There’s a lot of big talk in the data center industry about efficiency. However, despite so many players “talking the talk,” not many are actually “walking the walk.” In fact, a survey of 300 North American corporations conducted by Digital Reality Trust found that, not only has Power Usage Effectiveness (PUE) not improved, it’s gotten worse, rising from 2.8 in 2011 to 2.9 in 2013. While PUE only went up a tenth of a point in that year, this means that corporations are consuming 1.9 extra Watts of energy for every Watt used to run the servers — and, more than likely, the majority of that extra power is being used to cool the data center!
Achieving a low PUE rating can often seem like a daunting task, especially in warmer climates, but we as an industry need to start thinking outside of the traditional data center and focus our efforts on efficiency. I recently presented at Uptime Institute’s Symposium on this topic, offering a case study of how the Interxion team reduced the PUE of our data center campus in Stockholm by implementing seawater cooling.
The Stockholm site opened in 1998 and reached a PUE of 1.95 after five years in operation; our energy bill was approximately $2,562,200 per year! With the help of a close partner, we began bringing in cold seawater (starting at about 6°C, or 42.8°F) and pumping it throughout the site to absorb excess heat and thereby cool the facility; when the water leaves our facility, it is about 24°C, or 75.2°F. Now, our energy bill is nearly a million US dollars less — just $1,576,800 per year.
What makes this project truly unique, though, is that the seawater filters through two of our data centers twice, extending the cooling capabilities of the system and allowing us to drop our energy costs and IT load enough to allow additional customers to colocate within the facility.
Trends like seawater cooling, including other cooling processes that leverage salt water aquifers and deep lake water, carry huge potential to improve overall efficiency in the data center market and realize lower PUEs for organizations, regardless of location. While seawater cooling certainly won’t be feasible in areas that are far from cool water, my hope is that the idea will help data center operators expand their cooling strategies and try new methods!