7 ms·

I, for one, believe that continued economic growth needs continued growth in global energy production, and that we will be unable to maintain this growth over t

I, for one, believe that continued economic growth needs continued growth in global energy production, and that we will be unable to maintain this growth over the next century for thermodynamic reasons. This will be the big shit-hits-the-fan moment of the coming years, not climate change or wars. We literally have to throw centuries of economics out the window.

ForHackernews 12y ago
Solar energy is essentially untapped today (relative to output from fossil fuels), and we are in no danger of exhausting the supply of nuclear fuel in the near term.[0] Eventually global energy production will taper off, but I would bet strongly against it being within the next century. [0] http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/ http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium...
- darkmighty 12y ago
  Yea, there is no "thermodynamic reason" for a limited supply of energy. Even if we started expending too much energy in the atmosphere (say if we found an efficient way to fusion), we could pump this excess heat to space, if it would ever come to such an extreme.
  - semi-extrinsic 12y ago
    I see that none of you have heard of Carnot efficiency, or even the second law of thermodynamics. Even if we were to get electric energy from magical pink unicorns that produced no heat, the usage of that energy would produce waste heat. And no, you can't just pump heat into space; if we could that would easily solve global warming.
    - darkmighty 12y ago
      Yes you can... Constructive proof: build a large suspended reflector (mirror), put you power source on it and pump heat from earth to a sphere of any material, which radiates heat into space. No, this of course can't easily solve global warming due to enormous cost it would have and ludicrous efficiency. It's way cheaper to just absorb less heat from the sun (less CO2).
      - semi-extrinsic 12y ago
        Sometimes it's best to do the math before claiming stuff. Now, using thermal radiation from a metal puts your emission spectrum at blackbody radiation around or below 2000 Kelvin, and in that band around 50% of your emitted energy will be absorbed by the atmosphere (thus will not leave earth). Your heat pump going from 293 K to 2000 K will have a laughably low Carnot efficiency (the highest efficiency allowed by thermodynamics): for every Joule of heat you pump from the earth to the sphere, you have to use more than 20 Joules from our magical unicorns. Of these 20 Joules, 10 will be absorbed by the atmosphere and heat the earth. But you have only removed one Joule of heat from the earth. Thus your apparatus is not able to cool the earth, in fact it will be heating the earth by a lot.
        darkmighty 12y ago
        Who says the apparatus has to be in the low atmosphere? What you cite are technical reasons, not thermodynamic. Thermodynamics doesn't disallow the situation, only technical reasons make it difficult. > Sometimes it's best to do the math before claiming stuff > I see that none of you have heard of Carnot efficiency Sometimes it's best to get off your high horse.
        semi-extrinsic 12y ago
        Alright, thermodynamics + not requiring magic (except the unicorns) then. Thermodynamics has everything to do with it; if it were not for the Carnot limit on heat pump efficiency, your proposed scheme for heat removal would work fine. If it were not for the Carnot limit, we would have no problem growing global energy consumption at 2-3% per year (i.e. exponentially) for a hundred more years. So, if you put your apparatus anywhere but in the low atmosphere, how do you expect it to pump heat from the low atmosphere (where the heat is)? I'm not on any high horse, but I'm surprised at how quickly people dismiss this problem as absurd. It's quite obvious if you know some engineering thermodynamics. I think people dismiss it out of cognitive dissonance, since they don't want another unfixable world problem.
        12y ago
amagumori 12y ago
LOL, "thermodynamic reasons". citation needed

ForHackernews 12y ago

Solar energy is essentially untapped today (relative to output from fossil fuels), and we are in no danger of exhausting the supply of nuclear fuel in the near term.[0] Eventually global energy production will taper off, but I would bet strongly against it being within the next century. [0] http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/ http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium...

darkmighty 12y ago
Yea, there is no "thermodynamic reason" for a limited supply of energy. Even if we started expending too much energy in the atmosphere (say if we found an efficient way to fusion), we could pump this excess heat to space, if it would ever come to such an extreme.
- semi-extrinsic 12y ago
  I see that none of you have heard of Carnot efficiency, or even the second law of thermodynamics. Even if we were to get electric energy from magical pink unicorns that produced no heat, the usage of that energy would produce waste heat. And no, you can't just pump heat into space; if we could that would easily solve global warming.
  - darkmighty 12y ago
    Yes you can... Constructive proof: build a large suspended reflector (mirror), put you power source on it and pump heat from earth to a sphere of any material, which radiates heat into space. No, this of course can't easily solve global warming due to enormous cost it would have and ludicrous efficiency. It's way cheaper to just absorb less heat from the sun (less CO2).
    - semi-extrinsic 12y ago
      Sometimes it's best to do the math before claiming stuff. Now, using thermal radiation from a metal puts your emission spectrum at blackbody radiation around or below 2000 Kelvin, and in that band around 50% of your emitted energy will be absorbed by the atmosphere (thus will not leave earth). Your heat pump going from 293 K to 2000 K will have a laughably low Carnot efficiency (the highest efficiency allowed by thermodynamics): for every Joule of heat you pump from the earth to the sphere, you have to use more than 20 Joules from our magical unicorns. Of these 20 Joules, 10 will be absorbed by the atmosphere and heat the earth. But you have only removed one Joule of heat from the earth. Thus your apparatus is not able to cool the earth, in fact it will be heating the earth by a lot.
      - darkmighty 12y ago
        Who says the apparatus has to be in the low atmosphere? What you cite are technical reasons, not thermodynamic. Thermodynamics doesn't disallow the situation, only technical reasons make it difficult. > Sometimes it's best to do the math before claiming stuff > I see that none of you have heard of Carnot efficiency Sometimes it's best to get off your high horse.
        semi-extrinsic 12y ago
        Alright, thermodynamics + not requiring magic (except the unicorns) then. Thermodynamics has everything to do with it; if it were not for the Carnot limit on heat pump efficiency, your proposed scheme for heat removal would work fine. If it were not for the Carnot limit, we would have no problem growing global energy consumption at 2-3% per year (i.e. exponentially) for a hundred more years. So, if you put your apparatus anywhere but in the low atmosphere, how do you expect it to pump heat from the low atmosphere (where the heat is)? I'm not on any high horse, but I'm surprised at how quickly people dismiss this problem as absurd. It's quite obvious if you know some engineering thermodynamics. I think people dismiss it out of cognitive dissonance, since they don't want another unfixable world problem.
        12y ago

amagumori 12y ago

LOL, "thermodynamic reasons". citation needed