5 ms·

The issue is CO2, though, not heat per se. Yes, the two are correlated, but if you use renewables to power your things, it doesn't really matter how much heat y

The issue is CO2, though, not heat per se. Yes, the two are correlated, but if you use renewables to power your things, it doesn't really matter how much heat you generate. Please correct me if I'm wrong.

JumpCrisscross 6y ago
> it doesn't really matter how much heat you generate Doesn’t matter is strong. It won’t in the short term. But as we continue increasing our energy use as a species, the simple thermal problem of waste-heat management will certainly surface.
- StavrosK 6y ago
  Sure, where "doesn't matter" read "is way way less important than CO2 emissions".
- mlyle 6y ago
  If you use renewables, you're using heat that is already around on the planet. As long as you don't change planetary albedo, equilibrium temperature is the same. Of course, heating water locally, etc, can cause its own environmental impacts.
  - bluGill 6y ago
    Not necessarily - if (I think this is true but am not able to prove it) the earth is on a slight negative carbon slope, and renewables reduce that slope we are still making an impact on long term temperature.
  - ithkuil 6y ago
    this! another way to look at it: your solar panels are temporarily "stealing" heat generated by sun rays hitting a surface of equivalent color. When you use electricity to do some work, it will be turned back to heat. so if you want to be 100% "heat neutral", all you have to do is to ensure that for every square meter of solar panels you also paint an proportionate area with a color that reflects the right amount of sunlight to compensate the difference between the color of the solar panel and the area that was there before you installed the solar panel. If you think that's silly (and rightfully so), then perhaps that can sharpen your intuition on how insignificant is the total amount of heat produced by our devices (even if cumulatively they are a big looking number); the total amount of radiation that comes from the sun down to earth is staggering.
    - jacquesm 6y ago
      Solar panels don't work on IR, they work on visible light. IR might be reflected or absorbed. The visible component is absorbed. Whether it would have turned into heat or reflected back in to space is about a 1 in two chance.
      - ithkuil 6y ago
        sorry I don't understand the comment; visible light carries energy too and thus can heat materials it hits. what happens to the IR part of the spectrum is irrelevant and can be captured by the general concept of "color of the object", defined as the spectrum of reflected vs absorbed EM radiation
  - gowld 6y ago
    "Renewable" refers to energy, not just heat. The sun's energy is be used for other purposes than heat, thankfully. Growing a 100 trees and chopping them into lumber is less hot than growing 100 trees and burning them. If all the sun's energy were converted to heat (and not radiated away), we'd be in big trouble. That's what "carbon" pollution is all about -- Carbon dioxide is a greenhouse gas that traps heat. Reducing albedo is one way to increase tempterature, but directly burning stuff is another way.
    - mlyle 6y ago
      I think you missed the point of what I said. When we're talking about powering data centers with renewables, talking about sequestering carbon via lumber is rather orthogonal. The point was, coarsely: using e.g. solar panels only changes the Earth's surface temperature to the extent it changes albedo. (Ignoring second-order effects of concentrating heat and associated effects on radiation, etc.)
  - gpm 6y ago
    This depends on the renewable. Hydro, wind and waves are probably at that ideal except to the extent that they are tidal energy. Solar panels... are literally in the business of making the planetary albedo higher, to the extent that they do so they are introducing thermal energy. Geothermal is in the business of increasing the rate at which heat escapes from underneath the surface, which increases surface temperature. Tidal energy is in the business of extracting energy from the kinetic energy of the moon, which probably increases the temperature of earth (but it's hard to say to what degree). Fusion (if it ever becomes practical, and you count is as renewable) is in the business of releasing potential energy trapped in hydrogen atoms, increasing the temperature. This is particularly problematic because fusion would also enable us to increase our energy usage to the point that direct heating becomes a problem at the same scale as CO2 release currently is. Fission (if you count it) is like fusion. Space based solar (if it ever becomes practical), is increasing the area of the sun captured instead of the albedo, and is directly introducing energy. Etc
- Retric 6y ago
  The similarly extreme version is kind of an interesting comparison, and similarly irrelevant. The 84,000 ppm for 60 minutes is roughly the lethal CO2 concentration. Local CO2 concentration is often several times atmospheric CO2 levels. That’s clearly addressable but I suspect around 8,000 ppm atmospheric we would start to see deaths from this which is achievable from coal deposits. Reaching a fully lethal atmosphere is of course much harder. So, I think you’re right temperature pollution at extreme levels is worse.
- thefifthsetpin 6y ago
  When you say "short term," how long are you talking about?
- fellowmartian 6y ago
  Actually, in the long-term, waste-heat management is the only problem. Every other problem can be geo-engineered away, but we could never geo-engineer away thermodynamics.
trebel 6y ago
Also consider cost (in terms of CO2, resource consumption, etc) of building and maintaining the renewable energy sources. I don't know how this would compare between underwater datacenter, solar panels, wind.
- StavrosK 6y ago
  Building and maintaining the non-renewable energy sources also costs CO2, though.
chriswarbo 6y ago
You're right that renewably-generated waste heat isn't a big deal all-else-being-equal; but all else usually isn't equal, and climate change is a always question of numbers (my favourite example: extracting a barrel of oil from the air/flue using renewable energy and sequestering it long-term, compared to the cost of leaving a barrel's worth of oil where it is in the ground; the latter is free, except for opportunity cost)
- StavrosK 6y ago
  Hmm, wait, why isn't the first one free in terms of CO2?
  - chriswarbo 6y ago
    The first one requires development, construction, installation and maintenance of equipment; it requires explicit effort from many people; it will need to be decommissioned at some point; the storage will have some marginal cost (e.g. containers, drilling holes, etc. depending on the method). These things all cost CO2, unless the economy has already been decarbonised (in which case it wouldn't be needed). More importantly, being "free in terms of CO2" is still an all-else-being-equal perspective. It's focusing on one aspect (CO2 emissions) of one small cog (a CO2 extraction+storage plant). If we look more broadly, each barrel extracted is offsetting less than one barrel being burned elsewhere (since nothing is 100% efficient). CO2 extraction and sequestration is thus a form of power transmission: the work that is required to offset emissions (e.g. from a car) is being performed away from where the emissions are made (although for flue capture this might be quite close!). For example, we can think of these as being roughly equivalent: - A fossil fuel car with solar-powered carbon capture and storage onboard - A fossil fuel car with solar-powered carbon capture and storage in some other location - A solar-charged battery-electric car (+ a little CCS to offset manufacturing emmissions, etc.) These are all solar powered and carbon-neutral (as long as they offset enough). Let's say they each receive a similar amount of solar energy: the first will not get very far, since offsetting is very energy intensive and it needs more fuel to carry the solar+CCS equipment. The second is more efficient, since the fuel doesn't need to move the solar+CCS equipment; it's as if the offboard CCS is transmitting a little extra power to the car. The third will get much further, since the battery and electric motor make much better use of the solar power than the CCS system. The first approach is clearly silly. The second is useful in situations where renewables can't be used directly (e.g. jumbo jet fuel), but is incredibly wasteful and expensive compared to the third. The third approach is best, and should be used as much as possible. If somewhere has an abundance of renewable power (e.g. geothermal in Iceland), then "transmitting" it elsewhere via CCS is much less efficient than, say, laying a high-voltage DC line; or moving high-energy, location-agnostic activities to the region like aluminium smelting or datacenters.
outworlder 6y ago
> but if you use renewables to power your things, it doesn't really matter how much heat you generate. Thermodynamics should really be emphasized in schools. You are getting some amazing responses that are completely ignoring the fact that our renewable energy solutions are not increasing the overall heat in our planet. They are just moving energy around. The only thing that really matters is how are the emissions going to look like when we are manufacturing renewable energy equipment (either new capacity or replacing faulty ones).
- jacquesm 6y ago
  That's faulty. Solar installations change the albedo of the planet. That's not a problem if the fraction is a very small one and it is spread out. But if it is concentrated or relatively large it certainly could have an effect.
  - outworlder 6y ago
    > Solar installations change the albedo of the planet They do. And so does every single thing we build that's exposed to the outside - bulding, cars, even you when you are out and about. The effect is minuscule unless we are turning the planet into Coruscant or this is a gray goo scenario.
    - pbhjpbhj 6y ago
      >The effect is miniscule // The effect of a human on the planet is miniscule, but we're still in the bad state we are. We're looking at covering the planet in solar panels, worth considering how the albedo changes will effect things on a planetary scale.
    - jacquesm 6y ago
      We thought much the same when we introduced the automobile. Plastic for packaging purposes. Freon to help with the Carnot cycle in refrigerators. These things don't matter when you do them once or twice. But when you start doing them on an industrial scale it changes the equation from 'no effect' to 'unknown effect'. And unknown effect might be anything from negligible to planet wide catastrophe. It would be nice to know where we land before taking off. Oceans warming up is a big thing, and local effects can be substantial even if global average change is negligible.

JumpCrisscross 6y ago

> it doesn't really matter how much heat you generate Doesn’t matter is strong. It won’t in the short term. But as we continue increasing our energy use as a species, the simple thermal problem of waste-heat management will certainly surface.

StavrosK 6y ago
Sure, where "doesn't matter" read "is way way less important than CO2 emissions".
mlyle 6y ago
If you use renewables, you're using heat that is already around on the planet. As long as you don't change planetary albedo, equilibrium temperature is the same. Of course, heating water locally, etc, can cause its own environmental impacts.
- bluGill 6y ago
  Not necessarily - if (I think this is true but am not able to prove it) the earth is on a slight negative carbon slope, and renewables reduce that slope we are still making an impact on long term temperature.
- ithkuil 6y ago
  this! another way to look at it: your solar panels are temporarily "stealing" heat generated by sun rays hitting a surface of equivalent color. When you use electricity to do some work, it will be turned back to heat. so if you want to be 100% "heat neutral", all you have to do is to ensure that for every square meter of solar panels you also paint an proportionate area with a color that reflects the right amount of sunlight to compensate the difference between the color of the solar panel and the area that was there before you installed the solar panel. If you think that's silly (and rightfully so), then perhaps that can sharpen your intuition on how insignificant is the total amount of heat produced by our devices (even if cumulatively they are a big looking number); the total amount of radiation that comes from the sun down to earth is staggering.
  - jacquesm 6y ago
    Solar panels don't work on IR, they work on visible light. IR might be reflected or absorbed. The visible component is absorbed. Whether it would have turned into heat or reflected back in to space is about a 1 in two chance.
    - ithkuil 6y ago
      sorry I don't understand the comment; visible light carries energy too and thus can heat materials it hits. what happens to the IR part of the spectrum is irrelevant and can be captured by the general concept of "color of the object", defined as the spectrum of reflected vs absorbed EM radiation
- gowld 6y ago
  "Renewable" refers to energy, not just heat. The sun's energy is be used for other purposes than heat, thankfully. Growing a 100 trees and chopping them into lumber is less hot than growing 100 trees and burning them. If all the sun's energy were converted to heat (and not radiated away), we'd be in big trouble. That's what "carbon" pollution is all about -- Carbon dioxide is a greenhouse gas that traps heat. Reducing albedo is one way to increase tempterature, but directly burning stuff is another way.
  - mlyle 6y ago
    I think you missed the point of what I said. When we're talking about powering data centers with renewables, talking about sequestering carbon via lumber is rather orthogonal. The point was, coarsely: using e.g. solar panels only changes the Earth's surface temperature to the extent it changes albedo. (Ignoring second-order effects of concentrating heat and associated effects on radiation, etc.)
- gpm 6y ago
  This depends on the renewable. Hydro, wind and waves are probably at that ideal except to the extent that they are tidal energy. Solar panels... are literally in the business of making the planetary albedo higher, to the extent that they do so they are introducing thermal energy. Geothermal is in the business of increasing the rate at which heat escapes from underneath the surface, which increases surface temperature. Tidal energy is in the business of extracting energy from the kinetic energy of the moon, which probably increases the temperature of earth (but it's hard to say to what degree). Fusion (if it ever becomes practical, and you count is as renewable) is in the business of releasing potential energy trapped in hydrogen atoms, increasing the temperature. This is particularly problematic because fusion would also enable us to increase our energy usage to the point that direct heating becomes a problem at the same scale as CO2 release currently is. Fission (if you count it) is like fusion. Space based solar (if it ever becomes practical), is increasing the area of the sun captured instead of the albedo, and is directly introducing energy. Etc
Retric 6y ago
The similarly extreme version is kind of an interesting comparison, and similarly irrelevant. The 84,000 ppm for 60 minutes is roughly the lethal CO2 concentration. Local CO2 concentration is often several times atmospheric CO2 levels. That’s clearly addressable but I suspect around 8,000 ppm atmospheric we would start to see deaths from this which is achievable from coal deposits. Reaching a fully lethal atmosphere is of course much harder. So, I think you’re right temperature pollution at extreme levels is worse.
thefifthsetpin 6y ago
When you say "short term," how long are you talking about?
fellowmartian 6y ago
Actually, in the long-term, waste-heat management is the only problem. Every other problem can be geo-engineered away, but we could never geo-engineer away thermodynamics.

trebel 6y ago

Also consider cost (in terms of CO2, resource consumption, etc) of building and maintaining the renewable energy sources. I don't know how this would compare between underwater datacenter, solar panels, wind.

StavrosK 6y ago
Building and maintaining the non-renewable energy sources also costs CO2, though.

chriswarbo 6y ago

You're right that renewably-generated waste heat isn't a big deal all-else-being-equal; but all else usually isn't equal, and climate change is a always question of numbers (my favourite example: extracting a barrel of oil from the air/flue using renewable energy and sequestering it long-term, compared to the cost of leaving a barrel's worth of oil where it is in the ground; the latter is free, except for opportunity cost)

StavrosK 6y ago
Hmm, wait, why isn't the first one free in terms of CO2?
- chriswarbo 6y ago
  The first one requires development, construction, installation and maintenance of equipment; it requires explicit effort from many people; it will need to be decommissioned at some point; the storage will have some marginal cost (e.g. containers, drilling holes, etc. depending on the method). These things all cost CO2, unless the economy has already been decarbonised (in which case it wouldn't be needed). More importantly, being "free in terms of CO2" is still an all-else-being-equal perspective. It's focusing on one aspect (CO2 emissions) of one small cog (a CO2 extraction+storage plant). If we look more broadly, each barrel extracted is offsetting less than one barrel being burned elsewhere (since nothing is 100% efficient). CO2 extraction and sequestration is thus a form of power transmission: the work that is required to offset emissions (e.g. from a car) is being performed away from where the emissions are made (although for flue capture this might be quite close!). For example, we can think of these as being roughly equivalent: - A fossil fuel car with solar-powered carbon capture and storage onboard - A fossil fuel car with solar-powered carbon capture and storage in some other location - A solar-charged battery-electric car (+ a little CCS to offset manufacturing emmissions, etc.) These are all solar powered and carbon-neutral (as long as they offset enough). Let's say they each receive a similar amount of solar energy: the first will not get very far, since offsetting is very energy intensive and it needs more fuel to carry the solar+CCS equipment. The second is more efficient, since the fuel doesn't need to move the solar+CCS equipment; it's as if the offboard CCS is transmitting a little extra power to the car. The third will get much further, since the battery and electric motor make much better use of the solar power than the CCS system. The first approach is clearly silly. The second is useful in situations where renewables can't be used directly (e.g. jumbo jet fuel), but is incredibly wasteful and expensive compared to the third. The third approach is best, and should be used as much as possible. If somewhere has an abundance of renewable power (e.g. geothermal in Iceland), then "transmitting" it elsewhere via CCS is much less efficient than, say, laying a high-voltage DC line; or moving high-energy, location-agnostic activities to the region like aluminium smelting or datacenters.

outworlder 6y ago

> but if you use renewables to power your things, it doesn't really matter how much heat you generate. Thermodynamics should really be emphasized in schools. You are getting some amazing responses that are completely ignoring the fact that our renewable energy solutions are not increasing the overall heat in our planet. They are just moving energy around. The only thing that really matters is how are the emissions going to look like when we are manufacturing renewable energy equipment (either new capacity or replacing faulty ones).

jacquesm 6y ago
That's faulty. Solar installations change the albedo of the planet. That's not a problem if the fraction is a very small one and it is spread out. But if it is concentrated or relatively large it certainly could have an effect.
- outworlder 6y ago
  > Solar installations change the albedo of the planet They do. And so does every single thing we build that's exposed to the outside - bulding, cars, even you when you are out and about. The effect is minuscule unless we are turning the planet into Coruscant or this is a gray goo scenario.
  - pbhjpbhj 6y ago
    >The effect is miniscule // The effect of a human on the planet is miniscule, but we're still in the bad state we are. We're looking at covering the planet in solar panels, worth considering how the albedo changes will effect things on a planetary scale.
  - jacquesm 6y ago
    We thought much the same when we introduced the automobile. Plastic for packaging purposes. Freon to help with the Carnot cycle in refrigerators. These things don't matter when you do them once or twice. But when you start doing them on an industrial scale it changes the equation from 'no effect' to 'unknown effect'. And unknown effect might be anything from negligible to planet wide catastrophe. It would be nice to know where we land before taking off. Oceans warming up is a big thing, and local effects can be substantial even if global average change is negligible.