A technique that substituted a reusable liquid refrigerant in place of evaporative-water cooling towers when outside temperatures are low enough to make that feasible earned Sandia National Laboratories engineers and others a Department of Energy environmental award.

Sandia engineer David J. Martinez, NREL scientists David Sickinger and Kevin Regimbal, Tom Carter of Johnson Controls and DOE’s Matt Graham received the DOE’s Federal Energy and Water Management Award for helping to halve the amount of water used to cool a high performance computer data center. The technique saved the data center at the National Renewable Energy Laboratory (NREL) in Golden, Colo., 1.15 million gallons of water in 2017.

The refrigerant’s cooling process does not require an electrically powered pump. Instead, it relies on simple convection. The hot water from the data center causes the refrigerant to turn from liquid to gas, which removes energy through the phase change. The refrigerant then rises to a heat exchanger, where the outside air cools it off so that it can re-liquefy. The liquid refrigerant then returns to the original reservoir via gravity and the process starts again.

According to Martinez, a system using the process, called hybrid thermosyphon cooling, will be installed at Sandia by 2019.