DC power? Stick a fork in it

DC power should be a dead issue. That was the word given by Neil Rasmussen, senior vice president of innovation at American Power Conversion during a presentation yesterday afternoon at the company’s annual editor’s event. Rasmussen was referring to the use of DC power as an alternative to AC distribution in data centers. The idea is to use DC distribution to reduce losses, increase efficiency and get runaway power and cooling issues in data centers back under control.

Rasmussen has dismissed the idea before, but much to his consternation, it refuses to go away. “The number one thing that comes up [with customers] is DC power, yet it is one of the least important things you can do to improve efficiency of data centers,” he said.

Efficiency gains in AC infrastructure make a move to DC power unnecessary, Rasmussen argues. “The improvements in existing data center infrastructures have been so radical … that it has essentially made the point moot,” he said. He points to improvements in AC power distribution, UPS and the IT power supplies used in servers and other data center equipment. “The whole power train has only a 5% loss. You’re not going to do any better than that [with DC],” he said.

Then why does interest in DC Power persist? The idea, he says, has been perpetuated by the press, based largely on a report issued a few years ago by William Tschudi at Lawrence Berkeley National Laboratory.

It's true that I've written my share of blogs and stories about DC power, as the links below attest. But there’s another good reason the subject continues to interest data center IT and facilities managers: DC Power has also been kept alive by Rasmussen’s technologist peers, some of whom recently published this peer review of the LBNL study for The Green Grid consortium. That report doesn't exactly dismiss DC power out of hand. Furthermore, DC power distribution designs also make up three of seven possible options in this Green Grid qualitative analysis of distribution options in data centers.

All this is not to say that I disagree with Rasmussen's assessment. In fact, I doubt that DC power will come to pass in data centers, for all the reasons cited here.

Rasmussen’s comments are interesting in the context of APC’s involvement in The Green Grid, which continues to study several DC power alternatives for data centers. APC vice president John Tuccillo is currently the president of Green Grid. While APC cofounder Rasmussen is free to express his opinions, Tuccillo no doubt would like to maintain the posture of being a neutral third party in the debate.

Previous features and columns:

Chilling out with DC Power

DC Power Pros and Cons

Edison’s Revenge

Blogs:

Edison’s Revenge: Will DC Rise Again?

Why DC power is not so hot

UPSes Sexy? Who knew?... Inverter efficiency gains over the past few years have resulted in products that now limit power conversion losses to one sixth of what they were in APC UPSes sold 10 years ago ...