For those thinking of investing in new technologies for data centres, this is a must read document. It describes most technologies and concludes that mainly those related to fundamental issues of cooling and UPS as likely to survive the hype cycle.
(Reproduced by courtesy of Gartner)
As the applications of technologies are changing fast, this work should be updated when possible. It would be useful to explain the outcome differences between ‘on site generation’, ‘low carbon technology’, ‘renewable energy’ and ‘energy efficiency’, and how free cooling affects them. This would be useful to explain the following:
- Only if cogeneration uses biofuel will it be renewable and its relative efficiency will depend on how well does each national grid perform. I would also challenge the statement that it “dramaticallyincreases the energy and carbon efficiency of data centres”.
- CFD and air management are only energy enablers, they do not in their own right save energy.
One observation is that the rotary heat exchanger (Kyoto wheel) is a semi-indirect air system as there is outdoor air (although less) entering the data hall.
Another observation is that “in row cooling” is only one method of physical air containment and that there are many other methods that use air-side and water-side free cooling.
For a legacy data centre with a PUE of around 2, the UPS losses will typically be significantly less (typically 3 to 10 times less) than the energy for refrigeration What makes the difference between a data centre with a PUE of around 2 and one of around 1.25 is mainly down to the intensive use of free-cooling.
The true potential of free-cooling (air side, water-side) is not fully appreciated by the market yet. I will bet that it will move from the trough of disillusionment to the slope of enlightenment once the combination of following is understood:
- The true potential of adiabatic cooling
- Opportunity to use of ASHRAE’s recommended and allowed environmental ranges
- Adequate air containment systems in the data hall
Not only will this enable the PUE to reduce dramatically, but important capital costs are also possible. This will happen due to reducing and eliminating chilled water systems and their associated electrical infrastructure.
This is possible in many cities including Johannesburg, London, Madrid, Mexico DF, Moscow, Munich,
Riyadh and San Francisco. If ASHRAE’s allowed range is used, then this applies to most cities in the world including Barcelona, Beijing, Buenos Aires, Chicago, Houston, Istanbul, Miami, Mumbai, New York, Rome, Sao Paulo, Singapore and Tokyo.
Once we have got the PUEs down to below 1.3-1.4, it is likely that the UPS losses will be more predominant than before.
Gartner predict the surviving technologies to be related to cooling and UPS. I would suggest that the running order of technologies should be:
- Air management – physical containment will enable variable air flow supply and fan energy
savings and also enable
- Increase set points of air and water to improve refrigeration efficiency and
- Maximise free cooling opportunities, followed by
- UPS improvements
Ref: Phelps J., Hype Cycle for Data Center Power and Cooling Technologies, 2010, Gartner Research ID