5 ms·

Plenty of water power.

yodon 5y ago
It takes a lot of tech to turn a River into a source of heat, and it takes still more tech to produce that tech that you need to pull it off. Water is an easy source of power for some things, but for most chemical processes what you need is heat (and most of the tech you're going to need to restart civilization is at some level going to be rooted in chemical processes)
- chmod775 5y ago
  > It takes a lot of tech to turn a River into a source of heat. No it doesn't. Turning motion into electricity is fairly easy, and turning electricity into heat is even more so. The biggest hurdle will be manufacturing quality mechanical parts, but you can do without quality in a pinch. Also producing heat is a matter of survival, not civilization. We can safely assume people will at least be able to make a fire.
  - yodon 5y ago
    You're thinking like a modern resident, not like someone living a decade after a global extinction event. Turning water into electricity requires significant infrastructure for making motors and generators and bearings and permanent magnets and transmission lines and the like (even if in principle the math/physics is easy)
    - chmod775 5y ago
      1. Bootstrap a smithy 2. Make incrementally better tools. You don't need to get to the level of medieval clockmakers, just as long as you're not hitting metal with a rock. 3. Make a draw plate. 4. Make lots and lots of copper wire. 5. Build a water wheel whichever way you want. 6. Attach bigger wheel (TM) and connect to smaller wheel (TM) with a rope drive. 7. Use copper wire to build a power generator attached to smaller wheel (TM). Unless humanity got completely wiped off the planet with no artifacts left behind, most of the above should not be necessary though.
      - yodon 5y ago
        It's all well and good to be optimistic, I'm a MacGyver too, but when society only gets one roll of the dice to restart after a mass extinction event I don't think it's advisable to discount the difficulties and challenges society will face trying to restart, with access to accessible energy sources being a major component of those challenges.
      - bilbo0s 5y ago
        Maybe my brain's groggy, but how are we achieving self-excitation in this scenario? (I'm assuming there's no magnet in your setup as it's not explicitly called out.)
        chmod775 5y ago
        No. Of course you need a magnet if you don't want to build a more complicated self-excitation design (building that would be quite the feat given the circumstances) or want to use a smaller dynamo to bootstrap an electromagnetic dynamo or even alternator. But it's better to start with a magnet and stick to easy-to-debug stuff that can be eyeballed start to finish.
      - vkou 5y ago
        > 1. Bootstrap a smithy I would recommend learning about what is involved in this step, before moving on to step 2. https://acoup.blog/2020/09/18/collections-iron-how-did-they-make-it-part-i-mining/ https://acoup.blog/2020/09/18/collections-iron-how-did-they-... This process is incredibly difficult, made moreso by the lack of easily accessible surface ore/coal. Also, keep in mind that when agricultural productivity is in the pits (Due to a lack of tooling, chemical feedstock, massive infrasturcture projects), and when you don't have the ability to make synthetic clothing (Which leads you to working with natural fibers, which is an incredibly labour-intensive process[1]), you aren't going to have the spare calories, or the hours in your day to 'just bootstrap a smithy'. [1] https://acoup.blog/2021/03/05/collections-clothing-how-did-they-make-it-part-i-high-fiber/ https://acoup.blog/2021/03/05/collections-clothing-how-did-t...
      - roca 5y ago
        Where do you get the copper ore in this scenario? Existing natural easy-to-access ores have been mined out already. Would it be possible to mine the detritus of our civilization to get these ores?
- FooBarBizBazz 5y ago
  You can turn work into heat with friction or turbulence. You don't need electrical thingamajigs. But even "small" amounts of heat involve huge amounts of energy. If I haven't just made a mistake, it takes 40 MJ to raise a bathtub full of water from room temperature to bathwater temperature. Better to use trees and wood for heat: The original solar power system.
  - FooBarBizBazz 5y ago
    Redoing the math, I get more like 20 MJ to heat a bathtub. For comparison, supposedly Teslas ship with 80 kWh = 288 MJ batteries. So you can take 14.6 baths with the energy in that battery. That's more than I'd expected.

It takes a lot of tech to turn a River into a source of heat, and it takes still more tech to produce that tech that you need to pull it off. Water is an easy source of power for some things, but for most chemical processes what you need is heat (and most of the tech you're going to need to restart civilization is at some level going to be rooted in chemical processes)

chmod775 5y ago
> It takes a lot of tech to turn a River into a source of heat. No it doesn't. Turning motion into electricity is fairly easy, and turning electricity into heat is even more so. The biggest hurdle will be manufacturing quality mechanical parts, but you can do without quality in a pinch. Also producing heat is a matter of survival, not civilization. We can safely assume people will at least be able to make a fire.
- yodon 5y ago
  You're thinking like a modern resident, not like someone living a decade after a global extinction event. Turning water into electricity requires significant infrastructure for making motors and generators and bearings and permanent magnets and transmission lines and the like (even if in principle the math/physics is easy)
  - chmod775 5y ago
    1. Bootstrap a smithy 2. Make incrementally better tools. You don't need to get to the level of medieval clockmakers, just as long as you're not hitting metal with a rock. 3. Make a draw plate. 4. Make lots and lots of copper wire. 5. Build a water wheel whichever way you want. 6. Attach bigger wheel (TM) and connect to smaller wheel (TM) with a rope drive. 7. Use copper wire to build a power generator attached to smaller wheel (TM). Unless humanity got completely wiped off the planet with no artifacts left behind, most of the above should not be necessary though.
    - yodon 5y ago
      It's all well and good to be optimistic, I'm a MacGyver too, but when society only gets one roll of the dice to restart after a mass extinction event I don't think it's advisable to discount the difficulties and challenges society will face trying to restart, with access to accessible energy sources being a major component of those challenges.
    - bilbo0s 5y ago
      Maybe my brain's groggy, but how are we achieving self-excitation in this scenario? (I'm assuming there's no magnet in your setup as it's not explicitly called out.)
      - chmod775 5y ago
        No. Of course you need a magnet if you don't want to build a more complicated self-excitation design (building that would be quite the feat given the circumstances) or want to use a smaller dynamo to bootstrap an electromagnetic dynamo or even alternator. But it's better to start with a magnet and stick to easy-to-debug stuff that can be eyeballed start to finish.
    - vkou 5y ago
      > 1. Bootstrap a smithy I would recommend learning about what is involved in this step, before moving on to step 2. https://acoup.blog/2020/09/18/collections-iron-how-did-they-make-it-part-i-mining/ https://acoup.blog/2020/09/18/collections-iron-how-did-they-... This process is incredibly difficult, made moreso by the lack of easily accessible surface ore/coal. Also, keep in mind that when agricultural productivity is in the pits (Due to a lack of tooling, chemical feedstock, massive infrasturcture projects), and when you don't have the ability to make synthetic clothing (Which leads you to working with natural fibers, which is an incredibly labour-intensive process[1]), you aren't going to have the spare calories, or the hours in your day to 'just bootstrap a smithy'. [1] https://acoup.blog/2021/03/05/collections-clothing-how-did-they-make-it-part-i-high-fiber/ https://acoup.blog/2021/03/05/collections-clothing-how-did-t...
    - roca 5y ago
      Where do you get the copper ore in this scenario? Existing natural easy-to-access ores have been mined out already. Would it be possible to mine the detritus of our civilization to get these ores?
FooBarBizBazz 5y ago
You can turn work into heat with friction or turbulence. You don't need electrical thingamajigs. But even "small" amounts of heat involve huge amounts of energy. If I haven't just made a mistake, it takes 40 MJ to raise a bathtub full of water from room temperature to bathwater temperature. Better to use trees and wood for heat: The original solar power system.
- FooBarBizBazz 5y ago
  Redoing the math, I get more like 20 MJ to heat a bathtub. For comparison, supposedly Teslas ship with 80 kWh = 288 MJ batteries. So you can take 14.6 baths with the energy in that battery. That's more than I'd expected.