An EPRI White Paper
DC Power Production, Delivery and Utilization
Figure 9. Blade servers
Blade servers, which consist of units housing multiple, thin, modular electronic circuit boards (the blades) allow for greater processing in less space. These and other high-density equipment are boosting the power needs of data centers.
Headed by the Lawrence Berkeley National Laboratory and im- plimented by EPRI Solutions and Ecos Consulting, the group has obtained funding from the Public Interest Energy Research (PIER), the California Energy Commission (CEC) and the Cali- fornia Institute for Energy Efficiency (CIEE) for a DC demon- stration project at a Sun Microsystems facility in Newark, Cali- fornia. The objectives of the demonstration are to show:
How DC-powered servers and server racks can be built and operated from existing components.
The level of functionality and computing performance when compared to similarly configured and operated servers and racks containing AC power supplies.
Efficiency gains from the elimination of multiple con- version steps in the delivery of DC power to server hardware.
Photo courtesy of IBM
Centralized power architecture
The evolution of centralized power architecture in computers may help standardize and simplify DC power delivery systems serving computer equipment. Separate components within the computer, such as processor, RAM, video card, etc. require different voltages (12 V, 5 V, and even 1.1 V). Computers receive AC power at 120 V and convert it into multiple voltages for these separate internal components. Delivering DC power to today’s computers requires providing DC at each of these different voltages. (See Figure 10.)
With DC power delivery, one standardized DC voltage—likely 12 V, 24 V, or 48 V—can be accepted at a port in the device, and incorporate point-of-load DC-DC converters at the separate com- ponents to adjust the DC voltage as needed.
Figure 10. DC power central architecture for a PC
48V DC bus
Distributed power architecture of electronic equipment (example of a personal computer plugged in to a 48V DC outlet.)