Intelligent use of heat emissions in data centers of the future

Hannover, Germany, Rüschlikon, Switzerland, 3 March 2008 — At the CeBIT 2008 tradefair scientists from IBM's (NYSE: IBM) Zurich Research Laboratory will present for the first time a pioneering concept of a zero carbon emission data center achieved by the direct reuse of waste heat. The first prototype is not only extremely energy-efficient, but allows three-quarters of the IT operating energy to be redirected to such uses as to heat buildings. This is environmentally friendly and lowers overall operating costs. A powerful new kind of water cooling system embedded on the chip is the basis of this innovation.

Challenges in the IT industry
Energy is an indispensable yet increasingly precious resource. At the same time, it poses a challenge to the IT industry. According to Gartner Group analysts, the information and communications industry accounts for about 2% of global carbon dioxide emissions, which is equal to that generated by air traffic the world over. The US-based Lawrence Berkeley National Laboratory confirms that the worldwide energy consumption of data centers amounts to some 120 billion KWh, roughly equivalent to 14 typical power plants of 1000 megawatts each. This energy is used to operate the data centers around the world that constitute the backbone of our service economy.

And the energy consumption of data centers is increasing. Companies currently spend between 25 and 50% of their total IT budget on data center operations. Indeed, data centers have developed into oversized electrical heating systems. But until now, it has not been possible to channel this energy to serve as a direct supply of heat. Instead, this waste heat is simply dissipated into the environment, meaning that huge potential savings are not being realized.

Technological solution from IBM's Zurich Research Laboratory
Scientists at the IBM Research Laboratory in Zurich now want to change this. At the CeBIT 2008 tradefair in Hannover, Germany, they will present for the first time the pioneering concept of a highly energy-efficient data center that achieves a zero carbon footprint by directly reusing its waste heat. The researchers have designed an innovative energy and cooling circuit, the basis of which is a new kind of water-cooling system that is applied where cooling is needed the most — directly on the chip.

The goal of the zero-emission data center model is to reuse heat generated by the chip for heating buildings, swimming pools etc. or simply for conducting the heat into a municipal heating network. However, the most important requirement for the direct use of heat is that the temperature of the waste heat be above a certain threshold, which, for modern municipal heating networks, is about 50 °C.

To accomplish this, IBM researchers used water, which can conduct heat 4000 times better than air. This alone has an enormous energy-saving potential. But integrating water cooling on the chip, researchers were able to improve the cooling efficiency by several orders of magnitude.

Researchers are now applying this principle to their sophisticated cooling circulation: using hot (45 °C) water, the powerful cooling system is able to cool a chip to the typical operating temperature of 85 °C. This causes the cooling water to reach a temperature of more than 50 °C, and the water can then be used directly to provide heat to a subsequent user. The entire cooling system is a closed circuit in which the cooling water is constantly heated by the chip and then cooled to the required temperature by delivering heat to a subsequent user. This not only eliminates the use of energy-intensive cooling systems, it also substantially reduces the data center's power consumption.

The first prototype of the zero-emission data center, a simplified model of which IBM researchers will present at the CeBIT tradefair, already reuses about three-quarters of the electrical energy needed for IT operation and reallocates it, for example, to heat buildings. This corresponds to a capacity to heat up to 70 homes, in addition to a 40% reduction in energy consumption for a typical 1-MW data center.

Chips: increasingly powerful, but with constantly rising temperatures
The demand for more powerful cooling is the result of an enormous increase in heat flux with each new computer chip generation. Theoretically, today's chips, in operation and without any cooling, would reach a higher surface temperature than the sun (about 6000 °C). In practice, of course, processors could not function for even a fraction of a second without being cooled to below 85 °C. This requires an extremely powerful cooling system, for which air cooling systems are reaching their limits.

In a data center with thousands of processors operating in a small area, powerful cooling systems blow air chilled to 14 °C through perforated floor tiles into the server room. Between 30 and 50% of the power required to run a data center is dedicated to cooling.

The new water-based cooling system is the first approach that makes sense from an ecological and economic perspective and that would allow the meaningful use of waste heat. Water-cooled data centers could become almost twice as profitable as air-cooled centers, including purchase expenses, if new taxes are levied on carbon dioxide emissions. This could offer new perspectives throughout the IT industry, in addition to being good for the environment.