Google is coming clean about how green it has become. Among other things, the technology giant has revealed that, for all its services, its servers use less energy for a month, per user, than a light bulb that burns for three hours.
But, put together, the company's data centers continually use about 260 million watts, or about 25 percent of what a nuclear power plant generates.
Zero-Carbon Footprint
The company's greenness was detailed for the first time in a posting Thursday on its official Green Blog, and elsewhere. On the blog, Urs Hoelzle, senior vice president for technical infrastructure, noted that, because Google has been a carbon-neutral company since 2007 -- that is, it saves or removes the same amount of carbon emissions as it creates -- even the three hours of a light bulb per user is offset. The resulting carbon footprint of the company is zero.
Previously, Google has been general in discussing its energy use, possibly to avoid releasing competitive information. Now, in an apparent effort to show off its successful conservation and impact-less use of energy, the company is releasing some statistics.
It said its custom-built data centers used only about half the energy of most other centers. About 30 percent of its current electricity use is from renewable sources, including renewable energy already in the grid and renewable energy the company buys directly. That figure is expected to grow to over 35 percent next year.
The company's solar-generated electricity, bike-to-work programs, and other efforts remove the equivalent of about 10,000 metric tons of carbon dioxide from the atmosphere each year. At the Mountain View, Calif., headquarters alone, solar panels generate about 3 million kWh of clean energy annually.
Reusing a Paper Mill
A huge part of Google's energy needs, of course, are its massive data centers. The company has said that it emphasizes four concepts to increase energy efficiency. It accurately measures power usage, keeps the centers warm to reduce cooling costs, designs each element in the data center to operate at optimal efficiency, and cools data centers without chillers.
The company's newest data center, in an old paper mill in Hamina, Finland, uses a variety of innovative techniques to reduce energy use. For instance, raw seawater from the Gulf of Finland uses an existing seawater tunnel, originally built for the paper mill. The seawater is run through heat exchangers, then sent to a "tempering building," where it mixed with more, cooler seawater. It is then returned to the Gulf at a temperature close to the natural one. No compressor-based or refrigerant-based cooling is used.
On Thursday, the company also released a study about the energy savings from using cloud-based services versus housing local servers. It cited data showing that "cloud-based services like Gmail allow organizations of all sizes to reap" advantages of increased efficiency, reduced overhead, and creating a smaller carbon footprint.
Laura DiDio, an analyst with Information Technology Intelligence Corp, said that the greening of data centers "is not a passing fad," because it can be a substantial cost-saving measure. She noted that Dell, IBM, Apple, Microsoft, and HP have also been leaders in this area.
The biggest savers, she said, are virtualization, cloud services and the rise of the remote, mobile workforce, which often mean fewer local power needs.
Gmail's Google Talk widget can now 
