Los Alamos National Laboratory Advanced Simulation and Computing (ASC) Program
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Reductions in water usage enhance LANL operations

Recent and future improvements focus on sustainability, efficiency, and capability

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cooling pipes

High Performance Computing (HPC) recently enhanced its supercomputing capability through continued sustainability efforts at Los Alamos National Laboratory (LANL) by reducing the amount of water used to cool supercomputers. HPC has collaborated with the Sanitary Effluent Reclamation Facility (SERF) to creatively solve problems and make innovative changes that improve efficiency. Benefits are focused on increased HPC cooling capability with decreased water use, decreased spending, and increased total cooling capacity.

Increased Efficiency, Decreased Water Use

Recent improvements to operations increased the quality and availability of the non-potable water used for supercomputing cooling. The Strategic Computing Complex (SCC) cooling towers use non-potable water provided by SERF. With planned availability improvements, SERF is on track to provide 96 percent of SCC water, nearly eliminating the need for potable water for cooling supercomputers at the SCC. In the summer of 2019, HPC facilities and SERF worked together to double cycles of water being cleaned and to change the way that water moves around the Laboratory. This new process cuts water use in half by improving water quality. Using cleaner water at the cooling towers enables longer water use and reduces equipment maintenance.

The new measures involve a fundamental change in the water purification process. Previously, water had a long journey before it was cleaned. Now, thanks to a new route that gets the water to filtration equipment sooner, SERF is able to significantly reduce the amount of chemicals needed while sending much cleaner water to HPC. The result is that the Laboratory’s supercomputers can be cooled with half the water than was previously needed. When the cooling towers are finished with the water, it is sent to saturate the Sandia Canyon wetlands.

These changes mean that even though HPC has put more cooling towers online, less water has actually been used this year than in years past. Because of HPC’s work with SERF to increase efficiencies, the water already in use can be stretched further, increasing cooling capability at the SCC and lengthening the time frame before more water is needed for the cooling towers.

“In working with SCC for improvements in efficiency, we have been able to effectively improve the system to the point that we don't have to operate the equipment as hard at SERF to meet the current demands at HPC. Not having to operate the equipment as hard improves our availability and leaves us with excess processing capacity to continue to work towards meeting their future needs and demands.”
— Chris Booton, SERF Operations Specialist

Expanded Supercomputer Cooling Capacity

The current cooling infrastructure for Laboratory supercomputers will soon have the capability to produce approximately 33 megawatts of warm water cooling. This system, which cools Trinity, the current supercomputer, will also be used to cool the next Laboratory supercomputer, Crossroads.

Further changes in operation will enable this warm water cooling system to support two exascale-class systems simultaneously by 2026. Cooling these systems will require about 50 megawatts of warm water cooling. In order to determine the best path forward, Advanced Simulation and Computing (ASC) conducted a study to identify options available for cooling future supercomputing systems. The study concluded that if the plant operates at a 25-degree temperature differential, the current plant can, without new equipment, simultaneously support two exascale-class systems operating at peak capability. With some minor changes, the plant can actually produce over 60 megawatts, providing plenty of warm water cooling for Crossroads and the following two exascale-class systems.

Part of the transition from Trinity to Crossroads will be to change the operations program of the cooling towers. When Crossroads is installed, the set point of the water will be raised to a higher temperature; the new program will also raise the Delta T, which is the difference between the initial water temperature and the temperature of the cooled water. These two steps in operational efficiency will expand the capacity of the current cooling system, saving tens of millions of dollars by preventing the need to purchase new cooling equipment.

Sustainable Efficiency

The positive impact of HPC’s improvements in efficiency can already be seen in the significant reduction of non-potable water and chemicals for treating non-potable water and in the near elimination of potable water use at the SCC for supercomputing cooling. As new exascale-class systems come online at LANL, HPC will increase its Delta T to increase overall cooling capability to 60 megawatts. These changes will enable two exascale-class supercomputers to operate simultaneously at peak efficiency.

HPC is contributing to the Laboratory’s mission and efforts in sustainability through operational changes and solutions that will continue to produce benefits for both the Laboratory and the environment.