Google's PUE

Deepak Jain deepak at ai.net
Wed Oct 1 16:44:49 CDT 2008


> 
> I am going to attempt to determine our PUE, using the methodology 
> described in the Google paper.  One must figure that "in the spirit it 
> was intended" has to factor in the natural gas consumption, otherwise my 
> PUE would be about 0.1.  :)
> 

If you generate energy for your microturbine from a land fill (free 
methane gas) your PUE would be nearly zero. Obviously PUE can be skewed 
and shouldn't be considered as a single metric for anything other than a 
press release.

I would also suggest that Alex shouldn't hold is breath on more details. 
The details provided are interesting, but without context.

(Its like:

"Hi, we filter our river water to evaporate it." But are they 
calculating the cost of all that contaminated material and its disposal? 
The blowdown on their cooling towers would have to be many times more 
hazardous than normal, and may require additional treatment to make it 
safe to release).

Is any math being done to decide whether free river/water-side 
economization is more important (financially/environmentally) than cheap 
energy inputs?

If rather than density, we REDUCE density and build very large foot 
print data centers that can use ambient air (I've heard rumors that MSFT 
is using 85 degree air [cool side] in New Mexico) we could get to PUE 
numbers that were nearly ideal (hot air rises, natural convection, no 
fans, just PDU overhead, etc).

Except where it impacts the bottom line, this all seems more like a 
fashion show than an actual business plan.

Deepak Jain




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