Data centers consume a lot of energy. However, there are a few levers to change that, especially when it comes to cooling, or at least to use the waste heat sensibly.
Throughout Germany, the energy requirements of the server rooms and data centers are said to have been 17 TWh last year. At around 60 percent, cooling the racks accounts for the largest share of the energy overhead in data centers, i.e. the part of the energy that is not required for IT equipment. We spoke to Simon Hinterholzer about the possibilities that are emerging for more energy-efficient data centers – and why they are not yet being implemented.
Simon, the waste heat generated when cooling the large data centers is considerable, but is not used any further. Why not?
This is mainly for economic and organizational reasons. For example, investments in heating networks are required to use the waste heat, which depend, among other things, on how far the heat is transported and to how many consumers it is to be distributed. In addition, in conventional, air-cooled data centers, the use of a heat pump is necessary for most heating applications in order to increase the temperature level. Their operation causes additional costs for electricity.
The classic cooling systems of data centers in particular eat up enormous amounts of energy. What particularly efficient alternatives are there today?
Various developments are already being used to save energy in air-cooled data centers, for example indirect free cooling with a Kyoto wheel or adiabatic evaporative cooling. However, the latter is viewed increasingly critically due to the water requirements in arid regions.
In addition, approaches to cooling IT with liquids have existed for decades in high-performance computing (HPC) and in the private gaming sector. This makes it possible to cool at higher temperatures in order to use the waste heat at the same time. The established solution here is to dissipate the heat by means of a flow-through heat sink on the chips or the entire circuit board. Immersion cooling, in which entire servers are immersed in an electrically non-conductive liquid, which then dissipates the heat, has been the subject of increasing discussion recently.
If the alternatives offer so many advantages, why aren’t they already being used everywhere?
Although the motivation of data center operators to save energy is high due to the relatively high electricity prices in Germany, there are various motives against it from the operator’s point of view. The requirement for enormously high availability of data center services requires a high degree of reliability of all components essential for operation – including the cooling. Data center operators often rent data center space to third parties (colocation). Due to uniform framework agreements (SLA), the operator is often only able to operate conventional cooling.
Thank you for your replies Simon. An article in the cover story of the current iX 9/2022, which also presents energy saving quick wins for IT, provides more information on the cooling alternatives in the data center.
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