The New York Times reported today that Google has released information on the energy use of their global operations - dominated of course by data centers but including their offices.
I'm surmising now that Google has a data center footprint somewhere in the 225 MW neighborhood; I was off in some analysis I did for a client that pegged them at 300 MW, but I count that as close!
The article attempts to put the load figure into terms that are understandable to laymen, positing that 260 megawatts could serve several hundred thousand homes. That's a spot-on estimate in my experience.
In California, we often use the rule-of-thumb that a MW of capacity is needed to serve about 750 homes. It turns out that this estimate is really based on usage rather than peak demands. The average home in CA uses 750 or so kWh per month, or about 10,000 kWh per year. If you do the math, a MW of generating capacity at 100% load factor would therefore serve 750 homes or so.
But of course utilities do not have flat load curves. The big California utilities have load factors in the 30% range, meaning that you need something on the order of 3 MW of capacity to serve 750 average homes.
For the Google comparison, I fall on the side of using the energy equivalency rather than the demand, though for the best accuracy, we would compare Google's energy use to average home use, or demand to demand.