Google's PUE

David Birnbaum davidb at
Wed Oct 1 19:26:48 UTC 2008

I can't comment on the cost to a large data center, but I just finished 
renovating our small data center here in New York City by putting in a 
cogeneration system.  We installed a natural gas microturbine, and are 
recapturing the waste heat to drive an absorption chiller.  The rough 
rule of thumb is 30KW = 10T of chilling.  This type of cogeneration is a 
great match for a communications room because the load is relatively 
stable, and it supports a dual-mode operation, grid-connect and 
grid-standalone, allowing you to run completely detached from local 
utility in the event of an electrical disturbance.  No more recip 
generator backup.

As we were the first to do this in New York City, a lot of the cost and 
delay in the project came in explaining to the city what a microturbine 
was, how it was going to work, demonstrating to the fire department that 
it was safer than 500 gallons of diesel on the roof of a mid-rise, etc.  
The math on the cost savings if you factor in the turbine equipment is 
pretty quick, a couple of years, but if you look at the cost of the 
entire project, 10 years is optimistic.  However, unlike a traditional 
backup, you at least /have/ some sort of cost savings to offset the cap 

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.  :)




Tuc at T-B-O-H.NET wrote:
>> On Oct 1, 2008, at 2:04 PM, Martin Hannigan wrote:
>>>> Personally, I think only a self-owned DC could get that low.  A
>>>> general purpose DC would have too many inefficiencies since someone
>>>> like Equinix must have randomly sized cages, routers and servers,
>>>> custom-built suites, etc.  By owning both sides, GOOG gets a boost.
>>>> But it's still frickin' amazing, IMHO.
>>> I wonder what it cost? :-)
>> What cost to the environment of not doing it?
>> OK, green hat off. :)  Seriously, I doubt GOOG isn't seeing serious  
>> savings from this over time.  If they weren't why would they do it?
> 	They seem to be very environment focused, so I'm sure doing
> anything that isn't is subject to scrutiny from the rest of the industry.
> 	Hopefully it won't come around to bite them. I had read an
> article on "The Planet" going as green as possible, then they had the
> huge outage and I'm sure negated 2-3 times what they had done to that
> point.
> 			Tuc/TBOH

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