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Google's Chiller-Less Data Center
1sockchuck writes "Google has begun operating a data center in Belgium that has no chillers to support its cooling systems, which will improve energy efficiency but make weather forecasting a larger factor in its network management. With power use climbing, many data centers are using free cooling to reduce their reliance on power-hungry chillers. By foregoing chillers entirely, Google will need to reroute workloads if the weather in Belgium gets too warm. The facility also has its own water treatment plant so it doesn't need to use potable water from a local utility."
I don't know about natural lakes but man made ponds have been used for just that purpose.
The ancient Persians had a passively cooled refrigerator called the yakhchal which "often contained a system of windcatchers that could easily bring temperatures inside the space down to frigid levels in summer days."
Perhaps the Google datacenter could employ some variation of their technique.
When things get complex, multiply by the complex conjugate.
They do! Well... not Superior, but Lake Ontario.
Toronto has a rather large system that uses deep, cool water as a heat sink.
Enwave is the company that provides this service.
52 52'23" W 47 32'07" N
They already do that:
http://en.wikipedia.org/wiki/Deep_lake_water_cooling
http://en.wikipedia.org/wiki/Geothermal_heating
If you have chilled water, you have a chiller, which means you have compressors. Process water or ground source water usually is not cold enough to be an effective cooling medium. You want a high delta T between the entering air temp and the entering water temp to induce heat transfer. Closed loop ground source water is extremely (prohibitively) expensive and open loop is quite a maintenance hassle due to water treatment. High efficiency chillers paired with evaporative cooled water towers with economizer capability is very efficient and reliable. Usually you can get down to around 0.5kW per ton with high efficiency chillers at full load and with multiple staged compressors you can do even better with part load conditions. The cooling towers are usually pretty low with around 0.05 to 0.15kW per ton. Use VFD's on the secondary pumps and cooling tower fans, and you can get cooling in at 0.75kW per ton for the whole plant at peak and even lower and part load conditions (95% of the time).
I just designed a data center for a large Big Ten univeristy and there were no large air handlers involved at all. The system had two 400-ton chillers with the chilled water piped directly to rack mount APC fan coils. Without "green" being the basis of design, the chiller system still operates right at about 1kW/ton.
I'm not not licking toads.
A ton is a measure of the amount of heat transferred. See this for more details. It's also worth noting how much of the heat transfer is done by way of allowing the water in the system to evaporate.
"Again using rules of thumb, you can assume that 80% of the electrical power delivered to the computers will be dissipated as heat."
? 100% of the electrical power delivered to the computer is dissipated as heat. It's the law. It will be far less than the nameplate power (that electrical uses), and perhaps 80% of what is delivered to the building (after transformer, UPS, and PDUs), but it all ends up as heat (unless you're splitting hairs about the acoustical energy emissions and velocity pressure in the exhaust, which is small and quickly converted to heat).
The units were mounted on the roof, but were packaged AAON 2 x LL210 chillers (and a full 400 ton backup) with no exposed exterior piping. Glycol reduces the specific heat of the fluid and increases the specific gravity, so it can move less heat and takes more power to move. I only add glycol to the system if freezing is an issue.
I'm not not licking toads.
Cornell University actually did this exact thing to cool a good chunk of the campus. It's called lake source cooling. While there will of course be some environmental impact, the energy usage is 20% of normal chillers and thus is, I'm sure, an environmental net gain.