5. Containers don't make a data center greener

Microsoft has not-so-subtly tried to portray its new data centers as being exemplars of green computing. In San Antonio, the site of an upcoming 470,000-square-foot data center, construction workers built around an old live oak tree on the 44-acre site, even putting up concrete barriers to help protect it according to the local newspaper. It also plans to use recycled gray water in the data center and install the most efficient hardware, power and cooling systems.

Apart from preserving old-growth oak trees, Microsoft is doing many of the same things at its Chicago data center. Another thing about locating in the Windy City is that it is considered the most energy-efficient US city in which to locate a data center.

Indeed, Microsoft said late last year that being in Chicago will enable it to use "all sorts of cold-air cooling options in the winter months," a process known as airside economization.

An airside economizer, explained Svenkeson, is a fancy term for "cutting a hole in the wall and putting in a big fan to suck in the cold air." Ninety per cent more efficient than air conditioning, airside economizers sound like a miracle of Mother Nature, right?

Except that they aren't. For one, they don't work -- or work well, anyway -- during the winter, when air temperature is below freezing. Letting that cold, dry air simply blow in would immediately lead to a huge buildup of static electricity, which is lethal to servers, Svenkeson said.

To keep the humidity at the 30 per cent minimum of most data centers, water would need to be added to the air as it blows in. But that requires exorbitant amounts of energy and can create a huge condensation problem if done wrong.

"You'll quickly have an ice-side economizer," Svenkeson quipped.

Airside economizers actually work better in warmer climates, or in places such as the American Southwest where temperatures drop quickly (but not below zero) at night, Svenkeson said. Or they can work in office environments, where maintaining a minimum humidity is easier because of the workers inside and also less vital.

A less risky solution is using an air conditioning system that can be transformed during the winter into a so-called closed-loop liquid cooling system. This process essentially involved exposing coolant-bearing pipes to the hot air inside the data center. The coolant absorbs the heat and expands, rushing through the pipes to the outside of the building. There, it cools, shrinks and flows back inside, where it repeats the process.

While closed-loop systems are "wickedly efficient," according to Biggs, they still take a lot of energy to work. "There's no free lunch. The laws of physics haven't been repealed."

Even with cutting-edge cooling systems, it still takes a watt of electricity to a cool a server for every watt spent to power it, estimated Svenkeson.

"It's quite astonishing the amount of energy you need," Svenkeson said.

Or as Emcor's Baker put it, "With every 19-inch rack, you're running something like 40,000 watts. How hot is that? Go and turn your oven on."

Manos acknowledged that Microsoft's initial plan to use only air-side economizers, especially during the winter, was overly optimistic. As a result, the Chicago data center will use both air and liquid cooling. "We're optimizing for both extremes," he said.

Manos wouldn't go into details, except to say "an entire organization of research and engineering people" is working on cooling and power issues. "I'm not sure if we're doing anything more revolutionary in this space, but a lot of the problems have been solved."

And he emphasized that with the cost of power making up the vast majority of the ongoing cost of its data center operations, Microsoft has every incentive to make sure they are as energy-efficient as possible.

But with Microsoft building three electrical substations on-site generating a total of 198 megawatts, or enough to power almost 200,000 homes, green becomes a relative term, others say.

"People talk about making data centers green. There's nothing green about them. They drink electricity and belch heat," Biggs said. "Doing this in pods is not going to turn this into a miracle."