Ice-Based Energy Storage Saves Florida School District $5M per Year
The St. Lucie School District’s (SLCSD) in Florida is using ice-enhanced cooling as part of its energy cost reduction strategy. Over the past seven years, the district has installed CALMAC’s IceBank energy storage tanks in 15 schools. The school district’s energy management program has created a 30-40 percent reduction in annual energy costs, totaling about $5 million.
Before implementing CALMAC’s thermal energy storage and other energy efficiency upgrades, SLCSD was ranked number 60 out of 67 county school districts in terms of energy costs per square foot within the state. Now, the district ranks among the top 20 and recently received the “Energy Efficiency Leader Award” from Trane.
Two different utilities, with different rates structures, currently supply SLCSD with energy. This led to the use of partial and full energy storage systems among the different schools in the district. Centennial High School installed a full energy storage system to take advantage of incentives that cover most of the cost of installation. Enough cooling is stored in the form of ice during the night to cool the campus from noon–9 p.m. without assistance from the chiller. As a result, the school has seen a 50 percent reduction in cooling costs, saving $300,000 per year.
Partial energy storage systems are used in the district for schools that do not have incentives, but instead have a differential between daytime and nighttime electrical costs due to a $10 per kW demand charge. Facilities with partial storage have smaller, more efficient chiller equipment that works in tandem with the ice-based thermal energy storage. Using this strategy, Lincoln Park Academy, for example, lowered energy costs by $334,000 within the first year of installation, a 32 percent reduction in cooling costs.
A partial storage system works like a hybrid car, CALMAC explained. The chiller acts like the smaller engine in the hybrid car and switches on and off as needed to assist the storage in meeting the entire load.
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