Coal to Boilers
The total coal flow indicates the total amount of coal currently being burned each hour in all operating boilers. The coal flow to the boilers varies continuously as the university’s energy demands change. For reference, coal is delivered to the power plant in semi trucks. Each truck contains 25 tons of coal.
The university utilizes coal as its energy source. The coal is burned in 5 different boilers to produce high pressure steam at 400 psi and 750 deg F. Typically 3 or 4 boilers are operated to provide the steam. The operators closely monitor boiler operations to maximize efficiency and minimize emissions into the environment.
The coal used by Iowa State comes from southern Illinois and western Kentucky. The coal is shipped on the Mississippi River by barge to Muscatine Iowa where it is blended together and loaded onto trucks. The trucks deliver the coal to Iowa State and then pick up corn, soybeans and other commodities to haul back to southeast Iowa.
Lime to Boilers
The total limestone flow indicates the total amount of limestone currently being burned each hour in Boilers 1 and 2, the two circulating fluidized bed boilers. The limestone flow varies as the university’s energy demands vary.
The two fluidized bed boilers are the most efficient boilers at the power plant and are specially designed to minimized emissions. The fluidized bed boilers burn limestone with the coal while they produce steam. The limestone reacts with the sulfur in the coal and forms calcium sulfate. This material is collected with the ash. The addition of the limestone reduces emissions of sulfur dioxide by over 90%. The limestone comes from a quarry near Iowa Falls, Iowa and is trucked to the power plant.
Ash Produced
The total ash produced indicates the total amount of ash currently being produced each hour from all operating boilers at the power plant. The quantity of ash produced varies as the university’s energy demands vary.
All coals contain impurities that do not burn. These impurities end up as boiler ash. In the fluidized bed boilers, limestone is added to remove sulfur dioxide from the combustion gases. All the limestone also ends up as ash.
There are two types of ash, bottom ash which is the larger particles that come from the bottoms of the boilers, and fly ash which is collected by pollution control equipment before the combustion products are discharged up the stack.
All ash is used for beneficial purposes in accordance with Department of Natural Resources requirements. The ash is used for quarry reclamation, soil stabilization and to manufacture a compost product.
Purchased Power
The purchased power is the amount of power that is purchased from others each hour. The amount of purchased power varies according to a schedule developed by the operators each day.
Iowa State has the capability to generate all the electricity for the campus with its own generators or can choose to purchase electricity. The primary goal for the plant operators is to provide utility services to the campus in a safe, reliable and efficient manner, at the lowest possible cost each day. One of the methods to achieve this goal is to balance electricity produced by our own generators and electricity purchased from others.
The operators always maximize the "Combined Heat and Power" process which produces the lowest cost electricity. However, the university requires more electricity than can be produced through this process. The operators then evaluate the lowest cost method of providing the additional electricity and either by producing with our generators or purchasing it from others.
Iowa State purchases electricity on the Midwest Independent System Operator (MISO) open market. MISO manages and operates the electrical grid in the upper Midwest. Iowa State purchases electricity on the Day Ahead market and schedules power a day in advance for each hour of the following day. Operators at the Iowa State power plant work closely with operators at the City of Ames power plant to coordinate power purchases from MISO whenever it is more economical.
Iowa State also purchases electricity from a wind farm located approximately 15 miles northeast of Ames. The quantity of the power available from the wind farm varies continuously with the wind speed.
400 lb. Steam Produced
The total 400 lb steam flow represents the total pounds of steam currently being produced each hour by all operating boilers. The quantity of steam produced varies as the university’s energy demands vary.
Coal is burned in the boilers to produce high pressure steam at 400 psi and 750 deg F. The high pressure steam is used to produce electricity or chilled water. Most of the high pressure steam is used in the Combined Heat and Power process to first produce electricity and then is used on campus for heating or to produce chilled water.
ISU Generated Power
The total generated electricity represents the total amount of electricity being produced each hour by the operating generators in the power plant.
Iowa State has four turbine generators that are used to produce electricity. Typically 2 or 3 generators are operating continuously. The generators provide power to substations on campus at either 13,800 volts or 4,160 volts. The power is then distributed from the substations to the campus buildings.
All of the generators at Iowa State’s power plant are used as part of the Combined Heat and Power process. High pressure steam enters the steam turbine which drives the generator to produce electricity. As electricity is produced, energy is removed from the steam which lowers its pressure to 90 psi and its temperature to 500 deg F.
A portion of the steam is then removed or extracted from the turbine and is used for heating campus buildings used to produce chilled water. The remaining portion of steam that is not extracted continues through the steam turbine to produce more electricity. As more steam is extracted, efficiency of the power plant increases.
Campus Power
The total electrical consumption represents the total amount of electricity being used by the university each hour. The total represents the sum of all electricity being generated on campus and the electricity that is being purchased.
The total includes all electricity being used on the main campus including the Iowa State Center and the power plant. This total does not include Ames Laboratory, the football stadium complex or the facilities at the Veterinary Medicine campus.
Campus Steam
The total steam to campus represents the total amount of steam being used by the campus buildings each hour.
High pressure steam is used first in the power plant to produce electricity. After producing electricity the low pressure steam at 90 psi is sent from the power plant through the steam tunnel system to the campus buildings. The steam is used in the buildings for heating, to produce hot water and for process and/or research needs. The steam is condensed back to water as it gives up its energy to the buildings. The condensed steam or condensate is returned back to the power plant and is pumped into the boilers to be made into steam again.
Campus Cooling
Total chilled water production represents the total amount of cooling required each hour by the campus buildings. Chilled water production is measured in tons of cooling. One ton of cooling is equivalent to 12,000 BTU per hour. For perspective, a typical home air conditioner is rate at 2 to 3 tons of cooling.
Iowa State utilizes five large chillers to provide chilled water for cooling the campus buildings. Four of the chillers are located in the campus power plant. The fifth chiller is located in the north chilled water plant.
The chillers produce chilled water at 40-42 deg F. This chilled water is pumped through the building equipment to cool the building. The chilled water picks up heat from the buildings and returns to the chillers at up to 55 deg F. The chillers cool the water again and return it to the buildings. At peak times, over 25,000 gallons of water are pumped through the buildings every minute.
The chilled water is used to provide comfort cooling for the building occupants but is also used for cooling research equipment, computer equipment, animal rooms, etc. Iowa State must provide chilled water to the campus 365 days per year.
