Iceland plays its geothermal ace in the high-stakes green data center market. Photo: Verne Global

The amount of data the world stores is on an explosive growth curve. According to research outfit IDC, the digital universe will grow 44 times larger over the course of the decade, thanks to the rise of worldwide obsessions with things like social media and cloud computing. And that means more data centers.

But this data center boom comes at a time of high energy prices and heightened concern about carbon emissions. The days of cramming truck loads of servers into a room and firing up a bunch of industrial air-conditioners to cool them are over.

Data center operators are gaining control of their energy bills and earning green points by increasing data center efficiency, from server processor chips to warehouse-size buildings. There’s no how-to manual on building green data centers. The industry is feeling its way on energy efficiency — and no two data centers are alike.

Out of necessity, the huge Internet players — Google, Facebook, Amazon, Twitter, Yahoo, and Apple — are finding ways to use greener energy and get more out of the energy they use. Google has continued to earn praise for its energy and environmental practices, and Facebook is actually sharing its progress with the rest of the world. This year, it launched the Open Compute Project, encouraging the rest of the industry to exchange technologies and techniques for building efficient data centers.

2011 was a banner year for green data centers, with dozens of state-of-the-art facilities opening for business. Here, Wired takes a look at nine of the more innovative facilities that came online in 2011, rating each by Power Utilization Effectiveness (PUE), the industry standard measure of a facility’s energy-efficiency. PUE is ratio of all electricity a facility consumes to electricity used by the IT equipment it houses.

The ideal — 1.0 — means a facility’s lighting, power, and cooling systems consume no power and its power distribution system is perfectly efficient. Most data centers are in the 2.0 to 3.0 range, meaning ancillary systems and losses consume as much or more energy than the electricity used to run the servers, but the cream of crop have PUE ratings well below this range.

Facebook: Prineville, Oregon

Facebook’s massive complex in the high desert of eastern Oregon makes the most of “free cooling”, meaning using outside air. An aircraft-carrier-size space above the server rooms acts as a giant ventilation duct. An evaporation room uses the site’s dry air for low-power evaporative cooling when outside temperatures are high.

PUE: 1.05 to 1.10

This room in Facebook's Prineville data center puts a chill in the air with minimal exertion. (Photo: Pete Erikson/Wired.com

FedEx: Colorado Springs Colorado

FedEx’s new data center uses cool, dry Rocky Mountain air for “free cooling”. The global shipper expects to use this very efficient cooling 5,000 hours a year, or 57 percent of the time.

PUE: 1.28

Cool, dry air helps give this FedEx data center a Rocky Mountain high level of efficiency. Photo: FedEx

Google: Hamina, Finland

Google converted a 1950s-era papermill into a state-of-the-art data center that uses seawater for cooling. Heat exchangers cool the servers, and the warm wastewater is mixed with seawater before it’s returned to the Gulf of Finland to minimize thermal pollution.

PUE: 1.14*
*average of Google’s 5 MW and larger data centers

Harris Corporation: Harrisonburg, Virginia

This highly redundant, highly secure trusted cloud facility won the Uptime Institute 2011 Green Enterprise IT Audacious Idea award for recycling cooling water to irrigate the data center’s 4.5 acre grounds. A closed-loop condenser cooling system uses ultraviolet light and electrical pulses rather than harsh chemicals to control corrosion, scale and biological contamination.

PUE: 1.36

Hewlett-Packard: Fort Collins, Colorado

HP’s new facility is a testbed for developing green data centers. The Rocky Mountain facility uses “free cooling” and evaporative cooling. It also has thousands of environmental sensors that feed a data analytics system for fine-grained resource management. The plastic sheets above the server racks in the image below prevent cold air fed into the servers from mixing with hot air exhausted from the servers.

PUE: 1.15

Clear plastic walls help this HP data center keep its cool. Photo: HP

IBM: Auckland, New Zealand

IBM’s new down under data center uses environmental monitoring and a power management system that measures power, water and diesel use in real time. The facility uses “free cooling” from outside air and rainwater captured in cooling towers.

PUE: 1.6*
*annual maximum level

Tieto: Espoo, Finland

The European IT services company’s new data center won the Uptime Institute 2011 Green Enterprise IT Beyond the Data Center award for using waste heat to heat 1,500 area homes. The company sited the facility near a cogeneration power plant so that waste heat could be fed into the power company’s district heating network. The data center’s contribution is expected to offset 10,000 tons of carbon dioxide.

PUE: 1.2 to 1.3

Vantage: Santa Clara, California

This data center hosting facility earned LEED Platinum certification, the greenest classification from the US Green Building Council. The energy-efficient facility also conserves water. It was built with low-toxic materials, and 91% of construction waste was diverted from landfills.

PUE: 1.29

This Silicon Valley data center hosting facility looks platinum through green-colored glasses. Photo: Vantage

Verne Global: Reykjanesbaer, Iceland

This data center hosting and co-location facility makes a unique claim: carbon-neutral operations. The facility is powered by geothermal (shown in the image at the top of this story) and hydroelectric energy, which are cheap and abundant in Iceland. It also takes advantage of Iceland’s cool, dry air for year-round “free cooling”.

PUE: 1.2*
*testing phase data