Google is highly secretive about the datacenters it builds and won't share details about its power consumption. However, reducing the load of its servers is among one of the company's many green goals.

While Google keeps a tight lid on information about it's datacentres, former Google employee Lloyd Taylor said the company builds modular, scalable datacentres. Australian director of engineering Alan Noble said the efficiency of Google's datacentres was the real "secret sauce" behind the company.

The Mountain View, Calif., headquarters of Google features 1.6 megawatts of solar panels, which generate one-third of its electricity. One of these eight solar rooftops is visible on the right. On a cloudy Friday, a single 135-watt inverter was getting 50 watts.

Although its servers aren't solar-powered, the search giant is considering that option, according to Taliver Heath, Google's "power beagle." Proximity to cheap hydroelectric power was reportedly an attraction for locating a server center in The Dalles, Ore.

In addition to featuring one of the largest US solar plants, Google aims by 2012 to produce 50 megawatts of electricity through "clean" forms of energy. Energy efficiency efforts alone have reduced Google's load by 50 percent within 5 years, said Bill Weihl, Google's energy czar.

And Google is helping to lead efforts to green the IT grid through the Climate Savers Computing Initiative, a collection of nearly 180 enterprises aiming to halve the power consumption of computers by 2010.

Desktop computers currently waste half of the power they use and servers waste one-third, according to Weihl. However, Google's server power supplies achieve as much as 94 percent efficiency, he added.

"This industry spent 30 years selling based on product specs and features," Weihl said. "Energy efficiency was not on the radar."

Weihl explained how prototype photovoltaic panels from Energy Innovations, displayed here in a Google lobby, would use Fresnel lenses and prisms to get 20 watts per square centimeter of solar cell. The panels atop Google's buildings are made by Sharp.

Google.org, the search giant's philanthropic arm, is investing hundreds of millions of dollars toward its goal of making clean energy cheaper than coal.

High-tech data centers make up less than 2 percent of US energy consumption, according to the Environmental Protection Agency. But their growing hunger is posing a challenge to utilities.

California data centers from the Oregon border down to Bakersfield now demand as much as 500 megawatts, which could grow by another 50 to 70 megawatts within the next 18 months, according to Mark Bramfitt, program manager for customer energy efficiency at Pacific Gas & Electric.

Aiming to pool efforts to green the grid, the electricity provider last week brought together efficiency experts from 19 utilities in California, Texas, Vermont, New York, North Carolina, and elsewhere.

The group on Friday toured facilities of several Silicon Valley tech companies making progress to cut energy waste, such as NetApp's data center shown here. Utilities view such efficiency efforts as low-hanging fruit that may be less showy than other options like solar power, but can deliver faster cost savings and greenhouse gas reductions.

Network storage company NetApp used US$1.4 million in Pacific Gas & Electric incentives to green its data center and campus. By April, the Sunnyvale, Calif., company (formerly Network Appliance) will have completed 16 incentive programs through PG&E, according to the company.

"They're definitely the poster child," said Bramfitt of PG&E. "I've never seen anything so pristine."

Bramfitt estimated that PG&E could spend close to US$14 million this year on high-tech, corporate efficiency incentives.

Since 2006, a PG&E program has offered cash to IT companies seeking to reduce their data centers' demands on the grid. Electricity providers in Seattle and British Columbia aim in the coming months to launch programs to help businesses afford energy efficiency overhauls. Similar offers remain rare in North America, which some utilities representatives at last week's summit said they hope to change.

This NetApp data center features clear curtains separating hot and cold aisles of servers and other machines, helping to achieve energy savings of 8 percent, according to David Shroyer, controls engineer. Wireless sensors and software displaying color-coded temperature maps also help the staff to track changes in temperature and electrical usage.

The company is working on a new lab that will house 10 megawatts of equipment on a single floor.

NetApp is one of an increasing number of IT corporations turning to cooling systems that use outside air instead of water, an attractive option for drought-prone regions. Building filtration systems protects digital equipment from floating particulate matter.

Air-side economizers help to keep heating and air conditioning costs low. When indoor and outdoor temperatures are close, such systems bring in and condition outside air rather than recirculating and treating indoor air.

NetApp also has infrastructure for a chilled water system, including rooftop tanks, to support the data center, but it won't be used during most of the year.

NetApps' uninterruptible power supply system was displaying efficiency of nearly 95 percent. The average is closer to 85 percent, according to representatives of utilities touring the company.

NetApp can make its own power using three 375-kilowatt natural gas turbine engines for reducing the load at peak demand. However, the company is saving more by running economizers than it would through cogeneration, Shroyer said.

NetApp also has backup diesel generators.

PG&E worked with Silicon Graphics to choose a cooling system for new software and hardware testing labs that comprise hundreds of CPUs. The Sunnyvale-based maker of server and storage products has downsized its campus from 30 buildings to 2 over the past decade.

Silicon Graphics opted for a cooling system using air instead of water, which would have required towering tanks on the property. As is the case with NetApps nearby, the mild climate is ideal for air cooling systems because the outside and indoor air temperatures are nearly even between September and May.

PG&E provided some US$70,000 of Silicon Graphics' US$200,000 cost to set up an economizer system, the savings could pay for itself within two years. It's the first system of its kind to be developed in tandem with the utility.