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To accommodate the growing demands for power on campus, in particular for the Albert Sherman Center now under construction, the school is expanding its power plant—and in this case, getting bigger means growing greener.
The $47 million project is adding nearly 14,000 square feet to the turbine hall on the south side of the power plant to accommodate a new 7.5 megawatt, gas-fired, combustion turbine and associated equipment that will boost the plant’s capacity to generate steam, electricity and chilled water, doing so in ways that actually lower the plant’s carbon footprint.
“The new turbine is a derivative of a jet engine,” said Joseph Collins, director of energy resources. “A conventional jet engine is designed to produce thrust. This turbine is designed to turn a generator and produce heat.” Tour the power plant.
Fueled by natural gas, the new turbine will spin a shaft attached to a generator to produce electricity. At the other end of the turbine, exhaust flowing at 950 degrees will be funneled into a heat recovery steam generator (HRSG) to produce some 60,000 pounds of high-pressure steam per hour. That steam will do triple duty: It will drive two of the plant’s existing electric generators, then move through the campus’ steam-line network to heat buildings and drive compressors that make chilled water for the campus’s cooling systems.
“We are called a cogeneration plant, because we get two outputs from one input,” Collins said. “The fuel is the input, and steam and electricity are the outputs.”
Generating electricity at the point of use saves up to 30-percent of the fuel that would have been used by a distant power plant to meet the campus needs. This occurs because power is lost when electricity is transported great distances over power lines, so more must be generated to compensate for those losses. Furthermore, when the new gas turbine is operating, one of the plant’s 35-year-old gas and oil-fired boilers will be taken off-line and kept in reserve as an emergency back-up. Since natural gas burns cleaner than oil, and the new jet turbine is highly efficient, the expanded power plant will actually have lower greenhouse gas emissions, despite its added generating capacity.
Another environmental benefit of the new turbine will be the incorporation of a catalytic reduction system to remove pollutants before the exhaust gasses are discharged through the existing smokestack. “We’ve designed this project to be supportive of our campus sustainability goals,” said John Baker, associate vice chancellor of facilities management. “The school and hospital operations continue to grow, but we want to do so in ways that limit our carbon footprint.”
Skanska USA is building the power plant project, which also includes construction of a new control room for the entire plant. When the expansion is completed, the plant’s maximum electrical output will increase from 10 to 17.5 megawatts. The existing plant produces all the steam and chilled water currently needed on campus, and about half of the electricity used. The expanded plant will be able to meet nearly all of the campus’s electrical demand, even after the opening of the Sherman Center, but the school will maintain a connection to the external utility grid to handle peak demand and for a back-up resource.
Construction of the plant expansion began last spring. The new turbine, HRSG and associated equipment are expected to be installed and ready for testing this fall.