5 ms·

what about a gravity battery? and it can serve as a space catapult sometimes too

rusk 10y ago
You mean like this? https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
- jessaustin 10y ago
  It's not obvious how a "space catapult" could be built from that...
  - rusk 10y ago
    LOL I'm not sure it's obvious how a space-catapult could be built at all .. I'm pretty sure some Darwin nominee would have tried it by now if so /s Come to think of it - the "obvious" flaw to this whole scheme is the need to store enough energy gravitationally and then release it such that it projects something beyond earth's gravitational pull. Strikes me as a non-trivial engineering problem ...
    - Filligree 10y ago
      It's nontrivial, but eventually doable. We'll get there if we want to. No, the bigger problem is the atmosphere. It'll have to go.
    - jlebrech 10y ago
      no need for Darwin nominees, only send equipment via mass drivers.
- marcosdumay 10y ago
  Probably this: https://en.wikipedia.org/wiki/Space_fountain https://en.wikipedia.org/wiki/Space_fountain
  - rusk 10y ago
    That is very cool, thanks. I don't think it could be used for energy storage though. Its major disadvantages come about from the fact that it is an extremely-high-energy active structure. It requires constant power input to make up energy losses and remain erect.
    - marcosdumay 10y ago
      Wikipedia used to have a much more elaborated explanation on them. A superconductive structure with evacuated rails wouldn't need energy to stay in place (always in theory - one would certainly need something active). An electromagnetic one will use a lot of power, but still much less than the amount stored. Sill, it's not something simple that one could deploy today.
adrianN 10y ago
Also known as pumped hydro?
- jlebrech 10y ago
  or a vacuum u-bend. and the weight is pulleyed up slowly and dropped when it reaches the right altitude and when it has thrown it's payload it's attached to another set of pulleys on the other side and reset.
- jlebrech 10y ago
  i reinvented the space fountain, so ignore that.
beat 10y ago
There are a variety of gravity-driven storage solutions out there. Heavy railcars on steep slopes has gotten some HN attention before. The real point is, there are numerous ways to solve the storage problem, some of which are geologically specific (allowing for some reduced cost due to local landscape features).
- woodandsteel 10y ago
  My understanding is that electric power is very efficient at moving heavy rail cars up a mountain, so surprisingly little power gets stored.
  - beat 10y ago
    What you mean is that little power gets lost, not little power gets stored. The goal is to reduce thermal losses. Beyond that, it's just a matter of throwing mass at the problem. These aren't ordinary rail cars. They're designed to be generators, so they optimize for efficiency. Adding mass increases storage, but we don't want to waste more energy than necessary in the storage process.
    - woodandsteel 10y ago
      Yes, you are right that I should have said little power gets lost. I thought about it some more, and I think the underlying problem is that even these very heavy rail cars don't have nearly enough mass. Compare them with the literally millions of tons of water in an even moderate-sized reservoir.
      - beat 10y ago
        Water is 1000kg/m^3. Cast iron is 7300kg/m^3, so there's a substantial density difference. More important, though, is geography. A place with long, steep, relatively straight slopes isn't necessarily a good place to build a reservoir.
        10y ago

rusk 10y ago

You mean like this? https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...

jessaustin 10y ago
It's not obvious how a "space catapult" could be built from that...
- rusk 10y ago
  LOL I'm not sure it's obvious how a space-catapult could be built at all .. I'm pretty sure some Darwin nominee would have tried it by now if so /s Come to think of it - the "obvious" flaw to this whole scheme is the need to store enough energy gravitationally and then release it such that it projects something beyond earth's gravitational pull. Strikes me as a non-trivial engineering problem ...
  - Filligree 10y ago
    It's nontrivial, but eventually doable. We'll get there if we want to. No, the bigger problem is the atmosphere. It'll have to go.
  - jlebrech 10y ago
    no need for Darwin nominees, only send equipment via mass drivers.
marcosdumay 10y ago
Probably this: https://en.wikipedia.org/wiki/Space_fountain https://en.wikipedia.org/wiki/Space_fountain
- rusk 10y ago
  That is very cool, thanks. I don't think it could be used for energy storage though. Its major disadvantages come about from the fact that it is an extremely-high-energy active structure. It requires constant power input to make up energy losses and remain erect.
  - marcosdumay 10y ago
    Wikipedia used to have a much more elaborated explanation on them. A superconductive structure with evacuated rails wouldn't need energy to stay in place (always in theory - one would certainly need something active). An electromagnetic one will use a lot of power, but still much less than the amount stored. Sill, it's not something simple that one could deploy today.

adrianN 10y ago

Also known as pumped hydro?

jlebrech 10y ago
or a vacuum u-bend. and the weight is pulleyed up slowly and dropped when it reaches the right altitude and when it has thrown it's payload it's attached to another set of pulleys on the other side and reset.
jlebrech 10y ago
i reinvented the space fountain, so ignore that.

beat 10y ago

There are a variety of gravity-driven storage solutions out there. Heavy railcars on steep slopes has gotten some HN attention before. The real point is, there are numerous ways to solve the storage problem, some of which are geologically specific (allowing for some reduced cost due to local landscape features).

woodandsteel 10y ago
My understanding is that electric power is very efficient at moving heavy rail cars up a mountain, so surprisingly little power gets stored.
- beat 10y ago
  What you mean is that little power gets lost, not little power gets stored. The goal is to reduce thermal losses. Beyond that, it's just a matter of throwing mass at the problem. These aren't ordinary rail cars. They're designed to be generators, so they optimize for efficiency. Adding mass increases storage, but we don't want to waste more energy than necessary in the storage process.
  - woodandsteel 10y ago
    Yes, you are right that I should have said little power gets lost. I thought about it some more, and I think the underlying problem is that even these very heavy rail cars don't have nearly enough mass. Compare them with the literally millions of tons of water in an even moderate-sized reservoir.
    - beat 10y ago
      Water is 1000kg/m^3. Cast iron is 7300kg/m^3, so there's a substantial density difference. More important, though, is geography. A place with long, steep, relatively straight slopes isn't necessarily a good place to build a reservoir.
      - 10y ago