Today these components are aligned side by side

How to limit the power of supercomputers and data centers The issue is important, because these beasts of calculation are also monsters energy - it is estimated that larger data centers can consume as much electricity as a city of 50,000 inhabitants. With a paradox: barely half the energy used to calculate itself. The rest is largely absorbed by the cooling systems (cold, air conditioners and fans groups). Because the processors and electronic components emit a strong heat, up to 80 C. Beyond that, it is the failure.

Engineers at IBM Zurich research centre think found a track to improve energy efficiency: cool machines with water, because liquids are better drivers heat than air. The idea is not completely new: already in the 1980s, the Cray-2 supercomputers were fully immersed in a liquid. Today, the doors of computer cabinets contain a chilled water loop. IBM wants to go further, by bringing the water closest to the processor. "We are inspired by the human bloodstream, which is divided into smaller ships," explains Bruno Michel, responsible for research on the thermal interfaces to Zurich Research Center of IBM.

The result is to halfway between the computer and the piping: water flows through a network of tubes of copper that iterates through each array component cabinets of the supercomputer. These tubes are feeding small boxes placed directly on the processor.

Cooled by hot water

Originality of the device: the water used for cooling is... hot. "We get the same result with water at 60 C that with air at 15 C, says Bruno Michel." And this allows reuse of 80 of the heat thus generated. "According to IBM, the water coming out of the cabinets could be used to feed networks of heat (in temperate countries), or systems of desalination (in warm climates). A condition, of course, that data centers be installed as close as the concerned fencing infrastructure, which is far from being the case today. "Such a system will be very complex to implement across a Computing Center, because will need to implement the exchangers, isolating circuits, etc.," said Jean-Pierre Panziera, responsible for calculating high performance in Bull.

Last may, IBM has delivered the first computer of this type, Aquasar, installed at the Federal Institute of Technology Zurich (ETH). Composed of two cabinets cooled by water and air-cooled Cabinet, it feeds the building's heating system. Its computing power is less that 6 teraflops (6,000 billion operations per second floating-point), placing in the category "small" calculators. It is primarily a prototype used to test and validate the technology, that IBM plans to implement in real centres of calculation by 2012.

Fluid in the chips

The next step is much more futuristic: circulating coolant in microprocessors. The origin of this idea, there is the willingness to stack various "hearts" that make up the processor. Today, these components are aligned side by side. By stacking them, reduces their connections, which accelerates the exchange of data, leverages the computing power and limit consumption. But these "sandwiches" of electronic components pose many problems, particularly in terms of heat and isolation.

Researchers from IBM Zurich and EPFL (Ecole polytechnique fédérale de Lausanne) have therefore imagined place tunnels of 100 micrometres between each layer of processors, to circulate fluid. A mock-up was presented, showing several Silicon plates surmounted by two pipes. But the research are just beginning. It will include finding the ideal liquid, water and coolant with each of the advantages and disadvantages. "We believe that this technology will require between 10 and 15 years of development," said Bruno Michel, IBM. By then, much water will cast bridges... and perhaps in supercomputers.