The growth in power use is due to increases in the number of servers being installed and stacked in data centers as demand for computer services accelerates, according to a paper written by Jonathan Koomey, a staff scientist at Lawrence Berkeley National Laboratory who has been advising the U.S. Environmental Protection Agency on energy issues related to data centers.

Using server growth figures based on data from market research firm IDC, Koomey estimated the amount of power consumed annually by servers and associated equipment, such as cooling systems and uninterruptible power supplies. Those technologies consumed 45 billion kilowatt hours nationwide in 2005, he wrote in his paper, which was funded by a grant from Advanced Micro Devices Inc.

Koomey expects power consumption to rise by another 75 percent by 2010. But he said in an interview yesterday that forecasting consumption is a little harder because it's unknown how much demand for new computing services, such as a YouTube, will affect electricity use.

Koomey's paper is a sneak preview of what Congress will hear in June, when the EPA is scheduled to a report on energy use in data centers to lawmakers. Also, with Koomey's help, the agency and a group of major IT vendors are developing an designed to help server buyers compare power consumption from vendor to vendor, especially on low-end x86 systems.

"This is an issue that is not going away," Koomey said. Data center managers "are certainly going to face pressure to reduce the power use of their equipment and improve the efficiency of their servers," he added.