7 ms·

It seems an additional hurdle is anti-fouling. Those barnacles and algae act as an insulator, making the cold-water cooling advantage less and less of an advant

It seems an additional hurdle is anti-fouling. Those barnacles and algae act as an insulator, making the cold-water cooling advantage less and less of an advantage.

mc32 6y ago
Maybe there’s a temp at which it’s too warm for barnacles —question is can the systems within operate at that temperature?
- morsch 6y ago
  The system within would have to operate at a (considerably) higher temperature, since there's a temperature gradient involved and the place where the barnacles are is the coolest part of the whole structure.
OldHand2018 6y ago
Maybe they will release some cooling data that quantifies the effect!
endtime 6y ago
If the surface were that hot, would sea creatures still want to live on it? I have no idea what their range of tolerance is, but I'd assume that they're well adapted for living on relatively cool rocks. And if it's not that hot, then it seems like there's not a cooling problem. (To be clear, I'm speculating without any real knowledge of this subject, and welcome the inevitable corrections.)
- Etheryte 6y ago
  The ocean is host to a very wide number of creatures and bacteria, some live in arctic cold waters, others on volcanic vents, and every range in between. There's a good saying for this, roughly translated, that nature doesn't love an empty spot — if one type of plant or bacteria won't live in an area, someone else will quickly settle in.
  - shuntress 6y ago
    I am familiar with that sentiment expressed through the phrase "nature abhors a vacuum"
    - smaddox 6y ago
      The irony is that this phrase predates the Torricelli experiment, in which he used a glass vial and mercury to produce a vacuum, and the eventual discovery that the vast majority of nature is a vacuum (outside of the atmosphere of planets and stars).
      - freehunter 6y ago
        And if it wasn‘t for gravity, everything inside the atmosphere of planets and stars would be rushing to fill that vacuum. Nature abhors a vacuum, but that‘s only tempered by the fact that there are more powerful forces than vacuums.
        skosch 6y ago
        That's not quite right. Even if there were no gravity or other forces, there would be no incentive for matter to go in one direction vs another, regardless of the distribution of matter around it. Over time you'd get a uniform-ish distribution, but that's a question of statistical mechanics, not one of pressure differences. On earth, matter only rushes to fill vacuums because the surrounding air or water pressure pushes it in.
        jakear 6y ago
        Vacuum doesn’t necessarily mean pressure-vacuum. It roughly means extreme concentration gradient, which is as you’ve described universal.
        xf00 6y ago
        > but that's a question of statistical mechanics, not one of pressure differences. My limited understanding was that 'pressure' is just a simplified way of speaking about statistical mechanics.
- LinuxBender 6y ago
  The best resources for this would be the sites that talk about the marine life around nuclear power plants. I do not have links handy, but those would be good places to start.
- winrid 6y ago
  The surface of this container won't get that hot.
hangonhn 6y ago
Is that really still an issue? From my understanding, it's sort of a solved problem. https://www.youtube.com/watch?v=-AdW030xQB4 https://www.youtube.com/watch?v=-AdW030xQB4
- Hnrobert42 6y ago
  That’s a cool video with interesting information, but I don’t think the conclusion from it that fouling is a solved issue.
  - mojomark 6y ago
    You're correct, as a marine engineer, I can tell you that the biofouling problem is far from solved. To date, copper biocide works best, but is terrible for the environment. A lot of the new coatings are also 'speed-release', meaning the hull must travel a certain speed in the water before the biofouling simply falls off. Obviously for a hull that site stagnant in the water, like Natick, this type of coating won't help. Many people have tried to solve the issue passivly, and even tried mimicking shark skin (tiny chevron-shaped scales) at the microscale to minimized biological growth's ability to "latch" to the material surface. However, I haven't seen any good commercially viable progress in practice. I'm not sure how the MS Natick's cooling system works, but if it's anything like a ship, the heat transfer surface is NOT typically the skin of the hull (although keel coolers are essentially that, but I don't see keel coolers on the Natick hull). Instead, ship cooling systems typically suck in the virtually endless supply of cold seawater, run it through a heat exchanger (often a plate type), generally with a feshwater loop on the other side that runs to hardware to be cooled. The servers would be cooled by this fresh chillwater loop. The above system only works if a.) you have much excess cool seawater than heat infusion (i.e. you're not trying to cool a large server farm in a stationary pond or small lake), and b.) You have means to clean the biofouling that will occur on the seawater side of the heat exchanger if left unabated. The latter, as indicated by reduced cooling capacity, may be why MS needed to stop the project 3 years shy of the objective completion date.
- nomel 6y ago
  I can't imagine a field of these (which I assume is the eventual goal), covered in biocides, would be that great for the environment.
Const-me 6y ago
The container is huge, and the insulation by algae is not that good. Anti-fouling matters for boats because increases energy consumption when it sails. Pretty sure for the datacenter it only contributes to a few degrees C.
deleted 6y ago
[deleted]
sandworm101 6y ago
>> Those barnacles and algae act as an insulator Maybe not. Barnacles probably conduct heat at a similar rate to water. And they create a rougher surface with greater contact area to the surrounding water. And some of them actively filter water, push it around. Perhaps having a layer of barnacles woudl increase cooling.
- morei 6y ago
  The cooling nature of water comes from the high specific heat _and_ the fluid mixing (convection currents, pumped flow, etc). Barnacles and other accretive life forms means that the thermal gradient drops sharply, and hence the heat flow rate drops significantly. Take a comparison is between (say) 25C heatsink in contact with 10C water across a boundary layer that likely on the order of 10mm thick, versus what is effectively a static fluid ~50mm thick followed by the same boundary layer. So the unmixed fluid is going to be ~6x [1] thicker, for a heat flow rate 1/6th the original. And that's assuming that barnacles do in fact conduct as well as water, something that's unlikely (water is ~0.6, human flesh ranges from ~0.2 to ~0.5) [1] Insert a bunch of unstated assumption about the fluid flow rate, salinity, etc etc.
  - ezconnect 6y ago
    This is probably one of the reason they pulled it before the 5 years they are planning. The ambient temperature have increased to a level they think it will cause more server failure.
megablast 6y ago
You can get anti fouling that lasts for 10 years.
javiramos 6y ago
Maybe the vessels could be built with a cleanout mechanism that periodically activates and brushes the outside free of algae?

It seems an additional hurdle is anti-fouling. Those barnacles and algae act as an insulator, making the cold-water cooling advantage less and less of an advantage.

mc32 6y ago

Maybe there’s a temp at which it’s too warm for barnacles —question is can the systems within operate at that temperature?

morsch 6y ago
The system within would have to operate at a (considerably) higher temperature, since there's a temperature gradient involved and the place where the barnacles are is the coolest part of the whole structure.

OldHand2018 6y ago

Maybe they will release some cooling data that quantifies the effect!

endtime 6y ago

If the surface were that hot, would sea creatures still want to live on it? I have no idea what their range of tolerance is, but I'd assume that they're well adapted for living on relatively cool rocks. And if it's not that hot, then it seems like there's not a cooling problem. (To be clear, I'm speculating without any real knowledge of this subject, and welcome the inevitable corrections.)

Etheryte 6y ago
The ocean is host to a very wide number of creatures and bacteria, some live in arctic cold waters, others on volcanic vents, and every range in between. There's a good saying for this, roughly translated, that nature doesn't love an empty spot — if one type of plant or bacteria won't live in an area, someone else will quickly settle in.
- shuntress 6y ago
  I am familiar with that sentiment expressed through the phrase "nature abhors a vacuum"
  - smaddox 6y ago
    The irony is that this phrase predates the Torricelli experiment, in which he used a glass vial and mercury to produce a vacuum, and the eventual discovery that the vast majority of nature is a vacuum (outside of the atmosphere of planets and stars).
    - freehunter 6y ago
      And if it wasn‘t for gravity, everything inside the atmosphere of planets and stars would be rushing to fill that vacuum. Nature abhors a vacuum, but that‘s only tempered by the fact that there are more powerful forces than vacuums.
      - skosch 6y ago
        That's not quite right. Even if there were no gravity or other forces, there would be no incentive for matter to go in one direction vs another, regardless of the distribution of matter around it. Over time you'd get a uniform-ish distribution, but that's a question of statistical mechanics, not one of pressure differences. On earth, matter only rushes to fill vacuums because the surrounding air or water pressure pushes it in.
        jakear 6y ago
        Vacuum doesn’t necessarily mean pressure-vacuum. It roughly means extreme concentration gradient, which is as you’ve described universal.
        xf00 6y ago
        > but that's a question of statistical mechanics, not one of pressure differences. My limited understanding was that 'pressure' is just a simplified way of speaking about statistical mechanics.
LinuxBender 6y ago
The best resources for this would be the sites that talk about the marine life around nuclear power plants. I do not have links handy, but those would be good places to start.
winrid 6y ago
The surface of this container won't get that hot.

hangonhn 6y ago

Is that really still an issue? From my understanding, it's sort of a solved problem. https://www.youtube.com/watch?v=-AdW030xQB4 https://www.youtube.com/watch?v=-AdW030xQB4

Hnrobert42 6y ago
That’s a cool video with interesting information, but I don’t think the conclusion from it that fouling is a solved issue.
- mojomark 6y ago
  You're correct, as a marine engineer, I can tell you that the biofouling problem is far from solved. To date, copper biocide works best, but is terrible for the environment. A lot of the new coatings are also 'speed-release', meaning the hull must travel a certain speed in the water before the biofouling simply falls off. Obviously for a hull that site stagnant in the water, like Natick, this type of coating won't help. Many people have tried to solve the issue passivly, and even tried mimicking shark skin (tiny chevron-shaped scales) at the microscale to minimized biological growth's ability to "latch" to the material surface. However, I haven't seen any good commercially viable progress in practice. I'm not sure how the MS Natick's cooling system works, but if it's anything like a ship, the heat transfer surface is NOT typically the skin of the hull (although keel coolers are essentially that, but I don't see keel coolers on the Natick hull). Instead, ship cooling systems typically suck in the virtually endless supply of cold seawater, run it through a heat exchanger (often a plate type), generally with a feshwater loop on the other side that runs to hardware to be cooled. The servers would be cooled by this fresh chillwater loop. The above system only works if a.) you have much excess cool seawater than heat infusion (i.e. you're not trying to cool a large server farm in a stationary pond or small lake), and b.) You have means to clean the biofouling that will occur on the seawater side of the heat exchanger if left unabated. The latter, as indicated by reduced cooling capacity, may be why MS needed to stop the project 3 years shy of the objective completion date.
nomel 6y ago
I can't imagine a field of these (which I assume is the eventual goal), covered in biocides, would be that great for the environment.

Const-me 6y ago

The container is huge, and the insulation by algae is not that good. Anti-fouling matters for boats because increases energy consumption when it sails. Pretty sure for the datacenter it only contributes to a few degrees C.

deleted 6y ago

[deleted]

sandworm101 6y ago

>> Those barnacles and algae act as an insulator Maybe not. Barnacles probably conduct heat at a similar rate to water. And they create a rougher surface with greater contact area to the surrounding water. And some of them actively filter water, push it around. Perhaps having a layer of barnacles woudl increase cooling.

morei 6y ago
The cooling nature of water comes from the high specific heat _and_ the fluid mixing (convection currents, pumped flow, etc). Barnacles and other accretive life forms means that the thermal gradient drops sharply, and hence the heat flow rate drops significantly. Take a comparison is between (say) 25C heatsink in contact with 10C water across a boundary layer that likely on the order of 10mm thick, versus what is effectively a static fluid ~50mm thick followed by the same boundary layer. So the unmixed fluid is going to be ~6x [1] thicker, for a heat flow rate 1/6th the original. And that's assuming that barnacles do in fact conduct as well as water, something that's unlikely (water is ~0.6, human flesh ranges from ~0.2 to ~0.5) [1] Insert a bunch of unstated assumption about the fluid flow rate, salinity, etc etc.
- ezconnect 6y ago
  This is probably one of the reason they pulled it before the 5 years they are planning. The ambient temperature have increased to a level they think it will cause more server failure.

megablast 6y ago

You can get anti fouling that lasts for 10 years.

javiramos 6y ago

Maybe the vessels could be built with a cleanout mechanism that periodically activates and brushes the outside free of algae?