Nikkei Electronics Asia -- February 2009

[Feature] DC Power: From Data Centers to Homes (1)

Direct current (DC) supply, driving equipment with DC power, has been attracting considerable interest lately, and a range of initiatives has been launched in many fields including data centers, offices, plants, shops and the home. DC supply would mean reducing the number of times alternating current (AC)-DC conversion is needed, and the high efficiency would reduce power consumption. As global warming becomes an increasingly hot issue, DC supply has emerged as an extremely effective response. Data centers will begin introducing 300V to 400V high-voltage DC supplies from 2009, and from about 2010 it looks as though 60V or lower DC power will join solar power in homes as well.

Concrete implementations of DC supply to equipment have become more common in recent years (Fig 1). The number of AC-DC conversions can be reduced, providing energy-saving effect in the digital equipment, inverter-equipped products and other DC-powered items. It has been used all along in telephone exchanges and some other systems, but at last implementation efforts are going full-scale. 

One of the most active implementations is in data centers, with an increasing number of cases where DC supplies have been installed as an effective means of slashing power consumption by servers and other information technology (IT) equipment. 

For example, Itochu Techno-Solutions Corp (CTC) of Japan began running a data center with DC supply in October 2008, while multiple server manufacturers are offering DC-power models. In June 2008 the Nippon Telegraph & Telephone (NTT) Group of Japan announced it would implement a phased switch to DC supplies groupwide.

Companies like Hitachi Ltd of Japan and NEC Corp of Japan have also announced construction of DC-power data centers. 

Activity is not limited to data centers, though. In the retail sector, manufacturers have appeared offering DC supply systems for shelf lighting, displays and other applications at prices of Yen10,000 or under. "Convenience stores, shopping centers and other sectors are quite interested," said Satoshi Watanabe, Products Development Department of Kokuyo Store Creation Co Ltd of Japan.

Offices, Factories, Homes

DC power is also being utilized in offices, factories and elsewhere. A source at Takenaka Corp of Japan predicts, "In the next two or three years I think we'll see DC supply systems being installed in factories and the like."

Engineers at manufacturers in the housing, equipment and electrical components industries agree that DC power is coming to the home, too. At CEATEC Japan 2008, held from September 30 to October 4, 2008, Sharp Corp of Japan, TDK Corp of Japan and others revealed concepts for "DC homes," combining solar cells with internal DC supply.

Katsuhiko Machida, Sharp's representative director, chairman & CEO , believes it has enormous potential as a next-generation market, and commented, "Just like LCD televisions became the dominant type in under a decade, I want to establish DC housing in the next ten years."

"Development is under way now, with plans to release to the market in 2010," said Toru Fujioka, director, Advanced Technologies Development Laboratory of Panasonic Electric Works Co Ltd of Japan. An increasing number of manufacturers hope to sell systems to the home market.

Slashing Power Usage

Projects related to DC supply are accelerating in many sectors, including data centers, offices, plants, shops and the home, but why now? One of the reasons is the fact that it could be an effective response to global warming. Japan, for example, has established a target of cutting CO2 emissions to half their present level by 2050, but many people are doubtful that that goal can be attained. It already looks like it will be difficult to meet the target of reducing CO2 emissions in Japan by 6% from fiscal 1990 levels by the year 2012, as defined in the Kyoto Protocol. 

The reason for the doubt is the fact that fiscal 2007 CO2 emissions in Japan rose 8.7% above fiscal 1990 levels. This has meant increased pressure on the power conversion sector, which has such a high CO2 emissions level, and resulted in increased need to slash power consumption.

For example, power consumption by data centers is expected to increase about five times the 2006 level by the year 2025, and operators are getting quite concerned about the electric bill and data center air conditioning (Fig 2). One operator said, "If we keep operating the facility the same way we do now, eventually we'll reach a point where our power receiving capacity, air conditioning capacity and other limits are exceeded. Switching to DC supply is one effective measure."

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