The Alamo Heights Independent School District (AHISD) in San Antonio, TX, recently employed ice-based energy storage technology to cool more than 325,000 sq ft across five buildings on its high school campus. The energy storage tanks were provided by Calmac.

The school district, which was already using several solar systems, a 500-kW solar system and another five solar arrays totaling 400 kW to help power daily operations, needed a way to reduce energy consumption during expensive peak demand hours. Installing Calmac’s IceBank® tanks at its high school campus has allowed the district to store cheap nighttime energy from the grid in the form of ice that can then be melted to cool buildings during the day. As a result, the district has reduced peak energy consumption by more than 20%, despite an increase in square footage and student population.

“The use of Calmac’s ice-based energy storage tanks has really allowed us to capitalize on the most cost-effective energy from the grid,” said Mike Hagar, assistant superintendent for business and finance at AHISD. “We had heard about energy storage in the past, but the technology has exceeded expectations.”

Renewable energy sources fluctuate based on weather conditions, making technologies like solar systems an unpredictable source when looking to lower energy consumption during peak demand hours. Calmac’s energy storage supplements solar systems by offering a reliable source for low-cost cooling that can be called into action at any time, as is the case with AHISD. The use of storage technology allows the district to decouple when grid energy is purchased from when it is utilized. With Calmac’s system in place, AHISD can store a reserve of energy generated during off-peak hours and utilize it when there isn’t enough solar power to meet peak consumption.

“This is the first project that I’ve worked on involving a thermal storage system,” said Lowell Tacker, principal with LPA, Inc. and lead in the high school art building’s expansion project. “Given the size and usage of the campus, we felt a thermal storage system appropriate. This assumption was proven without a doubt when we looked at the numbers. We added over 40,000 sq ft to the AHISD and the energy costs per square foot have actually gone down considerably. For any project of this scale and usage, there’s no reason not to consider energy storage technology.”

Mark MacCracken, CEO of Calmac, said the Texas school district is seeing several positive results from the installation.

 “The versatility of ice-based energy storage has created a number of benefits for the Alamo Heights Independent School District — from enabling the utilization of less expensive off-peak electricity to maximizing the effectiveness of solar and allowing the district to expand without the need for extra chillers,” he said. “School districts are expanding to meet the needs of the growing student population at the same time that fiscal pressures are growing. Making energy smart decisions now through the use of energy storage will help prepare these districts for the future.”