Data Center Knowledge pointed out due to the permiting process for Google's data center in Council Bluffs, Iowa, you can see that there are 38 diesel generators permitted for the facility with a rated power of 2919 bhp (2 megawatt)

Emission Unit(s):

1430 W. South Omaha Bridge Rd.

Council Bluffs, IA 51501

200001

Equipment Location:

None

Emission Point:

Diesel Engine (EU 200001; 2,919 bhp; 137.9 gallons/hr)

Control Equipment:

Also, Data Center Knowledge has pointed out the backlogs for generators and new FCC requirements for cel networks are putting strains on the supply of generators.

"Generator lead time for a nice 2 megawatt diesel engine is now up to a year for one generator," Josh Snowhorn of Terremark said in a panel at the NANOG conference earlier this year. "So we can build all the raised floor we want, and then sit around and wait six months for a generator."

In an effort to keep phone and wireless networks online during natural disasters, the FCC is now requiring telecom and wireless companies to provide backup power for cell sites and remote telecom facilities.

This article is a little old, but I decided to collect information about data centers from Google, Yahoo, and Microsoft.  June 14, 2006 the NYtimes had an article about how hard it is to hide a data center as Google seeks more power.

Hiding in Plain Sight, Google Seeks More Power

Melanie Conner for The New York Times

Google is building two computing centers, top and left, each the size of a football field, in The Dalles, Ore.

Published: June 14, 2006

THE DALLES, Ore., June 8 — On the banks of the windswept Columbia River, Google is working on a secret weapon in its quest to dominate the next generation of Internet computing. But it is hard to keep a secret when it is a computing center as big as two football fields, with twin cooling plants protruding four stories into the sky.

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The New York Times

The complex, sprawling like an information-age factory, heralds a substantial expansion of a worldwide computing network handling billions of search queries a day and a growing repertory of other Internet services.

And odd as it may seem, the barren desert land surrounding the Columbia along the Oregon-Washington border — at the intersection of cheap electricity and readily accessible data networking — is the backdrop for a multibillion-dollar face-off among Google, Microsoft and Yahoo that will determine dominance in the online world in the years ahead.

Microsoft and Yahoo have announced that they are building big data centers upstream in Wenatchee and Quincy, Wash., 130 miles to the north. But it is a race in which they are playing catch-up. Google remains far ahead in the global data-center race, and the scale of its complex here is evidence of its extraordinary ambition.