Coming around to using DC power

Many of the electronic devices we use on a daily basis run on DC power including our computers, mobile phones, and video game consoles. As the number of devices running on DC power increases, the problems with running DC devices on an AC grid become more apparent.

Mr. Houseman is talking about any of your electronics that plug in to the wall through one of those AC rectifiers or adapters , (known as "power bricks," "wall warts," etc.) including your smart phone, computer, gaming consoles, many flatscreen TVs, LED lights, and a growing range of other electronic devices.

These digital devices now consume anywhere between 15 and 30 percent  of a typical household's electricity, up from a negligible share just a couple decades ago.

“Within the next 20 years we could definitely see as much as 50 percent of our total [electricity consumption] be made up of DC consumption,” according to Greg Reed, director of the Power & Energy Initiative at the University of Pittsburgh. “It’s accelerating even more than we’d expected,” Reed toldMIT Technology Review  in April 2012.

So what's the big deal? Well, converting from AC to DC power involves wasted energy -- a lot of it.

"Even with improvements in power supplies," Mr. Houseman explains, "many of these devices have a conversion efficiency of no better than 80 percent and some low-end devices have efficiencies as low as 65 percent in converting power."

Presently, data centers - often referred to as server farms, military bases, and universities are all experimenting with DC microgrids, which reduces the energy loss from conversion of AC to DC power and also reduces the heat created by the conversion.

Even today, some large consumers of DC power are already wiring up DC microgrids to more efficiently fuel their needs. The large data centers that run the Internet, cloud computing services, and telecommunications networks are a logical candidate. These "server farms" now consume more than 1.3 percent of all electricity worldwide, according to Tech Review , and that figure is surging.

Since all those servers run internally on DC power, the incoming AC power needs to be converted. "Instead of having power converters on each computer," Tech Review explains, "some companies are installing large centralized converters and distributing 380-volt DC power across their server farms. Japanese telecom giant NTT has four data centers in the Tokyo region operating on DC; last year it completed a DC-based server center in Atsugi City, southwest of Tokyo, that is its first to serve external clients."

An added bonus: reducing AC-DC conversion losses also reduces the waste heat generated by all those power converters, and that further saves on the large amounts of energy used to cool hot-running data centers.

The U.S. military and large campuses such as universities  and hospitals are also experimenting with DC systems, particularly to run critical systems in the case of a failure of the AC power grid.

With the direction that our electronic usage is moving, the future of power could be a split between AC and DC.

To read more, visit The Energy Collective.