5 ms·

There are also fundamental thermodynamic limits that you hit at some point. All production and usage of electricity produces waste heat, it's unavoidable (see C

There are also fundamental thermodynamic limits that you hit at some point. All production and usage of electricity produces waste heat, it's unavoidable (see Carnot). Even neglecting global warming, you can't keep 20th century energy growth going for much more than another century or two before waste heat alone causes catastrophic climate change.

refurb 11y ago
you can't keep 20th century energy growth going for much more than another century or two before waste heat alone causes catastrophic climate change. That seems unlikely to me, but I'd be happy to be proven wrong. I would imagine that all of the waste heat produced through the world's economy is several orders of magnitude lower than the sun. Like less than 0.0001%.
- DennisP 11y ago
  True, and waste heat is a far smaller contribution to warming than greenhouse gases. But exponential growth gets impressive after a while. At 2.3% growth per year, we boil the oceans in about 400 years: http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/ http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-e... Whether this is physically or economically realistic is another matter. I tend to think that long before waste heat is an actual problem, we'll either transition to a stable state or move the growth off planet. (Conveniently, fusion is also great for rockets.)
  - GunboatDiplomat 11y ago
    Well, that assumes we don't move manufacturing processes off planet. Which is more realistic when nigh-unlimited energy (fusion) is available. With that, you can do cool things like launch loops or even a space fountain.
    - DennisP 11y ago
      Hence my last paragraph. But alternative launch systems is a good point.
- namlem 11y ago
  Waste heat could possibly replace natural gas for heating. Eventually that won't be enough, but I'm sure by the time it becomes a problem we'll figure something out.

refurb 11y ago

you can't keep 20th century energy growth going for much more than another century or two before waste heat alone causes catastrophic climate change. That seems unlikely to me, but I'd be happy to be proven wrong. I would imagine that all of the waste heat produced through the world's economy is several orders of magnitude lower than the sun. Like less than 0.0001%.

DennisP 11y ago
True, and waste heat is a far smaller contribution to warming than greenhouse gases. But exponential growth gets impressive after a while. At 2.3% growth per year, we boil the oceans in about 400 years: http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/ http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-e... Whether this is physically or economically realistic is another matter. I tend to think that long before waste heat is an actual problem, we'll either transition to a stable state or move the growth off planet. (Conveniently, fusion is also great for rockets.)
- GunboatDiplomat 11y ago
  Well, that assumes we don't move manufacturing processes off planet. Which is more realistic when nigh-unlimited energy (fusion) is available. With that, you can do cool things like launch loops or even a space fountain.
  - DennisP 11y ago
    Hence my last paragraph. But alternative launch systems is a good point.
namlem 11y ago
Waste heat could possibly replace natural gas for heating. Eventually that won't be enough, but I'm sure by the time it becomes a problem we'll figure something out.