IBM Uses Hot Water To Cool Zurich Supercomputer


An IBM water-cooled supercomputer at a Swiss University is heating nearby buildings with its waste heat

IBM has delivered a new water cooled supercomputer to The Swiss Federal Institute of Technology Zurich (ETH) which it claims has cut the carbon footprint of comparable machines by 85 percent.

IBM says that the Aquasar supercomputer marks “a new era in energy-aware computing. According to IBM, it consumes up to 40 percent less energy than a comparable air-cooled machine – but because the waste heat is used to provide warmth to university buildings, Aquasar’s carbon footprint is reduced by up to 85 percent.

IBM is a believer in water cooling, having said that in ten years all servers could be cooled by water. It has been looking at othe rways to make its big iron systems more energy efficent.

Water, Not Air Cooling

Up to 50 percent of an average air-cooled data centre’s energy consumption and carbon footprint is not caused by computing, but is actually caused by powering the necessary cooling systems to keep the processors from overheating. this results in a typical PUE ratio (the power used divided by the power that reaches servers) for a traditional data centre, of around 2.0

IBM began working on Aquasar a year ago as part of the company’s First-Of-A-Kind (FOAK) program, which encourages IBM scientists to explore emerging technologies.

The IBM boffins came up with a supercomputer that consists of special water-cooled IBM BladeCenter Servers. It also holds additional air-cooled IBM BladeCenter servers for comparison purposes. Performance wise, the system delivers six Teraflops and has an energy efficiency of about 450 megaflops per watt.

In addition, nine kilowatts of thermal power are fed into the ETH Zurich’s building heating system.

“With Aquasar, we make an important contribution to the development of sustainable high performance computers and computer systems. In the future it will be important to measure how efficiently a computer is per watt and per gram of equivalent CO2 production,” said Prof. Dimos Poulikakos, head of the Laboratory of Thermodynamics in New Technologies, ETH Zurich.

No Hot Chips

The components and chips within IBM’s Aquasar are cooled by water which is at temperatures of up to 60 degrees C. Essentially, the cooling system is made up micro-channel liquid coolers which are attached directly to the processors, where the most heat is generated.

IBM says that with this chip-level cooling, the thermal resistance between the processor and the water is reduced to the extent that even cooling water temperatures of up to 60 degrees C ensure that the operating temperatures of the processors remain well below the maximally allowed 85 degrees C.

“The high input temperature of the coolant results in an even higher-grade heat at the output, which in this case is up to 65 degrees C.  Overall, water removes heat 4,000 times more efficiently than air,” IBM said.

“With Aquasar we achieved an important milestone on the way to CO2-neutral data centres,” said Dr. Bruno Michel, manager of Advanced Thermal Packaging at IBM Research – Zurich.  “The next step in our research is to focus on the performance and characteristics of the cooling system which will be measured with an extensive system of sensors, in order to optimise it further.”

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Author: Tom Jowitt
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