4 ms·

> Salt water is highly corrosive. To metals. Not so much to plastics. > Isn't marine biology highly sensitive to heat pollution? Isn't land-based biology hig

> Salt water is highly corrosive. To metals. Not so much to plastics. > Isn't marine biology highly sensitive to heat pollution? Isn't land-based biology highly sensitive to heat pollution?

smallnamespace 10y ago
> Isn't land-based biology highly sensitive to heat pollution? No, land-based organisms comparatively have a much, much higher tolerance to temperature swings. Water's high heat capacity and conductivity means that most marine environments have extremely stable temperature ranges (a few degrees one way or other), so most marine species are adapted to live in only that range, and quickly die otherwise. Tropical fish are hard to keep alive precisely for this reason. Air temperature varies much more widely depending on time of day, season, and weather, so terrestrial organisms have all developed extensive strategies for thermoregulation (e.g. mammals, birds). For example, dogs can survive in both arctic and tropical environments. Plus, while heat is naturally dissipated upward, underwater thermal plumes are more likely to affect fish than above-ground plumes would affect birds. FYI, Cornell uses lake water to cool several campus buildings, and they needed to carefully review that the warmer return water wouldn't negatively affect fish [1]. [1] https://energyandsustainability.fs.cornell.edu/util/cooling/production/lsc/eis/fish.cfm https://energyandsustainability.fs.cornell.edu/util/cooling/...
- ouid 10y ago
  Sunlight imparts about a kilowatt per square meter to the surface of the ocean at noon, I'm not exactly sure how to use that information, but it does seem relevant for bounding the problem.
  - afarrell 10y ago
    The specific heat of water is much higher than that of air.
    - klodolph 10y ago
      Right, but the data center heat output will also be measured in (mega)watts.
  - saeranv 10y ago
    This gets a lot lower with differing latitudes and seasonal and daily cloud cover/evening time - closer to 100 W/m2 [1]. So over a day you'd get 2.4 kWh. In comparison an electric space heater uses about 1 kWh of energy in an hour. So how much will 2.4 kWh change the temperature of a cubic meter of water at the ocean surface? Density of water = 1000kg/1m3 so mass = 1000 kg 2.4 kWh = 8640 kJ Heat_Energy = Conductance * Mass * change_in_temp 8640kJ = 4.186 kJ/(kg⋅K) * 1000kg * xC x = 2C So solar heat will change the first meter of water by about 2C over the course of a day. That's a small number b/c solar radiation is not a huge contributer to temperature swings. Instead what will effect the temperature difference is the seasonal change. If we can calculate the heat energy gained or lost due to seasonal extremes and water temp, then we can figure out what the range of acceptable heat energy is for surface water. [1] https://www.withouthotair.com/c6/page_38.shtml https://www.withouthotair.com/c6/page_38.shtml ETA: logic.
walrus01 10y ago
> To metals. Not so much to plastics. I'm guessing you've never experienced the joys of owning a 30 to 40 ft sized, completely non metal (fiberglass hull) sailboat kept in salt water, with all of the great fun of paying to haul it and have the marine growth scaped off, pressure washed, double or triple coat bottom paint re-applied, etc. Just because it's not metal doesn't mean it doesn't attract the category of what the maritime industry lumps together as "marine fouling".
- Xylakant 10y ago
  Though marine fouling is primarily of concern for fiberglass boats because it massively increases drag which admittedly is less of an issue for a datacenter. It's still an issue for the pods as mentioned in the article, but I'd expect it to be less grave than on a boat.
  - baking 10y ago
    Marine fouling of the heat exchangers is probably the biggest technical hurdle.
    - Xylakant 10y ago
      Yes, as well as keeping all kinds of marine life out of there.
  - walrus01 10y ago
    But I require a datacenter with a hull speed of at least 7.5 knots.
    - Xylakant 10y ago
      let me double check the hull speed formula for datacenters.
      - amygdyl 10y ago
        and buoyancy from unvented exhaust from fuel cells ... Edit: I'm very silly, confusing a few thoughts: e.g natural gas > hydrogen conversion in a cell, assuming some storage of the hydrogen, and less dense non salt water from that - all reducing the pod density but hardly exhausts one traps like a submarine vents. What would please my errant mind, growing up by the sea, and startled at effluent pipes i could never believe were far enough out, at low tide, would be biomass conversion fuel cells, attached to sewage pipes otherwise dumping into the sea, but i don't know if treatment renders the mass useless as a energy source. The vision in my head was of container pods popping up, floated from their submersion, for maintenance, kinda being hooked in like exhausted tuna, winched aboard a maintenance vessel once a year, for a data catch... or being fed denser storage or servers... However, what this might do well for, is submerging compute jobs that are expected to run for a long time without much or any external communication. Are there any simulation jobs where enough compute fits inside such a container, so requires mo networking to other containers, and can be retrieved when job complete, to gather results? Would the energy savings make any sense from a cooling pov, if a hypothetical internal power source could last say a year or two?
ch4s3 10y ago
Plastics are good, but you need to have tubes going into the thing, as well as some means of accessing the inside even if you only access it on a ship/land. That means rubber and metal will have to be on the exterior somewhere.
- amygdyl 10y ago
  How submerged does this have to be? Could periscopes aim optical networks, say from 20m below? I'm imagining biomass consuming "creatures", now, with gills to draw the effluent waste from areas around raw sewage outflows that horrified me when little, despite ,my dad rarely corrected about such things, assured me they were legal at the end's distance from shore that i could easily spot nonetheless. My optical networks knowledge is nil, but can simply larger diameter less pure plastic optic fibers transmit sufficient data, compensating by cross section in any way? Assuming one might try to build them strong enough to act also as physical ties, if other limits on movement like chains failed? Can such plastics be made?

> Salt water is highly corrosive. To metals. Not so much to plastics. > Isn't marine biology highly sensitive to heat pollution? Isn't land-based biology highly sensitive to heat pollution?

smallnamespace 10y ago

> Isn't land-based biology highly sensitive to heat pollution? No, land-based organisms comparatively have a much, much higher tolerance to temperature swings. Water's high heat capacity and conductivity means that most marine environments have extremely stable temperature ranges (a few degrees one way or other), so most marine species are adapted to live in only that range, and quickly die otherwise. Tropical fish are hard to keep alive precisely for this reason. Air temperature varies much more widely depending on time of day, season, and weather, so terrestrial organisms have all developed extensive strategies for thermoregulation (e.g. mammals, birds). For example, dogs can survive in both arctic and tropical environments. Plus, while heat is naturally dissipated upward, underwater thermal plumes are more likely to affect fish than above-ground plumes would affect birds. FYI, Cornell uses lake water to cool several campus buildings, and they needed to carefully review that the warmer return water wouldn't negatively affect fish [1]. [1] https://energyandsustainability.fs.cornell.edu/util/cooling/production/lsc/eis/fish.cfm https://energyandsustainability.fs.cornell.edu/util/cooling/...

ouid 10y ago
Sunlight imparts about a kilowatt per square meter to the surface of the ocean at noon, I'm not exactly sure how to use that information, but it does seem relevant for bounding the problem.
- afarrell 10y ago
  The specific heat of water is much higher than that of air.
  - klodolph 10y ago
    Right, but the data center heat output will also be measured in (mega)watts.
- saeranv 10y ago
  This gets a lot lower with differing latitudes and seasonal and daily cloud cover/evening time - closer to 100 W/m2 [1]. So over a day you'd get 2.4 kWh. In comparison an electric space heater uses about 1 kWh of energy in an hour. So how much will 2.4 kWh change the temperature of a cubic meter of water at the ocean surface? Density of water = 1000kg/1m3 so mass = 1000 kg 2.4 kWh = 8640 kJ Heat_Energy = Conductance * Mass * change_in_temp 8640kJ = 4.186 kJ/(kg⋅K) * 1000kg * xC x = 2C So solar heat will change the first meter of water by about 2C over the course of a day. That's a small number b/c solar radiation is not a huge contributer to temperature swings. Instead what will effect the temperature difference is the seasonal change. If we can calculate the heat energy gained or lost due to seasonal extremes and water temp, then we can figure out what the range of acceptable heat energy is for surface water. [1] https://www.withouthotair.com/c6/page_38.shtml https://www.withouthotair.com/c6/page_38.shtml ETA: logic.

walrus01 10y ago

> To metals. Not so much to plastics. I'm guessing you've never experienced the joys of owning a 30 to 40 ft sized, completely non metal (fiberglass hull) sailboat kept in salt water, with all of the great fun of paying to haul it and have the marine growth scaped off, pressure washed, double or triple coat bottom paint re-applied, etc. Just because it's not metal doesn't mean it doesn't attract the category of what the maritime industry lumps together as "marine fouling".

Xylakant 10y ago
Though marine fouling is primarily of concern for fiberglass boats because it massively increases drag which admittedly is less of an issue for a datacenter. It's still an issue for the pods as mentioned in the article, but I'd expect it to be less grave than on a boat.
- baking 10y ago
  Marine fouling of the heat exchangers is probably the biggest technical hurdle.
  - Xylakant 10y ago
    Yes, as well as keeping all kinds of marine life out of there.
- walrus01 10y ago
  But I require a datacenter with a hull speed of at least 7.5 knots.
  - Xylakant 10y ago
    let me double check the hull speed formula for datacenters.
    - amygdyl 10y ago
      and buoyancy from unvented exhaust from fuel cells ... Edit: I'm very silly, confusing a few thoughts: e.g natural gas > hydrogen conversion in a cell, assuming some storage of the hydrogen, and less dense non salt water from that - all reducing the pod density but hardly exhausts one traps like a submarine vents. What would please my errant mind, growing up by the sea, and startled at effluent pipes i could never believe were far enough out, at low tide, would be biomass conversion fuel cells, attached to sewage pipes otherwise dumping into the sea, but i don't know if treatment renders the mass useless as a energy source. The vision in my head was of container pods popping up, floated from their submersion, for maintenance, kinda being hooked in like exhausted tuna, winched aboard a maintenance vessel once a year, for a data catch... or being fed denser storage or servers... However, what this might do well for, is submerging compute jobs that are expected to run for a long time without much or any external communication. Are there any simulation jobs where enough compute fits inside such a container, so requires mo networking to other containers, and can be retrieved when job complete, to gather results? Would the energy savings make any sense from a cooling pov, if a hypothetical internal power source could last say a year or two?

ch4s3 10y ago

Plastics are good, but you need to have tubes going into the thing, as well as some means of accessing the inside even if you only access it on a ship/land. That means rubber and metal will have to be on the exterior somewhere.

amygdyl 10y ago
How submerged does this have to be? Could periscopes aim optical networks, say from 20m below? I'm imagining biomass consuming "creatures", now, with gills to draw the effluent waste from areas around raw sewage outflows that horrified me when little, despite ,my dad rarely corrected about such things, assured me they were legal at the end's distance from shore that i could easily spot nonetheless. My optical networks knowledge is nil, but can simply larger diameter less pure plastic optic fibers transmit sufficient data, compensating by cross section in any way? Assuming one might try to build them strong enough to act also as physical ties, if other limits on movement like chains failed? Can such plastics be made?