5 ms·

> The single most important assumption in this paper is that energy consumption will increase by 2% per year. […] How much energy will we consume in 1,000 years

> The single most important assumption in this paper is that energy consumption will increase by 2% per year. […] How much energy will we consume in 1,000 years I keep posting this link here on HN but, once again, it seems very appropriate: > The upshot is that at a 2.3% growth rate (conveniently chosen to represent a 10× increase every century), we would reach boiling temperature in about 400 years. https://dothemath.ucsd.edu/2012/04/economist-meets-physicist/ https://dothemath.ucsd.edu/2012/04/economist-meets-physicist...

casparvitch 3y ago
If HN was reading Murphy the front page would look very different every day
joak 3y ago
This boiling temperature conclusion makes the assumption that we continue using thermal power (steam engines, etc...), where waste heat is around 60%. However photovoltaic and wind does not produce much waste heat. Arguably solar and wind cannot scale 1000x but then you could have non thermal fusion like Helion's https://www.helionenergy.com/technology/ https://www.helionenergy.com/technology/. Btw, thermal power is already showing limits (rivers overheating in summers), we don't have to wait 400 years to see its failure.
- midasuni 3y ago
  Where does the energy go then? EM radiation leaving the planet?
  - joak 3y ago
    Chemical energy. Like the plants, they take sun energy and store it as chemical energy. We could do the same, take CO2 and water and make CH4 and oxygen (electrolysis + Sabatier reaction) and make plastic. Or take ore, aluminum oxide and iron oxide, and "unburn" them releasing again oxygen (we already do that) etc... We mostly use energy to manufacture things. Life takes energy and lowers the entropy of the planet. Why shouldn't humans able to do the same? Any technical reason?
    - AstralStorm 3y ago
      There are limits to doing this, which is why we find it really hard to, say, remove CO2 from the atmosphere. The technical reason is called entropy. Diffuse heat is hard to concentrate and use, much like gas outside of a container.
    - codethief 3y ago
      > Life takes energy and lowers the entropy of the planet. Why shouldn't humans able to do the same? Any technical reason? Reducing entropy necessarily produces waste energy + entropy elsewhere. So the technical reason this cannot be done at the planetary scale is called Second Law of Thermodynamics. Yes, we could try to put all that excess entropy & heat into space but there are limits to that (Stefan-Boltzmann law, among other things).
- codethief 3y ago
  > This boiling temperature conclusion makes the assumption that we continue using thermal power (steam engines, etc...), where waste heat is around 60%. No, it doesn't. The waste heat, at the very end of the day, is always rather close to 100%. I.e. we use all that electric energy we generate to power computer, fridges, and many other machines, all of which – sooner or later – convert that electric energy to heat. (And, well, maybe a bit of chemical binding energy, depending on the application. But then, a few decades later, those products of our work will usually fall apart and/or are being burnt or torn down.) > you could have non thermal fusion like Helion's No, you can't. As the author says: > this statement is independent of technology. Even if we don’t have a name for the energy source yet, as long as it obeys thermodynamics, we cook ourselves with perpetual energy increase. Free free to have a look at his other article (the one he links in the paragraph above) for some more details -> https://dothemath.ucsd.edu/2011/07/galactic-scale-energy/ https://dothemath.ucsd.edu/2011/07/galactic-scale-energy/
  - XorNot 3y ago
    100% of the heat we get from the sun is currently lost as waste heat, by one means or another. So you're not boiling the oceans by any reasonable projection of energy usage increase of solar energy. (yes yes some of it is reflected back into space as non-IR light, but you can also lose IR-emissions back into space without heating the Earth as well).
    - codethief 3y ago
      Most of that incoming heat is reflected / radiated off actually. It doesn't "stay" on Earth. https://en.m.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law https://en.m.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law
      - XorNot 3y ago
        That is literally what I said.
        3y ago
jl2718 3y ago
When the nuclear apocalypse has passed, and the last remaining humans are living underground on mushrooms, somewhere an economist will claim growth using a model updated to include the work done by ants, and somewhere a bureaucrat will update the tax code to collect on it.
istjohn 3y ago
A global cooling system is easily conceivable. The ISS uses radiators to dissipate heat into outer space. We could do the same. We could concentrate heat with heat pumps and pump hot steam, molten salt, or plasma up a space elevator and radiate the heat away. Edit: The link points out that in 1,400 years we'd be using energy at the rate produced by the sun and in 2,500 years at the rate of the entire Milky Way. Even if we solved the heat radiation problem, it seems unlikely we'd be able to obtain fuel for our fusion reactors at a sufficient rate given the speed of light and the density of matter in the universe.
- naikrovek 3y ago
  we can (and do) radiate heat into space already. there's a specific infrared wavelength that passes out of our atmosphere unimpeded. building things which receive sunlight but which emit IR at this wavelength would have a cooling effect, though I don't know to what scale. no need to pump anything up to space, lol. just put hot stuff inside vessels which are painted with a material which radiates heat at this specific wavelength.
  - AstralStorm 3y ago
    Uh, paint doesn't radiate heat not does it convert IR frequencies. (except for very unusual, usually fluorescent materials) It reflects incident IR.
    - naikrovek 3y ago
      not normal paint, no. thanks for nitpicking; always appreciated
- amluto 3y ago
  There’s no free lunch. The sun radiates heat like a blackbody sphere with the surface area of the sun and a surface temperature of 5600K or so. If the Earth were to have a fancy heat pump that radiated the same amount of heat into space, it would need the radiating area times the effective temperature to the fourth power equal to that of the sun. The real killer problem is that your heat pump is subject to the Carnot efficiency of pumping heat to that same temperature. By the most straightforward Second Law calculation, entropy transferred to hot side >= entropy removed from cold side. So Q_hot / T_hot >= Q_cold / T_cold. Q_cold is the heat removed from the pleasant ~300K place where the humans are. At 5600K on the hot side, 18.6 times as much heat needs to be radiated out, so for every bit of useful work done on Earth, at least 17.6 times as much energy is consumed in cooling. If you want the radiator to be only half the surface area of the sun, multiply that by about 16. What future humans really need is a Dyson sphere with absolutely enormous radiating area. :)
nvm0n2 3y ago
That's not a great argument by the physicist, the economist definitely won that debate. The physics guy only seems to realize that though when he wakes up the next day and has calmed down a bit. Although the link is useful for the thermodynamic calculations, there are two major problems with the argument as presented: 1. Right up front the physicist arbitrarily bans space travel. The economist, being an agreeable man who'd probably rather be making smalltalk with a pleasant member of the opposite sex rather than defending his whole profession to a bolshie physicist, accepts this limitation, but he shouldn't have done. Nothing in economics is predicated on a space travel ban. We are already obtaining economic growth from space via satellites and that era has barely got started. None of the physics arguments work if you make the relatively small leap to putting factories, power plants etc on moons, asteroids, space stations or other planets. This doesn't require colonization assuming progress in robotics. 2. Much more seriously, the physicist doesn't understand what growth or wealth mean in an economic context. The economist tries patiently to explain this to him many times, and he just doesn't get it. This is a very common problem when talking about economics because people aren't used to the expansive definition of wealth economists use, so often conflate it with other things like money or (in this case) energy. You can increase wealth indefinitely even with a stable population and stable energy/resource usage. This isn't controversial or weird, it's just part of how wealth is defined. The VR example is one attempt, dessert another attempt to explain this to him, but he just doesn't get it until the next day when he suddenly has an epiphany but decides it wasn't his fault because he personally distinguishes between "growth" and "development". No such distinction is recognized by actual economists for valid reasons. But you don't get to claim there's a problem with economics just because you failed to understand the lingo of the field.
- dTal 3y ago
  If that's "wealth", then "wealth" is worthless. When you have a capped number of humans, and every last one of them is jacked into the Matrix and has everything they could possibly want - what is there left to grow? If the growth in "wealth" doesn't actually reflect an improvement in human experience, then it's a pointless term. Sure you can have two computers trade virtual tokens at an ever-increasing rate until you saturate the network cable, but calling it "wealth" is an exercise in semantic subterfuge. It's like saying economic growth is unbounded because you can always print more money. Eventually it has to bottom out in something real.

casparvitch 3y ago

If HN was reading Murphy the front page would look very different every day

joak 3y ago

This boiling temperature conclusion makes the assumption that we continue using thermal power (steam engines, etc...), where waste heat is around 60%. However photovoltaic and wind does not produce much waste heat. Arguably solar and wind cannot scale 1000x but then you could have non thermal fusion like Helion's https://www.helionenergy.com/technology/ https://www.helionenergy.com/technology/. Btw, thermal power is already showing limits (rivers overheating in summers), we don't have to wait 400 years to see its failure.

midasuni 3y ago
Where does the energy go then? EM radiation leaving the planet?
- joak 3y ago
  Chemical energy. Like the plants, they take sun energy and store it as chemical energy. We could do the same, take CO2 and water and make CH4 and oxygen (electrolysis + Sabatier reaction) and make plastic. Or take ore, aluminum oxide and iron oxide, and "unburn" them releasing again oxygen (we already do that) etc... We mostly use energy to manufacture things. Life takes energy and lowers the entropy of the planet. Why shouldn't humans able to do the same? Any technical reason?
  - AstralStorm 3y ago
    There are limits to doing this, which is why we find it really hard to, say, remove CO2 from the atmosphere. The technical reason is called entropy. Diffuse heat is hard to concentrate and use, much like gas outside of a container.
  - codethief 3y ago
    > Life takes energy and lowers the entropy of the planet. Why shouldn't humans able to do the same? Any technical reason? Reducing entropy necessarily produces waste energy + entropy elsewhere. So the technical reason this cannot be done at the planetary scale is called Second Law of Thermodynamics. Yes, we could try to put all that excess entropy & heat into space but there are limits to that (Stefan-Boltzmann law, among other things).
codethief 3y ago
> This boiling temperature conclusion makes the assumption that we continue using thermal power (steam engines, etc...), where waste heat is around 60%. No, it doesn't. The waste heat, at the very end of the day, is always rather close to 100%. I.e. we use all that electric energy we generate to power computer, fridges, and many other machines, all of which – sooner or later – convert that electric energy to heat. (And, well, maybe a bit of chemical binding energy, depending on the application. But then, a few decades later, those products of our work will usually fall apart and/or are being burnt or torn down.) > you could have non thermal fusion like Helion's No, you can't. As the author says: > this statement is independent of technology. Even if we don’t have a name for the energy source yet, as long as it obeys thermodynamics, we cook ourselves with perpetual energy increase. Free free to have a look at his other article (the one he links in the paragraph above) for some more details -> https://dothemath.ucsd.edu/2011/07/galactic-scale-energy/ https://dothemath.ucsd.edu/2011/07/galactic-scale-energy/
- XorNot 3y ago
  100% of the heat we get from the sun is currently lost as waste heat, by one means or another. So you're not boiling the oceans by any reasonable projection of energy usage increase of solar energy. (yes yes some of it is reflected back into space as non-IR light, but you can also lose IR-emissions back into space without heating the Earth as well).
  - codethief 3y ago
    Most of that incoming heat is reflected / radiated off actually. It doesn't "stay" on Earth. https://en.m.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law https://en.m.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law
    - XorNot 3y ago
      That is literally what I said.
      - 3y ago

jl2718 3y ago

When the nuclear apocalypse has passed, and the last remaining humans are living underground on mushrooms, somewhere an economist will claim growth using a model updated to include the work done by ants, and somewhere a bureaucrat will update the tax code to collect on it.

istjohn 3y ago

A global cooling system is easily conceivable. The ISS uses radiators to dissipate heat into outer space. We could do the same. We could concentrate heat with heat pumps and pump hot steam, molten salt, or plasma up a space elevator and radiate the heat away. Edit: The link points out that in 1,400 years we'd be using energy at the rate produced by the sun and in 2,500 years at the rate of the entire Milky Way. Even if we solved the heat radiation problem, it seems unlikely we'd be able to obtain fuel for our fusion reactors at a sufficient rate given the speed of light and the density of matter in the universe.

naikrovek 3y ago
we can (and do) radiate heat into space already. there's a specific infrared wavelength that passes out of our atmosphere unimpeded. building things which receive sunlight but which emit IR at this wavelength would have a cooling effect, though I don't know to what scale. no need to pump anything up to space, lol. just put hot stuff inside vessels which are painted with a material which radiates heat at this specific wavelength.
- AstralStorm 3y ago
  Uh, paint doesn't radiate heat not does it convert IR frequencies. (except for very unusual, usually fluorescent materials) It reflects incident IR.
  - naikrovek 3y ago
    not normal paint, no. thanks for nitpicking; always appreciated
amluto 3y ago
There’s no free lunch. The sun radiates heat like a blackbody sphere with the surface area of the sun and a surface temperature of 5600K or so. If the Earth were to have a fancy heat pump that radiated the same amount of heat into space, it would need the radiating area times the effective temperature to the fourth power equal to that of the sun. The real killer problem is that your heat pump is subject to the Carnot efficiency of pumping heat to that same temperature. By the most straightforward Second Law calculation, entropy transferred to hot side >= entropy removed from cold side. So Q_hot / T_hot >= Q_cold / T_cold. Q_cold is the heat removed from the pleasant ~300K place where the humans are. At 5600K on the hot side, 18.6 times as much heat needs to be radiated out, so for every bit of useful work done on Earth, at least 17.6 times as much energy is consumed in cooling. If you want the radiator to be only half the surface area of the sun, multiply that by about 16. What future humans really need is a Dyson sphere with absolutely enormous radiating area. :)

nvm0n2 3y ago

That's not a great argument by the physicist, the economist definitely won that debate. The physics guy only seems to realize that though when he wakes up the next day and has calmed down a bit. Although the link is useful for the thermodynamic calculations, there are two major problems with the argument as presented: 1. Right up front the physicist arbitrarily bans space travel. The economist, being an agreeable man who'd probably rather be making smalltalk with a pleasant member of the opposite sex rather than defending his whole profession to a bolshie physicist, accepts this limitation, but he shouldn't have done. Nothing in economics is predicated on a space travel ban. We are already obtaining economic growth from space via satellites and that era has barely got started. None of the physics arguments work if you make the relatively small leap to putting factories, power plants etc on moons, asteroids, space stations or other planets. This doesn't require colonization assuming progress in robotics. 2. Much more seriously, the physicist doesn't understand what growth or wealth mean in an economic context. The economist tries patiently to explain this to him many times, and he just doesn't get it. This is a very common problem when talking about economics because people aren't used to the expansive definition of wealth economists use, so often conflate it with other things like money or (in this case) energy. You can increase wealth indefinitely even with a stable population and stable energy/resource usage. This isn't controversial or weird, it's just part of how wealth is defined. The VR example is one attempt, dessert another attempt to explain this to him, but he just doesn't get it until the next day when he suddenly has an epiphany but decides it wasn't his fault because he personally distinguishes between "growth" and "development". No such distinction is recognized by actual economists for valid reasons. But you don't get to claim there's a problem with economics just because you failed to understand the lingo of the field.

dTal 3y ago
If that's "wealth", then "wealth" is worthless. When you have a capped number of humans, and every last one of them is jacked into the Matrix and has everything they could possibly want - what is there left to grow? If the growth in "wealth" doesn't actually reflect an improvement in human experience, then it's a pointless term. Sure you can have two computers trade virtual tokens at an ever-increasing rate until you saturate the network cable, but calling it "wealth" is an exercise in semantic subterfuge. It's like saying economic growth is unbounded because you can always print more money. Eventually it has to bottom out in something real.