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San Diego State University’s Energy-Saving Projects

By Bill Lekas

San Diego State University has an active and expanding energy and environmental program, the cornerstone of which is the central plant.   One of the earliest cogeneration plants in any university in California (3 megawatts installed in 1985), the new plant has been in full operation for a number of years and sets a gold standard for power production, flexibility and efficiency.  

The new plant is a combined cycle (gas turbines with steam turbine bottoming cycle) and is rated at more than 14 megawatts.    The plant now allows the University to stage the gas turbines and steam turbine to meet the minimum campus heat load and maintain optimum performance.  University minimum electric load has increased from approximately 5 megawatts to 6.8; with a peak load in the 13 megawatts range and rising with new construction.  The heat rate on the original plant was approximately 13,000 BTUs/kwh and our new plant operates at 10,500 BTUs/kwh.  This reflects an efficiency improvement of over 30 percent.

That plant is the cornerstone of San Diego State’s energy program, but thanks to that success and the multi-millions saved, the University has been able to deploy a monitoring based commissioning program as well as an ever-expanding energy and environmental demonstration program.  The demonstration program includes: 

• Solar hybrid lighting, which uses a parabolic mirror that brings light into the building through a bundle of fiber optic cables to fixtures equipped with acrylic rods that glow from the light from the mirror.  When the available light reaches foot candles that have been set on the photo sensor, the fluorescents dim to 10 percent.  Energy savings are around 45 percent.

• An advanced solar project is demonstrating uses of parabolic mirrors that focus sunlight on a center core of gallium arsenide chips, which are cooled by a primary cooling loop.  The secondary loop is tied into the domestic hot water and is supposed to provide 85 gallons of 185 degree water.  San Diego State is in the testing phase now and each unit provides 1 KW of electricity.  The composite efficiency of this unit is in the 70 percent range. 

• Low level waste heat recovery which can be used in conjunction with the solar cogeneration, or with any application where low level waste heat can be used to offset energy load.

All of the base central plant work, as well as the demonstration programs (and a campus-wide energy management system) are accompanied by an aggressive commissioning and utility re-charge process that ensures high visibility energy accounting.  The campus has received multiple awards for energy management, best practices in monitoring based commissioning, recycling, food waste diversion and water conservation efforts through central irrigation control. 

Other current energy efficiency projects include three additional building commissioning efforts which have historically saved in the range of 15 percent in energy usage; parking structure lighting retrofit which has dropped energy consumption for lighting by 30 percent; and the retrofit of the existing marquee off of freeway 8 to a full color LED display.  This is projected to drop demand from a max of 155 KW down to roughly 35 KW with an improved visual display and less glare at night.

Because of the University’s ability to monitor the energy from these technologies, they look to continue to be a test bed for green technology as well as implementation where applicable on campus.  The continual monitoring of the cogeneration serves to maintain the plant at its optimal operation and indicates problems before they become costly.  Much of the success of the plant can be attributed to San Diego State’s team of people who operate and support the plant, as well as the green campus interns and the Enviro-business student group who has focused their efforts on conserving energy through outreach.

San Diego State University's Trolley Station

Bill Lekas is San Diego State University’s overall energy efficiency and conservation coordinator,  including interfacing with the academic community in sustainability and green technology.