July 24, 2017

Energy-savings tank project to enter testing phase

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Troy Fedderson | University Communication

Troy Fedderson | University Communication

The University of Nebraska–Lincoln will begin to fill and test a new specialized water tank that is designed to reduce energy costs and increase heating and cooling system efficiency.

The 8.1-million-gallon tank, which is scheduled to go online in spring 2018, will work like a battery, holding chilled water in reserve to cool campus buildings during peak demand periods. The system reduces energy costs by chilling stored water when energy use on campus is low, primarily at night and on weekends.

"The thermal energy storage tank allows us to shift the energy used to chill water away from peak-demand periods during the day to lower-demand times at night and on weekends," said Stefan Newbold, assistant director and engineering manager for facilities planning and construction. "That shift helps flatten the university's electric load profile, eliminating sharp increases in energy used and resulting in money savings."

.Employees examine the inside of the thermal energy storage tank before it is sealed for filling and testing. Baffles at the top and bottom will reduce water circulation within the tank. The holes along the tank at left will hold temperature gauges that will allow for monitoring along the entire 100-foot height of the tank.
Troy Fedderson | University Communication
Employees examine the inside of the thermal energy storage tank before it is sealed for filling and testing. Baffles at the top and bottom will reduce water circulation within the tank. The holes along the tank at left will hold temperature gauges that will allow for monitoring along the entire 100-foot height of the tank.

Energy cost savings for the $11.9 million City Campus tank are estimated to be between $850,000 and $900,000 annually. A smaller, 2.8-million-gallon tank in use since 2012 on East Campus has recorded yearly energy cost savings of approximately $350,000.

The new tank is located immediately north of the landscape services building near 17th and Y streets. Construction started in November 2016 and will be substantially completed this fall. Earlier this summer, an underground bore project connected 36-inch specialized pipe from the tank to the campus chilled water system. The bore successfully installed two 630-foot-long stretches of pipe under Antelope Parkway, linking to the campus system near 16th and W streets.

Starting the week of July 24, workers will begin to fill the tank with water and test it for leaks. Charlie Griesen, construction coordinator for Facilities Management and Planning’s Utility Services, said the filling and testing is scheduled to last about two weeks.

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Craig Chandler | University Communication
The new thermal energy storage tank is located on the north side of City Campus, immediately south of the Devaney Sports Center (left) and Nebraska Innovation Campus (right).

Construction continues on the support building immediately west of the tank.

Tank capacity can supply chilled water to City Campus for six to eight hours during peak demand periods. The tank will be full automated and controlled remotely from the City Campus Utility Plant near 14th and W streets.

The tank itself is made of welded plate steel, which will be skinned by a three-inch-thick layer of insulation covered by decorative aluminum paneling. A retention pond designed to handle storm water runoff from the top of the tank is also being integrated into the site.

.Workers bore under the Antelope Valley creek bed to install a 36-inch-wide, 630-foot-long pipe that connects the thermal energy storage tank to the university's chilled water system.
Troy Fedderson | University Communication
Workers bore under the Antelope Valley creek bed to install a 36-inch-wide, 630-foot-long pipe that connects the thermal energy storage tank to the university's chilled water system.

The tank is nearly 100 feet tall with a diameter of 120 feet.

When complete, the tank will provide electrical demand savings, expand redundancy to meet the university’s cooling needs and reduce wear and tear on existing chillers. The City Campus tank, which could provide air conditioning to approximately 1,600 average-sized homes, is also designed to supply chilled water to future university facilities built on the east side of Salt Creek.

Photo story: Energy-savings project