Location: United States, Florida, St. Lucie
Application: Energy Storage System
Calmac, Trane, St. Lucie Case
It’s all about the kids and St Lucie, Florida public schools kept that in mind when they reduced the annual cost of energy by more than $5M, using thermal energy storage to generate ice at night and help cool the buildings during the day. This savings allowed for 70 new teachers and significantly reduced class size. – A win for the kids, the administration and local taxpayers!
Faced with necessary chiller plant upgrades, rising utility costs, and a commitment to provide a climate that would provide a comfortable learning environment for 40,000 K-12 students, the St. Lucie County School District’s energy advisory board decided that a Thermal Energy Storage (TES) system, with CALMAC® Ice Tanks and Trane® EarthWise™ chillers would provide the best value over the next 15 years.
A TES System provides increases efficiency and dehumidification, which allows for less energy consumption. The chiller plants were designed with highly-reliable Trane® air- and water-cooled chillers, ranging from 600 to 1200 tons, to accommodate the varied needs of the sites. Running at cooler temperatures, the chiller plants provide better dehumidification, an important benefit in the humid Florida climate, and operate more efficiently, with less pumping and fan energy consumption. After comparing options, the district selected the superior design and operation of the CALMAC® IceBank® energy storage tanks for the plants combined with a Trane TRACER® control system complete with advanced Intelligent Services. In one of the locations, the chiller plants at three schools, situated in close proximity of each other, were replaced with a centralized chiller plant built in-between them. The centralized plant, which includes over two miles of underground piping to connect the schools to the plant, allowed the district to reduce chiller capacity by 300 tons which cut cost and significantly provided the overall efficiency of all three schools.
Initial success leads to district rollout: After feasibility studies and school board approval, Centennial High School was selected as the first site for a Trane chiller plant upgrade with thermal energy storage. The project reduced the high school’s annual electric bill over 50 percent. Based on this success, St. Lucie County School District moved forward with plans to upgrade 13 district locations.
Trane chiller plant upgrades with thermal energy storage at 13 St. Lucie County School District sites have resulted in lower operating expenses, with average annual utility costs reduced 30 percent to 40 percent. “A few years ago our utility costs were about $12 million,” said Marty Sanders, director of growth management, maintenance and facilities, St. Lucie School District. “We’re now under $7 million.” Using the thermal energy storage to shift load from peak to non-peak hours has also reduced demand charges, and resulted in rebate incentives from Florida Power & Light and a three- to five-year payback on the project. “If we reduce our demand during the peak daytime hours, the utility company doesn’t have to build as many power plants and it also helps reduce brown outs,” said Sean Murray, energy manager, St. Lucie School District. “Being part of the solution is good.”
Trane, the Circle Logo, TRACER and EarthWise are trademarks of Trane in the United States and other countries. CALMAC® and IceBank® are trademarks of CALMAC. All trademarks referenced are the trademarks of their respective owners.