A cooling system under development could save millions of gallons of water per year and hundreds of millions of gallons nationally if widely implemented, says the developers.

The thermosyphon cooler hybrid system, built by Johnson Controls, is currently being tested at the National Renewable Energy Laboratory in Colorado. It cools like a refrigerator but without the energy needs of a compressor.

The system also is scheduled to be installed next year at Sandia National Laboratories’ computing center in New Mexico, where it is expected to save 4 to 5 million gallons of water annually.

Many data centers today use water to remove waste heat from servers. The warmed water is piped to cooling towers, where a separate stream of water is turned to mist and evaporated. The process removes heat from the piped water, which returns to chill the installation. But large-scale replenishment of the evaporated water is needed to continue the process. Thus, an increasing amount of water will be needed worldwide to evaporate heat from the growing number of data centers, which themselves are increasing in size as more users put information into the cloud.

By contrast, the prototype thermosyphon cooler hybrid system uses a liquid refrigerant instead of water to carry away heat. Water heated by the computing center is pumped within a closed system into proximity with another system containing refrigerant. The refrigerant absorbs heat from the water so that the now-cooled water can circulate to cool again. The heated refrigerant vaporizes and rises in its closed system to exchange heat with the atmosphere. As heat is removed from the refrigerant, it condenses and sinks to absorb more heat, and the cycle repeats.

According to David J. Martinez, engineering project lead for Sandia, there is no water loss like there is in a cooling tower and chemicals are not added. The system only requires outside air cool enough to absorb the heat.