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# EPRI Examining Feasibility of Converting IT Systems to Direct Current

July 27, 2006 by Jeff Shepard

With record-setting temperatures and energy usage this summer, the Electric Power Research Institute (EPRI) is examining whether businesses should update their IT systems with more energy efficient systems by eliminating the conversion of direct current (dc) power to alternating current (ac) power.

An increasing number of microprocessor-based electronic devices use dc power, converted from standard ac supply. Other devices, such as variable speed drives for motors, ballasts for fluorescent lights and other equipment can also run on DC power. The migration to dc distribution may extend to residential dwellings as an increasing number of electronic devices and appliances are now available which could run on dc power.

EPRI is working on a series of projects to examine whether eliminating dc-ac converters can be more efficient and practical. At a recent EPRI workshop in Washington D.C., engineers estimated that $115 in electricity savings, per server, per year, could be achieved with dc power delivery. With an estimated 9 million servers now operating in the United States that translates into more than$1 billion in power savings annually, and millions of dollars saved for each large data center.

In an ongoing effort to provide critical information to energy and utility decision makers, EPRI has published DC Power Production, Delivery, and Utilization, a white paper that reviews the potential for increased reliance on dc power systems, as well potential challenges to its adoption. The white paper is available in the EPRI website.

EPRI is working with Lawrence Berkeley National Laboratory and Ecos Consulting to assess the feasibility of a dc-powered demonstration at Sun Microsystems' Newark data center in California. The project hopes to demonstrate how dc-powered servers or server racks can be operated from existing components, providing the same functionality with minimal effort. Efficiency gains from elimination of multiple ac-dc conversion steps will also be measured.

"Data centers are a potential near-term application of dc power delivery, as they have an economic imperative to increase energy efficiency and power reliability," said EPRI's Vice President of Innovation Clark Gellings. "Data centers may house thousands of racks of multiple servers and other computing devices. The density of these servers keeps increasing, wasting power and generating heat with multiple ac to dc conversions. Eliminating ac to dc conversions could reduce inefficiencies in powering the servers, and reduce cooling loads significantly."