Data Center Handbook

28Using Direct Current Network in Data Centers

Sofia Bergqvist

IBM Corporation, Stockholm, Sweden

28.1 Introduction

The amount of installed power usage in a data center is often in multimegawatts—large data centers can have a power usage of over 500 MW. The total power consumption of the data centers in the world is comparable to that of air traffic. The high energy costs and carbon dioxide emissions resulting from the operation of a data center call for alternative, more efficient solutions for power supply design. One proposed solution to decrease energy usage is to use a direct current (DC) system for all the servers in the data center and thereby reduce the number of conversions between alternating current (AC) and DC.

The DC solution has many advantages over the traditional AC design with regard to efficiency and reliability. Other aspects such as a more efficient integration to renewable energy sources are enabled with the DC technology.

This chapter will focus on the pros and cons of this technology, what studies have been made and what the current market trends are. Some examples from around the world of data centers operating on DC are presented in order to give real-life practical information from operators and data center owners. Furthermore, an introductory section where a background of how our power system has changed over the decades and what comes next can be found in the beginning of this chapter.

The goal is to take all possible parameters into consideration ...