IBM Supercomputer Cools Servers with Hot Water

IBM researchers have created "Aquasar," a supercomputer that uses hot water to cool blade servers. Aquasar consumes up to 40 percent less energy than similar air-cooled systems, and the waste heat is being used to help keep buildings at a Switzerland university warm.

IBM has built a supercomputer that is cooled by hot water.

IBM has shipped the supercomputer, called "Aquasar," to the Swiss Federal Institute of Technology Zurich-or ETH Zurich-that contains the new cooling system.

Aquasar, announced July 2, consumes up to 40 percent less energy than a similar air-cooled machine, and by using waste heat to warm buildings at the university, can reduce the system's carbon footprint by up to 85 percent.

IBM officials said their engineers in Switzerland and Germany began developing Aquasar as part of the company's First-Of-A-Kind program. Through the FOAK program, IBM scientists are tasked with working with customers to find solutions to business problems.

In this case, the issue was power consumption and cooling. IBM officials said that up to 50 percent of the energy consumption and carbon footprint of an average air-cooled data center is generated by the system to cool the computers, rather than the computers themselves.

The Aquasar compute cluster, which is fully operational, has a combination of IBM BladeCenter blade systems, some of which use the new hot-water cooling system, and others that are air-cooled.

In all, Aquasar has three BladeCenter H chassis with a total of 33 BladeCenter QS22 servers-each of which is powered by two PowerXCell 8i processors-and nine BladeCenter HS22 systems that contain two Intel Xeon 5500 series "Nehalem EP" chips.

Two of the BladeCenter H Chassis are water-cooled, with a total of 22 BladeCenter QS22 and six HS22 servers.

Each system comes with a liquid cooler for each processor, as well as input and output pipelines. The liquid coolers are attached directly to the processor, which is cooled by water that is up to 60 degrees Celsius, or 140 degrees Fahrenheit. The system will keep the processors well below the maximum temperature of 85 degrees Celsius, or 185 degrees Fahrenheit, according to IBM.

The water in the Aquasar system is hotter than that used in typical liquid-cooled systems. IBM estimates that water removes heat 4,000 more efficiently than air, and does a better job of transporting that heat.

In the closed-circuit cooling system, the water that is heated by the processor is run through a passive heat exchanger, which removes much of the heat. That heat is then directed to the university's heating system for use to help keep the buildings warm.

Aquasar is part of a three-year research program called "Direct use of waste heat from liquid-cooled supercomputers: the path to energy saving, emission-high performance computers and data centers." Along with ETH Zurich and IBM Research-Zurich, ETH Lausanne, also in Switzerland, is part of the program.

According to IBM, Aquasar can reach performances of 6 teraflops (trillion floating point operations per second), with an energy efficiency of about 450 megaflops per watt.

The company estimates that 9 kilowatts of thermal power are fed into the university's building heating system.

"With Aquasar we achieved an important milestone on the way to CO2-neutral data centers," Bruno Michel, manager of Advanced Thermal Packaging at IBM Research-Zurich, said in a statement. "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 optimize it further."