32 Generators at New DuPont Fabros Facility

DuPont Fabros Technology (DFT) said yesterday that it has completed the second phase of its ACC4 data center in Ashburn, Virginia. The 348,000 square foot facility, which will house servers for Facebook, MySpace and Yahoo, features some of the most extraordinary power infrastructure yet seen in the data center industry. As power usage at data centers continues to grow, the new DuPont Fabros facility may offer a glimpse into the future of infrastructure for premium data centers.

The ACC4 facility has a 36.4 megawatt power feed from Dominion Virginia Power, and is supported by 32 huge 2.25 megawatt diesel generators. That number is correct: 32 generators. The building has four 50,000 gallon tanks of diesel fuel tanks for a total of 200,000 gallons of storage, enough to run the facility on generator power for up to 55 hours during a grid outage. To protect against short-term power outages, ACC4 has 32 rotary power (flywheel) systems that can each produce 1.3 megawatts of output to maintain power until the generators can start.

The 36 megawatt power draw places ACC4 into the upper tier of facility-wide data center power usage. Microsoft has reportedly arranged 48 megawatts of power for its 470,000 square foot data center in Quincy, Washington, while Equinix has lined up 36 megawatts from PSE&G for its 340,000 square foot NJ3 data center, which is nearing completion in Secaucus, New Jersey.

I can’t recall having seen a public report of a data center with more than 32 generators in the 2 megawatt range, although there have been rumors that Google and Microsoft may be in that neighborhood. DuPont Fabros has 18 generators backing its VA3 facility in Reston and 10 more at its VA4 site in Bristow. The multi-tenant design of ACC4 – which is divided into pods that are each supported by a dedicated flywheel and generator – no doubt contributes to the high generator count.

But the trend in generator support clearly seems to be more, not less. Last year we noted that providers were reporting lengthy backlogs on diesel generator orders, in some cases reaching a year or more. Nick Carr recently heard rumors that “Microsoft and Google have locked up a significant portion of Caterpillar’s production for the foreseeable future.”

It looks like DuPont Fabros will be a regular buyer as well. The company holds 13 properties for development as data centers, and just raised nearly $700 million in its IPO. And there’s plenty of room left for expansion in Ashburn. In its description of ACC4, DuPont Fabros notes that “potentially two more exact replicas of ACC4 can be built on site.”

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About the Author

Rich Miller is the founder and editor at large of Data Center Knowledge, and has been reporting on the data center sector since 2000. He has tracked the growing impact of high-density computing on the power and cooling of data centers, and the resulting push for improved energy efficiency in these facilities.


  1. Let's say at best, of that 348,000 square ft, 75% of it will be useable as datacenter floor space. 348,000 * 0.85 = 295,800 square ft of useable floor space. 36000000 watts / 295800 = 121 watts per square ft.. These are 1997 numbers for power density.

  2. The actual raised floor space (which I should have included in the story) is 171,000 square feet. That puts the math closer to 212 watts per square foot facility-wide, with higher densities possible within individual pods.

  3. In that case, they're up to 2004 densities. It seems wasteful to build a modern datacenter without taking current and future hardware growth into account.