 tons

  6. Other Utility Consumption • Natural Gas used – 24,584,000 cubic feet • Domestic water used – 313,524,000 gallons • Sewage generated – 202,684,000 gallons

  7. Mechanical Distribution Systems • Steam tunnels – 4.5 miles • Direct buried steam – 2.6 miles • Chilled water – 5.3 miles • Domestic water – 8.3 miles • Natural gas – 4.5 miles • Sanitary sewer – 10.3 miles • Storm sewer – 25.2 miles • Compressed air – 3.5 miles • Replacement value of $113 million

  8. Electrical Distribution Systems • High voltage electrical cables – 16.7 miles • Electrical transformers – 515 • Electrical substations – 7 • Telecommunications cables – 90 miles • Street, sidewalk and parking lot lights – 1900 • Traffic lights – 7 • Replacement value - $53 million

  9. Cogeneration • Sometimes called combined heat and power or CHP • Defined as using a single fuel source to simultaneously produce thermal energy and electrical power • Thermal efficiencies of more than 70% are attainable as compared to typical utility plant efficiencies of 35-42% • Iowa State started cogenerating in 1891 and typically averages 50-55% thermal efficiency

  10. Cogeneration

  11. ISU Energy Source • Currently burning 100% coal • Coal comes from southern Illinois and western Kentucky • Coal is barged to Muscatine, Iowa and loaded onto trucks • Trucks deliver coal to ISU and haul grain back to the Mississippi to be loaded onto barges • Approximately 6200 trucks per year, 25 per day

  12. ISU Energy Source • Coal is blended to our specifications in Muscatine at the dock facility • Coal Quality • Eastern Bituminous coal • 11,800 BTU/lb • 2.4% sulfur (medium sulfur) • 8.5% ash • 10.5% moisture

  13. Emissions Limits • ISU Power Plant had no emissions limits prior to the 1970’s • Clean Air Act of 1970 required improvements in emissions performance at facilities across the country • Emission limits have become more stringent over time • New plant equipment typically had to comply with emissions limits that existed at the time of construction • Today’s proposed emissions regulations are typically retroactive to existing equipment • Plants must retrofit pollution control equipment, change to different cleaner fuels, or replace equipment with new that meets new regulations • Implementation of new regulations are now often delayed due to litigation by environmental groups

  14. Emissions Limits

  15. Emissions Controls • ISU retrofitted pollution control equipment for particulate on all boilers through the late 1970’s • Switched from high sulfur Iowa coal to washed Iowa coal and eastern coals • Installed new circulating fluidized bed boilers in 1988

  16. Mechanical Dust Collectors • Retrofitted to existing boilers in the mid-1970’s • Collect particulate by centrifugal force • Efficiency drops as ash particles get smaller • Collection efficiency is 90% at best • Boiler 5 is fitted with a mechanical dust collector only • Opacity when Boiler 5 is operating is typically 15-20% • Emissions rate is 0.35 lb/mmBTU

  17. Mechanical Dust Collector

  18. Electrostatic Precipitator • Retrofitted to Boilers 3 & 4 in the late 1970’s • Collect particulate by electric charge • Collection efficiency is about 97% • Boilers 3 & 4 are fitted with a mechanical dust collector and an electrostatic precipitator in series • Opacity when Boilers 3 & 4 are operating is typically less than 10% • Emissions rate is 0.05-0.08 lb/mmBTU

  19. Electrostatic Precipitator

  20. Electrostatic Precipitator

  21. Fabric Filter or Baghouse • Baghouses were originally supplied with Boilers 1 & 2 • Collect particulate by filtering through 1,354 filter bags, each 6” in diameter by 14 feet long • Collection efficiency exceeds 99.5% • Opacity on Boilers 1 & 2 is less than 5% • Emissions rate is 0.025 lb/mmBTU

  22. Fabric Filter or Baghouse

  23. Fabric Filter or Baghouse

  24. Fabric Filter or Baghouse • Fabric filters are used on many material handling systems in the plant as well • Ash handling systems • Coal, lime and ash silo vents • Coal handling system transfer points • Primary use is to control fugitive dusts as materials are transferred from conveyor to conveyor, into silos, etc.

  25. Circulating Fluidized Bed Boilers • Burns coal in conjunction with limestone • Limestone constituents react with the sulfur to produce CaSO4 which is removed with the ash • Eliminates more than 90% of the sulfur dioxide emissions • Low combustion temperatures and staged combustion reduce the emissions of nitrogen oxides

  26. Circulating Fluidized Bed Boilers

  27. Stoker Boilers • These boilers have no means of controlling sulfur dioxide or nitrogen oxide emissions • Fuel is purchased with sulfur contents low enough to meet the requirements • Future regulatory requirements for SO2 or NOX will require installation of additional pollution control equipment, fuel switching or other compliance methods

  28. ISU Compliance Efforts • Operate equipment as efficiently as possible, minimizing coal consumption and emissions • Operate pollution control equipment properly • Operate most efficient units as much as possible • Continuously look for alternatives to improve performance

  29. Emissions Summary

  30. Emissions Reduction Opportunities • Continue cogeneration • Reduces coal burn by 15,000 tons per year • Reduces limestone consumption by 1,600 tons per year • Reduces ash production by 2,600 tons per year • Saves over $1.5 million per year • Results in emissions reductions of • 37,000 tons less carbon dioxide • 310 tons less sulfur dioxide • 50 tons less nitrogen oxides

  31. Emissions Reduction Opportunities • Conserve Energy • Shut off lights and equipment that you aren’t using • Utilize energy efficient devices • Adjust thermostats • Energy conservation is 100% efficient at emission reductions, if you don’t use the energy, there are no emissions • Saves money for other things

  32. Emissions Reduction Opportunities • Add more pollution control equipment • Effective but very expensive • Baghouse - $6.0 million per boiler • Scrubbers - $12-15 million • Install new coal boiler - $60+ million

  33. Emissions Reduction Opportunities • Switch fuels • Low sulfur eastern coals – costs are 25-50% higher • Low sulfur western coals – BTU content 25% lower, not suitable for ISU boilers • Biomass • BTU content is 40% lower, and density is 50% of coal • Volume of fuel required increases nearly 4 times • Emissions of NOX increases due to fuel volatility • Transportation costs can make biomass fuels not economical • Natural gas – costs are 100-150% higher

  34. Emissions Reduction Opportunities • Wind Energy • ISU is participating in development of a wind farm near Ames • Cost of energy appears economical • Have requested 5 megawatts of capacity which would provide about 7% of current energy consumption • Capacity factor expected to be 37-38%

  35. Questions?

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