Iowa State University Power Plant

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Iowa State UniversityPower Plant
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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

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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

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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

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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

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Other Utility Consumption

• Natural Gas used 24,584,000 cubic feet
• Domestic water used 313,524,000 gallons
• Sewage generated 202,684,000 gallons

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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

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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

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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

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Cogeneration
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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

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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

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Emissions Limits

• ISU Power Plant had no emissions limits prior to
  the 1970s
• 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
• Todays 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

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Emissions Limits
Pollutant Stoker Boilers CFB Boilers
     
Sulfur Dioxide 5.0 lb/mmBTU 1.0 lb/mmBTU (30 day average) 1.42 lb/mmBTU (3 hr average) 90 removal
Nitrogen Oxides none 0.40 lb/mmBTU (30 day average) 0.40 lb/mmBTU (3 hr average)
Carbon Monoxide none 200 ppm
Particulate 0.389 lb/mmBTU 40 Opacity 0.034 lb/mmBTU 10 Opacity
Fluoride none 0.039 lb/mmBTU
Lead none 0.0015 lb/mmBTU
Beryllium none 0.00063 lb/mmBTU
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Emissions Controls

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

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Mechanical Dust Collectors

• Retrofitted to existing boilers in the mid-1970s
  
• 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

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Mechanical Dust Collector
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Electrostatic Precipitator

• Retrofitted to Boilers 3 4 in the late 1970s
• 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

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Electrostatic Precipitator
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Electrostatic Precipitator
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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

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Fabric Filter or Baghouse
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Fabric Filter or Baghouse
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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.

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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

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Circulating Fluidized Bed Boilers
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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

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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

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Emissions Summary
      Sulfur Dioxide Sulfur Dioxide Nitrogen Oxides Nitrogen Oxides Particulate Matter Particulate Matter
  Boiler Efficiency Percent of Steam Production DNR Limit Average 2005-07 DNR Limit Average 2005-07 DNR Limit Average 2005-07
Boiler 1 87 30 1,029 200.7 412.0 74.9 35.0 13.6
Boiler 2 87 35 1,029 217.9 412.0 75.8 35.0 19.0
Boiler 3 82 14 5,795 1,067.9 None 128.7 584.1 Combined 32.8
Boiler 4 82 20 6,178 1,516.8 None 183.4 584.1 Combined 38.4
Boiler 5 78 2 4,886 117.4 None 9.6 584.1 Combined 18.1
Boiler 6 78 0 0 0 None 0 584.1 Combined 0
                 
Total   100 18,917 3,120.7   472.4 654.1 121.9

Note All emissions are expressed in tons per year Note All emissions are expressed in tons per year Note All emissions are expressed in tons per year Note All emissions are expressed in tons per year Note All emissions are expressed in tons per year
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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

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Emissions Reduction Opportunities

• Conserve Energy
• Shut off lights and equipment that you arent
  using
• Utilize energy efficient devices
• Adjust thermostats
• Energy conservation is 100 efficient at emission
  reductions, if you dont use the energy, there
  are no emissions
• Saves money for other things

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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

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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

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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

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Questions?