How do you keep a data center cool in the middle of the desert, in a cost-effective and energy-efficient manner? It turns out that you can use hot water to keep server rooms cool, as eBay's Phoenix data center illustrates.
One of the side effects of running a computer is that it tends to generate heat, which is not such a big deal if you've just got one. But when you scale that upward to running a large number of servers, and on up to rooms full of servers, that heat becomes a big issue. And so most of the facilities use air conditioning to keep their server rooms cool, which is both an extra cost and a higher energy usage for those companies.
But according to Wired, the latest data center for eBay is using hot water to cool their hot servers. They're able to do so because the server rooms themselves are hotter than the water, and the heat from the rooms can be transferred to the water (the second law of thermodynamics in action).
For eBay's Project Mercury, part of the increased efficiency comes through letting their server rooms operate at a bit higher temperatures (as high as 115 degrees F), and the other piece is from then being able to use water which is hot (not heated, just hot, at 87 degrees F), but still cooler than the temperatures in the server rooms, in order to cool the rooms down.
The data center uses two types of cooling, a traditional cooling loop with modular chiller units, and a second cooling loop which uses the hot water to cool:
"A separate cooling loop was designed to use cooling tower water exchanged through a water-side economizer to deliver 30° C hot water cooling to container and rack positions. 30°C is the worst-case scenario on the hottest day of the year based on 50 years of weather data. The cooling system and the servers can use hot water cooling for the entire year by designing both to accommodate a water temperature maximum of 30° C and a maximum data center inlet temperature up to 36° C."
As true in Arizona as it is anywhere, it's not so much the temperature, it's the difference between two temperatures that's important.
Get the details from The Green Grid's case study: Breaking New Ground on Data Center Efficiency