Google has ditched the chillers at its Belgium data center in the name to lower power consumption.
Data Center Knowledge's Rich Miller has a good overview of Google latest data center creation:
Rather than using chillers part-time, the company has eliminated them entirely in its data center near Saint-Ghislain, Belgium, which began operating in late 2008 and also features an on-site water purification facility that allows it to use water from a nearby industrial canal rather than a municipal water utility.
Miller explains that Belgium's climate--66 to 71 degrees on a summer day---allows Google to keep its data center cool on most days of the year. If it's hot Google will power down and use computing resources elsewhere.
The rub: Google can only afford this luxury because it has a vast network. It doesn't sound all that practical for your average enterprise, which would have to watch the weather reports as much as they do their computing loads. However, Google's chillerless data center may be an option for those in cooler climates.