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Using the Sea To Cool Your Data Center
1sockchuck writes "We haven't yet seen signs of the Google Navy of seagoing data centers that use the ocean for power and cooling. But data center developers are planning to use sea water air conditioning in a new project on the island nation of Mauritius in the Indian Ocean. Cold water from deep-sea currents would be piped ashore to be used in a heat exchanger for the data center facility. A similar system has been used to replace the chillers at Cornell University, which draws cold water from Lake Cayuga. The Cornell system cost $50 million, but has slashed cooling-related energy usage by 86 percent."
Although this solution is certainly "low power" by no means should it be considered to be entirely green. I work as an engineer on many projects that involve sea water, and when you're using it for a cooling source you typically need to inject some sort of chemical to sterilize the water to keep growths off your heat exchangers (barnacles are sort of a pain in the ass in your exchangers). As a result, using sea water for large scale cooling operations is prohibited in large regions of the United States (specifically the gulf coast) mostly over concerns that the large amounts of warm bleached water will damage the ecosystem. Although, that issue aside, using the ocean as a cooling medium is a great idea, and has been used reliably by power plants for many years.
Toronto already uses cold water cooling for air-conditioning many of its office towers in the downtown core and has for many years. (see: http://www.enwave.com/dlwc.php). Unless winter never visits Canada again, this is cold body is self-replenishing.
I can't image Saltwater not eating the hell out of all the piping.
Yeah, thats the real problem. I hope we discover such metal soon so we can get boats and ships in the oceans too.
A low carbon stainless steel such as the 316 series should be more than sufficient for any piping. Moving parts such as pumps and impellers would be made of titanium for optimum durability and minimum downtime. Lifetime of the pipes is assured by simply adding a small corrosion allowance to the wall thickness (maybe 1/4"), and checking for corrosion once in a while to make sure its not being destroyed faster than you predict. Although that may sound ridiculous, I promise you it is both fairly common and not that hard. Seawater is the lifeblood of many power plants, and it doesn't take a miracle to handle it.
The Cornell project was actually incredibly controversial prior to beginning operation for exactly that reason. Studies since have shown that any detrimental effects are negligible, though, so the controversy has died down in recent years. (I was at Cornell when the system went into operation and for a few years afterward)
The ringing of the division bell has begun... -PF
seawater is the lifeblood of every naval nuclear power plant, and as someone who was in the navy and in charge of the heat exchangers attached to a naval nuclear power plant, i can assure you it is a big deal and a LOT of time and maintenance is put into preventing corrosion and the associated leakage in piping that a heat exchanger utilizes.
In order to have efficient heat exchange between two moving fluids, you need a very thin wall and you need it to be clear of any and all corrosion. This means a lot of time and effort, not too mention chemicals are used.
For a mobile naval vessel, there is no other option, so the cost isn't an issue.
For a land based cooling system, it is an issue because there very well may be less expensive alternatives.
Not too mention the possible ramifications (good and bad) of discharging all of the heated water back into the marine ecology.
Can't you just heat it up to sterilize it?
The total mass of the oceans is about 1.4*10^21 kg. The total mass of the atmosphere is about 5*10^18 kg. That means the oceans weigh about 300 times as much as the atmosphere.
The heat capacity of water is about 4000 J * kg ^ -1 * K ^ -1. The heat capacity of air is about 1 kJ * kg ^ -1 * K ^ -1, or about 1000 J * kg ^ -1 * K ^ -1.
So since there's 300 times as much water as there is air, and the heat capacity of water is 4 times larger, heating up the atmosphere by 1200 degree Celsius would take the same amount of energy as heating up the oceans by 1 degree Celsius. This may not prove or disprove your point, I just started thinking about numbers when you said "raising the temperature of a body of water by a few degrees".
I'd rather you rationally disagree than irrationally agree.
Other than a set up for your gag, I don't see why you call paint a thermal insulator. It does not have to be so. many kinds of coating promote thermal coupling.
One thing that does bother me is dumping waste heat in someone elses backyard for free promotes the inefficient use of energy. that is, I can decrease my cooling costs by using more efficient but more expensive computers which incidentally produce less waste heat, or I could use less expensive inefficient computers and take advantage of public domain cooling, like cayuga lake.
Is Cornell paying a tax to use Cayuga lake as a heat dump? that would help internalize the economic externalities that drive them to consume more electricity because the cooling is free.
likewise for sea water cooling.
This might seem like worry much about a small thing: isn't the cooling resevoir comparatively infinite? the answer is surprising no, not only is it not infinite, it's never going to grow, and we have already saturated it in much or the US and Europe. For example the big limit on Nuclear power plant growth is now availability of cooling. SOme rivers in Tenesee are known to heat up to 80 degrees when the power plants operate a full power in summer.
thus this needs to be publicly regulated now.
Some drink at the fountain of knowledge. Others just gargle.
A low carbon stainless steel such as the 316 series should be more than sufficient for any piping.
Stainless steel is prone to pitting corrosion when exposed to water containing chlorides. 316 series stainless steel is significantly corroded by concentrations of chlorides above 1000ppm (ref). Standard sea water at 3.5% salinity has a chloride concentration of about 20000ppm (ref).
Stainless steel works rather like aluminium when it comes to preventing corrosion; the surface oxidises very rapidly to form a passive coating, protecting the bulk of the metal from oxygen. In water, this only works if (a) the water contains enough oxygen to passivate the metal, and (b) the water won't then dissolve the coating as soon as it forms. In particular, this means that stainless steel is not suitable for things like marine bolts, because under the bolt head the water will quickly lose all its oxygen and you'll get corrosion. It also means you have to be very careful in sea water as the salts can strip off the chromium oxy passive layer.
316 stainless is considered 'marine grade', but only just. In particular, it's unsuitable for warm sea water, as this makes the water vastly more corrosive. So you probably don't want to use it for coolant pipes.
And I haven't even mentioned electrolytic corrosion yet. Sea water is one of the most corrosive environments on the planet, and dealing with corrosion is one of the biggest problems when working with it.
I hope you intended to mod the comment down. What do you think ship's propulsion plant cooling systems and condensers use for cooling water and what do you suppose they are made of? Yes, seawater flows through metal tubes on every ship on the sea. There are saltwater corrosion-resistant alloys, like some bronzes, Monel, and others. Nobody paints the inside of condenser tubes on a nuclear-powered ship, and the primary reason is NOT because paint is a thermal insulator. It's just not necessary and it would be a PITA to do it.
...the future crusty old bastards are already drinking the Kool-Aid.