[Beowulf] Water-cooled IBM supercomputer to heat buildings

Eugen Leitl eugen at leitl.org
Thu Jun 25 05:41:52 PDT 2009


June 24, 2009 12:07 PM PDT

Water-cooled IBM supercomputer to heat buildings

by Manek Dubash

IBM and the Swiss Federal Institute of Technology at Zurich plan to build a
water-cooled supercomputer whose surplus heat will be re-used to heat the
university's buildings.

The Aquasar supercomputer will be located at the ETH Zurich facility, and it
will start operations next year, the partners said in an announcement on

Water flows along copper pipes in a blade server used in the Aquasar
supercomputer.  (Credit: IBM)

The supercomputer will combine two rack-mounted IBM BladeCenter servers, each
containing multiple blades with a mixed population of IBM PowerXCell 8i and
Intel Nehalem processors. It is expected to deliver a peak performance of
about 10 teraflops.

The installation will re-use heat directly for in-building heating. IBM
estimates that the wate-rcooling scheme will reduce the system's carbon
footprint by up to 85 percent and save up to 30 tons of carbon dioxide
annually, compared with standard cooling approaches. The comparison
calculations are based on average yearly operation of the system and on
in-building heating energy being produced by fossil fuels, the company said.

The energy-consuming refrigeration units used by almost every data center
consume about half of the a data center's energy. Aquasar will need no such
equipment. As a result, it should reduce overall energy consumption by 40
percent, according to IBM.

"Energy is arguably the number-one challenge humanity will be facing in the
21st century. We cannot afford anymore to design computer systems based on
the criterion of computational speed and performance alone," Professor
Poulikakos of ETH Zurich, the leader of the Aquasar project, said in a
statement. "The new target must be high-performance and low-net power
consumption supercomputers and data centers. This means liquid cooling."

The system is the product of an extended joint research project between ETH
and IBM scientists, focused on chip-level water-cooling. It also encompasses
a concept for "water-cooled data centers with direct energy re-use" proposed
by scientists at IBM's Zurich Lab.

Aquasar's use of warm water rather than cold water for cooling is unique and
IBM-patented, a spokesman for the company said. Water, which is about 4,000
times more efficient as a coolant than air, will enter the system at 60
degrees C. This will keep the chips in the system at operating temperatures
below their maximum of 85 degrees C, according to IBM.

The high input temperature of the coolant results in an even higher-grade
heat as an output, which in this case will be about 65 degrees C, the company

The system uses jet impingement cooling, which means that water makes direct
contact with the back of the chip via micro-channels in the heat sink,
according to research papers by the IBM and ETH scientists involved in the
Aquasar project. "This method incurs neither the thermal resistance overhead
of a base plate, nor the overhead and reliability problem of thermal
interface materials, and thus is promising for removing highest-power
densities," according to one paper.

Pipelines from the individual blades link to the server rack's water-pipe
network, which in turn is connected to the main water transportation network.
Aquasar will need about 10 liters of water for cooling, pumped at some 30
liters per minute, IBM said. The cooling system is a closed circuit: the
water is heated by the chips and cooled to the required temperature as it
passes through a passive heat exchanger, delivering the removed heat directly
to the heating system of the university.

Aquasar will be used by the computer science department at ETH Zurich for
multiscale flow simulations related to nanotechnology and fluid dynamics.
Researchers plan to show that solving scientific problems efficiently can be
performed in an energy-efficient manner.

Manek Dubash of ZDNet UK reported from London.

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