According to an engineering project lead, a cooling unit installed on the roof of Sandia National Laboratories’ supercomputer center saved 554,000 gallons of water during its first six months of operation last year.

The unit, called a thermosyphon cooler, also saved over 195,000 kilowatt hours of electricity during the same time period by making it unnecessary to pump thousands of gallons of water around the clock through energy-intensive mechanical chillers.

The decrease in water use at the facility in Albuquerque, N.M., could be the model for cities and other large users employing a significant amount of water to cool supercomputer clusters, said David J. Martinez, engineering project lead for Sandia’s Infrastructure Computing Services.

The thermosyphon cooling unit intercedes passively. Its refrigerant rests in a shell that surrounds an outgoing pipe like a glove on a hand, absorbing heat until the liquid evaporates into a gas, like boiling water becomes steam. The gas rises in vertical pipes until it reaches the upper limits of the device. Then it gives up its acquired heat to the atmosphere, coalesces back into liquid and sinks down ready to cool again.