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The article accounts for this in average earth temperature. The earth’s surface would be hotter than the sun in 1000 years, and would generally be uncomfortabl

by lumost 4y ago

The article accounts for this in average earth temperature. The earth’s surface would be hotter than the sun in 1000 years, and would generally be uncomfortable after 200. The only way around that would be a substantial change in the thermodynamic efficiency of our energy use and/or a non radiative means of disposing of heat. Granted, if we did have the equivalent energy of a sun - we are unlikely to be spending it all on earth. Escaping earths gravity would be a trivial expense.

whatshisface 4y ago
That thermodynamic argument was the least convincing part. If you wanted to, you could beam your power plant's infrared radiation towards space, or put the plant itself in space and have it beam its waste heat away from the planet. The idea that heat dissipation is limited by the black body radiation of the Earth assumes that your house is part of the power plant's radiator, which itself implies that you will be living in a power plant's radiator. :-)
- betwixthewires 4y ago
  That's because you don't understand thermodynamics. You can't just put the power plant in space and keep the heat from generating the power away from the earth, because the heat gets created where the power is used to perform work. You have to avoid consuming any of that power on the earth entirely. And you can't just beam the waste heat from every process away from the surface of the earth, that violates the second law of thermodynamics. The heat exists because the energy performed work, you are keeping the energy organized by beaming it in any direction, so it is not waste heat, it is direct infrared from the energy you've produced. You can only do this by not actually using the energy for work. This makes the whole exercise of even producing the energy pointless. I think the biggest hole in the argument is the jump to 100% efficiency. we don't consume mor energy because we feel like it, we consume it because we need it, and a factor of 5 increase in efficiency would equate to a factor of 5 decrease in production of energy resources.
  - whatshisface 4y ago
    >you are keeping the energy organized by beaming it in any direction I am afraid it is you who misunderstand thermodynamics, my friend. :-) Entropy is a matter of degree, and as long as the beam leaving the Earth is less ordered than the beam coming down, it can work. For example, imagine a hot nail on the moon suspended a few inches above a mirror. The heat will radiate into space and the moon won't get hotter.
    - betwixthewires 4y ago
      Yes, but that energy cannot be used for work on the moon...
      - taneq 4y ago
        Presumably the work is what heated the nail up in the first place…
        betwixthewires 4y ago
        Yes, and if that work was done on the moon, the nail wouldn't be the only thing that was hot.
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  - blueblimp 4y ago
    > And you can't just beam the waste heat from every process away from the surface of the earth, that violates the second law of thermodynamics. Surely this can't be right, because if it were, air conditioning (the normal everyday kind) would be impossible, right? What we're talking about here is loosely analogous to air conditioning the entire Earth (with the heat being sent to space rather than the outside air). Sounds like a hard engineering problem, but not impossible.
- mbbutler 4y ago
  But the energy transported to Earth from your space power plant still creates waste heat when it is used to do work (and also when it is transported to earth). You cannot beat the second law.
- mgsouth 4y ago
  Let us, per the article's title, do the math... * Total energy consumption = 10^26 watts (hope the caret comes through HN formatting) * Assume some magical generation and transport mechanisms which don't involve energy gradiants (avoiding pesky thermodynamic realities), and are 99.9% efficient. * Total waste energy is 10^23 watts. * Radiators are on Earth, and we dedicate 1/2 of the entire surface area (not just land) to radiators. Earth has about 5.1 x 10^8 km^2, so say 2.5 x 10^14 sq. meters. * Radiators for the waste heat would be dumping 10^23 W / 2.5 x 10^14 m^2 = 4 x 10^8 watts per square meter. That's 400 megawatts. Per square meter. * That's a black-body temperature of 9,165 K (the Sun's surface is 5,772 K). Peak wavelength is 316 nm. So half the Earth's surface is a glowing UV light pointed at the sky. I don't think we'd have to worry about the ozone layer disappearing. (A very bright, inefficient UV lamp--plenty of infrared, hard UV, and soft X-rays to go around!) * OK, so put the power plants in geostationary orbit. Say 1 million power stations, each with radiators 1 square kilometer. * 1e6 stations * 1e9 square meters = 1e15 sq meters. * So, that's only 1e8 watts/meter! Hmm. Still 6,480 K, but peak is blue-violet rather than UV. Still lots of UV and infrared, but it's space, who cares. Just don't cross the beams (ha ha, meaning no deep-space traffic). And mind the Moon! (Wouldn't want to give anbody on earth a reflected sunburn). * The radiation pressure from the waste engery for one power stations would be about 730 kN (160,000 pounds). Would need counter-balanced beams. * Geostationary orbit is about 26,000 miles. The surface area of a sphere that big is 2e16 square meters. So about 1/20th of the sky would be covered with powerplant radiators. And this is just for the hypothetical 0.1% waste energy. Multiply all of the above by 1,000 for the actual used energy. So you'd have half the Earth's surface as power receivers slurping up 400 gigawatts/square meter of X-rays and hard UV. Each power station would see a force of 739 mega-newtons; you'd have to have a counter-balancing beam pointing away from Earth. And then you'd need to radiate away all that energy after it was used. Edit: Oh, and while 1/2 of the Earth is receiving 400 GW/m^2, the other half is using that amount. Which would be the real limit. I don't think anybody would carry around a 10 GW iPhone 237+.
  - whatshisface 4y ago
    Why not have one square meter of radiators that emits gamma rays?
TheOtherHobbes 4y ago
Large parts of the Earth's surface are going to be generally uncomfortable within 10 years, never mind 200.
- formerkrogemp 4y ago
  Large parts of the Earth's surface are going to be generally uncomfortable now, never mind 10. Of course it'll be worse by then.
  - iso1631 4y ago
    Large parts of the Earth surface were generally uncomfortable in 1850, so that's not really a useful statement.
AtlasBarfed 4y ago
There's no way we achieve the higher powers of ten without a big infrastructure migration to space. Really that's the promise of those higher powers, you move from a terrestrial to a at least a solar civilization.

by lumost 4y ago

whatshisface 4y ago

That thermodynamic argument was the least convincing part. If you wanted to, you could beam your power plant's infrared radiation towards space, or put the plant itself in space and have it beam its waste heat away from the planet. The idea that heat dissipation is limited by the black body radiation of the Earth assumes that your house is part of the power plant's radiator, which itself implies that you will be living in a power plant's radiator. :-)

betwixthewires 4y ago
That's because you don't understand thermodynamics. You can't just put the power plant in space and keep the heat from generating the power away from the earth, because the heat gets created where the power is used to perform work. You have to avoid consuming any of that power on the earth entirely. And you can't just beam the waste heat from every process away from the surface of the earth, that violates the second law of thermodynamics. The heat exists because the energy performed work, you are keeping the energy organized by beaming it in any direction, so it is not waste heat, it is direct infrared from the energy you've produced. You can only do this by not actually using the energy for work. This makes the whole exercise of even producing the energy pointless. I think the biggest hole in the argument is the jump to 100% efficiency. we don't consume mor energy because we feel like it, we consume it because we need it, and a factor of 5 increase in efficiency would equate to a factor of 5 decrease in production of energy resources.
- whatshisface 4y ago
  >you are keeping the energy organized by beaming it in any direction I am afraid it is you who misunderstand thermodynamics, my friend. :-) Entropy is a matter of degree, and as long as the beam leaving the Earth is less ordered than the beam coming down, it can work. For example, imagine a hot nail on the moon suspended a few inches above a mirror. The heat will radiate into space and the moon won't get hotter.
  - betwixthewires 4y ago
    Yes, but that energy cannot be used for work on the moon...
    - taneq 4y ago
      Presumably the work is what heated the nail up in the first place…
      - betwixthewires 4y ago
        Yes, and if that work was done on the moon, the nail wouldn't be the only thing that was hot.
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- blueblimp 4y ago
  > And you can't just beam the waste heat from every process away from the surface of the earth, that violates the second law of thermodynamics. Surely this can't be right, because if it were, air conditioning (the normal everyday kind) would be impossible, right? What we're talking about here is loosely analogous to air conditioning the entire Earth (with the heat being sent to space rather than the outside air). Sounds like a hard engineering problem, but not impossible.
mbbutler 4y ago
But the energy transported to Earth from your space power plant still creates waste heat when it is used to do work (and also when it is transported to earth). You cannot beat the second law.
mgsouth 4y ago
Let us, per the article's title, do the math... * Total energy consumption = 10^26 watts (hope the caret comes through HN formatting) * Assume some magical generation and transport mechanisms which don't involve energy gradiants (avoiding pesky thermodynamic realities), and are 99.9% efficient. * Total waste energy is 10^23 watts. * Radiators are on Earth, and we dedicate 1/2 of the entire surface area (not just land) to radiators. Earth has about 5.1 x 10^8 km^2, so say 2.5 x 10^14 sq. meters. * Radiators for the waste heat would be dumping 10^23 W / 2.5 x 10^14 m^2 = 4 x 10^8 watts per square meter. That's 400 megawatts. Per square meter. * That's a black-body temperature of 9,165 K (the Sun's surface is 5,772 K). Peak wavelength is 316 nm. So half the Earth's surface is a glowing UV light pointed at the sky. I don't think we'd have to worry about the ozone layer disappearing. (A very bright, inefficient UV lamp--plenty of infrared, hard UV, and soft X-rays to go around!) * OK, so put the power plants in geostationary orbit. Say 1 million power stations, each with radiators 1 square kilometer. * 1e6 stations * 1e9 square meters = 1e15 sq meters. * So, that's only 1e8 watts/meter! Hmm. Still 6,480 K, but peak is blue-violet rather than UV. Still lots of UV and infrared, but it's space, who cares. Just don't cross the beams (ha ha, meaning no deep-space traffic). And mind the Moon! (Wouldn't want to give anbody on earth a reflected sunburn). * The radiation pressure from the waste engery for one power stations would be about 730 kN (160,000 pounds). Would need counter-balanced beams. * Geostationary orbit is about 26,000 miles. The surface area of a sphere that big is 2e16 square meters. So about 1/20th of the sky would be covered with powerplant radiators. And this is just for the hypothetical 0.1% waste energy. Multiply all of the above by 1,000 for the actual used energy. So you'd have half the Earth's surface as power receivers slurping up 400 gigawatts/square meter of X-rays and hard UV. Each power station would see a force of 739 mega-newtons; you'd have to have a counter-balancing beam pointing away from Earth. And then you'd need to radiate away all that energy after it was used. Edit: Oh, and while 1/2 of the Earth is receiving 400 GW/m^2, the other half is using that amount. Which would be the real limit. I don't think anybody would carry around a 10 GW iPhone 237+.
- whatshisface 4y ago
  Why not have one square meter of radiators that emits gamma rays?

TheOtherHobbes 4y ago

Large parts of the Earth's surface are going to be generally uncomfortable within 10 years, never mind 200.

formerkrogemp 4y ago
Large parts of the Earth's surface are going to be generally uncomfortable now, never mind 10. Of course it'll be worse by then.
- iso1631 4y ago
  Large parts of the Earth surface were generally uncomfortable in 1850, so that's not really a useful statement.

AtlasBarfed 4y ago

There's no way we achieve the higher powers of ten without a big infrastructure migration to space. Really that's the promise of those higher powers, you move from a terrestrial to a at least a solar civilization.