DC Powers Expanding Role

By Jeffrey Burt  |  Posted 2006-08-10 Print this article Print

Tschudi said the energy savings found by the demonstration were significant. At the facility level, they were up to 15 percent, and while theyre still making final calculations, preliminary numbers at the rack level show similar results.

In addition, other factors that would be found in a full data center—such as redundancies—would probably increase those savings, he said.
Other savings would be found in that less heat would be generated, which would lower cooling costs, Symanski said.
In a traditional data center, AC power comes in from an outside power source. Once inside, it goes through multiple conversions back and forth with DC before finally reaching the servers, which run on DC. Its at those conversion points where electricity is lost and heat is generated. At one point in the process, the power is switched to 380v DC power, so keeping it at the stage throughout the entire data center isnt a stretch, Symanski said. Overall, DC power would have fewer moving parts and conversion points, improving reliability and energy efficiency, Tschudi said. DC power already has a role in data centers. Telecommunications companies use it in a lot of their systems, and Rackable Systems offers a line of DC-powered products at the server, rack and facility level. The Milipitas, Calif., company struggled with its second-quarter earnings, seeing its stock price dip almost 40 percent thanks in large part to a decline in its flagship Foundation Series systems for scale-out environments, which does not include its newer Scale Out Series servers, storage or DC offerings. The company has said that as much as 50 percent of Rackable Systems $88.6 million revenue in the second quarter of 2006 was from DC products. In addition, several companies, including Pentadyne in Chatsworth, Calif., and Active Power in Austin, Texas, are also offering flywheel technology as alternatives to UPS (uninterruptible power supply), a battery backup in AC systems. Symanski said customers for several years have been asking about other options for powering data centers. "They either have data centers that are very large and they generate a lot of heat … or they want to get more stuff without creating a heat problem," he said. Gannett is looking to revamp the power infrastructure of its 15,400-square-foot data center in Washington, and has been investigating DC power as an alternative to AC, said Gary Gunnerson, IT architect for Gannett, in McLean, Va., and an eWEEK Corporate Partner. Gunnerson said the proof-of-concept bolstered his belief that DC power could result in savings, though he was unsure whether it would fit into Gannetts plans. Hewlett-Packard looks to nature for the data center of the future. Click here to read more. "So far, Im convinced there are power and infrastructure savings, but Im not convinced that a replacement ROI [return on investment] makes sense," he said. "I had hoped the … experiment could provide tools that allowed some specific data that could drive a data center retrofit evaluation. Im not yet sure we have enough information for that [evaluation]. Green-field installations should carefully consider a DC environment and see if their entire spend makes sense." Finding such a business is a key next step, Tschudi said. Several large companies who viewed the experiment indicated an interest in using DC power in part or all of their data center, so members of the project will try to meet with some of them in the fall to see which would be best suited as an early adopter. In addition, there are other areas around DC distribution systems that need to be studied, including cost implications and reliability issues, he said. The group will meet with the experiments sponsor, the California Energy Commission, to determine whether there is available funding for more studies. Editors Note: This story was updated to include corrected information about Rackable Systems revenue numbers. Check out eWEEK.coms for the latest news, views and analysis on servers, switches and networking protocols for the enterprise and small businesses.


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