A preliminary test by the Electric Power Research Institute (EPRI) of a direct-current (DC) power system at a Duke Energy data center in Charlotte, North Carolina, U.S., found that the system uses 15% less electricity than the existing alternating-current (AC) power system.

The U.S. Environmental Protection Agency reported to Congress that data center industry power consumption doubled from 2000 to 2006, and was expected to double again over the next five years. If this trend continues to 2016, then reducing data centers' energy consumption could reduce demand more than 25 billion kWh per year.

“While this is significant news for any company running a data center today, this could be especially critical for the more than 2.5 million smaller data centers across the United States that rely upon inexpensive yet viable ways to reduce costs,” said Curtis Watkins in Duke Energy's technology development group. “If this DC technology was implemented in all those data centers, the impact could be significant.”

For the Duke Energy project, the data center's 480 V AC was converted to 380 V DC and delivered to the equipment racks via a 380 V DC bus. The 15% energy savings provides a good benchmark for the industry, because the 480-V AC system configuration is typical for data centers across the U.S.

For more information, visit www.epri.com.