[HN Gopher] Galactic-Scale Energy - Do the Math (2011) ___________________________________________________________________ Galactic-Scale Energy - Do the Math (2011) Author : grey_earthling Score : 26 points Date : 2022-07-23 08:46 UTC (14 hours ago) (HTM) web link (dothemath.ucsd.edu) (TXT) w3m dump (dothemath.ucsd.edu) | pdonis wrote: | The article leaves out a crucial point: the main driver of growth | in energy usage is growth in human population. The human | population of Earth is expected to level off this century. So any | projection beyond that that assumes continued energy growth at | the same rate is not realistic. | zamalek wrote: | The article does mention this: | | > Chiefly, continued energy growth will likely be unnecessary | if the human population stabilizes. | aaaaaaaaaaab wrote: | In other words: the exponential function grows very fast. | NickM wrote: | I don't think most people advocate for indefinite growth of | energy usage; when people talk about sustainability of growth | they are typically referring to economic growth. This has often | been correlated with energy usage in the past but there's nothing | that says it has to be that way, and indeed there are a number of | countries that have shown that decoupling the two is possible: | https://ourworldindata.org/energy-gdp-decoupling | api wrote: | It tends to be tightly correlated to energy use up to a certain | material standard of living. At that point they start to | decouple. | mbbutler wrote: | They don't even decouple at high material standards of | living. Recent increases to GDP produced emissions too but | those new emissions were offset by reductions in emissions of | existing industries. | | This "decoupling" gets us basically nothing because it's not | like we can just stop emissions tomorrow since GDP and | emissions are "decoupled". | epicureanideal wrote: | Counter example: if we can make computation 1000x more | efficient per teraflop, we could use computers to trivially | design drugs to cure cancer etc (just a random example) and | yet our energy consumption would not change. GDP may be the | wrong measure, but there would be economic growth or | standard of living growth for no change in energy | consumption. | mathgeek wrote: | > if we can make computation 1000x more efficient per | teraflop, we could use computers yo trivially design new | drugs to cure cancer etc | | You're assuming two things: that cancer and disease can | be cured by any feasible increase in computing power (not | that outrageous an assumption), and that the energy | savings won't be offset by keeping an even older | population of disease survivors comfortable and alive. | Reality is not as simple as "cure all our ailments and | we're good to go". | TheOtherHobbes wrote: | This has already happened at a higher multiplier. | | An Apple Watch has more processing power than a Cray 2, | but it uses a rechargeable battery instead of a 150kW | power supply. | | The problem is that cycles expand to fill the space | available, so another 1000X drop in efficiency would mean | new kinds of applications rather than being limited to | affordable super computing. | | While individual computers are far more powerful and use | far less energy, the power consumed by computing on Earth | as a whole is far higher than it was. (Not even counting | energy vampires like crypto.) | | There's no reason to assume that trend would stop. | Displays could easily have much higher resolutions | (possibly holographic), IOT could be truly ubiquitous, AI | could be in everything, entertainment could be social, | interactive, and immersive, and so on. | Jweb_Guru wrote: | This article (and site) are pretty great, and helped shape a lot | of my worldview. It tends to throw a bucket of cold water on a | lot of the arguments regularly made on this website, though, so | I'm surprised to see it here. | epistasis wrote: | What sort of arguments do you see made on this website that | this would refute? | carapace wrote: | See also: "Exponential Economist Meets Finite Physicist" which | covers the same material in the context of economic growth. | | > Some while back, I found myself sitting next to an accomplished | economics professor at a dinner event. Shortly after | pleasantries, I said to him, "economic growth cannot continue | indefinitely," just to see where things would go. It was a lively | and informative conversation. | | https://dothemath.ucsd.edu/2012/04/economist-meets-physicist... | yrgulation wrote: | > I have always been impressed by the fact that as much solar | energy reaches Earth in one hour as we consume in a year. What | hope such a statement brings! But let's not get carried away-- | yet. | | > The abundance of deuterium in ordinary water would allow us to | have a seemingly | | I mean isn't it obvious that we are missing opportunities here? | Are we really that complacent that we can't achieve anything on a | grand scale anymore? Plant solar panels everywhere that there is | not agricultural land and meets the criteria for energy | efficiency. Fill in the all the roofs. It's vacant space. Spend | billions more on fusion research. | | > The merciless growth illustrated above means that in 1400 years | from now, any source of energy we harness would have to outshine | the sun. | | Hopefully by that time we'd be an interplanetary species. Unless | we imagine we can keep digging all the way to the core to extract | resources down here. When all the good stuff is literally sitting | out there waiting for us to plunder. | | > Chiefly, continued energy growth will likely be unnecessary if | the human population stabilizes. | | I doubt our insatiable hunger for more, more, and more will stop | anytime soon - even if the numbers stagnate, our egos will grow | bigger and bigger and we'll want more and more. It's in our | nature. So why not go beyond our planet for that never-ending | "want"? Consumer everything that's out there and turn into shiny | new crap for down here. Once we are done, eject it into the sun | and keep the earth tidy. | tener wrote: | Feels like a similar methodology here https://xkcd.com/605/ | [deleted] | akira2501 wrote: | Thankfully, the planet contains abundant stores of Uranium.. and | we are nowhere near peak efficiency in commercial and industrial | processes. These one dimensional analysis of the problem are | particularly useless, especially when their only conclusion is | "we must stop growth." | | The average power usage may well be 2000W, but how many average | consumers are there? If we're facing a multi-mode distribution of | those users, then this "stop growth" strategy instantly creates | new "castes" from this distribution. As a long term strategy, it | seems doomed in one way or another. | api wrote: | These analyses have been predicting doom for decades. They just | keep moving the goal post. | Arthur8 wrote: | Huh, I had to re-read the article _. | | "But let's not overlook the key point: continued growth in | energy use becomes physically impossible within conceivable | timeframes." (conceivable timeframes ~ few 100 years) | | As far as I understood, the argument is not "we are doomed" | but that there is a natural limit to the growth of energy | consumption in the not too distant future using some naive | assumptions. In any case, it is implying that 2.9% growth per | year is a lot! if it is extrapolated by just a few 100 years. | Do I misunderstand something? Why is this controversial? | | _But I did not yet read all the linked later posts. | Jweb_Guru wrote: | You are correct. | lumost wrote: | 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 wrote: | 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. :-) | mbbutler wrote: | 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. | betwixthewires wrote: | 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 wrote: | > _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. | TheOtherHobbes wrote: | Large parts of the Earth's surface are going to be generally | uncomfortable within 10 years, never mind 200. ___________________________________________________________________ (page generated 2022-07-23 23:00 UTC)