i/o Data Centers is using a rare cooling technology at its 180,000-square-foot facility.

At its 180,000-square-foot Phoenix colocation facility, i/o Data Centers is using a thermal energy storage system with a unique component: ice balls. Hundreds of plastic water-filled spheres a little larger than softballs make up part of Cryogel's Ice Ball Thermal Storage system.

The balls float in four tanks filled with a glycol solution that is chilled to 22 degrees. The company uses cheaper night-time energy to freeze the balls, according to PC World. Energy stored in frozen balls is released during the day as they melt and supplements cooling capacity of the system, creating savings for the data center's operators.

According to Cryogel, the solution saves about $1,250 per kilowatt. Users of the system will recoup their costs within three to five years after purchase, says ZDNet UK. These claims have been questioned by HP.