Aquasar is a supercomputer (a high-performance computer) prototype created by IBM Labs in collaboration with ETH Zurich in Zürich, Switzerland and ETH Lausanne in Lausanne, Switzerland. While most supercomputers use air as their coolant of choice, the Aquasar uses hot water to achieve its great computing efficiency. Along with using hot water as the main coolant, an air-cooled section is also included to be used to compare the cooling efficiency of both coolants. The comparison could later be used to help improve the hot water coolant's performance. The research program was first termed to be: "Direct use of waste heat from liquid-cooled supercomputers: the path to energy saving, emission-high performance computers and data centers." The waste heat produced by the cooling system is able to be recycled back in the building's heating system, potentially saving money. Beginning in 2009, the three-year collaborative project was introduced and developed in the interest of saving energy and being environmentally-safe while delivering top-tier performance.
History
Development
The Aquasar supercomputer first came in to use at the Department of Mechanical and Process Engineering, at the Swiss Federal Institute of Technology Zurich (ETH Zurich) in 2010. ETH Zurich is one of two schools that is a part of the Swiss Federal Institute of Technology with the other school being ETH Lausanne. High energy efficiency, environmentally friendly computing, and high computing performance were a few of the main interests in the development of the Aquasar. A key part of being environmentally friendly was the focus of attempting to lower the output of carbon dioxide emissions. 50% of an air-cooled data center's energy consumption and carbon pollution actually comes from the cooling system of the data centers rather than from the actual computing process. The creation of the Aquasar started in 2009. It was a part of IBM's First-Of-A-Kind (FOAK) program (a program encouraging IBM researchers and clients to develop potential new technologies to assist with real world problems in business). One other supercomputer would later use the same idea of a hot water coolant in their developments, the SuperMUC supercomputer. Future development of more powerful supercomputers also explored the possibilities of using on-chip cooling as their main cooling source to achieve greater computer efficiency.
Further Exploration of Hot Water Coolant
An academic paper written in 2018 explored the many possibilities for developing new Exascale computing (a higher scale performance of supercomputing). Exascale supercomputers will be needed in future computing which means high energy efficiency and high cooling efficiency are needed out of these supercomputers to achieve peak performance. The scientists looked to the possibility of "on-chip" cooling, inspired because of the Aquasar supercomputer.
Cooling
The Aquasar supercomputer employs "on-chip" cooling. It uses a unique method that uses micro-channel coolers which are directly attached to the computer's processing units (the main circuits that perform most of the computer's processing) which produce some of the most heat in the computer system. Micro-channels are small channels that have a diameter under 1mm with the warm coolant liquid running through them. Water's high thermal conductivity (the ability to conduct heat) and specific heat capacity (the amount of heat required to raise the temperature of 1 gram by 1 °C) allows the warm water coolant to be set at approximately 60 °C (roughly 140 °F). Because of the high thermal conductivity of water, more heat can be carried by the water away from the processing units. Water has approximately 4,000 times more heat capacity than that of air thus allowing heat transportation to work more efficiently. The high heat capacity allows for the water to absorb a great amount of heat. The water temperature allows the processing units to operate below the maximum temperature of 85 °C (roughly 185 °F).