Through the retrofit of boilers and enhanced control systems at the Hal C. Weaver Power Plant achieved reduction in NOx emissions and energy savings. The University power plant is a combined heating and power facility, supplying the campus with electricity as well as useful heat salvaged from waste heat. Over a ten year period, 1996 though 2006, the use of natural gas as fuel was significantly reduced. The amount of NOx was reduced by 807.1 tons and CO2 by 2.4 million tons.
Technologies used include the use of a real-time dispatch model of the entire cooling / heating / power (CHP) system to optimize the use of stand-by equipment, the use of a quench vessel to reduce the need for standby steam turbines and the reduction of in-plant parasitic loads. Boiler retrofits using flue gas recirculation and variable frequency drives on two back-up grandfathered boilers (150K and 500K lbs/hr) reduced emissions to meet a voluntary emissions reduction permit requirement and allow the boilers to be banked at 1 MMBTU/hr. These and other technologies are applicable in similar industries. In 1996, the power plants overall thermal efficiency was 60%, compared to a typical combined-cycle power facilitys thermal efficiency of only 40%. By 2006, the UT power plant efficiency had been increased to 76% due to plant modifications and process optimization. The total plant efficiency as of September 2009 was 83% and is projected to improve further. The university recently commissioned a new GE LM-2500+G$ combustion turbine and HRSG, a new 15,000 ton chiller plant, an inlet air cooling system for two combustion turbines and a 4 million gallon thermal energy storage system will come on line September 2010. The efficiency in 2009 allowed the University to return to 1977 fuel and CO2 emissions levels though the campus added 9 million new square feet.
Comments: Based on a conservative projected campus load growth, assuming $6/mmbtu for future purchased natural gas it appears that the entire investment of about $143 million will be paid off in about 2021. This is very good considering that the equipment has a useful life of about 40 years.
Details of Reductions
Comments: For the time period, 1996 through 2010, the cumulative fuel savings due to efficiency gains have totaled over $40 million.
1,107.1 - ton of
Comments: Based on a baseline total volume released in 2006, the total volume of NOx released in 2007 was 807.1 Tons less. The projects listed below are projected to reduce NOx released by another 300 Tons because GT 6 was demolished and replaced with a new LM 2500+G4, GE turbine and the operating hours for the Westinghouse 251 B10 are being reduced and replaced by hours on the GE turbine.
2,400,000.0 - ton of
Additional Information :
Emissions reductions by projects implemented since 2004 (tons CO2/year):
Steam Turbine #9 11,000
Cooling Tower #1 2,750
Boiler FGR/NOx Retrofit 11,000
Steam/Feed Water By-Pass 27,500
Chilling Station 6 3,933
Inlet Air Chilling 6,600
Thermal Energy Storage 2,200
Chilling Station Modernization 1,100
Gas Turbine # 10 21,967
Electric System Description: The University of Texas at Austin main campus is a dense urban campus of over 16 million square feet in 200 buildings serving 70,000 students, faculty, and staff. The buildings are connected through a district energy system, with all utilities centrally generated on campus by The Utilities & Energy Management Department. Connections to the surrounding city electrical grid exist only for emergency backup, providing the University independence and versatility in generating the electricity, chilled water, heating steam and other utilities required on campus. Eighty percent of the 16 million square feet on campus is research oriented, operating 24 hours a day, 7 days a week, and 365 days a year. The research facilities conduct around $511 million dollars in contract and research grants annually, demanding a variable and uninterrupted supply of energy at all times. A reliability of 99.998% has been maintained over the last 35 years for all delivered energy. Even with Texas boasting the largest amount of wind energy in the country and several nuclear plants, the mix of coal and natural gas used to generate grid electricity does not compare to the efficiency of the combined heating and power facilities on the university campus. The disparity between self-generated energy on campus and purchased grid energy will continue to widen, as efficiency improvement projects are continuously implemented on campus.