4 ms·

If we had energy cheap enough for every human to live at the highest current levels of consumption, wouldn’t we have to do something with the waste heat? Radiat

If we had energy cheap enough for every human to live at the highest current levels of consumption, wouldn’t we have to do something with the waste heat? Radiator fins on space elevators? Or can we send it out into space from the ground?

coldtea 4y ago
We can't even get a stable grid, decent infrastructure, or stocked supermarkets... let alone fancy technology. I would't hold my breat about that going forward.
PeterisP 4y ago
It's not a significant issue. All renewable energy (solar, wind, hydro, biofuels) comes from the sun anyway and the only difference if that sunpower goes into 'waste heat' immediately or gets temporarily used for work before turning into the exact same amount of waste heat. Fossil fuels are releasing energy that was taken from the sun millions of years ago, but the direct heat outcome of burning all that is dwarfed by the greenhouse effect of emitted gasses - small changes to how much Earth radiates into space matter much more than the heat produced by burning that fuel. The same applies for nuclear, which does generate extra waste heat but it is not significant compared to the greenhouse effect.
gizmo686 4y ago
Taking the articles figure of 77,000 kWh per year per person. Lets call it 100,000 (10^5) kWh per year per person and a population of 10 billion (10^10) people, we are looking at 10^15 kWh/year of energy, which is about 10^14 watts. Earth receives about 10^17 watts of solar energy, so we are looking at an increase of about %0.1 of the energy budget. This is ignoring energy coming from non solar sources (there is a lot of geothermnal energy coming from within the planet, but I'm not sure what rate that makes it to the surface). Interestingly, this still overestimates the role of our waste heat for an even simpler reason: much of it was going to be heat anyway. Waste heat generated from fossil fuels is pure extra energy (although that effect is still dwarfed by the greenhouse effect for anything beyond the very local area). Nuclear is effectively net positive on heat as the natural half life of the fuel is far longer then when it is put in a reactor. However, solar energy is by definition part of that 10^17 watts of energy that is going to hit the Earth weather we generated electrons from it or not (Granted, solar panels probably reflect less of that energy back into space). Wind energy is pulling kinetic energy out of the air that would have become heat. Geothermal is taking advantage of heat that was already there (although we accelerate how quickly it reaches the surface). Hydroelectic energy would have become heat once the water finished loosing its potential energy when it reaches sea level.
EdTsft 4y ago
"A total of 173,000 terawatts (trillions of watts) of solar energy strikes the Earth continuously. That's more than 10,000 times the world's total energy use." [1] We have a long way to go before humanity's heat output is anywhere rivalling the heat the Sun dumps on us. Most of our power generation (except nuclear) is just repurposing the Sun's energy anyways, delaying its conversion into heat so that we can extract work from the process. The same heat is generated with or without our power plants. (Fossil fuels delay for so long that the energy release occurs at a much faster rate than it was gathered, but still insignificant compared to the regular solar energy incident on the Earth). [1]: https://news.mit.edu/2011/energy-scale-part3-1026 https://news.mit.edu/2011/energy-scale-part3-1026
- dredmorbius 4y ago
  Yes and no. If GDP is as tightly-coupled to energy use as data suggest, and we presume, say, 4% annual growth rate, then we have a slight issue. 10,000 times is just over 13 doubling periods' worth of growth. And 4% annual growth rate means doubling every 13.3 years, roughly. In which case, humans would cut into that 10,000-fold margin in slightly over 230 years. Which suggests that there are in fact limits to growth.
mcculley 4y ago
I am amused by the optimism of these responses. Nobody is concerned that if we end up with cheap nuclear fusion that humanity won’t use a lot more of it? Would humans stop building resorts in deserts?
- hedora 4y ago
  Deserts are a wonderful place for resorts, assuming it is man made desert (like the Sahara) and infinite energy to desalinate and recycle water in an ecologically sound way. We just aren't to that point yet.
  - mcculley 4y ago
    I am completely a proponent of humanity using cheap energy to elevate our standard of living to ridiculous levels. I’m just wondering what we will do with the waste heat. I cannot believe that we will limit ourselves to current levels of consumption.
  - dredmorbius 4y ago
    I was unaware that the Sahara was man-made.
    - hedora 4y ago
      Yep; we overfarmed the crap out of it in prehistoric times, apparently.
      - dredmorbius 4y ago
        Given that the desert formed > 2 mya and human agriculture originated ~12 kya, this seems unlikely. Modern humans themselves originated only 200 kya. <https://ui.adsabs.harvard.edu/abs/2014Natur.513..401Z https://ui.adsabs.harvard.edu/abs/2014Natur.513..401Z> <https://www.worldhistory.org/article/1886/origins-of-world-agriculture/ https://www.worldhistory.org/article/1886/origins-of-world-a...>

coldtea 4y ago

We can't even get a stable grid, decent infrastructure, or stocked supermarkets... let alone fancy technology. I would't hold my breat about that going forward.

PeterisP 4y ago

It's not a significant issue. All renewable energy (solar, wind, hydro, biofuels) comes from the sun anyway and the only difference if that sunpower goes into 'waste heat' immediately or gets temporarily used for work before turning into the exact same amount of waste heat. Fossil fuels are releasing energy that was taken from the sun millions of years ago, but the direct heat outcome of burning all that is dwarfed by the greenhouse effect of emitted gasses - small changes to how much Earth radiates into space matter much more than the heat produced by burning that fuel. The same applies for nuclear, which does generate extra waste heat but it is not significant compared to the greenhouse effect.

gizmo686 4y ago

Taking the articles figure of 77,000 kWh per year per person. Lets call it 100,000 (10^5) kWh per year per person and a population of 10 billion (10^10) people, we are looking at 10^15 kWh/year of energy, which is about 10^14 watts. Earth receives about 10^17 watts of solar energy, so we are looking at an increase of about %0.1 of the energy budget. This is ignoring energy coming from non solar sources (there is a lot of geothermnal energy coming from within the planet, but I'm not sure what rate that makes it to the surface). Interestingly, this still overestimates the role of our waste heat for an even simpler reason: much of it was going to be heat anyway. Waste heat generated from fossil fuels is pure extra energy (although that effect is still dwarfed by the greenhouse effect for anything beyond the very local area). Nuclear is effectively net positive on heat as the natural half life of the fuel is far longer then when it is put in a reactor. However, solar energy is by definition part of that 10^17 watts of energy that is going to hit the Earth weather we generated electrons from it or not (Granted, solar panels probably reflect less of that energy back into space). Wind energy is pulling kinetic energy out of the air that would have become heat. Geothermal is taking advantage of heat that was already there (although we accelerate how quickly it reaches the surface). Hydroelectic energy would have become heat once the water finished loosing its potential energy when it reaches sea level.

EdTsft 4y ago

"A total of 173,000 terawatts (trillions of watts) of solar energy strikes the Earth continuously. That's more than 10,000 times the world's total energy use." [1] We have a long way to go before humanity's heat output is anywhere rivalling the heat the Sun dumps on us. Most of our power generation (except nuclear) is just repurposing the Sun's energy anyways, delaying its conversion into heat so that we can extract work from the process. The same heat is generated with or without our power plants. (Fossil fuels delay for so long that the energy release occurs at a much faster rate than it was gathered, but still insignificant compared to the regular solar energy incident on the Earth). [1]: https://news.mit.edu/2011/energy-scale-part3-1026 https://news.mit.edu/2011/energy-scale-part3-1026

dredmorbius 4y ago
Yes and no. If GDP is as tightly-coupled to energy use as data suggest, and we presume, say, 4% annual growth rate, then we have a slight issue. 10,000 times is just over 13 doubling periods' worth of growth. And 4% annual growth rate means doubling every 13.3 years, roughly. In which case, humans would cut into that 10,000-fold margin in slightly over 230 years. Which suggests that there are in fact limits to growth.

mcculley 4y ago

I am amused by the optimism of these responses. Nobody is concerned that if we end up with cheap nuclear fusion that humanity won’t use a lot more of it? Would humans stop building resorts in deserts?

hedora 4y ago
Deserts are a wonderful place for resorts, assuming it is man made desert (like the Sahara) and infinite energy to desalinate and recycle water in an ecologically sound way. We just aren't to that point yet.
- mcculley 4y ago
  I am completely a proponent of humanity using cheap energy to elevate our standard of living to ridiculous levels. I’m just wondering what we will do with the waste heat. I cannot believe that we will limit ourselves to current levels of consumption.
- dredmorbius 4y ago
  I was unaware that the Sahara was man-made.
  - hedora 4y ago
    Yep; we overfarmed the crap out of it in prehistoric times, apparently.
    - dredmorbius 4y ago
      Given that the desert formed > 2 mya and human agriculture originated ~12 kya, this seems unlikely. Modern humans themselves originated only 200 kya. <https://ui.adsabs.harvard.edu/abs/2014Natur.513..401Z https://ui.adsabs.harvard.edu/abs/2014Natur.513..401Z> <https://www.worldhistory.org/article/1886/origins-of-world-agriculture/ https://www.worldhistory.org/article/1886/origins-of-world-a...>